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Applied Catalysis A, General (v.332, #2)
Species and temperature profiles in a differential sphere bed reactor for the catalytic partial oxidation of n-octane by G.J. Panuccio; L.D. Schmidt (pp. 171-182).
A method is developed for measuring temperature and species profiles for the catalytic partial oxidation (CPO) of n-octane in a fixed bed of noble metal coated spheres. The results show that there is first a very short oxidation zone in the front of the catalyst where fuel and O2 are consumed and a longer reforming zone downstream.▪A method is developed by which temperature and species profiles are measured for the catalytic partial oxidation (CPO) of n-octane in a differential manner in a fixed bed of Pt and Rh-coated α-alumina spheres with a minimum resolution of 1mm (or ∼0.4g) of catalyst over a wide range of feed stoichiometries. Results indicate that two regions of catalytic activity are present in the bed: a short (∼1mm) oxidation zone in the front of the bed and a longer reforming zone downstream. The lengths of the reforming and oxidation zones are dependent on the stoichiometry of the reactor feed. O2 is consumed rapidly on both Rh and Pt catalysts; however, full O2 conversion is reached faster on Rh than on Pt. Both steam reforming and dry (CO2) reforming are observed in the bed downstream of the oxidation zone, but steam reforming is more extensive because higher conversions of H2O are observed than CO2 on both Rh and Pt catalysts. The conversion of H2O and CO2 in the reforming zone is always higher on Rh than on Pt, therefore Rh is a better reforming catalyst than Pt. Low molecular weight hydrocarbons like methane and ethylene are more readily reformed than octane. Results also indicate that alumina sphere beds are better supports for syngas production than alumina foam monoliths.
Keywords: Catalytic partial oxidation; Rhodium; Platinum; Octane; Profile
Selective tert-butylation of phenol over molybdate- and tungstate-promoted zirconia catalysts by Benjaram M. Reddy; Meghshyam K. Patil; Gunugunuri K. Reddy; Baddam T. Reddy; Komateedi N. Rao (pp. 183-191).
Selective tert-butylation of phenol over molybdate- and tungstate-promoted zirconia catalyst.Molybdate- and tungstate-promoted zirconia catalysts exhibit a good substrate conversion and excellent para selectivity in the vapour phase tert-butylation of phenol at normal atmospheric pressure. Characterization of the catalysts by various physicochemical techniques reveals that the incorporated promoter cations show a significant influence on the surface and bulk properties of the zirconia.▪The catalytic performance of molybdate- and tungstate-promoted zirconia catalysts for tert-butylation of phenol with tert-butanol as alkylating agent has been investigated. The reaction was carried out at 433–493K in a fixed bed micro-reactor at normal atmospheric pressure. The promoted zirconia catalysts were synthesized by immersing the finely powdered hydrous zirconium hydroxide in aqueous ammonium heptamolybdate or ammonium metatungstate solution and subsequent oven drying and calcination at 923K. The hydrous Zr(OH)4 was prepared from aqueous zirconium oxychloride by hydrolysis with a dilute aqueous ammonia solution. To investigate the structural and textural properties, we characterized the synthesized catalysts by X-ray powder diffraction (XRD), BET surface area, temperature programmed reduction (TPR), temperature programmed desorption (TPD) of ammonia, scanning electron microscopy (SEM), Raman spectroscopy (RS), and FT-infrared spectroscopy (FTIR) techniques. All the characterization results reveal that the incorporated promoter cations show a significant influence on the surface and bulk properties of the ZrO2. In particular, the impregnated cations stabilize the metastable tetragonal phase of zirconia at ambient conditions and enhance the total number and the strength of the acid sites. A good substrate (phenol) conversion and excellent product selectivity were obtained over the promoted zirconia catalysts.
Keywords: Alkylation; Phenol; Solid acid; Characterization; Tetragonal zirconia
A novel immobilized cobalt(II)/copper(II) bimetallic catalyst for atom transfer radical polymerization (ATRP) of methyl methacrylate by Zhongxi Huang; Yongming Zhang; Hong Li; Yangang Liu (pp. 192-199).
