As well known in the petroleum industry and academia,Ni/ZnO catalysts have excellent desulfurization performance.However,the sulfur transfer mechanism of reactive adsorption desulfurization(RADS)that occurs on Ni/ZnO ...As well known in the petroleum industry and academia,Ni/ZnO catalysts have excellent desulfurization performance.However,the sulfur transfer mechanism of reactive adsorption desulfurization(RADS)that occurs on Ni/ZnO catalysts remains controversial.Herein,a periodic Ni nanorod supported on ZnO slab was built to represent the Ni/ZnO system,and density functional theory calculations were performed to study the sulfur transfer process and the role of H_(2)within the process.The results elucidate that the direct solid-state diffusion of S from Ni to interfacial oxygen vacancies(Ov)is more favorable than the hydrogenation of S to SH/H_(2)S on Ni and the subsequent H_(2)S desorption,and accordingly,H_(2)O is produced on Ni rather than on ZnO.Ab initio thermodynamics analysis shows that the hydrogen atmosphere applied in preparing Ni/ZnO catalysts greatly promotes the O_(v)formation on ZnO surface,which accounts for the presence of interfacial O_(v)in freshly prepared catalysts.Under RADS condition,hydrogenation of interfacial O atoms to form O-H groups facilitates the reverse spillover of these lattice O atoms from ZnO to Ni,accompanied with the interfacial O_(v)generation.In contrast to the classic S transfer mechanism via H_(2)S,the present work clearly demonstrates that the interfacial S transfer is a feasible reaction pathway in the RADS mechanism.More importantly,the existence of interfacial O_(v)is an essential prerequisite for this interfacial S diffusion,and H_(2)plays a key role in facilitating the O_(v)formation.展开更多
In the context of reactive adsorption desulfurization,the development of an efficient Ni/ZnO desulfurizer has attracted increasing attention.In the work reported here,a novel Ni/Mn-ZnO composite nanowire desulfurizer ...In the context of reactive adsorption desulfurization,the development of an efficient Ni/ZnO desulfurizer has attracted increasing attention.In the work reported here,a novel Ni/Mn-ZnO composite nanowire desulfurizer is designed on the basis of the catalytic theory of semiconductor metal oxides and the characteristics of one-dimensional nanomaterials.X-ray diffraction,scanning electron microscopy,N_(2) adsorption-desorption,and X-ray photoemission spectroscopy demonstrate that Mn doping changes the crystal structure and morphology of the Ni/ZnO desulfurizer,increases the number of quasi-free electrons in the ZnO,and promotes H_(2)S adsorption.The Ni/Mn-ZnO composite nanowire desulfurizer exhibits good desulfurization performance when used with gasoline as the raw material.展开更多
The reactive adsorption behavior of thiophene on the reduced Ni/ZnO sample was investigated by a combination of theoretical and experimental study.It is widely accepted that Ni is responsible for the sulfur-removal of...The reactive adsorption behavior of thiophene on the reduced Ni/ZnO sample was investigated by a combination of theoretical and experimental study.It is widely accepted that Ni is responsible for the sulfur-removal of thiophene to release S-free hydrocarbons.Such surface reaction was simulated by DFT method.It is demonstrated that thiophene is mainly adsorbed as p-complexation mode over metallic Ni.During desulfurization,the Se Ni bond is formed and the Ce S bond is thus split without pre-hydrogenation,resulting in the formation of Ni_(3)S_(2)phase and S-free C4 olefin which can be further saturated in the presence of H_(2).The S-transfer between Ni_(3)S_(2)and ZnO was monitored by in-situ XRD and STEM with EDS mapping.Two essential features were identified for efficient S-transfer,namely,1)the H_(2)atmosphere,and 2)the two phases are presented with close contact.Based on the acquired information,a general scenario of sulfur trail has been proposed for the desulfurization of thiophene on Ni/ZnO.展开更多
Novel Ni/ZnO–HZSM-5 adsorbents were synthesized by incipient wetness impregnation. The Ni/ZnO–HZSM-5 adsorbent can achieve deep desulfurization and olefin aromatization at the same time. Thiophene sulfur was removed...Novel Ni/ZnO–HZSM-5 adsorbents were synthesized by incipient wetness impregnation. The Ni/ZnO–HZSM-5 adsorbent can achieve deep desulfurization and olefin aromatization at the same time. Thiophene sulfur was removed from 495 to less than 10 ppm via reactive adsorption desulfurization(RADS). Olefins were also converted into aromatics. HZSM-5 did not only support adsorbents but also cooperated with active Ni sites to catalyze olefins into aromatic hydrocarbons. Aromatization of 1-pentene, 2-pentene, 2-methyl-2-butene, and 1-hexene on adsorbents was investigated. The adsorbents were characterized by the Brunauer–Emmett–Teller, X-ray diffraction, temperature-programmed reduction, and temperature-programmed desorption of ammonia and thermogravimetric analysis. The experimental results showed that strong acids on the adsorbent disappeared after HZSM-5 loaded active metal sites, and almost no coke was generated on adsorbents in RADS.展开更多
