磷改性Cr2O3/Al2O3催化4-乙基酚转化制轻质芳烃

以烷基酚转化为轻质芳烃（苯和甲苯）为目标，制备了Cr₂O₃/Al₂O₃催化剂，并以4-乙基酚为模型化合物研究了其加氢反应性能。体积空速、氢油比、反应压力和温度升高时，脱烷基率、芳烃总选择性、轻质芳烃选择性呈先增大后减小的趋势，反应温度对转化率影响较大。以不同浓度磷酸对Cr₂O₃/Al₂O₃进行改性，随着磷酸用量的增大，催化剂酸量总体增大，主要是弱酸和中强酸，酸强度先增加后降低，磷酸用量较高时，弱酸增加幅度较大。与未改性相比，质量分数8%磷酸改性Cr₂O₃/Al₂O₃上4-乙基酚转化率99.5%，脱烷基率提升9.4%，达74.4%，轻质芳烃选择性提高4.0%，达到57.0%，以较高选择性实现了转化制轻质芳烃，同时，芳烃总选择性高达80.4%，较高程度保持了芳环不被破坏。提出了Cr₂O₃/Al₂O₃上4-乙基酚加氢反应的路径并对反应机理进行了研究。

Conversion of 4-ethylphenol to light aromatics on the Cr2O3/Al2O3 modified by phosphoric acid

With the goal of conversion of alkylphenols to light aromatics (benzene and toluene), Cr₂O₃/Al₂O₃ catalysts were prepared and their hydrogenation performance was investigated using 4-ethylphenol as a model compound. With the increase of LHSV, H₂/oil, reaction pressure and temperature, the dealkylation rate, the total selectivity of aromatics, and the selectivity of light aromatics first rose and then dropped. The conversion of 4-ethylphenol was obviously influenced by the reaction temperature. Cr₂O₃/Al₂O₃ was modified with different concentrations of phosphoric acid. As the increase of the amount of phosphoric acid, the general amount of weak and medium acids on the catalyst increased, and the strength of acid was first enhanced and then weakened. The amount of weak acid increased significantly under a high value of the amount of phosphoric acid. Compared with the unmodified catalyst, the conversion of 4-ethylphenol on the catalysts modified by 8% phosphoric acid is higher than 99.5%, while the dealkylation rate of 4-ethylphenol increased by 9.4%, reaching to 74.4%, and the selectivity to light aromatics (benzene and toluene) increased by 4.0%, reaching to 57.0%. Conversion of 4-ethylphenol to light aromatics was achieved in high selectivity. Furthermore, the total selectivity of aromatics was as high as 80.4%, which meant that most of the aromatic rings was not broken. The path of hydrogenation reaction of 4-ethylphenol on Cr₂O₃/Al₂O₃ was proposed and the reaction mechanism was discussed.