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The overall objective of this study is to determine the effectiveness of the copper-chromite sorbent (developed in previous ICCI-funded projects) for longer duration application under optimum conditions in the temperature range of 550{degrees}-650{degrees}C to minimize sorbent reduction and degradation during the cyclic process. To achieve this objective, several formulations of copper chromite sorbents are prepared. These sorbent formulations are screened for their desulfurization and regeneration capability at predetermined temperatures and gas residence times. The durability of the best sorbent formulation identified in the screening tests is evaluated in ``long-term`` durability tests conducted at the optimum operating conditions. This includes testing the sorbent in pellet and granular forms in packed- and fluidized-bed reactors. During this quarter, twenty one copper chromite-based sorbent formulations were prepared. Two sorbent formulations that have acceptable crush strength, designated as CuCr-10 and CuCr-21, were tested over 5 and 6 cycles respectively. The results indicate that both sorbents are reactive toward H{sub 2}S at 650{degrees}C and that the reactivity of the sorbents are relatively constant over the first 5 to 6 cycles. The H{sub 2}S prebreakthrough concentrations were generally about 20 to 30 ppm, making them suitable for IGCC application.

The objective of this investigation is to evaluate two novel copper-based sorbents, namely copper-chromium and copper-cerium, for their effectiveness in removing hydrogen sulfide from fuel gas in the temperature range of 650 to 850 C. Such high temperatures will be required for the new generation of gas turbines (inlet > 750 C) in Integrated Gasification Combined Cycle (IGCC) systems. Results of fixed-bed reactor tests conducted in this quarter, indicate that, at 750 C, pre-reduction with H{sub 2} in the presence of H{sub 2}O does not effect the performance of either sorbent for H{sub 2}S removal. For the pre-reduced CuCr{sub 2}O{sub 4} sorbent, copper utilization before the first H{sub 2}S breakthrough is substantially higher in synthesis feed gas mixture than in feed gas containing 30 Vol% H{sub 2}, and slightly lower than in 10 vol% H{sub 2}. In sulfidation-regeneration testing of copper- and additive-rich sorbents, chromium-rich CuO-3Cr{sub 2}O{sub 4} sorbent demonstrated very high H{sub 2}S removal efficiency and high copper conversion levels (comparable to that of the 1:1 molar composition sorbent). Similar results were obtained with the cerium-rich CuO-3CeO{sub 2} sorbent, but only for the first cycle. The H{sub 2}S removal performance of both copper-rich sorbents was inferior to that ofmore » the respective 1:1 molar compositions. CuO-CeO{sub 2} sorbent testing in a TGA indicates no appreciable decrease in the sulfidation rate over 5 1/2 cycles. However, weight changes during regeneration of the CuO-CeO{sub 2} suggest that some copper or cerium sulfates formed.« less

The objective of this investigation is to evaluate two novel copper-based sorbents, namely copper-chromium and copper-cerium, for their effectiveness in removing hydrogen sulfide from fuel gas in the temperature range of 650{degree} to 850{degree}. Such high temperatures will be required for the new generation of gas turbines (inlet >750{degree}C) in Integrated Gasification Combined Cycle (IGCC) systems. The effect of pre-reduction with H{sub 2}, in the presence of H{sub 2}O on the performance of the sorbents in cyclic sulfidation/regeneration, was studied in a thermogravimetric analyzer (TGA) and in a fixed-bed reactor at 750{degree}C. The results of the TGA tests indicate that pre-reduction of the sorbents is very fast in either 10% or 30% H{sub 2}. Without sorbent pre-reduction, sulfidation consists of two-stages, a reduction-dominating and a sulfidation-dominating stage. Sulfidation apparently takes place before reduction is complete. During regeneration some copper/cerium sulfates may have formed and Cu{sub 2}O may have formed in addition to CuO. The fixed-bed reactor tests show that at 750{degree}C: (1) prereducing the CuO-Cr{sub 2}O{sub 3} with H{sub 2} does not effect the reactivity of the sorbent towards H{sub 2}S at either the high or low H{sub 2} feed gas concentrations and (2) when 30% H{sub 2} was usedmore » during sulfidation of either sorbent, the first H{sub 2}S breakthrough occurs earlier than when 10% H{sub 2} was used.« less

The objective of this investigation is to evaluate two novel copper-based sorbents, namely copper-chromium and copper-cerium, for their effectiveness in removing hydrogen sulfide from fuel gas in the temperature range of 650{degree} to 850{degree}C. Such high temperatures will be required for the new generation of gas turbines (inlet >750{degree}C) in Integrated Gasification Combined Cycle (IGCC) systems. The effect of pre-reduction on the performance of the sorbents as well as the rate of different reactions occurring in cyclic sulfidation/regeneration, were studied in a thermogravimetric analyzer (TGA). Sulfidation was conducted with and without H{sub 2} and H{sub 2}O, and with and without pre-reduction in H{sub 2} or H{sub 2}/H{sub 2}O. The results of these tests indicate that reduction and regeneration of both sorbents occurs rapidly. Sulfidation of CuCr{sub 2}O{sub 4}, in H{sub 2}O-free and H{sub 2}-/H{sub 2}O-free gas indicates the possible sulfidation of both copper and chromium. Small quantities of SO{sub 2}, were released during sulfidation suggesting the possible oxidation of H{sub 2}S by the sorbent. Regeneration of the CuCr{sub 2}O{sub 4} was complete while regeneration of the CuO-CeO{sub 2} indicated possible limited sulfate formation.

