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Purposes The bimetallic modified Y zeolite is of great importance for the deep removal of thiophene in coking benzene. The influence of metal ion-exchange sequence on the desulfurization performance of zeolite is crucial. Methods A series of bimetallic modified sorbents were prepared by ion-exchange with Cu and Ce. The desulfurization performance of sorbents in thiophene-benzene solutions was evaluated by static adsorption experiments. The physical and chemical properties of sorbents were analyzed by XRD, Py-FTIR, XPS, H2-TPR, and N2 adsorption and desorption techniques. Findings The results show that metal ion-exchange sequence affects the relative crystallinity, ion-exchange degree, metal content, and L acid amount of sorbent. The correlations between the physical, chemical properties and the desulfurization performance of sorbent indicate that the higher the ion-exchange degree, the higher the desulfurization efficiency of sorbent. Meanwhile, the more Cu＋ and Ce4＋ in the sorbent, the more L acid sites formed and the higher its desulfurization efficiency. When Y zeolite is exchanged by Ce first and then Cu, the metal Ce affects the location of Cu and improves reduction performance of Cu. The desulfurization efficiency order of sorbents is CuCeY>CeCuY>Cu-CeY. The desulfurization efficiency of CuCeY is the highest, reaching 97.3%, and its relative crystallinity is the highest and ion-exchange degree is the largest. This work serves as a guide for the preparation of high efficiency desulfurization sorbents.

Pure benzene is an important chemical feedstock, and coking benzene is one of its sources. However, the industrialized coking benzene refining processes are not green and sustainable. To solve this problem, a green two-step process for the desulfurization of coking benzene with the advantages of easy operation, low environmental pollution and solid waste (sorbent/thiophene) recyclability was evaluated. The thiophene in coking benzene was first alkylated by the olefins present in it using a suitable AlCl3/silica gel catalyst to produce alkylthiophenes, which can be easily separated by distillation. The AlCl3/silica gel catalyst obtained by a novel green process was effective in catalyzing the alkylation of thiophene by 1-hexene with an efficiency of removing thiophene up to 94.2%. AlCl3 was grafted onto silica gel by reacting with hydroxyls on its surface, which could prevent the dissolution problem of AlCl3 in benzene. The residual thiophene with its concentration range of 100–1000 mg L−1 in benzene was then almost completely removed by adsorption using an ion-exchanged zeolite. The CeY zeolite sorbent showed excellent performance in deeply removing the residual thiophene in the benzene, in which the adsorption desulfurization over the CeY sorbent fits a Langmuir isotherm. The product met the requirements for a chemical feedstock, in that no thiophene was measured in the purified benzene by gas chromatography with a flame photometric detector. The CeY zeolite with adsorbed thiophene was used to prepare polythiophene–CeY composites by chemical oxidative polymerization using anhydrous FeCl3 as an oxidant at 0 °C. The decomposition temperature of the polythiophene–CeY composites is 480 °C, which is 60 °C higher than that of polythiophene. [ABSTRACT FROM AUTHOR]

Ce–Fe mixed metal oxide sorbentC2F3B850 was prepared byusing cerium oxide and red mud (an iron oxide waste from a steel company).The ability of C2F3B850 (CeO2/red mud = 0.85) was evaluatedover a fixed-bed reactor in a simulated coal-derived gas. It was foundthat the main active components of sorbent C2F3B850 were cerium andiron oxides, the addition of red mud in CeO2-based sorbentcould decrease sulfurization temperature, and 500 °C is the besttemperature for sulfurization in the range of 500–700 °C.After eight successive sulfurization–regeneration cycles overC2F3B850, the regenerated sorbent still performed well with no apparentdeterioration. The average breakthrough sulfur capacity correspondingto H2S concentrations below 50 ppmv is 9.97 (g S/100 gsorbent). Sorbent C2F3B850 during successive sulfurization–regenerationcycles was characterized by means of X-ray photoelectron spectroscopy,X-ray diffraction, and nitrogen adsorption–desorption techniques.The results reveal that the C2F3B850 sorbent with good durability,high efficiency, and high mechanical strength is suitable for desulfurizationof hot coal-based gas in the chemical industry. [ABSTRACT FROM AUTHOR]

