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Applied Catalysis A, General (v.456, #)
New catalytic reactors prepared from symmetric and asymmetric ceramic hollow fibres by F.R. García-García; K. Li (pp. 1-10).
Display Omitted► Two new catalytic hollow fibre based reactors are developed: SHFR and AHFR. ► Dimension of finger-like and sponge-like regions determine the catalyst particle size. ► AHFR and SHFR performance was compared with that in a FBR during the WGS reaction. ► AHFR and SHFR design improves the mass transfer allowing an enhanced H2 production.In this study, asymmetric and symmetric Al2O3 hollow fibres were employed as a support of a 10% CuO/CeO2 catalyst in the development of an asymmetric hollow fibre reactor (AHFR) and a symmetric hollow fibre reactor (SHFR), respectively. The 10% CuO/CeO2 catalyst was successfully deposited in both Al2O3 hollow fibre substrates by the sol–gel Pechini method. The impregnated fibres were characterized by Ar permeability, Hg porosimetry, X-ray diffraction, scanning electron microscopy (SEM), transmission electron microscopy (TEM) and high-resolution optical microscopy. The water gas shift (WGS) reaction was chosen as a sample reaction to compare the performances of both AHFR and SHFR with a traditional fixed bed reactor (FBR). The catalytic activity tests in the FBR were carried out using the powder ground from either the asymmetric or symmetric Al2O3 hollow fibre impregnated with 10% CuO/CeO2. Two different configurations, “dead-end” and “open-end”, were studied in the AHFR and SHFR. The experimental results show that, despite the differences observed between the AHFR and SHFR, both reactors offer important advantages over conventional FBRs including high catalytic activity along with a better selectivity.
Keywords: Al; 2; O; 3; hollow fibres; Asymmetric; Symmetric; Catalyst; Flow-through operation
Toward bifunctional catalysts for the direct conversion of syngas to gasoline range hydrocarbons: H-ZSM-5 coated Co versus H-ZSM-5 supported Co by Sina Sartipi; Johannes E. van Dijk; Jorge Gascon; Freek Kapteijn (pp. 11-22).
Display Omitted► One-step production of gasoline range hydrocarbons from syngas using bi-functional catalysts. ► Combination of zeolites and Co nanoparticles breaks ASF distribution. ► Close vicinity of zeolitic acid sites and Co is crucial. ► Co supported on mesoporous H-ZSM-5 more effective than Co coated with ZSM-5 catalysts.One step production of gasoline range hydrocarbons from syngas is demonstrated by combination of Fischer–Tropsch synthesis (FTS) and acid functionalities in one single bifunctional catalyst particle. Two different catalyst configurations were studied in which the acid functionality of H-ZSM-5 zeolite conjoins the cobalt FTS active phase: (i) H-ZSM-5 as catalytic coating on Co and (ii) H-ZSM-5 as catalytic support for Co. Spherical shaped Co/SiO2 was chosen as a conventional FTS catalyst for comparison and used as precursor to synthesize the H-ZSM-5 coated Co catalyst. Various Silicalite-1 and H-ZSM-5 coated reference samples were prepared by subjecting Co/SiO2 to a direct hydrothermal procedure. Thorough characterization and catalytic performance tests reveal that direct hydrothermal synthesis results in transformation of SiO2 from the Co/SiO2 particles into an MFI coating of Co agglomerates. The silica support does not only act as precursor but also as nano-mold during the preparation of the zeolite coated catalysts as the original Co/SiO2 particle shape is preserved. The close vicinity of the acid sites and Co function in the zeolite coated catalysts promotes the acid catalyzed conversion of the produced FTS hydrocarbons and reduces the production of C12+. Alternatively, mesostructured H-ZSM-5 was used to support Co. Mesoporous hierarchy in the latter case improves both the Co dispersion and the proximity of FTS and acid sites. Thus, Co supported on mesoporous H-ZSM-5 is a much more effective catalyst for the direct production of gasoline range hydrocarbons than the H-ZSM-5 coated Co catalyst.
Keywords: Fischer–Tropsch; Bifunctional catalyst; H-ZSM-5; Cobalt; Mesoporous zeolite; Coating; Selectivity control
Al-containing mesoporous carbon as effective catalysts for the chemoselective reduction of carbon–carbon double bonds in nitrostilbene derivatives by Liuchang Wang; Yanjun Zheng; Xiquan Zhang; Hongmei Gu; Jiang Li; Wei Wang; Baolin Li (pp. 23-29).
Display Omitted► An efficient method for high chemoselectively reduce the CC bond was established. ► The reaction conditions are relatively mild, low cost and environmentally benign. ► Al–MCs as efficient catalysts were prepared by multi-component co-assembly strategy. ► The selective reduction nitro group was also achieved under corresponding condition.A series of Al, Mn, Cu and Fe metal-containing mesoporous carbon catalysts were synthesized for catalyzing selective reduction of carbon–carbon double bond in 4-nitrostilbene analogs bearing nitro group with hydrazine hydrate. The results indicated that the reduction reaction was able to be achieved successfully between carbon–carbon double bond and nitro group. The efficient method has been developed for the reduction of CC double bonds with diimide, catalytically generated in situ from hydrazine hydrate by the synthesized catalysts. The 0.15Al–MC1 as heterogeneous catalyst exhibited the highest catalysis activity and chemoselectivity in all synthesized catalysts. In the presence of 0.15Al–MC1, the reduction of carbon–carbon double bond in 4-nitrostilbene derivatives was up to 99% yield and >99% chemoselectivity at 70°C in ethanol. On the other hand, the high selective reduction of nitro group in 4-nitrostilbenes was also facile to be achieved with hydrazine hydrate, active carbon and FeCl3·6H2O under inert atmosphere.
Keywords: Al-containing mesoporous carbon; Selective reduction; Carbon–carbon double bond; Hydrazine; Heterogeneous catalysis
Fractal analysis of catalyst surface morphologies on hydrogenation in process of 2-((1-benzylpiperidin-4-yl)methyl)-5,6-dimethoxy-2,3-dihydroinden-1-one hydrochloride synthesis by Želimir Jelčić; Zrinka Mastelić Samardžić; Stanka Zrnčević (pp. 30-43).
