Cs/B催化剂载体对甲苯甲醇侧链烷基化性能的影响

The Effect of Different Carrier Supported Cs and B Catalysts on Catalytic Performances for Side-chain Alkylation of Toluene and Methanol

以间苯二酚、甲醛为碳源合成的有序介孔碳(OMC)为载体,采用浸渍法制备了含Cs和B的负载型催化剂(CsB/OMC)。对其与不同载体改性催化剂的甲醇甲苯侧链烷基化性能进行了对比研究。采用XRD、CO2-TPD、NH3-TPD、氮吸附-脱附、TEM等手段对催化剂进行了表征。实验结果发现,不同载体催化剂的甲苯甲醇侧链烷基化活性顺序由大到小依次为:CsB/OMC,CsB/MCM-41,CsB/AC,CsB/ZSM-5.其中,CsB/OMC活性最高,乙苯和苯乙烯的总收率可达到34.9%;CsB/MCM-41中苯乙烯的选择性较高。研究表明,弱碱中心有利于提高侧链烷基化活性,弱酸中心和中强碱中心的协同作用有利于提高苯乙烯的选择性。

Ordered mesoporous carbon supported Cs and B catalysts （CsB/OMC） were pre-pared by impregnation of Cs and B components on OMC carrier, which was synthesized by a two- step method of soft template using resorcinol and formaldehyde as carbon precursor,triblock co- polymer Pluronic F127 as template. The catalytic performances were investigated and compared for side chain alkylation of toluene with methanol over the different carriers modified catalysts. The catalysts were characterized by X-ray diffraction （XRD）,nitrogen adsorption-desorption iso-therm, transmission electron microscopy （TEM）, temperature programmed desorption of CO2（CO2-TPD） and temperature programmed desorption of NHa （NHa-TPD）. The catalytic performances and characterization results of different carriers modified catalysts were compared. It reveals that catalytic activity of side chain alkylation decreases in the order CsB/OMC, CsB/MCM-41, CsB/AC,CsB/ZSM-5, and the yield of ethylbenzene and styrene （Ysty＋ЕВ） reaches 34.9% over the CsB/OMC. The weak base sites can help improve the side chain alkylation catalytic activity, and the high styrene selectivity requires coordination of appropriate weak acid and weak-medium base sites.