The effects of templating on the catalytic performance of SAPO-34 catalyst have been investigated in conversion of methanol to olefins. SAPO-34 catalysts were synthesized using a different combination of morphine, tetraethyl ammonium hydroxide (TEAOH) and triethylamine (TEA) as structure-directing agents during synthesis of gel with nominal composition as 1Al2O3: 1P2O5: 0.4SiO2: 2yTEAOH: 2xTEA: 2 (1- (x+y)) morpholine: 70H2O.The different SAPO-34 samples were characterized by XRD, SEM, FTIR, BET, EDX and TPD techniques. Increasing TEAOH in synthesis gel led to decreasing mean crystal size. The catalytic performance of the synthesized catalysts was tested in MTO reaction at 410oC and a feed WHSV of 6.5 1/h.The catalyst synthesized by combination of tri-templates exhibited highest light olefins yield in 100% methanol conversion. The optimum values (X=0.17, Y=0.34) were obtained by central composite design and response surface contour plots.

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 410oC 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%).

The SAPO-34 catalyst was synthesized by the combination of TEAOH and morpholine templates, and colloidal silica and silicic acid, as the silica source under hydrothermal conditions. The effect of the template molar ratio and silica source on the physicochemical properties of each catalyst was studied by XRD, SEM, BET and TPD techniques. XRD patterns revealed the significant effect of gel composition on the crystallinity and particle size of the samples. SEM photos showed that all the catalysts have cubic morphology, but their particle size was different. According to the XRD and SEM of the catalyst prepared by silicic acid, this catalyst showed low crystallinity and large crystal size. TPD analysis indicated that the acidity reduced by increasing the morpholine content in the reaction mixture. The catalytic performance of the synthesized catalysts was tested in MTO reaction. The catalyst produced by the TEAOH/morpholine ratio of 0.5:1.5 exhibited the highest light olefins yield, as well as the longest catalyst lifetime. The maximum yield of ethylene and propylene was determined to be 94 wt%, with 100% methanol conversion.

In order to enhance the catalytic performance of SAPO-34 catalyst for the reaction of methanol to olefins (MTO), ultrasonic and microwave-assisted aging method was employed in static hydrothermal method to synthesize nano-sized SAPO-34. The effects of the application of this method on the chemical composition, morphology, surface area and total acidity of SAPO-34 were investigated by XRD, FE-SEM, nitrogen adsorption–desorption and NH3-TPD techniques. The catalytic performance of synthesized SAPO-34 was investigated for MTO reaction in a fixed-bed reactor under the same operating conditions (T=450oC, P=1 atm, and WHSV=4 h-1). Comparing with the SAPO-34 synthesized with conventional hydrothermal method, the sample synthesized with simultaneous use of US and MW-assisted aging methods possessed larger surface area and small crystal size and exhibited higher selectivity to light olefins (C=2-C=4) and longer lifetime.