Display Omitted► The fractal dimensions for the Pt/C catalysts effect the reaction kinetic terms. ► The catalyst “interface” fractal indices are related to the Weibull equation terms. ► The catalyst “interface” fractal indices effect the impurity rate constants.Catalytic hydrogenation of 2-((1-benzyl-1,2,3,6-tetrahydropyridin-4-yl)methylene)-5,6-dimethoxy-2,3-dihydroinden-1-one hydrochloride (1) to 2-((1-benzylpiperidin-4-yl)methyl)-5,6-dimethoxy-2,3-dihydroinden-1-one hydrochloride (2) was investigated in batch-slurry reactor. The 5% Pt/C catalysts were chosen for optimizing the catalytic activity. The catalyst activity has been changed by using the differently morphologically structured fractal catalysts. The kinetic terms of hydrogenation for (1) change with the fractal dimensions of the 5% Pt/C catalyst. The most active and selective (with the highest reaction rate for production of (2), and with the least impurities level) is the catalyst K3, and the worst the catalyst K4. This most active and selective catalyst has an intermediate fractal surface dimension, D F,ads=2.77, and the worst catalyst is represented by almost smooth surface with a high D F,ads=2.82. The interface D[ BW] fractal indices (derived from the thresholded SEM images, at the magnifications in the range 600–2000×) are largest ones for the most suitable catalyst K3, and lowest for the catalyst K4.
Keywords: Catalyst; Hydrogenation; Fractal; Reaction kinetic
Cu catalyzed oxidation of 5-hydroxymethylfurfural to 2,5-diformylfuran and 2,5-furandicarboxylic acid under benign reaction conditions by Thomas S. Hansen; Irantzu Sádaba; Eduardo J. García-Suárez; Anders Riisager (pp. 44-50).
Display Omitted► Aerobic oxidation of HMF to DFF was performed at ambient conditions with CuCl/TEMPO. ► An optimized DFF yield of 95% was obtained with use of nitrogen containing promoters. ► HMF was oxidized directly to FDA by oxidation with CuCl/ t-BuOOH catalyst.The renewable chemical building block 5-hydroxymethylfurfural (HMF) was oxidized to 2,5-diformylfuran by an oxidation system consisting of the radical 2,2,6,6-tetramethyl-piperidin-1-oxyl (TEMPO) and CuCl. The system was optimized by exploring several reaction conditions and by employing nitrogen containing promoters (NCPs) to obtain excellent yields. In acetonitrile a 95% DFF yield was obtained after 24h with ambient pressure of dioxygen at room temperature in the presence of different NCPs, which – to our knowledge – is the best result reported thus far for this reaction. The use of NCPs made it further possible to apply various traditional solvents, e.g. acetone, methanol and methyl isobutyl ketone for the reaction. The latter can be used as extraction solvent for HMF synthesis in aqueous media and thus integrate the two processes. Additionally, HMF was oxidized to 2,5-furandicarboxylic acid by a modified oxidation protocol consisting of CuCl and t-BuOOH. In all the reactions, mild conditions, including room temperature were employed.
Keywords: 5-Hydroxymethylfurfural; Oxidation; Copper; Radical reactions; 2,5-Diformylfuran
Studies on calcined cow bone and pyrolyzed wood, suitable supports for immobilizing hybrid nano particles of Co-Mn as new catalysts for oxidation of 2,6-diisopropyl naphthalene by Atefeh Mardani Ghahfarrokhi; Parisa Moshiri; Mehran Ghiaci (pp. 51-58).
Display Omitted► Two new catalysts have been prepared by immobilizing Co/Mn nano-hybrid particles on calcined cow bone, and pyrolyzed wood. ► Co/Mn containing catalysts have been tested in the oxidation of 2,6-diisopropylnaphthalene under diverse conditions. ► This work is the first detailed report of the effect of bone and wood as convenient supports for the Co/Mn catalyst.Catalytic oxidation of 2,6-diisopropylnaphthalene (2,6-DIPN) to 2,6-naphthalene dicarboxylic acid (2,6-NDCA) was studied with two new catalysts prepared by immobilization of Co/Mn nano-hybrid particles over calcined cow bone, and pyrolyzed wood. The catalysts have the advantage of very cheap supports, and easy catalyst recovery. The effects of Co/Mn atomic ratio, reaction time and temperature, oxygen pressure, amount of catalyst, and the support on the conversion of 2,6-DIPN and product/intermediate yields were investigated. There was an interesting synergistic effect of cobalt and manganese catalysts. The maximum product (2,6-NDCA) yield was 100%, obtained at a Co/Mn atomic ratio of 10 supported on pyrolyzed wood. Lower cobalt concentration resulted the lower 2,6-NDCA yield, which was ascribed to the intermediate products formation. The catalysts were characterized in detail by SEM/EDS, BET surface area, and TEM measurements. Transmission electron microscopy (TEM) measurements indicated nanoparticles (diameter of about 2–5nm) on the surface of the supports.
Keywords: Hybrid nanoparticles; Catalyst; Oxidation; Cow bone; Pyrolyzed wood; 2,6-Diisopropylnaphthalene
Catalytic decomposition of 1,3-diphenoxybenzene to monomeric cyclic compounds over palladium catalysts supported on acidic activated carbon aerogels by Hai Woong Park; Jeong Kwon Kim; Ung Gi Hong; Yoon Jae Lee; Jung Ho Choi; Yongju Bang; In Kyu Song (pp. 59-66).
Display Omitted► Pd catalysts supported on acidic ACAs (activated carbon aerogels) were prepared. ► Catalytic decomposition of 1,3-diphenoxybenzene was conducted. ► Acidity of the catalysts played an important role in the reaction. ► Total yield for monomeric cyclic compounds increased with increasing catalyst acidity.Activated carbon aerogel (ACA) was prepared by a chemical activation of carbon aerogel using phosphoric acid (H3PO4). Activated carbon aerogel bearing sulfonic acid (ACA-SO3H), Cs2.5H0.5PW12O40-impregnated activated carbon aerogel (Cs2.5H0.5PW12O40/ACA), and Cs2.5H0.5PW12O40-impregnated activated carbon aerogel bearing sulfonic acid (Cs2.5H0.5PW12O40/ACA-SO3H) were prepared in order to provide acid sites to ACA. Palladium catalysts were then supported on ACA, ACA-SO3H, Cs2.5H0.5PW12O40/ACA, and Cs2.5H0.5PW12O40/ACA-SO3H by an incipient wetness impregnation method. The prepared Pd/ACA, Pd/ACA-SO3H, Pd/Cs2.5H0.5PW12O40/ACA, and Pd/Cs2.5H0.5PW12O40/ACA-SO3H catalysts were applied to the decomposition of 1,3-diphenoxybenzene. 1,3-Diphenoxybenzene was used as a trimeric lignin model compound for representing C-O bond in lignin. Cyclohexanol, benzene, and phenol were mainly produced by the decomposition of 1,3-diphenoxybenzene. 4-Phenoxyphenol was also produced as an intermediate by the decomposition of 1,3-diphenoxybenzene. Conversion of 1,3-diphenoxybenzene and total yield for main products (cyclohexanol, benzene, and phenol) increased with increasing acidity of the catalysts. Among the catalysts tested, Pd/Cs2.5H0.5PW12O40/ACA-SO3H with the largest acidity showed the highest conversion of 1,3-diphenoxybenzene and total yield for main products. Pd/Cs2.5H0.5PW12O40/ACA-SO3H also served as a stable and reusable catalyst in the decomposition of 1,3-diphenoxybenzene.
