CuCo双金属催化剂催化糠醛加氢制备1,5-戊二醇的研究

Hydrogenation of furfural to 1,5-pentanediol over CuCo bimetallic catalysts

  • 摘要: 通过尿素均匀沉淀法合成了一系列具有不同Cu/Co物质的量比的CuxCo3–xAl类水滑石催化剂,并将其用于糠醛(FAL)直接加氢-氢解制备1,5-戊二醇(1,5-PeD)。研究结果表明,Cu/Co物质的量比对催化剂的织构性质及其催化性能具有显著的影响。当Cu/Co物质的量比为1∶29(Cu0.1Co2.9Al)时,催化剂表现出优异的催化性能,在140 ℃,4 MPa H2条件下反应6 h,糠醛的转化率为100%,戊二醇的收率为51.1%,其中,1,5-戊二醇的收率为41.1%。采用程序升温还原(H2-TPR)、程序升温脱附(H2-TPD)、X射线光电子能谱(XPS)和拉曼光谱(Raman)等表征技术证实,Cu0.1Co2.9Al催化剂具有高活性的原因在于其表面具有最高含量的Cu0和CoOx,且两者具有协同催化效应。Cu0用于吸附和活化H2,CoOx具有一定氧空位,可以促进糠醛分子中C=O基的吸附与活化,使其快速加氢生成糠醇,同时氧空位可以锚定中间体糠醇中–OH使其在催化剂表面产生C2端斜式吸附,促使C2=C3加氢,弱化C2–O1键使其断裂,进而提高1,5-戊二醇的选择性。

     

    Abstract: A series of CuxCo3xAl hydrotalcite-like catalysts with different Cu/Co molar ratios were synthesized by the urea homogeneous precipitation method and used for the direct hydrogenation–hydrogenolysis of furfural to 1,5-pentanediol. The results showed that the Cu/Co molar ratio of the catalyst had a significant effect on its textural properties and catalytic performance. The catalyst exhibited excellent catalytic performance when the molar ratio of Cu/Co was 1∶29 (Cu0.1Co2.9Al), and the conversion of furfural was 100% together with 51.1% yield of pentanediol among which the yield of 1,5-pentanediol was 41.1%, under the reaction condition of 140oC, 4 MPa H2 for 6 h. Extensive characterization techniques, including temperature-programmed reduction (H2-TPR), temperature-programmed desorption (H2-TPD), X-Ray photoelectron spectroscopy (XPS) and Raman confirmed that the excellent catalytic activity of Cu0.1Co2.9Al catalyst was attributed to the highest content of Cu0 and CoOx on its surface, and a synergistic catalytic effect was present between them. Typically, Cu0 was used to adsorb and activate H2, and CoOx with much oxygen vacancies promoted the adsorption and activation of C=O groups in furfural molecules, leading to the quick conversion of furfural to furfuryl alcohol. In addition, the oxygen vacancies anchored the –OH in the intermediate furfuryl alcohol to produce a C2-terminal oblique adsorption on the catalyst surface. Then it promoted the hydrogenation of C2=C3 with the weakening and cleavage of C2–O1 bond, and enhanced the selectivity of 1,5-pentanediol.

     

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