Steam reforming(SR)of fossil methane is already a well-known,documented and established expertise in the industrial sector as it accounts for the vast majority of global hydrogen production.From a sustainable developm...Steam reforming(SR)of fossil methane is already a well-known,documented and established expertise in the industrial sector as it accounts for the vast majority of global hydrogen production.From a sustainable development perspective,hydrogen production by SR of biomass-derived feedstock represents a promising alternative that could help to lower the carbon footprint of the traditional process.In this regard,bio-alcohols such as methanol,ethanol or glycerol are among the attractive candidates that could serve as green hydrogen carriers as they decompose at relatively low temperatures in the presence of water compared to methane,allowing for improved H_(2)yields.However,significant challenges remain regarding the activity and stability of nickel-based catalysts,which are most widely used in alcohol SR processes due to their affordability and ability to break C–C,O–H and C–H bonds,yet are prone to rapid deactivation primarily caused by coke deposition and metal particle sintering.In this state-of-the-art review,a portfolio of strategies to improve the performance of Ni-based catalysts used in alcohol SR processes is unfolded with the intent of pinpointing the critical issues in catalyst development.Close examination of the literature reveals that the efforts tackling these recurring issues can be directed at the active metal,either by tuning Ni dispersion and Ni-support interactions or by targeting synergistic effects in bimetallic systems,while others focus on the support,either by modifying acid-base character,oxygen mobility,or by embedding Ni in specific crystallographic structures.This review provides a very useful tool to orient future work in catalyst development.展开更多
A series of Ni/SBA-15 catalysts with Ni contents ranging from 5wt% to 20wt% as well as 10wt%Ni/10wt%CexZr1-xO2/SBA-15 (x=0, 0.5, 1) were prepared. The structures of the catalysts were characterized using XRD, TPR, T...A series of Ni/SBA-15 catalysts with Ni contents ranging from 5wt% to 20wt% as well as 10wt%Ni/10wt%CexZr1-xO2/SBA-15 (x=0, 0.5, 1) were prepared. The structures of the catalysts were characterized using XRD, TPR, TEM and BET techniques. The catalytic activities of the catalysts for steam reforming of methane were evaluated in a continuous flow microreactor. The results indicated that both the Ni/SBA-15 and the Ni/CexZr1-xO2/SBA-15 catalysts had good catalytic activities at at- mospheric pressure. The 10wt%Ni/SBA-15 catalyst exhibited excellent stability at 800 ℃ for time on stream of 740 h. After the reaction, carbon deposits were not formed on the surface of the catalyst. There existed a regular hexagonal mesoporous structure in the Ni/SBA-15 and the Ni/CexZr1-xO2/SBA-15 catalysts. The nickel species and the CexZr1-xO2 component were all confined in the SBA-15 mesopores. The CexZr1-xO2 could promote dispersion of the nickel species in the Ni/CexZr1-xO2/SBA-15 catalysts.展开更多
The hydrogenation of petroleum resin(PR)is an effective process to prepare high value-added hydrogenated PR(HPR).However,the preparation of non-noble metal-based catalysts with high catalytic activity for PR hydrogena...The hydrogenation of petroleum resin(PR)is an effective process to prepare high value-added hydrogenated PR(HPR).However,the preparation of non-noble metal-based catalysts with high catalytic activity for PR hydrogenation still remains a challenge.Herein,a La promoted Ni-based catalyst is reported through the thermal reduction of quaternary Ni La Mg Al-layered double hydroxides(Ni La Mg Al-LDHs).The incorporation of La is beneficial to the reduction and stability of Ni particles with reduced particle size,and the increased alkalinity effectively mitigates the breakage of molecular chains of PR.As a result,the La promoted Ni-based catalyst exhibits high catalytic activity and excellent stability for PR hydrogenation.A hydrogenation degree of 95.4%and 96.1%can be achieved for HC_(5)PR and HC_(9) PR with less reduced softening point,respectively.Notably,the hydrogenation degree still maintains at 92.7%even after 100 hours’reaction,much better than that without La incorporation or prepared using conventional impregnation method.展开更多