Keywords: Acidic activated carbon aerogel; Heteropolyacid; Pd catalyst; Lignin decomposition; 1,3-Diphenoxybenzene
Catalytic oxidation-extractive desulfurization for model oil using inorganic oxysalts as oxidant and Lewis acid-organic acid mixture as catalyst and extractant by Hongyan Song; Jiajun Gao; Xingyu Chen; Jing He; Chunxi Li (pp. 67-74).
Display Omitted► BT and DBT in model oil are removed easily via a catalytic oxidation-extractive process. ► KMnO4 or K2Cr2O6 is an efficient oxidant for the sulfur in some Lewis organic acid mixtures. ► The catalysis of the oxidant can be effectively adjusted by the type and amount of Lewis acid. ► The acetic acid-Lewis acid mixtures are effective extractants for the oxidized sulfurs.The catalytic oxidation-extractive desulfurization (COEDS) performance for benzothiophene (BT-) and dibenzothiophene (DBT-) containing oils is studied at room temperature with respect to three inorganic oxysalt oxidants (KMnO4, K2Cr2O7, and NaClO4) under the catalysis of an acid mixture being composed of different kinds and amounts of Lewis acid (FeCl3, ZnCl2 or CuCl2) and organic acid (formic, acetic or propionic acid). The results show that both KMnO4 and K2Cr2O7 are efficient oxidants, and their oxidizability can be adjusted effectively by the types and tuned slightly by the amounts of the Lewis acid used, and acetic acid is an appropriate organic acid. DBT is oxidized only to DBTO2, while BT is converted to two to over six oxidized S-species depending on the Lewis acid used. 1-hexene presented in oil can slightly lower the S-conversion, but a promising desulfurization rate of over 92% for both BT and DBT can be also achieved under appropriate conditions.
Keywords: Catalytic oxidation extractive desulfurization; Benzothiophene; Dibenzothiophene; Model oil; Lewis acid
Preparation and performance of Co based capsule catalyst with the zeolite shell sputtered by Pd for direct isoparaffin synthesis from syngas by Yuzhou Jin; Ruiqin Yang; Yasuhiro Mori; Jian Sun; Akira Taguchi; Yoshiharu Yoneyama; Takayuki Abe; Noritatsu Tsubaki (pp. 75-81).
Display Omitted► Using sputtering method to modify zeolite shell of Co/SiO2-Z by metallic Pd. ► One catalyst integrating all catalytic functions of three kinds of catalyst (Co/SiO2, HZSM-5, Pd). ► Realizing simple one-step isoparaffin synthesis via Fischer–Tropsch process. ► Increasing isoparaffin selectivity on catalyst Co/SiO2-Z-Sp-Pd compared with Co/SiO2-Z-IW-Pd.The mm-sized capsule catalyst Co/SiO2-Z with the H-type zeolite (HZSM-5) as the shell, and the Co/SiO2-Z-Sp-Pd capsule catalyst with Pd loaded by sputtering method, as well as the Co/SiO2-Z-IW-Pd capsule catalyst, loading the Pd by incipient wetness impregnation, were prepared and used for isoparaffin direct synthesis by Fischer–Tropsch synthesis reaction from syngas with H2/CO ratio of 2/1 at 1.0MPa and 533K. The analysis results of XRD, SEM, EDS and NH3-TPD showed that a compact HZSM-5 shell was formed on the Co/SiO2 pellet, and the metallic Pd was well sputtered on the surface of the HZSM-5 shell for the Co/SiO2-Z-Sp-Pd catalyst. The isoparaffin and olefin selectivity increased in the FTS reactions on the HZSM-5 capsule catalyst than on the Co/SiO2 catalyst. The selectivity of isoparaffins increased, and the selectivity of olefins decreased when using the Co/SiO2-Z-Sp-Pd catalyst, compared with the Co/SiO2-Z catalyst or the Co/SiO2-Z-IW-Pd catalyst, because metallic Pd introduced by sputtering on the zeolite shell could hydrogenate olefins efficiently. It was suitable to use the sputtering method for the preparation of the zeolite capsule catalyst loaded with metallic Pd, as conventional impregnation method could not reduce Pd cation due to the strong interaction from zeolite surface. The CO conversion, CH4 and CO2 selectivity on the catalyst of Co/SiO2-Z-Sp-Pd increased with temperature increasing from 513K to 553K. At elevated temperature, the isoparaffin selectivity also increased while the olefin selectivity was suppressed.
Keywords: Capsule catalyst; HZSM-5; Palladium (Pd); Sputtering; Fischer–Tropsch synthesis (FTS)
Direct conversion of ethane to acetic acid over H-ZSM-5 using H2O2 in aqueous phase by Abul Kalam Md. Lutfor Rahman; Rie Indo; Hidehisa Hagiwara; Tatsumi Ishihara (pp. 82-87).
Display Omitted► Effective production of acetic acid of 19% and formic acid of 14% (based on ethane) was achieved. ► Protonated pentasil-type zeolite (H-ZSM-5) was used as an active solid acid catalyst. ► The acid site of the catalyst seems to be the active site for partial oxidation. ► Triphenylphosphine is useful additive for improving yield.Partial oxidation of ethane on protonated pentasil-type zeolite (H-ZSM-5) was studied by using hydrogen peroxide (H2O2), an environment friendly oxidizing agent. Acetic acid (CH3COOH) and formic acid (HCOOH) were obtained with high yield and selectivity from ethane. In addition, the influence of reaction parameters such as temperature, pressure, amount of oxidizing agent, and reaction period was investigated. Yields of acetic acid and formic acid (based on ethane) were achieved up to values of 18.7% and 14%, respectively, under the optimized reaction condition of 393K and 3.0MPa. Selectivity to both compounds is 84% under this condition. The amount of oxidant (H2O2) was optimized to be 279mmol for the reaction. A low silica to alumina ratio in H-ZSM-5 was favorable for the partial oxidation of ethane. CO2 formation was observed as a deep oxidation product at initial period. Partial oxidation was observed to occur within a short reaction period and was associated with the active oxygen species produced from H2O2 and CO2 formed through the deep oxidation of ethane. Since the yield of CH3COOH from ethane is much higher than that from ethylene, partial oxidation on H-ZSM-5 proceeds through a reaction mechanism different from that of a Wacker-type oxidation reaction.
Keywords: Acetic acid; Liquid phase oxidation; Ethane; H-ZSM-5
Synthesis and application of gold-carbon hybrids as catalysts for the hydroamination of alkynes by Andrés Seral-Ascaso; Asunción Luquin; María Jesús Lázaro; Germán F. de la Fuente; Mariano Laguna; Edgar Muñoz (pp. 88-95).
