Precise control of the size of zeolite B-ZSM-5 based on seed surface crystallization

Abstract

A series of boron-containing ZSM-5 (B-ZSM-5) catalysts with particle sizes from ∼153 nm to ∼14.2 μm are synthesized by regulating the addition of silicalite-1 seeds. The B-ZSM-5 particle size with seed addition (D), the seed addition amount (x), the seed particle size (d) and the B-ZSM-5 particle size without seed addition (D₀) are related with by the new function D³ = d³D₀³/[xD₀³ + (1 − x)d³], and the particle size of B-ZSM-5 has been precisely controlled and predicted in both micro (TPABr as template) and nano (TPAOH as template) synthesis systems. The function also shows the evolution of B-ZSM-5 particle size versus the seed amount and size, which helps guide the synthetic choice of the seed amount used or decreasing the seed size to decrease the B-ZSM-5 size for a specific synthesis system. Furthermore, the effect of particle size on the catalytic performance of B-ZSM-5 for the methanol to propylene (MTP) reaction is also investigated. The addition of 1 wt% ∼74 nm seeds to the synthesis system improves the resulting catalyst lifetime from 46 h to 794 h.