Sorbents For Hot Gas Desulfurization Research Articles

The Recovery of Sulfur Resource during Regeneration Process for the Hot Gas Desulfurization Sorbent

Recovery of sulfur source is an important goal of industrialization regeneration for hot coal gas desulfurization sorbent. The different sulfide forms of sulfur produced in regeneration atmosphere and the method for recovering of sulfur source are discussed in this paper. The regeneration exhausted gas of high temperature desulfurization sorbent mainly has several forms of sulfides: sulfur dioxide, hydrosulfide and elemental sulfur, sulfide form and regeneration atmosphere have a direct relationship. Recovering sulfur dioxide utilize the reduction of CO or ammonia, and recovering hydrosulfide use selective catalytic oxidation which is the desulfurization method for achieve prospects of industrialization, but there is catalyst poisoning in these methods. We point out that the direct recovery of elemental sulfur from different forms of sulfide will be the focus of future research.

Study on Deactivation of Zinc-Based Sorbents for Hot Gas Desulfurization

The possible reasons that were associated with the reduction of zinc oxide and the deposition of elemental Zn on the zinc-based sorbent surfaces were proposed in this study and examined by monitoring chemical reactivity and physical/chemical properties of the sorbents during the multicyclic tests with the aid of various diagnostics in order to investigate the deactivation of the sorbents that was observed in previous works. The reactivity of the sorbents was investigated using a temperature programmed technique (TPT) with a thermal gravimetric analyzer (TGA). From our experiments, the undesirable features due to the reduction of ZnO that was caused by the reducing components in the gasified coal gas were observed in the chemical reactivity and sorbent properties. In the investigation of the migration of elemental Zn onto the sorbent surface, elemental Zn accumulated on the surface of the sorbents rather than the zinc vaporization. It might have caused the deactivation of the zinc-based sorbents.

Effect of binder on the properties of iron oxide sorbent for hot gas desulfurization

The most difficult problem in hot gas desulfurization in Integrated Coal Gasification Combined Cycle (IGCC) is the pulverization of sulfur removal sorbents. Appropriate binders for hot gas sulfur removal sorbents can solve the pulverization problem. In this paper, six sorbents with binders of different argillaceous minerals were prepared by mechanical mixing method. Desulfurization behavior for hot gas desulfurization sorbents was investigated in a fixed-bed reactor. Result showed that sorbent NTKW2 with binder of clay had a better sulfidation performance. NTKW2 had a more stable performance than other sorbents in the continuous sulfidation-regeneration cycles. Sulfur capacity of sorbent remained the same in each cycle. The desulfurization efficiency and mechanical strength of NTKW2 were the best among the tested sorbents. The behavior of NTKW2 at different temperatures showed different performances, and the best reaction temperature was 550 °C. Higher heat stability, sulfur capacity and desulfurization efficiency were found on NTKW2 in six continuous sulfidation-regeneration cycles.

Screening of Zinc-Based Sorbents for Hot-Gas Desulfurization

Highly reactive and attrition-resistant ZnO-based sorbents that are suitable for bubbling fluidized-bed reactors can be produced using the spray-drying method. Most of the ZnO-based sorbents prepared here (ZAC-X, X = 18N−25N) satisfy the physical and chemical criteria for bubbling fluidized-bed application [spherical shape, average particle size, 90−110 µm; size distribution, 40−230 µm; bulk density, 0.9−1.0 g/mL; attrition index (AI), 40−80%; sulfur sorption capacity, 14−17 wt %; sorbent use, 70−80%]. The performance test of the ZAC-C sorbent at Korea Institute of Energy Research (KIER) with a bubbling fluidized-bed for 70 h also demonstrated that it had good sulfidation and regeneration performance (11 wt % sorption capacity and 52% sorbent use) as well as reasonable attrition resistance (1.1% attrition loss for 70 h).