A series of Ni/SBA-15 catalysts with 5wt% to 15wt% Ni content as well as a series of 12.5%Ni/Cu/SBA-15 catalysts with 1% to 10% copper content were prepared by the impregnation method. The catalytic performance for pa...A series of Ni/SBA-15 catalysts with 5wt% to 15wt% Ni content as well as a series of 12.5%Ni/Cu/SBA-15 catalysts with 1% to 10% copper content were prepared by the impregnation method. The catalytic performance for partial oxidation of methane was investigated in a continuous flow microreactor under atmospheric pressure. The textural and chemical properties of the catalysts were characterized by XRD, TEM, BET and Hz-TPR techniques. The results indicated that the catalysts modified with Cu promoter showed better performance than those without modification. For the 12.5%Ni/2.5%/Cu/SBA-15 catalyst, at 850 ℃ the conversion of CH4 reached 97.9% and the selectivity of CO and H2 reached 98.0% and 96.0%, respectively. In XRD patterns of the Ni/Cu/SBA-15 catalyst with 7.5 to 10% Cu contents there were CuO characteristic peaks beside NiO characteristic peaks. The mesoporous structure of SBA-15 was retained in all of the catalysts. TPR analysis of the catalysts revealed that a strong interaction between Ni, Cu promoter and SBA-15 support may be existed. This interaction enhanced significantly the redox properties of the catalysts resulting in the higher catalytic activity.展开更多
Generating sufficient strains on metal surfaces are highly challenging owing to that most metals can deform plastically to relax the strains on the surfaces.In this work,we developed a facile but highly efficient stac...Generating sufficient strains on metal surfaces are highly challenging owing to that most metals can deform plastically to relax the strains on the surfaces.In this work,we developed a facile but highly efficient stacked deposition strategy to in situ activation and reconstruction of NiO/NiOOH on Ni matrix,following with the migration of Fe ions to NiOOH.The Fe sites on the Ni/NiO/NiOOH facilitate the formation of the stable*OH oxygenated intermediates,and the Ni matrix in the catalyst provides the catalyst excellent stability.The oxygen evolution reaction(OER)performance of the stacked NiFe-5 with compressive strain displays the strengthened binding to oxygenated intermediates and superior OER activity,the ultralow overpotentials of 162 versus reversible hydrogen electrode at 10 mA cm^(-2).On the other hand,the Ni-5 without the incorporation of Fe has shown an outstanding hydrogen evolution reaction(HER)activity,affording an overpotential of 47 mV at 10 mA cm^(-2).The NiFe-5‖Ni-5 enables the overall water splitting at a voltage of 1.508 V to achieve 20 mA cm^(-2) with remarkable durability.The stacked deposition strategy improves binding strength of Ni-based catalysts to oxygenated intermediates via generating compressive strain,causing high catalytic activities on OER and HER.展开更多
A series of Ni/SBA-15 catalysts with Ni contents ranging from 5 wt% to 15 wt%, as well as another series of 10%Ni/MgO/SBA-15 catalysts, in which the range of the MgO content was from 1 wt% to 7 wt%, were prepared, and...A series of Ni/SBA-15 catalysts with Ni contents ranging from 5 wt% to 15 wt%, as well as another series of 10%Ni/MgO/SBA-15 catalysts, in which the range of the MgO content was from 1 wt% to 7 wt%, were prepared, and their catalytic performances for the reaction of combined steam and carbon dioxide reforming of methane were investigated in a continuous flow microreactor. The structures of the catalysts were characterized using the XRD, H2-TPR and CO2-TPD techniques. The results indicated that the CO selectivity for this reaction was very close to 100%, and the H2/CO ratio of the product gas could be controlled by changing the H2O/CO2 molar ratio of the feed gas. The simultaneous and plentiful existing of steam and CO2 had a