Check out our New Publishers' Select for Free Articles

Applied Catalysis A, General (v.417-418, #)

Editorial Board (pp. co2).

Contents (pp. iii-xii).

Evaluation of catalytic activity in ethylene polymerization and ethylene/10-undecen-1-ol copolymerization of new orthopalladated complexes derived from tridentade ligands [C,N,S] by Fernando Ortega-Jiménez; José G. López-Cortés; M. Carmen Ortega-Alfaro; J. Guillermo Penieres-Carrillo; Raúl Quijada; Cecilio Alvarez-Toledano (pp. 1-5).

Display Omitted► Orthopalladated complex/MAO systems have high activity in ethylene polymerization. ► Polyethylene obtained is linear with narrow molecular weight distributions. ► Orthopalladated complex/MAO systems produce ethylene/10-undecen-1-ol copolymer with high activities. ► Pd/Al systems behave as single site catalysts in both cases.This paper describes catalytic applications of new orthopalladated complex/MAO systems in polymerization of ethylene and copolymerization of ethylene/10-undecen-1-ol. Orthopalladated complexes1–5 were synthesized from tridentate ligands [C, N, S], with a general formula of PdLX, where L=[Ph₂NNC(CH₃)CSRSR] and R=CH₃,CH₂CH₂ and X=Cl,CCPh,CCSi(CH₃)₃. These catalytic systems show high catalytic activity in ethylene polymerization, especially when the reactions were carried out at a temperature of 80°C. The polyethylene obtained is linear with narrow molecular weight distributions, indicating that Pd/Al systems behave as single site catalysts. The results obtained in copolymerization of ethylene/10-undecen-1-ol indicate that orthopalladated complex/MAO system produces copolymers with molecular weight distributions unimodal and close to 2, indicating that the Pd/Al systems also act as single site catalysts.

Keywords: Orthopalladated complexes; Ethylene polymerization; Copolymerization

CeO₂-catalyzed one-pot selective synthesis of N-alkyl amides from nitriles, amines and water by Masazumi Tamura; Takuya Tonomura; Ken-ichi Shimizu; Atsushi Satsuma (pp. 6-12).

Display Omitted► First example for one-pot N-alkyl amides synthesis from heteroaromatic nitriles and amines under neutral conditions. ► Commercial CeO₂ as the most active catalyst among various metal oxides. ► Effective synthetic method of pharmaceutically important heteroaromatic amides.Among 13 kinds of metal oxides, ceria (CeO₂) shows the highest catalytic activity for one-pot selective synthesis of the secondary amide from 2-cyanopyridine and n-octylamine as a test reaction. CeO₂ acts as a reusable heterogeneous catalyst, and it is effective for the secondary amide formation from various nitriles and amines in high yields (73% to >99%). Pharmacologically important products such as heteroaromatic N-alky amides and morpholine amide are effectively synthesized, indicating that CeO₂ can be a practically useful catalyst. A proposed mechanism includes (1) hydration of nitrile to the primary amide and (2) transamidation of the primary amide with amine as the rate-limiting step. This reaction mechanism provides a reason why the present catalytic system gives high selectivity.

Keywords: Cerium oxide; Amides; One-pot synthesis

A novel nanoengineered VO_x catalyst supported on highly ordered TiO₂ nanotube arrays for partial oxidation reactions by Jose E. Herrera; Tayirjan T. Isimjan; Inusa Abdullahi; Ajay Ray; Sohrab Rohani (pp. 13-18).

Display Omitted► Nanoengineered VO_x on a highly ordered TiO₂ nanotube prepared through CVD. ► Highly dispersed vanadia phase present on the surface of the TiO₂ nanotube array. ► Ethanol partial oxidation used to evaluate the catalytic activity of this material.A new class of nanoengineered partial oxidation catalyst has been prepared through the use of chemical vapor deposition of a vanadium oxide precursor over a highly ordered TiO₂ nanotube array. A battery of characterization techniques including X-ray diffraction (XRD) together with scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS), Raman, and DRS-UV/vis indicate that the vanadia species are extremely well dispersed onto the surface of the nanotube array. Studies of the catalytic activity of this material were performed using the partial oxidation of ethanol as a probe reaction and compared with those obtained using typical P-25 TiO₂ powdered support. Results showed that the nanoengineered approach to catalyst fabrication leads to a highly active catalytic material where most of the vanadium oxide phase is located on the surface and accessible for catalysis.

Keywords: Vanadium oxide; Partial oxidation; Ethanol; TiO; ₂; nanotubes; UV–vis; XRD; XPS; Raman; SEM

Effect of TiO₂ on the hydrodesulfurization performance of bulk Ni₂P by Xiang Li; Zhichao Sun; Anjie Wang; Xiuna Yang; Yao Wang (pp. 19-25).

.Display Omitted► Preparation of TiO₂-doped bulk Ni₂P hydrodesulfurization catalysts. ► The catalytic activity of Ni₂P was substantially improved by the addition of TiO₂. ► The oxidability of Ni₂P was affected by TiO₂. ► Ni was formed in the presence of TiO₂.The bulk Ni₂P and TiO₂-doped bulk Ni₂P (Ti–Ni₂P( x), x represents the Ti/Ni atomic ratio) were prepared by a co-precipitation method followed by an in-situ H₂ temperature-programmed reduction procedure. The passivated catalysts were characterized by N₂ adsorption–desorption method and X-ray absorption spectroscopy (XAS). Their hydrodesulfurization (HDS) performances were studied using dibenzothiophene (DBT) as the model molecule. The XAS results indicated that Ti–Ni₂P(0.01) and Ti–Ni₂P(0.03) were more oxidized than the other samples during passivation. The EXAFS analysis showed that Ni was formed in the presence of TiO₂. The coordination number of NiNi shell of Ni in Ti–Ni₂P( x) reached its maximum at a Ti/Ni atomic ratio=0.05. The HDS activity of Ni₂P was substantially improved by the introduction of TiO₂. TiO₂ had different promoting effects on the direct desulfurization pathway and the hydrogenation pathway activities of Ni₂P. The promoting effect of TiO₂ is discussed by considering the electronic interactions between surface TiO₂ and Ni₂P species and the variations in the active site distributions.

Keywords: Nickel phosphide; TiO; ₂; Hydrodesulfurization; Dibenzothiophene; Promoting

Comparative study on UV and visible light sensitive bare and doped titanium dioxide photocatalysts for the decomposition of environmental pollutants in water by G. Veréb; Z. Ambrus; Zs. Pap; Á. Kmetykó; A. Dombi; V. Danciu; A. Cheesman; K. Mogyorósi (pp. 26-36).

Display Omitted► I, N, Fe doped and Ag, Au deposited TiO₂ were compared with reference titanias. ► Non-doped flame made titanias showed the best activity for UV/phenol decomposition. ► Ag, Au deposition enhanced significantly the oxalic acid degradation in UV light. ► Nitrogen doped titania owns the highest efficiency for phenol under visible light. ► The activity order for oxalic acid under VIS irradiation is TiO₂-Fe≫TiO₂-N≈P25.In this study the efficiency of different bare, doped and composite photocatalysts were compared, under UV and visible light irradiation in order to show a detailed picture of the relative performance of the best photocatalysts developed in our laboratories and the mostly investigated reference titanias. The syntheses of our photocatalysts were optimized in order to achieve maximum photocatalytic activity under UV and visible light irradiation. Non doped commercial (Aeroxide P25, Aldrich anatase) and synthesized titanias (produced by sol–gel and flame hydrolysis techniques) and nitrogen, iron, iodine doped and silver or gold deposited titanium dioxides were investigated with two model pollutants (phenol and oxalic acid) under identical experimental conditions. The material properties of these selected photocatalysts were thoroughly characterized by X-ray diffraction, diffuse reflectance spectroscopy, transmission electron microscopy, X-ray photoelectron spectroscopy, X-ray fluorescence spectroscopy and BET methods. The highest degradation rate of phenol was determined for the flame made titania sample with relatively low specific surface area (20m²/g) when UV irradiation was applied. In contrast with that, our nitrogen doped photocatalyst with high specific surface area (139m²/g) was the best for phenol degradation under visible light irradiation. Although the most efficient oxalic acid mineralization occurred with noble metal photodeposited samples under UV irradiation, this type of modification was detrimental when VIS irradiation is applied. The decomposition rate of oxalic acid was high under VIS irradiation using the iron and nitrogen doped photocatalysts. For both substrates and irradiation conditions our best photocatalysts were found to be significantly more active than Aeroxide P25 TiO₂. Intermediate studies revealed that phenol degradation resulted in dihydroxy benzene intermediates, such as pyrocatechol and hydroquinone both under UV and visible light irradiation with our TiO₂-N photocatalyst. The results of this comparative study could promote the determination of the optimal synthesis conditions of titanium dioxide based photocatalysts for a given organic pollutant in water.

