SO42-/TiO2-SiO2 mixed oxide catalyst, I:: Synthesis, characterization, and acidic properties
SO42-/TiO2-SiO2 mixed oxide catalyst, I:: Synthesis, characterization, and acidic properties
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DOI：
10.1006/jcis.1999.6245
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发表时间：
1999-08-01
影响因子：
9.9
通讯作者：
Mishra, HK
中科院分区：
文献类型：
--
作者：
Parida, KM;Samantaray, SK;Mishra, HK
将二氧化钛-硅胶浸泡在所需体积的硫酸中，然后干燥，制备了一系列硫酸盐掺杂的二氧化钛-二氧化硅复合氧化物。以正硅酸乙酯(TEOS)和正钛酸丁酯(TBOT)为原料，在pH值为3的条件下，通过等摩尔比的水解法制备了复合氧化物凝胶。经723K焙烧4h后，用X射线衍射仪、傅立叶变换红外光谱、比表面积法和Hammett指示剂法对材料的表面酸强度进行了表征。催化活性测试在固定床催化反应器(I.D.)中进行。=10 mm)，而异丙苯裂解/脱氢反应在微脉冲反应器中进行。X射线衍射结果表明，二氧化钛-二氧化硅混合物为非晶态，晶化开始于硫酸盐化。从FT-IR数据可以看出，混合氧化物的表面同时含有桥联羟基和正羟基。材料的比表面积变化不大，在50m(2)/g范围内，4wt%SO42-/TiO2-SiO_2的酸强度比100%浓H_2SO_4强。在异丙醇转化的情况下，丙酮的低选择性表明弱碱性中心的存在，而甲醇在所有固体上的转化表明脱水遵循平行和连续的路径。异丙苯裂解与催化剂的酸性有很好的相关性。(C)1999年学术出版社。
A series of sulfate-doped titania-silica mixed oxides have been prepared by immersing titania-silica gel in the required volume of sulfuric acid, followed by drying. The mixed oxide gel is obtained by hydrolyzing an equimolar mixture of tetraethylorthosilicate (TEOS) and tetrabutylorthotitanate (TBOT) at pH 3. The materials, after calcining at 723 K for 4 h, are characterized by XRD, FT-IR, the BET method, and surface acid strength by the Hammett indicator method. The catalytic activity tests are carried in a fixed bed catalytic reactor (i.d. = 10 mm) for alcohol conversion, whereas cumene cracking/dehydrogenation reactions are carried out in a micropulse reactor. XRD results shows that the titania-silica mixture is amorphous and the crystallization starts with sulfation. The surface of the mixed oxide contains both bridged and normal hydroxyl groups, as observed from FT-IR data. The surface area of the material is not much altered by sulfation and lies within 50 m(2)/g, The acid strength of 4 wt% SO42-/TiO2-SiO2 is found to be stronger than that of 100% concentrated H2SO4. In the case of 2-propanol conversion, low acetone selectivity indicates the presence of weak basic sites, whereas methanol conversion over all solids shows that dehydration follows a parallel and consecutive pathway. A good correlation is found between the cumene cracking and the acidity of the catalysts. (C) 1999 Academic Press.