A comprehensive review on sustainability-motivated applications of SAPO-34 molecular sieve

Silicoaluminophosphate-34 (SAPO-34) is a molecular sieve with a unique shape structure and pore framework, favorable acidic properties, and excellent stability under different operating conditions. These unique properties have made SAPO-34 an important material with widespread applications as a catalyst, membrane, and adsorbent in different processes. As a catalyst, SAPO-34 is utilized in converting methanol to olefins (MTO) with outstanding catalytic performance, excellent selectivity, and stability. The only drawback of this molecular sieve is its rapid deactivation in the reaction environment, which hinders its application at large scales. To overcome this drawback, reducing the particle size and tailoring the hierarchal structure have been proposed as two key strategies. As a membrane, SAPO-34 can be exploited in severe conditions (i.e., high temperature and pressure), for example, to separate hydrogen, methane, and carbon dioxide in a membrane reactor, where polymeric membranes cannot be used. In this case, the membrane fabrication method plays a vital role in determining the final performance. With a focus on these applications, this review discusses the preparation of SAPO-34 and its applications as a catalyst in the MTO reaction and as a membrane in gas separation. Key strategies to improve its properties and performance are elaborated. Lastly, complementary applications of this molecular sieve are briefly discussed. This review may provide helpful insights for the development of high-performance SAPO-34-based materials to be applied in different industries.