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Applied Catalysis A, General (v.421-422, #)
A review of selective catalytic reduction of nitrogen oxides with hydrogen and carbon monoxide by Hideaki Hamada; Masaaki Haneda (pp. 1-13).
Display Omitted► Supported Pt and Pd catalysts show high activity for SCR of NO with H2 (H2-SCR). ► The presence of SO2 promotes the catalytic activity of Ir/SiO2 and Rh/SiO2 for H2-SCR. ► Only Ir serves as an effective catalytically active metal for SCR of NO with CO (CO-SCR). ► Ir/SiO2 is active for CO-SCR in the presence of SO2, which keeps Ir in the active metal state. ► The activity of Ir/SiO2 is promoted by WO3 addition, for which Ir-WOx is the active species.The selective reduction of NO with hydrogen (H2-SCR) and CO (CO-SCR) over platinum group metal catalysts in the presence of O2 is overviewed. In the case of H2-SCR, Pt and Pd show high activity at low temperatures. The acidity of the support material greatly affects NO reduction activity and selectivity to N2/N2O. Although the activity of Ir and Rh for H2-SCR is low, coexisting SO2 in the reaction gas considerably promotes NO reduction. The best support for Ir and Rh is SiO2. Li and Zn additives improve the activity of Ir/SiO2 and Rh/SiO2, respectively, by maintaining the active reduced metal state. For CO-SCR, on the other hand, Ir is almost the only active metal species. Coexisting SO2 is also essential for CO-SCR on Ir/SiO2 to occur. The role of SO2 for both H2-SCR and CO-SCR on Ir/SiO2 is to keep Ir in the form of the catalytically active Ir metal state. The additions of WO3 and Nb2O5 considerably promote the activity of Ir/SiO2 for CO-SCR, catalyzing CO-SCR even in the absence of SO2. Ir metal interacting strongly with W oxide is the active species on WO3-promoted Ir/SiO2. Furthermore, the addition of Ba improves the performance of Ir/WO3/SiO2 catalyst.
Keywords: Nitrogen oxide; Selective catalytic reduction; Hydrogen; Carbon monoxide; Platinum; Palladium; Iridium; Rhodium
Amino-functionalized mesoporous silica as base catalyst and adsorbent by Toshiyuki Yokoi; Yoshihiro Kubota; Takashi Tatsumi (pp. 14-37).
.Display Omitted► Amino-functionalized mesoporous silicas were synthesized by post-synthesis grafting and direct co-condensation methods. ► Amino-functionalized mesoporous silica prepared was also prepared via anionic surfactant templated route. ► Various applications of amino-functionalized mesoporous silica are described.Mesoporous molecular sieves with size-tunable mesopores have been well developed and have attracted a great deal of attention because of their controllable structures and compositions, which make them suitable for a wide range of applications in catalysis, adsorption, separation, chromatography, etc. The pore size of mesoporous silica is large enough to accommodate a variety of large molecules, and the high density of silanol groups on the pore wall is beneficial to the introduction of functional groups with a high coverage. Actually, various kinds of surface modifications have been conducted for providing new functions for the surfaces. Among various functional groups, the introduction of the amino groups onto the mesopores has enabled us to use amino-functionalized mesoporous materials as solid-base catalysts and adsorbents. Meanwhile, “anionic surfactant templated mesoporous silica (AMS)” has been synthesized via a novel templating route for preparing mesoporous silicas based on the self-assembly of anionic surfactants and inorganic precursors in the presence of aminosilane or quaternized aminosilane as a co-structure-directing agent. AMSs are synthetically interesting not only for their structural diversity, including chiral properties, but also for the chance of functionalizing the pore surface by removing the surfactant by solvent extraction, resulting in the formation of the mesoporous silica with aminopropyl groups intact. Thus obtained amino-functionalized AMS can be applied to solid-base catalysis, adsorption, drug delivery, etc.This review gives an overview on the recent development of amino-functionalized mesoporous silica. In particular, the difference in the state and catalytic activity of amino groups between the functionalized mesoporous silicas synthesized via anionic and cationic surfactants templating routes is featured. Interesting applications of amino-functionalized mesoporous silica besides solid-base catalyst are also described.
Keywords: Amino-functionalized mesoporous silica; Adsorbent; Solid-base catalyst
Hydroprocessing on chromium-containing metal sulfide catalysts by T.C. Ho; W.H. Pan; A.J. Jacobson; R.R. Chianelli (pp. 38-47).
