添加物对钛基甲烷氧化偶联催化剂性能影响的研究 Ⅱ．Li－La－Mn／TiO_2催化剂的催化性能及其表征

对ＴｉＯ２、Ｍｎ／ＴｉＯ２、Ｌａ／ＴｉＯ２、Ｌａ－Ｍｎ／ＴｉＯ２、Ｌｉ－Ｍｎ／ＴｉＯ２、Ｌｉ－Ｌａ／ＴｉＯ２和Ｌｉ－Ｌａ－Ｍｎ／ＴｉＯ２等系列钛基甲烷氧化偶联催化剂的催化性能进行了考察，并用ＸＲＤ和ＸＰＳ对该系列催化剂进行了表征。实验结果表明，Ｌｉ－Ｌａ－Ｍｎ／ＴｉＯ２催化剂对甲烷氧化偶联反应具有较高的反应活性和Ｃ２烃选择性。催化剂中Ｔｉ组分主要以＋４价存在；Ｌｉ组分能促进Ｌａ与ＴｉＯ２的相互作用，而形成钛酸镧，使Ｌａ组分在催化剂表面的浓度减小，而Ｌｉ组分本身则主要是以Ｌｉ２ＳＯ４状态存在于催化剂中，是Ｍｎ／ＴｉＯ２、Ｌａ／ＴｉＯ２、Ｌａ－Ｍｎ／ＴｉＯ２等催化剂的优良添加剂。Ｍｎ组分主要以低价（＋２、＋３）氧化物分布于催化剂表面，Ｌａ、Ｍｎ的添加主要是使甲烷活化，提高催化剂的活性，Ｌｉ组分的添加主要是提高甲烷氧化偶联反应的选择性即Ｃ２烃收率。

The effect of additives on the catalytic performance of titanium-based catalyst for the oxidative coupling of methaneⅡ.catalytic performance and characterization of Li La-Mn/TiO_2

The catalytic performance of Mn/TiO2La/TiO2 Li-Mn/TiO2,La-Mn/TiO2 and LiLa-Mn/TiO2 catalysts for oxidative coupling of methane(OCM)was reported. The catalysts were characterized by X-ray diffraction(XRD)and X-ray photoelectron spectroscopy (XPS ).The results shown that Li-La-Mn/TiO2 catalyst has a high reactive activity for OCM and selectivity to C2 hydrocarbon. Element Ti in the catalysts existed mainly in four valence state.Li can promote the reaction of La with TiO2 to form lanthanum titanates and decrease the concentration of La on the surface. It mainly existed in the catalysts as Li2SO4 and is an excellent promoter for TiO2based catalysts.Mn presented in the surface layer and existed in low oxidation states.La and Mn played basically a role of promoting activation of methane and increased the catalyst activity.Li increased prominently the catalytic activity and C2 selectivity.