The commercial NaY zeolite with the Si/Al ratio of 5:1 was selected and modified for researching the adsorptive removal of thiophene from benzene. The zeolite was ion-exchanged in Ce(NO3)3 solution and then calcined in muffle to prepare the CeY sorbent. The results show that it is a suitable method to prepare the sorbent removing thiophene from benzene that NaY zeolite is ion-exchanged by cerium in Ce(NO3)3 solution. The desulfurization efficiency of CeY sorbent increases obviously comparing with NaY zeolite. The effects of the calcination temperature, calcination time, concentration of Ce(NO3)3 solution, ion-exchange time, and ion-exchange times on the desulfurization capacity of CeY sorbent were also studied. The results show that the optimal CeY sorbent can be obtained when NaY zeolite is ion-exchanged in 0.5 mol/L Ce(NO3)3 solution at 100°C for 4 h, calcined at 700°C for 2 h, and repeated the above steps two times. The results of XRD and BET characterization indicate that those preparation conditions mainly influence on the crystallinity, specific surface area of CeY sorbent. The best CeY sorbent can remove thiophene to 136.8 mg/L from 550.0 mg/L in thiophene-benzene solution at ambient temperature and pressure with the agent-liquid ratio of 1:16 (g/mL). [ABSTRACT FROM AUTHOR]

• Cu/ZnO/Al 2 O 3 /ZrO 2 sorbent exhibited high activity and large sulfur capacity in reactive adsorption desulfurization. • The breakthrough adsorption capacity for thiophene could reach up to 36.24 mg/g. • The large number of Lewis acid sites on the sorbent surface facilitated the adsorption of thiophene and the breaking of C-S bonds. • The introduction of zirconium significantly improved the ability of the sorbent surface to activate and dissociate H 2. • Regulating the zirconium content not only improved the dispersion of the Cu species and the interaction between Cu-Zn, but also maintained the particle size of the Cu species during the reaction. The ultra-deep removal of thiophene from coke oven gas (COG) is critical for the conversion of COG to methane. Currently, Cu/ZnO/Al 2 O 3 is considered as a promising sorbent for thiophene removal; however, its desulfurization performance is currently unable to meet the requirements for industrial applications. Here, a zirconium modification strategy is proposed to overcome this problem, allowing zirconium loaded copper-based sorbents (Cu/ZnO/Al 2 O 3 /ZrO 2) with significantly improved thiophene removal performance and high activity to be obtained. Characterization results showed that zirconium improved both the dispersion of copper and the concentration of Lewis acid sites on the sorbent surface. A ZrO 2 concentration of 2 % resulted in stronger Cu-Zn interaction, and the dispersion of Cu on the surface of the sorbent reached its maximum value (49.20 %). Additionally, the Lewis acid strength was also maximized, which greatly improved the desulfurization activity and resulted in a breakthrough adsorption capacity of thiophene (Q b-thiophene) of 36.24 mg/g, which was about 17 % higher than that of the unmodified Cu/ZnO/Al 2 O 3 sorbent. These results demonstrate that the sulfur capacity of the sorbent can be increased by increasing the number of acidic sites on its surface, paving the way for ultra-deep thiophene removal in industrial applications. [ABSTRACT FROM AUTHOR]

[Display omitted] • Oxygen vacancy increases the ability to activate and dissociate H 2. • Oxygen vacancy greatly facilitates the adsorption of thiophene. • Calculation supports the beneficial role of oxygen vacancy in desulfurization. Cu/ZnO/CeO 2 sorbents with different oxygen vacancy contents were prepared by co-precipitation method and used for the removal of thiophene from coke oven gas. The desulfurization performance of sorbents was evaluated in a fixed-bed reactor. The structural characteristics of the sorbents were characterized by XRD, N 2 adsorption–desorption, XPS, Raman spectroscopy, H 2 -TPR, H 2 -TPD, SEM and TEM. The results confirmed the presence of oxygen vacancy sites in zinc oxide. And the oxygen vacancy could act as a key active site to facilitate thiophene sulfur capture as well as compensate for the acidity of the sorbent, thus allowing more thiophene to be adsorbed. Moreover, several potential active sites for adsorption of the produced H 2 S were calculated using Density Functional Theory (DFT), and the results reveal that the oxygen vacancy not only accelerated the cleavage of thiophene molecule, but also enhanced the ability for H 2 S capture. The sorbent with cerium content of 1% had the best desulfurization performance, and the breakthrough adsorption capacity for thiophene (Q b-thiophene) was 31.2 mg/g at 200 °C and under 5500 h−1 space velocity in simulated coke oven gas. [ABSTRACT FROM AUTHOR]