significant influence on the catalytic performance of the 10%Ni/SBA-15 catalyst without modification. After reacting at 850 °C for 120 h over this catalyst, the CH4 conversion dropped from 98% to 85%, and the CO2 conversion decreased from 86% to 53%. However, the 10%Ni/3%MgO/SBA-15 catalyst exhibited a much better catalytic performance, and after reacting for 620 h, the CO2 conversion over this catalyst dropped from 92% to around 77%, while the CH4 conversion was not decreased. Oxidation of the Ni0 species as well as carbon deposition during the reaction were the main reasons for the deactivation of the catalyst without modification. On the other hand, modification by the MgO promoter improved the dispersion of the Ni0 species, and enhanced the CO2 adsorption affinity which in turn depressed the occurring of carbon deposition, and thus retarded the deactivation process.展开更多
A series of Ni/SBA-15 catalysts with Ni contents from 7.5 wt% to 15 wt% were prepared by impregnation method.The effect of O2 and H2O on the combined reforming of the simulated biogas to syngas was investigated in a c...A series of Ni/SBA-15 catalysts with Ni contents from 7.5 wt% to 15 wt% were prepared by impregnation method.The effect of O2 and H2O on the combined reforming of the simulated biogas to syngas was investigated in a continuous flow fixed-bed micro-reactor.The stability of the catalyst was tested at 800 ?C.The results indicated that 10wt%Ni/SBA-15 catalyst exhibited the highest catalytic activities for the combined reforming of the simulated biogas to syngas.Under the reaction conditions of the feed gas molar ratios CH4/CO2/O2/H2O = 2/1/0.6/0.6,GHSV = 24000 ml·gcat^-1·h^-1 and the reaction temperature T = 800 ℃,the conversions of CH4 and CO2 were 92.8% and 76.3%,respectively,and the yields of CO and H2 were 99.0% and 82.0%,respectively.The catalytic activities of the catalyst did not decrease obviously after 100 h reaction time on stream.展开更多
Highly active and selective Ni-based catalysts for partial oxidation of methane (POM) to syngas (CO/H,) have been studied and developed. Spectroscopic characterization by XRD, XPS, EPR, etc. demonstrated that under th...Highly active and selective Ni-based catalysts for partial oxidation of methane (POM) to syngas (CO/H,) have been studied and developed. Spectroscopic characterization by XRD, XPS, EPR, etc. demonstrated that under the POM reaction conditions, the Ni-components of the catalysts investigated were reduced and enriched on the surface to form metallic Ni0-phase. A comparative study of the first series of transition-metals showed that only Ni and Co have a high POM activity and selectivity, whereas the others (including Mn, Fe, Cu, etc. ) give mainly complete combustion products, Co, and H2O. The results favor the following viewpoints: the PoM activity is related with the rapidly changeable valence transitionmetal sites, M0/M2+ (e. g. Ni0/Ni2+ ), on the surface of the functioning catalysts;the transition-metal sites in zero-valence state seem to be responsible for the activation and dehydrogenation of methane by homolytic splitting of its C-H bonds on these sites. and the nature of rapidly changeable valence of the active sties is requisite for activation and rapid conversion of dioxygen.展开更多
In this study,Ni catalysts supported on Pr-doped Ce O_(2) are studied for the CO_(2) methanation reaction and the effect of Pr doping on the physicochemical properties and the catalytic performance is thoroughly evalu...In this study,Ni catalysts supported on Pr-doped Ce O_(2) are studied for the CO_(2) methanation reaction and the effect of Pr doping on the physicochemical properties and the catalytic performance is thoroughly evaluated.It is shown,that Pr^(3+)ions can substitute Ce^(4+)ones in the support lattice,thereby introducing a high population of oxygen vacancies,which act as active sites for CO_(2) chemisorption.Pr doping can also act to reduce the crystallite size of metallic Ni,thus promoting the active metal dispersion.Catalytic performance evaluation evidences the promoting effect of low Pr loadings(5 at%and 10 at%)towards a higher catalytic activity and lower CO_(2) activation energy.On the other hand,higher Pr contents negate the positive effects on the catalytic activity by decreasing the oxygen vacancy population,thereby creating a volcano-type trend towards an optimum amount of aliovalent substitution.展开更多
