Evaluation of novel adsorbents for CO2 mitigation in a diesel engine exhaust-an experimental assessment
摘要
Anthropogenic carbon dioxide (CO2) is the most prominent greenhouse gas (GHG) that creates severe global issues and is facing worldwide. Combustion of fossil fuels liberates more CO2, which builds up in the atmosphere and has a more significant potential to cause global warming potential (GWP) and the anthropogenic climate crisis. In spite of that, research efforts have been made to reduce CO2 emissions from important single-point sources, viz., compression ignition (CI) engines, compact stationary generator units, and dispersed power generation systems. Post-combustion carbon capture has been the subject of some research studies aimed at reducing CO2 emissions from small stationary engines and vehicle exhaust units. Currently, biomass-based carbon capture material is a suitable adsorbent for mitigating CO2 from the tailpipe emissions. Three biomass-based CO2 capture materials, particularly: (i) walnut-shell adsorbent (WSA), (b) rice-straw adsorbent (RSA), and (c) sugarcane-bagasse adsorbent (SBA) are employed in the exhaust treatment chamber to capture CO2 emissions predominantly in the engine’s exhaust. The adsorption efficacy of the adsorbent samples is determined by using an adsorbent-loaded exhaust treatment unit mounted to the exhaust system. The engine operates in 100% diesel mode (D100) at different load conditions. Tests are performed to evaluate adsorbents’ adsorption performance in terms of pollutant reduction. The essential adsorbents’ adsorption parameters are investigated and discussed. Temperature swing adsorption (TSA) is utilized as a desorption method to restore the initial adsorbent material in the exhaust treatment unit. The spent adsorbent materials are utilized for the cyclic operation of adsorption–desorption processes to investigate their adsorption ability on several test cycles. The gas emitted from the exhaust treatment unit during TSA operation is again collected and retained in a container. The collected test specimen is subjected to Gas Chromatography-Mass Spectroscopy (GC–MS) techniques to assess the material’s gas adsorption rates. At 1 bar and 10 °C, the highest uptake capacity of samples is achieved by 5.25 mol kg−1, 4.15 mol kg−1, and 5.75 mol kg−1 for WSA, RSA, and SBA samples, respectively. In the post-combustion carbon unit, CO2 is captured about 24%, 33% and 45%, respectively, for WSA, RSA, and SBA samples, respectively.
Graphical abstract