Fixed bed testing of a molybdenum-promoted zinc titanate sorbent for hot gas desulfurization

Abstract

The experimental test program for the molybdenum-promoted zinc titanate with Zn/Ti ratio of 1.91, consists of two series of test: six half-cycle (sulfidation phase) parametric tests and four multi-cycle (sulfidation and regeneration phase) tests. Results of the parametric tests were utilized to select the optimum conditions for multi-cycle tests. The intent of the multi-cycle test series was to demonstrate durability and regenerability of the molybdenum-promoted zinc titanate sorbent. During the parametric tests, sorbent bed temperature and linear velocity were varied. However, system pressure was fixed at 150 psia (1.03 MPa) for sulfidation test phases and 50 psia (0.34 MPa) for regeneration test phases for both single and multi-cycle tests. Figure 2 shows the effect of gas flow rate and temperature on hydrogen sulfide removal during the half-cycle (sulfidation) parametric tests. Simulated KRW coal gas which contained 15 vol% H{sub 2}, 21 vol% CO, 9.0 vol% H{sub 2}O and 800 ppmv H{sub 2}S was used during the parametric tests. As can be seen from the data, sorbent efficiency and capacity were only weak functions of bed temperature. However, increasing the space velocity substantially reduced sorbent efficiency and capacity as indicated on the rapid breakthrough of H{sub 2}S for the high space velocity. Breakthrough period is defined here as corresponding to H{sub 2}S concentration of 200 ppmv in exit gas.