Synthesis and Physicochemical Characterization of Nanostructured ZrAPSO-34 Molecular Sieve with Various Zr-Content Used in Catalytic Conversion of Methanol to Light Olefins

Conversion of methanol to light olefins (MTO) is one of the most important processes to produce value-added petrochemical material such as ethylene and propylene. In the recent years, importance of MTO process has been increased. It can be due to the increase in the demand for ethylene and propylene and also foreseeable shortage of crude oil. Nanostructured SAPO-34 catalyst seems to be one of the best catalysts in MTO process in terms of selectivity and conversion. In this work, hydrothermal synthesis of ZrAPSO-34 molecular sieve with different concentration of zirconium was investigated. It should be noted that the addition of Zr was carried out by isomorphous substitution into the crystalline framework of SAPO-34. The nanostructured catalysts were characterized byh XRD, FESEM and FTIR analyses. Nanostructured ZrAPSO-34 catalysts were evaluated in a fixed-bed reactor at temperature range of 300-500ºC to determine the effect of temperature in the MTO process. Presence of zirconium in the initial gel can influence the Si substitution mechanism in CHA structure of SAPO-34 and consequently change acidity and catalytic property. Incorporation of zirconium changed crystal and particle size significantly observed from XRD and FESEM results, respectively. XRD analysis reveals that crystallinity of the samples decreased as a result of Zr introduction. Zirconium incorporation into SAPO-34 structure improved olefins production and decreases methane formation especially at high temperatures. Concentration of zirconium has considerable effect on physicochemical properties and also catalytic performance of nanostructured catalyst in methanol to olefins conversion. Nanostructured ZrAPSO-34 catalyst show promising stability in the MTO process

Keywords:

ZrAPSO-34 , Zirconium content , Hydrothermal Synthesis , Methanol to Olefins Process