High-temperature Desulfurization Sorbents Research Articles

Tea Garden Lateritic Soil as a High-Temperature Desulfurization Sorbent: Effect of Oxygen on Regeneration Process

The lateritic soils collected from a tea garden were used to explore the regeneration process using different O2 contents for high-temperature desulfurization. The desulfurization and regeneration experiments were carried out using a fixed-bed reactor at 500°C and the gaseous mixture composed of 1% H2S, 25% CO, 15% H2, and balance N2 for the desulfurization process. Experimental results showed that the regenerability is better when the air was used as a regeneration gas and the regeneration time is shortened. Multiple regeneration experiments indicated that lateritic soils can be regenerated by passing air and can thus be reused many times and its regeneration efficiency is slightly better than that regenerated by 1% O2. The sulfur capacity after air desulfurization/regeneration cycles was examined by elemental analysis with a value ranging from 1.40% to 1.49%, and residual sulfur was detected with a value of 0.12% after the diluted 1% O2 regeneration. No sulfur was detected for the regenerated lateritic soil after air regeneration. From NMR structural identification, the 6-coordinated octahedral structure of Al and trioctahedral coordinated Si are the major Al-containing and Si-containing compounds. Broad shoulder peaks were detected after regeneration process that may be associated with the formation of aluminosilicate and further reduces the dispersion of iron on the surface of lateritic soils.

Dynamics of Bed for Regeneration of Cerium Oxide High-Temperature Coal Gas Desulfurization Sorbent

The dynamic behavior of bed for regeneration of cerium oxide high temperature gas desulfurization sorbent under the atmosphere of O2 was investigated in the fixed bed micro-reactor. O2 concentration during the regeneration can be detected by an oxygen analyzer, and the sulfur content of sorbent in the bed was test using sulfur analyzer. The effects of O2 concentration, regeneration temperature on the dynamic behavior of bed for regeneration of CeO2 desulfurization sorbent were discussed. According to the experimental results, the length and movement speed of regeneration zone are calculated. The results showed that the increase of O2 concentration in inlet gas obviously improves the movement speed of regeneration zone in bed for CeO2 desulfurization sorbent, and the increase of regeneration temperature can decreased the length of the regeneration zone and improved the movement speed of the regeneration zone. The increase of regeneration temperature had a better effect on the improvement of bed utilization of sorbent than that of O2 concentration.

H2S 제거를 위한 고온건식 탈황제의 연구 및 기술개발동향

청정석탄기술 중 하나인 석탄가스화 복합발전기술의 이론적 고찰 및 주요단위공정에 사용되는 고온건식 탈황제의 연구 및 기술개발 동향을 조사하였다. 고온건식 탈황제 개발의 중요한 요소는 반응성, 내구성 및 내마모성에 있으며, 탈황제 종류는 칼슘계, 아연계, 망간계, 철계, 구리계 등이 있다. 현재 고온건식 탈황제의 경우 선진국을 중심으로 아연계 탈황제 제조기술이 가장 상용화 단계에 있으며, 국내에서도 다양한 지지체를 사용하여 가격이 저렴하고 성능이 우수한 아연계 및 비아연계 고온건식 탈황제의 상용화를 위한 연구개발이 진행 중에 있다. Theoretical reviews of integrated gasification combined cycle one of the clean coal technologies and trends in the study and technology development for high temperature desulfurization sorbents were investigated. Reactivity, durability and abrasion resistance is an important key for development of high temperature desulfurization sorbents, the kind of things include calcium, zinc, manganese, iron and copper-based sorbents. Current status of high temperature desulfurization sorbents, manufacturing techniques of zinc-based sorbent in advanced countries has commercialized. In case of Korea, various research studies are underway to commercialize the Zn and non Zn-based high temperature desulfurization sorbents to cheaper and superior capability using various supports.

