Effect of iron on Shenfu coal char structure and its influence on gasification reactivity

•Iron atoms inhibit the trend of graphitization of coal char during pyrolysis process.•Iron inhibits the growth of large aromatic ring structure and increases the amount of amorphous carbon structure in char.•The presence of iron promotes the direct interaction between carbon and water.

The influence of iron on Shenfu coal char structure and its gasification reactivity was studied in the present paper. Acid-washing coal samples were loaded with different content of iron catalyst and then pyrolyzed at 1123 K. X-ray diffraction apparatus and Raman spectra apparatus were used to characterize the structure of coal char. The char gasified with CO2 in a thermogravimetric analyzer to study the effect of iron loading on the gasification reactivity. Iron catalyzed steam gasification of char was carried out in a fluidized-bed reactor to investigate the impact of iron loading on the release characteristics of gas products. The results of XRD suggested that iron particle effectively hinders the trend of carbon graphitization in the process of pyrolysis. The intensity of (0 0 2) and (1 0 0) peaks of char decreased with the rise of iron loading. With the increase of iron loading, Lc and La reduced from 12.48 Å and 41.40 Å to 11.50 Å and 35.70 Å, respectively. Raman spectra analysis showed that iron inhibits the growth of large aromatic ring structure and increases the amount of amorphous carbon structure in char. Comparison of the reactivity of char loaded with various concentrations of iron catalyst, the char with 2 wt% iron exhibited highest gasification reactivity. It was found that iron catalytic gasification reaction generates much more product gas than that of un-catalyzed. In particular, the presence of iron promotes the direct interaction between carbon and water.