Cross-linked poly(acrylic acid) (PAA) resin immobilized Co(II)/Cu(II) bimetallic catalyst could well control over the polymerization of methyl methacrylate (MMA). After polymerization, the catalyst could be easily removed, resulting in the concentration of transition-metal residues in polymer product lower than 5ppm. Both catalytic activity and controllability were retained by the recycled catalyst. ▪A new immobilized catalytic system, cross-linked poly(acrylic acid) (PAA) resin immobilized cobalt(II)/copper(II) bimetallic catalyst, was successfully employed for atom transfer radical polymerization (ATRP) of methyl methacrylate (MMA). Well-defined poly(methyl methacrylate) (PMMA) with low polydispersity (PDI=1.27) was synthesized using PAA/Co(II)/Cu(II) catalyst without any additional ligand or soluble deactivator. As the immobilized catalyst could be effectively separated from the polymer solution by simple centrifugation after polymerization, colorless PMMA (Co residue<1ppm, Cu residue ∼4ppm) was achieved. Both main catalytic activity and good controllability over polymerization were retained by the recycled catalyst after reused several times. The catalyst was characterized by SEM, EDX, TGA and ESR techniques. The polymerization reaction mechanism was presented.
Keywords: ATRP; Immobilized catalyst; Cobalt catalyst; Bimetallic catalyst; Catalyst residue
Solid phosphoric acid catalysed conversion of oxygenate containing Fischer–Tropsch naphtha by Thomas N. Mashapa; Arno de Klerk (pp. 200-208).
The effect of Fischer–Tropsch derived oxygenates on olefin oligomerisation over a solid phosphoric acid (SPA) catalyst is mainly related to increased catalyst hydration and the conversion of strong pyrophosphoric acid (H4P2O7) sites to weaker orthophosphoric acid (H3PO4) sites. At 180°C, 3.8MPa and WHSV of 1.5h−1, oxygenate conversion to hydrocarbons is 99%. The main oxygen-containing product was water, although alcohols produced by olefin hydration and ketone decomposition to carboxylic acids were also observed. With increasing catalyst hydration the oligomer yield decreased. The extent of inhibition was related to the oxygenate concentration, the nature of the oxygenates and the nature of the olefins. Leaching of phosphoric acid was negligible and not a significant factor in determining catalyst activity. It was shown that olefin oligomerisation on SPA follows a Langmuir–Hinshelwood mechanism.The influence of Fischer–Tropsch derived oxygenates on olefin oligomerisation over a solid phosphoric acid (SPA) catalyst is described (180°C, 3.8MPa). Oxygenate conversion to hydrocarbons is 99%, which increased catalyst hydration and the conversion of strong H4P2O7 sites to weaker H3PO4 sites. This caused a decrease in oligomer yield.▪
Keywords: Oligomerisation; Solid phosphoric acid; Fischer–Tropsch refining; Oxygenates
Structure and reactivity of silica-supported zirconium sulfate for esterification of fatty acid under solvent-free condition by Joon Ching Juan; Jingchang Zhang; Mohd Ambar Yarmo (pp. 209-215).
Silica-supported zirconium sulfate was studied by using esterification of fatty acid under solvent-free conditions as a probe reaction, and the reactivity was found to be strongly loading related. The reaction also shows that the silica-supported ZS exhibits a higher activity than that of bulk ZS and conventional solid acid catalysts. ▪The structure and reactivity of silica-supported zirconium sulfate (ZS) with 10–50wt% loading prepared by impregnation method are studied by using X-ray diffraction (XRD), surface area measurement, TG, FTIR-pyridine and XPS. It is found that most of ZS in samples is well dispersed on the support. However, at loading higher than 40wt%, ZS exist as small agglomerate crystalline particles with an average size around 23.8–32.1nm, calculated by XRD results. Based on various characterizations on various techniques, it may be concluded that ZS forms interaction with the silica support, which is responsible for the high dispersion and the enhanced acidity of these systems. The effects of different loading on the reactivity of silica-supported ZS is studied by using esterification of fatty acid under solvent-free conditions as a probe reaction, and the reactivity is found to be strongly loading related. The reaction also shows that the silica-supported ZS exhibits a higher activity than that of bulk ZS and conventional acid resins.
