Ordered mesoporous silica, with high porosity was used to immobilize glucoamylase via adsorption and covalent binding. Immobilization of glucoamylase within mesoporous silica was successfully achieved, resulting in catalytically high efficiency during starch hydrolysis. In this study, mesoporous silica was functionalized by co-condensation of tetraethoxysilane (TEOS) with organosilane (3-aminopropyl) triethoxysilane (APTES) in a wide range of molar ratios of APTES: TEOS in the presence of triblock copolymer P123 under acidic hydrothermal conditions. The prepared materials were characterized by Small angle XRD, Nitrogen adsorption -desorption and 29 Si MAS solid state NMR. N2 desorption studies showed that pore size distribution decreases due to pore blockage after functionalization and enzyme immobilization. Small angle XRD and 29 Si MAS NMR study reveals mesophase formation and Si environment of the materials. The main aim of our work was to study the catalytical activity, effect of pH, temperature, storage stability and reusability of covalently bound glucoamylase on mesoporous silica support. The result shows that the stability of enzyme can be enhanced by immobilization.
A series of spinels having the general formula CuCr2-xFexO4 with x = 0.25, 0.75, 1.25, 1.75 were prepared by co-precipitation method. The catalysts were characterized by various physico-chemical methods like XRD, BET, SEM, EDX and TPD. The reaction of aniline with methanol was studied in a fixedbed reactor system as a potential source for the production of various methyl anilines. It was observed that systems possessing low 'x' values are highly selective and active for N-monoalkylation of aniline leading to N-methylaniline. Reaction parameters were properly varied to optimize the reaction conditions for obtaining N-methylaniline selectively and in better yield. Among the systems CuCr1.75Fe0.25O4 is remarkable due to its very high activity and excellent stability. Under the optimized conditions Nmethylaniline selectivity exceeded 91%. CuCr1.25Fe0.75O4 gives better conversion than CuCr1.75Fe0.25O4 in CuCr2-xFexO4 series. The Lewis acid sites of the catalysts are mainly responsible for the good catalytic performance.
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