Investigation of alkali and alkaline earth coal gasification catalysts by EXAFS spectroscopy

✍ Scribed by G.P. Huffman; F.E. Huggins; R.G. Jenkins; A. Piotroswski; F.W. Lytle; R.B. Greegor

• Publisher: Elsevier Science
• Year: 1986
• Tongue: English
• Weight: 718 KB
• Volume: 65
• Category: Article
• ISSN: 0016-2361
• DOI: 10.1016/0016-2361(86)90100-6

✦ Synopsis

EXAFS spectroscopy

and several supplementary techniques have been used to investigate a variety of coal and polymer chars containing alkali and alkaline earth catalysts, including Ca, K and Rb. In-situ EXAFS measurements were performed on Rb-loaded chars during gasification. At 450°C in 90% N,-10% O,, the Rb XANES exhibited a doublet structure similar to that of Rb,O and Rb,CO,. EXAFS and other techniques show that the Ca in lignites, both naturally occurring and ion-exchanged, is essentially molecularly dispersed and bonded to carboxyl groups. Calcite-like features are induced in both the near-edge structure and radial structure functions of chars with increasing pyrolysis time and temperature.

The structure of K is found to differ significantly in polymer, lignite and bituminous coal chars.