Keywords: Flame hydrolysis; Doped titania; Noble metal deposition; Photocatalysis; Visible light

Sulfur promoted Pt/SiO₂ catalyzed cross-coupling of anilines and amines by Ken-ichi Shimizu; Katsuya Shimura; Naoko Tamagawa; Masazumi Tamura; Atsushi Satsuma (pp. 37-42).

Display Omitted► S-loading enhances the TOF of Pt/SiO₂ by a factor of more than 5. ► Effective for cross-coupling reactions of various anilines and amines. ► Higher TOF than previous heterogeneous and homogeneous catalysts in the literature.Pt/SiO₂ (Pt=5wt%) catalysts with average Pt particle size of 3.3 and 6.8nm and sulfur-loaded Pt/SiO₂ (S/Pt ratio=0.1 and 0.13; Pt size=5.2 and 5.5nm), prepared by adding ammonium sulfate on Pt/SiO₂ followed by H₂-reduction at 500°C, are tested for mono- N-alkylation of aniline with di- iso-propylamine. The turnover frequency (TOF), defined as the reaction rate per number of surface Pt species, increases with sulfur loading. The catalyst with S/Pt ratio of 0.13 shows more than 5 times higher TOF than unmodified catalysts, and it acts as effective and recyclable catalyst for cross-coupling of various anilines and amines. Combined with kinetic results and characterizations, XAFS (X-ray absorption fine structure), TEM, and CO adsorption IR, a possible reason for the promotion effect of sulfur species (probably sulfidic species) is discussed.

Keywords: Amines; Cross-coupling; Platinum; Sulfur

Application of ETS-10 microporous titanosilicate as support of Ru nanoparticles for hydrogen production by B.M. Faroldi; E.A. Lombardo; L.M. Cornaglia; S. Irusta (pp. 43-52).

Display Omitted► Microporous titanosilicates were synthesized to be applied as supports for Ru catalysts. ► In the case of the solid exchanged with dilute solution Ru is at exchange positions. ► For the impregnated catalyst, the Ru nano-particles were better dispersed. ► These catalysts were active and stable for the dry reforming of methane. ► Forward CH₄ turnover frequencies increase with the increase in Ru dispersion.Supported ruthenium catalysts have been shown to be effective for the dry reforming of methane. Besides, ETS-10 titanosilicate has properties able to disperse Ru species. In this work, microporous ETS-10 titanosilicate was synthesized by hydrothermal synthesis employing anatase as Ti source. Ru was incorporated using three different methods: by incipient wetness impregnation (RuH), by ion exchange (RuI) and by adding Ru to the gel synthesis (RuG). The species present in the solids were characterized by XRD, N₂ adsorption, ICP, SEM, TEM, EDX, TGA, TPR, UV–vis and XPS.RuH and RuI catalysts were found to be active and stable for the dry reforming of methane. These results show the potential application of ETS-10 as support of Ru catalysts for the production of hydrogen.

Keywords: Ruthenium; ETS-10; Dry reforming; Hydrogen production

A novel CeO₂ supported on carbon nanotubes coated with SiO₂ catalyst for catalytic cracking of naphtha by Kamyar Keyvanloo; Ali Mohamadalizadeh; Jafar Towfighi (pp. 53-58).

.Display Omitted► Cerium oxide on carbon nanotube coated with silicon dioxide as catalyst. ► Catalysts for steam catalytic cracking of hydrocarbons. ► SiO₂-coated CNT has oxidization temperature about 80°C higher than that of uncoated one. ► SiO₂-coated CNT generates new acidic sites and improves redox property. ► Si–Ce/CNT has highest total acid sites and yield of light olefins.Carbon nanotubes (CNTs) supported ceria catalysts coated with silica were used in catalytic cracking of naphtha to increase the yield of ethylene and propylene. Coating of CNTs was carried out with a pH control chemical deposition method using Si precursor. TGA results on coated CNTs showed 80°C improvement in the thermal stability compared to uncoated CNT. XRD, SEM, and TEM analysis indicated that the structure of the CNT remained intact after modification. The silicon partly coated the CNT walls and the CeO₂ entered the CNT channel or was deposited on the wall. Measurement of the total acidity and number of Brønsted acid sites with NH₃-TPD and FTIR measurements exhibited that the total acid concentration and Brønsted acid sites of modified CNTs increased. TPR results showed that the presence of Si species slightly improved the reduction of CeO₂. As a result, catalyst Si–Ce/CNT showed a better catalytic cracking performance than catalysts Ce/CNT, Si/CNT or CNT.

Keywords: Carbon nanotubes; Silica coating; CeO; ₂; Light olefins; Catalytic cracking

Gas phase hydrogenation of maleic anhydride at low pressure over silica-supported cobalt and nickel catalysts by Camilo I. Meyer; Silvina A. Regenhardt; Alberto J. Marchi; Teresita F. Garetto (pp. 59-65).

Display Omitted► Ni/SiO₂ and Co/SiO₂ showed hydrogenolytic activity in maleic anhydride hydrogenation. ► Succinic anhydride was converted into γ-butyrolactone and propionic acid at 1bar. ► Hydrogenolytic metal sites were selectively deactivated by carbonaceous compounds.The gas-phase hydrogenation of maleic anhydride over Ni/SiO₂ and Co/SiO₂ catalysts, prepared by the incipient wetness impregnation method, was studied. The catalytic tests were carried out at 1bar pressure, between 170 and 220°C andW/FMA0 in the range 5–25ghmol⁻¹. In this work, the product distribution was different to those obtained at high pressures, previously reported in the open literature. Both Ni/SiO₂ and Co/SiO₂ catalysts were active for the selective hydrogenation of maleic anhydride (MA) into succinic anhydride (SA). Subsequently, SA was converted to γ-butyrolactone (GBL) and propionic acid (PA). Neither tetrahydrofurane nor butanediol were detected at the reactor outlet. GBL/PA ratio was strongly depending on the metallic catalyst and temperature. At 170°C, Ni/SiO₂ was more selective to GBL than Co/SiO₂. Besides, with Ni/SiO₂, GBL formation rate diminished during the experiment while PA production showed a small increase. Instead, over Co/SiO₂, both the PA and GBL formation rate decayed with time on stream. At 220°C, Co/SiO₂ showed a higher initial selectivity to GBL than Ni/SiO₂. However, the GBL formation rate diminished more rapidly with Co/SiO₂ than with Ni/SiO₂. Thus, both catalysts gave similar selectivity to GBL after 3h reaction at 220°C. The observed catalyst deactivation was attributed to carbonaceous species of different nature deposited on the metallic phase during reaction. The amount and type of these species depends on both metal catalysts and reaction conditions. Selectivity and stability of Ni/SiO₂ and Co/SiO₂ catalysts is explained on the basis of their hydrogenolytic activity.

Keywords: Selective hydrogenation; Maleic anhydride; γ-Butyrolactone; Metal-based catalysts

Selective oxidation of CO in H₂-rich stream over Au/CeO₂ and Cu/CeO₂ catalysts: An insight on the effect of preparation method and catalyst pretreatment by Salvatore Scirè; Carmelo Crisafulli; Paolo Maria Riccobene; Giacomo Patanè; Alessandro Pistone (pp. 66-75).

Display Omitted► The PROX activity is influenced by preparation method and catalysts pretreatment. ► Au nanoparticle size strongly affects the PROX reaction on Au/CeO₂. ► Ceria morphology has a key role in determining the performance of Cu/CeO₂. ► Au/CeO₂ and Cu/CeO₂ catalysts are good catalysts for the PROX reaction.Selective oxidation of CO in H₂-rich stream was studied on Au/CeO₂ and Cu/CeO₂ catalysts, investigating the effect of both the preparation technique and the catalyst pretreatment towards the catalytic performance. It was found that in the case of Au catalysts the sample prepared by deposition–precipitation was more active than that prepared by co-precipitation. The opposite trend was instead observed on Cu samples. On all tested catalysts a higher pre-calcination temperature of catalysts resulted in a lower CO conversion. The extent of this effect was strong on Au samples and less evident on Cu ones. On both Au and Cu samples selectivity towards CO oxidation decreased on increasing reaction temperature, being almost independent from preparation and pretreatment. On the basis of characterisation data (H₂-TPR, XRD, XPS, and BET surface area) the effect of preparation method and catalyst pretreatment was accounted for both the different particle size and surface amount of active species (Au or CuO_x). According to a Mars-van Krevelen mechanism, implying lattice oxygens of the cerium oxide and CO (and H₂) adsorbed on the active species, it was suggested that on Au/CeO₂ the PROX reaction is strongly affected by the status of gold, which has a key role in the CO activation step, whereas on Cu/CeO₂ the performance are significantly influenced by the ceria morphology/reactivity.