New development of zinc-based sorbents for hot gas desulfurization

This paper introduced two new zinc-based sorbents for hot gas desulfurization, G-201 and G-202. Evaluation tests proved that both G-201 and G-202 sorbents had good performance in desulfurization. They could reduce H 2S concentration from about 10 g/m 3 in coal gas to less than 20 mg/m 3. In addition, the sulfur capacity of both sorbents increased with temperature rising. No decrease in sulfur capacity of G-201 occurred during 20-desulfurization/regeneration cycle tests, whose calculated value was 19.43–24.23 g/100 g sorbent. G-201 sorbent passed a 1500 h real hot gas desulfurization test in a fixed-bed PDU. No occurence of striping, attrition and sintering on the surface of used sorbents was found after the long-time test. The reactivity was stable and the sulfur capacity is 21.19 g/100 g sorbent after the 1500 h test.

04/00496 A study on regeneration of MnFeZnO supported upon −AI 2O 3 sorbents for hot gas desulfurization : Zhang, J. et al. Fuel Processing Technology, 2003, 84, (1–3). 217–227.

04/00496 A study on regeneration of MnFeZnO supported upon −AI 2O 3 sorbents for hot gas desulfurization : Zhang, J. et al. Fuel Processing Technology, 2003, 84, (1–3). 217–227.

Effect investigation of ZnO additive on MnFe/Al 2O 3 sorbents for hot gas desulfurization : Zhang, J. et al. Energy Conversion and Management, 2003, 44, (3), 357–367

Effect investigation of ZnO additive on MnFe/Al 2O 3 sorbents for hot gas desulfurization : Zhang, J. et al. Energy Conversion and Management, 2003, 44, (3), 357–367

A study on regeneration of Mn–Fe–Zn–O supported upon γ-Al 2O 3 sorbents for hot gas desulfurization

In this study, the regeneration conditions of Mn–Fe–Zn–O supported upon γ-Al 2O 3 sorbents for high-temperature desulfurization of fuel gases were investigated. Mn–Fe–Zn/γ-Al 2O 3 sorbents with Mn/Fe/Zn molar ratio of 2:1:0.2, AMFZ0.2, were prepared. Desulfurization and regeneration were carried out in a quartz fixed-bed reactor of 10-mm diameter. Sulfidation tests were performed at 650 °C using the gas mixture containing (mol) 0.3%H 2S–11.62%H 2–19.34%CO–6.85%CO 2–61.84%N 2 at SV=3000 h −1. Sulfur capacity of the fresh sorbent was about 5.3 gS/100 gSorbent. Regeneration parameters including temperature, concentration of oxygen, space velocity and steam content have been considered in order to obtain suitable regeneration conditions. The regeneration was performed at the following parameters—pressure: atmosphere, temperature: 600–750 °C, space velocity: 2000–3000 h −1 and gas composition (vol.%): 2–8 O 2, 4–10 H 2O with N 2 balance. Typical properties of the sorbents before and after regeneration were characterized using XRD, SEM, BET and ICP methods. The most suitable regeneration conditions were obtained including 700 °C of regeneration temperature, 6.0% of oxygen content and 8.0% of steam in the gas stream.

Effect investigation of ZnO additive on Mn–Fe/γ-Al 2O 3 sorbents for hot gas desulfurization

The effect of the molar ratio of Mn:Fe on Mn–Fe/γ-Al 2O 3 sorbent performance for hot gas desulfurization was studied in detail in this paper. The results showed that the ideal composition for preparation of Mn–Fe/γ-Al 2O 3 was a molar ratio of two, i.e. AMF2.0 sorbent, for the temperature range of 500–650 °C. The regenerated AMF2.0 sorbent desulfurization results showed that its reactivity was decreased when the reaction–regeneration cycles were more than seven at 700 °C, using 3.0 vol.% oxygen diluted with nitrogen as regeneration conditions. When a small amount of ZnO was added to the AMF2.0 sorbent, its performance in removal of H 2S was improved at the experimental conditions. The optimum composition for preparation of Mn–Fe–Zn/γ-Al 2O 3 was a 2:1:0.2 molar ratio of Mn:Fe:Zn, i.e. AMFZ0.2 sorbent. At the same regeneration conditions used for Mn–Fe/γ-Al 2O 3 sorbents, it was shown that the regenerated AMFZ0.2 sorbent had better desulfurization stability, which implied the AMFZ0.2 sorbent could be an ideal sorbent for removal of H 2S at high temperature for hot gas desulfurization.

