Silicoaluminophosphate molecular sieves SAPO-11, SAPO-31 and SAPO-41: Synthesis, characterization and alkylation of toluene with methanol

Abstract

Medium pore molecular sieves SAPO-11, SAPO-31 and SAPO-41 have been synthesized using di-n-propylamine as the organic template. They have been characterized by various methods such as X-ray powder diffraction, solid state MAS NMR spectroscopy, thermal analysis, chemical analysis and temperature programmed desorption (TPD) of ammonia. Catalytic activities of these materials in the alkylation of toluene with methanol have been studied. While SAPO-11 and SAPO-31 showed moderate activity, very high catalytic activity was shown by SAPO-41. All the catalysts showed varying degrees of shape selectivity towards p-xylene. SAPO-41 gave a large amount of 1,2,4-trimethylbenzene in addition to the xylenes.