Keywords: Gold; Copper; Cerium oxide; Preferential oxidation; PROX; Deposition; Co-precipitation

Effect of extra-framework Al formed by successive steaming and acid leaching of zeolite MCM-22 on its structure and catalytic performance by R.M. Mihályi; M. Kollár; P. Király; Z. Karoly; V. Mavrodinova (pp. 76-86).

Display Omitted► Extra-framework Al (EFAl) species remain captured in steam-acid dealuminated MCM-22. ► EFAl blocks the micropores and makes the acid sites isolated and inefficient. ► Reduced adsorption capacity and catalytic activity in m-xylene conversion. ► Enhanced p-xylene selectivity and change in coke composition.Dealuminated MCM-22 samples have been prepared by a two-step dealumination procedure. Detailed assessment of the properties of the materials obtained at each one of the successive stages, i.e. steaming (at 500°C, 700°C and 800°C) and acid reflux (HCl and oxalic), has been made by XRD, N₂ adsorption–desorption, m-xylene adsorption,²⁷Al MAS NMR and FT-IR of pyridine adsorption. It was found that steaming generates extra-framework aluminum (EFAl) species and the majority of them cannot be extracted by the consecutive acid leaching. These extra-lattice entities block the zeolite micropores which makes the remaining Broensted acid sites isolated and inefficient. It is shown that the presence of such species vastly affects the catalytic performance of zeolite MCM-22 in the reaction of m-xylene conversion. The consequences are reduced adsorption capacity and catalytic activity, modified reaction products distribution, enhanced p-xylene selectivity, as well as altered mode of coke formation and composition of the coke precursors.

Keywords: MCM-22 zeolite; Steam-acid dealumination; Extra-framework Al; m; -Xylene conversion; Coke formation

Performance of vanadium based catalyst in a membrane contactor for the benzene hydroxylation to phenol by Raffaele Molinari; Cristina Lavorato; Teresa Poerio (pp. 87-92).

Display Omitted► The membrane reactor (MR) gave 99.6% conversion of H₂O₂. ► The MR gave 97% selectivity to phenol and 76.4% extraction of phenol. ► The vanadium catalyst, instead of iron catalysts, avoid tar by-product formation. ► pH 1.8 and temperature 35°C give better performance of the MR. ► Reductants (ascorbic acid & zinc) gave worse performance compared to their absence.Phenol production through the direct hydroxylation of benzene with hydrogen peroxide, as oxidant, using a vanadium catalyst in a membrane reactor has been studied. The reaction was carried out in mild condition in a liquid–liquid biphasic system separated by a polypropylene membrane. This system showed high selectivity to phenol, minimizing its over-oxidation to over-oxygenated by-products. The influence of various reaction parameters such as the addition of hydrogen peroxide mode, catalyst and sulphuric acid amounts, temperature and reducing agent effects were investigated. The vanadium catalyst avoided tar formation in all the investigated experimental conditions compared to the previous system where an iron-based catalyst was used. Use of (C₅H₈O₂)₂VO as catalyst, 18mmol of hydrogen peroxide as oxidant pumped for 4h in the aqueous phase with the step-by-step feeding mode gave the best system performance in terms of yield (63.2%), selectivity to phenol (97.0%), and extraction quotient (76.4%).

Keywords: Direct hydroxylation of benzene; Phenol production; Membrane reactor; Vanadium catalyst

Low-temperature combustion of chlorinated hydrocarbons over CeO₂/H-ZSM5 catalysts by Beatriz de Rivas; Carmen Sampedro; Rubén López-Fonseca; Miguel Ángel Gutiérrez-Ortiz; Jose Ignacio Gutiérrez-Ortiz (pp. 93-101).

.Display Omitted► CeO₂/H-ZSM5 catalysts resulted highly active in the oxidation of 1,2-dichloroethane. ► Activity was attributed to the synergetic role played by oxygen mobility and acid sites. ► This bifunctional character was optimised for the sample with a 11wt.% CeO₂ content. ► The formation of chlorinated intermediates was substantially reduced.The performance of various CeO₂/H-ZSM5 catalysts was evaluated for the oxidation of one of the most common chlorinated pollutants found in waste streams, namely 1,2-dichloroethane. The supported samples with varying CeO₂ loading (6–50wt.%) were prepared by impregnation and subsequently calcined at 550°C. Structural, morphological and physico-chemical changes caused by the CeO₂ addition were analysed by X-ray diffraction, transmission electronic microscopy, N₂-physisorption, temperature-programmed desorption of ammonia and temperature-programmed reduction with hydrogen. The enhancement of the catalytic behaviour of the resulting samples with respect to plain H-ZSM5 could be accounted for on the basis of the synergetic role played by oxygen mobility and acid sites. Hence, an optimum cerium loading of 11wt.% was found with a T₅₀ value around 210°C. At 350°C, where conversion of the chlorinated feed is about 99%, the major oxidation products were carbon oxides and hydrogen chloride with a reduced presence of chlorinated by-products and molecular chlorine. A relatively good catalytic stability was noticed during 80h time on line.

Keywords: Chlorinated VOCs; Catalytic oxidation; 1,2-Dichloroethane; Supported cerium oxide catalyst; H-ZSM5 zeolite

Evaluation of oxide catalysts’ properties based on isopropyl alcohol conversion by Wincenty Turek; Agnieszka Krowiak (pp. 102-110).

Display Omitted► Isopropyl alcohol conversion as a test reaction for surface properties of oxide catalysts. ► Simple and mixed oxides having diverse acid–base and redox properties. ► Dependence between acid–base centre strength and rates of parallel reactions. ► Test of strength and type of active centres. ► Conditions of diisopropyl ether formation over oxide catalysts.The aim of this work was to verify the usefulness of isopropyl alcohol conversion as a test reaction to evaluate the properties of the surface of oxide catalysts. The results presented below suggest that this test reaction can be used not only to distinguish the type of active centres over which the reaction proceeds but also to determine the strength of active centres. The strength of active centres can be evaluated on the basis of the rates of respective parallel reactions. The type of active centres can be determined from the rates of parallel reaction at the given temperature and selectivity of these reactions. The possibility of formation of diisopropyl ether over Lewis acid centres depends on the distance between the adjacent cations, their accessibility for reactants and the acidity.

Keywords: Oxide catalysts; Test reaction; Acid–base properties; Redox properties; Isopropyl alcohol; Dehydration; Dehydrogenation

Microwave-assisted synthesis of CdS intercalated K₄Nb₆O₁₇ and its photocatalytic activity for hydrogen production by Wenquan Cui; Yanfei Liu; Li Liu; Jinshan Hu; Yinghua Liang (pp. 111-118).

.Display Omitted► CdS intercalated K₄Nb₆O₁₇ was successfully synthesized under microwave irradiation. ► Microwave irradiation sharply shortened the intercalation procedure. ► The photocatalyst exhibited high activity for hydrogen production. ► The mechanism of charge separation in the K₄Nb₆O₁₇/CdS composites was proposed.CdS intercalated K₄Nb₆O₁₇ (designated as K₄Nb₆O₁₇/CdS) composite photocatalysts were synthesized using a microwave-assisted synthesis. The composite particles were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), X-ray fluorescence spectrometry (XRF), energy dispersive X-ray (EDS), ultraviolet–visible diffuse reflection spectra (UV–vis) and photoluminescence measurements (PL). The photocatalytic properties of these catalysts for hydrogen production were also investigated in the presence of Na₂S and Na₂SO₃ sacrificial reagents. The K₄Nb₆O₁₇/CdS catalysts synthesized using microwave irradiation were found to possess higher crystallinity than their counterparts, synthesized using conventional methods. The absorption edge of K₄Nb₆O₁₇ was shifted to the visible light region after the intercalation of CdS. Compared to the conventional synthesis method, the use of microwave irradiation sharply shortened the intercalation time. Furthermore, the K₄Nb₆O₁₇/CdS sample prepared via microwave irradiation exhibited higher activities for photocatalytic hydrogen production under both UV light and visible light irradiation, and the amounts of hydrogen produced were 265.95mmol/(gcat) and 5.68mmol/(gcat) after 3h of irradiation, respectively. The mechanism of separation of the photogenerated electrons and holes at the K₄Nb₆O₁₇/CdS composite was discussed.

Keywords: Microwave; Intercalation; CdS; K; ₄; Nb; ₆; O; ₁₇; Photocatalytisis, Hydrogen production

Correlation patterns and effect of syngas conversion level for product selectivity to alcohols and hydrocarbons over molybdenum sulfide based catalysts by Robert Andersson; Magali Boutonnet; Sven Järås (pp. 119-128).