Regeneration Kinetics Study of Fe<sub>2</sub>O<sub>3</sub> Desulfurization Sorbents in SO<sub>2</sub> Atmosphere

The influences of the regeneration temperature and SO2volume fraction on regeneration kinetics behavior of Fe2O3 sorbent as a high-temperature desulfurization sorbent were researched by TGA (Thermos gravimetric analyzer) in this work. The main regeneration product of iron oxide desulfurization sorbent was Fe2O3 and sulfur in SO2 atmosphere which has an important practical significance for pollution control of H2Sandrecycleofsulfur. The results indicate that Fe2O3 desulfurization sorbent was completely regenerated at temperature of 725-775 °C and the higher regeneration temperature and volume fraction of SO2 is benefit to improve regeneration reaction rate. The regeneration reaction of Fe2O3 sorbent in SO2atmosphere can be first order reaction obtained by the equivalent grain model, and the controlling process of regeneration reaction is change from the chemical reaction control to the diffusion control in the whole regeneration process. The chemical reaction apparent activation energy and the corresponding frequency factor of chemical reaction are 145.31 kJ/mol and 0.0063 m/s, respectively. And that of diffusion are 50.73 kJ/mol and 4.38×10-3 m2/s, respectively.

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.

Comments on “Ceria−Zirconia High-Temperature Desulfurization Sorbents”

ADVERTISEMENT RETURN TO ISSUEPREVCorrespondenceNEXTComments on “Ceria−Zirconia High-Temperature Desulfurization Sorbents”M. Hartman and O. TrnkaView Author Information Institute of Chemical Process Fundamentals, Academy of Sciences of the Czech Republic, 165 02 Prague 6Suchdol, Czech Republic Cite this: Ind. Eng. Chem. Res. 2006, 45, 4, 1548–1549Publication Date (Web):January 13, 2006Publication History Published online13 January 2006Published inissue 1 February 2006https://doi.org/10.1021/ie058078hCopyright © 2006 American Chemical SocietyRIGHTS & PERMISSIONSArticle Views206Altmetric-Citations3LEARN ABOUT THESE METRICSArticle Views are the COUNTER-compliant sum of full text article downloads since November 2008 (both PDF and HTML) across all institutions and individuals. These metrics are regularly updated to reflect usage leading up to the last few days.Citations are the number of other articles citing this article, calculated by Crossref and updated daily. Find more information about Crossref citation counts.The Altmetric Attention Score is a quantitative measure of the attention that a research article has received online. Clicking on the donut icon will load a page at altmetric.com with additional details about the score and the social media presence for the given article. Find more information on the Altmetric Attention Score and how the score is calculated. Share Add toView InAdd Full Text with ReferenceAdd Description ExportRISCitationCitation and abstractCitation and referencesMore Options Share onFacebookTwitterWechatLinked InReddit PDF (23 KB) Get e-AlertsSUBJECTS:Coal,Desulfurization,Equilibrium,Oxides,Power Get e-Alerts

Effect of Pore Size Distribution of Calcium Oxide High-Temperature Desulfurization Sorbent on Its Sulfurization and Consecutive Oxidative Decomposition

CaS formed from the CaO sorbent during desulfurization in coal gasifiers must be converted to CaSO4 before disposal. CaS is mainly decomposed to CaO and SO2, and then the CaO is converted to CaSO4 ...

High temperature removal of hydrogen sulfide using an N-150 sorbent

In this study, an N-150 sorbent was used as a high temperature desulfurization sorbent for the removal of hydrogen sulfide from coal gas in a fixed bed reactor. The results indicate that the N-150 sorbent could be used for H 2S removal in the tested temperature ranges. Regeneration test also reveals that utilization of the N-150 sorbent maintains up to 85% compared to the fresh sorbent. No significant degeneration occurs on the N-150 sorbent. In addition, various concentrations of H 2S, H 2 and CO were also considered in the performance test of the N-150 sorbent. Except for H 2S, H 2 and CO act the important roles in the high temperature desulfurization. By increasing the H 2 concentration, the sulfur capacity of the sorbent decreases and an adverse result is observed in the case of increasing CO concentration. This can be explained via water-shift reaction. On the basis of the instrument analysis, X-ray powder diffraction determination and SEM images with EDS spectrum characterization, residual sulfur is found in the regenerated N-150 sorbent and this sulfur species is sulfate which resulted by incomplete regeneration. The sulfate formation and sintering effect are major reasons to cause activity loss in the sulfidation/regeneration cycles.

