Unmixed Steam Reforming of Liquid Fuels From Biomass and Waste for Hydrogen Production

纯蒸汽重整是一种很有前途的替代制氢工艺。它依靠镍基材料床的循环氧化和气流下二氧化碳吸附剂的同时再生来提供蒸汽重整反应所需的热量。当气流中断时，后者随后在燃料/蒸汽流动下发生。燃料/蒸汽步骤的排出气体的氢含量远高于单反应器等效的传统工艺，并且氧化的催化剂通过暴露于燃料的还原而再生。由于蒸汽重整过程中产生的碳随后在气流下燃烧，因此该过程对传统工艺所表现出的转换效率的逐渐损失不敏感。此外，在未混合蒸汽重整过程中，燃料中的硫在气流作用下也发生氧化，而不是不可逆地毒害重整催化剂。最重要的是，与传统工艺不同，这种工艺在小规模上是经济的，因此可以用于分布式发电。这些优势为这种新工艺应用于各种具有焦化倾向和/或硫含量的燃料开辟了机会，例如来自生物质或特定工业/运输废物的可燃液体混合物。当在重整炉中使用合适的co2吸附剂时，重整气中的干氢含量可达80%以上（使用甲烷燃料时可达90%以上）。在这种情况下，气流排出的大部分产生的CO2和N2分别离开反应器进入富h2的重整气，并且可以很容易地过滤和储存。在现已完成的GR/R50677/01项目中，我们展示了循环中涉及的各种反应进行的顺序，并且我们发现了该过程对焦化不敏感的明确证据。我们的结论是，某些发展将改进原来的过程。这些都列在目标中。

Unmixed steam reforming is a promising alternative process of hydrogen production. It relies on the cyclic oxidation of a bed of nickel-based material and on the simultaneous regeneration of a CO2-sorbent under airflow to provide the heat necessary for the steam reforming reaction. The latter occurs subsequently under a fuel/steam flow while the airflow is interrupted. The effluent gas of the fuel/steam step is much higher in hydrogen than the single reactor equivalent conventional process, and the oxidised catalyst is regenerated by reduction from exposure to the fuel. Because the carbon produced during the steam reforming step is subsequently burned under the airflow, the process is not sensitive to the gradual loss of conversion efficiency exhibited by the conventional process. Furthermore, in the unmixed steam reforming process, sulphur in the fuel is claimed to also undergo oxidation under the airflow rather than irreversibly poisoning the reforming catalyst. This process most importantly claimed to be economical at small scale, unlike the conventional process, and could thus be used in distributed power generation. These advantages open up opportunities for this novel process to apply to a whole range of fuels with coking tendencies and/or sulphur content, such as the combustible liquid mixtures derived from biomass or specific industrial / transportation waste. When using a suitable CO2-sorbent in the reformer, the dry hydrogen content in the reformate gas reaches above 80% (90+% when using on methane fuel). In this case, most of the produced CO2 and the N2 from the airflow effluent leave the reactor separately to the H2-rich reformate gas, and can potentially be easily filtered and stored. In the now completed GR/R50677/01 project, we showed the sequence via which the various reactions involved in the cycle proceeded, and we found clear evidence of the insensitivity of the process to coking. We concluded that certain developments would improve on the original process. These are listed in the objectives.