生物质催化活化褐煤制备活性炭

Biomass catalytic activation of lignite to produce activated carbon

以典型生物质中的K、Na碱金属为催化剂,贵州褐煤为原料,水蒸气为活化剂,利用物理活化法制备活性炭。采用盐酸和氟硅酸混合液联合除灰,当浓盐酸和氟硅酸的体积比为1∶1,脱灰温度为70℃时,脱灰率达85.7%。最佳活化温度及时间均为玉米秸秆<核桃壳<稻壳,与生物质中K、Na碱金属含量的高低顺序相反。生物质添加量过低,催化效果不明显;生物质添加量过高,碱金属密度过高,活化向气化转变。KOH晶体中离子键未断裂,制备的活性炭产生局部大孔,吸附性能降低。当含质量分数8%玉米秸秆的褐煤在725℃下活化1.0 h,所制备的活性炭的亚甲蓝吸附值达164.39 mg/g。利用SEM及BET分析活性炭表面形状和内部孔隙特征,所制备的活性炭疏松多孔,其Langmuir比表面积达1411.2139 m^(2)/g,收率达62.9%。贵州典型生物质催化活化褐煤制活性炭具有可行性,为贵州褐煤制备活性炭及生物质清洁高效利用提供了可行方案。

Using K and Na alkali metal in the typical biomass as the catalyst,Guizhou lignite as the raw material and steam as the activator,the activated carbon was prepared by the physical activation method.The mixed solution of hydrochloric acid and fluorosilicic acid was used to remove ash.When the volume ratio of hydrochloric acid and fluorosilicic acid is 1∶1,and the deashing temperature is 70℃,the deashing rate can reach 85.7%.The optimal activation temperature and time sequence are corn stalk<walnut shell<rice husk,which is opposite to the order of K and Na alkali metal content in the biomass.If the amount of the biomass added is too low,the catalytic effect is not obvious.If the amount of the biomass added is too high,the alkali metal density is too high,and the activation will change to gasification.The ionic bond in the KOH crystal was not broken,and the prepared activated carbon had local macropores,so the adsorption performance was reduced.When the lignite containing 8%corn stalk is activated at 725℃for 1.0 h,the methylene blue adsorption value of the activated carbon can reach 164.39 mg/g.The surface shape and internal pore characteristics of the activated carbon were analyzed by SEM and BET.The activated carbon is loose and porous with Langmuir specific surface area 1411.2139 m^(2)/g,and the yield reaches 62.9%.It is feasible to make activated carbon from lignite by catalytic activation of typical biomass in Guizhou,which provides a set of schemes for making activated carbon from lignite in Guizhou and the clean and efficient utilization of biomass.