Synthesis and catalytic application of ZSM-48 zeolite

Abstract

ZSM-48 is a kind of high-silica zeolite with one dimensional (1D) 10-member ring (10-MR) channel structure. It is well known for its unique pore structure and acid properties, as well as exceptional catalytic performance in various reactions. However, the diffusion limitation and insufficient acid density pose significant challenges to its widespread application and promotion. This review aims to summarize the advancements in enhancing diffusivity and regulating acid properties of ZSM-48 zeolite, as well as its catalytic applications. To alleviate diffusion limitations, the construction of hierarchical ZSM-48 zeolites through post-treatment and in situ strategies is extensively summarized. Ongoing endeavors focus on determining the optimal balance between maintaining structural integrity and improving mass transfer capacity through post-treatment techniques. Concerning acid regulation, various strategies such as the use of a special organic structure directing agent (OSDA), seed-assisted synthesis, zeolite hybridization, and heteroatom doping strategies have been developed. The emphasis on acid regulation in ZSM-48 zeolite involves efforts to design or discover more cost-effective OSDAs. Additionally, researchers are exploring simpler and more economical seed-assisted synthesis routes to produce Al-rich candidates. In terms of catalytic application, extensive research has been conducted on various reactions including hydroisomerization of paraffin, isomerization of xylenes, cracking of hydrocarbons, and methanol conversion to hydrocarbons. Its distinctive catalytic performance is primarily related to the shape-selective advantage conferred by its 1D channel structure. In particular, ZSM-48 zeolite is widely regarded as the leading candidate in paraffin hydroisomerization reactions, attributed to its high proportion of multi-branched isomers in the catalytic products. The present review aims to provide a comprehensive reference for researchers dedicated to the synthesis, modification, and application of ZSM-48 zeolite.