纳米Li_2ZrO_3吸收剂原位移除CO_2强化水煤气变换反应制氢

采用浸渍法制备了在水煤气变换(WGS)反应中具有高催化活性的Ni/γ-Al2O3催化剂,使用柠檬酸法合成出高效CO2吸收剂Li2ZrO3纳米材料.在固定床微反应器上对WGS和吸附强化水煤气变换(SE-WGS)反应制氢过程进行了比较研究.前者只使用20%Ni/γ-Al2O3催化剂,而后者将20%Ni/γ-Al2O3催化剂与纳米Li2ZrO3吸收剂混合装填.结果表明,纳米Li2ZrO3具有比已报道的CO2吸收剂更快的吸收速率及优异的吸脱附循环稳定性,可应用于吸附强化过程,通过原位吸收WGS反应产生的CO2,使得反应超越化学平衡限制,直接制得高纯度H2.在823K,0.1MPa和H2O/CO=4的条件下,在SE-WGS过程一步制得纯度高于98%的H,验证了吸附强化反应进程制高纯氢的可行性.

Li2ZrO3 Nanoparticles as Absorbent for in-Situ Removal of CO2 in Water-Gas Shift Reaction to Enhance H2 Production

Ni/γ-Al2O3 catalyst with high activity in water-gas shift (WGS) reaction was prepared by an impregnation method,and nano-sized Li2ZrO3 absorbent with excellent CO2 capture properties was synthesized by a citrate sol-gel method.Two processes,WGS over 20% Ni/γ-Al2O3 catalyst alone and sorption-enhanced WGS (SE-WGS) over 20% Ni/γ-Al2O3 catalyst admixing with nano-sized Li2ZrO3 absorbent in a fixed-bed microreactor,towards the production of H2 were compared.The nano-sized Li2ZrO3 absorbent shows better CO2 capture properties than other CO2 absorbents reported so far in terms of uptake rate and reusability.Based on these excellent properties,the application of the developed Li2ZrO3 absorbent in sorption-enhanced reaction process (SERP) for the in-situ removal of CO2 produced from WGS leads to the equilibrium shift of the reaction to the production of H2 with high purity.The H2 purity higher than 98% can be achieved by SE-WGS at 823 K,a total pressure of 0.1MPa,and a H2O/CO molar ratio of 4,demonstrating the concept of SERP for H2 production.