Display Omitted► K–Ni–MoS₂ and MoS₂ catalysts for higher alcohol and hydrocarbons synthesis from syngas. ► The effect of space velocity and temperature on products selectivity was tested. ► Correlation between CO conversion and selectivity to alcohols and hydrocarbons. ► Correlation between aldehyde, alcohol and olefin selectivities. ► Correlation between alcohol chain lengths and ester chain lengths.The focus of the present study was to investigate the effect of the operation conditions, space velocity and temperature, on product distribution for a K–Ni–MoS₂ catalyst for mixed alcohol synthesis from syngas. All experiments were performed at 91bar pressure and constant H₂/CO=1 syngas feed ratio. For comparison, results from a non-promoted MoS₂ catalyst are presented. It was found that the CO conversion level for the K–Ni–MoS₂ catalyst very much decides the alcohol and hydrocarbon selectivities. Increased CO conversion by means of increased temperature (tested between 330 and 370°C) or decreased space velocity (tested between 2400 and 18,000ml/(g_cath)), both have the same effect on the product distribution with decreased alcohol selectivity and increased hydrocarbon selectivity. Increased CO conversion also leads to a greater long-to-short alcohol chain ratio. This indicates that shorter alcohols are building blocks for longer alcohols and that those alcohols can be converted to hydrocarbons by secondary reactions. At high temperature (370°C) and low space velocity (2400ml/(g_cath)) the selectivity to isobutanol is much greater than previously reported (9%C). The promoted catalyst (K–Ni–MoS₂) is also compared to a non-promoted (MoS₂) catalyst; the promoted catalyst has quite high alcohol selectivity, while almost only hydrocarbons are produced with the non-promoted catalyst. Another essential difference between the two catalysts is that the paraffin to olefin ratio within the hydrocarbon group is significantly different. For the non-promoted catalyst virtually no olefins are produced, only paraffins, while the promoted catalyst produces approximately equal amounts of C₂–C₆ olefins and paraffins. Indications of olefins being produced by dehydration of alcohols were found. The selectivity to other non-alcohol oxygenates (mostly short esters and aldehydes) is between 5 and 10%C and varies little with space velocity but decreases slightly with increased temperature. Very strong correlation patterns (identical chain growth probability) and identical deviations under certain reaction conditions between aldehyde and alcohol selectivities (for the same carbon chain length) indicate that they derive from the same intermediate. Also olefin selectivity is correlated to alcohol selectivity, but the correlation is not as strong as between aldehydes and alcohols. The selectivity to an ester is correlated to the selectivity to the two corresponding alcohols, in the same way as an ester can be thought of as built from two alcohol chains put together (with some H₂ removed). This means that, e.g. methyl acetate selectivity (C₃) is correlated to the combination of methanol (C₁) and ethanol (C₂) selectivities.

Keywords: Syngas; Higher alcohols; MoS; ₂; Synthetic fuels

Cooperative effect of gold nanoparticles with CUS aluminium from nanoalumina support in the catalysis of an electron transfer reaction by Fereshteh Rashidi; Enrique Lima; Hassan Rashidi; Alimorad Rashidi; Ariel Guzmán (pp. 129-136).

Display Omitted► Nanorod mesoporous gamma and alpha-alumina with high surface area (630m²g⁻¹). ► Preparation of nanogold catalysts supported on various nanostructured alumina. ► Redox reaction catalysis of iron ferrocyanide by nanogold/nanoalumina catalysts. ► Highly and uniformly nanogold dispersion on the high surface area nanoalumina. ► Controlling of activity and acidity of nanogold catalysts by nanoalumina properties.In this paper, firstly mesoporous gamma and alpha-alumina with nanorod morphology, exhibiting high surface area (629.44m²g⁻¹), large pore volume (2.25cm³g⁻¹) and pore size (140.3Å) have been synthesised by a non-surfactant-templating sol–gel method. Then, new nanocatalysts, i.e. Au-NAl350, Au-NAl550, Au-NAl750, and Au-NAl1100 were prepared by deposition of gold nanoparticles on the various synthesised nanostructured alumina supports with different physicochemical properties; surface area (20.56–629.44m²g⁻¹), pore volume (0.63–2.25cm³g⁻¹) and pore size (73.88–143.76Å). Textural, morphological and structural characterisations of both nanoalumina supports and nanogold/nanoalumina catalysts were done by nitrogen physisorption, XRD,²⁷Al MAS NMR, TEM and FTIR study of low temperature CO-adsorption. The effect of physiochemical properties of the nanoalumina supports on the structure and catalytic activity of nanogold active phase were studied in the catalytic reduction of ferricyanide to ferrocyanide by thiosulphate under three reaction temperature; 20, 40 and 60°C. It was found that the Au-NAl550 nanocatalyst with large surface area (579m²g⁻¹), pore volume (2.13cm³g⁻¹) and pore size (141.05Å) has the highest catalytic activity. The characterisation results showed that Au nanoparticles highly and uniformly dispersed on the high surface area nanoalumina support. The metallic character of the gold nanoparticles, acidity and activity of catalyst were determined by structure, acidity and texture of the nanoalumina support. It was confirmed that the reduction reaction is totally controlled by the surface properties of catalyst.

Keywords: Nanogold catalysis; Adsorption; Nanoalumina; Acidity; Reduction

Conversion of ethanol to propylene over HZSM-5(Ga) co-modified with lanthanum and phosphorous by Yoshiyasu Furumoto; Nao Tsunoji; Yusuke Ide; Masahiro Sadakane; Tsuneji Sano (pp. 137-144).

.Display Omitted► HZSM-5(Ga) co-modified with lanthanum and phosphorous was prepared. ► High propylene yield of ca. 29 C-% was obtained at a P/Ga ratio of 1 and a La/Ga ratio of 0.4. ► Co-modification was very effective for improvement of the catalytic activity and stability of HZSM-5(Ga).Conversion of ethanol to propylene was carried out over HZSM-5(Ga) co-modified with lanthanum and phosphorous (La/P/HZSM-5(Ga)). The propylene yield was strongly dependent on both the La/Ga and P/Ga ratios, and the highest value of ca. 29 C-% was obtained at a P/Ga ratio of 1 and a La/Ga ratio of 0.4. FT-IR,³¹P MAS NMR, and⁷¹Ga MAS NMR measurements demonstrate that the introduced lanthanum reacts with the pre-introduced phosphorous to regenerate some of Brønsted acid sites (Si(OH)Ga), and accordingly, the Brønsted acid sites are homogeneously distributed within the zeolite framework. In addition, the catalytic stability as well as the catalytic activity of HZSM-5(Ga) was effectively enhanced by co-modification with lanthanum and phosphorous because of the suppression of carbonaceous deposition and elimination of gallium from the zeolite framework.

Keywords: Ethanol; Propylene; ZSM-5; Phosphorous; Lanthanum

Comparison of oxidizing agents for the oxidative coupling of methane over state-of-the-art catalysts by Kirsten Langfeld; Benjamin Frank; Verena E. Strempel; Claudia Berger-Karin; Gisela Weinberg; Evgenii V. Kondratenko; Reinhard Schomäcker (pp. 145-152).

Display Omitted► Besides chemical composition the synthesis strategy is a crucial factor for success in terms of high C₂ yields. ► High surface areas obtained with the cellulose templating method are detrimental to C₂ selectivity. ► Catalyst recipes and trends in catalytic performances reported in literature can be reproduced in most cases. ► N₂O is a milder oxidizing agent than O₂ leading to lower CH₄ conversions and higher C₂ selectivities even at iso-conversion. ► CO₂ activation requires high temperatures although thermodynamically favored.The synthesis of selected state-of-the-art catalysts providing high performances in the oxidative coupling of methane (OCM) with O₂ was reproduced according to the respective recipes reported in literature. A reference material with identical stoichiometric composition was further synthesized by applying the cellulose templating method. This method increases the surface area and affects the phase composition and crystallite size of the catalysts as determined by N₂-physisoprtion, X-ray diffraction and scanning electron microscopy. This, however, is in most cases detrimental to the catalytic OCM performance due to enhanced global activity resulting in hot spots in the catalyst bed. Catalysts were tested in the OCM under variation of temperature (973–1073K), GHSV (3600–100,000h⁻¹) and oxidizing agent (O₂ and N₂O). In general, conversions of CH₄ when using N₂O are lower than in the presence of O₂, however, the selectivities to C₂ products ethane and ethylene are higher even at a similar level of CH₄ conversion. This confirms the presence of different oxygen species formed by activation of these oxidizing agents.

