Pr和Sm改性的镍基和铜基催化剂在甲醇水蒸气重整制氢中的研究

发布时间：2018-02-05 02:24

本文关键词： 甲醇水蒸气重整制氢 Ni基催化剂 Cu基催化剂 Pr Sm　出处：《昆明理工大学》2017年硕士论文　论文类型：学位论文

【摘要】：甲醇是最简单的醇类,来源广泛,含氢量高,含硫量低(5ppm)。因为甲醇不含C-C键,所以在甲醇水蒸气重整制氢(SMR)过程中所需反应温度低(200-350℃),产生的副产物少。甲醇水蒸气重整制氢能够为燃料电池提供高纯度低CO的氢气,被认为是极具应用前景的制氢技术。Ni能促进C-C键、O-H键和C-H键的断裂因此被应用于甲醇水蒸气重整制氢当中,但Ni基催化剂的催化反应需要的反应温度较高。Cu基催化剂因其高活性和对氢气的高选择性而被广泛的应用于甲醇水蒸气重整制氢,但是Cu的金属稳定性低,极易烧结致使催化剂失活,因此,选取Ni和Cu改性。本论文研究了稀土金属Pr和Sm负载到Ni基和Cu基催化剂当中对甲醇水蒸气重整制氢催化性能的影响,着重考察了稀土负载量对催化剂性能的影响,并且通过XRD、H2-TPR、XPS、Raman、TGA、O2-TPO、TEM和HAADF/STEM等表征手段深入研究了稀土金属对催化剂结构特性的影响与催化活性之间的相互关系。主要研究结果如下:(1)探究了 Pr负载到Ni/Al2O3催化剂上对催化活性的影响。采用等体积浸渍法制备了不同Pr负载量的Ni/Al2O3催化剂,结果表明,Pr负载量低于12.5%时,催化剂的在甲醇水蒸气重整制氢中催化活性得到提高,Pr的最佳负载量为10%;Pr使得Ni/Al203催化剂当中NiO从NiAl204中脱离,催化剂还原后形成了Pr6O11@Ni/NiO超级结构,得到更多的活性金属Ni,提高了催化剂的催化性能;Ni/Al2O3催化剂在本试验条件中仅有少量活性炭形成,Pr的存在可以减少催化剂表面的活性炭并且提高催化剂的催化稳定性。(2)考察了 Sm的添加对Cu/Al203催化剂催化活性的影响。将Sm负载到Cu/A1203催化剂中,催化剂在甲醇水蒸气重整制氢中的催化活性随Sm负载量增加而降低;Sm的添加抑制了 Cu/Al2O3中CuO的还原,不利于CuO的形成;Sm使得Cu在催化剂表面形成团聚,使得其颗粒增大,减少了 Cu的总表面积,使得催化剂催化活性显著降低。(3)研究了 Sm负载量与Ni/Al203催化剂催化活性的关系。Sm的负载量在5-10%之间时,催化活性随Sm负载量增加而提升,最佳负载量为10%;Sm与Pr一样,也能够使NiO从NiAl204中脱离,但是稀土金属负载量达到12.5%以上时,负载Sm的Ni/Al203催化剂催化性能低于负载相同含量Pr的Ni/Al203催化剂;浸渍时间为12h时所得催化剂催化性能高于浸渍时间为Oh和24h的催化剂,干燥时间为24h时,催化剂性能高于干燥时间为4h的催化剂。
[Abstract]:Methanol is one of the most simple alcohols, wide source, high hydrogen content, low sulfur content (5ppm). Because methanol does not contain C-C key, so in the methanol steam reforming (SMR) reaction temperature required in the process of low (200-350 DEG C), byproducts. The steam reforming of methanol and hydrogen can provide the hydrogen with high purity and low CO for fuel cell is considered to be promising hydrogen production technology of.Ni can promote the C-C bond cleavage of the O-H bond and C-H bond are therefore used in methanol steam reforming for hydrogen production, but the required reaction temperature catalytic reaction of Ni based catalysts with high.Cu catalyst for its high activity and the hydrogen selectivity and is widely used in the methanol steam reforming for hydrogen production, but the metal stability of Cu is low, easy to cause the sintering deactivation of the catalyst, therefore, selected Ni and Cu modified. This paper studies the rare earth metals Pr and Sm load to the Ni based and Cu based catalysts Effect of methanol steam reforming for hydrogen production by catalytic performance, focuses on the influence of loading on the catalytic performance of rare earth, and through XRD, H2-TPR, XPS, Raman, TGA, O2-TPO, TEM and HAADF/STEM were used to study the relationship between the effect of rare earth metal on properties of the catalyst structure and catalytic activity. The main results are as follows: (1) to explore the Pr load to the Ni/Al2O3 catalyst on the catalytic activity. The effects of the Ni/Al2O3 catalysts with different Pr loadings prepared by impregnation method. The results show that the Pr load is lower than 12.5%, the catalyst in methanol steam reforming for hydrogen production in catalytic activity was improved and the optimal loading Pr 10%; Pr NiO NiAl204 from the Ni/Al203 catalyst in the catalyst formed from Pr6O11@Ni/NiO super structure, obtained more active metal Ni, improved catalyst The catalytic performance of Ni/Al2O3 catalyst; only a small amount of activated carbon is formed in the condition of this experiment, the presence of Pr can reduce the activated carbon on the catalyst surface and improve the catalytic stability of the catalyst. (2) investigated the effect of Sm addition on the catalytic activity of Cu/Al203 catalyst. The load will Sm to the Cu/A1203 catalyst, the catalyst in the methanol steam reforming catalyst the activity of hydrogen production with the loading amount of Sm increased; the addition of Sm inhibited the reduction of Cu/Al2O3 in CuO, is not conducive to the formation of CuO; Sm makes Cu agglomeration on the catalyst surface, the particle size, reduce the total surface area of Cu, the catalytic activity decreased significantly. (3) the research on load the amount of.Sm Sm load Ni/Al203 catalyst catalytic activity and the catalytic activity in 5-10%, as Sm loading increased, the best load was 10%; Sm and Pr, also can make NiO from The NiAl204 detachment, but rare earth metal loading reached more than 12.5%, the catalytic properties of Sm supported Ni/Al203 is lower than that of the catalyst Ni/Al203 the same content of Pr; the soaking time was 12h higher than that of the catalytic performance of catalyst impregnation time as catalyst Oh and 24h, the drying time is 24h, the catalyst performance is higher than that of dry time is 4H the catalyst.

【学位授予单位】：昆明理工大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：O643.36;TQ116.2

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