低负载量Ru-W-B/NaY催化剂制备及其对对苯二酚加氢性能

Preparation of Low-loading Ru-W-B/NaY Catalysts and Their Catalytic Performance for Hydrogenation of Hydroquinone

通过浸渍-化学还原法制备出一系列低负载量的钌基催化剂,在Ru-B二元催化体系中加入少量W,催化性能显著提高。采用XPS、H2-TPD、XRD、SEM、ICP-OES对催化剂物相结构、组成、形貌进行表征,发现采用反加法、添加W、超声波辅助、使用聚乙二醇(PEG)对载体NaY进行涂覆制备的催化剂活性金属粒子分散更均匀,活性位数量更多。以对苯二酚加氢制1,4-环己二醇为探针反应对所制备的催化剂进行活性测试,发现Ru-W-B/NaY-IUP(1500)0.6〔I代表反加法,U代表在制备过程中使用超声波,P代表制备过程中使用了PEG,1500为PEG相对分子质量,0.6为PEG用量(0.6 g)〕加氢性能最为优越,对苯二酚转化率为99.7%,1,4-环己二醇选择性为92.3%,而钌的负载量(以钌在催化剂中所占质量分数计,下同)仅为0.45%。此外,研究了反应液pH对加氢反应的影响,发现反应液pH对反应影响大,当反应液呈碱性时,反应速率得到提高。

A series of low-loading ruthenium-based catalysts were prepared by impregnation-chemical reduction method. The introduction of a small amount of W into the Ru-B binary catalyst system improved the catalytic performance of the catalyst. The structure, composition and surface morphology of the catalysts were characterized by XPS, H2-TPD, XRD, SEM and ICP-OES. It was found that the active metal particles of the catalyst prepared by inverse addition, W addition, ultrasonic assisted technique, and carrier NaY coated by PEG were dispersed more evenly and the number of active sites was more. The activity of the catalyst was tested via hydrogenation of hydroquinone to 1,4-cyclohexanediol. The results showed that Ru-W-B/NaY-IUP(1500)0.6(I means reverse addition, U means ultrasound used in the preparation process,P means PEG used in the preparation process, 1500 means relative molecular mass of PEG, and 0.6 means PEG dosage, 0.6 g) exhibited the best hydrogenation performance. The conversion of hydroquinone was99.7%, the selectivity of 1,4-cyclohexanediol was 92.3%, and the ruthenium loading was only 0.45%(mass fraction of ruthenium in a catalyst, the same below). In addition, the effect of pH value of the reaction solution on the hydrogenation of hydroquinone was studied. The results revealed that the pH value of the reaction solution had a great influence on the reaction. When the reaction solution was alkaline, the reaction rate was greatly accelerated.