Cs-P酸碱双功能材料制备及其催化合成丙烯酸甲酯工艺研究

发布时间：2018-03-25 21:43

  本文选题：醋酸甲酯　切入点：丙烯酸甲酯　出处：《中国地质大学(北京)》2017年博士论文

【摘要】：丙烯酸甲酯是一种重要的精细化工原料,广泛应用于粘合剂、絮凝剂、涂料、纺织、制革、制药、造纸和高吸水性树脂等领域。醋酸甲酯和甲醛经过羟醛缩合反应一步法合成丙烯酸甲酯是一种环境友好型的绿色合成工艺。此外,随着现代煤化工的快速发展,甲醇和醋酸产能出现严重过剩,开发新的下游产品和拉长化工产业链是解决产能过剩的有效途径。因此对该工艺的研究具有重要的学术价值和现实意义。研究和开发高活性,高选择性的催化剂是实现该工艺工业化的关键课题,本论文针对酸碱双功能催化剂的设计与制备及反应过程的关键科学问题进行系统的基础研究;主要研究工作如下:(1)采用等体积浸渍法制备了Cs-P/γ-Al2O3酸碱双功能催化剂。通过XRD、XPS、SEM、TEM、FT-IR和N2吸脱附等对催化剂的微观形貌、结构及表面活性中心分布状态进行分析,表征结果显示Cs-P/γ-Al2O3酸碱双功能催化剂是一种介孔材料;Cs、P活性组分在载体表面形成磷酸盐、偏磷酸盐和焦磷酸盐等多种磷酸盐结构。催化剂表面的酸碱特性决定催化剂的活性,通过CO2/NH3-TPD对催化剂的酸碱性进行表征,发现P可有效调控催化剂表面的酸碱特性,随着P负载量的增加催化剂的酸碱强度降低。采用固定床反应装置对Cs-P/γ-Al2O3催化剂的催化活性进行评价,考察负载量、载体和焙烧温度对催化性能的影响规律,结果显示10%Cs-5%P/γ-Al2O3催化剂在550℃焙烧后表现较好的催化活性,丙烯酸甲酯的收率和选择性分别达到44.3%和94%。(2)利用响应面法(RSM)对催化反应工艺参数进行合理优化。构建丙烯酸甲酯收率与反应温度、酯醛比和反应时间之间响应关系的二次多项式模型,并用于分析各因素及其交互关系对响应值的影响规律。该模型具有很高的可靠性和精密度,可用于对反应参数进行合理的优化和预测。(3)通过掺杂过渡金属氧化物对Cs-P/γ-Al2O3催化剂改性,评价结果显示Cs-P-W/γ-Al2O3催化剂表现出较好的催化活性。表征结果表明Cs-P-W/γ-Al2O3催化剂表面形成的CsW2O6结构促进了醋酸甲酯与甲醛反应,同时CsW2O6结构具有较好的热稳定性。Cs-P-W/γ-Al2O3催化剂经过长周期的寿命评价,累计反应1600h,再生催化剂的活性没有明显的降低,表现出较好的循环使用性。(4)对优化后的催化剂进行公斤级放大制备,并在120L/d移动床反应装置上进行放大实验,为中试放大实验做准备。
[Abstract]:Methyl acrylate is an important fine chemical raw material, widely used in adhesives, flocculants, coatings, textiles, tanning, pharmaceutical, The synthesis of methyl acrylate from methyl acetate and formaldehyde through hydroxaldehyde condensation is an environmentally friendly green synthesis process. In addition, with the rapid development of modern coal chemical industry, There is serious excess capacity in methanol and acetic acid, so developing new downstream products and elongating chemical industry chain is an effective way to solve overcapacity. Therefore, the research on this process has important academic value and practical significance, and research and development of high activity. High selectivity catalyst is the key to realize the industrialization of the process. In this paper, the design and preparation of acid-base bifunctional catalysts and the key scientific problems in the reaction process are systematically studied. The main work is as follows: (1) Cs-P/ 纬 -Al _ 2O _ 3 acid-base bifunctional catalysts were prepared by iso-volume impregnation method. The microstructure, structure and distribution of surface active sites of the catalysts were analyzed by XRDX, XRDX, XPS, SEMX, TEMT-IR and N2 adsorption and desorption. The characterization results show that the Cs-P/ 纬 -Al 2O 3 acid-base bifunctional catalyst is a mesoporous material, the active component of CSP forms phosphate, metaphosphate, pyrophosphate and other phosphate structures on the surface of the support. The acid-base properties of the catalyst surface determine the activity of the catalyst. The acidity and alkalinity of the catalyst were characterized by CO2/NH3-TPD. It was found that P could effectively regulate the acid-base properties of the catalyst surface. The activity of Cs-P/ 纬 -Al 2O 3 catalyst was evaluated by a fixed bed reactor, and the influence of loading amount, carrier and calcination temperature on the catalytic activity was investigated. The results showed that 10%Cs-5%P/ 纬 -Al 2O 3 catalyst exhibited good catalytic activity after calcination at 550 鈩，

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