Changes in active sites and reactivity induced by interactions among Ca, Si and Al during coal char gasification

Chemical structure of char plays an essential role in coal gasification reactivity, especially functional groups and active site. In this study, reactivity difference was discussed by integrating functional groups, mineral interactions with active site. A thermogravimetric analyzer was applied to determine the active site by adsorption and desorption process. X-ray photoelectron spectroscopy (XPS) results prove that coal char loaded Ca (Ca + Dem-char) and the char containing Ca, Si and Al (Ca+(Si, Al)-char) have fewer ratio of ether (-C-O-C-)and carbonyl (-C=O) groups because Ca species facilitate the decomposition of these groups in pyrolysis. Active site analysis illustrates that compared with demineralized char (Dem-char), char with Si and Al ((Si, Al)-char) has the smallest amount of active site, which is the direct factor for an inferior gasification reactivity, because Si and Al not only have no function to adsorb gasifying agent but also block some active site and even make some carbon become inert.

Automated summary

The chemical structure of char is crucial for coal gasification reactivity, with functional groups and active sites playing key roles. The study found that char containing Si and Al has the least amount of active sites, leading to inferior gasification reactivity. Furthermore, it was discovered that Ca species facilitate the decomposition of ether and carbonyl groups in pyrolysis.