Display Omitted► The hydrodenitrogenation activity and selectivity of MoS2 can be greatly enhanced by chromium. ► Chromium and iron are synergistic co-promoters for enhancing the HDN activity of MoS2. ► The predominant phase in unsupported chromium-promoted MoS2 catalysts comprises nanocrystalline MoS2 and amorphous Cr2S3.We showed previously that unsupported catalysts prepared from amine thiomolybdates incorporated with bivalent metals (Fe, Ni, Co) are highly active for hydrodenitrogenation (HDN) and hydrodesulfurization (HDS). In particular, an iron-promoted molybdenum sulfide catalyst gives a much higher HDN-to-HDS activity ratio than commercial supported catalysts. The present study examines trivalent chromium as a promoter for MoS2. The catalyst precursors are synthesized via two routes: one involves olation, the other chelation. Tests with a catalytic cycle oil show that the behaviors of the Cr-containing catalysts prepared from the two routes are qualitatively similar. Chromium is a more effective HDN promoter than iron. The Fe0.5Cr0.5Moy (1≤ y≤1.5) trimetallic sulfide is more active and selective for HDN than FeMo and CrMoy bimetallic sulfides. The predominant phase in the chromium-containing catalysts comprises nanocrystalline MoS2 and amorphous Cr2S3.
Keywords: Hydrodesulfurization; Hydrodenitrogenation; Hydrogenation; Chromium promoted molybdenum sulfide catalysts; Olation; Trimetallic sulfide catalysts
Improving the selectivity to HDS in the HDT of synthetic FCC naphtha using sodium doped amorphous aluminosilicates as support of CoMo catalysts by David J. Pérez-Martínez; Eric M. Gaigneaux; Sonia A. Giraldo (pp. 48-57).
Display Omitted► It is possible to obtain HDS selective materials without losing the HDS activity. ► This was achieved by finely tuning the acid–base properties of CoMo catalysts. ► CoMo catalysts supported on sodium-modified aluminosilicates were used. ► Selective formation of weak Brönsted was observed in the best catalyst. ► β-CoMoO4 crystalline species were also obtained in the best catalyst.CoMo catalysts supported on sodium-doped amorphous aluminosilicates (ASA) with different Si/(Si+Al) ratios were prepared. The catalytic performance of these catalysts in the HDT of synthetic FCC naphtha was compared with the one of a CoMo catalyst supported on pure alumina, as well as with another one supported on sodium-modified alumina. The catalysts results were also compared with the ones of CoMo catalyst supported on ASA without sodium. The catalysts were characterized by XRF, XRD, Raman, as well as their textural and acid properties. The sodium introduction simultaneously with the variation of the Si/(Si+Al) ratio conducts to obtain a catalyst (15% Si/(Si+Al), 3wt.% Na) with, on the one hand, an Mo oxide species distribution with an important participation of β-CoMoO4 crystalline species and, on the other hand, a selective formation of weak Brönsted acid sites. As a consequence of this especial balance between the acid properties and the oxidic Mo-surface-species distribution, this catalyst presented an activity similar to the one of the CoMo/Al2O3, but with improvements in the selectivity to HDS. Additionally, it was also encountered that when CoMo catalysts supported on materials of predominantly acidic nature are used, the linear olefins inhibit more the HDS activity than the branched ones, whereas the contrary effect was encountered when supports of a predominantly basic nature are used.
Keywords: FCC naphtha; Selectivity to the HDS; Amorphous aluminosilicates; Hydrogenation of olefins; Acid properties
Oxidative dehydrogenation of n-octane using vanadium pentoxide-supported hydroxyapatite catalysts by Venkata D.B.C. Dasireddy; Sooboo Singh; Holger B. Friedrich (pp. 58-69).