Display Omitted► Gold-carbon hybrids were used as catalysts for the hydroamination of phenylacetylene with aniline. ► Conversion values of up to 79% were achieved with these gold-carbon catalysts. ► A variety of carbon materials was efficiently used as supports for these catalysts. ► High conversion values can be achieved adjusting the gold:carbon support w/w ratios. ► Graphene oxide, nanotubes, carbon black, and nanodiamond led to the highest conversion values.Gold-carbon hybrids have been efficiently used as catalysts for the hydroamination of phenylacetylene with aniline. Carbon supports (single-walled and multi-walled carbon nanotubes, graphene oxide, graphite, graphitic cones, nanodiamond, ordered mesoporous carbon, carbon xerogel, carbon black, activated carbon, and laser-ablation produced carbon foam) were homogenously decorated with gold nanoparticles (GNP) synthesized by in situ reduction of chloroauric acid (H[AuCl4]) in water. The performance of carbon materials used as catalytic supports has been here evaluated. The synthesized gold-carbon hybrids worked remarkably well as catalysts for the targeted reaction. Conversion values as high as 79% were achieved by suitably adjusting the gold:carbon support w/w ratios. Our results indicate that the catalytic activity strongly depends on gold:carbon support w/w ratios and on the structure and textural properties and dispersibility of the carbon supports used. Thus, the best gold-carbon catalyst performance in terms of conversion values and low carbon support content has been achieved when using graphene oxide as well as supports (carbon black, carbon nanotubes, and nanodiamond) that combine high BET surface areas, well-developed mesoporosity, and good dispersibility in water during the GNP decoration process.
Keywords: Gold-carbon catalysts; Gold nanoparticles; Hydroamination; Carbon supports; Gold-carbon hybrids
Influence of the synthesis route on the catalytic oxidation of 1,2-dichloroethane over CeO2/H-ZSM5 catalysts by B. de Rivas; C. Sampedro; E.V. Ramos-Fernández; R. López-Fonseca; J. Gascon; M. Makkee; J.I. Gutiérrez-Ortiz (pp. 96-104).
.Display Omitted► Ceria deposition promoted the activity of H-ZSM5 zeolite. ► Reaction temperatures for Cl-VOC oxidation were lowered by 60°C. ► Impregnation of ceria with ethanol resulted an efficient synthesis route. ► Activity was governed by a relatively reduced crystallite size. ► A more effective oxygen mobility was achieved.The performance of supported CeO2/HZSM-5 catalysts with a nominal CeO2 loading of 10wt.% was evaluated for the oxidation of one of the most common chlorinated pollutants found in waste streams, namely 1,2-dichloroethane. The influence of the preparation method, such as impregnation in different media (water and ethanol), precipitation and ion exchange, was examined. Structural, morphological and physico-chemical changes caused as a function of the synthesis procedure were analysed by atomic emission spectroscopy, X-ray diffraction, BET measurements, transmission electronic microscopy, X-ray photoelectron spectroscopy, NH3-temperature-programmed desorption, adsorption of CO at low temperature followed by infrared spectroscopy, temperature-programmed reduction with hydrogen, energy dispersive X-ray spectroscopy and dynamic thermogravimetry coupled to mass spectrometry. The enhancement of the catalytic behaviour of the resulting ceria loaded samples with respect to plain H-ZSM5 could be explained on the basis of the synergetic effects of oxygen mobility and acid sites. In particular, the procedure based on impregnation with ethanol led to a highly dispersed ceria catalyst with a larger amount of oxygen vacancies. As a result, this catalyst required a temperature lower than 200°C for attaining 50% conversion.
Keywords: Cl-VOCs; Catalytic oxidation; 1,2-dichloroethane; Supported cerium oxide; H-ZSM-5 zeolite; Synthesis procedure
Activation of n-octane using vanadium oxide supported on alkaline earth hydroxyapatites by Venkata D.B.C. Dasireddy; Sooboo Singh; Holger B. Friedrich (pp. 105-117).
Display Omitted► Oxidation of n-octane using vanadium oxide supported on hydroxyapatites. ► V2O5 loadings of 2.5wt% and 10wt% was supported on hydroxyapatites. ► Vanadium oxide supported on Sr-HAp showed best activity. ► The selectivity towards the products depends upon the oxidative environment strength. ► The cyclization mode is related to the dominant octene isomer formed.Vanadium pentoxide was supported on calcium, strontium, magnesium and barium hydroxyapatite with loadings of 2.5 and 10wt% by the wet impregnation technique. The materials were characterized by XRD, ICP-OES, BET, FTIR, SEM, TEM, TPR and TPD. From XRD and IR analyses, vanadium is found in the vanadium pentoxide phase for the 2.5wt% loadings, whereas an additional pyrovanadate phase exists for the 10wt% loadings. Electron microscopy provides evidence of a homogenous distribution of the vanadium species on the hydroxyapatite. Oxidative dehydrogenation reactions carried out in a continuous flow fixed bed reactor showed that selectivity towards desired products was dependent on the phase composition of the catalyst and the n-octane to oxygen molar ratios. For the n-octane to oxygen molar ratio of 1:0.5, selectivity towards aromatics and octenes was obtained, whereas the n-octane to oxygen molar ratio of 1:2 showed selectivity towards aromatics and oxygenates. Good selectivity towards octenes was achieved using the 2.5wt% V2O5 loaded hydroxyapatite catalysts. There was a marked decrease in octene selectivity and a significant increase in the formation of C8 aromatics when the 10wt% loaded catalyst was used. In general, for the activation of n-octane, 3-octene in the octenes, o-xylene in the aromatics and 2-octanone in the oxygenates were the major products. At iso-conversion of 27% at 450°C, V2O5 supported Ca-HAp showed highest selectivity towards octenes, V2O5 supported Sr-HAp showed highest selectivity towards aromatics, V2O5 supported Mg-HAp showed highest selectivity towards oxygenates and V2O5 supported Ba-HAp showed selectivity towards aromatics and oxygenates.
Keywords: Hydroxyapatite; V; 2; O; 5; n; -Octane; Octenes; o; -xylene; Oxidative dehydrogenation
Recyclable, highly efficient and low cost nano-MgO for amide synthesis under SFRC: A convenient and greener ‘NOSE’ approach by Vijay Kumar Das; Rashmi Rekha Devi; Ashim Jyoti Thakur (pp. 118-125).