The objective of this investigation is to evaluate two novel copper-based sorbents (i.e. copper-chromium and copper-cerium) for their effectiveness in removing hydrogen sulfide from fuel gas in the temperature range of 650{degrees} to 850{degrees}C. In this program, structural and kinetic studies are conducted on various compositions of the two selected copper-based sorbents to determine the optimum sorbent composition. The effect of operating conditions on the performance of the sorbents alone with the stability and regenerability of the selected sorbents in successive sulfidation/regeneration operation are determined. Parametric multicycle desulfurization tests were conducted this quarter in a bench-scale (5-cm-diameter) quartz reactor at one atmosphere using the CuCr{sub 2}O{sub 4} and CuO/CeO{sub 2} sorbents. The parameters studied included temperature, space velocity, and feed gas composition. Both sorbents were able to reduce the H{sub 2}S concentration of the reactor feed gas to

The objective of this investigation is to evaluate two novel copper-based sorbents (i.e. copper-chromium and copper-cerium) for their effectiveness in removing hydrogen sulfide from fuel gas in the temperature range of 650[degree] to 850[degree]C. New sorbent compositions from the selected Cu-Cr-O and Cu-Ce-O binary oxides were prepared and characterized by BET N[sub 2]-desorption surface area measurement following various calcination/time-temperature exposures. The general trends reported last quarter (on 11 different compositions) were validated this quarter in that both binary oxides lose surface area as the amount of CuO is increased. Time-resolved sulfidation tests were conducted at 850[degree]C using the equimolar CuO.Cr[sub 2]O[sub 3] composition. The two selected binary oxides prepared in larger qauntities (for testing in a two-inch reactor) have physical properties typical of the sorbents prepared in past programs. Two multicycle desulfurization tests, conducted this quarter on the Cu-Ce-O sorbent at 850[degree]C, using a feed gas containing 5000 ppm H[sub 2]S, 10 vol % H[sub 2] and 10 vol % H[sub 2]O at a space velocity (STP) of 2000 h[sup [minus]1], demonstrated high sulfur removal efficiency for the first one or two cycles, and a significant reduction in efficiency in the following cycles.

The objective of this investigation is to evaluate two novel copper-based sorbents, namely Cu-Cr and Cu-Ce, for their effectiveness in removing hydrogen sulfide from fuel gas in the temperature range of 650 to 850 C. Such high temperatures will be required for the new generation of gas turbines in Integrated Gasification Combined Cycle systems. Structural and kinetic studies were conducted on various compositions of the two Cu-based sorbents to determine the optimum sorbent composition. The effect to operating conditions on the performance of the sorbents along with the stability and regenerability of the selected sorbents in successive sulfidation/regeneration operation were determined. Overall, the CuO-lean binaries (with Cr{sub 2}O{sub 3} or CeO{sub 2}) may benefit the H{sub 2}S breakthrough levels. While this is at the expense of sulfur capacity for the Cu-Cr-O sorbents, it may not affect the capacity of the Cu-Ce-O sorbents. Parametric multicycle desulfurization tests were conducted in a bench-scale quartz reactor at one atmosphere using the CuCr{sub 2}O{sub 4} and CuO-CeO{sub 2} sorbents. The parameters studied included temperature, space velocity, and feed gas composition. Both sorbents were able to reduce the H{sub 2}S concentration of the reactor feed gas from 5,000 ppmv to less than 1 ppmv tomore » 10 ppmv at 750 to 850 C. Both sorbents were found to consume H{sub 2} and produce SO{sub 2} during the initial stages of sulfidation. Analysis of partially sulfided samples identified predominantly Cu metal, the additive oxide and small amounts of oxidic copper. For the Cu-Cr-O sorbents, the latter is apparently sufficient to keep the H{sub 2}S pre-breakthrough levels as low as has been reported in this work. For the Cu-Ce-O sorbents, in which very little or no oxidic copper remained, the low H{sub 2}S levels may be due to the participation of CeO{sub 2}, whose sulfidation is promoted by Cu.« less

The objective of this investigation is to evaluate several novel copper-based binary oxides for their suitability as regenerable sorbents for hot gas cleanup application in the temperature range of 650{degrees} to 850{degrees}C. During this quarter cyclic sulfidation/regeneration tests of the sorbents Cu{sub 2}Cr-O and Cu-Ce-0 were conducted using different compositions of the feed gases to investigate the effects of H{sub 2}0, H{sub 2} and CO. These tests were conducted in a packed-bed microreactor at 850{degrees}C. The results of these tests showed that H{sub 2} and CO (along with C02) had a significant effect on the H{sub 2}S pre-breakthrough levels, whereas H{sub 2}0 did not have an effect. The physical properties of the fresh and reacted samples of the Cu-2Cr-O and Cu-Ce-0 sorbents prepared in this program and used in the cyclic sulfidation/regeneration tests were also measured. In addition, sulfidation/regeneration tests were conducted using two commercial copper chromite sorbents (G-13 and G-89, United Catalyst, Inc.) and a zinc titanate sorbent (L-3014) in a one-inch fluidized-bed reactor at 650{degrees}C. The G-13 sorbent appears to have a much higher sulfur capacity than the G-89 sorbent.

The objective of this investigation is to evaluate several novel copper-based binary oxides for their suitability as regenerable sorbents for hot gas cleanup application in the temperature range of 650{degrees} to 850{degrees}C. To achieve this objective, several novel copper-based binary oxide sorbents will be prepared. Experimental tests will be conducted at ambient pressure to determine the stability, sulfidation capacity, regenerability, and sulfidation kinetics of the novel sorbents. Tests will also be conducted at high pressure for the determination of the sulfidation reactivity, regenerability, and durability of the sorbents. The attrition characteristics of the sorbents will also be determined.