活性炭催化碳酸二甲酯水解行为的研究

以无氯Cu/AC催化剂中活性炭载体为研究对象，对活性炭上DMC水解反应条件进行了考察，并通过Boehm滴定法和XPS对活性炭上DMC水解活性位点进行了分析。结果表明，温度的升高和水含量的增加对DMC水解有较大的促进作用，较高的压力和CO₂气氛对DMC水解有一定的抑制作用，甲醇量和CO、O₂、N₂气氛对DMC水解影响较小。不同条件处理的活性炭表面基团种类、数量均有较大变化，HNO₃处理使活性炭碱性基团含量下降，羧基等酸性含氧官能团含量明显增加，总酸量最高可达1.88 mmol·g^-1；先HNO₃后NaOH处理的活性炭上酸性基团含量大量减少，表面碱性基团含量则有较大提高，总碱量最高可达1.69 mmol·g^-1。特别地，活性炭表面碱性基团是催化DMC水解的活性位点，在活性炭碱性基团含量由0.16增加到1.69 mmol·g^-1的过程中，DMC水解程度由2.5%增加到了31.7%，而酸处理可以有效降低活性炭表面碱性基团含量，抑制其催化DMC的水解性能。

Study on the Hydrolysis of Dimethyl Carbonate on Activated Carbon

The hydrolysis conditions of DMC and the hydrolytic active sites on activated carbon were investigated. The results showed that raising the temperature or increasing water content could promote the hydrolysis of DMC, but increasing the pressure or carbon dioxide atmosphere inhibited the reaction, and no significant effect of methanol content or CO, O₂, N₂ atmosphere on the hydrolysis of DMC. The kinds and numbers of surface groups on activated carbon have great changes after different acid and alkali treatment. HNO₃ treatment could decrease the surface alkaline groups and increase acidic oxygen functional group, total acidity could reach 1.88 mmol·g^-1, while the surface content of alkaline groups could reach 1.69 mmol·g^-1 after acid-base treatment. Futhermore, the acidic functional groups do not have DMC hydrolytic activity, while the alkaline groups are the main hydrolytic active sites on the activated carbon. When the content of basic groups increased from 0.16 to 1.69 mmol·g^-1, the hydrolysis degree of DMC increased from 2.5% to 31.7%. Acid treatment could reduce the content of alkaline groups and inhibit the hydrolysis performance of DMC on activated carbon.