二甲醚部分氧化重整制氢催化剂优化的研究

发布时间：2018-06-19 15:17

本文选题：二甲醚 + 部分氧化　；参考：《辽宁工业大学》2015年硕士论文

【摘要】：二甲醚（DME）稳定，无毒，无腐蚀性，且具有较高的含氢量，是一种理想的氢载体。二甲醚的生产技术已逐步成熟，所以由二甲醚制氢有其可行性。前人的研究多集中于催化剂的筛选与反应条件的优化上，针对二甲醚部分氧化重整制氢催化剂的优化的工作却比较少。本文在针对二甲醚部分氧化重整制氢反应过程与催化剂作用研究基础上，对该反应的催化剂体系中的重整催化剂进行优化。主要以碱土金属对重整催化剂Ni/Al2O3进行改性，并考察了不同Ce:Zr比例的Ni/Ce-Zr-Ox催化剂和Ni基介孔载体催化剂的反应性能，比较了催化剂优化效果。以碱土金属（Mg、Ca、Sr、Ba）对重整催化剂Ni/Al2O3进行改性， MgO的加入会提高NiAl2O4的结晶度与稳定性，在催化剂还原过程中生成的Ni含量较少，且趋于纳米粒子，因而活性高，稳定性好，催化剂性能优于未改性的催化剂；而Ca、Sr、Ba改性的催化剂没有促进NiAl2O4的结晶，在低温下即被还原，其性能不如未改性的。 Mg加入量改性的研究表明，7.5%MgO、10%MgO改性均能够提高Ni/Al2O3的催化活性，但7.5%MgO改性的催化剂中NiAl2O4稳定性适宜，，能够在还原时形成适量的Ni活性中心，所以7.5%MgO改性的催化剂效果更明显。不同Ce:Zr比例的Ni/Ce-Zr-Ox催化剂的反应性能均优于Ni/Al2O3的反应性能，其中Ce:Zr比为1:4的催化剂效果最优，因为在Ce:Zr=1:4的载体中形成结晶度适宜的铈锆固溶体，在固溶体的影响下NiO颗粒较小，同时铈锆固溶体因其独特的氧化还原性质提高活性组分NiO的分散度，使得催化剂活性及稳定性均有所提升。三种Ni基介孔载体催化剂（Ni/介孔Al2O3、介孔Ni-7.5%MgO-Al2O3与Ni/介孔7.5%MgO-Al2O3）都在较低温度下，即会有较大量Ni被还原出来而形成多原子活性中心，无论是氢气收率还是含碳产物选择性均不如Ni/Al2O3催化剂的催化性能。最后对比发现，7.5%MgO改性的Ni/Al2O3催化剂优于的Ni/Ce-Zr-Ox(Ce:Zr=1:4)催化剂。
[Abstract]:DMEs are stable, non-toxic, non-corrosive, and have high hydrogen content, which is an ideal hydrogen carrier. The production technology of dimethyl ether has matured gradually, so it is feasible to produce hydrogen from dimethyl ether. Previous studies have focused on the selection of catalysts and optimization of reaction conditions, but less work has been done on the optimization of catalysts for partial oxidative reforming of dimethyl ether for hydrogen production. Based on the study of the reaction process of partial oxidative reforming of dimethyl ether for hydrogen production and the reaction of catalyst, the reforming catalyst in the catalyst system of this reaction was optimized. The Ni / Al _ 2O _ 3 reforming catalyst was modified by alkali earth metal, and the reaction performance of Ni / Ce-Zr-Ox catalyst with different ce: Zr ratio and Ni / Ce-Zr-Ox catalyst was investigated, and the optimum performance of the catalyst was compared. The Ni / Al _ 2O _ 3 reforming catalyst was modified by alkaline earth metal (MgO). The addition of MgO can improve the crystallinity and stability of NiAl _ 2O _ 4. The Ni content produced in the reduction process of the catalyst is less and tends to nanometer particles, so it has high activity and good stability. The catalytic performance of the catalyst was better than that of the unmodified catalyst, while the catalyst modified by CaOSR-Ba did not promote the crystallization of NiAl _ 2O _ 4 and was reduced at low temperature. The results of mg addition showed that the modified Ni / Al _ 2O _ 3 catalyst could improve the catalytic activity of Ni / Al _ 2O _ 3, but the Ni _ (Al _ 2O _ 4) _ 4 catalyst modified by 7.5MgO was suitable for the stability of Ni _ (Al _ 2O _ 4) and formed a proper amount of Ni _ 2O _ 3 active center during the reduction. So the effect of 7.5 MgO modified catalyst is more obvious. The reaction performance of Ni / Ce-Zr-Ox catalyst with different ce: Zr ratio is better than that of Ni / Al _ 2O _ 3. The catalyst with ce: Zr ratio of 1:4 is the best, because the cerium-zirconium solid solution with suitable crystallinity is formed in the support of ce: Zr-1: 4, and the nio particle is smaller under the influence of solid solution. At the same time, the cerium zirconium solid solution increased the dispersion of nio because of its unique redox property, which improved the activity and stability of the catalyst. The Ni / Al _ 2O _ 3, Ni _ (7.5) Al _ 2O _ 3 and Ni / Al _ 2O _ 3 / Ni / Ni / Al _ 2O _ 3 mesoporous catalysts were reduced to form polyatomic active centers at lower temperatures, and the Ni / Al _ 2O _ 3 / Ni / Al _ 2O _ 3 mesoporous catalysts were reduced to form polyatomic active centers. Both hydrogen yield and selectivity of carbon-containing products were not as good as that of Ni / Al _ 2O _ 3 catalyst. Finally, it is found that the Ni / Al _ 2O _ 3 catalyst modified by 7.5MgO is superior to the Ni / Ce-Zr-Ox-Cew: Zr1: 4 catalyst.
【学位授予单位】：辽宁工业大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TQ116.2;O643.36

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