[Display omitted] • Heat treatment and ligand size adjustment could regulate Cu location in Y zeolite. • More copper could be located in supercages, resulting in more absorbed thiophene. • The Cu 10.74 Y 350 sample exhibits excellent desulfurization performance. Y zeolites modified with Cu are promising sorbents for adsorption desulfurization due to their cost-effectiveness. Only the supercage, which is larger than thiophene molecule, is the potential location of active sites for thiophene removal. However, numerous copper species cannot serve as effective active sites due to their inability to be located in the supercages. Based on this consideration, two strategies to regulate Cu location in Y zeolite to address the aforementioned challenges were explored. One is to adjust the molecular size of copper-ammonia ligands through pH value of cuprammonia solution, and the other is to prevent the migration of copper to small cages by heat treatment. The results showed that these two strategies could effectively regulate the location of copper active sites in Y zeolite. During heat treatment, Cu could transfer into supercages from sodalite cages at 350 °C. More effective copper would be targeted to be located in the supercages in the process of adjusting pH. For the best Cu 10.74 Y 350 sorbent, which was prepared at 350 °C under pH of 10.74, the Cu content in the supercages was the highest (25 %), and thus it has an excellent desulfurization efficiency of 82.3 %. [ABSTRACT FROM AUTHOR]

[Display omitted] • H 2 S in BFG could be adsorbed on Na-type FAU zeolite via two different ways. • H 2 S could be adsorbed on bridging hydroxyl groups of Na-type FAU zeolite. • H 2 S could interact with Na+ via base-acid interaction over FAU zeolite. • On Na+, H 2 S would be converted to S and further oxidized to SO 4 2− and S 2 O 3 2− by O 2. The desulfurization of blast furnace gas is crucial to meet the strict requirements for clean production of steel industry. However, the composition of blast furnace gas is complicated, and the gases of H 2 O, CO, CO 2 , and O 2 would significantly affect the desulfurization activity. Therefore, the desulfurization performance for H 2 S in simulated blast furnace gas by Na-type FAU zeolites with different Si/Al was investigated. The physicochemical properties of zeolite sorbents were measured, and their correlation with desulfurization performance was studied. Moreover, the adsorption mechanism of H 2 S was investigated. The breakthrough sulfur capacity improved with the increase of relative crystallinity, Na+ content, specific surface area, and the decrease of Si/Al ratio. The adsorption mechanism of H 2 S on Na-type FAU zeolite was proposed. One is the hydrogen bond interaction between the bridging hydroxyl groups and H 2 S, and the other one is the base-acid interaction between sodium ion and H 2 S. In blast furnace gas, when interacting with Na+, H 2 S would be transformed into S, which further oxidized into thiosulfate and sulfate by O 2. [ABSTRACT FROM AUTHOR]

Abstract: This paper studies the influence of the addition of Mo on the sulfidation performance of Fe-based sorbent supported on fly ash for hot coal gas desulfurization. Sorbent samples were prepared using physical mixing method with different Mo oxide content. The sulfidation experiments were carried out in the temperature range of 400–600°C. Gas compositions were analyzed using a GC. The structure and morphology of sorbent samples before and after sulfidation were examined by using SEM, XRD and compressive strength was also measured. The experimental results show that the fly ash supporter has some capability for sulfur removal from the hot coal gas. The addition of Mo may effectively improve the desulfurization efficiency and increase the compressive strength of iron-based sorbents. [Copyright &y& Elsevier]

