SYNTHESIS AND CHARACTERIZATION OF ZEOLITES USING SATURATED CYCLIC AMINES AS STRUCTURE-DIRECTING AGENTS

A synthesis route to obtain high-silica MOR using cyclic amines as str ucture-directing agents is described. As far as we know, the use of th ese structure-directing agents for the synthesis of high silica MOR is not described elsewhere. The pore size of the synthesised products (z eolite MOR, FER and mixtures of zeolite MOR and FER), was related to t he ring size of the organic structure-directing agent in the reaction mixture. Various saturated cyclic amines were used. Pure high-silica M OR of high crystallinity was obtained via direct synthesis using hexa- and heptamethyleneimine. In addition, high-silica FER was prepared am ong others with pyrrolidine. A mixture of MOR and FER was synthesised in the presence of piperidine. The materials were characterised and th e catalytic performance of the high silica MOR was evaluated. Catalyst s prepared with direct synthesis of high-silica MOR as base material w ere active in the isomerisation of pentane and hexane. Presumably the direct-synthesis high-silica MOR samples were somewhat less active tha n conventional MOR (dealuminated by leaching to the same Si/Al ratio S AR), because of a lower accessibility of acid sites. The lower accessi bility of the direct synthesis mordenite may be due to amorphous mater ial. Other explanations are that extra-framework aluminum species were formed during calcination and preferential aluminium siting in these MOR crystals.