Zeolite-Supported Metal Oxide Sorbents for Hot-Gas Desulfurization

This paper describes the results of the development of supported mixed-metal oxide sorbents for hot-gas desulfurization capable of withstanding multiple sulfidation/regeneration cycles at 871 °C (1600 °F). The sorbents consisted of various combinations of copper, molybdenum, and/or manganese oxides supported on a high silica-containing zeolite. These sorbents were tested in a fixed-bed reactor with simulated coal gas at 205 kPa (15 psig). The combination of all three metal oxides displayed synergism in enhancing efficiency for H2S removal and improved the crush strength on the pellets. Copper oxide was the most active component for reaction with H2S, while molybdenum and manganese oxides appeared to act as catalysts/promoters. During multicycle testing, this ternary metal oxide sorbent retained its reactivity and mechanical strength.

In Situ Fourier Transform Infrared Characterization of Sulfur Species Resulting from the Reaction of Water Vapor and Oxygen with Zinc Sulfide

Steam is utilized as a diluent in the regeneration of zinc-based hot gas desulfurization sorbents used in fuel gas cleanup. Therefore, the effect of water vapor on the interaction of zinc sulfide (ZnS) with oxygen at 823, 873, and 923 K was studied using Fourier transform infrared (FTIR) spectroscopy. When ZnS at 823 K was exposed to oxygen, sulfate (SO42-) was the most prominent species observed at oxygen pressures greater than 5 × 10-2 Torr while sulfite (SO32-) was the major species observed during the water vapor exposures. When ZnS at 823 K was exposed to an equimolar mixture of water vapor and oxygen, sulfite and sulfate were the most prominent products but the intensity of the sulfite peak was more than that of the sulfate. The sulfur species formed during the water vapor and oxygen exposures at both 873 and 923K were similar to those at 823 K, but the relative intensities of the peaks corresponding to these sulfur species were different. At all three temperatures, the presence of water vapor enhan...

97/05071 Development of advanced sorbents for hot gas desulfurization: Abbasian, J. et al. Proc. Annu. Int. Pittsburgh Coal Conf., 1996, 13, (1), 602–607

Integrated Gasification Combined-Cycle (IGCC) processes are among the leading contenders for the production of electricity from coal. Coal gas desulfurization to sufficiently low levels at elevated temperatures (T > 350 C) is now recognized as crucial to efficient and economic coal utilization in advanced IGCC processes. The implementation of hot coal gas desulfurization relies heavily on the development of regenerable sorbent materials which can efficiently reduce H{sub 2}S from several thousand ppmv levels down to a few ppmv over many cycles of sulfidation/regeneration. Zinc-based sorbents, such as zinc titanate, are currently the leading candidate sorbents, however, they have been shown to suffer from zinc volatilization at elevated temperatures leading to sorbent deterioration, increasing sorbent replacement costs, and the overall cost of hot gas cleanup. This paper discusses the results obtained in an ongoing investigation geared towards developing advanced mixed-metal oxide sorbents for desulfurization of coal-derived fuel gases in the temperature range of 350 to 550 C. The paper focuses on the study related to the development of durable sorbents and addresses thermodynamic considerations, sulfidation kinetics, regenerability, and long term durability of a number of novel sorbents.

97/05096 An innovative approach to the regeneration of hot gas desulfurization sorbents: White, J. et al. Proc. Annu. Int. Pittsburgh Coal Conf., 1996, 13, (1), 620–625

97/05096 An innovative approach to the regeneration of hot gas desulfurization sorbents: White, J. et al. Proc. Annu. Int. Pittsburgh Coal Conf., 1996, 13, (1), 620–625

97/03730 Development of regenerable copper-based sorbents for hot gas desulfurization

The implementation of hot gas cleanup systems heavily depends on the development of regenerable sorbents for removal of sulfur-containing species (mainly H{sub 2}S) from the fuel gas stream at elevated temperatures (i.e., >350 C) from levels of several thousand ppm down to a few ppm, over many sulfidation/regeneration cycles. In addition, these sorbents must have high sulfur capacity, good sulfidation kinetics, good mechanical strength, and good chemical and structural stability over multicycle testing. Zinc-based sorbents, such as zinc titanates, are the leading contenders for hot gas desulfurization. However, these sorbents have been shown to suffer from zinc volatilization at elevated temperatures, resulting in sorbent deterioration and losses through attrition, loss of reactivity, leading to increasing sorbent replacement costs and overall cost of electricity. Copper-based sorbents do not suffer from volatilization problems due to the high melting point of the metal. However, bulk copper oxide is easily reduced to elemental copper in a reducing fuel gas environment, which in turn results in insufficient level of desulfurization. Fortunately, the sorbent desulfurization performance can be greatly enhanced by combining copper oxide with other oxides to minimize or prevent sorbent reduction during the sulfidation stage. This paper reports on research conducted to-date on themore » development of copper-based sorbents for hot coal gas desulfurization. The results of packed-bed experiments carried out for the determination of optimum operating conditions and for the evaluation of the long-term durability and regenerability of selected copper chromite sorbents are presented and discussed.« less