Keywords: C–H activation; Oxygen; Nitrous oxide; Cellulose templating; Deactivation

Oxidative dehydrogenation of propane over cobalt-containing mixed oxides obtained from LDH precursors by Gheorghiţa Mitran; Thomas Cacciaguerra; Stéphane Loridant; Didier Tichit; Ioan-Cezar Marcu (pp. 153-162).

.Display Omitted► Cobalt-containing layered double hydroxides as mixed oxide catalyst precursors. ► Catalysts for propane oxidative dehydrogenation. ► Activity increased with the cobalt content and the reducibility of the catalysts. ► Higher propene selectivity was obtained at lower cobalt content. ► The well-dispersed Co species played a key role in propane oxidative dehydrogenation.Co( x)MgAlO mixed oxide catalysts with cobalt content in the range from 1 to 20at.%, were prepared by calcination of layered double hydroxide (LDH) precursors at 1023K. Their characterization was performed using X-ray diffraction (XRD), energy-dispersive X-ray spectroscopy (EDX), N₂ adsorption, Raman and photoluminescence spectroscopies, TG–DTG and H₂-TPR techniques. The catalytic activities were evaluated in the oxidative dehydrogenation of propane in the temperature range from 723 to 873K. For all the catalysts the conversion increased when the reaction temperature increased, while the propene selectivity decreased continuously to the benefit of CO_x for Co(20)MgAlO and Co(10)MgAlO catalysts and of cracking products for the other cobalt-containing catalysts. In all the temperature range studied, the catalytic activity increased with increasing the cobalt content in the catalyst in line with the increase of reducibility. The best yields in propene of about 10% were obtained with Co(5)MgAlO and Co(7)MgAlO catalysts for the reaction performed at 873K. Besides, a comparison of the behavior of Co(3)MgAlO and Co(7)MgAlO catalysts at 823K showed that, at isoconversion, the propene selectivity was higher for the sample with lower cobalt content. The well-dispersed cobalt species with tetrahedral coordination played a main role in the oxidative dehydrogenation reaction of propane into propene. When the propane-to-oxygen molar ratio was increased from 1 to 4, the conversion decreased while propene selectivity increased continuously and the best propene yields were obtained for a propane-to-oxygen molar ratio of 1.

Keywords: Co-containing oxides; Layered double hydroxides; Propane; Oxidative dehydrogenation

Catalysed ethylbenzene dehydrogenation in CO₂ or N₂—Carbon deposits as the active phase by Christian Nederlof; Freek Kapteijn; Michiel Makkee (pp. 163-173).

Display Omitted► Bare alumina support becomes active during operation under reaction conditions. ► Alumina increases conversion and selectivity up to 60% and 93%, respectively. ► Deactivation of the catalyst remains the largest issue to be solved. ► Formed carbon selectively poisons highly active and unselective sites.Bare alumina support transforms into an active catalyst for the dehydrogenation of ethylbenzene to styrene in CO₂ or N₂. During the first 15h time on stream in CO₂, or the first 10h time on stream in N₂, the alumina shows an increase in ethylbenzene conversion and styrene selectivity from 15% to 60% and from 60% to 92%, respectively, under industrially relevant conditions of 600°C and 10vol% ethylbenzene. Thereafter, the system slowly deactivates, but remains highly selective. TGA analysis shows an increase in coke content. The specific surface area and pore volume show a decrease with time on stream. TEM-imaging reveals that the spent catalyst surface is completely covered by several layers of coke. These results combined suggest that the carbon deposits on the alumina are responsible for the increase in activity and selectivity, and also are the cause of deactivation once a monolayer of carbon is deposited on the support surface. Similar trends are observed for zirconia support. Supported vanadium and chromium oxides on alumina all give similar results, but after a faster activity development. Also for these supported catalysts and even carbon samples, deposited coke is the active and selective phase.

Keywords: Dehydrogenation; Carbon dioxide; Nitrogen; Ethylbenzene; Styrene; Carbon deposits; Coke; Alumina; Zirconia

Kinetic studies of carbon nanofibre and hydrogen evolution via ethane decomposition over fresh and steam regenerated Ni/La₂O₃ catalyst by Shahrbanoo Rahman Setayesh; Kenneth C. Waugh (pp. 174-182).

Display Omitted► The co-precipitated Ni/La₂O₃ as catalyst for stepwise steam reforming of ethane. ► NiO, LaNiO₃, and La₂O₃ phases are present in catalyst. ► The similar TPRn spectra and initial activity toward ethane decomposition for four times. ► Steam gasification can be as potential routes for the regeneration of Ni/La₂O₃ catalyst. ► Ni/La₂O₃ catalyst could be a good candidate for use as a steam reforming catalyst.The co-precipitated Ni/La₂O₃ catalyst had low total surface area and adsorption–desorption isotherm of nearly type II. The X-ray diffractogram demonstrates that NiO, LaNiO₃, and La₂O₃ were the phases present in Ni/La₂O₃ catalyst. The decomposition of ethane over Ni/La₂O₃ catalyst has been investigated using temperature-programmed reaction (TPRn). TPRn profile exhibited both low temperature and high temperature range of carbon deposition and indicated the production of H₂ and CH₄ in the gas phase from decomposition of ethane. Methane may be evolved from hydrogenation of surface methyl group from the decay of ethylidyne intermediate. The content, type of carbon, and kinetics of reaction of carbon with oxygen were determined by using temperature-programmed oxidation (TPO). Succeeding the regeneration of Ni/La₂O₃ catalyst after carbon deposition for three times with steam, this catalyst exhibited the similar TPRn spectra and had still initial activity toward ethane decomposition and carbon nanofibres production. Results of isothermal gasification of carbon nanofibres with steam at temperatures of 823–923K showed that most of the carbon nanofibres are removed during reaction with steam.

Keywords: Co-precipitated Ni/La; ₂; O; ₃; catalyst; Carbon nanofibres; Ethylidyne; Stepwise steam reforming of ethane; Regeneration of Ni/La; ₂; O; ₃; catalyst by steam

One-pot fabrication of magnetically recoverable acid nanocatalyst, heteropolyacids/chitosan/Fe₃O₄, and its catalytic performance by Aiguo Kong; Ping Wang; Hengqiang Zhang; Fan Yang; SongPing Huang; Yongkui Shan (pp. 183-189).

Display Omitted► One-pot fabrication of magnetically recoverable nanocatalyst, heteropolyacids/chitosan/Fe₃O₄. ► Immobilization of the heteropolyacids on superparamagnetic iron oxides with alkalescence. ► A magnetically recoverable acid nanocatalyst with high activity for the acetalization reactions.A magnetically recoverable acid nanocatalyst, heteropolyacids/chitosan/Fe₃O₄ (HSiW-CS-Fe₃O₄), was successfully prepared by a one-pot synthesis method. The characterized results by XRD, TEM, TGA, FT-IR and magnetic measurements testified that Keggin-type 12-silicotungstic acid (HSiW) was efficiently immobilized into the cross-linked chitosan (CS) coating on nanometer-sized Fe₃O₄ magnetic cores. The prepared HSiW-CS-Fe₃O₄ possesses a typical superparamagnetic behavior and has the acid capacity of 0.13mmol/g. It exhibits higher catalytic activity in the acetalization reaction of benzaldehyde with ethylene glycol, and gives a 99% yield for acetal under mild reaction conditions. Furthermore, the prepared catalysts can be magnetically separated from the reaction system and reused 5 times without the significant loss of catalytic activities. It is also confirmed that the recovered catalysts are not dramatically changed in the physicochemical features. The prepared HSiW-CS-Fe₃O₄ may be the promising catalytic material in a mass production of the fine chemicals.

Keywords: Magnetic separation; Chitosan; Heteropolyacids; Acid catalyst; Acetalization

IR study of iridium bonded to perturbed silanol groups of Pt-HZSM5 for n-pentane isomerization by Herma Dina Setiabudi; Aishah Abdul Jalil; Sugeng Triwahyono; Nur Hidayatul Nazirah Kamarudin; Rino R. Mukti (pp. 190-199).

Display Omitted► Iridium in the form of IrO₂ bonded with perturbed silanol groups. ► Iridium did not change the lattice structure of HZSM5. ► Iridium increased the number of Brönsted and Lewis acid sites ► Iridium did not interact with terminal SiOH group or Si(OH)Al group. ► Iridium increased iC₅ selectivity and suppressed C₁–C₄ cracking products.The Ir/Pt-HZSM5 catalyst was prepared by impregnation of iridium on Pt-HZSM5. The activity of Ir/Pt-HZSM5 was tested for n-pentane isomerization under hydrogen stream. The introduction of iridium did not change the bands observed at 3740, 3665 and 3610cm⁻¹ indicating that neither non-acidic terminal silanol groups nor acidic bridging hydroxyl groups interacted with the iridium. Additionally, the peaks corresponding to the perturbed silanol groups at 3700 and 3520cm⁻¹ decreased significantly. X-ray photoelectron spectroscopy (XPS) analysis revealed that the iridium is in the form of IrO₂.²⁷Al MAS NMR confirmed the elimination of distorted tetrahedral aluminum. The presence of iridium slightly increased the acidity of Pt-HZSM5 and its selectivity for iso-pentane. Hydrogen adsorption FTIR indicated that iridium enhanced the formation of protonic acid sites which may participate in the isomerization, and inhibited the formation of hydroxyl groups at 3380, 3600 and 3680cm⁻¹ which may participate in the enhancement of the cracking reaction.

