| 有序介孔三氧化二锰负载PdPt合金:一种高效的甲烷催化燃烧催化剂 |
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| 引用本文： | 徐鹏,吴志星,邓积光,刘雨溪,谢少华,郭广生,戴洪兴. 有序介孔三氧化二锰负载PdPt合金:一种高效的甲烷催化燃烧催化剂[J]. 催化学报, 2017, 38(1): 92-105. DOI: 10.1016/S1872-2067(16)62567-6 |
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| 作者姓名： | 徐鹏 吴志星 邓积光 刘雨溪 谢少华 郭广生 戴洪兴 |
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| 作者单位： | 绿色催化与分离北京市重点实验室,区域大气复合污染防治北京市重点实验室,先进功能材料教育部重点实验室,催化化学与纳米科学实验室,北京工业大学环境与能源工程学院化学化工系,北京100124 |
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| 基金项目： | 教育部博士点项目基金，国家自然科学基金，国家高技术研究发展计划，北京市高校创新团队建设推进计划基金，科学研究基地建设-科技创新平台-国家材料研究基地建设基金. This work was supported by the Ph.D. Program Foundation of Ministry of Education of China，the NNSF of China，National High Technology Research and Development Program，Foundation on the Creative Research Team Con-struction Promotion Project of Beijing Municipal Institutions |
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| 摘 要： | 甲烷作为一种清洁廉价的碳氢能源,广泛应用于运输业和其它工业领域.但是其本身是一种比二氧化碳导致全球变暖效应更强的温室气体,而且甲烷直接燃烧会产生其它污染物,比如一氧化碳、氮氧化物、未充分燃烧的碳氢化合物等.因此有必要开展有关甲烷催化燃烧的研究工作,以大幅度降低起燃温度,提高燃烧效率,有效地减少污染副产物的产生.由于具有较好的低温催化活性,Pd基催化剂常用于甲烷的催化燃烧.但是Pd基催化剂也存在一些亟需解决的问题,比如在催化燃烧过程中活性相结构不稳定.PdO通常被认为是碳氢化合物催化氧化中的活性相,但是在高温下PdO分解为Pd,导致催化活性下降.PdO遇到含水或硫的化合物时会生成惰性的Pd(OH)2或稳定的硫化物,造成活性物种的流失,从而降低催化剂的性能.如果在材料中添加另一种贵金属Pt,使之与Pd一起形成贵金属合金,则可提高其低温催化燃烧的活性,增加Pd基催化剂的热稳定性以及抗水和抗硫能力.另一方面,过渡金属氧化物价格便宜,热稳定性以及抗硫性较好,也常作为甲烷燃烧的催化剂.其中三氧化二锰由于具有可变的氧化态以及较好的储氧能力受到了广泛关注.本课题组采用KIT-6作为硬模板,先合成具有有序介孔结构的Mn2O3(meso-Mn2O3)纳米催化剂,然后通过聚乙烯醇(PVA)保护的液相共还原法分别制备meso-Mn2O3担载Pd,Pt及PdPt合金的纳米催化剂(x(PdyPt)/meso-Mn2O3;x=(0.10-1.50)wt%;Pd/Pt摩尔比(y)=4.9-5.1).XRD结果表明,合成的meso-Mn2O3具有立方相晶体结构.其BET比表面积为106 m2/g.由TEM照片可观察到粒径范围为2.1?2.8 nm的贵金属纳米颗粒均匀分散在meso-Mn2O3表面.通过XPS分析可知,结合能在529.6和531.2 eV的峰可分别归属于晶格氧(Olat)和表面吸附氧(Oads).Pd0和Pd2+以及Pt0和Pt2+也均可通过曲线拟合后进行分峰确定.XPS定量分析结果表明,样品的Oads/Olat摩尔比有如下顺序:1.41(Pd5.1Pt)/meso-Mn2O3(0.77)>1.40Pd/meso-Mn2O3(0.69)>0.72(Pd5.1Pt)/meso-Mn2O3(0.65)>1.42Pt/meso-Mn2O3(0.63)>0.07(Pd4.9Pt)/meso-Mn2O3(0.53)>0.07(Pd4.9Pt)/bulk-Mn2O3(0.52)>meso-Mn2O3(0.45),这与其催化活性的顺序一相致.该结果表明,高的吸附氧物种浓度有利于甲烷催化燃烧.负载Pd,Pt或PdPt以后的样品的表面吸附氧物种浓度显著提高,催化活性最好的1.41(Pd5.1Pt)/meso-Mn2O3样品具有最高的吸附氧物种浓度.负载PdPt合金可有效提高催化剂对甲烷燃烧的催化活性.1.41(Pd5.1Pt)/meso-Mn2O3催化剂的活性最好:在空速为20000 mL/(g.h)的条件下,甲烷燃烧的T10%,T50%和T90%分别为265,345和425oC.此外,还考察了引入一定量的SO2,CO2,H2O和NO对甲烷在1.41(Pd5.1Pt)/meso-Mn2O3催化剂上氧化反应的影响,发现引入少量的Pt可提高催化剂抗SO2,CO2和H2O的能力,但是NO对甲烷燃烧的还原效应也不可忽视.基于催化剂物化性质的表征结果和活性数据,我们认为1.41(Pd5.1Pt)/meso-Mn2O3优异的催化性能与其拥有高质量的三维有序多孔结构、高的吸附氧物种浓度、优良的低温还原性以及Pd-Pt合金与meso-Mn2O3载体之间的强相互作用有关.
