The surface chemistry of low-rank coals

✍ Scribed by Keith B. Quast; David J. Readett

• Publisher: Elsevier Science
• Year: 1987
• Tongue: English
• Weight: 715 KB
• Volume: 27
• Category: Article
• ISSN: 0001-8686
• DOI: 10.1016/0001-8686(87)85002-9

✦ Synopsis

The characterization of the surface properties of coals is becoming increasingly important in the understanding of many utilization processes.

While there are numerous publications on the surface characteristics of high rank coals, the lignites have received scant attention. It is the purpose of this paper to show how it is not possible to use the available high rank coal data to predict surface characteristics of the low rank coals; rather, the influence of the high oxygen contents of low rank coals must be considered.

For this reason, the paper traces the changes in the surface chemistry as the rank of the coal decreases from unoxidized high rank coals to oxidized high rank coals to lignites and supports this with data for two South Australian low rank coals.

It is shown that the dissociation of the weakly acidic functional groups (predominantly carboxylates) accounts for the observed surface chemistry; however, the influences of surface heterogeneity, ash forming constituents and high porosity must be taken into account.