超级活性炭的合成及活化反应机理

Synthesis and Activation Mechanism of Coke Based Super Activated Carbons

以石油焦为原料,采用碱熔活化法合成出具有超高比表面的超级活性炭.借助XRD、TG-DTA、N2吸附实验等手段,对其结构与性能进行了表征.同时,设计原位TG-DTA测试技术、反应快速终止技术,对超级活性炭合成机理进行了考察,提出了两段活化反应机理,即中温径向活化机理和高温横向活化机理.发现K2O、-O-K+以及-CO-2K+是径向活化为主的中温活化段的活化剂活性组分,而处于熔融状态的K+O-、K+则是横向活化为主的高温活化段的催化活性组分.并发现径向活化是超级活性炭形成发达微孔分布的主要途径,也是控制超级活性炭微孔分布的主要手段.而高温横向活化机理则是导致超级活性炭形成大孔的主要途径.高温横向活化与中温径向活化一起构成石油焦基超级活性炭形成的主要机理.

Coke based super activated carbons(SAC)with higher surface area were synthesized by means of KOH thermo-activation.The structu re and properties of SAC samples were extensively investigated by TG-DTA and N2 adsorption techniques.Simultaneo usly,in-situ TD-DTA and quick activation quenchi ng techniques were designed to investigate the activation mechanism of SAC samples.A two-s tep activation mechanism,which in-cludes radial activation at moderate temperature and transverse activation at higher temperature,respectively,was tentatively postulated.It indicated that K2O,-O-K+and -CO-2K+might be the active sites of radial ac tivation at moderate temperature and fused K+ O- and K+might be the active centers of transv erse activation at higher tem-perature.Of special is that radial activation at moderate temperature m ay result in the formation of micropo res and that this might be the effective way t o improve the micropore distributio n of SAC samples.In contrary,the tra ns-verse activation at higher temperature would lead to the formation of macropore.The formation of super activ ated carbons was resulted from the radial activation at moderate temperature and subsequent transverse activati on at higher temperature.