Production of high purity hydrogen from biomass/wood by catalyst-enhanced and reaction-integrated supercritical water gasification

氢(H2)是未来的燃料，是最清洁的燃料，在燃烧过程中空气污染物零排放。其需求持续增长，特别是在炼油、氨生产和燃料电池行业。目前，氢气主要由不可再生化石燃料(天然气)在高温(800-1 000摄氏度)下通过蒸汽重整转化而生产，生产成本较高，约为所用碳氢化合物成本的5倍。化石燃料是不可再生的，价格昂贵，化石燃料的使用会排放二氧化硫、氮氧化物和温室气体(二氧化碳)，严重破坏全球环境。因此，利用生物质(可再生能源)生产氢气是一种非常有前景的方法，因为它是一种成本效益高、环境友好的工艺，二氧化碳净排放量为零。据介绍，该项目旨在开发一种新型的催化剂增强型和反应集成超临界水气化(CERI-SCWG)工艺，用于在低得多的温度(400-600°C)下利用生物质/木材能源(包括树皮、木屑、锯末和纸浆厂固体废物)生产高纯度氢气。从环境和经济的角度来看，加拿大拥有世界上最丰富的木材生物质能源资源，开发这样一种生产氢气的技术将具有重要的战略意义。在传统的生物质/煤水蒸气气化过程中，整个反应是高度吸热和平衡受限的。为了实现碳的高转化率，需要较高的温度(800-1,200°C)，这导致了高能源消耗和高生产成本。超临界水(SCW)具有独特的溶剂化和传输性，特别是能够溶解通常不溶于液态水或水蒸气的物质，有利于气化反应。如果使用超临界水而不是水蒸气，生物质可以在更低的温度下高效转化为氢气。该项目的另一个创新之处是，通过使用催化剂和二氧化碳吸附剂，进一步从动力学和热力学上促进气化反应。

Hydrogen (H2), the fuel of the future, is the cleanest fuel with zero emission of air-pollutants during combustion. Its demand is continuously growing especially in the oil refining, ammonia production and fuel cells industries. Currently, H2 is produced mainly from conversion of non-renewable fossil fuels (natural gas) by steam reforming at high temperatures (800-1,000°C) with a high production cost, approximately 5 times the cost of the hydrocarbon used. Fossil fuels are non-renewable, expensive and the use of fossil fuels is seriously damaging to the global environment with emissions of SO2, NOx and the greenhouse gas (CO2). Thus producing H2 from biomass (the renewable energy resource) is very promising, as a cost-effective and environmentally friendly process with zero net CO2 emission.     This project aims at developing a novel Catalyst-Enhanced and Reaction-Integrated Supercritical Water Gasification (CERI-SCWG) process for production of high purity H2 from biomass/wood energy resources (including wood barks, wood chips, sawdust and the solid waste from pulp mills) at much lower temperatures (400-600°C). To develop such a technology to produce H2 would be strategically significant for Canada which has the world's most abundant wood biomass energy resources, from both environmental and economic points of view. In a conventional biomass/coal steam gasification process, the overall reaction is highly endothermic and equilibrium limited. In order to achieve a high conversion of carbon, high temperature (800-1,200°C) is required, leading to high energy-consumption and hence high production cost. Supercritical water (SCW) has unique solvating and transport properties, and in particular has the ability to dissolve materials not normally soluble in liquid water or steam, which thus favor the gasification reactions. If using SCW instead of steam, efficient conversion of biomass to hydrogen under much lower temperature may be achievable. Another novelty of the project is to further boost the gasification reactions kinetically and thermodynamically by employing catalysts and CO2 adsorbents.