Abstract: The coal poly-generation system for the production of alcohol and ether fuels as well as power is one of advanced coal utilization techniques. The team leaded by Professor Xie Kechang is carrying out the research on the poly-generation system to produce the syngas from the combination of gasified and pyrolyzed coal gas (dual gas resources) for the alcohol ether synthesis. Gas desulfurization is one of the key technologies for this system. The desulfurization matching with dual gas resources based poly-generation system for the production of alcohol and ether fuels as well as power is presented according to gas components, sulfur content, sulfur species and desulfurization accuracy in this technology. This matching desulfurization is classified into hot gas desulfurization, normal gas desulfurization, warm gas desulfurization and organic sulfur catalytic conversion. The preparation of H2S removal sorbents, organic sulfur hydrolysis catalyst and the evaluation of their activities involved in the system were investigated. The H2S removal efficiencies of the crude and fine desulfurization sorbents prepared for hot gas desulfurization are 90% and 99% at 500°C in simulating coal gas, and their sulfur capacities are 21.85wt.% and 24.91wt.%, respectively. The organic sulfur catalyst shows the high hydrolysis activity, and the hydrolysis conversion of COS is more than that of CS2 on the same catalyst. The research will provide necessary information for the matching desulfurization technology in the demonstration project on dual gas resources coal poly-generation system. [Copyright &y& Elsevier]

[Display omitted] • Heat treatment on precursor is a suitable way to regulate the Cu-Zn interaction. • Stronger Cu-Zn interaction could improve the desulfurization performance. • The breakthrough adsorption capacity for thiophene could reach up to 25.1 mg/g. The ultra-deep removal of thiophene is a necessary process for the coke oven gas (COG) to methane technology via methanation. It is usually carried out using copper-zinc (Cu-Zn) based sorbent, which was reported to has excellent desulfurization performance, however the effect of Cu-Zn interaction on the desulfurization activity of the sorbent is still need to be further understood. Here, the sorbent precursor was prepared via co-precipitation method, and it was treated at different temperatures to obtain a series of sorbents with different Cu-Zn interaction. The fixed bed reactor was used to evaluate the desulfurization performance, the XPS and H 2 -TPR was carried out to determine the Cu-Zn interaction in sorbents, and the N 2 adsorption, XRD, N 2 O adsorption, FT-IR were used to characterize the physical and chemical properties of samples. The results show that the Cu-Zn interaction could be effectively controlled by heat treatment temperature. At 300 °C, the sorbent precursor would be easily transformed into Cu-Zn solid solution, where the Cu-Zn interaction is strong, and the dispersion of Cu on the sorbent surface is maximized (16.0 %). Those greatly increase the desulfurization activity, and the breakthrough adsorption capacity for thiophene could reach up to 25.1 mg/g. At 250 °C, the temperature is not enough for the transforming of sorbent precursor into Cu-Zn solid solution, so that the breakthrough adsorption capacity for thiophene is only 12.4 mg/g. Whereas, when the temperature is higher than 350 °C, the Cu-Zn solid solution would be further transformed into CuO and ZnO, which significantly decreases the desulfurization activity. In addition, the density functional theory (DFT) calculation results provide further evidence that strong Cu-Zn interaction is beneficial to the desulfurization behavior of sorbent. This work provides both theoretical guidance for promoting the desulfurization performance of copper-based sorbents. [ABSTRACT FROM AUTHOR]

The deep removal of thiophene sulfur from coke oven gas (COG) is an important aspect for the subsequent production of COG to natural gas via methanation. In this process, copper-based sorbents exhibit excellent desulfurization activity. However, the activity of the sorbent depends largely on the interaction between Cu and Zn in the sorbent, which is often used to stabilize metal particles and regulate the activity and stability of the sorbent. Despite a large number of studies on metal-support interaction, there is still a lack of understanding of the effects of metal-support interaction of different strengths on the structure and performance of sorbents. In this work, Cu/ZnO sorbents with different strengths of metal-support interaction were successfully synthesized to elucidate the effect of the interaction between Cu and Zn on the performance of thiophene removal. The reconstruction process of the sorbent (different component ratios) changed the Cu Zn interaction. For weakly interacting sorbents, the reconstruction process enhanced the interaction between the two components, which is conducive to electron transfer and overall activity improvement. On the contrary, for sorbents with strong interaction, the reconstruction process was hindered. • Cu/ZnO is an excellent sorbent for thiophene removal from coke oven gas. • The interaction between Cu and ZnO could be cotrolled by Cu–Zn atomic ratio. • The CZ 1.00 sorbent with Cu–Zn atomic ratio of 1.00 has the best desulfurization performance. [ABSTRACT FROM AUTHOR]