Display Omitted► A clean synthesis of amide derivatives has successfully been accomplished. ► Nano-MgO was found to be highly active. ► Reusable nano-MgO under ‘SFRC’ has been used in a ‘NOSE’ approach. ► Measurement of “green-ness” by using green metrics. ► The ‘green-ness’ of this protocol makes it a benign alternative method.A clean synthesis of amide derivatives has successfully been accomplished utilizing reusable nano-MgO under ‘SFRC’ (solvent free reaction condition). The ‘green-ness’ of this protocol makes it a benign alternative for the large scale synthesis.
Keywords: Nano-MgO; NOSE; SFRC; Amide; Green-ness
Magnetic amphiphilic nanocomposites produced via chemical vapor deposition of CH4 on Fe–Mo/nano-Al2O3 by Aline A.S. Oliveira; Ivo F. Teixeira; Leandro P. Ribeiro; Eudes Lorençon; José D. Ardisson; Luis Fernandez-Outon; Waldemar A.A. Macedo; Flávia C.C. Moura (pp. 126-134).
•Production of amphiphilic composites via catalytic CVD with nano-alumina and CH4.•Use of Fe and Mo catalysts for the growth of carbon nanostructures during CVD.•Combination of a hydrophilic matrix with a partial hydrophobic carbon coating.•Composites act as emulsifiers and demulsifiers due to be amphiphilic and magnetic.•Composites catalyze biphasic reactions, especially oxidation of organics with H2O2.Catalytic chemical vapor deposition (CVD) using methane as carbon source was used to produce amphiphilic magnetic nanocomposites from Fe and Mo catalysts supported on alumina nanoparticles. The materials were reduced by hydrogen up to 900°C and after were partially coated by carbon during a CVD process with CH4 also up to 900°C. TPR results showed that the Fe and Mo phases present in the composites were reduced mainly to Fe0, Mo0 and iron carbide that consequently confers interesting magnetic properties to the materials. The materials produced with different Fe/Mo contents show saturation of magnetization between 1.1 and 28.1emug−1. Thermal analyses, CHN, Raman spectroscopy, SEM, TEM, EDS and BET showed that the higher the metal content, the more carbon was deposited on the materials. Carbon content of the materials varies from 2 to 16% and it is distributed mainly as nanotubes and nanofibers. These composites present excellent interaction on the interface between oil and water and are able to form emulsions as well as to break other stable emulsions. This feature is strategic to these composites as catalysts to act on the interface of biphasic systems. Preliminary studies of the materials as catalysts on biphasic oxidation of lipophilic dye Sudan-IV showed very promising results.
Keywords: Amphiphilic; Magnetic; Emulsions; Biphasic reactions
Catalytic activity of Au-Cu/CeO2-ZrO2 catalysts in steam reforming of methanol by Chinchanop Pojanavaraphan; Apanee Luengnaruemitchai; Erdogan Gulari (pp. 135-143).
Display Omitted► The Au-Cu/CeO2-ZrO2 catalysts showed superior SRM activity. ► The highly dispersed CuO x led to an active alloy phase. ► The Au–Cu alloy exhibited superior stability with less influence on coke formation.Bimetallic Au-Cu/Ce0.75Zr0.25O2 catalysts prepared by deposition–precipitation were tested for steam reforming of methanol (SRM) in the range of 200–500°C. Many effective parameters—Au/Cu atomic ratio, gas pretreatment, total metal loading, and calcination temperature—were investigated and correlated with catalyst properties. At the Au/Cu ratio of 1/3, the homogeneous Au–Cu alloy was found to be active for SRM, while an inhomogeneous or partially developed alloy formation was found after applying H2 and O2 pretreatments. There were no significant differences in catalytic activity with different total loadings and calcination temperatures; however, the 7wt% Au-Cu catalyst calcined at 300°C exhibited complete methanol conversion, 82% H2 selectivity, and 1% CO selectivity at a low temperature of 300°C. In regards to stability, the bimetallic catalyst displayed a long life, even though coke and metallic copper were formed.
Keywords: Steam reforming of methanol; Hydrogen; Alloy; Bimetallic; Au catalyst
Electrochemical strategy for grown ZnO nanoparticles deposited onto HY zeolite with enhanced photodecolorization of methylene blue: Effect of the formation of SiOZn bonds by N. Sapawe; A.A. Jalil; S. Triwahyono; R.N.R.A. Sah; N.W.C. Jusoh; N.H.H. Hairom; J. Efendi (pp. 144-158).
Display Omitted► Electrochemical method generates the growth of ZnO less than 30nm in size. ► Isomorphous substitution of Al with Zn occurred during the electrolysis. ► A new structural model for EGZnO/HY is proposed. ► SiOZn bonds were formed as proven by MAS NMR, XPS, and IR. ► 1wt% EGZnO/HY exhibited the best performance for the photodecolorization of MB.Nanoparticles of electrogenerated zinc-supported HY zeolite (EGZnO/HY) catalyst were prepared by a simple electrochemical method. The interaction between zinc species and HY support during the electrolysis was found to affect the EGZnO/HY structure. In addition to the formation of EGZnO nanoparticles (<30nm in size) that distributed on the surface of HY support, an isomorphous substitution of Al with Zn also occurred in the aluminosilicate framework to result in a SiOZn bonds. The photoactivity of EGZnO/HY was tested on the decolorization of methylene blue (MB). An amount of 0.375gL−1 of 1wt% EGZnO/HY was found to be the optimum dosage for 10mgL−1 MB, which resulted in 80% of maximum decolorization after 6h of contact time at pH 3 under fluorescent light (420nm). Increasing the EGZnO loading led to additional formation of SiOZn bonds and lessened the number of EGZnO nanoparticles, which then reduced the photodecolorization percentage of MB.The photocatalytic reaction was follows the first-order Langmuir–Hinshelwood model, and gives partially mineralization. The photocatalyst was still stable after five cycling runs with no Zn leaching.
Keywords: EGZnO/HY; Electrochemical; Isomorphous substitution; Photodecolorization; Methylene blue
High-temperature reaction of SiO2 with methanol: Nucleophilic assistance of some N-unsubstituted benzazoles by Andrey M. Chibiryaev; Ivan V. Kozhevnikov; Oleg N. Martyanov (pp. 159-167).
•Different forms of SiO2 react slowly with methanol at 350°C to give mainly TMOS.•Some N-unsubstituted benzazoles increase considerably the amount of reacted SiO2.•The key role of heterocycles is nucleophilic assistance to the reaction.•Azole ring of heterocycles is methylated by MeOH during the reaction.•Both SiO2-surface and TMOS catalyze the methylation of benzazole.SiO2-containing materials (quartz, Pyrex glass, silica gel, and H-Y zeolite) react slowly with methanol at 350°C under both supercritical and gas-phase conditions. The amount of SiO2 reacted with supercritical methanol depends on the kind of the material and is varied from 0.05wt% for quartz sand to 4.0wt% for wide-porous silica gel for 5h of the reaction. The main products of the reaction are methyl orthosilicates, mainly tetramethyl orthosilicate. N-Unsubstituted 1 H-indole, 1 H-benzimidazole, and 1 H-indazole additives considerably increase the amount of reacted SiO2-containing material. Noteworthy, quartz sand “solubility” is increased ca 14-fold when indole is used at the same reaction conditions. These benzazoles provide a nucleophilic assistance to the reaction between SiO2 and methanol. During the assistance, the azole ring is methylated by methanol, and the participation of SiO2-surface or tetramethyl orthosilicate molecule facilitates the alkylation reaction of benzazole used.