A series of Ni/SBA-15 catalysts with Ni contents from 5 wt%–20 wt%and CaO-12.5%Ni/SBA-15 catalysts with CaO contents from 1.4 wt%– 9.8 wt%have been prepared.The structure of the catalysts was characterized using X-r...A series of Ni/SBA-15 catalysts with Ni contents from 5 wt%–20 wt%and CaO-12.5%Ni/SBA-15 catalysts with CaO contents from 1.4 wt%– 9.8 wt%have been prepared.The structure of the catalysts was characterized using X-ray diffraction(XRD),N2 adsorption-desorption,transmission electron microscopy(TEM)and X-ray photoelectron spectroscopy(XPS).The performance of catalytic steam reforming of the poplar leaves to the hydrogen-rich syngas was tested in a fixed-bed reactor.The results indicate that the 7.0wt%CaO-12.5wt%Ni/SBA-15 catalyst exhibits the best performance for the catalytic steam reforming of poplar leaves to hydrogen-rich syngas.The ratio of H2:CO can reach ca 5:1 in the hydrogen-rich syngas.The yield of H2 can reach 273.30 mL/g(poplar leaves).In the CaO-Ni/SBA-15 catalyst,Ni active component mainly fills the role of catalytic steam reforming of the poplar leaves,and CaO active component mainly plays the role as water-gas shift and CO2 sorbent.展开更多
Ni-based catalysts are widely investigated non-noble metal-based systems for CO_(2)methanation.However,their industrial application is still limited due to lower activity at low-temperature and catalyst deactivation.I...Ni-based catalysts are widely investigated non-noble metal-based systems for CO_(2)methanation.However,their industrial application is still limited due to lower activity at low-temperature and catalyst deactivation.Incorporating a second metal such as Ru and Fe is considered as a successful strategy to overcome these challenges through alloy formation or the synergies provided by the interplay of two adjacent metallic sites.Nonetheless,their promotional effect on the CO_(2)methanation mechanism under similar conditions has not been reported yet.In this work,Fe and Ru-promoted Ni/ZrO_(2)catalysts were investigated to evaluate their promotional effect on the mechanism.The Ni/Fe ratio was first optimized and a CO_(2)conversion rate of 37.7 mmolCO_(2)/(molNi+Fes)and 96.3%CH^(4)selectivity was obtained over the Ni_(0.8)Fe_(0.2)/ZrO_(2)catalyst.In comparison with Ni_(0.8)Fe_(0.2)/ZrO_(2),Ni_(0.8)Ru_(0.2)/ZrO_(2)prepared with the same composition showed higher activity and stability in CO_(2)methanation.Characterization results indicate alloys formation and H spillover for Ni_(0.8)Ru_(0.2)/ZrO_(2)to be responsible for promotion.Besides,in situ DRIFTS studies evidenced the occurrence of both CO_(2)dissociative and associative pathways over Ni_(0.8)Ru_(0.2)/ZrO_(2)catalyst,while solely the CO_(2)associative pathway occurred for Ni_(0.8)Fe_(0.2)/ZrO_(2)展开更多
CeO2-promoted Ni/Al2O3-ZrO2 (Ni/Al2O3-ZrO2-CeO2) catalysts were prepared by a direct sol-gel process with citric acid as gelling agent. The catalysts used for the methane reforming with CO2 was studied by infrared s...CeO2-promoted Ni/Al2O3-ZrO2 (Ni/Al2O3-ZrO2-CeO2) catalysts were prepared by a direct sol-gel process with citric acid as gelling agent. The catalysts used for the methane reforming with CO2 was studied by infrared spectroscopy (IR), thermal gravimetric analysis (TGA), microscopic analysis, X-ray diffraction (XRD) and temperature-programmed reduction (TPR). The catalytic performance for CO2 reforming of methane to synthesis gas was investigated in a continuous-flow micro-reactor under atmospheric pressure. TGA, IR, XRD and microscopic analysis show that the catalysts prepared by the direct sol-gel process consist of Ni particles with a nanostructure of around 5 nm and an amorphous-phase composite oxide support. There exists a chemical interaction between metallic Ni particles and supports, which makes metallic Ni well dispersed, highly active and stable. The