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高分散Ru/Si_(3)N_(4)催化剂的制备及其在CO_(2)加氢中的应用

Preparation of highly dispersed Ru/Si3N_(4) catalysts and their application in CO_(2) hydrogenation
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摘要 氮化硅是一种良好的载体,具有较高的水热稳定性和机械稳定性,其表面的氨基基团能够较好地锚定金属,显著提高金属分散度。但是,商品氮化硅比表面积较低,对金属分散作用仍然有限。因此,以自制的高比表面积氮化硅(Si_(3)N_(4))为载体,通过浸渍法制备了不同Ru负载量(质量分数分别为0.5%、1.0%和2.0%)的催化剂(分别为0.5%Ru/Si_(3)N_(4)、1.0%Ru/Si_(3)N_(4)和2.0%Ru/Si_(3)N_(4)),并以商品氮化硅(Si_(3)N_(4)-C)为载体制备了2.0%Ru/Si_(3)N_(4)-C催化剂作为对照组。表征了催化剂的理化性质,测试了其在300℃、0.1 MPa下的CO_(2)加氢反应活性。结果显示,与Si_(3)N_(4)-C相比,Si_(3)N_(4)的比表面积较高(502 m^(2)/g),Si_(3)N_(4)作为载体显著提高了金属分散度,降低了金属粒径,催化剂暴露出更多的活性位点。0.5%Ru/Si_(3)N_(4)的金属粒径较小,展现出强的H_(2)吸附能力,H难以解吸,抑制了中间物种CO加氢生成CH_(4)。随着Ru负载量增加,金属粒径增大,催化剂的CH_(4)选择性更好。Ru/Si_(3)N_(4)系列催化剂中,2.0%Ru/Si_(3)N_(4)的CH_(4)选择性较高(98.8%)。空速为10000 m L/(g·h)时,0.5%Ru/Si_(3)N_(4)的CO选择性为88.2%。与2.0%Ru/Si_(3)N_(4)相比,2.0%Ru/Si_(3)N_(4)-C的金属粒径更大,活性位点较少,活性更低。2.0%Ru/Si_(3)N_(4)和2.0%Ru/Si_(3)N_(4)-C的CO_(2)转化率分别为53.1%和9.2%。Si_(3)N_(4)有效提高了金属分散度,提高了催化剂的CO_(2)加氢反应活性;通过调控Ru负载量控制催化剂金属粒径,可实现对产物CO或CH_(4)选择性的调控。 Silicon nitride is an excellent catalyst support with high hydrothermal and mechanical stability.The amino groups on its surface can effectively anchor metals,significantly enhancing metal dispersion.However,commercial silicon nitride has a relatively low surface area,limiting its effectiveness in metal dispersion.Therefore,high-surface-area self-prepared silicon nitride(Si_(3)N_(4))was used as a support to prepare catalysts(0.5%Ru/Si_(3)N_(4),1.0%Ru/Si_(3)N_(4) and 2.0%Ru/Si_(3)N_(4),respectively)with different Ru loadings(0.5%,1.0%,and 2.0%by mass fraction,respectively)via the impregnation method.Additionally,2.0%Ru/Si_(3)N_(4)-C catalyst was prepared using commercial silicon nitride(Si_(3)N_(4)-C)as a control.Physicochemical properties of the catalysts were characterized,and their activities in the CO_(2) hydrogenation reaction at 300℃and 0.1 MPa were tested.The results show that compared with Si_(3)N_(4)-C,Si_(3)N_(4) has a higher surface area(502 m^(2)/g),significantly improving metal dispersion and reducing metal particle size.Si_(3)N_(4)-based catalysts expose more active sites.The metal particle size of 0.5%Ru/Si_(3)N_(4) is small,and the catalyst exhibits strong H2 adsorption capacity,and thus H is difficult to desorption,which inhibits the hydrogenation of CO intermediates to CH_(4).As the Ru loading increases,the metal particle size increases,and the CH_(4) selectivity of the catalysts is better.Among the Ru/Si_(3)N_(4) catalysts,2.0%Ru/Si_(3)N_(4) shows higher CH_(4) selectivity(98.8%).At a space velocity of 10000 mL/(g·h),the CO selectivity of 0.5%Ru/Si_(3)N_(4) is 88.2%.Compared with 2.0%Ru/Si_(3)N_(4),2.0%Ru/Si_(3)N_(4)-C has larger metal particle size,fewer active sites,and lower activity.The CO_(2) conversion rates of 2.0%Ru/Si_(3)N_(4) and 2.0%Ru/Si_(3)N_(4)-C are 53.1%and 9.2%,respectively.Si_(3)N_(4) effectively improves metal dispersion,enhancing the catalytic activity in CO_(2) hydrogenation.By adjusting the Ru loading to control the metal particle size of the catalyst,the selectivity of the product CO or CH_(4) can be controlled.
作者 颜琳琳 魏宇学 张成华 相宏伟 李永旺 YAN Linin;WEI Yuxue;ZHANG Chenghua;XIANG Hongwei;LI Yongwang(Sinopec Research Institute of Petroleum Processing Co.,Ltd.,Beijing 100083,China;Sinopec Maoming Petrochemical Co.,Ltd.,Maoming 525000,Guangdong,China;School of Chemistry and Chemical Engineering,Anhui University,Hefei 230601,Anhui,China;National Energy Center for Coal to Liquids,Synfuels China Co.,Ltd.,Beijing 101407,China;State Key Laboratory of Coal Conversion,Institute of Coal Chemistry,Chinese Academy of Sciences,Taiyuan 030001,Shanxi,China)
出处 《低碳化学与化工》 CAS 北大核心 2024年第3期9-17,共9页 Low-Carbon Chemistry and Chemical Engineering
基金 国家自然科学基金(22179001,91545109)。
关键词 CO_(2)加氢 Ru/Si_(3)N_(4)催化剂 CH_(4)选择性 CO选择性 CO_(2)hydrogenation Ru/Si_(3)N_(4)catalysts CH_(4)selectivity CO selectivity
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