【作者】 任攀杰；

【导师】 李哲；

【作者基本信息】 太原理工大学 ， 生物化工， 2008， 硕士

【摘要】 随着石油储量的日益减少以及汽车工业的快速发展，传统车用燃料汽油、柴油的供应日益紧张，为此世界各国纷纷寻找清洁的替代燃料来替代传统的车用燃料汽油和柴油来摆脱对石油的过分依赖，以缓解车用燃料的紧张供求矛盾。我国也日益关注乙醇燃料车的开发，目前国家已经制定了相关规划，在部分地区开始推广乙醇汽油车。乙醇燃料虽然其本身不含硫、氮、磷等杂质以及乙醇燃料车尾气中的CH、CO及NO_X的含量较汽油车少而被誉为清洁燃料。但乙醇燃料车尾气中未完全燃烧的乙醇以及乙醇燃烧的中间产物醛、酮的含量明显增加，醇和含氧化合物为刺激性气体，有很高的光化学活性，是生成光化学烟雾的主要前驱体之一，另外甲醛、乙醛具有遗传毒性。因此，开展乙醇燃料车尾气净化研究有着十分重要的意义。研究和开发质优价廉的催化剂并使之能够完全催化氧化乙醇及其中间燃烧副产物尾气是乙醇燃料车在全国推广应用的一个重要前提。由于乙醇燃料汽车尾气净化的对象主要是乙醇、乙醛等低分子含氧有机物，且尾气温度低，所以要求净化催化剂具有良好的深度氧化性能和低温活性。本课题在前期工作的基础上，试图减少贵金属用量或者完全不用贵金属而用过渡金属等来代替贵金属作为催化剂的活性组分。在大量实验的基础上，结果发现，以γ-Al₂O₃-TiO₂复合氧化物为催化剂的载体，以质量含量为5％的过渡元素V为催化剂的活性组分的催化剂上乙醇、乙醛的催化氧化有较高的反应活性，并对催化剂进行了XRD、BET表征。得出结论如下：（1）催化剂的制备工艺对催化剂的性能有很大的影响。V浸渍时间12h，焙烧温度500℃，焙烧时间5h的催化剂的性能最佳，其T₅₀，T₉₅分别为170℃，215℃。（2）条件实验对催化剂的性能也有很大的影响。氧气含量在5％-8％范围内、乙醇进料浓度小于1000ppm、空速在24000h^-1时，催化剂上乙醇的催化氧化效果最好。（3）5％V／Al₂O₃-TiO₂催化剂上甲醇、乙醇和乙醛的转化率都比较高，其中，甲醇的活性最好，在125℃时，转化率已经超过50％，其次是乙醛和乙醇。三者在175℃以上时其转化率均达到95％以上，说明V／Al₂O₃-TiO₂催化剂且对多种污染物具有良好的同时净化效果。（4）在标准5％V/Al₂O₃-TiO₂催化剂中，三氧化铝是以γ-Al₂O₃的形式存在的，二氧化钛是以锐钛矿型的晶体结构存在的，而含V物种主要是以V₂O₅形式存在。（5）不同焙烧温度催化剂的XRD表明，焙烧温度低于500℃的催化剂的晶体结构没有发生变化，700℃的催化剂中的YiO₂晶体结构由锐钛矿型转化为金红石型，V₂O₅的V化合价也发生了变化，此催化剂的活性有明显下降的趋势。（6）不同V含量催化剂的XRD表明，V含量在1％-5％范围内时，V在载体上呈高度分散状态，当V含量增加到10％时，有微弱的V₂O₅衍射峰，V含量再增加时，V₂O₅的衍射峰强度逐渐增强。更多还原

【Abstract】 Supply of gasoline and diesel becomes lack increasingly with oil reserves dwindling as well as rapid development of the automobile industry, many countries around the world are looking for the clean alternative fuels to replace traditional gasoline and diesel for getting rid of excessive oil reliance in order to easing tense demand and supply of fuels. China was also concerned about development of the ethanol-fuel automobiles increasingly, and had developed a relevant plan, began to promote ethanol petrol automobiles in some areas of china. Although the ethanol fuel itself doesn’t include sulfur, nitrogen, phosphorus, other impurities etc and CH, CO and NO_x contents of the ethanol-fuel automobiles exhaust less than gasoline and diesel automobiles, ethanol not fully combusted and acetaldehyde, ether etc of the ethanol fuel automobile exhaust increased obviously. Alcohol and oxygenated compounds are irritated gases, and had a high photochemical activity, was also one of main precursors of photochemical smog formations, what was worse was that formaldehyde and acetaldehyde had a genetic toxicity. Therefore, the ethanol fuel automobile exhaust purification research had become a very important subject. How to find a high-quality catalyst which can deeply oxidate ethanol fuel was an important research subject, It was also a key factor that the ethanol fuel automobile was extensively used in the country. Objects of the ethanol fuel automobile exhaust purification were ethanol, acetaldehyde, ether etc small molecular oxygenated organic compounds, and exhaust temperature of the ethanol fuel automobile was low, so it required purification catalyst which had good performance and low temperature oxidation activity.We tried to reduce amount of precious metals or without precious metals fully for active components of catalysts to replace precious metals on the basis of our preparatory work. Research results found that the 5%V/Al₂O₃ -TiO₂ catalyst had higher reactivity on ethanol and acetaldehyde on the basis of large experimental results .At the same time supports and catalysts were characterized by XRD and BET. The conclusions were as follows:（1） Preparation conditions of catalysts greatly affected performance of catalysts . Activity of catalyst prepared by soaking V 12h, calcination temperature and time at 500℃and 5h respectively was the best, T₅₀, T₉₅ of catalyst were only 170℃, 215℃respectively.（2） Reaction conditions also greatly affected performance of catalysts . 5% -8% oxygen content, less than 1000ppm ethanol feed concentration and 24000 h^-1 space velocity were the best reaction condition of ethanol catalytic oxidation over 5%V/Al₂O₃ -TiO₂ catalyst .（3） Methanol, ethanol and acetaldehyde had high conversion over the 5% V/Al₂O₃-TiO₂ catalyst. Activity of methanol was the best, the conversion rate had been over 50% at 125℃, following conversions of acetaldehyde and ethanol.（4）γ-Al₂O₃ and TiO₂ of composite supportγ-Al₂O₃-TiO₂ existed in the form ofγ-Al₂O₃ and anatase crystal structure respectively.（5） XRDs of different calcination temperature catalysts showed that the crystal structure of catalysts had not changed under 500℃, the crystal structure of TiO₂ of the catalyst had changed from anatase to red-spar when calcination temperature of catalyst at 700℃, V valence of V₂O₅ had also changed at the same time.（6） XRDs of different V content catalysts showed that V decentralized highly on support during the 1%-5% V content range , when V content up to 10 percent, XRD of catalyst showed a slight V₂O₅ diffraction peaks, intensity of the diffraction peaks further strengthened with V content increasing.更多还原