Preparation Of Activated Carbon From Petroleum Coke By Microwave And Characterization Of CO₂ Adsorption

As Greenhouse effect has become a global environmental problem. Recycling of CO₂, one significant greenhouse gas has drawn much attention. Activated carbon as a porous carbon material, which has good adsorption property, is widely used as adsorbent in gas separation process.In this paper, petroleum coke was used as raw material, furfural residue as pore-forming agent and KOH as active agent to prepare activated carbon. Two heating methods including electricity and microwave were employed. The adsorption ability of prepared activated carbon was characterized by the adsorption of nitrogen, iodine and benzene. The effects of the content of furfural residue, the weight ratio of KOH to petroleum coke, microwave power and the effect of the irradiation time on pore structure were studied by orthogonal design. The prepared activated carbon was used in CO₂ separation process.For the preparation of activated carbon by microwave, the sequence in terms of influence degree was as follows: the content of furfural residue, the ratio of KOH to petroleum coke, microwave power, irradiation time. The optimum conditions were as follows: Weight ratios of KOH, petroleum coke and furfural residue are 5:1:0.67, the power of microwave was 1200W and the irradiation time was 10 minutes.The specific surface area of prepared activated carbon was 1391.0m2·g^-1, the iodine capacity was 1591.6mg·g^-1, and the benzene capacity was 550.8mg·g^-1 respectively. The CO₂ adsorption capacity of the activated carbon was 236.2 mg·g^-1.The results show that the micropore volume, the BET surface area and CO₂ adsorption of activated carbon increased with appropriate amount of furfural residue to the system. The micropore volume and pore size were closely related to the CO₂ adsorption capacity, but other parameters such as surface functional groups were not so closely related. The pore volume of activated carbon made by microwave was two times higher than that of activated carbon made by electricity in 0.5-1.0nm. The pore size in 0.5-1.0nm was beneficial to CO₂ adsorption. It was also found that surface polarity of activated carbon affects the CO₂ adsorption capacity. Within the scope of the study, the activated carbon oxidized by nitrate acid with the concentration of 4mol·L^-1 had a better CO₂ adsorption capacity. And the CO₂ adsorption capacity of the activated carbon made by microwave was better than that of electricity.