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乙醇脱氢合成乙酸乙酯催化剂的研究
【作者】 赵树峰；
【导师】 菅盘铭；
【作者基本信息】 扬州大学 ， 工业催化， 2008， 硕士
【摘要】 以ZrOCl2为锆源,采用溶胶-凝胶法首先制备出Zr（OH）4凝胶,再将凝胶进行醇化处理,烘干和焙烧制得ZrO2纳米载体。以ZrO2为载体,采用浸渍法制备了负载型CuO/ZrO2催化剂。以凝胶Zr（OH）4粉末为前驱物,制备了掺杂型CuO-ZrO2催化剂。采用共沉淀法制备了共沉淀型催化剂CuO·ZrO2。以Cu和Zr的共沉淀物为前驱物,制备了Pd-CuO·ZrO2复合金属氧化物催化剂。通过XRD、N2吸附、TG-DCS、TEM、SEM和Raman对载体和催化剂进行表征。以乙醇氧化脱氢合成乙酸乙酯为探针反应,考察了不同制备方法对CuZrO系列催化剂的催化性能的影响。研究表明:制备的ZrO2载体具有较大的比表面积、孔容和均匀的孔径分布;在不同制备方法所得的样品中,共沉淀型CuO·ZrO2催化剂比表面积和孔体积是最大的;对于掺杂型催化剂CuO-ZrO2、共沉淀催化剂CuO·ZrO2而言,活性组分的加入可延迟ZrO2的相变,且掺杂型的延迟效果更为显著;对Pd-CuO·ZrO2研究表明Pd和Cu两种元素的加入可以极大的改变ZrO2的晶相结构,远比单金属Cu含量增加更有效。本文对制备的CuZrO系列催化剂催化性能进行了考察。发现CuZrO系列催化剂对乙醇的催化氧化具有较高的活性,CuO作为活性组分可以明显的提高乙酸乙酯的选择性。实验考察了反应温度、空气流速、催化剂焙烧温度、活性组分含量以及不同制备方法对催化剂催化性能的影响。催化剂活性变化规律为:共沉淀型>掺杂型>负载型。本文对催化反应进行了工艺条件优化,优化的工艺条件为:Cu含量为6%,550℃焙烧,反应温度为473 K,反应气流速30 mL/min。掺杂型CuO-ZrO2的活性处于负载型和共沉淀型之间,乙醇转化率为28%,乙酸乙酯选择性为83%;共沉淀型CuO·ZrO2活性最好,乙醇转化率为39%,乙酸乙酯选择性为88%。同时实验表明催化剂在反应过程中表现出了较好的稳定性。Pd-CuO·ZrO2催化剂活性评价表明:Pd的加入可以提高催化剂对乙醇的转化率性,但对于乙酸乙酯的选择性不利。
【Abstract】 Zr（OH）4 gel was prepared by sol-gel method from ZrOCl2 material. Then the the gel was alcoholized by ethanol, dried, and calclined to get ZrO2 nanometer scale particles. Supported catalysts CuO/ZrO2 were prepared by impregnation method. Doped CuO-ZrO2 catalysts were prepared that Cu（NO3）2 was supported on Zr（OH）4. CuO·ZrO2 catalysts were prepared by co-precipitated method. The catalyst Pd-CuO?ZrO2 was prepared that PdCl2 was supported on Cu（OH）2-Zr（OH）4. The catalysts were characterized by XRD、N2 adsorption-desorption、TG-DCS、TEM、SEM and Raman. Catalytic activities of the catalysts were investigated by dehydrogenation of ethanol to ethyl acetate as the probe reaction.The result of research show that ZrO2 which has higher surface area and pore volum、well-distributed pore is got; CuO·ZrO2 catalysts has the highest surface area and pore volum during the samples prepared by different ways; That the active constituent Cu was added into CuO-ZrO2 and CuO?·ZrO2 can put off the transition of ZrO2 from tetragonal crystal to monoclinic crystal and the delay of transition in doped CuO-ZrO2 catalysts is more evidence; The addition of Pd and Cu can change the crystal structure more than only Cu by increasing its content.Catalytic activities of the catalysts were investigated. The results indicate that the catalysts prepared by different ways have the catalytic activity by dehydrogenation of ethanol to ethyl acetate, the active constituent Cu can improve the selectivity of ethyl acetate. The influence of activity by different metal, reaction temperature, velocity of flow, temperature of calcination, content of metal and different methods of preparation was studied. The discipline of catalytic activity is: CuO?ZrO2>CuO-ZrO2>CuO/ZrO2. The process conditions were optimized as following: the content of Cu is 6%, the temperature of calcinations is 550℃, the reaction temperature is 473 K, the space velocity is 30 mL/min. The catalytic activity of CuO-ZrO2 is between the CuO·ZrO2 and CuO/ZrO2, the conversion of ethanol is 28% and the selectivity of ethanol to ethyl acetate is 83% is attained. The CuO?ZrO2 catalyst has the highest catalytic activity during the catalysts. The conversion of ethanol is 39% and the selectivity of ethanol to ethyl acetate is 88%. The results of stability tests indicated that the catalysts performed a well performance. The research of Pd-CuO?ZrO2 activity shows that the addition of Pd can increase the conversion of ethanol, but it is not good for the selectivity of ethanol to ethyl acetate.