N-Methylformamide-Assisted Synthesis of Highly Active Nanosheet Vanadium-MFI Zeolite for Efficient Oxidation Desulfurization and Exploration of the Synthesis Mechanism

Vanadium-containing MFI zeolites have attracted increasing attention as heteroatom zeolite catalysts; however, precise regulation of vanadium speciation within the framework remains challenging. Herein, N-methylformamide (NMF) was introduced as an additive to assist the hydrothermal synthesis of vanadium-MFI zeolite enriched with framework-associated V4+ = O(OSi)2(OH) species. The resulting catalyst exhibits high catalytic activity in oxidative desulfurization (ODS), achieving 91.63% conversion of dibenzothiophene (DBT) within 20 min and nearly complete conversion within 45 min, together with a high turnover frequency of 117.1 h–1. Spectroscopic analysis suggests that V4+═O(OSi)2(OH) is a highly active vanadium species for the ODS reaction. By dynamically tracking the evolution of vanadium species during crystallization, the possible role of NMF in regulating vanadium coordination and framework incorporation was elucidated. The results reveal that both NMF concentration and crystallization time are critical parameters governing the formation of V4+═O(OSi)2(OH). Comparative studies using different amide additives, combined with catalytic performance and density functional theory calculations, further support that the coordination ability of amides toward V4+═O determines vanadium speciation and catalytic activity. This work provides mechanistic insight into amide-assisted regulation of heteroatom environments in zeolite frameworks and offers a rational strategy for designing highly active oxidation desulfurization catalysts.