Display Omitted► Oxidative dehydrogenation of n-octane using vanadium supported hydroxyapatites. ► V2O5 with varying loadings 2.5–15.0wt% was supported on hydroxyapatites. ► Octenes are the major products at all temperatures and vanadium loadings. ► Selectivity of aromatics increases with increase in temperature and vanadium loading. ► C2–C7 cyclization is favoured in the formation of aromatics.Vanadium pentoxide, with loadings varying from 2.5 to 15wt%, was supported on hydroxyapatite (HAp) by the wet impregnation technique. The materials were characterised by techniques such as X-ray diffraction (XRD), inductively coupled plasma-optical emission spectroscopy (ICP-OES), BET, FTIR, SEM, transmission electron microscopy (TEM), temperature programmed reduction (TPR) and temperature programmed desorption (TPD). From XRD and IR analyses, vanadium is found in the vanadium pentoxide phase for the lower loadings, whereas for weight loadings in excess of 10%, an additional pyrovanadate phase exists. 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 vanadium concentration and the phase composition of the catalyst. Good selectivity towards octenes was achieved using the 2.5wt% V2O5 on HAp loaded catalyst. There was a marked decrease in octene selectivity and a significant increase in the formation of C8 aromatics when higher loadings of vanadium were used. At a conversion of 24% at 450°C, the 15wt% V2O5 on HAp showed a selectivity of 72% towards octenes. A maximum selectivity of 10% for C8 aromatics was obtained using the 15wt% V2O5 on HAp catalyst at a conversion of 36% at 550°C.
Keywords: Hydroxyapatite; V; 2; O; 5; n; -Octane; 1-Octene; o; -Xylene; Oxidative dehydrogenation
Comparison between catalytic and catalytic photo-assisted propene hydration by using supported heteropolyacid by Giuseppe Marcì; Elisa Isabel García-López; Leonardo Palmisano (pp. 70-78).
Display Omitted► Impregnated commercial TiO2 and SiO2 with H3PW12O40 (POM) has been prepared. ► POM/TiO2 and POM/SiO2 are efficient catalysts in hydration of propene to 2-propanol. ► Reaction was carried out in gas–solid regime and soft conditions. ► The contemporary presence of heat and UV light improved the activity of the solids. ► The presence of TiO2 under UV irradiation improved the POM performance.Hybrid materials have been prepared by impregnation of the heteropolyacid H3PW12O40 on commercial TiO2. The polyoxometalates (POM) amount deposited was 15, 30, 50 and 70% with respect to the weight of the TiO2 support. Moreover two samples containing a POM amount of 15, and 50% with respect to the weight of SiO2 were also prepared for the sake of comparison. All prepared samples were efficient catalysts for the hydration of propene to 2-propanol in gas–solid regime at atmospheric pressure and at temperatures ranging between 50 and 85°C. The study carried out on the hybrid TiO2 based materials evidenced that, as far as the catalytic activity is concerned, exists an optimum in the amount of POM. Notably the contemporary presence of heat and UV light improved the activity of the POM/TiO2 and POM/SiO2 materials, although POM/TiO2 showed better catalytic and catalytic photo-assisted activity than POM/SiO2. POM species played a key role in both the catalytic and photo-assisted catalytic reactions, due to its surface acidity and ability to form strong oxidant species under UV irradiation. The presence of TiO2 under UV irradiation improved the heteropolyacid performance supplying conduction band electrons to the POM.
Keywords: Heteropolyacid; Propene; Hydration; 2-propanol; Photo-assisted reaction; TiO; 2
Isomerization of endo-dicyclopentadiene using Al-grafted MCM-41 by Ji-Jun Zou; Yan Xu; Xiangwen Zhang; Li Wang (pp. 79-85).
Display Omitted► Al-grafted MCM-41 shows higher activity than Hβ. ► Weak Lewis acid sites are the active site. ► Sample with Si/Al ratio of 8 shows highest selectivity of 85%, with conversion of 70%. ► The deactivated catalyst is easily regenerated by calcination.The isomerization of endo-dicyclopentadiene ( endo-DCPD) using Al-grafted MCM-41 was studied as an industrial practical synthesis route for exo-DCPD. The catalyst was prepared with post-synthesis grafting method, characterized by XRD, N2 adsorption/desorption,27Al and29Si MAS NMR, in-situ pyridine adsorption IR and NH3-TPD. The materials retain ordered mesoporous structure and high surface area. Al atoms are preferentially anchored in tetra-coordination, but these in octa-coordination increase significantly in case of high Al content. The amount of Brønsted acid is closely related to the amount of tetra-coordinated Al species whereas that of Lewis acid corresponding to the total Al content. The prepared material shows higher activity than microporous zeolites because its mesoporous structure gives free diffusion and excellent coke tolerance capability. A good correlation between the conversion of endo-DCPD and the amount of Lewis acid was observed. Specifically, the weak Lewis acid sites catalyze the endo- to exo-isomerization, meanwhile the moderate ones account for the [2+2] cycloaddition of two DCDP molecules. Catalyst with Si/Al of 8 is most active due to its highest concentration of weak Lewis acid. Addition of inert solvent, relatively low reaction temperature and high catalyst dosage can improve the isomerization. The deactivated catalyst can be easily regenerated by calcination.