Role of H2O in Oxidation of Spent High-Temperature Desulfurization Sorbent Fe2O3 and CuO in the Presence of O2

To develop an easily regenerable high-temperature desulfurization sorbent, the oxidation of spent Fe2O3 and CuO sorbents in the presence of O2 and H2O was studied: The effect of H2O on the oxidation of the spent Fe2O3 and CuO was examined using a temperature-programmed reduction technique and isotopic H218O. In this study, it was found that H2O directly contributed to the oxidation of the spent metal oxides in the presence of O2. The oxidation of the spent metal oxides (containing metal sulfide MexSy) in the presence of 10% H2O and 10% O2 could be explained by the following two reactions: MexSy + (z + 2y)H2O ⇔ MexOz + SO2 + (z + y)H2 and (z + 2y)H2 + {(z + 2y)/2}O2 ⇒ (z + 2y)H2O.

Role of TiO2 on Oxidative Regeneration of Spent High-Temperature Desulfurization Sorbent ZnO−TiO2

To develop an easily regenerable high-temperature desulfurization sorbent, the role of TiO2 in the course of oxidative regeneration of ZnO−TiO2 in the presence of O2 and H2O was studied. ZnO−TiO2 and ZnO were prepared by a precipitation method using aqueous solutions of Zn(NO3)2, Ti(SO4)2, TiO2 sol, and NH3. The oxidative regeneration character of the spent ZnO−TiO2 and ZnO was examined using a temperature-programmed reaction technique and isotopic H218O. It was found that TiO2 accelerated both the reaction between ZnS and O2 and the reaction between ZnS and H2O and also accelerated the oxidative regeneration of ZnS in the presence of both O2 and H2O. Furthermore, the acceleration in the presence of both O2 and H2O could be explained by an activation of H2O over TiO2 and spillover of the activated H2O species.

Reduced cerium oxide as an efficient and durable high temperature desulfurization sorbent

Cerium oxide has been studied as a candidate second-generation sorbent for high-temperature gas desulfurization. Although CeO 2 will react with H 2S, the reaction thermodynamics do not permit H 2S target levels of about 20 ppmv to be reached. However, at high temperature in a strongly reducing gas, CeO 2 is reduced to a non-stoichiometric oxide, CeO n ( n<2), which is superior to CeO 2 in removing H 2S. The reduction and sulfidation reactions were studied in a fixed-bed reactor as a function of temperature, pressure, and feed gas composition and flow rate. With feed rates corresponding to about 1.4 s reactor residence time, the H 2S concentration was reduced to less than 10 ppmv at temperatures as high as 850°C and to near 1 ppmv at 700°C. Effectively complete conversion of CeO n to Ce 2O 2S was achieved, and the sorbent showed excellent durability through 25 reduction–sulfidation–regeneration cycles. CeO n produced in a separate pre-reduction step was marginally more effective than when the reduction–sulfidation reactions occurred simultaneously. However, both approaches were capable of reducing the H 2S to below the 20-ppmv target level. The cerium sorbent is most effective at temperatures and in reducing gas compositions where first-generation zinc-based sorbents cannot be used.

Role of H2O in Oxidative Regeneration of ZnS Formed from High-Temperature Desulfurization ZnO Sorbent

To develop an easily regenerable zinc oxide high-temperature desulfurization sorbent, the role of H2O in the course of oxidative regeneration of zinc sulfide in the presence of O2 were studied using ZnO without support material as a sorbent. Oxidative regeneration of ZnS in the presence of water vapor was examined using TPR technique and H218O. From this study, the following results were obtained: ZnS was converted to SO2 and H2 by H2O in the absence of O2 at high temperature (> ca. 600 °C); in the first step in the oxidative regeneration, ZnS predominantly reacted with H2O more than O2; the SO2 formed from ZnS contained oxygen from H2O. From the experimental results, it was found that the oxidative regeneration of ZnS in the presence of H2O and O2 can be expressed by the following two equations: ZnS + 3H2O ⇔ ZnO + SO2 + 3H2; 3H2 + 3/2O2 ⇒ 3H2O. In the absence of H2O or in the case of very low value of H2O/O2 concentration ratio, the following reaction also occurred: ZnS + 3/2O2 ⇒ ZnO + SO2