To better understand the nature of reactive adsorption of thiophene on Ni/ZnO adsorbent,the effect of ZnO textural structure on the desulfurization activity was investigated.ZnO materials were synthesized by low-tempe...To better understand the nature of reactive adsorption of thiophene on Ni/ZnO adsorbent,the effect of ZnO textural structure on the desulfurization activity was investigated.ZnO materials were synthesized by low-temperature solid-state reaction and the corresponding Ni/ZnO adsorbents were prepared by incipient impregnation method.The analysis results showed that the crystalline sizes of ZnO as-synthesized as well as the BET surface areas varied obviously with the calcination temperature.The activity evaluations indicated that the Ni/ZnO adsorbents prepared with ZnO possessed a favorable textural structure as active component exhibited good activity of removing thiophene.The evolutions of the main crystalline phases of Ni/ZnO adsorbents before and after reaction confirmed that ZnO played a crucial role in taking up S element and converting it into ZnS in the reactive adsorption process.It was concluded that ZnO with larger surface area and smaller crystal particles resulted in better desulfurization activity,which may be the main reason for the different activities of the Ni/ZnO adsorbents prepared with ZnO calcined at different temperatures.展开更多
To investigate the effect of texture structure on the desulfurization performance in the Ni/ZnO reactive adsorption desulfurization(RADS) system,two kinds of ZnO porous materials with rod-shaped morphology were synthe...To investigate the effect of texture structure on the desulfurization performance in the Ni/ZnO reactive adsorption desulfurization(RADS) system,two kinds of ZnO porous materials with rod-shaped morphology were synthesized and their structure was characterized by X-ray diffraction(XRD),scanning electron microscopy(SEM),transmission electron microscopy(TEM),and N2 adsorption/desorption.The formation mechanisms of hierarchical porous ZnO(ZnO with meso and macro pores) were also studied.Their application performance was evaluated in the RADS process over Ni/ZnO absorbent.Due to the difference in structure between the two kinds of ZnO,the two ZnO based adsorbents showed different desulfurization activity.展开更多
The reactive adsorption desulfurization of model gasoline was carried out on Ni/ZnO-HY adsorbent.The Ni/ZnO-HY adsorbent was characterized by N2adsorption-desorption test(BET),X-ray diffractometry(XRD),and temperature...The reactive adsorption desulfurization of model gasoline was carried out on Ni/ZnO-HY adsorbent.The Ni/ZnO-HY adsorbent was characterized by N2adsorption-desorption test(BET),X-ray diffractometry(XRD),and temperature-programmed reduction(TPR)analysis.The test results have demonstrated that HY-zeolite is a feasible support for Ni/ZnO components used in reactive adsorption desulfurization.The results of XRD and TPR analyses showed that most of nickel element was present as Ni2+species with only a small part existing as Ni3+species,and the Ni2+species had interactions with HY-zeolite.Under the conditions of this study,which specified a 50% ratio of HY-zeolite in the adsorbent,a Zn/Ni molar ratio of 10,and a reduction temperature of 400℃,the Ni/ZnO-HY adsorbent showed the best desulfurization performance.The sulfur capacity of Ni/ZnO-HY adsorbent could be recovered to 92.19% of the fresh one after being subjected to regeneration at 500℃,and could be maintained at 82.17% of the fresh one after 5 regeneration cycles.展开更多
The effect of mixed oxide support on the performance of Ni/ZnO in the reactive adsorption desulfurization(RADS) reaction was investigated in a fixed bed reactor by using thiophene as the sulfur-containing compound in ...The effect of mixed oxide support on the performance of Ni/ZnO in the reactive adsorption desulfurization(RADS) reaction was investigated in a fixed bed reactor by using thiophene as the sulfur-containing compound in the model gasoline. A series of oxide supports for Ni/ZnO were synthesized by the co-precipitation method and characterized by XRD, N_2-adsorption, TPR and NH_3-TPD techniques. It was found that the desulfurization capacity of Ni/ZnO was enhanced greatly when active components were supported on the proper mixed oxide. Ni/ZnO supported on oxides exhibited much higher desulfurization efficiency and sulfur adsorption capacity than the unsupported Ni/ZnO and the synthesized Ni/ZnO-SA adsorbent exhibited the highest efficiency for thiophene removal. The higher desulfurization activity and sulfur capacity of Ni/ZnO supported on SiO_2-Al_2O_3 with small particle size, high specific surface area and large pore volume could promote the high dispersion of active metal phase and the transfer of sulfur to ZnO with lower mass transfer resistance. γ-Al_2O_3 species could weaken the interaction of active phases and SiO_2 as well as could increase greatly the amount of weak acids. Therefore, these oxides could impose a great influence on the structure and chemical properties of the catalyst.展开更多
基金supported by the National Natural Science Foundation of China(22178388,21776315)the Taishan Scholars Program of Shandong Province(tsqn201909065)the Fundamental Research Funds for the Central Universities(19CX05001A).
