Zhang Yuanjing, Hou Quandong, Wang Si, Xu Enze, Zhao Shiquan, Li Feng, Yang Yusen, Wei Min
State Key Laboratory of Chemical Resource Engineering, Beijing Advanced Innovation Center for Soft Matter Science and Engineering, Beijing University of Chemical Technology, Beijing 100029, P. R. China.
ACS Appl Mater Interfaces. 2023 Jul 19;15(28):33612-33620. doi: 10.1021/acsami.3c05799. Epub 2023 Jul 7.
The hydroalkylation tandem reaction of benzene to cyclohexylbenzene (CHB) provides an atom economy route for conversion and utilization of benzene; yet, it presents significant challenges in activity and selectivity control. In this work, we report a metal-support synergistic catalyst prepared calcination of W-precursor-containing montmorillonite (MMT) followed by Pd loading (denoted as Pd-WO/MMT, = 5, 15, and 25 wt %), which shows excellent catalytic performance for hydroalkylation of benzene. A combination study (X-ray diffraction (XRD), hydrogen-temperature programmed reduction (H-TPR), transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), UV-vis, Raman, and density functional theory (DFT) calculations) confirms the formation of interfacial sites Pd-(WO)-H, whose concentration is dependent on the interaction between Pd and WO. The optimized catalyst (Pd-15WO/MMT) exhibits a CHB yield of up to 45.1% under a relatively low hydrogen pressure, which stands at the highest level among state-of-the-art catalysts. Investigations on the structure-property correlation based on FT-IR and control experiments further verify that the Pd-(WO)-H structure serves as the dual-active site: the interfacial Pd site accelerates benzene hydrogenation to cyclohexene (CHE), while the interfacial Bronsted (B) acid site in Pd-(WO)-H boosts the alkylation of benzene and CHE to CHB. This study offers a new strategy for the design and preparation of metal-acid bifunctional catalysts, which shows potential application in the hydroalkylation reaction of benzene.
苯加氢烷基化串联反应生成环己基苯（CHB）为苯的转化和利用提供了一条原子经济路线；然而，该反应在活性和选择性控制方面面临重大挑战。在本工作中，我们报道了一种通过对含钨前驱体的蒙脱石（MMT）进行煅烧然后负载钯制备的金属 - 载体协同催化剂（记为Pd - WO/MMT，其中钨含量分别为5 wt%、15 wt%和25 wt%），该催化剂对苯的加氢烷基化反应表现出优异的催化性能。结合X射线衍射（XRD）、程序升温还原（H - TPR）、透射电子显微镜（TEM）、X射线光电子能谱（XPS）、紫外可见光谱、拉曼光谱以及密度泛函理论（DFT）计算等研究证实了界面位点Pd - (WO) - H的形成，其浓度取决于钯与WO之间的相互作用。优化后的催化剂（Pd - 15WO/MMT）在相对较低的氢气压力下CHB产率高达45.1%，在同类催化剂中处于最高水平。基于傅里叶变换红外光谱（FT - IR）的结构 - 性能关联研究以及对照实验进一步证实，Pd - (WO) - H结构作为双活性位点：界面Pd位点加速苯加氢生成环己烯（CHE），而Pd - (WO) - H中的界面布朗斯特（B）酸位点促进苯与CHE烷基化生成CHB。本研究为金属 - 酸双功能催化剂的设计和制备提供了一种新策略，在苯的加氢烷基化反应中显示出潜在应用价值。