00/01107 Modification of ZnO-TiO2 high-temperature desulfurization sorbent by ZrO2 addition

00/01107 Modification of ZnO-TiO2 high-temperature desulfurization sorbent by ZrO2 addition

High temperature gas desulfurization with elemental sulfur production

Preliminary results on the use of cerium oxide as a high-temperature desulfurization sorbent are presented. The primary advantage of cerium over current zinc-based sorbents is the potential to produce elemental sulfur during the regeneration phase of the process. Although CeO 2 is less effective for H 2S removal during sulfidation, the sulfided product, Ce 2O 2S, will react with SO 2 to produce elemental sulfur directly. Rapid and complete regeneration is possible over the range of 500 to 700°C, and only elemental sulfur is formed. Elemental sulfur concentrations (considered as S 2) as large as 20 mol% have been produced in the regeneration product. The sorbent has been subjected to ten sulfidation–regeneration cycles using a laboratory-scale fixed-bed reactor with negligible activity loss. Effectively complete conversion of CeO 2 to Ce 2O 2S during sulfidation and subsequent regeneration to CeO 2 was achieved in each cycle. A two-stage desulfurization process using CeO 2 for bulk H 2S removal followed by a zinc sorbent polishing step has been proposed to meet specifications of the integrated gasification combined cycle (IGCC) process. Economic comparison with a single-stage desulfurization process using zinc sorbent followed by elemental sulfur recovery using the direct sulfur recovery process (DSRP) shows that the two-stage cerium process may be less costly if the cerium sorbent is sufficiently durable.

Modification of ZnO−TiO2 High-Temperature Desulfurization Sorbent by ZrO2 Addition

To develop a highly reactive and easily regenerable zinc oxide high-temperature desulfurization sorbent, a modification of ZnO−TiO2 by addition of ZrO2 was studied. The metal oxides ZnO−TiO2−ZrO2 were prepared by a coprecipitation method: the amount of ZnO was a fixed 50 mol % of the sample. In this study, it was found that the addition of 5 or 10 mol % ZrO2 to 50 mol % ZnO−50 mol % TiO2 greatly improved the reactivity for H2S removal. Furthermore, the addition of ZrO2 improved its regenerability: the temperature for the regeneration of the sample was decreased to ca. 40 °C in the absence of H2O and ca. 75 °C in the presence of 10% H2O by the addition of 10% ZrO2.

Preparation of Macroporous Lime from Natural Lime by Swelling Method with Acetic Acid for High-Temperature Desulfurization

To develop a highly active calcium oxide high-temperature desulfurization sorbent, a method of preparation of macroporous calcium oxides from lime was studied. This method is composed of two steps: swelling of the lime and calcination of the swelled sample. Swelling occurred when lime was exposed to the vapor of acetic acid. The swelling resulted from calcium acetate formation in the sample. The swelling rate was at a maximum in the presence of acetic acid and depressed by the presence of water vapor. The swelled sample was converted to macroporous calcium oxide by heating to 850 °C. The reactivity of the macroporous calcium oxide for the removal of SO2 or H2S in the presence of H2O vapor was higher than that of the calcined raw limestone. In particular, its SO2 removal capacity and the oxidative character of CaS to CaSO4 and CaO were greatly improved by this swelling method. These characteristics were also compared with those of a sample prepared from limestone by this swelling method.

