Abstract:

The Pt-Ni bimetallic catalyst supported on the graded pore ZSM-5 zeolite was prepared by the equal volume co-impregnation method, and the effect of different Pt/Ni ratios on hydrodeoxygenation performance of guaiacol and dibenzofuran was systematically studied. The physicochemical properties of the as-synthesized Pt-Ni catalysts were characterized via XRD, N₂-BET, SEM, TEM and H₂-TPR. The results showed that when the loading amount of Ni was small (1% and 3%,mass ratio), it was beneficial to promote the dispersion of active metals and enhance synergistic effect between Pt-Ni bimetals. However, the active metals would agglomerate with the increase of Ni loading to 5%(mass). Compared with the Pt/HZ-75 catalyst, all the Pt-Ni/ZSM-5 catalysts exhibited excellent hydrodeoxygenation catalytic activity, and the introduction of Ni significantly improved the conversion rate and enhanced the selectivity to bicyclohexane. Furthermore, with the decrease of Pt/Ni ratio in Pt-Ni/ZSM-5 catalyst, the catalytic activity of Pt-Ni catalysts gradually increased, while the selectivity to bicyclohexane first increased and then decreased. The Pt-3Ni/HZ-75 catalyst showed the best catalytic activity and bicyclohexane selectivity at 3 MPa and 260℃. After 4 h of reaction, the conversion rate reached 100% and the bicyclohexane selectivity reached 43%.

Key words: catalysis, binary mixture, moleclar sieves, lignin, hydrodeoxygenation, hierarchical ZSM-5, bimetal

摘要：

利用等体积共浸渍法制备了级孔ZSM-5分子筛负载Pt-Ni双金属催化剂，并系统研究了不同Pt/Ni比对愈创木酚和二苯并呋喃二元混合物加氢脱氧反应性能的影响。采用XRD、N₂-BET、SEM、TEM和H₂-TPR对Pt-Ni催化剂的形貌和结构进行了表征。Ni掺入量较少时（1%和3%，质量分数），有利于促进活性金属的分散，增强Pt-Ni双金属之间的协同作用；当Ni掺入量增加到5%时，活性金属出现较严重的团聚。二元混合物加氢脱氧实验结果表明与单金属Pt/HZ-75相比，双金属Pt-Ni/ZSM-5催化剂均表现出优异的加氢脱氧催化活性，Ni的引入显著提高了反应转化速率，并提高了产物中联环己烷的选择性。随着Pt/Ni比的降低，Pt-Ni催化剂的活性逐渐增加，而联环己烷选择性先升高后降低。Pt-3Ni/HZ-75催化剂在3 MPa、260℃下表现出最佳的催化活性和联环己烷选择性，反应4 h后转化率达到100%，联环己烷选择性达到43%。

关键词: 催化, 二元混合物, 分子筛, 木质素, 加氢脱氧, 级孔ZSM-5, 双金属