SAPO-34 is highly selective and hydrothermally stable for MTO reactions but it is rapidly deactivated by the formation of coke through its micropores. The promising SAPO-34/ZSM-5 nanocomposite catalyst with a different ratio was synthesized by the ultrasonic-assisted hydrothermal method and it obtained products that were characterized to further investigate their catalytic performance. Utilization of the ultrasound method led to a faster synthesis time, a decrease of crystallite size, an increase of surface area, and a dominant mesopore structure. The physicochemical properties of the product were extensively investigated by XRD, FESEM, TEM, FT-IR, N2 adsorption–desorption techniques, and NH3-TPD. Results indicate that the composite had high conversion and selectivity compared to that of the original ZSM-5 and SAPO-34. When composite structures due to the synergic effect between ZSM-5 and SAPO-34 acted as promoted catalysts, they improved catalytic properties of composite catalysts. Moreover, the SAPO-34/ZSM-5 nanocomposite catalyst with 50% ratio synthesized by the ultrasonic-assisted hydrothermal method (U–S/Z (50%)) showed 100% conversion and 90% selectivity to light olefin at 450 °C.

SAPO-34 as a catalyst has high selectivity and hydrothermal stability, but it is rapidly deactivated by the formation of coke in its micropores. Evaluating the natural Clinoptilolite capability as a binder in nanocomposite catalysts is of interest because of its low cost, and accelerating the reaction. The SAPO-34/Clinoptilolite (S/C) nanocomposite catalysts were synthesized via ultrasonic-assisted hydrothermal method using Clinoptilolite as a binder. Subsequent performance of the catalyst was investigated in the methanol to olefins (MTO) reaction. The structures of synthesized nanocomposite were characterized with several methods such as XRD, XRF, FESEM, TEM, NH 3-TPD, FT-IR, and nitrogen adsorption techniques. The modified Clinoptilolite was attained using nitric acid treatment. Although the physicochemical analysis indicated that HNO 3-treatment decreases the crystallinity of the Clinoptilolite, the specific surface area of natural zeolite enhances considerably from 20.07 to 187.8 m 2 /g. The nanocomposite catalysts showed high selectivity toward light olefins with 100% conversion and 90% selectivity to light olefins as desired products at 450˚C. Nanocomposite with the additional diffusion paths for mass transfer provided by binder-filled space ascend to higher catalytic lifetimes in compare with free SAPO-34 catalyst.

Aim and Objective: The research focuses on recent progress in the production of light olefins. Hence, the common catalyst of the reaction (SAPO-34) deactivates quickly because of coke formation, we reorganized the mechanism combining SAPO-34 with a natural zeolite in order to delay the deactivation time. Materials and Methods: The synthesis of nanocomposite catalyst was conducted hydrothermally using experimental design. Firstly, Clinoptilolite was modified using nitric acid in order to achieve nano scaled material. Then, the initial gel of the SAPO-34 was prepared using DEA, aluminum isopropoxide, phosphoric acid and TEOS as the organic template, sources of Aluminum, Phosphor, and Silicate, respectively. Finally, the modified zeolite was combined with SAPO-34's gel. Results: 20 different catalysts due to D-Optimal design were synthesized and the nanocomposite with 50 weight percent of SAPO-34, 4 hours Crystallization and early Clinoptilolite precipitation showed the highest relative crystallinity, partly high BET surface area and hierarchical structure. Conclusion: Different analysis illustrated the existence of both components. The most important property alteration of nanocomposite was the increment of pore mean diameters and reduction in pore volumes in comparison with free SAPO-34. Due to low price of Clinoptilolite, the new catalyst develops the economy of the process. Using this composite, according to formation of multi-sized pores located hierarchically on the surface of the catalyst and increased surface area, significant amounts of Ethylene and Propylene, in comparison with free SAPO-34, were produced, as well as deactivation time that was improved.