Elemental sulfur production during the regeneration of iron oxide high-temperature desulfurization sorbent

The production of elemental sulfur instead of SO 2 during the regeneration of high temperature desulfurization sorbents will improve the efficiency of advanced power generation processes such as the integrated gasification combined cycle (IGCC). While much research is directed at developing zinc-based sorbents because of the favorable thermodynamics of the ZnO–H 2S reaction, SO 2 is the inevitable product from ZnS regeneration. Iron-based sorbents, although less efficient for H 2S removal, permit significant amounts of elemental sulfur to be formed during regeneration. A laboratory-scale fixed-bed reactor has been used to study the regeneration of FeS in steam-oxygen mixtures. The experimental results are interpreted on the basis of four simultaneous reactions. Oxygen reacts rapidly with FeS to produce SO 2 and Fe 2O 3. Steam reacts to give Fe 3O 4 and H 2S. Elemental sulfur is formed by the reaction between H 2S and SO 2, and additional O 2 is consumed in converting Fe 3O 4 to Fe 2O 3. The maximum yield of elemental sulfur, approximately 75% of theoretical, was achieved using a large H 2O-to-O 2 ratio (200-to-1) at the lowest feasible regeneration temperature (600°C), and using a small regeneration gas feed rate.

Novel Preparation Method of Macroporous Lime from Limestone for High-Temperature Desulfurization

In order to develop a highly active calcium oxide high-temperature desulfurization sorbent, macroporous calcium oxides were directly prepared from limestone. This method is composed of two steps: swelling of the limestone in the gas phase followed by drying and calcination of the swelled samples. The swelling was found when limestone was exposed to a vapor of aqueous acetic acid. The swelling of the sample resulted from an increase of calcium acetate formation in the sample. It was then converted to macroporous calcium oxides by heating the sample to 850 °C. The reactivity of the macroporous calcium oxide for the removal of SO2 or H2S under coexisting H2O vapor was higher than that of the calcined raw limestone. In particular, its SO2 removal capacity and oxidative character of CaS to CaSO4 and CaO were greatly improved by the swelling method.

Desulfurization of Hot Coal-Derived Fuel Gases with Manganese-Based Regenerable Sorbents. 2. Regeneration and Multicycle Tests

In a previous paper, the reduction and sulfidation thermodynamic and kinetic characteristics of four manganese-based high-temperature desulfurization sorbents were investigated. A formulation, FORM4-A, which consisted of manganese carbonate, alundum, and bentonite exhibited the best combination of capacity and reactivity; whereas, FORM1-A, which consisted of Mn ore, alundum, and dextrin exhibited the best combination of strength, capacity, and reactivity. In this paper the thermodynamic feasibility of regeneration is discussed. The kinetics of regeneration of sulfided (loaded) pellets with air is studied in the 800-1000°C temperature range. Repeated cycling of the leading sorbent formulation (FORM4-A) was then conducted in a thermogravimetric apparatus (TGA), up to five consecutive cycles

Stability of Zinc Oxide High-Temperature Desulfurization Sorbents for Reduction

ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTStability of Zinc Oxide High-Temperature Desulfurization Sorbents for ReductionEiji Sasaoka, Shigeru Hirano, Shigeaki Kasaoka, and Yusaku SakataCite this: Energy Fuels 1994, 8, 3, 763–769Publication Date (Print):May 1, 1994Publication History Published online1 May 2002Published inissue 1 May 1994https://doi.org/10.1021/ef00045a033RIGHTS & PERMISSIONSArticle Views768Altmetric-Citations40LEARN ABOUT THESE METRICSArticle Views are the COUNTER-compliant sum of full text article downloads since November 2008 (both PDF and HTML) across all institutions and individuals. These metrics are regularly updated to reflect usage leading up to the last few days.Citations are the number of other articles citing this article, calculated by Crossref and updated daily. Find more information about Crossref citation counts.The Altmetric Attention Score is a quantitative measure of the attention that a research article has received online. Clicking on the donut icon will load a page at altmetric.com with additional details about the score and the social media presence for the given article. Find more information on the Altmetric Attention Score and how the score is calculated. Share Add toView InAdd Full Text with ReferenceAdd Description ExportRISCitationCitation and abstractCitation and referencesMore Options Share onFacebookTwitterWechatLinked InReddit PDF (2 MB) Get e-Alerts Get e-Alerts