THE EFFECAT OF SILICA MODULE ON THE PROPERTIES OF HZSM-5 ZEOLITE IN THE CONVERSION OF METHANOL INTO HYDROCARBONS

Abstract

In a flow-through unit with stationary bed catalyst (4cm3) HZSM-5 with silica modules 61 and 200 the activity and stability of operation in the process of methanol conversion were studied. It was found that the activity and selectivity of zeolite catalyst is determined by the value of silica module and concentration of strong Bronsted acid sites of zeolite. Increasing the silicate modulus from 61 to 200 leads to a significant increase in the operating time of HZSM-5 zeolite. On HZSM-5 with silica module 61, which has a significant concentration of strong Bronsted acid sites (528 μmol/g-1), a gradual decrease in its activity occurs with increasing duration of operation, and after 10 hours of operation it loses 90% of its initial activity. HZSM-5 with silica module 200, which has a low concentration of strong Bronsted acid sites (321 μmol/g-1) shows higher stability and does not lose its initial activity during 22 hours of operation. The high stability of HZSM-5 zeolite with silica module equal to 200 is due to the fact that due to the low concentration of strong Bronsted acid sites in the process of methanol conversion its pores are not blocked by coke deposits.