文摘As well known in the petroleum industry and academia,Ni/ZnO catalysts have excellent desulfurization performance.However,the sulfur transfer mechanism of reactive adsorption desulfurization(RADS)that occurs on Ni/ZnO catalysts remains controversial.Herein,a periodic Ni nanorod supported on ZnO slab was built to represent the Ni/ZnO system,and density functional theory calculations were performed to study the sulfur transfer process and the role of H_(2)within the process.The results elucidate that the direct solid-state diffusion of S from Ni to interfacial oxygen vacancies(Ov)is more favorable than the hydrogenation of S to SH/H_(2)S on Ni and the subsequent H_(2)S desorption,and accordingly,H_(2)O is produced on Ni rather than on ZnO.Ab initio thermodynamics analysis shows that the hydrogen atmosphere applied in preparing Ni/ZnO catalysts greatly promotes the O_(v)formation on ZnO surface,which accounts for the presence of interfacial O_(v)in freshly prepared catalysts.Under RADS condition,hydrogenation of interfacial O atoms to form O-H groups facilitates the reverse spillover of these lattice O atoms from ZnO to Ni,accompanied with the interfacial O_(v)generation.In contrast to the classic S transfer mechanism via H_(2)S,the present work clearly demonstrates that the interfacial S transfer is a feasible reaction pathway in the RADS mechanism.More importantly,the existence of interfacial O_(v)is an essential prerequisite for this interfacial S diffusion,and H_(2)plays a key role in facilitating the O_(v)formation.
基金support from Project No. L2020013/L2020014 of the Liaoning Province Department of Educationsupported by the Talent Scientific Research Fund of LSHU (No.2021XJJL-020)
文摘In the context of reactive adsorption desulfurization,the development of an efficient Ni/ZnO desulfurizer has attracted increasing attention.In the work reported here,a novel Ni/Mn-ZnO composite nanowire desulfurizer is designed on the basis of the catalytic theory of semiconductor metal oxides and the characteristics of one-dimensional nanomaterials.X-ray diffraction,scanning electron microscopy,N_(2) adsorption-desorption,and X-ray photoemission spectroscopy demonstrate that Mn doping changes the crystal structure and morphology of the Ni/ZnO desulfurizer,increases the number of quasi-free electrons in the ZnO,and promotes H_(2)S adsorption.The Ni/Mn-ZnO composite nanowire desulfurizer exhibits good desulfurization performance when used with gasoline as the raw material.
基金financially supported by research grant from Sinopec(Fund No.118016-8)。
文摘The reactive adsorption behavior of thiophene on the reduced Ni/ZnO sample was investigated by a combination of theoretical and experimental study.It is widely accepted that Ni is responsible for the sulfur-removal of thiophene to release S-free hydrocarbons.Such surface reaction was simulated by DFT method.It is demonstrated that thiophene is mainly adsorbed as p-complexation mode over metallic Ni.During desulfurization,the Se Ni bond is formed and the Ce S bond is thus split without pre-hydrogenation,resulting in the formation of Ni_(3)S_(2)phase and S-free C4 olefin which can be further saturated in the presence of H_(2).The S-transfer between Ni_(3)S_(2)and ZnO was monitored by in-situ XRD and STEM with EDS mapping.Two essential features were identified for efficient S-transfer,namely,1)the H_(2)atmosphere,and 2)the two phases are presented with close contact.Based on the acquired information,a general scenario of sulfur trail has been proposed for the desulfurization of thiophene on Ni/ZnO.
文摘Novel Ni/ZnO–HZSM-5 adsorbents were synthesized by incipient wetness impregnation. The Ni/ZnO–HZSM-5 adsorbent can achieve deep desulfurization and olefin aromatization at the same time. Thiophene sulfur was removed from 495 to less than 10 ppm via reactive adsorption desulfurization(RADS). Olefins were also converted into aromatics. HZSM-5 did not only support adsorbents but also cooperated with active Ni sites to catalyze olefins into aromatic hydrocarbons. Aromatization of 1-pentene, 2-pentene, 2-methyl-2-butene, and 1-hexene on adsorbents was investigated. The adsorbents were characterized by the Brunauer–Emmett–Teller, X-ray diffraction, temperature-programmed reduction, and temperature-programmed desorption of ammonia and thermogravimetric analysis. The experimental results showed that strong acids on the adsorbent disappeared after HZSM-5 loaded active metal sites, and almost no coke was generated on adsorbents in RADS.
