Catalytic alkylation of Phenol and Methanol to 2,6-Xylenol using Iron Oxides synthesized via thermal decomposition of Iron precursors

Iron oxides are considered ideal catalysts for the ortho C-alkylation of phenol and methanol due to their favorable properties, so the simple synthesis of high-performance iron oxides will be of great significance. Different iron oxides catalysts are synthesized by direct thermal decomposition of five different iron precursors, and the effects of calcination temperature and atmosphere on their catalytic performance are analyzed. Characterization and experiments indicate that the total acidic content in the catalyst show a good correlation with its catalytic performance. The catalyst synthesized from iron citrate, with a high total acidic content, exhibits the best catalytic performance. The effects of reaction conditions are investigated. With the temperature increases, the conversion of phenol and the selectivity of 2,6-xylenol both show a “volcanic” trend. Unlike most previous reports, the molar ratio is positively correlated with catalytic performance, and the competitive adsorption of phenol and methanol is virtually negligible on the catalyst. Under the optimized reaction conditions, the conversion of phenol can achieve 99.4 % with a selectivity of 93.7 % to 2,6-xylenol. Finally, the causes of catalyst deactivation are analyzed and explained. The catalyst exhibits competitive catalytic performance and provides a novel approach for the efficient methylation of phenol.