The Synthesis of SAPO-34 at Different Crystallization Temperature and its Catalytic Performance for Methanol to Olefins Reaction
Volume 11, Issue 4, Autumn 2014, Pages 31-39
H. Nemati Arbatani, J. Towfighi Daryan, F. Kalantar Kohdami
Abstract In order to enhance the catalytic performance of SAPO-34 for the reaction of methanol to light olefins (MTO), three different crystallization temperatures were used to synthesize SAPO-34. The catalysts were synthesized hydrothermally with molar composition as 1 Al2O3: 1 P2O5: 0.4 SiO2: 1 TEAOH: 0.5 TEA: 0.5 MOR: 70 H2O. The effects of the crystallization temperature on the phase purity, morphology and functional groups of SAPO-34 were characterized by XRD, SEM and FTIR techniques. The relative crystallinity was decreased by increasing crystallization temperature and
some impurities appeared at high crystallization temperature. All samples showed cubic morphology with different crystal size. The catalytic performance of synthesized SAPO-34 was investigated in a fixed-bed reactor at 410
C. For the MTO reaction, all synthesized catalysts showed similar product distribution and methanol conversion, but light olefins selectivity was greatly dependent on the crystallization condition. The sample was synthesized at 170 C and 24 h, possessed the highest light olefins due to highest amount of acid sites, relative crystallinity and smallest mean crystal size.
Effect of Crystallization Temperature on the Synthesis of SAPO-34 and its Catalytic Performance in MTO Reaction
Volume 11, Issue 3, Summer 2014, Pages 16-25
F. Kalantar Kohdami, J. Towfighi Daryan, H. Nemati Arbatani
Abstract The effect of different crystallization temperatures on the crystallinity, morphology, surface area and catalytic performance of SAPO-34 has been investigated. SAPO-34 catalysts were successfully synthesized using the conventional hydrothermal method. The prepared samples were characterized by XRD, SEM, BET and FTIR techniques. The catalytic performance of the synthesized catalysts was tested in MTO reaction at 410˚C and WHSV of 6.5 h-1. Temperature of crystallization was found to be the significant parameter for controlling crystallinity and purity, particle size, morphology,
surface area and content of hydroxyl groups of the product. The sample prepared at 463 K and 24h possessed the best crystallinity with the smallest crystal size. In the methanol conversion to olefins over SAPO-34 catalysts, this sample showed highest yield of light olefins (88% wt).