Adsorption desulfurization processes employing zeolites as sorbents are considered to be prospective desulfurization methods owing to their cost-effectiveness. Y zeolites modified with Cu and Ce have excellent adsorption capacity and selectivity for adsorption desulfurization. However, the effect of using different metal precursors on the active sites of these sorbents and their adsorption desulfurization performance still remains ambiguous, which impedes the development of improved desulfurization adsorbents. Herein, Cu(NO 3) 2 , Cu(Ac) 2 , and CuSO 4 were selected as Cu precursors to prepare a series of CuCeY from CeY zeolite. Desulfurization experimental results indicate that outstanding breakthrough adsorption capacities for thiophene (ca. 6.25 mg·g−1) with benzene as the solvent were achieved by the CuCeY A. The interaction between the Cu Ce metals was beneficial for enhancing the electron transfer between Cu2++Ce3+/Ce4++Cu+. Moreover, using different copper precursors significantly changed the redox ability of the adsorbent surface. Changing the copper precursor also had a significant effect on the locations of Cu and Ce ions, and using Cu(Ac) 2 as a metal precursor facilitated the migration of Cu+ (53.6%) and cerium species (35.9%) to the supercage. In situ infrared characterization showed that the oligomerization of thiophene on CuCeY A was significantly restricted due to the lowest B acid content (11.85%) in the CuCeY A. [Display omitted] • A series of CuCeY have been prepared by a variety of Cu precursors. • CuCeY A prepared using Cu(Ac) 2 exhibits the excellent desulfurization performance. • Cu(Ac) 2 as precursor affected the chemical speciations and location of Cu and Ce. • Thiophene oligomerization can be significantly restricted on CuCeY A. [ABSTRACT FROM AUTHOR]

[Display omitted] • Ultra-deep removal of thiophene in coke oven gas can be achieved by Cu/ZnO sorbent. • The reactive adsorption process of thiophene over Cu/ZnO sorbent is clarified. • Parallel adsorption of thiophene on HCP site of Cu (1 1 1) is optimal. • Cu0 can dissociate H 2 into hydrogen atoms and cleave the C–S bond of thiophene. • Sulfur could transfer to ZnO and convert into ZnS without intermediate CuS. The reactive adsorption desulfurization mechanism of thiophene over Cu/ZnO sorbent in coke oven gas (COG) was established by a combination of theoretical and experimental study. The adsorption behavior of thiophene on Cu surface was studied by density functional theory (DFT) method. The C 4 hydrocarbons releases and sulfur migration over Cu/ZnO sorbent during the thiophene removal process were investigated by comparing with that over CuO, ZnO and CuO+ZnO (prepared by mechanical grinding of CuO and ZnO) sorbents. The results show that the parallel adsorption of thiophene on hexagonal closest packing (HCP) site of Cu (1 1 1) crystal face is the optimal adsorption mode. Cu0 nanoparticles in Cu/ZnO sorbent have two important roles: (1) adsorb and dissociate H 2 , and (2) cleave the C–S bond of thiophene. The sulfur after the cleavage of C–S bond could transfer directly to ZnO and eventually be converted into ZnS without the intermediate product CuS. During thiophene removal, C 4 H 6 and C 4 H 10 are generated over Cu/ZnO sorbent in the presence of H 2. ZnO in Cu/ZnO sorbent not only acts as an excellent sulfur accepter, but can greatly affect the adsorption properties by enhancing the spillover and storage of hydrogen atoms. Increasing the interaction between Cu0 nanoparticles and ZnO to enhance hydrogen spillover is an effective way to improve the thiophene reactive adsorption activity of Cu/ZnO. [ABSTRACT FROM AUTHOR]

A gas coal (B) was used to study the effect of volatiles on sulfur removal from a high organic-sulfur coking coal (A) from the perspective of mass transfer conditions. The mass transfer driving force and resistance of volatiles were analyzed in terms of fluidity development, permeability of coal plastic stage to gas flow, and volatile matter release. Carbonization using vertical and horizontal stacking modes of two coals were designed according to the release directions of volatiles during pyrolysis. Three pyrolysis temperatures (450, 475 and 510 ºC) were used to study mass transfer conditions. The semicokes were cut into pieces at fixed intervals along vertical and horizontal directions to determine the spatial sulfur distribution in semicoke. The gas coal volatiles helped the removal of sulfur within a limited distance that was related to the mass transfer conditions of volatiles, whereas permeability determined the mass transfer resistance of volatiles and their driving force was controlled by the amount and rate of volatile matter release. • Mass transfer conditions of volatiles vary with permeability of A and volatile evolution of B. • Volatiles of B remove sulfur within effective distances in vertical and horizontal directions. • Favorable mass transfer conditions extend release distance but reduce the reaction time. • Low permeability of plastic stage of A makes sulfur removal gentle but continuous. [ABSTRACT FROM AUTHOR]

