Harnessing Defect‐Engineered Zr‐MOF Catalyst With Tailored Active Sites For Selective Carboxymethylation of Furfuryl Alcohol

We selectively synthesized a less explored furan‐2‐ylmethylmethyl carbonate (FMMC), a potential green solvent and fuel additive via carboxymethylation of furfuryl alcohol with dimethyl carbonate. A defect‐engineered UiO‐66 MOF catalyst was employed for this transformation, and its activity was benchmarked against conventional catalysts such as H‐ZSM‐5, H‐Beta, and Amberlyst‐15. The nature of the active sites instrumental in obtaining high FMMC selectivity was emphasized by the variation in turnover numbers. The in situ approach of tailoring missing linker defects in the UiO‐66 MOF was achieved with monocarboxylic acid modulators, formic acid and acetic acid. The catalysts were comprehensively characterized for the structural properties by PXRD, N 2 sorption, and FESEM, and the intrinsic active sites were investigated with techniques such as EPR, FTIR, TGA, and acid–base titrations. The defective UiO‐66 MOF demonstrated superior catalytic activity owing to the presence of a higher number of weak Brönsted acidic sites. The selective masking of Brönsted and Lewis acidic sites were studied by treating it with 2,6‐lutidine and KSCN respectively and their effect on the catalytic activity was examined. A Central Composite Design (CCD) model was designed to obtain the high FMMC yield under optimized conditions. The catalyst gave 87.3% furfuryl alcohol conversion and 95.2% FMMC selectivity. The leaching and recyclability experiments showed that the catalyst was truly heterogeneous, and it was recyclable up to five consecutive cycles. The spent catalyst was thoroughly characterized to understand the stability and structural and intrinsic properties.