Keywords: Dicyclopentadiene; Isomerization; Al-MCM-41; Mesoporous zeolites
Heterogeneous selective hydrogenation of trans-4-phenyl-3-butene-2-one to allylic alcohol over modified Ir/SiO2 catalyst by He-yan Jiang; Bin Sun; Xu-xu Zheng; Hua Chen (pp. 86-90).
Display Omitted► Heterogeneous enantioselective hydrogenation of trans-4-phenyl-3-butene-2-one is reported. ► Ir/SiO2 stabilized with phosphines and modified by cinchona alkaloids are employed as catalysts. ► Chemoselectivity to α,β-unsaturated alcohol is more than 99%. ► Enantioselectivity to α,β-unsaturated alcohol is up to 46%.The heterogeneous selective hydrogenation of trans-4-phenyl-3-butene-2-one to allylic alcohol, catalyzed by Ir/SiO2 stabilized with phosphines and modified by cinchona alkaloids, was described herein. Under the optimized conditions, the chemoselectivity to α,β-unsaturated alcohol was more than 99% with enantioselectivity up to 46%.
Keywords: Selective catalysis; Iridium; Alkaloids; Trans; -4-phenyl-3-butene-2-one; Supported catalysts
Carbon nanotubes, silica and titania supported heteropolyacid H3PW12O40 as the catalyst for ethanol conversion by A. Micek-Ilnicka; E. Bielańska; L. Lityńska-Dobrzyńska; A. Bielański (pp. 91-98).
Display Omitted► Carbon nanotubes represent an interesting material as mesoporous support. ► Conversion of ethanol on H3PW12O40 supported on carbon nanotubes and oxides was used as the catalytic test reaction. ► Activity of H3PW12O40 on carbon nanotubes was comparable to that heteropolyacid on SiO2 at 460K.The new catalyst: heteropolyacid H3PW12O40 (HPA) supported on carbon nanotubes (CNTs) for ethanol conversion was compared with silica and titania supported heteropolyacid. The ethanol conversion did not depend on the type of the support up to reaction temperature 403K while above 423K ethanol conversion was higher for HPA on CNTs than for unsupported HPA. Generally, the most active catalysts were obtained by using high surface area silica as the support.
Keywords: Ethanol conversion; Carbon nanotubes; Heteropolyacid; Oxide supports
Novel microwave synthesis of ruthenium nanoparticles supported on carbon nanotubes active in the selective hydrogenation of p-chloronitrobenzene to p-chloroaniline by Claudia Antonetti; Mustapha Oubenali; Anna Maria Raspolli Galletti; Philippe Serp; Giuditta Vannucci (pp. 99-107).
Display Omitted► A new route of synthesis of Ru/CNTs catalysts was devised adopting MW irradiation. ► A green mixture of ethanol/water was adopted as solvent/reducing agent. ► The obtained ruthenium nanoparticles have small dimensions and narrow size distributions. ► Good selectivity in the hydrogenation of p-chloronitrobenzene to p-chloroaniline.Carbon nanotubes (CNTs) have been employed for the preparation of supported ruthenium nanoparticles using, for the first time, a low boiling alcohol or a mixture ethanol/water as solvent/reducing agent under microwave irradiation as heating source. These systems were employed as catalysts in the selective hydrogenation of p-chloronitrobenzene (p-CNB) to p-chloroaniline (p-CAN) and resulted efficient systems for the selective reduction of the nitro group in p-CNB under mild reaction conditions (60°C and 4MPa of H2), while the CCl bond remains intact, thus allowing the almost complete substrate conversion with total selectivity to the target product. These supported ruthenium nanoparticles are characterized by small average diameters and narrow particle size distributions, even if synthesized in the absence of any additional stabilizing agents and appear very promising systems also for other catalytic applications.
