Zeolite versus carbon adsorbents in carbon capture: A comparison from an operational and life cycle perspective

Abstract

New materials are continuously developed for carbon capture from flue gases being zeolites and carbon-based adsorbents the most used. The determination of the environmental impacts of using each different adsorbent is critical for the sustainability of the carbon capture process. To attain this purpose, a life cycle assessment (LCA), using carbon capture data based on experimental vacuum pressure swing adsorption (VPSA), was conducted concerning two highly efficient adsorbents, a zeolite (13X-APG) and a carbon molecular sieve (CMS-330). All the key performance indicators studied had better values with 13X-APG than CMS-330. The LCA results indicate that the zeolite scenario shows around 13 % lower environmental loads in all categories than the CMS-330 scenario. Moreover, the use stage is the main hotspot dominating the life cycle contributing more than 96 % in the life cycle impacts. Sensitivity analysis results show that the replacement of the adsorbent and its treatment as waste is not so critical as the amount and type of energy consumed during the VPSA. The results point out that if renewable energy was used, the carbon capture efficiency of the VPSA would increase up to 96 % and 84 % for the 13X-APG and CMS-330 respectively. Accordingly, the LCA results elucidated that the use of the zeolite for carbon capture has less environmental impacts than the CMS-330. As a perspective, further investigations are strongly recommended for alternatives carbon capture adsorbents and the present study sounds to provide a guideline towards this purpose.