催化学报

催化学报 ›› 2006, Vol. 27 ›› Issue (11): 1033-1038.

• 研究论文 • 上一篇    下一篇

固体酸催化剂SO2-4/SiO2-TiO2的制备及其催化酯化性能

张琦1,2,常杰1,王铁军1,徐莹1   

  1. 1 中国科学院广州能源研究所, 广东广州 510640; 2 中国科学技术大学热科学与能源工程系, 安徽合肥 230027
  • 收稿日期:2006-11-25 出版日期:2006-11-25 发布日期:2006-11-25

Preparation of Solid Acid SO2-4/SiO2-TiO2 and Its Catalytic Activity for Esterification

ZHANG Qi1,2, CHANG Jie1, WANG Tiejun1*, XU Ying1   

  1. 1 Guangzhou Institute of Energy Conversion, The Chinese Academy of Sciences, Guangzhou 510640, Guangdong, China; 2 Department of Thermal Science and Energy Engineering, University of Science and Technology of China, Hefei 230027, Anhui, China
  • Received:2006-11-25 Online:2006-11-25 Published:2006-11-25

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1239

被引次数

207

摘要： 分别以机械混合法和浸渍法制备了SO2-4/SiO2-TiO2固体酸催化剂,以乙醇和乙酸的酯化反应为模型反应考察了不同SiO2含量及不同温度焙烧的催化剂的活性. 结果表明,机械混合法制备的400 ℃焙烧的SO2-4/40%SiO2-TiO2催化剂活性最高,部分回流时,乙酸几乎全部转化,全回流反应100 min时,其乙酸转化率达到84%. X射线衍射分析表明, SiO2抑制了硫酸氧钛的形成; 催化剂的活性组分包括一定量的四方晶锐钛矿型TiO2、 正交晶硫酸氧钛、少量立方晶金属钛和高比表面积的SiO2. 红外光谱分析表明,添加SiO2后催化剂形成 Ti-O-Si 键,进而使SO2-4与样品表面产生强相互作用; 结合的SO2-4主要以无机螯合状双配位和有机硫酸酯两种结构形式存在. 热重-示差扫描量热分析表明, SiO2的添加使SO2-4不易脱除,同时使锐钛矿TiO2向金红石相的转变温度降低.

关键词: 硫酸, 氧化硅, 氧化钛, 固体酸催化剂, 生物油, 乙酸, 乙醇, 酯化

Abstract: Solid acid catalysts SO2-4/SiO2-TiO2 with different SiO2/TiO2 ratios and calcined at different temperatures were prepared by mechanical mixing and impregnation methods. The catalysts were used for esterification of ethanol and acetic acid. SO2-4/40%SiO2-TiO2 prepared by mechanical mixing and calcination at 400 ℃ exhibited the highest activity, and the acetic acid conversion was nearly 100% in partial reflux rectifying esterification and up to 84% in total reflux esterification, which was close to the chemical equilibrium composition. X-ray diffraction patterns indicated that SiO2 inhibited the excessive formation of titanium oxide sulfate. The combination of tetragonal crystal anatase TiO2, orthorhombic crystal titanium oxide sulfate, and cubic crystal titanium with high surface area SiO2 ensured the high activity of the catalysts. Infrared spectra showed that the addition of SiO2 helped the formation of Ti-O-Si linkage which enhanced the strong bonding of SO2-4 with the catalyst surface. The sulfate species bonded were in bidentately chelating and covalent sulfate structures. Thermogravimetric-differential scanning calorimetry proved that SO2-4 was hardly removed with the addition of SiO2 and the temperature for transformation of anatase to rutile was lowered.

Key words: sulfuric acid, silica, titania, solid acid catalyst, bio-oil, acetic acid, ethanol, esterification