催化学报

催化学报 ›› 2008, Vol. 29 ›› Issue (8): 758-764.

• 研究论文 • 上一篇    下一篇

钒改性对SO2-4/ZrO2-Al2O3固体酸催化剂结构与催化性能的影响

王宇红,王越敏心,李俊   

  1. 上海应用技术学院化学工程系应用催化研究所, 上海 200235
  • 收稿日期:2008-08-25 出版日期:2008-08-25 发布日期:2012-06-20

Effect of Vanadium Modification on Structure and Catalytic Properties of SO2-4/ZrO2-Al2O3 Solid Acid Catalyst

WANG Yuhong*, WANG Yuemin, LI Jun   

  1. Research Institute of Applied Catalysis, Department of Chemical Engineering, Shanghai Institute of Technology, Shanghai 200235, China
  • Received:2008-08-25 Online:2008-08-25 Published:2012-06-20

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1214

被引次数

61

摘要： 采用共沉淀法和浸渍法在不同条件下制备了V2O5-SO2-4/ZrO2-Al2O3系列固体超强酸催化剂. 使用乙酸与正丁醇酯化反应评价了催化剂活性,并通过热重、X射线衍射、红外光谱、比表面积测定和X射线光电子能谱等表征方法考察了催化剂结构和性能的关系. 结果表明,载体在0 ℃陈化,最终样品于600 ℃焙烧,钒浸渍浓度为0.005 mol/L, 且后于硫酸溶液浸渍时制得的催化剂活性最高,酯化率为99.71%, 且具有较好的重复使用性. V的引入使活性四方相ZrO2更加稳定, 0 ℃陈化促进了四方相ZrO2微晶生成, 600 ℃焙烧使催化剂既具有较多活性四方相ZrO2, 又具有较大比表面积,从而提高了催化剂活性. 催化剂中形成了固体超强酸结构,且改性后S=O吸收峰及劈裂程度增强,催化剂活性中心数目增加,Al2O3, ZrO2, SO2-4和助剂V发生了相互作用. 低温陈化虽然提高了催化剂的活性,但是略微降低了催化剂的热稳定性.

关键词: 固体酸, 五氧化二钒, 氧化锆, 氧化铝, 硫酸根, 低温陈化, 酯化反应

Abstract: The V-promoted SO2-4/ZrO2-Al2O3 solid superacid catalyst was prepared by the coprecipitation and impregnation method under different conditions. The catalytic properties of the samples were evaluated through esterification of acetic acid and n-butanol and characterized by thermogravimetry (TG),X-raydiffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), BET surface area measurement, andX-rayphotoelectron spectroscopy (XPS). The results show that among all the prepared samples the one that was calcined at 600 ℃, aged at 0 ℃, and impregnated with a solution containing 0.005 mol/L NH4VO3 after impregnation with sulfuric acid has the highest esterification rate of 99.71%. For this sample there was no significant change in the catalytic activity after being recycled 5 times (averaged 98.59%). An analysis of XRD patterns reveals that the incorporation of vanadium into tetragonal zirconia stabilizes the compound, the aging facilitates the formation of tetragonal zirconia microcrystals, and the calcination increases the reactivity of the catalyst by producing a greater fraction of active tetragonal zirconia with a larger surface area. It can be seen from the FT-IR spectra that superacid structures are formed in the catalysts and the absorption peak for theS=Obond is strengthened remarkably. The XPS results indicate that there are strong interactions between the V(Ⅴ) ions and their surroundings. The TG plots show that the samples aged at 0 ℃ exhibited less stability in despite of better catalytic activity.

Key words: solid acid, vanadium pentoxide, zirconium dioxide, aluminum oxide, sulfate, low-temperature aging, esterification