铜基和锌基二甲醚水蒸气重整制氢催化剂

发布时间：2018-01-23 12:54

本文关键词： 制氢二甲醚水蒸气重整产物选择性铜基催化剂锌基催化剂　出处：《天津大学》2016年博士论文　论文类型：学位论文

【摘要】：日益增长的化石能源消耗不可避免的导致了能源短缺和环境污染问题,因此,探索和使用新型清洁能源变得越来越重要。作为一种清洁的可再生能源,氢气符合未来能源的发展趋势。二甲醚水蒸气重整制氢是有效的制氢手段之一,其核心技术是催化剂的开发。目前用于该反应的催化剂的研究重点在于如何提高催化剂的低温选择性、稳定性和高温活性。针对以上问题,本文以γ-Al_2O_3为固体酸,分别与铜基金属催化剂和锌基金属氧化物催化剂构成复合催化剂,对金属催化剂和金属氧化物催化剂做了研究。调变催化剂的组成,采用BET、XRD、H2-TPR、XAFS、TPD-MS-CH3OH、in-situ FTIR、XPS等技术对催化剂做了详细表征,并对催化剂的结构和性能进行了关联。采用共沉淀法制备了CuAlZn60-xNixO催化剂,考察Ni的掺杂量对催化剂的影响。活性和稳定性测试结果表明,Ni的最佳掺杂量为0.2%,Ni的加入使DME转化率和氢气收率均有所提高,催化剂稳定性增强。表征结果显示,Ni的掺杂可以提高铜物种的分散度,降低其还原温度,从而提高催化剂的活性。采用共沉淀法制备Ga掺杂的GDZ催化剂,考察镓的掺杂对ZnO催化剂的影响。适量Ga掺杂入ZnO的晶格中,可以提高催化剂的电导率,当Ga:Zn为1:9时,GDZ催化剂具有最高的导电率,与之对应的Zn9Ga1O/γ-Al_2O_3催化剂具有最高的DME转化率(95.4%)和最高的H2收率(95%)。本文研究结果表明,DME SR反应在GDZ催化剂上为n型反应,CO2的生成是DME SR反应在GDZ/γ-Al_2O_3催化剂上的控制步骤,从HCOO-到CO2的反应为n型反应。采用共沉淀法制备Zn9Ga1O载体,负载不同量的CuO组分组成重整催化剂,考察铜的负载量对催化剂结构和催化性能的影响。活性测试表明,负载量为10%CuO的催化剂表现出最好的催化活性,其表观活化能为110 kJ·mol-1。表征结果表明,随着氧化铜负载量的增加,铜的分散度从12.0%下降到7.0%,10CuO/Zn9Ga1O的铜比表面积最大,为5.72 m2·g-1。反应后催化剂中大量存在的Cu+有利于DME SR反应的发生和CO选择性的降低。铜的负载有利于甲醇分子的活化和转化,甲醇在x CuO/Zn9Ga1O催化剂上的转化为逐步脱氢,最后以二氧化碳形式脱附的过程。共沉淀法制备不同Ce/Zr比的CexZr_(1-x)O载体,负载不同量的Zn9Ga1O活性组分用于二甲醚水蒸气重整制氢,考察预还原温度,Zn9Ga1O的负载量和不同的CexZr_(1-x)O载体对催化剂活性的影响。活性测试表明,460°C为合适的预还原温度,x Zn9Ga1O/Ce0.8Zr0.2O催化剂活性明显优于载体Ce0.8Zr0.2O和活性组分Zn9Ga1O的活性,20Zn9Ga1O/Ce0.8Zr0.2O催化剂的二甲醚转化率最高。20Zn9Ga1O/CexZr_(1-x)O催化剂低温活性差别较大,催化剂20Zn9Ga1O/Ce0.8Zr0.2O活性最好。低温下,20Zn9Ga1O/CexZr_(1-x)O催化剂的氢气较好,高温下催化剂促进了生成CO副反应的发生,使氢气收率下降,CO选择性升高。表征结果显示,适量Zr的掺杂,使载体中表面氧的还原能力增强,表面氧物种流动性增加。甲醇在20Zn9Ga1O/Cex Zr_(1-x)O表面易形成甲氧基,氢气和二氧化碳易脱附。20Zn9Ga1O/CexZr_(1-x)O催化剂之间氢气和二氧化碳的脱附温度差异不大,因此20Zn9Ga1O/CexZr_(1-x)O催化剂的高温活性差异不大。
[Abstract]:The increasing consumption of fossil energy inevitably leads to energy shortage and environmental pollution problems, therefore, to explore and use of new clean energy becomes more and more important. As a kind of clean and renewable energy, hydrogen energy. With the future development trend of the two dimethyl ether steam reforming for hydrogen production is one of the effective means, its core technology is the catalyst the current research focus for development. The catalyst of this reaction is how to improve the selectivity of the catalyst at low temperature, high temperature stability and activity. In view of the above problems, this paper based on gamma -Al_2O_3 as solid acid, and copper based metal catalysts and metal oxide catalysts composed of zinc based composite catalyst of metal catalysts and metal oxide catalysts were studied. Composition, regulating catalyst by BET, XRD, H2-TPR, XAFS, TPD-MS-CH3OH, in-situ, FTIR, XPS and so on the catalyst technology Detailed characterization, structure and properties of catalyst were investigated. The CuAlZn60-xNixO catalysts were prepared by co precipitation, affect the effects of Ni doping amount on the catalyst activity and stability test. The results showed that the optimal doping amount of Ni is 0.2%, the addition of Ni to DME conversion and hydrogen yield were improved, the stability of the catalyst enhanced. The characterization results indicate that Ni doping can improve the dispersion of the copper