H/sub 2/S removal from coal gas at mid-temperature (150 to 200/sup 0/C)

The objective of the program reported here was to develop and evaluate mid-temperature H/sub 2/S removal processes. The program was carried out in two phases divided into four tasks: Phase I Absorbent Evaluation (chemistry, mass transfer); Phase II Process Development and Evaluation (process evaluation, slip stream verification). The absorption reactions proposed for mid-temperature H/sub 2/S removal processes are the precipitation of metal sulfate or metal hydroxide to metal sulfides, and the oxidation of H/sub 2/S for production of elemental sulfur and sulfates. Zinc, nickel, and iron were evaluated as metal sulfate or hydroxide absorbents. Organometallic redox reagents and compounds of nickel or iron were employed as absorbents for processes involving oxidation of H/sub 2/S. These processes were evaluated in Tasks I, II, and III; in Task IV the most promising processes were demonstrated on a slip stream from the gasifier. The direct oxidation process with either NiSO/sub 4/ or Fe(OH)/sub 3/ absorbent was selected for further devaluation in Task III. The operating conditions for each process were determined using simulated coal gas. Regeneration of absorbents was studied. In Task IV, the direct oxidation process was operated with a slip stream of coal gas produced by the GE fixed-bed gasifier. Themore » H/sub 2/S and COS absorption efficiency and optimum operating conditions for operation with coal gas were determined. The overall applicability of the direct oxidation process was evaluated. 21 figures, 24 tables.« less