Keywords: Zirconium sulfate; Silica; Structure; Esterification; Oleic acid
Preparation of Au/Mg xAlO hydrotalcite catalysts for CO oxidation by Ching-Tu Chang; Biing-Jye Liaw; Ching-Tsuen Huang; Yin-Zu Chen (pp. 216-224).
Gold was dispersed and stabilized on a solid base of Mg xAlO hydrotalcite by a modified deposition precipitation method to obtain a good catalyst for CO oxidation. The calcination temperatures of the Mg xAlO support and the Au/Mg xAlO catalyst dominated the ratio of gold states (Au3+/Au0) that influenced the activity of the catalyst.▪Gold catalysts of CO oxidation, supported on a solid base of Mg xAlO ( x=Mg/Al molar ratio) hydrotalcite, were prepared by a modified deposition precipitation method. The effect of various parameters that are involved in the preparation of catalysts were studied, including the pH and the concentrations of HAuCl4 in the initial solution, the Mg/Al molar ratio and the calcination temperature of the Mg xAlO support as well as the calcination temperature of the Au/Mg xAlO catalyst. The catalysts were characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), ultraviolet–visible (UV–vis) and X-ray photoelectron spectroscopy (XPS) analyses. The pH and the HAuCl4 concentrations in the initial solution, and the Mg/Al molar ratio of Mg xAlO affected the pH in the final solution, and determined the real gold loading in the resulting catalyst. The calcination temperatures of the Mg xAlO support and the Au/Mg xAlO catalyst dominated the ratio of gold states (Au3+/Au0) on the catalyst. The optimal catalyst, 2%Au/Mg2AlO(100), was obtained using the following preparation parameters: (1) 1×10−3M HAuCl4, (2) pH 2 (without adjusting pH) in the initial solution, (3) Mg/Al=2 (Mg2AlO) calcined at 100°C as a support and (4) 2%Au/Mg2AlO catalyst calcined at 100°C. This investigation confirms that not only gold loading of the catalyst is important, the ratio of gold states (Au3+/Au0) is also critical in determining the activity of the catalyst for CO oxidation.
Keywords: CO oxidation; Catalyst preparation; Gold catalysts; Hydrotalcite; Mg; x; AlO
Development of ceria-supported sulfur tolerant nanocatalysts: Pd-based formulations by Abdul-Majeed Azad; Martin J. Duran; Amanda K. McCoy; Martin A. Abraham (pp. 225-236).
Performance of nominally doped nanoscale ceria-supported palladium catalyst matrices in sulfur-laden fuel streams was evaluated. Addition of metal oxide additives provides higher stability and sulfur-tolerance.▪The conversion of logistics fuels (JP-5, JP-8, Jet-A and diesel) to hydrogen by steam reforming is attractive but poses great challenge since these fuels contain sulfur up to about 3000ppm leading to catalyst deactivation due to sulfur poisoning. In this paper, we report the fabrication of nominally doped nanoscale ceria-supported palladium catalyst matrices for their performance evaluation in sulfur-laden fuel streams. Systematic structural and microstructural characterization of the catalysts was carried out before and after the steam reforming and simulated experiments in sulfur containing streams (50ppm
Keywords: Nanoscale doped-ceria supports; Noble metals; Metal oxides; Logistic fuels; Steam reforming; Electron microscopy; Sulfur-tolerance; Coking phenomenon
Catalytic growth of structured carbon from chloro-hydrocarbons by Antonio Nieto-Márquez; Jose Luis Valverde; Mark A. Keane (pp. 237-246).
