Abstract:

For the reaction of catalytic dehydrogenation of ethanol to produce acetaldehyde, current catalysts face the challenge of limited selectivity, particularly exhibiting poor performance in the efficient generation of acetaldehyde. Some catalysts are hindered in the dehydrogenation process due to excessive acidity, which urgently needs to be addressed. Therefore, the development of novel catalysts with high?performance surface basicity is crucial.Two composite catalysts, La₂O₂CO₃/ZnO?a and La₂O₂CO₃/ZnO?b, were prepared using the co?precipitation method and the solution combustion method. The performance of the catalysts was evaluated by varying preparation conditions such as precipitation pH, aging time, calcination temperature, and calcination time to determine the optimal synthesis parameters. Advanced characterization techniques, including Scanning Electron Microscopy, Transmission Electron Microscopy, X?ray Diffraction, and CO₂ Temperature?Programmed Desorption, were employed to thoroughly investigate the catalyst's crystal phase, morphology, surface basicity, and their relationship with catalytic performance. The optimal process conditions for ethanol dehydrogenation to acetaldehyde were investigated on the best?performing catalyst. When the precipitation pH was 9.0, the aging time was 12.0 h, the ratio of n_La to n_Zn was 1.0, and the calcination temperature was 600 ℃, the optimal preparation conditions for the solution calcination method were determined as follows: calcination time of 5.0 h, calcination temperature of 550 ℃, and n_La/n_Zn of 1.0. Under the conditions of a volume space velocity of 1.0 h?1, a reaction pressure of 1.0 MPa, and a reaction temperature of 190 ℃, La?O?CO?/ZnO?a achieved the highest acetaldehyde yield of 57.60%.

Key words: Ethanol dehydrogenation to acetaldehyde, Coprecipitation method, Solution combustion method, La₂O₂CO₃/ZnO

摘要：

针对乙醇催化脱氢制备乙醛的反应，现有催化剂存在选择性受限的问题，特别是在高效生成乙醛方面表现不佳，部分催化剂因酸度过高而阻碍脱氢过程。因此，开发具有表面碱性的新型高性能催化剂至关重要。通过共沉淀法与溶液燃烧法分别制备了La₂O₂CO₃/ZnO?a和La₂O₂CO₃/ZnO?b两种复合催化剂，通过改变沉淀pH、老化时间、煅烧温度、煅烧时间等条件对催化剂性能进行评价，确定了催化剂的最佳制备条件；利用扫描电镜、透射电镜、X射线衍射、CO₂程序升温脱附等手段，深入探究了催化剂的晶相、形貌、表面碱性及其与催化性能的关系；在最佳催化剂上考察了乙醇脱氢反应合成乙醛的最佳工艺条件。结果表明，共沉淀法的最佳制备条件：沉淀pH为9.0，老化时间为12.0 h，n_La/n_Zn=1.0，煅烧温度为600 ℃；溶液煅烧法的最佳制备条件：煅烧时间为5.0 h，煅烧温度为550 ℃，n_La/n_Zn=1.0；当体积空速为1.0 h^-1、反应压力为1.0 MPa、反应温度为190 ℃时，La₂O₂CO₃/ZnO?a上乙醛的收率最高，为57.60%。

关键词: 乙醇脱氢制乙醛, 共沉淀法, 溶液燃烧法, La₂O₂CO₃/ZnO