Meeting Specifications of SAPO-34 Molecular Sieve with Multi-templates for MTO Reaction: Kinetic and Experimental Study

Light olefins become are important products for polymeric and petrochemical industries. Producing olefins from oil become ineffective due to highly production cost. An alternative method for producing olefins using methanol instead of oil source become an efficient process. SAPO-34 considered as a proper zeolite catalyst used in this field. For this purpose, there were many attempts to prepare it with microwave irradiation using DEA, TEA and MOR as templates. Fixed power of 800 W for 200 min was applied in crystallization step. XRD, BET, SEM, EDX, FTIR and TGA analysis were studied for preparing catalysts. XRD analysis showed that producing SAPO-34 using DEA and TEA failed and instead of it, SAPO-41 appeared. SAPO-34 was successfully prepared using MOR template. The surface area was 123.10, 226.42 and 194.63 m2/g using SP/DEA, SP/TEA and SP/MOR, respectively. SEM-EDX analysis showed large particles of SP/DEA and SP/TEA with relatively small particles of SP/MOR. FTIR peaks of SP/MOR were identical with SAPO-34 spectra peaks. TGA analysis revealed very high stability at high temperature. MTO kinetic results showed that the reaction obeys the first-order with activation energy of 17.383 kJ/mol. MTO conversion process was performed in fixed bed reactor with different temperatures at 350, 400, 450 and 500 oC and weight hourly space velocities at 7.7, 15 and 21.1 h–1. Temperature of 400 oC recorded higher olefins selectivity at about 63% of total products and 100% conversion for 400 min. It was found that increasing temperature and WHSV cause decreasing of conversion and olefins selectivity.