Keywords: Ruthenium; Nanoparticles; Carbon nanotubes; Microwaves; Hydrogenation; p-Chloronitrobenzene
The effects of carbonaceous species in HZSM-5 on methanol-to-olefin process by Hong Liu; Luming Peng; Nianhua Xue; Xuefeng Guo; Weiping Ding; Weimin Yang; Zaiku Xie (pp. 108-113).
Display Omitted► Transient reaction of12CH3OH/13CH3OH switching is more carefully analyzed. ► Propene and ethene are formed through different paths over high silica HZSM-5. ► High Si/Al ratio of zeolite leads to high propene/ethene ratio in products. ► A partial carbonaceous species in zeolite is active for methanol reactions.An improved transient12CH3OH/13CH3OH switching method is used at steady-state conditions with a computer-controlled multi-position valve to distinguish the formation paths of propene and ethene over HZSM-5 zeolites in the methanol-to-olefin process for understanding the effects of Si/Al ratios and the carbonaceous deposited in the zeolites. By carefully analyzing the isotope distribution in products in short time intervals at transient state, it is demonstrated that a fraction of the carbonaceous species is active and participates in the methanol reactions. On high silica zeolite, the active carbonaceous species are responsible for the production of ethene, while propene is formed mainly through rapid alkene methylation in zeolite channels. High Si/Al ratio of zeolite leads to high ratio of propene to ethene in products of methanol-to-olefin process.
Keywords: Carbonaceous species; Acid density; HZSM-5; MTO; P/E ratio
Hydration of nitriles to amides in water by SiO2-supported Ag catalysts promoted by adsorbed oxygen atoms by Ken-ichi Shimizu; Naomichi Imaiida; Kyoichi Sawabe; Atsushi Satsuma (pp. 114-120).
Display Omitted► Ag particles partially covered with surface oxygen atoms as effective catalysts for hydration of nitriles to amides. ► TOF increases linearly with the coverage of the surface oxygen. ► A surface science driven strategy of catalyst design for green organic synthesis in water.A series of silica-supported silver catalysts with similar Ag loading (5 or 7wt%) but with different preparation methods (calcination in air and reduction by H2 or NaBH4) were prepared, and their structure was characterized by microscopy (STEM), X-ray absorption fine structure (XAFS), and CO-titration of surface oxygen atom. Ag is present as metal nanoparticle with a size range of 17–30nm. Their surface was partially covered with oxygen atoms, and the surface coverage of the oxygen depends on the preparation condition. For hydration of 2-cyanopyridine as a test reaction, turnover frequency (TOF) per surface Ag species is estimated. TOF does not show a good correlation with Ag particle size, but it linearly increases with the coverage of the surface oxygen atoms on Ag particles. The Ag/SiO2 catalyst prepared by H2 reduction at 700°C shows the highest TOF and it acts as effective and recyclable heterogeneous catalyst for selective hydration of various nitriles to the corresponding amides. Kinetic and Raman spectroscopic studies suggest that the surface oxygen atom adjacent to Ag0 sites plays an important role in the dissociation of H2O.
Keywords: Nitriles; Amides; Surface oxygen; Nanoparticles; Silver
Stabilization of ZSM-5 zeolite catalysts for steam catalytic cracking of naphtha for production of propene and ethene by Avelino Corma; Jesús Mengual; Pablo J. Miguel (pp. 121-134).
Display Omitted► Dealumination of ZSM-5 zeolite occurs in steam catalytic cracking of naphtha. ► Si/Al ratio has a little influence on the rate of deactivation due to dealumination. ► Postsynthesis impregnation with phosphorous slow down the zeolite deactivation. ► Optimum amount of phosphorous depends on the Al content of zeolite. ► Introduction of phosphorous affects little the selectivities to ethene and propene.In order to increase ethene and propene, naphtha steam catalytic cracking has been considered. The cracking of C5–C12 n-alkanes with ZSM-5 has been studied in absence and in presence of steam and the influence of the operation variables was studied. Irreversible catalyst deactivation by dealumination also occurs in the reactor when the cracking is carried out in the presence of steam. To diminish steam deactivation, the influence of zeolite Si/Al framework and a postsynthesis treatment by phosphorous have been studied and optimized. Much more stable catalyst can be achieved that result in an increase in activity without penalty for production of ethene and propene.
