Highly active iron catalysts from ferric chloride for the steam gasification of brown coal

Abstract

A new method for preparing active iron catalysts for coal gasification at low temperatures has been studied by using FeCl[sub 3] as a raw material. Iron catalysts are precipitated onto brown coal probably in the form of FeOOH from an aqueous solution of FeCl[sub 3] by using three additives (urea, Ca(OH)[sub 2], and ammonia) and by hydrolysis. The use of Ca(OH)[sub 2] gives the highly dispersed, most active iron catalyst, which achieves complete gasification in steam within 60 min at 973 K and at 5 wt % Fe. The specific gasification rate with the most active catalyst is about 20 times that without catalyst, and it increases as the reaction proceeds. The X-ray diffraction measurements show that Fe[sub 3]O[sub 4] is the stable species throughout the gasification regardless of the catalyst preparation method. The sequence of catalyst effectiveness and the difference in the rate profiles among these catalysts can be elucidated on the basis of the degree of Fe[sub 3]O[sub 4] dispersion.