Keywords: SiO; 2; -containing materials; Supercritical methanol; Tetramethyl orthosilicate; Benzazole methylation catalyst; Nucleophilic assistance
Kinetic investigation of sorbitol and xylitol dehydration catalyzed by silicotungstic acid in water by Jens Uwe Oltmanns; Stefan Palkovits; Regina Palkovits (pp. 168-173).
Display Omitted► Kinetic behavior of sorbitol and xylitol dehydration was investigated. ► Differential equations for modeling sorbitol and xylitol dehydration were proposed. ► Reaction rates at different temperatures could be obtained. ► Activation energies for all reaction steps were successfully calculated. ► Selectivity of sorbitol dehydration could be influenced by temperature.Sorbitol and xylitol dehydration reactions have been investigated regarding their kinetic properties. The reactions were catalyzed by silicotungstic acid in water under hydrogen pressure at temperatures ranging from 160°C to 200°C. The products have been measured by HPLC at regular intervals and reaction models have been developed based on these results. Modeling of the experimental data has been done with Presto-Kinetics® and the resulting reaction rates have been used to determine activation energies of all involved reaction steps. By this way, a set of four activation energies was obtained for the dehydration of sorbitol to its products, including 1,4-sorbitan and isosorbide. The activation energy for the dehydration of xylitol to 1,4-anhydroxylitol could also be obtained.
Keywords: Sorbitol; Xylitol; Dehydration; Kinetic investigation; Activation energy
Pyrolyzer–GC/MS system-based analysis of the effects of zeolite catalysts on the fast pyrolysis of Jatropha husk by Takehisa Mochizuki; Shih-Yuan Chen; Makoto Toba; Yuji Yoshimura (pp. 174-181).
Display Omitted► Fast pyrolysis of Jatropha residues and cedar were preformed over several zeolites. ► The products of the pyrolysis processes were analyzed using pyrolyzer–GC/MS. ► Jatropha exhibited specific reactivity during the catalytic fast pyrolysis process. ► Coke and PAHs were produced in small amounts in the presence of H-Beta zeolite.Samples of Jatropha husk and cedar wood were catalytically pyrolyzed at 500°C using the zeolites H-USY, H-Mordenite, H-Beta, and H-ZSM-5 as catalysts. The products of the pyrolysis processes were analyzed using a pyrolysis–gas chromatography/mass spectrometry (Py–GC/MS) system. The fast pyrolysis of the Jatropha husk sample in the presence of the zeolites produced aromatic hydrocarbons in greater amounts than those produced during the pyrolysis of the cedar sample. Jatropha husk exhibited specific reactivity during the catalytic fast pyrolysis process. Among the catalysts evaluated, the zeolite H-USY exhibited the highest activity as evidenced by the changes in the pyrolysis products. It also exhibited the highest selectivity with respect to monocyclic aromatic hydrocarbons (MAHs). However, the use of this catalyst also resulted in an increase in the formation of the solid residue remaining after the pyrolysis process, which comprised coke and polycyclic aromatic hydrocarbons (PAHs) such as naphthalene and phenanthrene. In contrast, coke and PAHs were produced in very small amounts when the zeolite H-Beta was used. Furthermore, its selectivity with respect to MAHs was lower than those of the zeolites H-USY and H-ZSM-5 when used in the Jatropha husk/zeolite weight ratio of 1:1. When catalytic fast pyrolysis was carried out at a Jatropha husk/zeolite weight ratio of 1:5, selectivity with respect to the MAHs increased drastically. However, there was no concomitant increase in the production of coke and PAHs. The fact that coke and PAHs were produced in smaller amounts during the fast pyrolysis of Jatropha husk when the zeolite H-Beta was used as the catalyst makes it attractive for increasing the yield of MAHs during the pyrolysis of biomasses.
Keywords: Catalytic fast pyrolysis; Jatropha; Zeolite catalyst; Pyrolyzer–GC/MS; Bio-oil
Production of biodiesel from mixed waste vegetable oils using Ferric hydrogen sulphate as an effective reusable heterogeneous solid acid catalyst by Fatah H. Alhassan; Robiah Yunus; Umer Rashid; Kamaliah Sirat; Aminul Islam; H.V. Lee; Yun H. Taufiq-Yap (pp. 182-187).
Display Omitted► The catalyst was prepared through replacement reaction (sulfation). ► The high activity of the catalyst was described to strong acidity. ► Fe (HSO4)3 is able to convert simultaneously TAG and FFA in FAMEs with high yield. ► The maximum yield was achieved as 94.5% at optimized condition. ► It is possible to convert oils with very high FFAs content into FAMEs.Biodiesel production by simultaneous esterification and transesterification of waste oil with methanol has been studied in a heterogeneous system using solid ferric hydrogen sulphate [Fe (HSO4)3] acid catalyst. The catalyst was prepared by displacement reaction followed by calcination at 400°C for 3h. The prepared catalyst was characterized using X-ray diffraction (XRD), Fourier transform infrared spectrometer (FT-IR), Brunner-Emmett-Teller surface area measurement (BET), thermal gravimetric analyzer (TGA) and temperature-programmed desorption of NH3 (TPD - NH3). Furthermore, the dependence of the conversion of mixed waste oil on the reactions variables such as the molar ratio of methanol/oil, the amount of catalysts used, reaction temperatures, reusability were also investigated. The catalyst was reused many times with slight loss in activity and the maximum yield of 94.5% was achieved at the optimized conditions of reaction temperature of 205°C; stirring speed of 350rpm, 1:15 molar ratio of oil to alcohol and 1% w/w catalyst loading.
Keywords: Biodiesel; Ferric hydrogen sulphate; Esterification; Transesterification; Mixed waste vegetable oil; Reusable
Isobutane dehydrogenation over the mesoporous Cr2O3/Al2O3 catalysts synthesized from a metal-organic framework MIL-101 by Huahua Zhao; Huanling Song; Leilei Xu; Lingjun Chou (pp. 188-196).
