镍基整体式催化剂及其耦合重整净化生物质粗燃气性能研究

GIEC OpenIR > 中国科学院广州能源研究所

	镍基整体式催化剂及其耦合重整净化生物质粗燃气性能研究
其他题名	Ni based monolithic catalyst coupled reforming biomass fuel gas
	王晨光
导师	马隆龙
	2009-05-27
学位授予单位	中国科学院广州能源研究所
学位授予地点	广州能源研究所
学位名称	博士
学位专业	热能工程
关键词	镍基整体式催化剂生物质燃气重整脉冲电晕
摘要	近年来，随着我国经济的飞速发展造成电力和燃料供应日趋紧张，能源问题已引起高度重视。生物质由于其产量巨大、可再生，被喻为循环利用的地表绿色煤炭，其大规模利用问题已引起全球的广泛关注。其中，生物质气化技术因原料适应性广、系统简单、效率高、环境友好、产物用途广泛而成为世界各国研究开发的热点。目前，生物质气化和合成燃料技术已经相当成熟。生物质粗燃气的深度净化和品质提升已经成为制约生物质高端利用的瓶颈。商业水蒸气重整镍催化剂在生物质气化实际条件下重整净化粗燃气，会由于严重积碳而快速失活，与实际应用存在较大距离。为提高镍催化剂的稳定性并降低成本，本文在对镍基整体式催化剂研究的基础上，采用分步浸渍法制备了高稳NiO-MgO固溶体整体式催化剂，考察了重整条件对催化剂结构与稳定性的影响。在NiO-MgO固溶体整体式催化剂上，对生物质气化粗燃气的重整反应特性以及合成气的组分调变工艺进行了研究，并结合脉冲电晕对生物质重整净化进行了研究，得到了如下结论： 1．镍基整体式催化剂能较好的重整净化生物质粗燃气。在750oC条件下，粗燃气中的CH4和CO2转化率均能达到90%左右而合成气的H2/CO值均能保持在1.0左右，108 h连续重整反应过程中，反应器内未观测到压力变化，表明整体式催化剂的直通结构能够有效的避免催化剂表面的积碳引起的压力升高。连续反应过程中生物质粗燃气中的CH4和CO2转化率均保持在90%左右，表明催化剂具有较好稳定性。NiO-MgO固溶体整体式催化剂对生物质粗燃气也具有良好的重整净化效果，在750oC条件下，CH4转化率能达到95%以上而H2/CO值较镍基催化剂能提高到1.2左右，可以作为合成液体燃料的理想气源。60 h连续重整实验也表明了该催化剂具有良好的反应活性、稳定性和抗积碳性能。两种催化剂均能使生物质焦油模型化合物萘的转化率达到99%以上。两种催化剂均表现出了良好的焦油裂解性能。 2．采用临氧重整可以有效地提高反应效率，改善催化剂反应特性，提高CH4 的转化率至92%以上，同时提高了合成气中H2、CO的含量，并能够提高H2/CO值，使其达到1.1左右。O2 的加入提高了重整反应对粗燃气中焦油的净化能力，特别是对干重整条件下难于转化的高浓度物种和苯的含氧衍生物的有较高的转化率，焦油转化率达到99%以上。连续60 h的临氧和干重整实验显示，临氧条件下催化剂表现出了更好催化活性和稳定性，出口合成气的H2/CO值更高，更适合于合成液体燃料，O2的加入有助于提高催化剂的稳定性和活性。热重分析结果表明，O2含量的变化直接影响着催化剂表面积碳量和积碳物种，其中在O2/fuel为0.127时，催化剂表现出较好的抗积碳性能。水蒸汽重整不但可以显著提升生物质粗燃气的H2/CO值，并在1-5之间任意调变，也对提高生物质粗燃气中CH4的转化率也有较大帮助，这是由于H2O分子能够在重整过程中裂解产生较多活性氧化基团，提高重整效率。连续60 h的水蒸汽和干重整对照试验表明，水蒸汽重整可以有效提高反应稳定性和反应效率，并有效抑制催化剂表面积碳的发生。脉冲电晕-催化耦合重整采用高压高频放电使生物质粗燃气形成等离子体，后进行催化重整能够起到调节出口合成气体组成的效果，使之更适宜应用到液体燃料的合成。在较高放电频率时，原料气中的CH4、CO2的转化率、出口气的H2/CO值及H2 的选择性都有所提高，耦合重整能有效消除生物质粗燃气中的焦油。反应温度升高时，原料气中的CH4、CO2转化率也会随之升高，H2的选择性也会随温度升高而增加。但出口合成气的H2/CO值随温度的升高有所降低。脉冲电晕-催化耦合重整生物质粗燃气，能减轻催化剂表面活性金属的烧结情况。有效降低催化剂表面的积碳。 4．重整炉的传热是影响到催化剂效果好坏的重要因素，采用外加热方法能够保证催化剂在适当的温度进行重整净化。重整炉的设计应当能保证催化剂温度的均匀。重整炉前后压差实验表明，NiO-MgO固溶体整体式催化剂由于其直通结构的存在能够有效的避免催化床层压力升高过快。催化剂对生物质粗燃气有着明显的调变作用。气化过程中所产生的大量灰分沉积在管路中是导致重整炉压力升高的主要原因。
其他摘要	With the rapid develop of economy recently, power and fuel supply problem has been more and more serious, more attention is paid on energy problem. Of all the sources of renewable energy, biomass is the unique renewable source of carbon and named as green coal. Biomass to liquid technology is one of the most promising routine for the liquid fuel which can replace fossil fuel. Production of synthesis gas is the key step. In this article , high stable NiO-MgO solid solution monolithic catalyst was used to produce synthesis gas. It is very important to the production of carbon neutral fuels, solve the shortage problem of energy and rapid development of economy Biomass gasification and liquid fuel synthesis technologies are mature. Biomass fuel gas deeply cleaning and quality promotion are the bottleneck of the utilization of biomass. Commercial steam reforming Ni-based catalysts will rapidly lost their activity in real biomass gasification conditions because of carbon deposition. In order to promote the stability and reduce cost. In the present work, highly stable NiO-MgO solid solution monolithic catalyst was prepared by two step impregnation. The effect of preparation conditions on the catalysts structure and performance was investigated. The performance of different reforming conditions were also investigated. Biomass fuel gas reforming character and synthesis gas adjust were also studies. Plasma-catalytic reforming of biomass fuel gas was also investigated. The results obtained are listed below: 1.Ni-based monolithic catalyst can effectively reforming biomass fuel gas. The conversion of CH4 and CO2 are 90% under 750oC, H2/CO ratio was also kept at 1.0. In 108 hours reforming test, no pressure change was detected, catalyst showed good anti-carbon and pressure drop abilities because of the straight structure. In life test, conversion of CH4 and CO2 were kept at 90% which means the catalyst has high activity and good stability. NiO-MgO solid solution monolithic catalyst has excellent reforming activity and high stability. Conversion of CH4 can be higher than 95% at 750oC and H2/CO ratio was promoted to 1.2. 