Keywords: IrO; ₂; Ir/Pt-HZSM5; Perturbed silanol groups; Protonic acid sites; n; -Pentane isomerization

Sodium hypophosphite and nano TiO₂ inorganic catalysts along with citric acid on textile producing multi-functional properties by S. Hashemikia; M. Montazer (pp. 200-208).

TGA curves of samples 1, 2, 5, 6 and control.Display Omitted► Using sodium hypophosphite/nano TiO₂/citric acid producing textile with multi-functional properties. ► Applying friendly cross-linker to obtain durable properties on textile. ► Using available and cost effective materials in simple application to produce textile with diverse features. ► Introducing cotton/polyester knitted fabric with reasonable multi-functional properties.Nowadays, introducing a textile with multi-functional properties is in a central point of research also application of nano particles can be helpful to reach this goal. Here, nano TiO₂, citric acid and sodium hypophosphite applied on the cotton/polyester knitted fabric to obtain divers features on the fabric. The results revealed an excellent performance of the treatment on diverse properties of the fabric including flame retardancy, anti-pilling, hydrophilicity, self-cleaning, antibacterial and UV protection properties. Increasing the concentration of CA enhanced both the photoactive properties and washing fastness of the TiO₂ treated fabrics. Thermal behaviors of the treated fabrics displayed flame retardant characteristics with high char residue. Also the treated fabrics indicated the higher bioactivity and hydrophilicity with considerable lower pilling rate. This paper revealed a simple method on application of inorganic catalysts with friendly cross-linking agent to introduce multi-functional properties in the blended fiber yarns with knitted structure.

Keywords: Sodium hypophosphite; Nano TiO; ₂; Citric Acid; Cotton/polyester; Multi-functional

Optimization of the preparation procedure of cobalt modified silicas as catalysts in methanol decomposition by Tanya Tsoncheva; Alessandro Gallo; Nicola Scotti; Momtchil Dimitrov; Romain Delaigle; Eric M. Gaigneaux; Daniela Kovacheva; Vladimiro Dal Santo; Nicoletta Ravasio (pp. 209-219).

Display Omitted► Novel chemisorption–hydrolysis method for loading of cobalt on mesoporous silicas. ► Wetness impregnation facilitates formation of finely dispersed Co₃O₄ particles. ► Chemisorption–hydrolysis produces strongly interacted with the support species. ► Successful control of cobalt phase composition by varying chemisorption procedure. ► Under reduction medium pore topology of silica strongly affects catalytic activity.Novel modified “chemisorption–hydrolysis” technique and conventional “incipient wetness impregnation” procedure were compared for loading of cobalt species on mesoporous silica supports. Effect of cobalt amount, pH of the precursor solution, duration of the “chemisorption” procedure and pre-treatment medium, as well as topological characteristics of the mesoporous silica support were investigated. The state of the loaded cobalt species was studied by XRD, FTIR, FTIR of adsorbed pyridine, UV–vis, XPS and TPR methods and their catalytic properties were elucidated in methanol decomposition to hydrogen and carbon monoxide. The “incipient wetness impregnation” technique facilitates the formation of finely dispersed spinel cobalt oxide species. Their catalytic activity could be significantly increased by hydrogen pretreatment, but the effect is more pronounced when mesoporous silica with ordered pseudo 1D pore structure (SBA-15) is used as a support. The modified “chemisorption–hydrolysis” procedure facilitates the formation of strongly interacting with the support cobalt species, which are stable under the reduction conditions. Their properties could be regulated during the modification procedure, by varying the cobalt content and pH of the impregnated solution as well as by the duration of the “chemisorption” procedure.

Keywords: SBA-15; KIT-6; Cobalt modifications; Post-synthesis modification; Pore topology effect; Methanol decomposition

Steam catalytic cracking of naphtha over ZSM-5 zeolite for production of propene and ethene: Micro and macroscopic implications of the presence of steam by Avelino Corma; Jesús Mengual; Pablo J. Miguel (pp. 220-235).

Display Omitted► Steam causes an irreversible and a reversible loss of activity in cracking process. ► The apparent activation energy is lower with steam caused by a selective interaction. ► Catalyst deactivation can be reproduced by a model with two deactivation processes. ► High reaction temperatures strongly favour the yields of ethene and propene. ► Steam has an inhibiting effect on protolytic cracking and recracking.One option to produce more ethene and propene can be to crack naphtha type fractions in dedicated smaller FCC units. We present here the results obtained for high temperature steam catalytic cracking (SCC) of a representative naphtha product ( n-heptane) with ZSM-5. It has been found that under those conditions the presence of steam produces an irreversible dealumination of the zeolite as well as a reversible deactivation due to the interaction of water with active sites with a negative effect on protolytic cracking. A kinetic decay model that takes into account the two phenomena has been developed. The apparent activation energy is lower in the presence of steam. It appears that whilst the presence of steam is vital when processing heavy feeds to achieve a better feed dispersion and a more effective catalytic cracking in conventional fluid catalytic cracking (FCC) units, in the case of steam catalytic cracking of naphtha ( n-heptane) the presence of steam has a negative effect on the final performance of the catalyst. On the other hand, whilst steam does not modify ethene and propene selectivity, significantly decreases H₂ and CH₄ formation, as well as formation of potential coke precursors.

Keywords: Steam catalytic cracking (SCC); Production of ethene and propene by catalytic cracking; Steam catalytic cracking of naphtha; Steam deactivation of ZSM-5

Cu-doped zeolites for catalytic oxidative carbonylation: The role of Brønsted acids by Shouying Huang; Yue Wang; Zengzhu Wang; Bing Yan; Shengping Wang; Jinlong Gong; Xinbin Ma (pp. 236-242).

.Display Omitted► Nature of Brønsted acidic sites in Cu-doped zeolites was investigated. ► A quantitative relationship was drawn between Brønsted sites and reactivity. ► Effects of Brønsted acidic sites on anchoring Cu sites were examined.The aim of this work was to establish the role of Brønsted acidic sites in Cu-doped zeolites for the oxidative carbonylation of ethanol to diethyl carbonate (DEC). In order to eliminate the influences of other factors such as channel structure, faujasite (FAU) with different SiO₂/Al₂O₃ ratios and Beta before and after passivation were investigated. Fourier Transform infrared spectroscopy (FTIR) of pyridine adsorption indicated that all of Brønsted acidic sites were exchanged with CuCl to form effective active sites for oxidative carbonylation. Characterization data showed that passivation on Beta zeolites has little effect on surface area and pore volume distribution except Brønsted acidic sites. The relationship between Brønsted acidic sites and catalyst activity was built on different types of zeolite supports. Diffuse reflectance infrared Fourier transform spectroscopy (DIRFTS) of CO adsorption revealed that the location of Cu active sites was related to the distribution of Brønsted acidic sites, which also influenced catalytic performance of oxidative carbonylation.

Keywords: Oxidative carbonylation; Cu-doped zeolite; Brønsted acids; Dialkyl carbonate

Aqueous-phase dehydration of xylose to furfural in the presence of MCM-22 and ITQ-2 solid acid catalysts by Margarida M. Antunes; Sérgio Lima; Auguste Fernandes; Martyn Pillinger; Maria F. Ribeiro; Anabela A. Valente (pp. 243-252).

Display Omitted► H-MCM-22 and ITQ-2 are effective catalysts in aqueous phase dehydration of xylose to furfural. ► H-MCM-22 and ITQ-2 give similar catalytic results to the industrial catalyst H₂SO₄. ► Recyclable solid acids with no structural modifications or leaching phenomena detected.The H-MCM-22 zeolite possessing an MWW (medium-pore) framework and its delaminated counterpart, ITQ-2, with enhanced external surface area, are effective and recyclable solid acid catalysts in the batch-wise, aqueous-phase dehydration of xylose, at 170°C. Up to 71% furfural (Fur) yield is reached at 98% conversion using a biphasic aqueous–organic solvent system (for the simultaneous extraction of Fur); using solely water as the solvent gives up to 54% Fur yield at 97% conversion. Sulfuric acid, used in an approximately equivalent amount to the total acid site concentration of the solid acids, gave 55% Fur yield at 93% conversion. Decreasing the Si/Al ratio of H-MCM-22 zeolite improves the acid properties and consequently the catalytic activity, without affecting significantly the Fur selectivity. While the delamination process considerably enhanced the external surface area of ITQ-2 in comparison to H-MCM-22, it caused modifications in the acid properties, leaving the two prepared materials with the same Si/Al atomic ratio of 24, on a comparable footing in terms of catalytic performance in the studied catalytic reaction. Nevertheless, these solid acid catalysts are fairly stable (similar Fur yields are reached in recycling runs; no structural modifications and no leaching phenomena were detected).