Cl substitution of ethane and ethene was found to increase the carbon yield generated via Ni/SiO2 promoted decomposition. Conversion of C2H4 and C2H6 produced high aspect ratio carbon nanofibres, C2H4Cl2, C2H3Cl3 and C2H2Cl2 yielded nanofibres with an apparent periodicity to give a bamboo-like appearance while the decomposition of C2HCl3 resulted predominantly in nanosphere formation.▪The catalytic growth of structured carbon from C2H4, C2H6, C2H2Cl2, C2HCl3, C2H4Cl2 and C2H3Cl3 promoted by Ni/SiO2 in the presence of H2 over the range 673K≤ T≤1073K has been examined. The presence of Cl served to enhance carbon deposition where carbon yield (at T<850K) increased in the order C2H62H42H4Cl22H3Cl32H2Cl2≤C2HCl3; at T>900K, carbon yield converged for C2H3Cl3, C2H2Cl2 and C2HCl3. Carbon efficiencies (fraction of carbon in the inlet feed that is converted to a solid carbon product) in excess of 96% have been achieved. Conversion of C2H4 also generated C2H6 (hydrogenation) as a secondary reaction while CH4 (hydrogenolysis) production from C2H4 and C2H6 was observed where T>900K. The chloro-hydrocarbon to carbon reaction generated HCl as the only inorganic product with no evidence of Cl2 or chloro-organics in the product stream, i.e. Ni/SiO2 solely promotes a composite dehydrochlorination/decomposition. The nature of the carbonaceous product has been characterized by a combination of TEM, SEM, XRD, BET area and temperature programmed oxidation (TPO). Carbon yield from C2H6 and C2H4 passed through apparent maxima at 773 and 993K, respectively, and took the form of high aspect ratio graphitic nanofibres with a central hollow core and diameters in the range 5–180nm. Carbon deposition from C2H4Cl2, C2H3Cl3 and C2H2Cl2 increased with increasing temperature to deliver essentially a carbon yield invariance where 898K≤ T≤1023K. The carbon fibres from the latter reactants exhibit a “segmented” or “bamboo-like” structure with diameters up to 560nm. In complete contrast, catalytic decomposition of C2HCl3 resulted predominantly in nanosphere formation. These nanospheres exhibited a wide diameter range (35–680nm) with a conglomeration or clustering and are characterized by a lesser structural (graphitic) order than the nanofibres produced from C2H4 and C2H6.
Keywords: Chloroethylene(s); Chloroethane(s); Ni/SiO; 2; Catalytic decomposition; Carbon growth; Carbon nanofibres; Carbon nanospheres
Titanium phosphonate-supported palladium catalyst for the hydrogenation of acetophenone with one-phase catalysis and two-phase separation by Yeling Ji; Xuebing Ma; Xinjun Wu; Qiang Wang (pp. 247-256).
A novel inorganic polymer titanium 2-[ N-(2-hydroxy-1,2-diphenylethyl)]aminoethylphosphate and its supported palladium complex had been synthesized and characterized by IR, XPS, XRD, TG, SEM and TEM. The catalyst TiP–Pd was applied to the catalytic hydrogenation of acetophenone with one-phase catalysis and two-phase separation. And the selectivity to 1-phenylethanol and ethylbenzene was up to 93.3% and 100%, respectively under mild conditions.▪A novel inorganic polymer titanium 2-[ N-(2-hydroxy-1,2-diphenylethyl)]aminoethylphosphate (TiP) and its supported palladium complex (TiP–Pd) had been synthesized and characterized by IR, XPS, XRD, TG, SEM and TEM. The catalyst TiP–Pd was applied to the catalytic hydrogenation of acetophenone in homogeneous ethanol phase and can be conveniently recovered with above 97% recovery by adding equal volume of petroleum ether. In the catalytic hydrogenation of acetophenone, the selectivities to 1-phenylethanol and ethylbenzene was up to 93.3% at −20°C and 100% at −20 to 40°C, respectively under atmospheric hydrogen pressure. The catalyst TiP–Pd can be reused 11 times without the leaching of palladium ion and the sharp loss of catalytic activity.
Keywords: Titanium phosphonate; Homogeneous catalytic hydrogenation; Two-phase separation; Acetophenone; Palladium
Performance of Mo-Bi-Co-Fe-K-O catalysts prepared from a sol–gel solution containing a drying control chemical additive in the partial oxidation of propylene by Bu Young Jo; Eun Ju Kim; Sang Heup Moon (pp. 257-262).