Display Omitted► Non-ordered mesoporous Cr2O3/Al2O3 catalysts were synthesized using MIL-101. ► The isobutene selectivity achieved to 93.2% at the isobutane conversion 60.1%. ► The reactivity was maintainable during the ten dehydrogenation-regeneration cycles. ► The activity and selectivity relied on surface Cr3+ species and Cr3+/Cr6+ value. ► The catalyst showed more stable activity compared with the conventional catalyst.The reactivity of isobutane dehydrogenation over a series of non-ordered mesoporous chromia/alumina (Cr2O3/Al2O3) catalysts with large specific surface area (149.4–381.6m2g−1) and high pore volume (0.77–1.24cm3g−1), synthesized using a metal-organic framework MIL-101 as a molecular host and chromium precursor, aluminium isopropoxide (Al( i-OC3H7)3) as the aluminium precursor, were studied in detail. The chromium species were highly dispersed over the catalyst with chromia loading up to 10wt.%. The specific surface area of the catalyst decreased, whereas the amount of surface Cr3+ species and the mole ratio of Cr3+ and Cr6+ species (Cr3+/Cr6+) increased with the increasing chromia loadings (5–25wt.%) and calcination temperature (500–900°C), respectively. The addition of potassium to the catalyst system greatly promoted isobutene selectivity and catalyst stability. The catalyst with 1.5wt.% K2O and 10wt.% Cr2O3 loadings calcined at 800°C was found to exhibit the highest isobutane conversion 60.1% with the isobutene selectivity up to 93.2% among all the catalysts. The maintainable catalytic reactivity demonstrated the high stability of the catalyst in ten dehydrogenation-regeneration cycles. Moreover, it was proposed that the Cr3+ species was mainly the active site and catalytic selectivity was depended on the surface Cr3+/Cr6+ value over the catalyst. The catalyst presented much more stable dehydrogenation activity compared with the conventional catalyst. Consequently, this study presents a feasible way to facile synthesis of the mesoporous MOF-derived Cr2O3/Al2O3 catalysts with high stability and good catalytic reactivity over isobutane dehydrogenation.
Keywords: Chromia/alumina; Isobutane dehydrogenation; Mesoporous; Metal-organic framework; MIL-101
Oxidative dehydrogenation of ethylbenzene over La0.8Ba0.2Fe0.4Mn0.6O3− δ perovskite oxide catalyst by Kei Mukawa; Fumitaka Sumomozawa; Eiichi Kikuchi; Ryo Watanabe; Yasushi Sekine (pp. 197-203).
•Oxidative dehydrogenation of ethylbenzene over La0.8Ba0.2Fe0.4Mn0.6O3− δ perovskite was investigated.•High styrene production activity over LBFMO oxide with steam and gaseous oxygen.•Steam and oxygen work together as oxidants for lattice oxygen vacancy.•Styrene production rate depends on the amount of lattice oxygen in LBFMO.La0.8Ba0.2Fe0.4Mn0.6O3− δ (LBFMO) perovskite oxide has been found to be an active catalyst for oxidative dehydrogenation of ethylbenzene working with a characteristic Mars–van Krevelen redox mechanism in which steam functions as an oxidant. Results of this study showed that LBFMO oxide exhibited higher activity in the presence of both steam and gaseous oxygen compared with that of steam redox system. The reaction rate of oxidative dehydrogenation of ethylbenzene was zero-th order in oxygen partial pressure and 1.3 order in the amount of the surface lattice oxygen, which demonstrates that the reaction proceeded with redox system and the activity was determined mainly by the available amount of surface lattice oxygen. Kinetics of regeneration of the lattice oxygen from both steam and gaseous oxygen were also investigated, which confirmed that steam and gaseous oxygen mutually function as the oxidant for lattice vacancy on LBFMO. Results of thermogravimetric analysis showed that the available amount of the lattice oxygen in the presence of both steam and gaseous oxygen was 115mmolmol-cat−1, almost twice as high as that in steam alone (63mmolmol-cat−1). High activity in the presence of both steam and oxygen is attributable to the fact that these can simultaneously perform as the oxidant leading to a rich amount of the surface lattice oxygen of LBFMO oxide during the reaction.
Keywords: Oxidative dehydrogenation; Redox properties; Perovskite oxides; Lattice oxygen
Role of CeO2 support for Pd-Cu bimetallic catalysts for oxygen-enhanced water gas shift by Junichiro Kugai; Elise B. Fox; Chunshan Song (pp. 204-214).
Display Omitted► O2 addition enhances water gas shift (WGS) more on Pd-Cu/CeO2 than Pd-Cu/Al2O3. ► Kinetics shows chemistry in H2O activation differs between Pd-Cu on CeO2 and Al2O3. ► CeO2 surface area appears in kinetics as the number of H2O activation sites. ► High surface area CeO2 and O2 addition increase the capacity for H2O activation. ► Infrared spectra of adsorbed CO x and TPR evidence strong metal–ceria interaction.CeO2-supported metal is one of the efficient CO shift catalysts for hydrogen production for compact polymer electrolyte membrane fuel cells (PEMFCs). The present study focuses on the role of support in oxygen-enhanced water gas shift (OWGS) in which a small amount of oxygen is added to a reformate gas to promote WGS. Pd-Cu bimetallic catalysts on various CeO2 supports were prepared and their catalytic activities and physicochemical properties were investigated in comparison with Al2O3-supported catalyst. CeO2-supported catalysts showed not only better performance, but also pronounced enhancement of WGS upon O2 addition to the feed compared to Al2O3-supported catalyst. In kinetic study, the higher CO fractional order with CeO2-supported catalysts than Al2O3-supported counterpart revealed H2O participates in the reaction much more sensitively to CO partial pressure on the former, which further shows H2O is readily activated with CeO2. By the same CO fractional order for all the CeO2-supported catalysts, difference in CeO2 properties was shown to appear in the OWGS rate as the site number for H2O activation. The comparable apparent activation energy ( E a) for Al2O3-supported and CeO2-supported catalysts regardless of the large difference in turnover rate also corroborates that the rate is expressed by the number of the H2O activation sites. The upper limit of turnover rate above 90m2/g of CeO2 surface area was attributed to a change in the rate-controlling factor from H2O activation to CO activation (CO diffusion or CO oxidation ability inherent to metal species). The reducibility of PdO-CuO species measured by TPR and the surface carbonyl/carbonate ratio measured by FT-IR in CO atmosphere were contrastive between Al2O3-supported and CeO2-supported catalysts, which suggested strong interaction at metal–ceria interface. XRD and field emission SEM image revealed that Pd-Cu bimetallic particles uniformly disperse on support by changing the particle size depending on ceria surface property and structure with minor Cu segregation. Ceria properties thus influence both dispersion of Pd-Cu species and reducibility (metal–support interaction) to control H2O activation. Transient pulse studies on clean catalyst surface revealed WGS proceeds via association of the two surface adsorbates of short lifetime, but CO was never converted on pure metal, which corroborates metal–ceria interface is indispensable for high H2O activation.
