摘要论文研究了NO在MnOx-CeO2上还原产生N2O的机理。经原位红外测试和瞬态反应研究显示，N2O形成主要与Eley-Rideal机理有关，而与Langmuir-Hinshelwood 机理无关。在MnOx-CeO2上NO还原、N2O生成与N2生成过程中气体NO浓度的反应动力学级数分别为1、0、1， N2O选择性随着模拟烟气中NO浓度升高而明显降低。由于NH3与NO+O2在催化剂表面竞争吸附，使NO还原、N2O生成与N2生成过程中NH3浓度的反应动力学级数都在0～1之间，N2O选择性会随NH3浓度升高而有略微的升高。论文还探究了反应空速与N2O选择性的关系，在MnOx-CeO2上，根据NO反应机理的不同，空速大小对N2O产生的影响不同。19899
关键词  N2O选择性  NO转化率  Eley-Rideal机理  Langmuir-Hinshelwood 机理  动力学研究  瞬态反应
毕业论文设计说明书（论文）外文摘要
Title     Effect of NO Concentration on Selectivity of NH3-SCR
of NO over MnOx-CeO2 Catalyst
Abstract
The mechanism of N2O formation during NO reduction over MnOx-CeO2 was studied. In situ DRIFTS study and the transient reaction study demonstrated that N2O formation during NO reduction over MnOx-CeO2 mainly resulted from the Eley-Rideal mechanism (i.e. the reaction between over-activated NH3 and gaseous NO), and the Langmuir-Hinshelwood mechanism (i.e. the reaction between adsorbed NH3 and adsorbed NOx) did not contribute to N2O formation. The reaction orders of NO reduction, N2O formation and N2 formation over MnOx-CeO2 with respect to gaseous NO concentration were 1, 0 and 1, respectively. Therefore, N2O selectivity of NO reduction over MnOx-CeO2 remarkably decreased with the increase of gaseous NO concentration. However, the reaction orders of NO reduction, N2O formation and N2 formation over MnOx-CeO2 with respect to gaseous NH3 concentration were all higher than 0 due to the adsorption competition between NH3 and NO+O2. Therefore, N2O selectivity of NO reduction over MnOx-CeO2 slightly increased with the increase of gaseous NH3 concentration. Furthermore, the increase of gas hourly space velocity (i.e. GHSV) had a dual effect on N2O selectivity of NO reduction over MnOx-CeO2.
Keywords  N2O selectivity  NO conversion  the Eley-Rideal mechanism  the Langmuir-Hinshelwood mechanism.  steady-state kinetic study  transient reaction
目  次
1    引言    5
1.1  N2O的来源与危害    5
1.2  NOx选择性催化还原技术    5
1.3  低温NH3-SCR催化剂    5
1.4  研究课题的提出与内容    5
2  实验部分    5
2.1  实验仪器与药品    5
2.2  MnOx-CeO2催化剂的制备    5
2.3  催化剂活性评价    5
2.4  催化剂表征    5
3  实验结果与讨论    5
3.1  催化剂活性评价    5
3.2  瞬态反应    5
3.3  反应动力学研究    5
3.4  空速对N2O选择性的影响    5
结论    5
致谢    5
参考文献    5
1    引言
1.1  N2O的来源与危害
N2O（氧化亚氮，俗称“笑气”）在地球大气中微量存在。N2O会在大气氮循环中自然产生，同时也存在多种自然排放源，如土壤中的微生物活动，自然状态下的树木等都会向大气排放N2O[1]。虽然自然排放是大气中N2O的主要来源，但从十九世纪起由于人类的工业活动，大气中N2O量开始急剧增加，这意着原存于大气N2O源汇之间的自然平衡已经被打破。研究表明，每年单位体积大气中的N2O会增加0.5 ppb~0.9 ppb个数量级[2]。 NOx浓度对MnOx-CeO2催化剂NH3-SCR反应选择性的影响:http://www.751com.cn/huaxue/lunwen_11471.html