(648a) A Cost-Effective Nanoporous Carbonaceous CO2 Adsorbent Synthesized from Bitumen Coke

Carbon dioxide is the main greenhouse gas emitted by industrial operations from the combustion of fossil fuels (coal, oil and natural gas). CO₂ capture by adsorption is recognized as an effective technology in mitigating global warming issues. There is a growing interest in synthesizing CO₂ adsorbents from waste materials, considering both cost-effectiveness and environmental concerns. This study investigates the production of high-value porous activated carbon from bitumen coke, specifically designed for CO₂ capture, aiming to broaden the utilization of bitumen coke.

The carbonaceous adsorbent was synthesized using KOH activation through two mixing methods: wet and dry mixing, and different activation routes. The synthesis process employed different weight ratios of KOH/coke and activation temperatures for 1 hour. The specific surface area and total pore volume of the resulting adsorbents increased proportionally with the ratio of KOH/coke, achieving up to 2638 m²/g and 1.39 cm³/g, respectively. Notably, the sample produced under optimal conditions, with a KOH/coke weight ratio of 2:1 and an activation temperature of 800 ^â—¦C via the wet mixing, exhibited the highest CO₂ adsorption uptake of 6.3 mmol/g at 0 ^â—¦C under atmospheric pressure. The repetition test of CO₂ adsorption on the selected sample indicated a great regeneration property of the synthesized adsorbent. The study revealed a linear correlation between CO₂ adsorption uptake and the volume of micropores smaller than 0.8 nm, shown in Fig. 1. This underscores the significance of a narrow micropore volume for effective CO₂ adsorption. To improve the performance of CO₂ adsorption, the selected adsorbent was functionalized with nitric acid. This treatment resulted in a 20% increase in CO₂ adsorption performance.

Overall, the carbonaceous adsorbents showed rapid adsorption, easy regeneration, and stable performance over multiple adsorption-desorption cycles, making them promising for CO₂ capture applications.