超重力共沉淀法制备铜基甲醇合成催化剂及其性能表征

发布时间：2018-05-19 02:40

  本文选题：超重力 + 共沉淀　； 参考：《北京化工大学》2010年硕士论文

【摘要】： 甲醇是是C1化学的基础物质,它是精细化工重要的基础原料,主要用于制造甲醛、醋酸、氯甲烷、甲氨、硫酸二甲脂等有机产品,也是农药、医药的重要原料之一。近年来,能源危机的频繁爆发,以及环境污染的加剧,使人们对于新型清洁能源的需求越来越迫切。甲醇因其自身清洁、无毒、无污染的特性,自上世纪60年代来,吸引了越来越多的目光。经过深加工后,甲醇可以作为柴油、汽油的掺烧物质,其燃烧值高,可减少尾气污染。在我国这样一个能源消耗大国,开展新型甲醇合成催化剂的研究具有广阔的应用前景和深远的意义。 目前,工业上铜基催化剂一般采用共沉淀法制备,但是传统共沉淀反应在搅拌釜中进行,由于受到设备结构等因素的限制,为了达到微观结构的均匀混合,就必须以高能耗为代价,因此不利于工业生产。此外,由于产物不能及时移出反应体系,使得反应体系中的物质生成速率不均,反应时间相差较大,CuO／ZnO两组分相互分散度不高。由此生成的催化剂颗粒粗细不等,活性组分分布不均。 超重力技术的出现,能够很好的解决以上问题。它能实现反应物在反应体系内的瞬间微观均匀混合,制备催化剂时,反应成核区和晶体生长区是分开的,使晶体的生长区置于完全宏观混合区,制备出的催化剂组分分布均匀、粒度分布窄且晶型可控。它的出现为催化剂的制备提供了新的探索途径。 本文首次采用超重力反应技术制备铜基甲醇合成催化剂,并对其催化性能进行了表征与评价。在实验中,制备一系列不同Cu／Zn摩尔比的CuO／ZnO／Al2O3催化剂,并对催化剂制备过程中存在的各种影响因素进行了研究,采用XRD、TG-DSC、IR、BET、N2吸附、SEM等表征方法对催化剂前躯体、氧化物的物相组成、粒径、孔结构、表面形貌等进行了研究。结果表明,采用超重力共沉淀法所制备的CuO／ZnO／Al203催化剂与传统共沉淀法制备的催化剂相比,粒度更细化,比表面积更大,Cu、Zn两组分分散度更好。同时,采用CO+H2混合气在5.0MPa下进行甲醇合成活性测试。结果表明,超重力共沉淀法制备的催化剂在220℃-260℃的范围内均具有很高的活性。其中以摩尔比为n(Cu)／n(Zn)／n(Al)=4.5／4.5／1的催化剂活性最高,CO转化率达到35.3%。采用超重力共沉淀技术制备的催化剂,整体性能均优于传统共沉淀法,具有较好的工业应用前景。
[Abstract]:Methanol is the basic material of C1 chemistry. It is an important basic raw material of fine chemical industry. It is mainly used in the manufacture of organic products such as formaldehyde, acetic acid, chloromethane, methylamine, dimethyl sulfate and so on. It is also one of the important raw materials of pesticide and medicine. In recent years, with the frequent outbreak of energy crisis and the aggravation of environmental pollution, the demand for new clean energy is becoming more and more urgent. Methanol has attracted more and more attention since 1960s because of its clean, nontoxic and pollution-free characteristics. After deep processing, methanol can be used as a mixture of diesel oil and gasoline, its combustion value is high, and the tail gas pollution can be reduced. In a large energy consuming country such as China, the research of new methanol synthesis catalyst has broad application prospect and far-reaching significance. At present, coprecipitation method is generally used for coprecipitation of coprecipitation catalysts in industry, but the traditional coprecipitation reaction takes place in agitator. Due to the limitation of equipment structure and other factors, in order to achieve homogeneous mixing of microstructure, It must be at the expense of high energy consumption, so it is not conducive to industrial production. In addition, because the product can not be moved out of the reaction system in time, the formation rate of substances in the reaction system is uneven, and the reaction time is quite different. The dispersion of the two components is not high. The resulting catalyst has different particle sizes and uneven distribution of active components. The emergence of high-gravity technology, can solve the above problem very well. It can realize the instantaneous microscopic homogeneous mixing of reactants in the reaction system. When the catalyst is prepared, the nucleation region and the crystal growth region are separated, so that the crystal growth region is placed in the complete macroscopic mixing region, and the composition of the prepared catalyst is uniformly distributed. The grain size distribution is narrow and the crystal form is controllable. It provides a new approach for the preparation of catalysts. In this paper, the copper-based methanol synthesis catalyst was prepared by high gravity reaction for the first time, and its catalytic performance was characterized and evaluated. In the experiment, a series of CuO/ZnO/Al2O3 catalysts with different molar ratio of Cu/Zn were prepared, and the influencing factors during the preparation of the catalyst were studied. The phase composition of the precursor and oxide of the catalyst was characterized by XRDX TG-DSCIRN / BETN 2 adsorption method. The particle size, pore structure and surface morphology were studied. The results show that the CuO/ZnO/Al203 catalyst prepared by hypergravity coprecipitation method has smaller particle size and higher specific surface area than that prepared by conventional coprecipitation method, and the dispersion of the two components is better than that prepared by conventional coprecipitation method. At the same time, the activity of methanol synthesis was tested by CO H 2 mixture under 5.0MPa. The results show that the catalysts prepared by hypergravity coprecipitation have high activity in the range of 220 鈩，

本文编号：1908377