H4SiW12O40/SiO2催化正丁醛自缩合反应

正丁醛自缩合合成辛烯醛是工业生产辛醇的重要步骤之一。首先考察了3种杂多酸H₃PW₁₂O₄₀、H₄SiW₁₂O₄₀和H₃PMo₁₂O₄₀对正丁醛自缩合反应的催化性能，发现H₄SiW₁₂O₄₀的催化性能最好。其次，利用浸渍法制备了负载型H₄SiW₁₂O₄₀催化剂，考察了载体和制备条件对催化剂性能的影响，确定以SiO₂为载体，H₄SiW₁₂O₄₀负载量为50%（质量分数），在150℃焙烧2 h的制备条件。探讨了反应条件对催化剂性能的影响，确定了适宜反应条件：催化剂与正丁醛的质量比为0.15，反应温度120℃，反应时间6 h。在此条件下，正丁醛的转化率为90.4%，辛烯醛的选择性为89.2%。通过对催化剂进行ICP-AES分析和XRD表征，发现活性组分流失是造成催化剂稳定性差的主要原因。为减缓H₄SiW₁₂O₄₀的流失，以[emim]BF₄离子液体为模板剂，采用溶胶-凝胶法制备了H₄SiW₁₂O₄₀/SiO₂催化剂，实验结果表明，催化剂稳定性有一定程度的提高。

n-Butyraldehyde aldol self-condensation catalyzed by H4SiW12O40/SiO2

Aldol self-condensation of n-butyraldehyde to 2-ethyl-2-hexenal is one of the important processes for industrial production of 2-ethyl hexanol. Firstly, the catalytic performance of H₃PW₁₂O₄₀, H₄SiW₁₂O₄₀ and H₃PMo₁₂O₄₀ was evaluated and the results showed that H₄SiW₁₂O₄₀ presented the best catalytic activity. Secondly, supported H₄SiW₁₂O₄₀ catalysts were prepared with the impregnation method and the influence of the kind of support and preparation process parameters on catalyst performance was investigated. The suitable preparation conditions were determined as follows: taking SiO₂ as support, loading of H₄SiW₁₂O₄₀= 50% (mass), calcination temperature of 150℃ and calcination time of 2 h. The effect of reaction conditions on the catalyst performance of H₄SiW₁₂O₄₀/SiO₂ was also studied and the suitable reaction conditions was determined as follows: mass ratio of catalyst to n-butyraldehyde 0.15, reaction temperature of 120℃ and reaction time of 6 h. Under the above conditions, the conversion of n-butyraldehyde and the selectivity to 2-ethyl-2-hexenal were 90.4% and 89.2%, respectively. However, the reusability of H₄SiW₁₂O₄₀/SiO₂ catalyst was poor. Analysis of ICP-AES and XRD demonstrated that the loss of active species H₄SiW₁₂O₄₀ was the main reason. In order to decrease the loss of H₄SiW₁₂O₄₀, H₄SiW₁₂O₄₀/SiO₂ catalyst was prepared with the sol-gel method using [emim]BF₄ ionic liquid as template. The activity test result showed that the reusability of the prepared catalyst was improved to some extent.