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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]

• 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]