60 hours life test shows that NiO-MgO solid solution monolithic catalyst has excellent reforming activity, stability and anti-carbon deposition ability. Tar model compound naphthalene was completely converted to gas and lighter compounds over both catalysts. Two catalysts showed good tar elimination ability. 2.Partial oxidation reforming can effectively promote the reaction efficiency, CH4 conversion and H2, CO content in synthesis gas. It can also promote the H2/CO ratio to 1.1. The addition of O2 raised the tar elimination ability of the catalyst, especially the high concentration species and derivative of benzene which were difficult to convert in dry reforming. 60 hours life tests of partial oxidation reforming and dry reforming showed that catalyst in partial oxidation reforming had higher activity and stability, H2/CO ratio in outlet synthesis gas over partial oxidation reforming was higher than dry reforming. Synthesis gas produced by partial oxidation reforming is more suitable for liquid fuel synthesis. The addition of O2 will promote the stability and activity of the catalyst. TG results showed that O2 content change will change the carbon content and species on the surface of the catalyst. When O2/fuel reached 0.127, catalyst showed excellent anti-carbon deposition ability. Steam reforming can promote the H2/CO ratio and adjust it between 1-5. The addition of steam can also promote the conversion of CH4 in biomass fuel gas, which is caused by active oxide produced by H2O cracking during reforming. 60 hours life test showed that steam reforming can effective promote the stability and reforming efficiency, steam reforming can also prevent carbon deposition on the surface of the catalyst. 3.High voltage plasma excite biomass fuel gas molecules and then use catalytic reforming at 750oC to adjust gas components in outlet synthesis gas can promote the quality of synthesis gas make it more suitable for liquid fuel synthesis. Experiments with different frequency show that higher frequency will promote CH4, CO2 conversion, H2/CO ratio and H2 selectivity. Plasma-catalyt coupled reforming can eliminate tar in biomass fuel gas effectively. Higher reaction temperature will produce higher conversion of CH4 and CO2, it can also promote the selectivity of H2.XRD patterns show that plasma-catalyt coupled reforming can effectively prevent the catalyst from sintering and carbon deposition on the surface of the catalyst. 4. Heat transfer is the main effect of catalyst performance, a suitable burner can produce enough power to the reformer. The design of reformer should pay more attention on heat transfer to the catalyst. Pressure test results showed that NiO-MgO solid solution monolithic catalyst can avoid pressure raise rapidly because of its special structure. NiO-MgO solid solution catalysts can adjust biomass fuel gas. Plenty of ash is the main reason of pressure raise in reformer.
页数	160
语种	中文
文献类型	学位论文
条目标识符	http://ir.giec.ac.cn/handle/344007/5834
专题	中国科学院广州能源研究所
推荐引用方式 GB/T 7714	王晨光. 镍基整体式催化剂及其耦合重整净化生物质粗燃气性能研究[D]. 广州能源研究所. 中国科学院广州能源研究所,2009.

条目包含的文件		下载所有文件
文件名称/大小	文献类型	版本类型	开放类型	使用许可
200618014924012王晨光_p（30571KB）			开放获取	CC BY-NC-SA	浏览下载