双模纳米多孔铜的脱合金法制备及其催化性能的研究

发布时间：2018-07-15 13:46

【摘要】：利用脱合金法制备纳米多孔金属,是一种较简单且能有效得到具有高内表面积、高孔隙率和较均匀孔径的纳米孔结构的方法。此外,纳米多孔金属不仅保留了金属材料的高导热率、高导电率等优异性能,还因其纳米级的特征尺寸而具备了块体金属所没有的性质(如高催化能力)。因此,纳米多孔金属及脱合金方法近年来引起了越来越多的关注。目前可用脱合金化法来制备纳米多孔金属(如纳米多孔金、铂、钯、银、铜等)、纳米多孔合金(如:纳米多孔金铂、铂钯等)等材料。虽然贵重金属(合金)具有优异的性能,但对性质活泼的铜的研究不仅具有科学研究价值还能为工业上合理利用铜资源提供指导。本文主要通过球磨-冷压-烧结、冷压-烧结的方法制备Al-Cu(NaCl)合金并通过水浴的方法除去NaCl模板从而得到多孔的Al-Cu合金前驱体,通过脱合金方法最终得到具有双模式孔结构的铜/铜氧化物。一是选取Al_(67)Cu_(33)为研究对象,用球磨法均匀混合Al、Cu、NaCl粉末,常温下压制成粉坯后进行烧结(本文称其为冷压-烧结),研究NaCl的加入量、烧结温度和烧结时间对纳米多孔铜/铜氧化物结构及组成的影响,并将其脱合金产物应用于催化降解甲基橙和超级电容器性能的测试;二是采用转速较低的研磨仪混合不同比例的Al、Cu、NaCl粉末,通过冷压-烧结来制备NaCl比例不同的Al-Cu(NaCl)合金,再通过去盐-脱合金法获得双模式纳米多孔铜/铜氧化物。根据纳米多孔铜/铜氧化物超声催化降解甲基橙的效率确定Al-Cu合金的最优加盐量。然后使用化学镀金的方法,以脱合金产物为载体在其表面镀金,制备负载型金催化剂。最后根据其催化氧化CO的活性温度探究工艺的可行性并确定最佳工艺参数,初步探究了负载型纳米金催化剂催化CO氧化的原理。用冷压-烧结制备加盐的Al-Cu合金,通过探究实验发现Al-Cu合金中最佳加盐量为5 wt.%。究其原因是脱合金产物中形成两种不同尺寸范围的孔道,两种孔道作用不同:较大孔道(~1000nm)加快扩散,小孔道(~40nm)有利于提高比表面积进而提供更多化学反应活性位点,这种拥有双模式结构的纳米多孔材料比只有单一尺度范围孔道的纳米多孔材料具有更好的催化效率。脱合金一般产物为Cu/Cu2O,但产物为Cu/CuO/Cu2O时,催化效率最高。通过置换的方式在纳米多孔铜/铜氧化物表面再沉积贵金属Au颗粒,主要研究了负载型纳米金对催化剂整体催化氧化CO反应中的效果,包括CO的转化率达到百分之百时所处的温度,以及在相同温度下不同催化剂对CO的转化率,并分析了负载型催化剂催化CO氧化的原理。研究发现,负载Au纳米颗粒的纳米多孔铜/铜氧化物对CO氧化的催化效率比未负载的有大幅度的提高(可提升27%)。脱合金产物基体表面沉积微量的金,由于Au与载体之间的协同效应使催化剂对CO的催化氧化具有比未负载Au产物更高的催化活性。
[Abstract]:The preparation of nano-porous metal by dealloying method is a simple and effective method to obtain nano-pore structure with high internal surface area, high porosity and uniform pore size. In addition, nano-porous metals not only retain the excellent properties of metal materials such as high thermal conductivity and high conductivity, but also possess the properties (such as high catalytic ability) of bulk metals because of their characteristic size. Therefore, nano-porous metals and dealloying methods have attracted more and more attention in recent years. At present, nano-porous metals (such as nano-porous gold, platinum, palladium, silver, copper, etc.) and nano-porous alloys (such as nano-porous gold platinum, platinum-palladium, etc.) and nano-porous alloys (such as nano-porous gold platinum, platinum-palladium, etc.) can be prepared by dealloying method. Although precious metals (alloys) have excellent properties, the study of active copper has not only scientific research value, but also can provide guidance for the rational utilization of copper resources in industry. In this paper, Al-Cu (NaCl) alloy was prepared by ball milling, cold pressing sintering, and the porous Al-Cu alloy precursor was obtained by removing NaCl template by water bath. Finally, copper / copper oxide with double mode pore structure was obtained by dealloying method. One is to select Al _ (67) Cu _ (33) as the object of study, mix the Al _ (67) Cu _ (33) powder uniformly with the ball milling method, press it into powder billet at room temperature, and then sintered (this paper calls it "cold pressing sintering"), and study the adding amount of NaCl. The effects of sintering temperature and sintering time on the structure and composition of nano-porous copper / copper oxide were investigated. The dealloying products were used to test the catalytic degradation of methyl orange and supercapacitor. Secondly, Al-Cu (NaCl) alloys with different NaCl ratios were prepared by cold pressing and sintering with a low rotating speed grinder, and double mode porous copper / copper oxides were obtained by desalination and desalination. According to the ultrasonic degradation efficiency of nano-porous copper / copper oxide, the optimum salt addition of Al-Cu alloy was determined. Then the supported gold catalyst was prepared by electroless gold plating. Finally, according to the feasibility of the catalytic oxidation of CO and the optimum process parameters, the principle of the supported nanometer gold catalyst for CO oxidation was preliminarily explored. Al-Cu alloy was prepared by cold pressing and sintering. The optimum salt addition in Al-Cu alloy was found to be 5 wt. The reason is that two kinds of pores with different sizes are formed in the dealloyed products. The two channels act differently: the larger channels (1000 nm) accelerate the diffusion, and the small channels (40 nm) increase the specific surface area and provide more chemical reactive sites. This kind of nano-porous material with two-mode structure has better catalytic efficiency than the nano-porous material with only a single pore size range. The general product of dealloying is Cu / Cu _ 2O, but the catalytic efficiency is the highest when the product is Cu / Cu _ 2O / Cu _ 2O. The noble metal au particles were redeposited on the surface of nano-porous copper / copper oxide by displacement. The effect of supported nano-gold on the overall catalytic oxidation of CO on the catalyst was studied. It includes the temperature at which the conversion of CO reaches 100% and the conversion of CO by different catalysts at the same temperature. The principle of catalytic oxidation of CO with supported catalyst is analyzed. It was found that the catalytic efficiency of au nanoparticles supported on nano-porous copper / copper oxides for CO oxidation was much higher than that of unloaded copper nanoparticles (up to 27%). Due to the synergistic effect between au and the support, the catalyst has higher catalytic activity for CO oxidation than the unsupported au product, due to the trace amount of gold deposited on the substrate surface of the dealloyed product.
【学位授予单位】：济南大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：O643.36

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