高效铁系变换催化剂的研制

发布时间：2018-06-07 00:22

本文选题：催化剂 + 共沉淀法　；参考：《山东理工大学》2015年硕士论文

【摘要】：铁铬系高(中)温变换催化剂具有较好的耐热性能、较高的机械强度、有一定的耐硫能力、寿命较长、原料廉价易得等特点,被广泛应用于高(中)温变换制氢装置。但该催化剂低温活性差,起活温度高,堆密度较大,耐沸水能力差等缺陷束缚了其发展。本文针对其缺陷开展研究,探索高效铁系变换催化剂的制备条件,考察了高效铁系变换催化剂的工艺性能,完成实验室小试,并对最优产品进行表征分析。本文选用共沉淀法,分步沉淀的加料方式制备催化剂。活性组分的原料采用硝酸盐,减少了催化剂制备中洗涤次数并降低了催化剂本体含硫量。沉淀剂选择弱碱,试验发现弱碱更有利于催化剂棒状晶型的形成,更有利于降低催化剂的堆密度。试验中主要考查了助剂铜含量、投料方式、反应温度、终点pH值、老化时间、干燥方式和焙烧温度对催化剂活性的影响。经微型固定床反应器测试得出最优制备条件为:投料方式:分步沉淀法,沉淀剂:NaHCO3,反应温度为:75℃,终点pH值:10,老化时间:120min,用烘箱120℃干燥3h,焙烧温度:350℃。试验中对不同铜助剂的含量和不同投料方式制备的催化剂进行X射线衍射、H2-TPR表征,对催化剂前驱体进行TG-DTG表征。结果表明:铜离子能进入氧化铁反尖晶石结构,与置换出的二价铁离子相互作用减低了催化剂的还原温度,从而使催化剂具有较好的低温活性;分步沉淀的投料方式使催化剂活性组分间分散度更好,活性高;焙烧温度低于300℃,氢氧化物分解不完全,高于400℃三氧化二铁晶相发生不可逆转化影响催化剂活性。最优制备条件下制备出的自制催化剂再经微型固定床反应器测试其适合的工艺条件,从水气比、空速、耐热能力以及抗沸水能力上对自制催化剂进行性能考察。试验得出:自制催化剂有很好的低温活性和耐热性,可以在低水气比、高空速条件下正常运转,最低水汽比可达0.8,最大空速可达9000h-1,并且耐沸水能力好。本文的研究适用于铁系高温变换催化剂的制备和生产,对进一步催化剂制备工艺优化和实验室中试有着一定的指导意义。
[Abstract]:The high (medium) temperature conversion catalyst of iron chromium system has good heat resistance, high mechanical strength, high sulfur tolerance, long life, cheap and easy to get raw materials, and is widely used in high temperature conversion hydrogen production plant. However, the catalyst has poor low temperature activity, high living temperature, large density of heap, and poor boiling water tolerance and other defects. In this paper, in view of its defects, the preparation conditions of high efficiency iron transformation catalyst are explored, the process performance of high efficiency iron system transformation catalyst is investigated, laboratory test is completed, and the optimal product is characterized. In this paper, the catalyst is prepared by coprecipitation method and step precipitation method. The raw material of active component is used in this paper. Nitrate reduces the washing times in the preparation of the catalyst and reduces the content of sulfur in the catalyst. The precipitant selects weak alkali. It is found that the weak base is more beneficial to the formation of the rod like crystal and is more conducive to the reduction of the density of the catalyst. In the test, the content of copper, the way of feeding, the reaction temperature, the end pH value and the aging time are mainly examined in the experiment. The effect of drying method and calcination temperature on the activity of the catalyst. The optimum preparation conditions were obtained by the micro fixed bed reactor test: the feeding method: step precipitation method, NaHCO3, the reaction temperature was 75, the end pH value: 10, the aging time: 120min, the drying 3H at 120 C and the calcination temperature: 350. X ray diffraction and H2-TPR characterization of the catalyst prepared by the amount and the different feeding methods show that the precursor of the catalyst is characterized by TG-DTG. The results show that the copper ions can enter the structure of the iron oxide anti spinel, and the interaction with the replacement of the two valence iron ions reduces the reduction temperature of the catalyst, thus making the catalyst with better low temperature activity; The feeding mode of step precipitation makes the activity of the catalyst with better dispersion and high activity, the calcination temperature is lower than 300, the decomposition of hydroxide is not complete, and the irreversible transformation of the crystal phase of ferric oxide is higher than 400 C, and the catalyst activity is influenced by the irreversible transformation of the crystal phase of ferric oxide. The prepared catalyst is then tested by the micro fixed bed reactor. The properties of the self-made catalyst are investigated from the ratio of water to gas, air velocity, heat resistance and boiling water. It is concluded that the self-made catalyst has good low temperature activity and heat resistance, it can operate normally at low water to gas ratio and high altitude, the minimum water vapor ratio can reach 0.8, the maximum airspeed can reach 9000h-1, and the boiling water resistance ability can be resisted. The study of this paper is suitable for the preparation and production of iron system high temperature transformation catalyst. It has certain guiding significance for the optimization of the preparation process of the catalyst and the laboratory test.
【学位授予单位】：山东理工大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：O643.36;TQ116.2

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