Evaluation of diamine-appended metal-organic frameworks for post-combustion CO2 capture by vacuum swing adsorption

• Published in: Separation and purification technology 2019-03, Vol.211, p.540-550
• Main Authors: Pai, Kasturi Nagesh, Baboolal, Johan D., Sharp, David A., Rajendran, Arvind
• Format: Article
• Language: English
• Subjects: CO2 capture; Metal-organic framework; Multi-objective optimization; Vacuum swing adsorption
• ISSN: 1383-5866; 1873-3794
• DOI: 10.1016/j.seppur.2018.10.015

•Diamine-doped metal-organic frameworks show reversible S-shaped CO2 isotherm.•Multi-objective optimization of VSA process for CO2 capture using diamine-doped MOFs.•mmen-Mn2: 17.6% lower energy compared to Zeolite13X for CO2 purity >95%, recovery >90%.•Zeolite 13X offers higher productivity compared to the MOFs.•Lower N2 capacity & stronger CO2 competition are reasons for lower energy consumption. Five different diamine-appended metal-organic frameworks (MOFs) that show a S-shaped CO2 isotherm are evaluated for post-combustion CO2 capture from dry flue gas using a vacuum swing adsorption process. A comprehensive simulation and optimization study using a multi-objective genetic algorithm is performed. The optimization to maximize CO2 purity and recovery showed a key link between the feed temperature, evacuation pressure and process performance. The MOFs that achieve a target CO2 purity ⩾95% and recovery ⩾90%, namely, mmen-Mn2(dobpdc) and mmen-Mg2(dobpdc) were optimized to reduce parasitic energy and increase productivity. The adsorbents, mmen-Mn2(dobpdc), mmen-Mg2(dobpdc) and Zeolite 13X showed minimum parasitic energies of 142, 152 and 167 kWhe/tonneCO2cap, respectively and maximum productivities of 0.4, 0.45 and 0.65 molCO2m-3adss-1, respectively while achieving CO2 purity ⩾95% and recovery ⩾90%. The possible low N2 affinity and the unique shape of the CO2 isotherm were found to be key reasons for a lower energy consumption.