The ways of improving the catalytic action stability of MFI zeolites and increasing the lifetime of the catalysts based on MFI zeolites

Abstract

The increasing the stability of the MFI type zeolite catalysts is actual for creating of high active catalysts for methanol conversion to C2–C4 hydrocarbon gases or hydrocarbons to aromatics – an important industrial processes. Three new approach to improve the stability of zeolite catalysts are proposed in the work: the selective dealumination on the outer surface of the MFI zeolite crystals; the structure-selective ion exchange on the external surface of the crystals, the use of isothermal (tubular) reactor. The influence of conditions of selective dealumination and structurally selective ion exchange on the molar ratio SiO2/Al2O3 of the zeolite and time between regeneration running in the conversion of methanol into hydrocarbons is studied. It is found that the selective dealumination of external surface leads to an increase of between regeneration running up to 3–5 times. Structure-selective ion exchange on the outer surface of the zeolite crystals can increase the time of running in 2–4 times, reduce the temperature and duration of recovery due to changes in the properties of the deposited coke. Application of the tubular reactor allows to facilitate the regeneration process compared with an adiabatic reactor by the formation of less condensed coke.