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Development of Aluminum-Gallium Mixed Oxide Catalysts for Selective Catalytic Reduction of NOx with methane

甲烷选择性催化还原氮氧化物的铝镓混合氧化物催化剂的开发

基本信息

批准号：
15310053
负责人：
INOUE Masashi
金额：
$ 10.05万
依托单位：
Kyoto University
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (B)
财政年份：
2003
资助国家：
日本
起止时间：
2003 至 2005
项目状态：
已结题

项目摘要

Glycothermal synthesis of Ga2O3-Al2O3 solid solution was explored and it was found that the reaction of mixtures of aluminum isoproxide and gallium acetylacetonate in 1,4-butanediol or 1,5-pentanediol at 300℃ for 2 h yielded gamma-type Ga2O3-Al2O3 mixed oxides having a defect spinel structure, in which gallium ions selectively occupy the tetrahedral sites while aluminum ions preferentially occupy the octahedral sites. The Ga2O3-Al2O3 catalyst prepared by the glycothermal method had higher activity than those prepared by the corprecipitation or sol-gel method for selective catalytic reduction of Nox with methane. The activity of the catalyst prepared by the glycothermal method correlated with the ratio of the tetrahedral Ga ions to the total Ga ions and therefore it was concluded that the tetrahedral Ga ions with Al ions at the next-nearest-neighbor sites is the active site for the reaction. B-or Zn-modified solid solutions prepared by the addition of trimethyl borate or zinc acetate to … More the above-mentioned glycothermal reaction also had high activities for the deNOx reaction with methane. For the Zn-modified Ga2O3-Al2O3 catalyst, the modification rather reduced the population of the tetrahedral Ga sites but increased the crystallinity of the catalyst, which reduced the amount of adsorbed water, thus reducing the inhibitory effect of water caused by competitive adsorption of water with Nox or methane. In the selective catalytic reduction of Nox with methane, activation of methane is the rate-determining step and water is strongly adsorbed on the catalysts, thus inhibiting the catalytic activity. Therefore, the catalyst with high crystallinity had high activity. The solvothermal synthesis of the Ga2O3-Al2O3 mixed oxide in various solvents was examined and it was found that the reaction in diethylenetriamine gave the mixed oxide with high crystallinity. The catalyst prepared in diethylenetriamine had a quite high activity for selective catalytic reduction of Nox with methane. Less

对Ga2O3-Al2O3固溶体的糖热合成进行了探索，发现异丙醇铝和乙酰丙酮镓的混合物在1,4-丁二醇或1,5-戊二醇中于300℃反应2 h，得到具有缺陷尖晶石结构的γ型Ga2O3-Al2O3混合氧化物，其中镓离子选择性地结合占据四面体位点，而铝离子优先占据八面体位点。糖热法制备的Ga2O3-Al2O3催化剂比共沉淀法或溶胶-凝胶法制备的催化剂对于甲烷选择性催化还原Nox具有更高的活性。糖热法制备的催化剂的活性与四面体Ga离子与总Ga离子的比例相关，因此可以得出结论，紧邻Al离子的四面体Ga离子是反应的活性位点。通过在上述糖热反应中添加硼酸三甲酯或乙酸锌制备的硼或锌改性固溶体对于甲烷脱硝反应也具有较高的活性。对于Zn修饰的Ga2O3-Al2O3催化剂，修饰虽然减少了四面体Ga位点的数量，但提高了催化剂的结晶度，从而减少了吸附水量，从而降低了水与Nox或甲烷竞争吸附所产生的抑制作用。在甲烷选择性催化还原Nox中，甲烷的活化是决定速率的步骤，并且水强烈吸附在催化剂上，从而抑制催化活性。因此，结晶度高的催化剂具有高活性。对Ga2O3-Al2O3混合氧化物在各种溶剂中的溶剂热合成进行了考察，发现在二亚乙基三胺中反应得到了具有高结晶度的混合氧化物。以二乙烯三胺为原料制备的催化剂对于甲烷选择性催化还原Nox具有较高的活性。较少的