The performance of Mo12Bi1.0Co4.4Fe1.0K0.07O x catalysts, which were prepared by a sol–gel method using a drying control chemical additive (DCCA), in propylene oxidation was investigated. The DCCA-modified catalysts exhibited the activity of propylene oxidation and selectivity for the production of acrolein and acrylic acid higher than those of the catalyst prepared without using DCCA. Propionic acid increased the selectivity to the greatest extent due to decreased amounts of Brönsted-type acidic sites.▪The performance of Mo12Bi1.0Co4.4Fe1.0K0.07O x mixed-metal oxide catalysts in the partial oxidation of propylene was investigated. Such catalysts were prepared by precipitating catalyst components from a sol–gel solution that contained a drying control chemical additive (DCCA). The addition of DCCA, selected from among glycerol, formamide and propionic acid, to a sol–gel solution did not change the crystallite phases of the prepared catalysts, which included MoO3, Bi2Mo3O12, Bi2MoO6, CoMoO4, Fe2O3, and α-FeMoO4, but did decrease the crystallite sizes, thereby increasing the catalytic activity. The DCCA-modified catalysts also exhibited selectivity values for the production of acrolein and acrylic acid that were higher than that of the catalyst prepared without using the additive. Among three DCCAs tested in this study, propionic acid added in a proper amount increased the selectivity to the greatest extent because propionic acid decreased the amounts of Brönsted-type acidic sites on the catalyst, which are detrimental to the selectivity.
Keywords: Sol–gel method; Drying control chemical additive; Propylene oxidation
Oxidation of ethanol to acetaldehyde over Na-promoted vanadium oxide catalysts by Ricardo J. Chimentão; Jose E. Herrera; Ja Hun Kwak; F. Medina; Yong Wang; Charles H.F. Peden (pp. 263-272).
Na-promoted VO x catalysts supported on MCM-41 and TiO2 were investigated for the partial oxidation of ethanol. Sodium addition increases the dispersion of the VO x species decreasing their reducibility. In the case of the catalysts supported on MCM-41, these modifications were mirrored by a change in the activity and selectivity to acetaldehyde. A model in which sodium affects dispersion, reducibility and acidity of supported VO x has been proposed. ▪Sodium-promoted vanadium oxide catalysts supported on MCM-41 and TiO2 (anatase) were investigated for the partial oxidation of ethanol to acetaldehyde. The catalysts were prepared by incipient wetness impregnation with a vanadium oxide content of 6wt.%. The experimental characterization was performed by X-ray diffraction (XRD), N2 adsorption, temperature-programmed reduction (TPR), and diffuse reflectance UV–vis. Temperature-programmed oxidation (TPO) was also used to identify carbon deposits on the spent catalysts. The presence of sodium plays a strong role in the dispersion and reducibility of the vanadium species as detected by TPR analysis and optical absorption spectroscopy. While sodium addition increases the dispersion of the VO x species, its presence also decreases their reducibility. Additionally, TPO of the spent catalysts revealed that an increase in the Na loading decreases the carbon deposition during reaction. In the case of the catalysts supported on MCM-41, these modifications were mirrored by a change in the activity and selectivity to acetaldehyde. Additionally, on the VO x/TiO2 catalysts the catalytic activity decreased with increasing sodium content in the catalyst. A model in which sodium affects dispersion, reducibility and also acidity of the supported-vanadia species is proposed to explain all these observations.
Keywords: Vanadium oxide; Oxidation; Ethanol; MCM-41; TiO; 2; Na; DRS-UV–vis; XRD; TPO
Catalysts for the thermo-catalytic cracking (TCC) process: Interactions between the yttria in yttria-doped alumina aerogel and the mono-oxide MoO3, CeO2, and bi-oxide MoO3–CeO2 species by N. Al-Yassir; R. Le Van Mao (pp. 273-288).
