Copper-Based Sorbents for Coal Gas Desulfurization at Moderate Temperatures

Abstract

In a previous paper, we reported on the development of a regenerable copper chromite sorbent, designated as CuCr-29, that is capable of achieving less than 5 ppmv H2S concentration in the cleaned fuel gas at about 600 °C. This paper reports on recent research carried out to develop a new class of copper-based sorbents for hot fuel gas desulfurization applications in the moderate temperature range of 350−550 °C that is currently of industrial interest. A reproducible sorbent preparation technique has been extended to the formulation of highly reactive and attrition-resistant sulfur sorbents based on reagent-grade oxides of copper, manganese, and alumina. The results of packed-bed experiments carried out for the evaluation of the performance of several copper-based sorbents at 350 and 450 °C as well as the assessment of the long-term durability and regenerability of one selected formulation are presented and discussed. Three copper-based sorbents were shown to exhibit excellent sulfur removal efficiency and effective capacity, with one formulation (IGTSS-145) being particularly effective in the range of 450−600 °C and two formulations (IGTSS-179 and IGTSS-326A) for the range of 350−450 °C. The IGTSS-326A formulation maintained excellent sulfur removal efficiency (<1 ppmv H2S in the cleaned fuel gas) as well as excellent effective sulfur capacity throughout extended durability testing. This sorbent was also shown to have significantly high attrition resistance, as determined in accordance with the ASTM D5757-95 procedure. These results strongly suggest the suitability of this formulation as a candidate sorbent for demonstration in the Sierra Pacific (Piñon Pine) Clean Coal Technology IGCC Demonstration Program.