氧化铝结构与表面性质调控及其催化甲醇脱水制二甲醚性能研究  

Alumina structure and surface property regulation for catalyzing methanol dehydration to dimethyl ether

作　　者：罗莉 陈文尧 张晶[1] 钱刚[1] 周兴贵[1] 段学志[1] LUO Li;CHEN Wenyao;ZHANG Jing;QIAN Gang;ZHOU Xinggui;DUAN Xuezhi(State Key Laboratory of Chemical Engineering,School of Chemical Engineering,East China University of Science and Technology,Shanghai 200237,China)

机构地区：[1]华东理工大学化工学院,化学工程联合国家重点实验室,上海200237

出　　处：《化工学报》2024年第7期2522-2532,共11页CIESC Journal

基　　金：上海市基础研究特区项目(22TQ1400100-15)。

摘　　要：二甲醚(DME)作为一种关键的化工原料,被广泛用于合成众多重要的化学品及能源产品。在工业生产中用于从甲醇制备DME的催化剂γ-Al_(2)O_(3)因其高效的催化性能而得到普遍应用。然而,γ-Al_(2)O_(3)的合成方法和制备条件对其催化性能有着显著的影响。目前,对于工业上常用的γ-Al_(2)O_(3)合成条件如何影响其催化性能的系统研究仍然不足。特别是,作为影响催化性能的关键因素之一,酸性位点的性质尚未形成共识。通过调控双铝法成胶过程中母液的pH,成功合成了一系列具有不同孔道结构和酸性质的γ-Al_(2)O_(3)。实验结果表明,随着母液pH的增大,γ-Al_(2)O_(3)的比表面积、孔容和孔径均呈现减小趋势。同时,γ-Al_(2)O_(3)的弱酸量逐渐减小,而中强酸量呈现先增后减的趋势。进一步结合催化性能评估结果,发现中强酸数量与甲醇脱水性能密切相关。具有最高中强酸数量的γ-Al_(2)O_(3)表现出最高的DME产率,预示中强酸位点是γ-Al_(2)O_(3)催化甲醇脱水制备DME的主要活性中心。针对具有最优性能的γ-Al_(2)O_(3)开展动力学实验分析,得到甲醇脱水的反应级数为0.78,反应活化能为83.27 kJ/mol。研究可为甲醇脱水制备DME催化剂的设计提供指导,为进一步优化工业生产条件和提高催化效率夯实基础。Dimethyl ether(DME),as a key chemical raw material,is widely used in the synthesis of a multitude of important chemical products and energy commodities.In the industrial production,γ-Al_(2)O_(3)used for the preparation of DME from methanol has been widely applied due to its high catalytic efficiency.However,the synthesis methods and preparation conditions ofγ-Al_(2)O_(3)have a significant impact on its catalytic performance.At present,there is still insufficient systematic research on how the synthesis conditions ofγ-Al_(2)O_(3)commonly used in industry affect its catalytic performance.This study successfully preparedγ-Al_(2)O_(3)with different pore structures and acidic properties by adjusting the pH of the mother liquor during the sol-gel process using the double aluminum method.The influence of acidic site properties ofγ-Al_(2)O_(3)on the performance of methanol-to-DME synthesis was systematically investigated.Characterization results revealed that,with an increase in the pH of the mother liquor,the specific surface area,pore volume,and pore size ofγ-Al_(2)O_(3)exhibited a decreasing trend.Furthermore,as the pH increased,the weak acidity ofγ-Al_(2)O_(3)gradually decreased,while the moderate-strong acidity showed an initial increase followed by a decrease.Combining the results of catalytic performance evaluation,it was found that the quantity of moderate-strong acidic sites is closely related to methanol dehydration performance.γ-Al_(2)O_(3)with the highest quantity of moderate-strong acidic sites exhibited the highest DME yield,suggesting that moderate-strong acid sites are the primary active centers forγ-Al_(2)O_(3)catalyzing methanol dehydration to produce DME.Kinetic experiments were conducted onγ-Al_(2)O_(3)with optimal performance,and the reaction order of methanol dehydration was 0.78,and the reaction activation energy was 83.27 kJ/mol.This study provides important guidance for the design of catalysts for methanol dehydration to produce DME,laying the foundation for further optimization of indu

关 键 词：氧化铝 甲醇脱水 二甲醚 酸性调控 催化剂 动力学 

分 类 号：TQ032.4[化学工程]