微量Ca对准东煤基多孔碳孔隙结构调控

Adjusting Porosity of Zhundong Coal-based Activated Carbons Based on Catalytically Physical Activation Process With Trace Calcium Source

目前,原料成本高、制备工艺复杂仍是限制高性能多孔碳大规模应用的主要原因。以煤及其衍生物或生物质为原料,采用物理活化法能大大降低制备成本。为提高煤基多孔碳的孔隙结构,本文选用储量大、灰分含量较少的准东煤为原料,利用煤自身及外加矿物质的催化气化作用,研究多孔碳孔隙结构变化规律。研究表明:去灰煤经活化得到典型微孔碳;当煤中含有自身或外加的含Ca组分,经CO_2活化形成分级孔碳,且煤焦结构有序性降低。通过对煤活化前后物相分析及活化反应过程分析,煤自身或外加Ca源的催化气化作用有利于中大孔的形成。同时,球磨辅助处理对孔隙发展有协同促进作用。对制备的多孔碳进行液相污染物脱除实验,发现具有分级孔结构、孔隙发达的多孔碳脱除效率高,球磨后的准东原煤制备的多孔碳在1 min内就达到了400 mg·g^(-1)的吸附量。本研究表明在物理活化制焦过程,通过去除或添加微量的Ca源,就能对孔隙结构起到显著的调节作用。该方法操作简单、无污染,成本低,具有实际工程应用意义。

At present, high raw material cost and complex preparation process are the main keys to limit the large-scale application of high performance porous carbon. Physical activation method has been well commercialized due to low production cost, which is regarded as the simplest and most economical craft. In this work, we select the recently discovered Zhundong coal, a typical low-rank coal as feedstocks and use the catalytic gasification of intrinsic or adding minerals, to study the changing regularity of pore structure for coal-based activated carbons. As a result, the typical microporous carbon was obtained by mineral-free coal sample, while hierarchically porous carbon could be obtained by raw coal samples or Ca-loaded coal samples. The catalytic gasification of the intrinsic or external Ca source was beneficial to the formation of the mesoporons pore through the analysis of the phase before and after the coal activation and the TGA of activation reaction process. At the same time, ball mill assisted processing has synergistic effect on pore development. To verify the application potentials of resulting activated carbons with various pore structure, Rhodamine B （RhB） removal tests were conducted. As-obtained hierarchically porous carbons are applicative for RhB removal. Hierarchically porous ZD（B）-AC has the best performance for RhB adsorption with capacity up to 400 mg·g-1 after I min. This work not only offers a new route for adjusting the porosity of activated carbons during physical activation process, but also provides a simple and scalable method for preparing coal-based activated carbons for rapidly liquid adsorption application.