Tandem Maneuvering of Acidic Sites and Porosity of Zeolite Beta Catalyst for Enhanced C–C Benzylation of Lignin Model 4‐Ethylphenol

Zeolite Beta catalysts were explored in the benzylation of lignin-based model 4-ethylphenol to produce 2-benzyl-4-ethylphenol, an important high-density precursor for jet-fuel blending. For optimal catalytic attributes, a combined dealumination-surfactant templating was deployed to obtain Zeolite Beta, with higher Si/Al ratio (∼33-39) and integrated mesoporosity. The extent and quality of mesopores were tuned by varying CTAB quantity (0.01-0.06 M) at a fixed NH₄OH concentration (0.5 M). The enhanced templating action of CTAB micelles at higher CTAB concentrations created uniform intracrystalline mesopores of 3.5 nm. This mesopore generation was predominantly directed by healing of excess SiO^- defects associated with Al vacancies at higher CTAB concentrations as evidenced by silanol speciation study using DRIFTS. Further, ²⁷Al MAS-NMR and DRIFTS (Al-OH) revealed the loss and subsequent recovery patterns of framework Al during the dealumination and surfactant templating process, respectively. Eventually, large mesopores with a higher fraction of reinstated Brønsted acidity were generated in the CTAB-templated Beta catalysts, especially at higher CTAB concentrations (0.03 and 0.06 M). Dealuminated Beta templated with 0.06 M CTAB showed the highest benzyl alcohol conversion (∼29%), the highest selectivity for 2-benzyl-4-ethylphenol (∼42%), and the lowest dibenzyl ether selectivity (∼20%). Improved performance was attributed to its large uniform mesopores, highest Brønsted-to-Lewis acid ratio (B/L) and recovered superstrong acid sites.