addition of CeO2 effectively improves the dispersion and the stability of Ni particles of the prepared catalysts, and enhances the adsorption of CO2 on the surface of catalysts. The catalytic tests for methane reforming with CO2 to synthesis gas show that the Ni/Al2O3-ZrO2-CeO2 catalysts show excellent activity and stability compared with the Ni/Al2O3 catalyst. The excellent catalytic activity and stability of the Ni/Al2O3-ZrO2-CeO2 are attributed to the highly, uniformly and stably dispersed small metallic Ni particles, the high reducibility of the Ni oxides and the interaction between metallic Ni particles and the composite oxide supports.展开更多
The cognition of active sites in the Ni-based catalysts plays a vital role and remains a huge challenge in improving catalytic performance of low temperature CO_(2) dry reforming of methane(LTDRM).In this work,typical...The cognition of active sites in the Ni-based catalysts plays a vital role and remains a huge challenge in improving catalytic performance of low temperature CO_(2) dry reforming of methane(LTDRM).In this work,typical catalysts of SiO_(2) and γ-Al_(2)O_(3) supported Ni and Ni-Ce were designed and prepared.Importantly,the difference in the chemical speciations of active sites on the Ni-based catalysts is revealed by advanced characterizations and further estimates respective catalytic performance for LTDRM.Results show that larger[Ni0-]particles mixed with[Ni-O-Sin])species on the Ni/SiO_(2)(R)make CH_(4) excessive decomposition,leading to poor activity and stability.Once the Ce species is doped,however,superior activity(59.0%CH_(4) and 59.8%CO_(2) conversions),stability and high H_(2)/CO ratio(0.96)at 600℃ can be achieved on the Ni-Ce/SiO_(2)(R),in comparison with other catalysts and even reported studies.The improved performance can be ascribed to the formation of integral([Ni0_(n))]-[CeⅢ-□-CeⅢ])species on the Ni-Ce/SiO_(2)(R)catalyst,containing highly dispersed[Ni]particles and rich oxygen vacancies,which can synergistically establish a new stable balance between gasification of carbon species and CO_(2) dissocia-tion.With respect to Ni-Ce/γ-Al_(2)O_(3)(R),the Ni and Ce precursors are easily captured by extra-framework Al_(n)-OH groups and further form stable isolated([Ni0_(n))]-[Ni-O-Al_(n)])and[CeⅢ-O-Al_(n)]species.In such a case,both of them preferentially accelerate CO_(2) adsorption and dissociation,causing more car-bon deposition due to the disproportionation of superfuous CO product.This deep distinguishment of chemical speciations of active sites can guide us to further develop new efficient Ni-based catalysts for LTDRM in the future.展开更多
MnOx-promoted Ni-based catalyst supported by ZnO was developed to selectively hydrogenate glucose into polyols in water at 523 K with a yield of 64.9%. Using glucose, sorbitol, glycerol and LA as the rawmaterials, the...MnOx-promoted Ni-based catalyst supported by ZnO was developed to selectively hydrogenate glucose into polyols in water at 523 K with a yield of 64.9%. Using glucose, sorbitol, glycerol and LA as the rawmaterials, the roles of nickel, ZnO and MnOx were investigated. The results show that nickel provided a new pathway of glucose to sorbitol and played an important role in the hydrogenation of C3 intermediates to 1,2-propanediol(1,2-PDO). The high yield of 1, 2-PDO was attributed to effective C–C bond cleavage performance of ZnO support promoted by MnOx. ZnO and MnOx contribute to the conversion of glycerol to lactic acid(LA) and LA to 1, 2-PDO, respectively. A concise pathway for hydrogenation of glucose over Ni-based catalyst was proposed.展开更多
