Enhancing the Performance of SAPO-۳۴ Catalyst via Customized Structure-directing Agents: Polyethylene Glycol and Morpholine

SAPO-۳۴, renowned for its exceptional catalytic activity and shape-selective structure, shows great promise as a catalyst for the methanol-to-olefin (MTO) reaction [۱]. Nevertheless, the limited operational lifetime of the SAPO-۳۴ catalyst in MTO applications, primarily attributed to rapid deactivation by coke accumulation, has hindered its well-known industrial utilization [۲]. Extending the durability of SAPO-۳۴ can be achieved by increasing the external surface area of the catalyst and enhancing its hierarchical structure to promote mass transfer efficiency and reduce diffusion limitations [۲]. In this study, we successfully synthesized a hierarchical and cost-effective SAPO-۳۴ catalyst using the hydrothermal method, employing polyethylene glycol ۴۰۰۰ (PEG-۴۰۰۰) as a structure-directing agent along the economically sustainable template morpholine. The synthesis procedure required meticulous mixing of aluminum isopropoxide, tetraethylorthosilicate (TEOS), phosphoric acid, water, morpholine, and PEG-۴۰۰۰ under specific temperature conditions. Comprehensive characterization of the synthesized samples was conducted through X-ray diffraction (XRD), scanning electron microscopy (SEM), and nitrogen adsorption-desorption measurements. XRD analysis revealed that the SAPO-۳۴ sample synthesized with PEG-۴۰۰۰ exhibited a remarkable crystallinity of ۹۱%, compared to the parent sample. Furthermore, the incorporation of PEG-۴۰۰۰ facilitated an enhancement in the hierarchical structure of the catalyst, resulting in a substantial increase in the t-plot external surface area from ۵۳ m۲/g for the conventional sample to ۱۲۰ m۲/g for the PEG-۴۰۰۰ synthesized sample. This expanded surface area plays a vital role in extending the catalyst's operational lifetime. These findings underscore the unique structural properties of the synthesized SAPO-۳۴ catalyst. Overall, our results suggest that the introduction of PEG-۴۰۰۰ and morpholine into the initial gel matrix facilitates the formation of a cost-effective and hierarchical SAPO-۳۴ catalyst, showcasing its potential for efficient catalysis in MTO reactions.

کلیدواژه ها:

Sapo-۳۴ ، MTO ، Hierarchical ، PEG-۴۰۰۰