CAJ | 학술논문

硅胶负载的钯-金双金属催化剂是乙烯乙酰氧基化制乙烯基乙酸酯(VA)的高选择性催化剂,本文应用平面和负载纳米颗粒模型催化剂体系研究金的助催化作用,应用低能离子散射谱、低能电子衍射、 X射线光电子能谱、反射红外吸收光谱及程序升温脱附等技术表征这些模型催化剂. 结果表明,金的主要助催化作用是隔离催化剂表面的催化活性钯原子,形成孤立的钯活性中心,从而大大抑制或消除反应物和/或产物在毗邻多原子钯中心上的深度分解,提高VA合成的选择性及活性. 同时由于形成了孤立的钯原子活性中心,反应副产物或中间物之一的一氧化碳吸附较弱,避免了催化剂表面的一氧化碳中毒,进而提高催化活性.
규효부재적파-금쌍금속최화제시을희을선양기화제을희기을산지(VA)적고선택성최화제,본문응용평면화부재납미과립모형최화제체계연구금적조최화작용,응용저능리자산사보、저능전자연사、 X사선광전자능보、반사홍외흡수광보급정서승온탈부등기술표정저사모형최화제. 결과표명,금적주요조최화작용시격리최화제표면적최화활성파원자,형성고립적파활성중심,종이대대억제혹소제반응물화/혹산물재비린다원자파중심상적심도분해,제고VA합성적선택성급활성. 동시유우형성료고립적파원자활성중심,반응부산물혹중간물지일적일양화탄흡부교약,피면료최화제표면적일양화탄중독,진이제고최화활성.
Silica supported Pd-Au bimetallic catalysts are highly selective for the acetoxylation of ethylene to vinyl acetate (VA). In this study we have used model catalysts consisting of planer surfaces and supported nanoparticles to investigate the promotional effects of Au in Pd-Au bimetallic catalysts. Low energy ion scattering spectroscopy, low energy electron diffraction, X-ray photoelectron spectroscopy, infrared reflection adsorption spectroscopy, and temperature-programmed desorption et al, were used to characterize the model systems. The catalytic performance for acetoxylation of ethylene to VA was examined for these model surfaces. In this paper, we summarize the current understanding of the promotional effects of Au in Pd-Au bimetallic catalysts for VA synthesis. The key results are that Au atoms break contiguous Pd atom ensembles at the surface into isolated Pd monomers. The absence of contiguous Pd sites significantly reduces the formation of combustion by-products and suppresses the poison effects of CO, thus enhancing the VA formation selectivity and activity.