Kinetic research and optimized particle size for high-performance of CdS NP photocatalyst.

The effect of HZSM-5 catalyst particle size on gasoline selectivity in methanol to gasoline conversion process

The objectives of this work are the study for understanding methanol dehydration reaction for produce dimethyl ether. By emphasize, the usage zeolite catalysts which in this work was ZSM-5 catalyst. Moreover, in this experiment was divided in two parts that the first was effect of Si/Al atomic ratios and second was effect of particle sizes on dimethyl ether generate performance of zeolite catalysts. From methanol dehydration reaction test with in the temperature range 100 – 300 °C and atmospheric pressure, found that, the zeolite catalyst had lower the value of Si/Al ratio that dimethyl ether selectivity was higher than zeolite catalyst had higher the value of Si/Al ratio. The result show that, performance of dimethyl ether generate depend on the acidity of zeolite catalyst. Moreover, found that in temperature range, At the high temperature that dimethyl ether selectivity was higher than low temperature. And then, when expansion the crystallization time of zeolite catalyst preparation that can observed the smaller particle size of zeolite catalyst. When test methanol dehydration reaction, the smaller particle size of zeolite catalyst performance better than the bigger particle size. And then, investigation about effect of crystallinity of ZSM-5 zeolite catalysts on methanol dehydration found that the optimum crystallinity of ZSM-5 zeolite catalyst is beneficial for catalytic performance.

Effect of particle size on catalytic decomposition of hydrogen peroxide by platinum nanocatalysts

Studies on product distribution of nanostructured iron catalyst in Fischer–Tropsch synthesis: Effect of catalyst particle size

Utilization of e-waste as a silica source for the synthesis of the catalyst support MCM-48 and highly enhanced photocatalytic activity of supported titania nanoparticles

Particle size effects in Fischer-Tropsch synthesis by Co catalyst supported on carbon nanotubes

Reaction performance of the sorption enhanced reforming (SER) process for the production of hydrogen was studied using commercial dolomite as inexpensive solid CO2 absorbent. The combined reforming, shift, and CO2 separation reactions were studied using a laboratory-scale fixed-bed reactor as a function of temperature, feed gas composition, dolomite type, and dolomite and catalyst particle sizes. Reactor was loaded with a mixture of calcined dolomite (≈ 23g) and a commercial reforming catalyst (NiO/Al2O3, ≈ 10g). Temperature was varied from 550 to 650°C at 15 atm. Feed gas composition was varied from 6 to 20% CH4/balance N2 and steam, with a feed H2O/CH4 ratio = 4. Two sources of dolomite were used; Rockwell and Stonelite. Particle sizes of dolomite and catalyst were 75>dp>150 μm and 300>dp>425 μm, respectively and were inversely varied. Results show that at 550°C Ca(OH)2 formation is possible, thus reducing the available CaO for carbonation, negatively affecting the performance of the SER system, while 650°C reached the SER thermodynamic equilibrium (TE). The use of dolomite approached the TE of the feed gas compositions studied, disregarding of its source. Kinetic effects observed in the tests suggest that small dolomite and large catalyst particles favor the decrease of CO2 diffusion effects.

Electrochemical reduction of carbon dioxide: IV dependence of the Faradaic efficiency and current density on the microstructure and thickness of tin electrode

Catalytic properties of bimetallic NiCoB nanoalloy catalysts for hydrogenation of p-chloronitrobenzene

Zinc glutarates were synthesized from zinc oxides with varying purities via different stirring routes. The particle size and structure of these zinc glutarates were determined by wide‐angle X‐ray diffraction, transmission electron microscopy, and the laser particle size analyzer technique. The results demonstrated that the crystallinity and crystalline perfectness of zinc glutarate are the crucial factors that affect the catalytic activity for the copolymerization of carbon dioxide (CO2) and propylene oxide (PO). Additionally, the catalyst with a small particle size dramatically increased the yield of the copolymerization between CO2 and PO. High‐molecular‐weight and regular molecular structure poly(propylene carbonate)s (PPC)s were obtained from CO2 and PO with the synthesized zinc glutarates. Very high catalytic activity of 160.4 g polymer/g catalyst was afforded. The NMR technique revealed that the PPC copolymer exhibits an exact alternating copolymer structure. The relationships between the crystallinity and the particle size of catalyst with the catalytic activity are correlated and discussed. © 2002 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 40: 3579–3591, 2002

The effect of HZSM-5 catalyst particle size on kinetic models of methanol to gasoline conversion

ABSTRACTAn horizontal hot-wall MOCVD reactor was used to prepare palladium and platinum catalysts supported on alumina. A conventional impregnated Pt on alumina catalyst was prepared as comparison. The solids were characterized by XRD, Auger spectroscopy, HREM and H2-TPR. The operation conditions of the MOCVD reactor were fixed preparing several Pd catalysts until to find the appropriate deposition zone. The particle size of Pt catalysts prepared by MOCVD was at about 7 nm compared with 6 ran obtained with the Pt impregnated catalyst, measured by XRD. The HREM image of the Pt MOCVD catalyst showed a narrower particle size ranging from 1 to 4 nm. After calcination three Pt compounds were detected by TPR, which were attributed to PtO, PtO2and Pt-Al2O3interaction in MOCVD preparation. Additionally, a clear reduction of surface oxygens of alumina was also observed.

Controlled synthesis of uniform cup-stacked carbon nanotubes for energy applications

Polypropylene was produced in gas phase and liquid phase using different supported Ziegler‐Natta‐catalysts. Sorption behaviour of propylene in polymer particles was studied gravimetrically. The analyzed polymer fractions have average diameters between 250 and 875 µm. Generally it was found that the effective diffusion coefficient is increasing with increasing size of polymer particles. With electron microscopy a change of polymer particle morphology with particle size and type of catalysts was observed.

The simple reactor model developed for the fluidized-bed methanator PEDU gives reasonably good parity plots for six PEDU tests using six different catalysts. This model can be used to predict the performance of the pilot plant methanator and as a building block in any computerized simulation of the BI-GAS process for process development, design or optimization purposes. Some refinements could be made to the model to accommodate changes in mode of operation and additional knowledge gained concerning the hydrodynamic properties of the catalyst bed. The kinetic model, based upon a first-order rate equation to describe the catalyst behavior in the PEDU, also appears to be satisfactory as to its utilization in the reactor model. Further refinements could be made to yield a more mechanistically accurate expression, which would include the effects of non-first-order kinetics and deactivation on CO conversion and of selectivity on product distribution. The selectivity of molybdenum-containing catalysts for the water-gas shift reaction has been shown to be significantly higher than that of cobalt-containing catalysts. This suggests that catalysts containing molybdenum might be more suitable for processes in which the water-gas shift reaction must be combined with methanation. However, this increase in selectivity appears to be coupled withmore » a reduction in overall activity. Further investigation is neededto determine whether this reduction is real or merely the result of an imbalance between particle size and pore structure of the molybdenum-containing catalyst, which has resulted in mass-transfer limitations in those catalysts tested so far.« less