Keywords: Steam catalytic cracking (SCC); Zeolite dealumination; ZSM-5 hydrothermal stability; Phosphorous stabilized zeolite; Alkenes production; Olefins production; Si/Al ratio
Calcination effect of nanosized ceria in ceria–platinum composite electrode for direct ethylene glycol oxidation by A.A. El-Shafei; A.A. Ibrahim; A.M.A. Ouf (pp. 135-141).
Display Omitted► CeO2 insoluble in acidic media has been prepared using thermal decomposition technique. ► Oxide particle size was found to increase with the calcination temperature. ► At optimum conditions, Pt/CeO2/GC electrode shows superior performance for EG oxidation compared to Pt/GC electrode. ► The activity of the modified electrode depends on calcination temperature as well as CeO2:Pt ratio.CeO2 nonsoluble in H2SO4 has been prepared using thermal decomposition techniques and has been characterized by X-ray. The particle size was found to increase as the calcination temperature increases. Nano crystalline Pt/CeO2/GC composite electrodes were fabricated and examined using SEM, EDX analysis and electrochemical techniques. The reactivity of the modified electrode has been tested for ethylene glycol (EG) oxidation in acidic media using cyclic voltammetric and chronoamperometric technique. The Pt/CeO2/GC electrodes were found to be more reactive towards EG oxidation and more stable against poisoning process in comparison to Pt/GC electrode. The performance of the electrodes was found to depend on the ratio of CeO2:Pt as well as on the calcination temperature during CeO2 preparation.
Keywords: Ethylene glycol oxidation; Nanosized ceria; Pt; Composite electrode
Desulfurization activity of nickel supported on acid-treated activated carbons by Jia-xiu Guo; Juan Liang; Ying-Hao Chu; Ming-Chao Sun; Hua-Qiang Yin; Jian-Jun Li (pp. 142-147).
Display Omitted► Acid treatment can increase the surface area of activated carbon. ► Different acid treatment can influence surface functional groups of activated carbon. ► Nitric acid treatment can increase CO or CO functional groups and Ni dispersion. ► Ni and NiO species coexist on the activated carbon before desulfurization. ► Ni2O3 are observed and Ni and NiO species are disappeared after desulfurization.Activated carbons from coal were treated with different acids and used as carriers. Ni catalysts supported on untreated and treated activated carbons were prepared by the excessive impregnation method and characterized using Brunauer–Emmett–Teller surface area characterization, X-ray diffraction, and X-ray photoelectron spectroscopy. The desulfurization activity of granular catalysts was evaluated at a fixed bed under a simulated gaseous mixture. The results showed the following: (1) the order of desulfurization activity is AC2SO43; (2) the specific surface area of the original activated carbons (723m2/g) is less than that of the activated carbons treated with nitric (831m2/g) and sulfuric acid (803m2/g); (3) acid treatment can affect the surface functional groups of activated carbons, and activated carbons treated with nitric acid can significantly increase CO or CO functional groups, which can enhance the desulfurization performance of the catalysts; and (4) Ni and NiO species coexist in the activated carbons before desulfurization, but after desulfurization, Ni and NiO species disappear and Ni2O3 is observed, indicating that Ni species could be involved in the desulfurization reaction.
Keywords: Activated carbons; Nickel; Desulfurization; Surface functional groups; Acid
Spent automotive three-way catalysts towards CC bond forming reactions by Ewa Mieczyńska; Andrzej Gniewek; Anna M. Trzeciak (pp. 148-153).
Display Omitted► Filters containing airborne matter catalyze efficiently the Heck reaction. ► Spent automotive catalysts are highly active in CC bond forming reactions. ► Isomerization and hydroformylation was performed with spent automotive catalysts. ► The presence of crystalline Rh, Pd and Pt nanoparticles was evidenced by TEM.Spent automotive three-way catalysts, containing Rh, Pd and Pt nanoparticles supported on oxide-based ceramic materials, catalyze the Heck cross-coupling of iodobenzene with butyl acrylate and unsaturated alcohols at 140°C. Under Suzuki reaction conditions, biphenyl was formed with high yield when the same catalysts were applied. Successful hydroformylation of 1-hexene was performed in the presence of PPh3. The catalytic activity of spent automotive three-way catalysts was compared with that of airborne matter collected in the city of Wrocław.
