Quantitatively regulating ZSM-48 by phenolic molecules for n-hexadecane hydroisomerization

ZSM-48 is widely used to support Pt nanoparticles (Pt/ZSM-48) for hydroisomerization of long-chain n -paraffin due to its 10-member-ring one-dimensional pore structure . But the yield of target isomers on Pt/ZSM-48 is difficult to be improved due to easily bundled crystal bars and relatively excessive acid sites of ZSM-48, which restricts reactant diffusion and causes cracking. In this study, different types of zeolite growth modifiers (ZGMs) are screened for regulating the physicochemical property of ZSM-48, in which phenolic hydroxyl was found to be the most effective functional group. Quantitative correlations between ZGM structure and the properties of corresponding ZSM-48 crystal are achieved based on appropriate descriptors and multi-parameter regression. Then, the mechanism of ZSM-48 regulation by phenolic ZGMs is revealed. The models predict that polydopamine (PDA) is a superior ZGM for hydroisomerization, which is verified by textural characterization and reaction evaluation. Compared with the conventional catalyst, the isomer selectivity was improved effectively from 92% to over 97% when the feed conversion was lower than 80%, and the maximum yield of isomers was 89.0% as catalyzed by the PDA-regulated catalyst. The as-built models can also be used to design preferred phenolic ZGMs for preparing tailored ZSM-48 in other applications.