Keywords: Oxygen-enhanced water gas shift (OWGS); Water gas shift (WGS); Pd; Cu; Metal catalyst; CeO; 2; -supported Pd-Cu; Bimetallic catalysts
A multiphase reaction medium including pressurized carbon dioxide and water for selective hydrogenation of benzonitrile with a Pd/Al2O3 catalyst by Hiroshi Yoshida; Yu Wang; Satomi Narisawa; Shin-ichiro Fujita; Ruixia Liu; Masahiko Arai (pp. 215-222).
•Water and CO2 are useful for selective hydrogenation of nitrile to primary amine.•Water suppresses the reaction between primary amine and imine intermediate.•Water prevents the catalyst from being deactivated by carbamate accumulation.•CO2 molecules interact with cyano group of benzonitrile decreasing its reactivity.The hydrogenation of benzonitrile was studied with a Pd/Al2O3 catalyst in the presence of pressurized CO2 and water. This multiphase reaction system was effective for the selective production of the desired primary amine of benzylamine with no deactivation of the catalyst. The enhanced selectivity to the primary amine resulted from its transfer into water phase, which prevented the primary amine from reacting with an intermediate of imine into the secondary amine in the organic phase (benzonitrile). In addition, interactions of CO2 molecules with the primary amine could also increase its selectivity. In the absence of water, the catalyst was deactivated by the accumulation of a carbamate salt on the surface of catalyst. But this deactivation was avoided by the addition of water because the salt was soluble in water and it did not deposit on the catalyst existing at interfacial layer between the water and organic phases.
Keywords: Benzonitrile; Selective hydrogenation; Carbon dioxide; Water; Multiphase reaction
Study of the synergistic interaction between nickel, gold and molybdenum in novel modified NiO/GDC cermets, possible anode materials for CH4 fueled SOFCs by D.K. Niakolas; M. Athanasiou; V. Dracopoulos; I. Tsiaoussis; S. Bebelis; S.G. Neophytides (pp. 223-232).
Display Omitted► Ni–Au–Mo/GDC powders are investigated as possible anodes for CH4 fueled SOFCs. ► Formation of bimetallic Ni–Au and trimetallic Ni–Au–Mo solid solution. ► Synergistic interaction between Ni, Au, Mo on the structural properties and the catalytic performance. ► C tolerance under CH4 dissociation and steam reforming conditions. ► Superior C tolerance and selectivity to H2 and CO of the binary Au–Ni/GDC catalyst.The present study concerns the structural and physicochemical characterization of novel Au–Mo–NiO/GDC cermets, alongside with measurements of their carbon tolerance. This is an investigation on whether commercially available NiO/GDC powder that is modified with Au and/or Mo can yield possible electrocatalysts as anodes for CH4 fueled SOFCs. Specifically, the performed preparation methods of deposition-precipitation and deposition-coprecipitation permitted the modification of a commercial electrocatalyst and lead to cermets that exhibit different reaction kinetics for the catalytic dissociation of CH4 and different performance for CH4 steam reforming. The most interesting structural findings were observed in the reduced form of the prepared powders, where a bimetallic Ni–Au solid solution is formed in the Au-modified sample. In the ternary composite material a trimetallic Ni–Au–Mo solid solution is formed, which induces a controversial synergistic effect on the sample‘s catalytic performance. On the other hand, the presence of Au compared to Mo shows the best combination of results in terms of structural properties, carbon tolerance and selectivity to the desirable products of H2 and CO, for the reaction of CH4 steam reforming.
Keywords: Ni/GDC; Gold and/or Molybdenum doping; Synergy; CH; 4; dissociation; CH; 4; Steam reforming; Carbon deposition
Iron oxide nanoparticles supported on pyrolytic graphene oxide as model catalysts for Fischer Tropsch synthesis by Huabo Zhao; Qingjun Zhu; Yongjun Gao; Peng Zhai; Ding Ma (pp. 233-239).
•The surface properties of graphene oxides were tuned by thermal treatment.•A series of model catalysts were built by loading iron oxides NPs on them.•Differences in the catalytic behavior in FTS reaction were observed.•It is the chemical groups on the supports affect the catalytic properties.A series of model catalysts were prepared by using monodisperse iron oxide nanoparticles as the metal precursor and pyrolytic graphene oxides as catalyst support. The catalysts have been employed in the Fischer Tropsch Synthesis (FTS) to study the carbon support effect on the iron active phase. Remarkable catalytic discrepancies in FTS activity and product selectivity were observed, with the pyrolytic treatments of the carbon support at 873K significantly improved the catalytic performance, particularly for the C5+ hydrocarbon yields. X-ray adsorption spectroscopy, XPS, Raman and TEM characterization techniques were used to reveal the interaction of carbon support with the active Fe species. It was found that catalytic behavior is closely associated with the evolution of surface oxygen-containing groups on the carbon supports. The carbon supports might affect the iron based FTS catalyst through a poisoning-like route of binding parts of the active sites by surface oxygen.
Keywords: Key words; Fischer Tropsch Synthesis; Iron oxide nanoparticles; Graphene oxide
Sonochemical syntheses of nano-sized dioxomolybdenum complexes: An efficient, selective and reusable heterogeneous nanocatalyst for oxidation of alkenes by Saeed Rayati; Payam Abdolalian (pp. 240-248).
•Dioxomolybdenum nanoparticles have been prepared under ultrasonic irradiation.•The prepared nanocatalysts catalyzed the oxidation of olefins with TBHP.•Heterogeneous and reusable nanocatalysts are utilized.Two Schiff base ligands derived from 2-hydroxy-4-methoxyacetophenone and 2,2′-dimethylpropylenediamine (H2L1) or 1,2-cyclohexanediamine (H2L2) have been synthesized and characterized by physico-chemical and spectroscopic methods. Then dioxomolybdenum complexes have been prepared by reaction of Schiff base ligands and MoO2(acac)2 under ultrasonic irradiation to give nanoparticles of MoL1 and MoL2. FT-IR, UV–vis,1H NMR and13C NMR spectroscopy, elemental analysis, scanning electron microscopy (SEM) and transmission electron microscopy (TEM), were used to characterize and investigate the nanocatalysts. A practical catalytic method for efficient and highly selective oxidation of wide range of olefins with anhydrous tert-butyl hydroperoxide over the prepared molybdenum nanocatalysts was investigated. Under mild reaction conditions, oxidation of cyclooctene led to the formation of corresponding epoxide with a yield of more than 90%. The catalysts were reused five consecutive times without detectable catalyst leaching or significant loss of activity.
Keywords: Epoxidation; Ultrasonic irradiation; Olefins; Heterogeneous nanocatalyst; Molybdenum Schiff base complexes