甲醇脱水制二甲醚催化剂的研究进展

Research Progress of Catalysts for Methanol Dehydration to Dimethyl Ether

甲醇脱水制二甲醚为固体酸催化反应,目前该反应常用的固体酸催化剂有γ-Al_(2)O_(3)和分子筛。γ-Al_(2)O_(3)表面存在弱酸中心或中等强度酸中心,该催化剂有较好的初始催化活性,但其活化所需的反应温度较高,低温活性差,可操作温度窄,耐水稳定性差。分子筛表面有许多强酸位点,导致生成物不易从催化剂表面脱附;当反应温度过高时,副产物会明显增多,积炭严重,从而降低了二甲醚的选择性,容易致使催化剂失活。为改善两类催化剂的催化性能,研究人员进行了各种改性研究,催化剂改性后的活性、选择性和稳定性均在一定程度上有所提高。基于此,综述了近年来关于γ-Al_(2)O_(3)和分子筛催化剂的改性研究,总结并展望了甲醇脱水制二甲醚催化剂的发展方向。

The reaction of methanol dehydration to dimethyl ether is a solid acid catalytic reaction,in which the commonly used solid acid catalysts areγ-Al_(2)O_(3)and molecular sieve at present.Forγ-Al_(2)O_(3),with the presence of weak or medium-strength acid centers on the surface,it has good initial catalytic activity,but its activation requires a high reaction temperature,poor low temperature activity,narrow operable temperature,and poor water stability.For molecular sieve,there are many strong acidic sites on its surface,which makes it difficult for the products to desorb from the surface of the catalyst.When the reaction temperature is too high,the by-products increase significantly,and the carbon deposition is serious,which reduces the selectivity of dimethyl ether and the catalyst is easy to deactivate.In order to improve the catalytic performance of these two catalysts,various modification studies were carried out on them.The activity,selectivity and stability of the modified catalysts were improved to a certain extent.The modification ofγ-Al_(2)O_(3)and molecular sieve catalysts in recent years was reviewed.The development direction of methanol dehydration catalysts was summarized and prospected.