Ag Alloyed Pd Single-Atom Catalysts for Efficient Selective Hydrogenation of Acetylene to Ethylene in Excess Ethylene
Ag Alloyed Pd Single-Atom Catalysts for Efficient Selective Hydrogenation of Acetylene to Ethylene in Excess Ethylene
复制标题
过量乙烯中乙炔高效选择性加氢制乙烯的银合金钯单原子催化剂
DOI：
10.1021/acscatal.5b00700
复制
发表时间：
2015-06-01
期刊：
影响因子：
12.9
通讯作者：
Zhang, Tao
中科院分区：
文献类型：
--
作者：
Pei, Guang Xian;Liu, Xiao Yan;Zhang, Tao
富乙烯流中乙炔的半加氢是一个具有重要工业意义的过程。传统的负载型单金属钯催化剂具有较高的乙炔转化率，但由于过度加氢和积碳的形成，其对乙烯的选择性极低。在此，我们通过一种简单的初湿共浸渍法制备了一系列负载在硅胶上的银合金化钯单原子催化剂（钯含量仅为百万分之几），并将其应用于接近工业前端条件下富乙烯流中乙炔的选择性加氢反应。在较宽的温度范围内实现了高乙炔转化率和对乙烯的高选择性，超过了我们之前报道的类似的金合金化钯单原子体系。原位红外光谱和原位X射线光电子能谱表明，随着还原温度的升高，AgPd纳米粒子发生了重构，并且电子从银转移到钯。微量热法和X射线吸收近边结构测量结果支持了合金化的钯和银之间的几何和电子协同效应。动力学研究为这些AgPd/SiO₂催化剂中活性位点的性质提供了有价值的见解，从而为这些双金属催化剂在富乙烯条件下对乙炔选择性加氢表现优异同时减少贵金属使用的关键因素提供了证据。
Semihydrogenation of acetylene in an ethylene-rich stream is an industrially important process. Conventional supported monometallic Pd catalysts offer high acetylene conversion, but they suffer from very low selectivity to ethylene due to overhydrogenation and the formation of carbonaceous deposits. Herein, a series of Ag alloyed Pd single-atom catalysts, possessing only ppm levels of Pd, supported on silica gel were prepared by a simple incipient wetness coimpregnation method and applied to the selective hydrogenation of acetylene in an ethylene-rich stream under conditions close to the front-end employed by industry. High acetylene conversion and simultaneous selectivity to ethylene was attained over a wide temperature window, surpassing an analogous Au alloyed Pd single-atom system we previously reported. Restructuring of AgPd nanoparticles and electron transfer from Ag to Pd were evidenced by in situ FTIR and in situ XPS as a function of increasing reduction temperature. Microcalorimetry and XANES measurements support both geometric and electronic synergetic effects between the alloyed Pd and Ag. Kinetic studies provide valuable insight into the nature of the active sites within these AgPd/SiO2 catalysts, and hence, they provide evidence for the key factors underpinning the excellent performance of these bimetallic catalysts toward the selective hydrogenation of acetylene under ethylene-rich conditions while minimizing precious metal usage.