添加物对钛基甲烷氧化偶联催化剂性能影响的研究Ⅰ．添加Li、La对TiO_2晶型转变的影响及其催化行为

THE EFFECT OF ADDITIVES ON THE CAIALYTIC PERFORMANCE OF TITANIUM-BASED CA TALYSTS FOR THE OXIDATIVE COUPLING OF METHANE Ⅰ.THE EFFECT OF Li AND La ADDITIVES ON THE PHASE TRANSFORMATION OF TiO_2 AND ON THE CATALYTIC PERFORMANCE

添加物对钛基甲烷氧化偶联催化剂性能影响的研究Ⅰ．添加Ｌｉ、Ｌａ对ＴｉＯ＿２晶型转变的影响及其催化行为龚茂初，陈豫，张卫东，秦代毅，陈耀强，周建略（四川大学化学系及分析测试中心，成都６１００６４）关键词：甲烷氧化偶联，ＴｉＯ＿２基催化剂，添加物，相转变...

Abstract XRD and DTA-TGA methods were used to invcstigate the phase transformation of TiO_2 in iO_2(A+R),Li/TiO_2,La/TiO_2 and Li/La/TiO_2 systcms which were used to eatalyze the oxidative coupling of methane. The reactivity and the C_2 selectivty of cach phase of TiO_2 were aiso investigat ed. It was found that when Li was added to TiO_2(A+R),the XRD pattern of Anatase vanished while that of Rutile strengthened, and no XRD pattern of any other new Ti-Li phase was detect ed. GTA and TGA curves indicated that the transformation from Anatase to Rutile Which slowly took place even at 1273 K without Li could occur at about 850 K in the prescnce of Li. It was re vealed from XRD and DTA-TGA analysis,that La had little effect on the transformation from Anatasse to Rutile. The reaction rate mcasurement showed that TiO_2(A+R)exhibited higher methane conversion than Rutile,while the later exhibited higher C_2 selectivity,and La/TiO_2 exhibit ed higher methane conversion than TiO_2(A+R)with deep methane oxidation. Then the promotion effect of Li on the selectivity of C_2 could result from the enhancement of the phase transformation from Anatase to Rutile,while ta could promote methane conversion.