Efficiency and recycling of catalysts are important for the lignin hydrogenolysis to obtain phenolic monomers.In this work,a series of highdispersion Ni/AlSBA15 catalysts were prepared by a direct and effective prepar...Efficiency and recycling of catalysts are important for the lignin hydrogenolysis to obtain phenolic monomers.In this work,a series of highdispersion Ni/AlSBA15 catalysts were prepared by a direct and effective preparation method,and then used in the hydrogenolysis of diphenyl ether(DE)and organosolv hydrolyzed lignin(OHL)for phenolic monomers.The universality of asmade catalysts in different solvents and cyclic performance were investigated.Results showed that the addition of ethylene glycol(EG)during the loading process of Ni promoted the dispersion of metal efficiently.High dispersion of Ni species could highly enhance the conversion of DE and the OHL which Ni/AlSBA15(1EG)exhibited the excellent catalytic performance.Decalin was found to be most effective solvent on the conversion of DE(99.16%).84.77%liquefaction ratio and 21.36%monomer yield were achieved,and no obvious char was observed after the depolymerization of OHL in ethanol solvent at 280℃for 4 h over the Ni/AlSBA15(1EG)catalyst.展开更多
In this work the effects of the contents of nickel (5, 7.5, 10 wt%) and copper (0, 1, 2 wt%) and reac- tion temperature (650, 700, 750 ℃) on the catalytic performance of Ni-Cu/Al_2O_3 catalyst in methane dry re...In this work the effects of the contents of nickel (5, 7.5, 10 wt%) and copper (0, 1, 2 wt%) and reac- tion temperature (650, 700, 750 ℃) on the catalytic performance of Ni-Cu/Al_2O_3 catalyst in methane dry reforming were evaluated using Box-Behnken design in order to optimize methane conversion, H_2/CO ratio and the catalyst deactivation. Different catalysts were prepared by co-impregnation method and characterized by XRD, BET, H_2-TPR, FESEM and TG/DTA analyses. The results revealed that copper addi- tion improved the catalyst reducibility. Promoted catalyst with low amounts of Cu gave higher activity and stability with high resistance to coke deposition and agglomeration of active phase especially during the reaction. However catalysts with high amounts of Cu were less active and rather deactivated due to the active sites sintering as well as Ni covering by Cu-enriched phase. The optimal conditions were de- termined by desirability function approach as 10 wt% of Ni, 0.83 wt% of Cu at 750℃. CH_4 conversion of 95.1%, H_2/CO ratio of 1 and deactivation of 1.4% were obtained experimentally under optimum conditions, which were in close agreement with the values oredicted hv the developed model.展开更多
基金The financial support of the Natural Sciences and Engineering Research Council of Canada(NSERC)the CIRCUIT Program(Centre for Innovation and Research on carbon utilization in industrial technologies,NSERC CREATE program)NSERC for the Alexander Graham Bell Canada Graduate Scholarship(BESCD)。
文摘Steam reforming(SR)of fossil methane is already a well-known,documented and established expertise in the industrial sector as it accounts for the vast majority of global hydrogen production.From a sustainable development perspective,hydrogen production by SR of biomass-derived feedstock represents a promising alternative that could help to lower the carbon footprint of the traditional process.In this regard,bio-alcohols such as methanol,ethanol or glycerol are among the attractive candidates that could serve as green hydrogen carriers as they decompose at relatively low temperatures in the presence of water compared to methane,allowing for improved H_(2)yields.However,significant challenges remain regarding the activity and stability of nickel-based catalysts,which are most widely used in alcohol SR processes due to their affordability and ability to break C–C,O–H and C–H bonds,yet are prone to rapid deactivation primarily caused by coke deposition and metal particle sintering.In this state-of-the-art review,a portfolio of strategies to improve the performance of Ni-based catalysts used in alcohol SR processes is unfolded with the intent of pinpointing the critical issues in catalyst development.Close examination of the literature reveals that the efforts tackling these recurring issues can be directed at the active metal,either by tuning Ni dispersion and Ni-support interactions or by targeting synergistic effects in bimetallic systems,while others focus on the support,either by modifying acid-base character,oxygen mobility,or by embedding Ni in specific crystallographic structures.This review provides a very useful tool to orient future work in catalyst development.