Mo and Ce species interact with both alumina and yttria in yttria-doped alumina aerogel system. We have found that there were stronger interactions between Mo and the support, upon using yttria-doped alumina aerogel. On the contrary, there were weaker interactions upon using conventional alumina or alumina aerogel. Similar observations were observed with Ce based system. Hence, Mo–Ce interactions were significantly enhanced over the yttria-doped alumina aerogel surface.▪The influence of yttria used as a doping agent for catalyst support, on the dispersion and the resistance to sintering of MoO3, CeO2 and bi-oxide MoO3–CeO2 species in the TCC catalysts has been investigated. Characterization techniques used included N2 adsorption, X-ray diffraction, Raman, thermogravimetric analysis, and iso-electric point (IEP).It was explicitly found that yttria-doped alumina aerogel is by far more capable of homogenously dispersing the active molybdenum species and significantly retarding their sintering at quite high-calcination temperature than conventional alumina and alumina aerogel. Characterization results of supported mono-oxide MoO3 catalysts have clearly indicated that the fraction of (surface) tetrahedral monomolybdate species increases in the detriment of crystalline MoO3 as we varied the support from conventional alumina to yttria-doped alumina aerogel with increasing amounts of the yttria loading. This can be attributed to the incorporation of yttria into alumina aerogel network, which led to a change in the support surface charge (IEP) and subsequently the stability of surface molybdate species. The dispersion degree of ceria (substituted ceria) on supported mono-oxide CeO2 was improved as well, upon using yttria-doped alumina aerogel. Such improvement was attributed to the formation of stronger Ce–Y–O bond, and/or the formation of CeO2–Y2O3 solid solution. In the bi-oxide MoO3–CeO2, characterization results have indicated the presence of surface interaction between Mo and Ce, probably through the formation of surface “Mo–O–Ce” type phase between the dispersed ceria and the molybdate monolayer. This interaction, which was highly favourable over yttria-doped alumina surface, contributed significantly to the overall surface stability of Mo–Ce catalysts.
Keywords: Thermo-catalytic cracking (TCC); Supported bi-oxide MoO; 3; –CeO; 2; Yttria-doped alumina aerogel; Improved dispersion-retarded sintering of Mo species; “Mo–Ce–O” type interaction phase
New synthesis of tungsten carbide particles and the synergistic effect with Pt metal as a hydrogen oxidation catalyst for fuel cell applications by Yoshinori Hara; Noriko Minami; Hajime Matsumoto; Hiroaki Itagaki (pp. 289-296).
Some new tungsten carbides (WC) were synthesized by the carburizing of tungsten nitrides (W2N) and tungsten sulfides (WS2) as precursors, which were prepared from different starting materials. WC containing Pt metal was prepared and evaluated as an anode catalyst for the electrochemical hydrogen oxidation. The mass activity of the Pt-WC catalyst system was superior to the current commercial Pt catalyst in spite of the reduction of the use of Pt metal to one-tenth. ▪Some new tungsten carbides (WCs) were synthesized by the carburizing of tungsten nitrides (W2N) and tungsten sulfides (WS2) as precursors, which were prepared from different starting materials. The carbides were characterized by BET surface area measurements, XRD, SEM and TEM. WCs synthesized by these procedures afforded higher surface areas than those obtained from a conventional direct carburization of WO3. WC containing a small amount of Pt metal was prepared by a wet impregnation method and evaluated as an anode catalyst for the electrochemical hydrogen oxidation reaction. The property of WC which is associated with its synthetic pathway exerted a significant influence on the catalyst performance. The activity of a binary Pt-WC catalyst was greatly improved by choosing a suitable WC and modifying the preparative method. As a result, it turned out that the mass activity of the Pt-WC catalyst system was superior to the current commercial Pt catalyst although only one-tenth the amount of Pt metal was used. It is thought that there is a synergistic effect between Pt and WC in terms of activity, leading to a drastic reduction in the use of Pt metal. A Pt-WC catalyst system may be regarded as one of the candidates for cost-effective catalysts for the future fuel cell devices.
Keywords: Tungsten carbide; Hydrogen electro-oxidation; Platinum; Synergistic effect
Nano-TiO2 sols immobilized on porous silica as new efficient photocatalyst by P. Pucher; M. Benmami; R. Azouani; G. Krammer; K. Chhor; J.-F. Bocquet; A.V. Kanaev (pp. 297-303).
