Solvent-free synthesis of MFI-type zeolites and their degradation properties of gas-phase styrene

Abstract

In this study, a series of MFI-type zeolites with various compositions were synthesized by a solvent-free synthesis method at a comparatively mild condition. The results of investigations showed that the as-synthesized samples displayed a good crystallinity grade and regular morphology of layered structure. The crystallization process of TS-1 was systematic investigated. It was revealed that the transition stage of crystallization process was the formation of nucleation intermediates (Na2SiF6), which was the key factor for dropping Ti atoms into MFI framework. Meanwhile, it showed a high apparent nucleation activation energy (64.8 kJ mol−1), and low growth activation energy (25.3 kJ mol−1) in a spontaneous nucleation system, and the nucleation activation energy could be reduced to 17.2 kJ mol−1 in non-spontaneous nucleation system. The as-synthesized zeolites were evaluated for their catalytic activity for the degradation of gas-phase styrene. The titanium silicalite-1 sample doped with iron exhibited excellent catalytic activity with 100% degradation of styrene. The method employed in this work not only decreases the production cost and energy-consumption of MFI-type zeolites, but also significantly enhances their production yield. Moreover, it is an efficient pathway to solve the pollution of volatile organic compounds using solid waste.