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The ultra-deep removal of thiophene is essential for the conversion of coke oven gas to methane and metal modified Y zeolite has excellent thiophene adsorption capacity. The effects of temperature on chemisorption between metal modified Y zeolite and thiophene and the reductive gases in coke oven gas on the thiophene adsorption performance still remains ambiguous. To address the aforementioned aims, series of NaMY (M = Ce, Ni, Zn and Ag) were prepared via ion-exchanged with Na+ of NaY, and two comparable sets of thiophene adsorption evaluation were conducted in a fixed bed reactor: (1) NaY and NaMY were evaluated at different temperatures in simulated coke oven gas, and (2) NaCeY was evaluated in N2 and different reductive atmospheres. The results show that NaNiY, NaZnY and NaAgY could adsorb thiophene via π-complexation, however, NaCeY mainly through S-Ce bond. Π complexation becomes weak above 150 °C, and the strength of S-Ce bond varies little when the temperature rises to 250 °C. Compared with that of other sorbents, the breakthrough adsorption capacity for thiophene (Qb-thiophene) of NaAgY reaches the highest 144 mg/g at 100 °C, but decreases sharply when temperature rises to 200 °C. NaCeY has relatively low variation in Qb-thiophene from 100 °C to 200 °C. Moreover, Ce(IV) in NaCeY is more favorable for thiophene adsorption than Ce(III) in coke oven gas and the presence of H2 and CO would reduce the desulfurization activity of NaCeY. For the industrial utilization of thiophene ultra-deep removal, NaAgY has an excellent potential below 150 °C, while NaCeY with more Ce(IV) has a good prospect at 150–250 °C. [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]

NaY and Na13X zeolites were modified by different modification manners including H+ modification, metal ion modification (Cu2+, Ni2+, or Ce3+), and H+ modification followed by metal ion modification to investigate their deep desulfurization behavior in gasoline. The sorbents were characterized by X-ray diffraction, FTIR of chemisorbed pyridine, N2 adsorption, and scanning electron microscope (SEM). The desulfurization performance of these sorbents was evaluated in model gasoline containing thiophene and cyclohexane with thiophene concentration of 500 mg/L, and the results were analyzed to investigate the effect of preparation methods on adsorption desulfurization behavior. The result indicates that H+ modification or metal ion modification could all improve the desulfurization performance of both NaY and Na13X zeolites, except for Na13X modified by Cu2+ and Ni2+. For Cu2+ or Ni2+ ion exchanging, the crystal structure of Na13X would be destroyed, resulting in a much lower desulfurization efficiency than that of the parent Na13X. The desulfurization efficiency of sorbents prepared via H+ modification followed by metal ion modification is higher than that of sorbents prepared by single H+ modification or single metal ion modification, because the former is more conducive to improve the content of metal elements on the sorbents than the latter. In addition, the increase of the specific surface area and pore volume of the sorbents would directly lead to the improvement of desulfurization performance of the sorbents. Compared with Na13X, the H+ modification on NaY zeolite can significantly enhance the desulfurization performance of the sorbents. Among those prepared sorbents, the CuHY has the highest desulfurization efficiency. The influence of thiophene concentration (100–1000 mg/L) on desulfurization efficiency of CuHY sorbent was evaluated. The results indicate that the desulfurization efficiency of CuHY sorbent is nearly 100% at room temperature, when the thiophene concentration is lower than 300 mg/L. Moreover, its desulfurization behavior could be described by Langmuir isothermal equation. Graphic abstract. [ABSTRACT FROM AUTHOR]

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]

[Display omitted] • The adsorption of sorbent for thiophene was accompanied by S-Ag and π complexation. • Ag-O-Si is the main active center for adsorption of thiophenic compounds. • Charge density of sulfur atom affects S-Ag bond between thiophenic compounds and Ag. Zeolites and some mesoporous materials modified by Ag possess excellent desulfurization performances toward the adsorption of thiophenic compounds. However, Ag in Ag-based sorbents has different forms, and the interactions between different forms of silver and thiophene still require further studies. In this paper, pure silica SBA-15 and MCM-41 mesoporous materials with weak acidity were loaded with Ag from the silver ammonia solution to form Ag/SBA-15 and Ag/MCM-41 sorbents. By comparing the desulfurization efficiencies of the sorbents in the simulated solution of thiophene-cyclohexane, thiophene-benzene, tetrahydrothiophene-cyclohexane and tetrahydrothiophene-benzene, it is found that the adsorption of sorbent for thiophene was accompanied by S-Ag and π complexation, and the adsorption performances of thiophene by the sorbents were greatly affected by benzene. The XPS results show that most Ag in Ag/SBA-15 and Ag/MCM-41 sorbents was metallic Ag, and some Ag strongly interacting with the carrier led to the formation of Ag-O-Si bonds as the main active center of thiophenic compounds. In addition, the sulfur atomic mulliken charges (e-) of different thiopheic compounds (thiophene, tetrahydrothiophene, methylthiophene) will affect the interactions between active components Ag and thiophene sulfur compounds. The desulfurization efficiencies of the sorbents in thiophene-cyclohexane, 2-methylthiophene-cyclohexane, and 3-methylthiophene-cyclohexane showed that the decrease in mulliken charges (e-) of sulfur atoms facilitated the S-Ag bond interaction between the sulfur atom of thiophenic compounds and active component in the sorbent. In conclusion, to obtain the Ag-based sorbent with good adsorption performance for thiophenic compounds, the carrier should contain a certain content of silicon hydroxyl and the suitable pore structure. During the preparation of SBA-15 and MCM-41 mesoporous materials modified by Ag, the Ag-O-Si bonds are more easily formed when silver ammonia interacts with the silicon hydroxyl group on the surface of the carrier. The suitable pore size can inhibit agglomerate to form metallic Ag during the calcination process. These conclusions will provide theoretical guidance for the preparation of silver-based sorbents for thiophene. [ABSTRACT FROM AUTHOR]

Abstract: AlCl3/silica gel catalysts were prepared by inclosed grafting method in the autoclave and their catalytic activities for alkylation reaction of thiophene with olefins in benzene were studied. The gas chromatograph and chromatography–mass spectroscopy were used to quantitatively determine the thiophene in benzene and qualitatively measure the reaction products, respectively. XPS, SEM, EDX and N2 adsorption techniques were used to characterize the physical and chemical properties of catalyst samples. The results show that AlCl3 can be effectively anchored by reacting with the silanol groups on silica gel surface to form the Si x (OH) y − a O a AlCl(3− a) species and the prepared AlCl3/silica gel catalyst possesses the significant activity for the alkylation reaction of thiophene and olefin. The preparation conditions, such as mass ratio of AlCl3/silica gel support, grafting temperature and time, and thermal treatment temperature of silica gel, have an important role on the content and distribution of active component over silica gel support, and thus affect the catalytic activity. The optimum preparation conditions of AlCl3/silica gel catalyst are that AlCl3 is grafted on silica gel support, which has been thermally treated at 400°C for 3h, and at 180°C for 4h with the mass ratio of 0.20 for AlCl3/silica gel support. The loading ratio of AlCl3 on silica gel can reach about 64wt.% and the optimal conversion rate of thiophene in benzene is 94.23% when the ratio of liquid to catalyst is 20mL/g. [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 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] • 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]

[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 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]