摘要
研究了负载Ｎａ２Ｏ、Ｋ２Ｏ的γ－Ａｌ２Ｏ３催化剂在乙苯（ＥＢ）脱氢与二氧化碳转化耦合反应（ＥＢ＋ＣＯ２ＳＴＹ＋ＣＯ＋Ｈ２Ｏ）的催化活性及生成苯乙烯（ＳＴＹ）的选择性，考察了各种反应条件对催化活性的影响，并以ＮＨ３和ＣＯ２为吸附质运用微分吸附量热法表征了催化剂的表面酸碱性质。结果表明，γ－Ａｌ２Ｏ３具有较多的强酸位和较少的碱位，其对ＮＨ３的起始吸附热为１３５ｋＪｍｏｌ，吸附饱和覆盖度为２５μｍｏｌｍ２；对ＣＯ２的吸附热为１２５ｋＪｍｏｌ，吸附饱和覆盖度为０３μｍｏｌｍ２，γ－Ａｌ２Ｏ３对反应的催化活性较低。而Ｋ２Ｏ／γ－Ａｌ２Ｏ３具有较多的强碱位和较少的酸位，催化活性较好，其对ＮＨ３的起始吸附热为３０ｋＪｍｏｌ，吸附饱和覆盖度为１５０μｍｏｌｍ２；对ＣＯ２的吸附热为１４５ｋＪｍｏｌ，吸附饱和覆盖度为２７μｍｏｌｍ２。因此表明催化剂表面存在的酸、碱中心对反应具有协同作用，强碱中心对ＣＯ２的活化。
The combination of the dehydrogenation of ethylbenzene to styrene and the carbon dioxide shift-reaction has been investigated over γ-Al 2O 3 supported Na 2O, K 2O catalysts at temperatures of 600℃ in a conventional flow reactor at atomspheric pressure The catalytic reactivities of catalysts were correlated to their surface acidities and basicities, as determined by microcalorimetric adsorption of NH 3 and CO 2 It was found that γ-Al 2O 3 possesses some strong acid sites (2 5μmol/m 2) corresponding to the adsorption heat of 135kJ/mol, and less base sites (0 3μmol/m 2) with CO 2 adsorption heat around 125kJ/mol, while K 2O/γ-Al 2O 3 possesses weak acid sites (1 5μmol/m 2) with NH 3 adsorption heat around 30kJ/mol and some strong base sites (2 7μmol/m 2) with the adsorption heat of 145kJ/mol Accordingly, the γ-Al 2O 3 gives a lower reaction activity of EB+CO 2STY+CO+H 2O, while K 2O/γ-Al 2O 3 shows a higher catalytic activity The conversion of EB on K 2O/γ-Al 2O 3 is about 71 9% with 69 1% STY selectivity It may be concluded that the strong base site may be favorable for the high STY selectivity by activing CO 2 adsorpted on the catalyst surface
出处
《燃料化学学报》
EI
CAS
CSCD
北大核心
1999年第4期314-318,共5页
Journal of Fuel Chemistry and Technology
基金
国家自然科学基金
南京大学现代分析中心测试基金资助项目
关键词
氧化铝
乙苯
脱氢
二氧化碳转化
吸附量热
alumina oxides, dehydrogenation of ethylbenzene, carbon dioxide shift-reaction, microcalorimetric adsorption
