Preparation of ZSM-5 thin film on cordierite honeycomb by solid state in situ crystallization

Thin films of ZSM-5 zeolite were prepared on porous cordierite honeycombs b y a solid state in situ crystallization method and were characterized by XR D, FTIR, SEM and nitrogen gas adsorption. The zeolite films were formed by coating the zeolite precursor sol on the cordierite honeycomb substrate and gelling it in the surface pores of the substrate. This gel was then conver ted into ZSM-5 by heating the coated substrate in an autoclave without addi ng solution. The amount of coating was increased by forming an interfacial layer of microporous silica on the cordierite substrate by acid leaching. T he maximum specific surface area of the honeycomb coated with zeolite film was 249 m(2)/g. Recoating the substrate with zeolite film was effective not only in increasing the amount of zeolite film and its surface area but als o in reducing the macropores in the honeycomb surface. The zeolite film was found to retain its porous properties up to the calcining temperature of 9 00 degreesC. The zeolite film is considered to be formed by a vapor transpo rt mechanism initiated by the water included in the gel. (C) 2001 Elsevier Science B.V. All rights reserved.