An ecofriendly and reusable solid acid catalyst ZrO₂‐SIEC for highly selective alkylation of 2,4/2,5‐xylenol

Abstract

Monodisperse composite microspheres were prepared of zirconia and urea formaldehyde resin having an average particle size of 2.2 μm. Their surface was modified by silane coupling agent and styrene, and then sulfuric acid assisted with silver sulfate to form solid sulfonic acid based ion‐exchange catalyst (namely, ZrO2‐SIEC) for the alkylation of 2,4/2,5‐xylenol mixture. The selectivities of catalyst ZrO2‐SIEC to produce 6‐2,4‐xylenol and 4‐2,5‐xylenol were found to be 98.9% and 97.9%, with yields of 98.6% and 80.9%, respectively. The optimized reaction conditions were identified including temperature (80°C), catalyst dosage (9%) and reaction time (180 min). In addition, catalyst ZrO2‐SIEC showed good reusability for maintaining stable catalytic performance over 25 cycles of reuse, attributed to its stable mechanical, thermal and chemical properties. Comparison with other four catalysts demonstrated good performance of ZrO2‐SIEC in terms of catalytic activity, operating conditions, separation from products, and environmental friendliness.