Raman Spectroscopic Investigations into Links between Intrinsic Reactivity and Char Chemical Structure

摘要

There are a large number of factors affecting the gasification reactivity of chars, includingphysical structure (e.g. surface area and pore structure), catalytically-active mineral matter,and chemical structure which includes the extent of crystallinity of the carbonaceous matrixand also the nature of the functional groups that comprise the char structure. This workfocuses on the latter, using Raman spectroscopy to investigate the relationships betweenintrinsic reactivity and char chemical structure. An Australian bituminous coal char and aChinese lignite char were characterised in terms of their intrinsic reactivities with CO_2 andH_2O (separately), under conditions where chemical processes control the observed reactionrates (Regime I). Unreacted and partially-reacted chars were characterised using Ramanspectroscopy and gas adsorption for determination of chemical structure indicators andsurface area respectively. Raman spectra suggested that the ratio of small to large aromaticrings decreased with increasing carbon conversion, and for the bituminous coal char, thisseemed to be linked to the reactivity behaviour of chars made from the bituminous coal. Theintrinsic reactivity of chars made from the lignite seemed to have a less significant correlationwith Raman features, possibly due to the relative influence of catalytic activity of inorganicspecies.