Performance Of Solid Catalysts Research Articles

ChemInform Abstract: Selectivity Enhancement in Heterogeneous Catalysis Induced by Reaction Modifiers

Abstract The application range of solid catalysts can be greatly extended by reaction or process modifiers , that is by simple addition of an inorganic or organic compound to the reaction mixture. The modifier, used in catalytic amounts, ideally interacts strongly with the active sites in a fashion which induces favorable changes in the outcome of the reaction. Evolution of the actual modified metal catalyst during reaction and the importance of in situ characterization in understanding these processes are illustrated using the examples of promotion by metal ions and nitrogen-containing bases. The major part of the review describes the advantages and limitations of employing N-base modifiers for tuning the performance of solid catalysts. Reactions discussed include chemo-, stereo-, enantio- and diastereoselective hydrogenations over metal catalysts, aerobic oxidation of alcohols with Pt and Pd, and epoxidation of allylic alcohols with titania–silica mixed oxides and alkyl hydroperoxides.

Preparation of microspherical α-zirconium phosphate catalysts for conversion of fatty acid methyl esters to monoethanolamides

The performance of solid catalysts and catalyst supports is generally believed to be dependent on their morphology, surface area, and architecture. In order to fully exploit their attractive properties in actual practical applications, layered zirconium phosphate materials should be fabricated into macroscopic form. Here, we report the fabrication of microscopic spheres of α-zirconium phosphate (α-ZrP) by a spray-drying process. The layered α-ZrP nanoparticles were originally obtained using a synthesis route involving separate nucleation and aging steps (SNAS). The resulting products are composed of nanosize α-ZrP particles aggregated into solid microspheres with a diameter of 5–45 μm and a sphericity of 0.80. After calcination at 573 K, surface area of 43.8 m 2/g could be obtained for α-ZrP microspheres, which is larger than that of the α-ZrP powder after similar thermal treatment (36.2 m 2/g). Furthermore, the number of acidic sites of the α-ZrP microspheres is greater than for the α-ZrP powder due to its unique textual properties and higher surface area. The acylation reaction of fatty acid methyl esters (methyl stearate) with ethanolamine to form monoethanolamides was chosen as a probe reaction to evaluate the catalytic activity of the resulting microspherical α-ZrP materials, which showed high activity compared to the sample in the form of powders, with about 92.9% methyl stearate conversion at 393 K for 12 h. The enhanced performance in the reaction is determined by the large surface area and the increased number of acidic sites in the multiple-scales porosity of α-ZrP microspheres.

Solid Catalysts on the Nanoscale: Design of Complex Morphologies and Pore Structures

AbstractHeterogeneous Catalysis is undoubtedly a key technology in modern chemical industry. Nowadays, most processes in chemical production are catalyzed by solid catalysts. It is thus not surprising that researchers worldwide try to improve existing catalysts or to develop completely new ones. The performance of solid catalysts is determined by their composition but to a great extent also by morphological properties. Control of particle shape and pore topology are thus crucial factors for high performance catalysts. Many interesting approaches have been reported in recent years and the present contribution tries to summarize some of them. The choice of materials and preparation procedures is not comprehensive by a long way, but represents a selection of highly interesting approaches, including bottom‐up approaches as well as post‐synthesis modifications.

Controlling the performance of solid catalysts

Controlling the performance of solid catalysts

固体触媒の工学的問題

固体触媒の工学的問題