Chaudhari catalysts

A hst of 74 GLS reacdions with hterature references has been compiled by Shah Gas-Liquid-Solid Reactions, McGraw-HiU, 1979), classified into groups where the solid is a reactant, or a catalyst, or inert. A hst of 75 reactions made by Ramachandran and Chaudhari (Three-Phase Chemical Reactors, Gordon and Breach, 1983) identifies reactor types, catalysts, temperature, and pressure. They classify the processes according to hydrogenation of fatty oils, hydrodesulfurization, Fischer-Tropsch reactions, and miscellaneous hydrogenations and oxidations. 

Ramachandran, RA. and R.V. Chaudhari, Three Phase Catalystic Reactors. 1983 Gordon and Breach. 

Recently, Chaudhari compared the activity of dispersed nanosized metal particles prepared by chemical or radiolytic reduction and stabilized by various polymers (PVP, PVA or poly(methylvinyl ether)) with the one of conventional supported metal catalysts in the partial hydrogenation of 2-butyne-l,4-diol. Several transition metals (e.g., Pd, Pt, Rh, Ru, Ni) were prepared according to conventional methods and subsequently investigated [89]. In general, the catalysts prepared by chemical reduction methods were more active than those prepared by radiolysis, and in all cases aqueous colloids showed a higher catalytic activity (up to 40-fold) in comparison with corresponding conventional catalysts. The best results were obtained with cubic Pd nanosized particles obtained by chemical reduction (Table 9.13). 

T. K. Das, W. Conner, G. Jacobs, J. Li, K. Chaudhari and B. H. Davis, Fischer-Tropsch synthesis Effect of water on activity and selectivity for a cobalt catalyst, Stud. Surf. Sci. Catal., 2004, 147, 331-336. 

Production of polymers contributes to pollution during synthesis and after use. A polymer produced by microorganisms is already a commercial product (Biopol). Unfortunately, however, cellular synthesis remains limited by the cost of downstream processing and the fact that the synthesis is aqueous-based, and it is impossible to perform the synthesis in the absence of a solvent. Recent research describes an enzyme-catalyzed polymer synthesis in which there is no solvent. This bulk polymerization mirrors conventional synthesis but eliminates the needs for extremes of temperature and corrosive acid catalysts. This represents the first rapid and efficient synthesis of polyesters from bulk polymerization under ambient conditions with very low concentrations of a biocatalyst (Chaudhary et al., 1997). 

This reaction is catalyzed by Pd-Al203 catalyst at 30 °C and is considered to be first order with respect to oxygen (Hopper et al., 2001 Ramachandran, and Chaudhari, 1980). The rate coefficient for this reaction is km = 0.0177 cm3/g s. 

D.D. Chaudhari and R.A. Rajadhyaksha, Alkylation of o-xylene by styrene using superacid catalysts, Ind.Engg.Chem.Res., 26 (1987) 1743-45. 

Chaudhari, R.V., Bhanage, B.M., Deshpande, R.M. and Delmas, H. (1995) Enhancement of interfacial catalysis in a biphasic system using catalyst-binding ligands. Nature, 373, 501. 

FIG. 19-31 Some examples of bubble column reactor types, (a) Conventional bubble column with no internals. (6) Tray bubble column, (c) Packed bubble column with the packing being either an inert or a catalyst. [From Mills, Ramachandran, and Chaudhari, Multiphase Reaction Engineeringfor Fine Chemicals and Pharmaceuticals, Reviews in Chemical Engineering, 8(1-2), 1992, Figs. 2, 3, and 4.]... 

Shingote, S.K., Kelkar, A.A., Borole, Y.L., Joshi, P.D., and Chaudhari, R.V. 2008. Ultrasound promoted asymmetric transfer hydrogenation of ketones using Ru(ll)arene/amino alcohol catalyst system. Ultrasonics Sonochemistry, 15 289-93. 

The kinetic modeling study of l-(4-isobutylphenyl)ethanol (IBPE) carbonylation nsing a homogeneous palladium complex has been reported by Chaudhari. The three key steps (formation of the active substrate formation of the active catalyst catalytic carbonylation of active substrate) were studied in detail. The average carbonylation rate depends on several factors, so a dynamic analysis, where the concentrations of both the catalyst species and the intermediates were varied, was carried out. 

Of primary interest for the industrial application of monolith reactors is to compare them with other conventional three-phase reactors. Two main categories of three-phase reactors are slurry reactors, in which the solid catalyst is suspended, and packed-bed reactors, where the solid catalyst is fixed. Generally, the overall rate of reactions is often limited by mass transfer steps. Hence, these steps are usually considered in the choice of reactor type. Furthermore, the heat transfer characteristics of chemical reactors are of essential importance, not only due to energy costs but also due to the control mode of the reactor. In addition, the ease of handling and maintenance of the reactor have a major role in the choice of the reactor type. More extensive treatment of conventional reactors can be found in the works by Gianetto and Silveston [11], Ramachandran and Chaudhari [12], Shah [13,14], Shah and Sharma [15], and Trambouze et al. [16], among others. 

The kinetics of the new commercial process of hydroformylation of allyl alcohol was studied by Chaudhari in the temperature range from 60 to 80 °C [114]. The rate of reaction is first order in catalyst concentration and 1.5th order in hydrogen partial pressure. The dependence on p CO) does not differ from that observed in the hydroformylation of nonfunctionalized olefins. The reaction is retarded at higher substrate concentrations (> 1.25 mol/L). This substrate inhibition is not fully understood on the molecular level. The apparent activation energy for the oxo reaction of allyl alcohol was found to be 94 kJ/mol. 

Fukuda and Kusama [11] successfidly partially hydrogenated butynediol by enq>loying Pd-CaCOj and quinoline as poison. In later work of Fukuda [3], the combination effect of lead acetate and quinoline on Pd/BaCOs gave partial hydrogenation as weU. hi order to selectively produce m-butenediol, Chaudhari et al. [12] reported the use of Lindlar catalyst doped with zinc acetate that gave partial reduction with selectivity as high as 99.8% toward m-butenedioL... 

In a report Chaudhari et al. [18] have shown that the rate of biphasic hydroformylation can be enhanced severalfold by using a catalyst binding ligand which facili-... 

Choudhary, VR Rane, VH Chaudhari, ST. Influence of various promoters on the basicity and catalytic activity of MgO catalysts in oxidative coupling of methane. Catalysis Letters, 1990 6, 95-98. 

---