基于活化过程碳烧失特性的孔结构发展机制

以太西无烟煤和大同烟煤为原料，在不同活化温度下制备了烧失率10%~75%的活性炭。研究了活化过程中无规则碳和微晶单元结构的烧失特性，并分析了表面碳烧失特征；结合不同活化阶段的孔结构特性，分析了微孔、中孔形成及发展机制。结果表明，当烧失率低于30%时，以无规则碳烧失为主，无烟煤活性炭主要形成1.35 nm以下的微孔，而烟煤活性炭同时形成微孔和中孔结构，且中孔孔径可达到50 nm。随烧失率的增加，微晶结构参与反应，当烧失率超过50%时，层片尺寸和堆积厚度均明显减小。此时无烟煤活性炭在微晶结构间发生扩孔作用，持续发展2~4 nm的中孔，同时微晶层间距增加也可发展极微孔。烟煤活性炭微晶单元尺寸显著减小，会造成孔结构坍塌或萎缩，导致原有孔容积降低。

Development mechanism of pore structures based on burn-off properties of carbon structures during activation process

By picking Taixi anthracite and Datong bituminous coal as the feedstocks,the activated carbons with 10%-75% burn-offs were prepared at different activation temperatures.The burn-off properties of amorphous carbon and crystalline structure were investigated,and the external carbon loss of the particle was also considered.Combined with the textural characteristics of activated carbons in different activation stages,the formation and development mechanism of micropore and mesopore were explained.The results indicated the amorphous carbon got burnt when the burn-off was lower than 30%.The micropores which pore size was smaller than 1.35 nm were formed in TX-activated carbons.By comparison,the micropore and mesopore could be formed simultaneously in DT-activated carbons,and the mesopore size could reach to 50 nm.As the burn-off increasing,the crystallite reaction began to take place.When the burn-off was higher than 50%,the crystallites reduced not only in thickness,but also in layer sizes.In this stage,the mesopore of 2-4 nm could be developed continuously between the crystalline structures by etching action,and the ultramicropores could be formed in the inner part of the crystallites as the increase of lamellar spacing.As a rapid shrinking of crystallites in DT-activated carbons,the pore structure could collapse and shrink leading to the reduction of original pore volume.