【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.更多还原

【Abstract】 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.更多还原