Abstract: An integrated hot coal gas cleaning process is proposed with emphasis on simultaneous removal of multiple impurities including sulfur containing species, NO x precursors, mercury and tarry materials. Activated-char-supported sorbents were synthesized by gasifying Fe and Mo impregnated Chinese lignite coal in steam (15%, vol) at 1100K for 15min. Sulfur removal properties of the sorbent samples were examined by sulfidation experiments using simulated coal gases (with 4700ppmv H2S and 470ppmv COS) at a space velocity of 1000h−1 using a fixed-bed quartz reactor at the temperature range of 673–873K. The SEM with EDS and XRD were used to examine the physical and chemical changes in the sorbents during sulfidation. The active metal oxides components were dispersed in the char matrix as nano-size particles resulting in a high reactivity of the sorbents towards H2S and COS contained in coal gases. Under the conditions in this study, the sorbents can effectively remove H2S and COS from the simulated coal gases with high efficiency. Sulfur removal is influenced by the level of iron-loading. The presence of Mo along with Fe in the char-supported sorbents can significantly increase the desulfurization efficiency. [Copyright &y& Elsevier]

Abstract: Manganese oxide was loaded on the surface of γ-Al2O3 by sub-critical water impregnation using manganese acetate and manganese nitrate precursors to synthesize Mn(A) and Mn(N) sorbents for removing H2S from hot coal gas. Active component precursors present very obvious effect on the desulfurization capacity of sorbent. Mn(A, 11) sorbent with 11% Mn content in γ-Al2O3 maintains a desulfurization efficiency of close to 100% over 480min. However, it reduces to below 90% for Mn(N, 11) sorbent when the reaction lasts over 75min. The characterizing results of fresh and used sorbents from different precursors using AAS, SEM, BET, Raman, XAS and XPS techniques show that the acidity and alkalinity of active component precursor solution greatly influences the loading rate, valence state and dispersion of manganese on γ-Al2O3, which are the main properties for improving desulfurization performance of sorbents. The manganese loading rate of Mn(A) sorbent is much higher than Mn(N) sorbent. The better dispersion of manganese on γ-Al2O3 and the higher Mn2+ and Mn3+ contents on the surface of sorbent afford the high desulfurization activity of Mn(A). Moreover, Mn(A, 11) performs well in removing H2S from hot gas at 400°C after three desulfurization -regeneration cycles. [Copyright &y& Elsevier]

Abstract: Two iron oxide based sorbents, TG-1 and TG-F, with high desulfurization efficiency, were selected for simultaneous removal of H2S and Hg from simulated syngas. Our evaluation tests were carried out using a fixed bed reactor at different temperatures and in ambient atmosphere. The different activities for the simultaneous removal of H2S and Hg between TG-1 and TG-F or TG-1-S (denoted as such after uptake of H2S) were compared. The results show that the two iron oxide based sorbents can capture Hg effectively from simulated syngas. The preferred temperature for Hg removal using the TG-F and TG-1 sorbents are 60–120°C and 100–140°C, respectively. The Hg absorption capacity of TG-1 is higher than that of TG-F under the same conditions. CO and H2 in the feed gas have negligible effect on the efficiency of Hg removal. H2S is favoured for the removal of Hg over iron-based sorbents and it was found that the influence of H2S concentration on the Hg capacity of the TG-1 and TG-F sorbents are different. It is found that the main active components of the two sorbents during the reaction are different. After several desulfurization cycles, the TG-1-S sorbent has a high efficiency for Hg removal from the simulated syngas. [Copyright &y& Elsevier]