species, reduce the reduction temperature, thereby increasing the catalytic activity of GDZ catalyst prepared by coprecipitation. Ga doping method, the effects of gallium doping on ZnO catalyst. The amount of Ga doped into the ZnO lattice, can improve the conductivity of the catalyst. When the Ga:Zn is 1:9, the GDZ catalyst has the highest conductivity of the Zn9Ga1O/ gamma -Al_2O_3 catalyst and the corresponding with the highest conversion rate of DME (95.4%) and the highest yield of H2 (95%). This paper studies The results show that the DME SR reaction on GDZ catalyst for the N reaction, the formation of CO2 is the control step DME SR reaction in GDZ/ gamma -Al_2O_3 catalyst, the reaction from HCOO- to CO2 for N type reaction. The preparation of Zn9Ga1O vector co precipitation method, CuO group load different amount of reforming catalyst composition, influence the effects of copper loading on the structure and catalytic performance of the catalyst. The activity test showed that the loading of 10%CuO catalyst showed the best catalytic activity, the apparent activation energy of 110 kJ show that the characterization of mol-1. with the increase of copper oxide loading, the dispersion degree of copper decreased from 12% to 7%, 10CuO/Zn9Ga1O the surface area of copper, for there are a lot of 5.72 M2 - g-1. catalyst after reaction of Cu+ and CO DME to reduce the incidence of selective SR reaction. The copper loaded with activation and transformation to methanol, methanol on X CuO/Zn9Ga1O catalyst To transform the stepwise dehydrogenation, finally to form carbon dioxide desorption process. The coprecipitation of different Ce/Zr ratio of CexZr_ (1-x) O carrier, Zn9Ga1O activity group load different amounts for two dimethyl ether steam reforming, the effects of pre reduction temperature, the loading of Zn9Ga1O and different CexZr_ (1-x) effect O supports on catalyst activity. Activity tests showed that 460 DEG C appropriate reduction temperature, the activity of X Zn9Ga1O/Ce0.8Zr0.2O catalyst was better than that of Ce0.8Zr0.2O carrier and active component of the activity of Zn9Ga1O, 20Zn9Ga1O/Ce0.8Zr0.2O catalyst two methyl ether the highest conversion rate of.20Zn9Ga1O/CexZr_ (1-x) O catalyst activity at low temperature difference is large, the best catalyst under low temperature 20Zn9Ga1O/Ce0.8Zr0.2O activity. 20Zn9Ga1O/CexZr_ (1-x) O catalyst, hydrogen is good, high temperature catalyst promoted the formation of CO reaction, the hydrogen yield decreased, the selectivity of CO Increased. The characterization results indicate that proper Zr doping increased the reduction ability of the surface oxygen carrier, surface oxygen species increased liquidity. Methanol in 20Zn9Ga1O/Cex Zr_ (1-x) O easily formed on the surface of methoxy, hydrogen and carbon dioxide to desorption of.20Zn9Ga1O/CexZr_ (1-x) with temperature difference between hydrogen and carbon dioxide removal of O catalyst therefore, 20Zn9Ga1O/CexZr_ (1-x) is high activity difference of O catalyst.

【学位授予单位】：天津大学
【学位级别】：博士
【学位授予年份】：2016
【分类号】：O643.36;TQ116.2

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