Masuda Taichi, Ikesaka Naoki, Muranaka Yosuke, Tanabe Katsuaki
Department of Chemical Engineering, Kyoto University Nishikyo Kyoto 615-8510 Japan
RSC Adv. 2023 Oct 16;13(43):30306-30328. doi: 10.1039/d3ra05367a. eCollection 2023 Oct 11.
Hydrogen production from biomass, a renewable resource, has been attracting attention in recent years. We conduct a detailed process design for cellulose-derived hydrogen production glucose using supercritical water gasification technology. Gasification of biomass in supercritical water offers advantages over conventional biomass conversion methods, including high gasification efficiency, elevated hydrogen molar fractions, and the minimization of drying process for wet biomass. In the process design, a continuous tank reactor is employed because the reaction in the glucose production process involves solids, and using a tube-type reactor may clog the reactor with solids. In the glucose separation process, glucose and levulinic acid, which cannot be separated by boiling point difference, are separated by using an extraction column. In the hydrogen separation process, the hydrogen purity, which could not be sufficiently increased with a single pressure swing adsorption (PSA) process, is increased to the target value by employing two sets of PSA columns. The overall utility cost is significantly reduced by $0.020/mol-H through heat integration. Our economic evaluation for this process results in a deficit of $0.015/mol-H, as a price to be paid by the human for renewable hydrogen production from biomass at the present stage. By simply adopting the reported experimental condition, our process contains a large amount of water and sulfuric acid, which requires an enormous cost for the neutralizer, drying utility, and extractant. To improve the economic performance of the process, it is necessary to consider the reaction of cellulose solution at a higher concentration to reduce the burden of glucose separation. In addition, the effective use of the wasted hydrogen with a purity of about 95 vol% from the second PSA column may also improve the process economics. Whilst, the required energy cost for hydrogen production for our process is calculated to be significantly lower than those for other various representative hydrogen production methods: 0.37 (0.44) times less than that of steam reforming of methane with (without) CO capture, 0.15 times less than that of the water electrolysis by the electric power system, and 0.073 times less than that of electrolysis of water by wind power. This result implies the practical potential of our cellulose-based green hydrogen production scheme.
生物质作为一种可再生资源，其制氢近年来备受关注。我们利用超临界水气化技术对纤维素衍生葡萄糖制氢进行了详细的工艺设计。生物质在超临界水中气化相较于传统生物质转化方法具有诸多优势，包括高气化效率、较高的氢气摩尔分数以及湿生物质干燥过程的最小化。在工艺设计中，采用连续釜式反应器，因为葡萄糖生产过程中的反应涉及固体，使用管式反应器可能会被固体堵塞。在葡萄糖分离过程中，利用萃取塔分离沸点相近无法通过沸点差异分离的葡萄糖和乙酰丙酸。在氢气分离过程中，单级变压吸附（PSA）工艺无法充分提高氢气纯度，通过采用两组PSA柱将氢气纯度提高到目标值。通过热集成，总公用工程成本显著降低，每摩尔氢气降低0.020美元。我们对该工艺的经济评估结果显示，每摩尔氢气亏损0.015美元，这是现阶段人类为生物质可再生制氢所付出的代价。仅采用已报道的实验条件时，我们的工艺含有大量水和硫酸，这需要用于中和剂、干燥公用工程和萃取剂方面的巨大成本投入。为提高该工艺的经济性能，有必要考虑在更高浓度下进行纤维素溶液反应以减轻葡萄糖分离的负担。此外，有效利用来自第二组PSA柱的纯度约为95体积%的废氢也可能改善工艺经济性。同时，计算得出我们工艺的制氢所需能源成本显著低于其他各种代表性制氢方法：比有（无）CO捕集的甲烷蒸汽重整制氢低0.37（0.44）倍，比电力系统水电解制氢低0.15倍，比风力发电水电解制氢低0.073倍。这一结果表明了我们基于纤维素的绿色制氢方案具有实际应用潜力。
