Catalytic Activity of Coal Char on Water-Gas Shift Reaction

Abstract

Catalytic activity of coal chars on the water–gas shift (WGS) reaction has been investigated in a fixed bed reactor at various temperatures in the range of 700–900°C. Two coal chars employed in this study (char A and char B) are signed with relatively high ash contents. The results show that WGS reaction occurred over both chars. Under the experimental conditions studied, the reaction rate towards hydrogen formation may be described as: rH2 = 2.17 × 109 exp(124,800/RT)(pCOpH2O – pCO2pH2/K) for char A and rH2 = 8.0 × 108 exp(127,900/RT)(pCOpH2O – pCO2pH2/K) for char B. The two chars showed different catalytic behaviors. Gas yield obtained from WGS reaction over char A was higher than that from char B. The higher catalytic activity of char A in WGS reaction was due to the combination of higher specific surface area, the presence of very fine and well-dispersed particles of mineral matters on the char surface, and also the high content of iron oxide fixed for each experiment. Demineralized char A still showed a catalytic activity due to the abundant amount of mesopores, whereas it was lower than char A, which indicates the importance of the mineral matters on the progress of WGS reaction.