【作者】 宋辉；

【导师】 余江龙；

【作者基本信息】 沈阳航空工业学院 ， 航空宇航推进理论与工程， 2009， 硕士

【摘要】 天然气传统燃烧利用方式不仅造成严重的环境污染,而且能源利用效率低。催化燃烧技术作为一种环境友好且燃烧效率高的能源利用方式越来越受到重视。本文从甲烷燃烧催化剂载体和过渡金属元素Fe、Cu、Ni分别与CeO₂形成的Ce_1-xM_xO_y（M=Fe、Cu、Ni）复合氧化物的催化活性两方面详细研究了过渡金属元素对甲烷催化燃烧过程的影响。本文采用X射线衍射（XRD）、扫描电子显微镜（SEM）和激光粒度分析等多种分析方法对富含Al2O3、SiO2和Fe2O3的粉煤灰的特性进行了详细的分析,包括:粒度分级测试、磁性分析、成分分析、微观形貌分析和晶相结构分析。并考察了粉煤灰对甲烷燃烧的催化作用,研究表明粉煤灰具有孔隙结构且活性高,有一定的催化活性。并进一步以粉煤灰为载体过渡金属氧化物Fe2O3为活性组分制备了负载型催化剂,详细研究了粉煤灰的颗粒粒度、磁性和活性组分负载浓度等因素对甲烷催化燃烧性能的影响。结果表明:具有磁性且粒径小的粉煤灰颗粒负载大浓度的活性组分时对甲烷燃烧具有最佳的催化活性。作者采用共沉淀法结合微波干燥技术将过渡金属元素Fe、Cu、Ni的氧化物与CeO₂混合,制备了Ce_1-xM_xO_y（M=Fe、Cu、Ni）系列复合氧化物,并采用热重和差热分析方法,对所制备的复合氧化物的前驱体进行了详细的分析。通过甲烷燃烧催化活性测试,考察了过渡金属元素取代值x对Ce_1-xM_xO_y（M=Fe、Cu、Ni）复合氧化物甲烷催化燃烧活性的影响,结果表明:过渡金属元素Fe和Ni与CeO₂形成的Ce_1-xFe_xO_y和Ce_1-xNi_xO_y复合氧化物的甲烷燃烧催化活性显著提高,取代值x是影响复合氧化物甲烷燃烧催化活性的重要因素,对于Ce_1-xFe_xO_y复合氧化物,取代值x为0.3时,即Ce0.7Fe0.3Oy催化活性最好,而在Ce_1-xNi_xO_y复合氧化物中,x为0.5时,即Ce0.5Ni0.5Oy催化活性最好,Cu引入CeO₂晶格形成的Ce1-xCuxOy复合氧化物催化活性并未得到明显改善。同时,在Ce_1-xM_xO_y（M=Fe、Cu、Ni）复合氧化物中掺杂稀土元素La,研究了La掺杂对复合氧化物甲烷催化燃烧性能的影响。研究表明:将少量稀土元素La掺杂于Ce_1-xM_xO_y（M=Fe、Cu）复合氧化物中,有助于其催化活性的提高,但掺杂过高会使其催化活性下降,在Ce_1-xNi_xO_y复合氧化物中掺杂La催化活性均显著下降。更多还原

【Abstract】 Conventional combustion of natural gas （i.e. methane） not only causes serious air pollution, but also has low utilization efficiency. Catalytic combustion of methane is becoming attractive in recent years due to the high combustion efficiency and less pollutant emission and therefore is more environmentally friendly. In this thesis, the effects of trasition metals on the catalytic combustion of methane have been studied systematically with respect to both the catalyst support and the catalytic reactivity of Ce_1-xM_xO_y （M=Fe、Cu、Ni） of the composite metal oxides by adding trasition metals, i.e., Fe、Cu、Ni into cerium oxides.The author analyzed the properties of coal fly ash including size distribution, magnetic separation, chemical composition, crystal structure and microstructure and morphology by means of X-ray Diffraction （XRD）, Scanning Electronic Microscope （SEM） and Laser Particle Size Analyser, etc. The catalytic reactivity of coal ash during methane combustion was assessed. The results indicated that coal ash, due to its porous structure and some active components, may catalyse the comubstion of methane under the present expeimental conditions. A series of surpported catalysts were prepared using coal ash as the support with transition metal, i.e., ferric oxide, as the main active component and the effects of coal ash particle size, magnetic separation and the loading level of active catalytic components were carefully studied. The results demonstrated that catalysts supported on coal ash with smaller particle size or on magnetic fraction of the coal ash with a higher loading level of active components showed better catalytic reactivity during methane combustion.By using co-precipitation in combination with microwave drying and calcination, composite metal oxides Ce_1-xM_xO_y （M=Fe、Cu、Ni） were prepared by introducing transition metals such as Fe、Cu and Ni into ceria oxide and the precursors of composite oxides were analyzed in details by using a thermogravimetry with differential thermal analysis （TGA-DTA）. The effect of substitution ratio ,x, of trasition metals on the catalysts reactivity during methane combustion was investigated.The results showed that the catalytic reactivity of methane combustion increased dramatically through the use of Ce_1-xFe_xO_y and Ce_1-xNi_xO_y composite oxides which were formed from above mentioned method. The substitution ratio ,x, was an important factor influencing the catalyst reactivity during methane combustion. Under the present conditions, the optimum substitution ratio is 0.3, i.e. the compostion of Ce0.7Fe0.3Oy has the highest catalytic reactivity. However, for Ni, the optimum value of x was 0.5, i.e. Ce0.5Ni0.5Oy showed better catalytic reactivity. The addition of Cu seemed not significantly influence the catalytic reactivity of the cerium oxide. The effect of doping La on the catalytic reactivity of the composite oxide Ce_1-xM_xO_y （M=Fe、Cu、Ni） was also carefully studied. The results showed that La may be effective to improve the performance of the composite oxide Ce_1-xM_xO_y （M=Fe、Cu） when the loading level is low, further increase in the doping level will lead to the decrease of the catalytic reactivity of the catalyst.However,doping Ce_1-xNi_xO_y composite oxides with La decreases their catalytic reactivity dramatically.更多还原