Series sorbents of Cu, Zn, Ni, Ce and Ag metal components supported on γ-AlO carrier for removing thiophene from benzene were prepared by conventional and ultrasound-assisted incipient-wetness impregnation method. The static adsorption experiments were carried out in the thiophene-benzene solution with thiophene concentration of 500 mg/L. The results show that the desulfurization activity of all γ-AlO sorbents modified by different metal components obviously increase, among which the sorbent modified by silver nitrate has the best performance. The active components of sorbents from Cu, Zn, Ni, Ce nitrates loaded on γ-AlO carrier are their oxides. Besides AgO, the products of silver nitrate thermal decomposition in sorbent prepared still have Ag and Ag-O-Al species. The assistant ultrasound in the process of sorbent preparation can not only shorten the impregnation time, but also enrich the pore structure of sorbent and improve the size and distribution of the Ag species, which is favorable to the removal of thiophene from benzene. The desulfurization capacity of sorbent changes with the Ag content loaded. The sorbent with 15 % quality content of Ag prepared by ultrasound-assisted impregnation method has the highest desulfurization efficiency. It could reduce the thiophene concentration to 1.7 mg/L from 500 mg/L at room temperature and ambient pressure, with the desulfurization efficiency of more than 99 %, when the ratio of sorbent to solution was 1:4 (g/mL). [ABSTRACT FROM AUTHOR]

The ultra-deep removal of thiophene to 0.1 ppmv level is necessary for coke oven gas to methane process. NaY zeolite was reported to have this potential, and acid sites in NaY play an important role on its desulfurization performance. Based on this situation, sorbents with different types and strengths of acids were prepared by modifying NaY in ammonium nitrate and citric acid solutions. Their desulfurization behaviors in simulated coke oven gas were evaluated by fixed bed. The results show that both ammonium nitrate and citric acid modification on NaY are beneficial to the breakthrough adsorption capacity of thiophene (Q b-thiophene). The NaY after modified in 0.10 mol/L citric acid solution has the highest Q b-thiophene at 100 °C. Ammonium nitrate modification could significantly increase medium-strong Bronsted acid in NaY, whereas citric acid modification mainly increases weak Lewis acid. On medium-strong Bronsted acid sites, thiophene polymerization reaction would occur easily, which would result in the obvious decrease of Q b-thiophene from 71.31 to 35.3 mg/g due to the acid sites covering and micropores blocking by thiophene oligomer. The increase of Lewis acid is conducive to desulfurization. Moreover, on Lewis acid site, the temperature region for thiophene removal is wider than that on Bronsted acid. Unlabelled Image • Sorbents for ultra-deep desulfurization was developed by improving acid sites. • NH 4 NO 3 modification increase medium-strong Bronsted acid in NaY. • Citric acid modification mainly increases weak Lewis acid in NaY. • L acid promotes thiophene adsorption, whereas B acid promotes thiophene polymerization. [ABSTRACT FROM AUTHOR]

• Different pre-desulfurization processes have different effects on mineral and sulfur removals from raw coal. • The sulfur removal by stepwise treatment was more effective than the individual treatment. • Stepwise treatment could remove the inorganic and organic sulfur from raw coal simultaneously. • The combination of flotation, acid washing and ultrasonication should be considered for the utilization of high sulfur coals. To achieve the utilization of high sulfur coals efficiently and economically, the effects of different pre-desulfurization processes including flotation, acid washing, ultrasonication and stepwise treatment on sulfur removal and changes of sulfur forms in a high sulfur coal, sulfur transformation behavior during pyrolysis and sulfur distribution in char were investigated. Flotation removed almost all the sulfate and partial pyrite from the raw coal, while ultrasonication was more effective in removing some low molecular-weight organic sulfur together with weakening the C-S bond in some sulfur species. The process of HCl-HF-HNO 3 and stepwise treatment reduced the ash content and sulfur content to a larger extent, with ultrasonication after flotation and acid treatment having the highest sulfur removal from raw coal. The sulfur forms on coal surface were more modified after different pre-desulfurization processes, together with different sulfur transformations during pyrolysis. The accumulated amount of sulfur-containing gases during pyrolysis of coals after stepwise treatment, in particular of coals treated by the combination of flotation, acid washing and ultrasonication, generated the highest amount of sulfur-containing gases. For the utilization of high sulfur coals, in particular, of high organic-sulfur coals, the above-mentioned treatment of combination of traditional flotation technique and organic sulfur removal process should be considered, which could remove the inorganic sulfur and organic sulfur simultaneously, and release the most sulfur-containing gases during pyrolysis. Besides, it would be helpful to choose the utilization methods based on the sulfur species in raw coal, and the effect of pre-desulfurization process on sulfur transformation behavior. [ABSTRACT FROM AUTHOR]