New Approach to Extend Durability of Sorbent Powders for Multicycle High Temperature CO2 Capture in Hydrogen

延长多循环高温二氧化碳捕集氢气吸附剂粉末耐久性的新方法

• 批准号: EP/J014702/1
• 负责人: Steven Milne
• 金额: $ 21.35万
• 依托单位: University of Leeds
• 依托单位国家: 英国
• 项目类别: Research Grant
• 财政年份: 2012
• 资助国家: 英国
• 起止时间: 2012 至 无数据
• 项目状态: 已结题
• 来源: https://gtr.ukri.org/projects?ref=EP%2FJ014702%2F1
• 关键词: New; Approach; Extend; Durability; Sorbent

Research into solid adsorbents for CO2 is motivated by their potential advantages over liquid amine, membrane or cryogenic separation techniques in mid-high temperature CO2 separation, for example, in hydrogen production via steam reforming/gasification of waste biomass where production yields are increased through the use of a sorbent powder such as CaO that chemically binds the CO2 from the mixed product stream and shifts the reaction thermodynamics to increase hydrogen output. There are also applications in large scale CO2 capture involving integration with fossil fuel fired power stations, and other industries.This materials engineering based proposal addresses the major problem facing utilisation of powder sorbents such as CaO for high temperature applications, including hydrogen production by sorbent enhanced steam reforming (SESR) of waste biomass. A decay in CO2 capture performance due to changes in the structure of the powder bed (densification) during regeneration at high temperatures prevents full exploitation of this promising technology in SESR and large scale CO2 capture applications. Significant powder densification occurs after heat-treatments at > 800 C to release CO2 and regenerate the sorbent. This leads to loss of porosity and sorbent surface area, causing a serious decay in CO2 capture performance. Developments in recent years, for example, adding refractory spacer particles are only successful for non-optimal regeneration conditions (e.g. < 850 C in inert atmospheres).The powders to be developed in this 18 month feasibility study will exploit a novel means of counteracting densification and loss of surface area, aiming to achieve regeneration at 950 C (much higher than for existing sorbents) in atmospheric conditions without significant decay in CO2 sorption capacity. An important advantage of the new powders is that a near-pure CO2 stream will be generated during regeneration at 950 C, producing output streams suited to integration with CO2 storage and/or utilisation programmes; this contrasts to the mixed gas streams generated at lower temperatures using existing materials. The new approach to the durability problem is to disperse ultrafine particles of partially stabilised zirconia (PSZ) in the sorbent matrix. The PSZ particles undergo a phase transition on cooling after regeneration which results in an increase in particle (crystallite) volume. Resulting strains generated in the surrounding, partially sintered, sorbent matrix will cause microcracks and secondary strain fields to develop which will open up pore channels for ingress of gasses. Loss of CO2 capture capacity in the subsequent sorption step will thus be mitigated, even for technologically favoured high regeneration temperatures (950 C), leading to increased multi-cycle sorbent efficiency, and increased hydrogen yield in SESR. The anti-densification mechanism will also be evaluated for an alternative CO2 sorbent, Na2ZrO3.

对CO2的固体吸附剂的研究是由它们在中高温CO2分离中相对于液体胺、膜或低温分离技术的潜在优势所激发的，例如，在通过蒸汽重整的氢气生产中，废弃生物质的气化，其中通过使用化学结合来自混合产物流的CO2并改变反应热力学的吸附剂粉末如CaO来提高产率以增加氢气产量。此外，还可以应用于大规模的CO2捕集，包括与化石燃料发电站和其他行业的集成。这一基于材料工程的提案解决了高温应用中使用粉末吸附剂（如CaO）所面临的主要问题，包括通过吸附剂增强蒸汽重整（SESR）废弃生物质制氢。由于高温再生过程中粉末床结构的变化（致密化）而导致的CO2捕获性能下降，阻碍了这项有前途的技术在SESR和大规模CO2捕获应用中的充分利用。在> 800 C的热处理以释放CO2并再生吸附剂后，发生显著的粉末致密化。这导致孔隙率和吸附剂表面积的损失，导致CO2捕获性能的严重衰减。近年来的发展，例如，添加耐火间隔颗粒仅在非最佳再生条件下成功（例如，在惰性气氛中< 850 ℃）。在这项为期18个月的可行性研究中开发的粉末将利用一种新的方法来抵消致密化和表面积损失，目的是在大气条件下在950 ℃（比现有吸附剂高得多）下实现再生，而CO2吸附能力没有显著衰减。新粉末的一个重要优点是，在950 ℃下再生期间将产生近纯的CO2流，产生适合与CO2储存和/或利用计划集成的输出流;这与使用现有材料在较低温度下产生的混合气流形成对比。解决耐久性问题的新方法是将部分稳定的氧化锆（PSZ）超细颗粒分散在吸附剂基质中。PSZ颗粒在再生后冷却时发生相变，导致颗粒（微晶）体积增加。在周围部分烧结的吸附剂基质中产生的应变将导致微裂纹和二次应变场的发展，这将打开用于气体进入的孔道。因此，即使在技术上有利的高再生温度（950 ℃）下，在随后的吸附步骤中CO2捕集能力的损失也将减轻，从而导致多循环吸附剂效率增加，以及SESR中氢产率增加。抗致密化机制也将被评估为替代CO2吸附剂，Na 2 ZrO 3。