Synthesis and characterization of mesoporous mcm 41 molecular sieves their catalytic activity in organic functional group protection and transformations

Abstract

The word catalysis was coined by Berzelius in the year 1835 Since newlinethen the concept of catalysis adopted by scientists and technologists leads to newlinerevolution in chemical industry A catalyst augments the rate of a chemical newlinereaction without being consumed in the reaction Because of its ability to newlinespeed up some reactions and not others a catalyst enables a chemical process newlineto work more efficiently and often with less waste Homogeneous catalysts newlineare effective for oxidation reactions but are poisonous and their separation newlinefrom the product in reusable form is difficult In this respect there is no newlinedoubt that heterogeneous catalysts play a crucial role in the development of newlineenvironmentally benevolent processes in petroleum chemistry and in fine newlinechemicals synthesis Among the heterogeneous catalysts the microporous newlinematerials like zeolites are the most widely used materials in industries newlineHowever the performance of the zeolitic systems is limited by diffusional newlineconstraints associated with smaller pore diameter below 10 A In addition newlinezeolites are more prone to deactivation by coke formation due to slow newlinediffusion To a certain extent it is possible to overcome this problem using newlinealuminophosphate ALPO microcrystalline materials with pore dimensions newlineup to 13 A However these materials suffer from limited thermal stability as newlinewell as negligible catalytic activity due to framework neutrality Therefore to newlineovercome these drawbacks the research has focused on the enlargement of newlinethe pore size into the mesopore range which allows larger molecules to enter newlinethe pore system The researchers at the Mobil Research and Development newlineCorporation synthesized mesoporous materials 1992 through the discovery newlineof M41S family of silicate and aluminosilicates These mesostructured newlinematerials are experiencing explosive growth as potential candidates as newlinecatalysts supports and adsorbents The mesoporous molecular sieve Si newlineMCM41 was found as a well suited catalyst in heterogeneous reaction newlinebecause their large surface area allows for generating large number of