| 生物质超临界水制氢研究进展 |
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| 引用本文： | 徐功迅,陈伟,方真.生物质超临界水制氢研究进展[J].农业工程学报,2023,39(7):24-35. |
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| 作者姓名： | 徐功迅 陈伟 方真 |
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| 作者单位： | 南京农业大学工学院,南京 210031 |
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| 基金项目： | 国家自然科学基金面上项目（21878161）;南京农业大学高层次人才引进项目（68Q-0603） |
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| 摘 要： | 生物质超临界水制氢（supercritical water gasification,SCWG）以超临界水为介质通过热化学方式将生物质中的有机物转化为氢气等能源气体。相较于传统制氢方式,SCWG过程具有反应速度快、氢气选择性好、副产物少等优点,是一种高效、经济、清洁的生物质处理技术。该研究主要围绕SCWG过程中的影响因素进行系统地分析,介绍了超临界水特殊的物理化学性质,详细阐述了生物质主要成分如纤维素、半纤维素和木质素在SCWG过程中的反应机理,以及试验装置、原料类型和浓度、反应温度、停留时间、压力等工艺因素对SCWG的影响。研究发现纤维素占比较高的作物气化效果更好,低浓度的进料有利于气化效率和碳气化效率的提升,提高装置升温速率、适当增加反应温度和停留时间能够增加氢气产率,过大的压力会形成"溶剂笼"效应降低氢气产量。对不同类型反应系统研究表明,间歇式反应装置虽然结构简单、操作方便但也存在物料与催化剂混合不均匀、不能实现连续化生产而不适用于工业化推广,连续式反应装置虽面领着堵塞等问题,但具有性能好、效益高的优点,是工业化推广的发展方向。对SCWG主要应用的催化剂进行讨论发现,均相催化剂虽然具有催化效果但具有较强腐蚀性,非均相催化剂因其具有高催化活性、易回收、稳定性好等优点更适用于大规模SCWG生产过程,同时还研究了金属催化剂酸度在催化过程中的影响,发现酸度越高在SCWG过程中积碳会越明显,通过添加Cu、Ce、Co、La等合适的第二金属作为促剂可以改变催化剂性能,增加催化剂使用寿命,提高氢气选择性。未来应针对SCWG的试验装置、高效催化剂及经济性分析等核心技术开展研究,加速SCWG的工业化推广,实现经济、安全、绿色、高效的氢能供给。该研究期望加深对生物质SCWG理解,为日后研究提供理论指导。
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| 关 键 词： | 生物质 氢气 催化剂 超临界水 |
| 收稿时间： | 2023/1/11 0:00:00 |
| 修稿时间： | 2023/2/15 0:00:00 |
Research progress of supercritical water hydrogen production from biomass |
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| XU Gongxun,CHEN Wei,FANG Zhen.Research progress of supercritical water hydrogen production from biomass[J].Transactions of the Chinese Society of Agricultural Engineering,2023,39(7):24-35. |
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| Authors: | XU Gongxun CHEN Wei FANG Zhen |
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| Institution: | College of Engineering, Nanjing Agricultural University, Nanjing 210031, China |
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| Abstract: | Green, safe, and reliable clean energy is ever increasing under the "double carbon" goal. Among them, the waste biomass can be converted into green fuel, particularly with the application of many thermochemical and biochemical technologies. Supercritical Water Gasification (SCWG) can be a promising potential to convert the organic matter in the biomass into hydrogen using supercritical water as a medium. The feedstock can be used as a resource for biomass and the waste. SCWG process shares the fast reaction speed, excellent hydrogen selectivity, and fewer by-products, compared with traditional hydrogen production. In addition, water as the reactant in the SCWG process can avoid high energy consumption during drying, and thus reduce the cost. Previous systematic analysis has been made on the SCWG influence factors. In this review, the special physical and chemical properties of supercritical water were introduced to expound the main components (such as cellulose, hemicellulose, and lignin biomass) in the SCWG process reaction, and the experimental device, reaction temperature, residence time, and pressure in the influence factors. It was found that the batch reactor was suitable for the phase behavior and reaction mechanism, due to the simple structure and strong applicability of raw materials. By contrast, the continuous reaction device was used to more accurately control the experimental parameters, and then to realize the continuous commercial production, thus suitable for the parameter research. The hydrogen yield was improved to increase the heating rate of the device during operation, the reaction temperature, and residence time, but to reduce the feed concentration within a certain range. However, there was the complicated influence of pressure on the hydrogen yield. The solvent cage was often used under high pressure, leading to the reduction of the decomposition reaction rate unsuitable for the production of hydrogen. It was necessary to select the appropriate pressure, according to the actual situation. The homogeneous and heterogeneous catalysts were utilized in the SCWG. Specifically, the homogeneous catalyst performed a better catalytic effect on the water gas conversion was reaction, but the strong corrosion was caused the equipment to clog. The heterogeneous catalyst presented high catalytic activity, easy recovery, and excellent stability, more suitable for large-scale SCWG production. At the same time, there were some influences of the acidity of the metal catalyst in the catalytic process. The strong acidity of the catalyst accelerated the formation of carbon deposition, resulting in the catalyst deactivation. Appropriate secondary metals were added, such as Ce, La, and Ru. The performance of the catalyst was accelerated to increase the service life of catalyst for the better hydrogen selectivity. Future research can be focused on the equipment with corrosion resistance and salt deposition resistance, or constantly optimizing operating parameters, while the deactivation mechanism of catalysts, even to optimize the number of catalysts, and the catalysts with high activity and reusable. The existing technical barriers and development prospects of SCWG were analyzed to combine with the current technical development of SCWG. The finding can also provide theoretical guidance for the biomass SCWG in the future. |
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| Keywords: | biomass hydrogen catalysts supercritical water |
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