Cu−Cr−O and Cu−Ce−O Regenerable Oxide Sorbents for Hot Gas Desulfurization

Binary Cu−Cr−O and Cu−Ce−O oxides were studied in this work as regenerable sorbents for high-temperature fuel gas desulfurization. CuO−Cr2O3 and CuO−CeO2 sorbents can remove H2S from simulated coal-derived fuel gas to less than 5−10 ppmv in the temperature range of 650−850 °C. The presence of stable CuCr2O4 in CuO−Cr2O3 solids retains some copper in the Cu2+ or Cu1+ oxidation state, which can account for the high H2S removal efficiency. In CuO−CeO2 sorbents, however, CuO is easily reduced to copper metal. Participation of reduced cerium oxide in sulfidation can explain the observed high desulfurization efficiency. TGA tests and XRD analysis indicate that sulfidation proceeds through partial initial reduction of the CuO−Cr2O3 sorbents: CuO → Cu/Cu2O → CuxS (x < 2). Reduction kinetics were studied in the TGA over temperature ranges of 550−850 and 350−850 °C, respectively, for the CuO−Cr2O3 and CuO−CeO2 materials. The sulfidation kinetic parameters were measured in the temperature range of 450−850 °C after prereduction of both sorbents. The sulfidation of metal copper in Cr2O3 and CeO2-x matrices is a fast reaction with low activation energy, 19.8 and 16.6 kJ/mol, respectively. Both types of sorbents can be fully regenerated with diluted air. The regeneration temperature affects the reaction pathway and the regenerability of the solid composition.

95/05273 Development and characterization of steam regenerable sorbents for hot gas desulfurization in coal gasification based combined cycle plant

95/05273 Development and characterization of steam regenerable sorbents for hot gas desulfurization in coal gasification based combined cycle plant

95/03323 Method for reducing sulfate formation during regeneration of hot-gas desulfurization sorbents

95/03323 Method for reducing sulfate formation during regeneration of hot-gas desulfurization sorbents

Hot gas desulfurization with vanadium-promoted zinc ferrite sorbents

The performance of zinc ferrite promoted with V 2 O 5 was investigated as a hot gas desulfurization sorbent. The sorbents were prepared by the incipient impregnation technique, and the vanadium loading and the calcination temperature were varied. The sorbents were tested in a packed-bed microreactor set-up for five sulfidation-regeneration cycles to investigate their breakthrough behaviour. Sulfidation was performed at 873–973 K with H 2 S-H 2 -H 2 O-N 2 mixtures, while regeneration was carried out at 923–973 K with O 2 -N 2 mixtures. The fresh, sulfided, and regenerated sorbents were characterized by atomic absorption spectroscopy, X-ray diffraction, surface area and porosity measurements. The results of the investigation indicated that the sorbents exhibited a more stable cyclic performance with higher vanadium loading, all vanadium-promoted sorbents reduced the H 2 S content of the gas to levels below the equilibrium level for zinc oxide, some H 2 S was chemisorbed by vanadium, and two-step calcination imparted structural stability to the sorbents.

Calcium silicates: A new class of highly regenerative sorbents for hot gas desulfurization

AbstractA study has been conducted on the utilization of calcium silicates and the silica supported lime as regenerative sorbents for desulfurization of hot combustion gases. Except for γ‐Ca2SiO4 and Ca3SiO5, all the calcium silicates and the silica supported calcium oxide are equally or more reactive than calcium oxide, and the regeneration rates of these sorbents are substantially higher than that of calcium oxide. There was no tendency of decaying of the reactivity after eight cycles of sorption and regeneration.