葡萄树基活性炭的制备及其CO_(2)吸附特性

Preparation of Grape Tree Based Activated Carbon and Its CO_(2) Adsorption Capacity

为探讨葡萄树基活性炭在碳捕集与封存领域中的潜力,分别以葡萄树枝和树皮为原料采用CO_(2)活化法在800℃下制备了葡萄树枝基活性炭和葡萄树皮基活性炭,根据N 2物理吸附法计算了比表面积,用二维非定域密度函数理论(2D-NLDFT)分析了孔径分布特性,并使用热重分析法表征了两种活性炭的热解特性以及30℃的CO_(2)吸附特性.结果表明:①葡萄树枝基活性炭具有微孔结构,微孔孔径在0.36~1.6 nm之间,孔径为0.66 nm的微孔最多;葡萄树皮基活性炭具有大量微孔和少量中孔,孔径主要集中在0.36~1.9 nm之间.②葡萄树枝基和葡萄树皮基活性炭的CO_(2)吸附容量分别为1.096和0.247 mmol/g.③两种活性炭的CO_(2)吸附以物理吸附为主,其CO_(2)饱和产物在45℃前释放全部CO_(2),葡萄树枝基活性炭的CO_(2)饱和产物较葡萄树皮基活性炭的CO_(2)饱和产物难于释放CO_(2).④两种活性炭吸附CO_(2)后,在热重特性上出现的微量变化表明活性炭物质结构上的变化.研究显示,葡萄树枝基活性炭是一种良好的CO_(2)捕集材料,但其CO_(2)吸附容量比其他同类活性炭低,CO_(2)吸附量较高的葡萄树基活性炭的制备条件和改性方法需要进一步研究.

In order to analyze the potential of grape tree-based activated carbon in the carbon capture and storage,the grape tree branch and bark-based activated carbons were prepared by CO_(2) activation method at 800℃.The surface area of activated carbons was characterized by N 2 adsorption,PSD was analyzed by 2D-NLDFT method,and thermal decomposition and CO_(2) adsorption capacities were tested by thermo-gravimetric method.The results showed that:(1)The grape branch-based activated carbon was microporous,with a micropore size of 0.36-1.6 nm and an average size of 0.66 nm.The grape bark-based activated carbon had a micro-mesoporous texture,with a micropore range of 0.36-1.9 nm.(2)The CO_(2) capacities of grape branch and bark-based activated carbon were 1.096 and 0.247 mmol/g,respectively.(3)The activated carbons mainly adsorbed CO_(2) by physical force,and released all the adsorbed CO_(2) at a temperature below 45℃.The CO_(2) adsorbed by grape branch-based activated carbon was more difficult to be released than that adsorbed by the grape bark-based activated carbon.(4)There was little difference in thermo-gravimetric properties of the two carbons,and their CO_(2)-saturated products indicated little change in surface structure.The study showed that grape branches are preferred precursors for CO_(2) capture by adsorption.However,new methods for preparing and modifying the grape-tree based activated carbons with higher CO_(2) adsorption capacity need to be developed due to its relatively lower adsorption capacity than similar products.