Synthesis of SAPO-34 nanocrystallites by epoxy-functional organosilane with improved MTO catalytic performance

Abstract

Synergic regulation of microstructure, morphology and acidity of SAPO-34 molecular sieve is crucial to enhance its catalytic performance for methanol to olefins (MTO) reaction. Herein, a commercial oxygen-containing organosilane 3-glycidoxypropyltrimethoxysilane (AC-230) was developed as a new mesoporogen to synthesize pure SAPO-34 nanocrystallites together with diisopropylamine and seeds. According to the conditional experiments and systematic characterizations, it was disclosed that AC-230 not only changed the morphology and particle size of the SAPO-34 crystals but also affected its compositions and acidic properties. The addition of seed was indispensable to fasten the crystallization rate and hence assure the crystal growth inhibition function of AC-230. Thanks to the formed shortened diffusion pathway, moderate acid sites and pure CHA structure of the nanosized SAPO-34 product, the catalyst demonstrates excellent catalytic performance with a longer lifetime (395 min) and higher ethylene plus propylene selectivity (82.88%) in comparison to its conventional analogs (259 min and 80.63%).