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| 关 键 词： | 有序介孔三氧化二锰 PdPt合金纳米颗粒 负载贵金属催化剂 金属-载体强相互作用 甲烷燃烧 |
| 收稿时间： | 2016-08-31 |
Catalytic performance enhancement by alloying Pd with Pt on ordered mesoporous manganese oxide for methane combustion |
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| Peng Xu,Zhixing Wu,Jiguang Deng,Yuxi Liu,Shaohua Xie,Guangsheng Guo,Hongxing Dai. Catalytic performance enhancement by alloying Pd with Pt on ordered mesoporous manganese oxide for methane combustion[J]. Chinese Journal of Catalysis, 2017, 38(1): 92-105. DOI: 10.1016/S1872-2067(16)62567-6 |
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| Authors: | Peng Xu Zhixing Wu Jiguang Deng Yuxi Liu Shaohua Xie Guangsheng Guo Hongxing Dai |
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| Affiliation: | Beijing Key Laboratory for Green Catalysis and Separation, Key Laboratory of Beijing on Regional Air Pollution Control, Key Laboratory of Advanced Functional Materials, Education Ministry of China, and Laboratory of Catalysis Chemistry and Nanoscience, Department of Chemistry and Chemical Engineering, College of Environmental and Energy Engineering, Beijing University of Technology, Beijing 100124, China |
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| Abstract: | Ordered mesoporous Mn2O3 (meso-Mn2O3) and meso-Mn2O3-supported Pd, Pt, and Pd-Pt alloy x(PdyPt)/meso-Mn2O3;x = (0.10-1.50) wt%; Pd/Pt molar ratio (y) = 4.9-5.1 nanocatalysts were prepared using KIT-6-templated and poly(vinyl alcohol)-protected reduction methods, respectively. The meso-Mn2O3 had a high surface area, i.e., 106 m2/g, and a cubic crystal structure. Noble-metal nanoparticles (NPs) of size 2.1-2.8 nm were uniformly dispersed on the meso-Mn2O3 surfaces. Al-loying Pd with Pt enhanced the catalytic activity in methane combustion; 1.41(Pd5.1Pt)/meso-Mn2O3 gave the best performance;T10%,T50%, andT90% (the temperatures required for achieving methane conversions of 10%, 50%, and 90%) were 265, 345, and 425 ℃, respectively, at a space velocity of 20000 mL/(g.h). The effects of SO2, CO2, H2O, and NO on methane combustion over 1.41(Pd5.1Pt)/meso-Mn2O3 were also examined. We conclude that the good catalytic performance of 1.41(Pd5.1Pt)/meso-Mn2O3 is associated with its high-quality porous structure, high adsorbed oxy-gen species concentration, good low-temperature reducibility, and strong interactions between Pd-Pt alloy NPs and the meso-Mn2O3 support. |
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| Keywords: | Ordered mesoporous manganese oxide Pd-Pt alloy nanoparticle Supported noble metal catalyst Strong metal-support interaction Methane combustion |
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