The catalyst prepared by impregnation of 6.0nm TiO2 particles in nanoporous silica granulate at mass loading of ∼0.55% demonstrates the highest photocatalytic efficiency of 0.45 (TCE test). The catalyst specific surface of 330m2/g is almost not affected by the particle impregnation. Our results show a high potential of this nanostructured catalyst for applications in reactive gas cleaning.▪Nanocoatings of an extremely small thickness below 10nm prepared from metastable chemically active TiO2 colloids demonstrate both high mechanical stability and internal efficiency in photocatalysis [M. Benmami, K. Chhor, A. Kanaev, Chem. Phys. Lett. 422 (2006) 552]. To overcome their inherently low absorption, porous substrates of high UV transparency have to be used. We have studied influence of substrate on the nanocatalyst performance. The catalyst prepared by impregnation of 6.0nm TiO2 particles in nanoporous silica granulate at mass loading of ∼0.55% demonstrates the highest photocatalytic efficiency of 0.45 (TCE test). The catalyst specific surface of 330m2/g is almost not affected by the particle impregnation. Our results show a high potential of this nanostructured catalyst for applications in reactive gas cleaning.
Keywords: Nanocoatings; Photocatalysis; TiO; 2; nanoparticles; Sol–gel process; Porous silica
SnCl2·2H2O-catalyzed efficient synthesis of β-acetamido ketones and β-acetamido ketoesters under solvent-free conditions by Lingaiah Nagarapu; Rajashaker Bantu; Rakesh Puttireddy (pp. 304-309).
A simpler protocol has been developed for the preparation of β-acetamido ketones and β-acetamido ketoesters by a one-pot reaction using SnCl2·2H2O as a catalyst in a solvent-free media at room temperature. The present methodology offers several advantages such as excellent yields, simple procedure, short reaction times (1–2.5h) and milder conditions. ▪SnCl2·H2O has been found to be useful and highly efficient for the preparation of β-acetamido ketones and β-acetamido ketoesters by a one-pot reaction of aryl aldehydes, enolisable ketones, acetyl chloride and acetonitrile in a solvent-free media at room temperature. The present methodology offers several advantages such as excellent yields, simple procedure, short reaction times (1–2.5h) and milder conditions.
Keywords: One-pot synthesis; β-Acetamido ketones; β-Acetamido ketoesters; Enolisable ketones; Simple procedure
Comparative study of steam reforming of methane, ethane and ethylene on Pt, Rh and Pd supported on yttrium-stabilized zirconia by Patrick O. Graf; Barbara L. Mojet; Jan G. van Ommen; Leon Lefferts (pp. 310-317).
In the present paper steam reforming of methane, ethane and ethylene was compared on Pt and Rh supported on yttrium-stabilized zirconia (YSZ). The order of activity for the hydrocarbons on Rh was C2H6>C2H4>CH4. On Pt, methane reacted faster than the C2-hydrocarbons: CH4>C2H6, C2H4.▪In the present paper steam reforming of methane, ethane and ethylene was compared on Pt, Rh and Pd supported on yttrium-stabilized zirconia (YSZ). Both reactivity and product distribution changed with the use of different catalysts. The order of activity for the hydrocarbons on Rh was C2H6>C2H4>CH4. On Pt, methane reacted faster than the C2-hydrocarbons: CH4>C2H6, C2H4. The lowest coking tendency was observed on Pt/YSZ. Pd/YSZ showed a high tendency to coke formation and blocked the reactor.Pt/YSZ produced synthesis gas (CO and H2) only for all hydrocarbons. However, more importantly, in this study all significant reactions during ethane steam reforming on Rh/YSZ have been clarified. Methane formation in addition to synthesis gas production on this catalyst was assigned to hydrogenolysis of ethane by consecutive conversion of hydrogen produced in ethane steam reforming.
Keywords: Steam reforming; Methane; Ethane; Ethylene; Pt; Rh; Yttrium-stabilized zirconia