双功能氧化物催化剂的制备及甲醇催化反应性能研究

发布时间：2019-02-24 20:44

【摘要】：甲醇作为煤化工和石油化工的产品在化工生产中具有极其重要的应用,但是今年来由于甲醇生产过剩,所以将甲醇制备为下游高附加值化学品具有重要的研究意义。其中,甲醇选择性氧化可以用于制备一系列具有工业应用价值的化学产品。甲酸甲酯作为甲醇氧化的下游产品,具有重要的工业价值,不仅仅可以作为药物生产以及有机合成的中间体,同时可以用于生产多碳分子碳氢化合物。传统制备甲酸甲酯的方法需要多步反应,反应副产物较多,不利于后期的分离。因此,利用双功能催化剂通过一步反应将甲醇转化为具有高附加值的甲酸甲酯具有重要的经济意义。甲醇氧化反应一步制取甲酸甲酯的合成路线由于其独特的优点已经吸引了学术界和工业上的广泛关注。虽然目前利用甲醇选择性氧化法生产甲酸甲酯的工业化技术还远未成熟,但是利用该法可以直接一步制备甲酸甲酯,经济高效,其中,双功能催化剂的设计以及制备具有重要的意义。本文使用等体积浸渍法将V2O5负载在SiO2、γ-A12O3、ZrO2和TiO2等载体表面,通过催化剂对甲醇氧化反应性能的研究发现以Ti02为载体时催化剂的活性最高。之后,通过对催化剂制备过程中不同V205负载量和不同焙烧温度条件的研究,优化了催化剂制备的条件,并对催化剂进行了改性,同时采用XRD、FTIR、TPR、TPD和XPS等方法对催化剂的结构进行了表征,并采用固定床反应器对催化剂的性能进行了评价。利用Ti02作为载体制备了 V205负载量分别为1wt%、5wt%、10wt%、15wt%和20wt%的一系列催化剂,结果表明:焙烧温度为500℃,10wt%V2O5/TiO2催化剂对于甲醇氧化反应的活性最高。之后,通过对反应条件的优化,表明在催化剂装填量为0.10 g,氧气流量为20 mL/min、氮气流量为20 mL/min,190 ℃的反应条件下,甲醇转化率可以达到44.94%,同时,甲酸甲酯的选择性和收率分别为61.01%和27.42%。最后测试了 10wt%V2O5/TiO2催化剂的稳定性,在持续催化反应80小时后,甲醇转化率和甲酸甲酯的选择性均只略有下降,这说明该催化剂对于甲醇氧化反应具备一定的稳定性。之后,本文研究了不同助剂对于催化剂改性的效果。分别添加MgO、La203、CeO2、CoO、CuO、ZrO2、Y2O3、Mo03 对 Ti02载体改性制备出复合载体后,制备了一系列改性的10wt%V2O5/TiO2催化剂。结果表明,Zr02助剂对催化剂的活性具有最好的改进效果。之后,优化了 Ti02-ZrO2复合载体的制备条件,当ZrO2添加量为10wt%,通过等体积浸渍法,在500℃下焙烧所制备的复合载体催化剂对甲醇氧化反应具有最高活性,其甲醇转化率可以达到50.34%,甲酸甲酯的选择性和收率为61.77%和31.10%。
[Abstract]:Methanol, as a product of coal chemical industry and petrochemical industry, has very important applications in chemical production. However, because of the excess production of methanol this year, it is of great significance to study the preparation of methanol as a high value-added chemical downstream. Among them, methanol selective oxidation can be used to prepare a series of chemical products with industrial application value. Methyl formate, as a downstream product of methanol oxidation, has important industrial value, not only as an intermediate in drug production and organic synthesis, but also in the production of multi-carbon hydrocarbons. The traditional method for the preparation of methyl formate requires multi-step reaction, and the byproducts of the reaction are many, which is not conducive to the later separation of methyl formate. Therefore, the conversion of methanol to methyl formate with high added value by one step reaction with bifunctional catalyst has important economic significance. The synthesis of methyl formate by one step methanol oxidation has attracted much attention in academia and industry because of its unique advantages. Although the industrial technology for the production of methyl formate by selective oxidation of methanol is still far from mature, the method can be used to produce methyl formate directly in one step, which is economical and efficient. The design and preparation of bifunctional catalysts are of great significance. In this paper, V2O5 was supported on the surface of SiO2, 纬 -A12O3ZrO2 and TiO2 by the method of equal volume impregnation. It was found that the activity of the catalyst was the highest when Ti02 was used as the carrier for methanol oxidation. After that, the conditions of catalyst preparation were optimized by studying the different loading amount of V205 and different calcination temperature during the preparation of catalyst, and the catalyst was modified, and XRD,FTIR,TPR, was used at the same time. The structure of the catalyst was characterized by TPD and XPS, and the performance of the catalyst was evaluated by fixed-bed reactor. A series of catalysts with V205 loading amount of 1 wtand 5 wtand 10wt% and 20wt% were prepared by using Ti02 as the carrier. The results showed that the calcination temperature was 500 鈩，

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