Keywords: Xylose; Furfural; Acid dehydration; MCM-22 zeolite; ITQ-2

Photodecolourization of orange II with iron corrosion products and oxalic acid in aqueous solution by Shouqiang Wei; Long Liu; Haibo Li; Jing Shi; Ying Liu; Zhongcai Shao (pp. 253-258).

Display Omitted► Iron corrosion products were evaluated as heterogeneous catalysts. ► An economically viable system for decolourization of orange II was developed. ► Factors affecting decolourization efficiency for this system were examined.Iron corrosion products (ICPs) were tested as heterogeneous catalysts to decolourize orange II (OII) in the presence of oxalic acid under simulated natural light or solar light. ICPs were collected from the cast iron pipes used in a wastewater treatment plant, and characterized with energy dispersive X-ray spectroscopy (EDS), X-ray powder diffraction (XRD) and N₂ adsorption/desorption isotherm analyses. The photodecolourization efficiency depends significantly on various factors including the ICPs dosage, initial concentration of oxalic acid and the initial pH value. Under the optimal conditions (ICPs dosage 0.40g/L, initial concentration of oxalic acid 1.6mM and pH 3.0), the photodecolourization efficiency for a solution of 25mL containing 10mg/L OII reaches 83% and 44%, respectively, under simulated natural light ( I=14mW/cm²) and solar light ( I=1.2mW/cm²) for 30min. Tartaric or citric acid is also efficient for ICPs to photodecolourize OII under simulated natural light. Since this system directly uses ICPs as heterogeneous catalysts and does not require the addition of hydrogen peroxide and shows good efficiency even under solar light, it is an economically viable method for decolourization of wastewaters containing dyes.

Keywords: Iron corrosion products; Iron oxides; Oxalic acid; Photo-Fenton-like system; Photodecolourization; Orange II

Aryl sulfonic acid catalyzed hydrolysis of cellulose in water by Ananda S. Amarasekara; Bernard Wiredu (pp. 259-262).

Display Omitted► Aryl sulfonic acids are better catalysts than H₂SO₄ for hydrolysis of cellulose. ► 4-Biphenylsulfonic acid gave the highest glucose yield at160°C. ► Catalytic activity correlates with log D of the sulfonic acids.Catalytic activities of eight alkyl/aryl sulfonic acids in water were compared with sulfuric acid of the same acid strength (0.0321mol H⁺ ion/L) for hydrolysis of Sigmacell cellulose (DP∼450) in the 140–190°C temperature range by measuring total reducing sugar (TRS), and glucose produced. Cellulose samples hydrolyzed at 160°C for 3h, in aqueous p-toluenesulfonic acid, 2-naphthalenesulfonic acid, and 4-biphenylsulfonic acid mediums produced TRS yields of 28.0, 25.4, and 30.3% respectively, when compared to 21.7% TRS produced in aqueous sulfuric acid medium. The first order rate constants at 160°C in different acid mediums correlated with octanol/water distribution coefficient log D of these acids, except in the case of highly hydrophobic 4-dodceylbenzenesulfonic acid. In the series of sulfonic acids studied, 4-biphenylsulfonic acid appears to be the best cellulose hydrolysis catalyst.

Keywords: Cellulose; Hydrolysis; Sulfonic acids; Saccharification; Catalyst

Hydrogen photoproduction under visible irradiation of Au–TiO₂/activated carbon by Juan Matos; Tiziana Marino; Raffaele Molinari; Hermenegildo García (pp. 263-272).

Hydrogen photoproduction under Au–TiO₂/AC.Display Omitted► Au–TiO₂/activated carbon materials for H₂ photoproduction under visible light. ► Photo-assistance of carbon materials to TiO₂. ► Enhancement in the surface plasmon resonance of Au nanoparticles.The photoproduction of hydrogen has been performed under visible light irradiation of Au–TiO₂/activated carbon (AC) materials prepared by different activation methods. Results were compared against those obtained under ultraviolet irradiation. Characterization of TiO₂, AC and Au–TiO₂/AC was performed by adsorption–desorption N₂ isotherms, surface pH (pH_PZC), infrared spectroscopy (FTIR), X-ray diffraction (XRD), X-ray photoelectronic spectroscopy (XPS), diffuse reflectance UV–vis spectroscopy (DR/UV–vis), and transmission electron microscopy (TEM). The present results showed that functional groups on the carbon surface are responsible to enhance 2.6 times the photocatalytic activity of Au nanoparticles deposited on TiO₂. Characterization suggests that carboxylate anions detected on surface of some AC interact with metallic center at TiO₂ and this surface interaction would be responsible of the enhancement in the photoactivity.

Keywords: H; ₂; photoproduction; TiO; ₂; Au-based catalysts; Activated carbon

Preparation, characterization and use of V₂O₅-TiO₂ mixed xerogels as catalysts for sustainable oxidation with hydrogen peroxide of 2,3,6-trimethylphenol by Magdalena Palacio; Paula I. Villabrille; Gustavo P. Romanelli; Patricia G. Vázquez; Carmen V. Cáceres (pp. 273-280).

Display Omitted► V₂O₅-TiO₂ mixed xerogels were prepared by the sol–gel method. ► They were tested in the liquid phase oxidation of 2,3,6-trimethylphenol with H₂O₂. ► For catalyst with 5% V, 90% conversion and 99% selectivity were observed at 4h ► A radical mechanism for reaction was proposed ► Different substituted phenols were also tested in the oxidation reaction.V₂O₅-TiO₂ mixed xerogels were prepared with different loads of TiO₂ and V₂O₅ (5%, 10%, 15% V₂O₅ w/w) by the sol–gel method using titanium isopropoxide and vanadyl acetylacetonate as precursors. The solids obtained were characterized by XRD, FT-IR and SEM. Their textural properties were determined by adsorption–desorption isotherms of N₂ at 77K. Also the acidity of the catalysts was measured by means of potentiometric titration with a solution of n-butylamine in acetonitrile.The catalysts were tested in the liquid phase oxidation of 2,3,6-trimethylphenol (2,3,6-TMF) to 2,3,5-trimethyl- p-benzoquinone (2,3,5-TMBQ) at 20°C, using ethanol as solvent and aqueous hydrogen peroxide as clean oxidizing agent. The conversion increases with time to reach at 3h a plateau of 93% and 88% for the samples without V and with 5% of V respectively. An increase of the V concentration to 10% leads to a conversion value of only 22% at 4h of reaction. However, the selectivity to 2,3,5-TMBQ increases with the V content in the catalyst. The stability and leaching of catalysts and the influence of the xerogel calcination temperature were also studied. By reusing the same catalyst sample with 5% of V, a difference of 5% in the selectivity values between use and reuse was observed. A decrease from 88% to 8% of 2,3,6-TMP conversion for 4h of reaction, when the calcination temperature of xerogel increased from 200°C to 400°C, was observed. When t-butanol was added as radical scavenger, the oxidation was strongly suppressed. This makes it possible to propose a radical mechanism for 2,3,6-trimethylphenol oxidation.Substrates with different substitutes in phenol were also tested in the oxidation reaction. The substrates with methyl groups are the most actives and in the cases of thymol and carvacrol with isopropyl groups, the conversion is lower.

Keywords: V2O5-TiO2; Mixed xerogels; Oxidation catalysts; Hydrogen peroxide; 2,3,6-Trimethylphenol

Steam reforming of acetic acid over Ni/ZrO₂ catalysts: Effects of nickel loading and particle size on product distribution and coke formation by Zhikun Li; Xun Hu; Lijun Zhang; Shaomin Liu; Gongxuan Lu (pp. 281-289).

