Preparation of zinc ferrite in the presence of carbon material and its application to hot-gas cleaning

In order to develop an efficient absorbent of H,S in coal gasification, zinc ferrite (ZnFe2O4) was prepared in the presence of carbon materials such as activated carbon (AC), activated carbon fiber (ACF), and Yallourn coal (YL). The absorption behavior of absorbents for H2S was examined using a fixed-bed flow type reactor equipped with a quadrupole mass spectrometer. Carbon material-supported ZnFe2O4 exhibited larger desulfurization capacity for H2S than unsupported ferrites. They could efficiently remove H2S from 4000 ppm levels in a simulated coal gasification gas to less than I ppm at 500 degreesC. The absorption capacity of H2S with ZnFe2O4/AC, ZnFe2O4/ACF, and ZnFe2O4/YL exhibited nearly 100% of stoichiometric amount of loaded metal species. They could be regenerated by an air oxidation in O-2-Ar (50 vol%) at 450 degreesC for 30 min. The regenerated ferrite can be used for repeated absorption of H2S with a very slight decrease in the absorption capacity. (C) 2003 Elsevier Ltd. All rights reserved.