助剂Li对CO2气氛下Fe-Li/AC催化剂上乙苯脱氢反应性能的影响  

Effects of Li Promoter on the Catalytic Performance of Fe-Li/AC for Ethylbenzene Dehydrogenation in the Presence of CO_2

作　　者：陈树伟[1,2] 秦张峰[1] 孙爱灵[1] 王建国[1] 

机构地区：[1]中国科学院山西煤炭化学研究所煤转化国家重点实验室,山西太原030001 [2]太原理工大学化学化工学院,山西太原030024

出　　处：《催化学报》2009年第4期359-364,共6页

基　　金：国家自然科学基金(20676140);国家重点基础研究发展计划(973计划,2006CB202504);中科院知识创新方向项目(KJCX2.YW.H16);山西省自然科学基金(2008011022)

摘　　要：对CO2气氛下Fe-Li/AC催化剂上的乙苯脱氢反应性能进行了详细研究.N2吸附-脱附、CO2程序升温脱附和X射线衍射表征结果表明,助剂Li不仅增加了催化剂比表面积和活性组分分散性,而且增强了催化剂碱性和CO2吸附能力,从而提高了Fe/AC对乙苯脱氢的催化性能.助剂Li能显著提高Fe/AC催化剂的乙苯脱氢活性和CO2的促进作用,抑制催化剂的失活.在Fe(3.0)-Li(0.6)/AC催化剂(Fe和Li的负载量分别为3.0和0.6 mmol/g)上,550 oC、接触时间为3.57(g·h)/mol和CO2/乙苯摩尔比为20的条件下,苯乙烯收率可达62.9%,选择性为96.2%.CO2气氛下的苯乙烯收率显著高于N2气氛下的,归因于CO2能保持催化剂表面铁物种的高价态,并通过逆水煤气变换反应在线除去脱氢反应生成的氢.Dehydrogenation of ethylbenzene（EB） to styrene（ST） under CO2 was investigated over the activated carbon（AC）-supported iron catalyst with a Li promoter（Fe-Li/AC）.N2 physical adsorption and X-ray diffraction showed that the Li promoter can increase the catalyst surface area and the dispersion of iron active species.CO2 temperature-programmed desorption suggested that Li can enhance the basicity of Fe/AC and CO2 adsorption on the catalyst.The addition of Li as promoter greatly improves the catalytic activity of Fe/AC and the coupling effect of CO2 and suppresses the catalyst deactivation for EB dehydrogenation under CO2.The ST selectivity and yield reach 96.2% and 62.9%,respectively,during EB dehydrogenation over the catalyst Fe（3.0）-Li（0.6）/AC（the loadings of Fe and Li being 3.0 and 0.6 mmol/g,respectively） at 550 oC,contact time of 3.57（g-h）/mol,and CO2/EB mole ratio of 20.Higher ST yield can be obtained for EB dehydrogena-tion under CO2 than that under N2,which is attributed to that CO2 serves as a weak oxidant for keeping the high valence state of iron species in the catalyst and eliminating the hydrogen produced by EB dehydrogenation.

关 键 词：助剂 锂 二氧化碳 铁 活性炭 乙苯脱氢 苯乙烯 耦合反应 

分 类 号：O643.32[理学—物理化学]