基金supported by National Key Fundamental Research development Plan ("973" Plan, No. 2010CB226905)the Postgraduate Innovation Fund of China University of petroleumthe Postgraduate Innovation Fund of China University of petroleum
文摘To better understand the nature of reactive adsorption of thiophene on Ni/ZnO adsorbent,the effect of ZnO textural structure on the desulfurization activity was investigated.ZnO materials were synthesized by low-temperature solid-state reaction and the corresponding Ni/ZnO adsorbents were prepared by incipient impregnation method.The analysis results showed that the crystalline sizes of ZnO as-synthesized as well as the BET surface areas varied obviously with the calcination temperature.The activity evaluations indicated that the Ni/ZnO adsorbents prepared with ZnO possessed a favorable textural structure as active component exhibited good activity of removing thiophene.The evolutions of the main crystalline phases of Ni/ZnO adsorbents before and after reaction confirmed that ZnO played a crucial role in taking up S element and converting it into ZnS in the reactive adsorption process.It was concluded that ZnO with larger surface area and smaller crystal particles resulted in better desulfurization activity,which may be the main reason for the different activities of the Ni/ZnO adsorbents prepared with ZnO calcined at different temperatures.
基金Financial support from the National Basic Research Program of China (No. 2010CB226905)the National Natural Science Foundation of China (Nos. 21176258, U1162203)the Specialized Research Fund for the Doctoral Program of Higher Education (20110133110002)
文摘To investigate the effect of texture structure on the desulfurization performance in the Ni/ZnO reactive adsorption desulfurization(RADS) system,two kinds of ZnO porous materials with rod-shaped morphology were synthesized and their structure was characterized by X-ray diffraction(XRD),scanning electron microscopy(SEM),transmission electron microscopy(TEM),and N2 adsorption/desorption.The formation mechanisms of hierarchical porous ZnO(ZnO with meso and macro pores) were also studied.Their application performance was evaluated in the RADS process over Ni/ZnO absorbent.Due to the difference in structure between the two kinds of ZnO,the two ZnO based adsorbents showed different desulfurization activity.
基金financially supported by the National Natural Science Foundation of China(No.21276086)the Opening Project of State Key Laboratory of Chemical Engineering of East China University of Science and Technology(No.SKL-ChE-11C04)
文摘The reactive adsorption desulfurization of model gasoline was carried out on Ni/ZnO-HY adsorbent.The Ni/ZnO-HY adsorbent was characterized by N2adsorption-desorption test(BET),X-ray diffractometry(XRD),and temperature-programmed reduction(TPR)analysis.The test results have demonstrated that HY-zeolite is a feasible support for Ni/ZnO components used in reactive adsorption desulfurization.The results of XRD and TPR analyses showed that most of nickel element was present as Ni2+species with only a small part existing as Ni3+species,and the Ni2+species had interactions with HY-zeolite.Under the conditions of this study,which specified a 50% ratio of HY-zeolite in the adsorbent,a Zn/Ni molar ratio of 10,and a reduction temperature of 400℃,the Ni/ZnO-HY adsorbent showed the best desulfurization performance.The sulfur capacity of Ni/ZnO-HY adsorbent could be recovered to 92.19% of the fresh one after being subjected to regeneration at 500℃,and could be maintained at 82.17% of the fresh one after 5 regeneration cycles.
基金financially supported by the National Natural Science Foundation of China(No.21276086)
文摘The effect of mixed oxide support on the performance of Ni/ZnO in the reactive adsorption desulfurization(RADS) reaction was investigated in a fixed bed reactor by using thiophene as the sulfur-containing compound in the model gasoline. A series of oxide supports for Ni/ZnO were synthesized by the co-precipitation method and characterized by XRD, N_2-adsorption, TPR and NH_3-TPD techniques. It was found that the desulfurization capacity of Ni/ZnO was enhanced greatly when active components were supported on the proper mixed oxide. Ni/ZnO supported on oxides exhibited much higher desulfurization efficiency and sulfur adsorption capacity than the unsupported Ni/ZnO and the synthesized Ni/ZnO-SA adsorbent exhibited the highest efficiency for thiophene removal. The higher desulfurization activity and sulfur capacity of Ni/ZnO supported on SiO_2-Al_2O_3 with small particle size, high specific surface area and large pore volume could promote the high dispersion of active metal phase and the transfer of sulfur to ZnO with lower mass transfer resistance. γ-Al_2O_3 species could weaken the interaction of active phases and SiO_2 as well as could increase greatly the amount of weak acids. Therefore, these oxides could impose a great influence on the structure and chemical properties of the catalyst.