Keywords: Automotive three-way catalysts; Heck reaction; Suzuki reaction; Hydroformylation; Platinum group metals; Metal nanoparticles
Catalytic oxidation of ethylene at low temperatures using porous copper manganese oxides by Eric C. Njagi; Homer C. Genuino; Cecil K. King’ondu; Saminda Dharmarathna; Steven L. Suib (pp. 154-160).
Display Omitted► Copper manganese oxides are highly active catalysts for ethylene oxidation. ► High activity attributed to amounts of Mn4+ species, and compositional homogeneity. ► Incorporation of copper enhances the activity of resultant bimetallic oxides.Amorphous manganese oxide and binary copper manganese oxides were synthesized using the redox method, characterized, and tested in the catalytic oxidation of ethylene. The catalytic activity of the synthesized catalysts toward ethylene oxidation was high (100% conversion of 1.0% C2H4 at 200°C with space velocity of35,000 mL h−1gcat−1) and compared favorably with that of a commercial Hopcalite catalyst. The high catalytic activity was attributed a combination of factors including the poor crystallinity, the high surface areas (≥163m2g−1), porosity, presence of Mn4+ species, and compositional homogeneity of the synthesized copper manganese oxides. Incorporation of copper into the amorphous manganese oxide matrix significantly enhanced the catalytic activity of the resultant bimetallic oxides by increasing the reducibility and ease of removal of lattice oxygen species. The synthesized materials were characterized using FE-SEM, HR-TEM, BET, FAAS, XPS, and TPD methods.
Keywords: Catalytic oxidation; Copper manganese oxide; Ethylene; Volatile organic compounds (VOCs)
Direct formation of propanol from a dilute ethylene feed via reductive-hydroformylation using homogeneous rhodium catalysts at low feed pressures by Brandon A. Rodriguez; William J. Tenn III (pp. 161-163).
.Display Omitted► Reductive Hydroformylation of ethene to propanol with homogeneous rhodium catalysts. ► Performed on dilute feed streams to simulate waste streams currently burned as fuel. ► Several commercially available phosphine ligands explored. ► Tested at a variety of ethylene:hydrogen:CO ratios to identify best feed composition. ► Observed correlations between product selectivity and catalyst decomposition.This work details a system for the direct production of propanol from a dilute ethylene stream by reductive hydroformylation catalyzed by soluble rhodium complexes coordinated to tri-aryl or tri-alkyl phosphines.Typically, in commercial production, normal alcohols are produced from primary olefins via a two step process consisting of hydroformylation of the olefins to aldehydes, followed by subsequent hydrogenation of the aldehydes to the corresponding alcohols. This work describes a method to produce propanol directly from dilute ethylene feeds.In addition, the partial pressures of the syngas used in these experiments are significantly lower (approximately an order of magnitude) than reported for nearly all of the other rhodium catalyzed reductive-hydroformylation systems (0.7–70atm vs. ∼20–700atm).
Keywords: Homogeneous; Catalysis; Hydroformylation; Propanol
Real-time Raman monitoring of liquid-phase cyclohexene epoxidation over alumina-supported vanadium and phosphorous catalysts by E. Mikolajska; V. Calvino-Casilda; M.A. Bañares (pp. 164-171).
Display Omitted► In situ real-time Raman monitors liquid-phase cyclohexene epoxidation. ► Solvent-free epoxidation of cyclohexene with TBHP over Al2O3-supported VPO catalysts. ► Raman monitoring confirms the reaction mechanism of the cyclohexene epoxidation. ► Raman spectroscopy monitors the deactivation of catalysts during reaction. ► Real-time Raman monitoring is more reliable than the use of GC analyses.The solvent-free liquid phase epoxidation of cyclohexene with tert-butyl hydroperoxide over alumina-supported VPO and VPO bulk catalysts has been widely investigated using in situ Raman spectroscopy. Real-time Raman monitoring provides non-invasive insight during epoxidation of cyclohexene in the presence of heterogeneous catalysts in the absence of any solvent. The progress of the reaction was monitored following the changes in intensity of the characteristic Raman bands, which is more reliable than the use of gas chromatography analyses. The results obtained by real-time Raman monitoring confirms the reaction mechanism and provides a mean to monitor the deactivation of catalysts. The interaction between vanadium oxide species and VPO phases generates the active site. Their interaction renders the catalytic system efficient for production of 1,2-epoxycyclohexane.
Keywords: Raman spectroscopy; Cyclohexene epoxidation; Reaction monitoring; In line analysis; VPO catalysts