Zeolites reaction with, phosgene

Fejes et al. [50-54] extensively studied the extractive dealumination of zeolites (mordenite) with acid halides (phosgene, nitrosyl chloride) at 400-600 C. The reaction of H-mordenite with phosgene, monitored by IR spectroscopic determination of the volatile reaction products HCl and C02> was foimd to proceed in three main steps at temperatures above 100 C (Eq. 2a) and 300°C (Eqs.2b and 2 c) ... 

It has been reported that F2, phosgene COCI2, and SiCU can be used for gas-phase dealumination. The commonly used method to obtain dealuminated zeolites involves SiCU (gas)-zeolite (solid) replacement. In 1985, Beyer[25] reported the preparation of high-silica Y-zeolite and even pure-silica Y-zeolite through interaction of SiCLt with NaY for dealumination and Si-addition. This technique is based on the fact that at high temperatures SiCl4 can easily react with zeolites to dealuminate, and the main reaction is given by Equation (6.27). 

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