【作者】 张杰；

【导师】 沈美庆；

【作者基本信息】 天津大学 ， 化学工艺， 2006， 硕士

【摘要】 随着我国机动车保有量的逐年增加,环境问题和能源问题成为当前急需解决的问题。在全国范围内推广使用乙醇汽油将对改善大气环境和缓解能源危机有着重要的意义。但是目前,有关乙醇汽油的排放特征以及乙醇汽油对催化剂的影响尚缺乏细致研究。本论文在DPC-1型底盘测功机转鼓台架上对两台广州本田125型四冲程摩托车采用ECE40工况法提供的经典参数,对污染物排放进行定容取样法(CVS)检测。结果表明:使用E10,摩托车原机排放达不到欧Ⅱ排放标准;E10与普通汽油相比,可以显著的降低排放物中CO和HC的浓度,但对减少NOx排放量的作用不大,甚至会增加NOx排放量;E10比普通汽油会排放出更多的乙烯和乙醛并且对降低芳香族化合物排放量的作用不明显。对行驶到10000km摩托车上的三效催化剂机械分割,对其进行SEM、EPMA和TG/DTA分析,得出结论:乙醇汽油比普通汽油更容易导致催化剂的失活,失活的原因主要是积碳;催化剂上的不同位置积碳量有所不同,中间层>过渡层>边界层;贵金属活性位上的积碳量占积碳总量的很大比例,而载体酸性位上积碳量相对较小;贵金属活性位上的碳物种容易在较低温度下发生烧碳,而载体酸性位上碳物种的烧碳发生在较高的温度。再对催化剂样品进行XPS和FTIR表征分析,得出结论:E10在催化剂上的积碳物种全部以CxHyO形式存在,为苯环和烷基化合物部分氧化的产物;普通汽油的积碳物种主要以CxHy形式存在,为苯环和烷基化合物,另外还有少部分碳物种为CxHyO形式,分布在催化剂的过渡层。更多还原

【Abstract】 The emissions of pollutants from vehicle engines into the atmosphere are becoming a more and more concern in China, because of its steady increasing number. The application of ethanol-gasoline blended fuel in our country is one of means to lessen these pollutant emissions from vehicles and save fossil fuels. But till now, few data are available for showing the effects of ethanol-blended gasoline on exhaust emissions characteristics and its influence on monolith catalytic converter.In this paper, two new four-stroke motorcycles, HONDA CG125, was chosen. Wheels of those two test vehicles were supported by rollers that simulated actually driving conditions. The testing was performed on this chassis dynamometer according to ECE40 (European driving cycle). Pollutant emissions were measured for the entire ECE40 cycle with constant volume sampling (CVS). The results can be summarized: E10 can improve emissions of CO and HC to some extend; hydrocarbon species except ethanol, acetaldehyde and ethylene emissions are decreased somewhat from E10. Additionally, the effect of ethanol addition to gasoline on the improvement of aromatic emissions is not obvious.SEM, EPMA and TG-DTA were applied for the characterization of coked catalyst samples, which were obtained from motorcycles having completed a 10000 km-testing program using common gasoline and E10 fuels, respectively. Result indicates: after a 10000km-testing program, catalysis conversions of HC, CO and NOx from E10 fueled engine decreased drastically; E10 can gives rise to more negative impact on efficiencies of catalyst converter than common gasoline, because it produces more carbon deposition; the quantity of carbon deposition on the radial positions of catalytic converters is center-layer > transition-layer > edge-layer; the majority of total carbon is deposited on precious mental (PM) sites, and carbenium ions produced on PM can combust at lower temperatures.After XPS and FTIR characteristic analysis on coked catalyst samples, conclusions can be drawn: carbon species are CxHy and CxHyO, respectively on the surface of gasoline and E10 fueled; FTIR confirms the presence of aromatic rings, alkyl groups and their partial oxidation products in carbon deposition on the surface of E10 fueled.更多还原