Display Omitted► Ni loading significantly affects reducibility and particle size of Ni species in Ni/ZrO₂. ► Ni (16wt.%)/ZrO₂ catalyst presents the superior catalytic activity, selectivity and stability. ► Ni (≤13wt.%)/ZrO₂ shower higher selectivity to the organic by-products. ► Ni (≥20wt.%)/ZrO₂ catalysts favor production of CO, CH₄ and the coke formation.Steam reforming of acetic acid has been carried out over a series of Ni/ZrO₂ catalysts to measure the effects of nickel loading on distribution of the reforming products and coke formation. Ni (≤13wt.%)/ZrO₂ catalysts do not contain enough active metal sites for steam reforming of both acetic acid and organic by-products. Ni (≥20wt.%)/ZrO₂ catalysts can effectively catalyze steam reforming but lack selectivity, since methanation and reverse water gas shift reactions are promoted, leading to low hydrogen yields. Ni (16wt.%)/ZrO₂ catalyst is the most selective one, due to its low activity to the secondary reactions that contribute to by-product production. Coke formation is suppressed with the increase of nickel loading up to 16wt.%, and then restarts to increases with the further increase of nickel loading. Polymerization of acetone is the main route for coke deposition over the Ni (≤13wt.%)/ZrO₂ catalysts. Methane decomposition and CO disproportion are the two main routes for coke formation over the Ni (≥20wt.%)/ZrO₂ catalysts, and methane contributes more to coke formation than CO. In addition, activity of Ni/ZrO₂ catalyst towards the secondary reactions such as methanation, reverse water gas shift reaction, methane decomposition, and CO disproportion are closely related to nickel loading and nickel particle sizes.

Keywords: Acetic acid; Steam reforming; Ni/ZrO; ₂; catalyst; Nickel loading; Coke formation

Conversion of methanol to hydrocarbons over conventional and mesoporous H-ZSM-5 and H-Ga-MFI: Major differences in deactivation behavior by Uffe V. Mentzel; Karen T. Højholt; Martin S. Holm; Rasmus Fehrmann; Pablo Beato (pp. 290-297).

Display Omitted► Methanol is converted over conventional and mesoporous H-ZSM-5 and H-Ga-MFI. ► The rate of coke formation during conversion of methanol is very low for H-Ga-MFI. ► The H-ZSM-5 based zeolites deactivate through coke deposition. ► The gallium based zeotypes deactivate through steaming rather than coke deposition.Methanol has been converted to hydrocarbons over conventional and mesoporous H-ZSM-5 and H-Ga-MFI. The gallium based zeotypes are analogous to H-ZSM-5, but the Brønsted acidity is introduced by framework incorporation of gallium rather than aluminum, which leads to lower intrinsic acid strength. In the methanol-to-hydrocarbons (MTH) process, H-ZSM-5 is subjected to coke formation leading to catalyst deactivation. Here we show that when the gallium containing zeotypes are employed in the MTH process, only insignificant amounts of coke are present in the deactivated catalysts, indicating distinct differences in deactivation mechanisms of the two different catalysts. This is investigated further through FT-IR measurements as well as catalytic experiments employing regenerated and steamed catalysts. From this it is concluded that the H-Ga-MFI is subjected to irreversible deactivation by steaming (hydrolysis) of the GaO bonds in the zeolite structure rather than coke deposition.

Keywords: Zeolite; Gallium; Methanol-to-hydrocarbons (MTH); Deactivation; Regeneration

Modification of the catalytic properties of MoO2−_x(OH)_y dispersed on TiO₂ by Pt and Cs additives by H. Al-Kandari; A.M. Mohamed; F. Al-Kharafi; M.I. Zaki; A. Katrib (pp. 298-305).

Display Omitted► Partial reduction by hydrogen of MoO₃ deposited on TiO₂ produces bifunctional MoO2−_x(OH) y phase. ► Surface XPS–UPS, ISS and FT-IR techniques were employed to characterize this structure. ► Monofuctional (metallic) phase is obtained following Cs addition to MoO₃. ► Catalytic reactions of 1-heptene, n-heptane and methylcyclohexane were carried out.Addition of 5% Pt or alkali metals such as K or Cs each separately to the bifunctional MoO2−_x(OH)_y catalyst results in modification of the chemical structure of this system, especially in the case of alkali metals. A new MoO2−_x(OA)_y, AK, Cs, monofunctional structure having only metallic properties is formed. In the case of Cs for example, the MoOCs bond formation takes place in the course of the reduction process of MoO₃ to MoO₂ by hydrogen hinders the acidic BrØnsted MoOH formation, which usually is formed in this system. Characterization by surface XPS–UPS, ISS and FT-IR spectroscopic techniques as well as catalytic activity carried out at the same experimental conditions confirm the presence of this monofunctional MoO2−_x(OCs)_y system. On the contrary, platinum addition enhances the metallic character of the MoO2−_x(OH)_y bifunctional system in terms of slight improvement in the conversion of 1-heptene and n-heptane as well as dehydrogenation of methylcyclohexane to toluene.

Keywords: Catalytic properties of MoO; 2−; _x; (OH); _y; MoO; 2−; _x; (OCs); _y; XPS; UPS; ISS; FT-IR; MoO; ₃; Pt; Cs; TiO; ₂; Bifunctional catalyst; 1-Heptene; n-Heptane; Methylcyclohexane

Effect of iron oxide on isobutane dehydrogenation over Pt/Fe₂O₃-Al₂O₃ catalyst by Shingo Kobayashi; Shinji Kaneko; Masa-aki Ohshima; Hideki Kurokawa; Hiroshi Miura (pp. 306-312).

.Display Omitted► Dehydrogenation of isobutane was remarkably improved by the addition of Fe₂O₃ to Pt/Al₂O₃. ► Formation of Pt-Fe particles increased the electron density of Pt, as revealed by FT-IR of CO. ► Addition of Fe₂O₃ inhibited sintering of supported Pt particles. ► Pt-Sn/Fe₂O₃-Al₂O₃ is a novel and excellent dehydrogenation catalyst system.The effect of adding Fe₂O₃ to an Al₂O₃-supported Pt catalyst on isobutane dehydrogenation was studied. Catalytic activity, catalyst stability, and selectivity to isobutene were improved significantly by adding a small amount of Fe₂O₃ to Pt/Al₂O₃. The catalysts were characterized by CO and NH₃ chemisorption measurements, Fourier transformed-infrared (FT-IR) analysis of adsorbed CO, and thermogravimatric-differential thermal analysis (TG-DTA) of the used catalyst. FT-IR analysis of the adsorbed CO showed that the electron density of Pt was increased by the formation of bimetallic particles. CO chemisorption suggested the formation of Pt-Fe bimetallic particles partially covered with Fe species. Furthermore, the number of strong acid sites on the Al₂O₃ surface was decreased by adding Fe₂O₃. Analysis of the used catalysts suggested that the addition of Fe₂O₃ inhibited sintering of supported Pt particles. The addition of Sn to Pt/Fe₂O₃-Al₂O₃ further improved the dehydrogenation activity of the catalyst. This catalyst showed better catalytic activity than that of Pt-Sn/Zn-Al-O, which has been employed in a commercial process and has been reported as an excellent catalyst in dehydrogenation reactions. We claim that we have developed a novel dehydrogenation catalyst system, Pt-Sn/Fe₂O₃-Al₂O₃, which has better catalytic properties than the reported commercial catalyst.

Keywords: Iron oxide addition; Isobutane dehydrogenation; Pt-Sn catalyst; CO adsorption; Catalyst deactivation

Reductive amination of 2-propanol to monoisopropylamine over Co/γ-Al₂O₃ catalysts by Jun Hee Cho; Jung Hyun Park; Tae-Sun Chang; Gon Seo; Chae-Ho Shin (pp. 313-319).

Display Omitted► Reductive amination of 2-propanol over Co/γ-Al₂O₃ catalysts. ► High yield in monoisopropylamine is controlled by the reaction parameters. ► The conversion of 2-propanol was correlated to the surface area of cobalt metal. ► Excess hydrogen could efficiently hinder the phase transition of catalyst.Co/γ-Al₂O₃ catalysts with 4–27wt% cobalt loadings were prepared by incipient-wetness impregnation and used to catalyze the synthesis of monoisopropylamine by the reductive amination of 2-propanol in the presence of hydrogen and ammonia. The catalysts were characterized by X-ray diffraction, H₂-temperature programmed reduction, N₂-sorption, and H₂-chemisorption. 23wt% Co loading resulted in the highest catalytic activity and a long-term stability of up to 100h on stream. 2-Propanol conversion was related to the exposed metal surface area and the number of exposed cobalt atoms. In the absence of hydrogen, the catalyst was progressively deactivated; its initial activity and selectivity were completely recovered upon re-exposure to hydrogen. The deactivation was due to the formation of metal nitride caused by the strong adsorption of ammonia on the surface of the metal phase. Excess hydrogen hindered the phase transition to metal nitride, preventing deactivation.

Keywords: 2-Propanol; Acetone; Reductive amination; Cobalt; Monoisopropylamine

Sections

Personal tools

Applied Catalysis A, General (v.417-418, #)

Sections

Personal tools

Local resources

Applied Catalysis A, General (v.417-418, #)