无定形硅铝改性TiO_(2)负载Ru催化加氢解聚二苯醚的研究

Catalytic hydrogenolysis of diphenyl ether over Ru supported on amorphous silicon-aluminum-TiO_(2)

采用蒸汽辅助法合成了无定形硅铝(ASA)-TiO_(2)复合载体,并在此基础上制备了双功能催化剂Ru_(5)/ASA-TiO_(2)。利用X-射线衍射(XRD)、吡啶吸附红外(Py-FTIR)、氨-程序升温脱附(NH3-TPD)、扫描电子显微镜(SEM)、透射电子显微镜(TEM)和X射线光电子能谱(XPS)等手段对所制备催化剂的结构和酸性进行了详细表征。以二苯醚为褐煤模型化合物,在温和条件下考察了催化剂Ru_(5)/ASA-TiO_(2)加氢解聚4–O–5类型醚键的反应活性,二苯醚的转化率高于98%,苯收率为67.1%。弱Brønsted酸和/或Lewis酸而非强Brønsted酸是提高二苯醚的加氢解聚转化率和苯收率的主要因素,并且反应温度能够影响各类型酸的相对含量从而显著影响二苯醚加氢解聚产物的选择性。

A bifunctional catalyst of Ru_(5)/ASA-TiO_(2) was prepared by using a novel silicon-aluminum(ASA)-TiO_(2) amorphous composite,which was synthesized by a steam-assisted method,as the support.X-ray diffraction(XRD),pyridine adsorption infrared(Py-FTIR),ammonia-temperature-programmed desorption(NH_(3)-TPD),scanning electron microscopy(SEM),transmission electron microscopy(TEM),X-ray photoelectron spectroscopy(XPS)and other methods were used to characterize the structure and the acidity of the prepared catalyst.Using diphenyl ether as the lignite-related model compound,the reaction activity of the Ru_(5)/ASA-TiO_(2)for the catalytic hydrogenolysis of 4–O–5 type ether bonds was investigated under a mild condition.The results show that the weak acid and/or the Lewis acid rather than the strong Brønsted acid mainly contribute to improve the conversion rate and the benzene yield of the catalytic hydrogenolysis of diphenyl ether.The reaction temperature can influence the relative content of various types of acids to significantly affect the selectivity of the hydrogenolysis products of diphenyl ether.The conversion rate of diphenyl ether is greater than 98%while the benzene yield is 67.1%.