基金Financial funds from the Chinese Natural Science Foundation(Project No.20473009)the Beijing Natural Science Foundation(Project No.8062023)+1 种基金the National Basic Research Program of China(Project No.2005CB221405)the National"863"Project of China(No.2006 AA10Z425)are gratefully acknowledged.
文摘A series of Ni/SBA-15 catalysts with Ni contents ranging from 5wt% to 20wt% as well as 10wt%Ni/10wt%CexZr1-xO2/SBA-15 (x=0, 0.5, 1) were prepared. The structures of the catalysts were characterized using XRD, TPR, TEM and BET techniques. The catalytic activities of the catalysts for steam reforming of methane were evaluated in a continuous flow microreactor. The results indicated that both the Ni/SBA-15 and the Ni/CexZr1-xO2/SBA-15 catalysts had good catalytic activities at at- mospheric pressure. The 10wt%Ni/SBA-15 catalyst exhibited excellent stability at 800 ℃ for time on stream of 740 h. After the reaction, carbon deposits were not formed on the surface of the catalyst. There existed a regular hexagonal mesoporous structure in the Ni/SBA-15 and the Ni/CexZr1-xO2/SBA-15 catalysts. The nickel species and the CexZr1-xO2 component were all confined in the SBA-15 mesopores. The CexZr1-xO2 could promote dispersion of the nickel species in the Ni/CexZr1-xO2/SBA-15 catalysts.
基金financially supported by the National Natural Science Foundation of China(22078064)Natural Science Foundation of Fujian Province for Distinguished Young Scholar(2018J06002)。
文摘The hydrogenation of petroleum resin(PR)is an effective process to prepare high value-added hydrogenated PR(HPR).However,the preparation of non-noble metal-based catalysts with high catalytic activity for PR hydrogenation still remains a challenge.Herein,a La promoted Ni-based catalyst is reported through the thermal reduction of quaternary Ni La Mg Al-layered double hydroxides(Ni La Mg Al-LDHs).The incorporation of La is beneficial to the reduction and stability of Ni particles with reduced particle size,and the increased alkalinity effectively mitigates the breakage of molecular chains of PR.As a result,the La promoted Ni-based catalyst exhibits high catalytic activity and excellent stability for PR hydrogenation.A hydrogenation degree of 95.4%and 96.1%can be achieved for HC_(5)PR and HC_(9) PR with less reduced softening point,respectively.Notably,the hydrogenation degree still maintains at 92.7%even after 100 hours’reaction,much better than that without La incorporation or prepared using conventional impregnation method.
基金supported by the National Basic Research Program of China (Project No. 2005CB221405)the National "863" Project of China (No.2006AA10Z425)
文摘A series of Ni/SBA-15 catalysts with 5wt% to 15wt% Ni content as well as a series of 12.5%Ni/Cu/SBA-15 catalysts with 1% to 10% copper content were prepared by the impregnation method. The catalytic performance for partial oxidation of methane was investigated in a continuous flow microreactor under atmospheric pressure. The textural and chemical properties of the catalysts were characterized by XRD, TEM, BET and Hz-TPR techniques. The results indicated that the catalysts modified with Cu promoter showed better performance than those without modification. For the 12.5%Ni/2.5%/Cu/SBA-15 catalyst, at 850 ℃ the conversion of CH4 reached 97.9% and the selectivity of CO and H2 reached 98.0% and 96.0%, respectively. In XRD patterns of the Ni/Cu/SBA-15 catalyst with 7.5 to 10% Cu contents there were CuO characteristic peaks beside NiO characteristic peaks. The mesoporous structure of SBA-15 was retained in all of the catalysts. TPR analysis of the catalysts revealed that a strong interaction between Ni, Cu promoter and SBA-15 support may be existed. This interaction enhanced significantly the redox properties of the catalysts resulting in the higher catalytic activity.
基金supported by the National Natural Science Foundations of China(21965024,22269016,51721002)the Inner Mongolia funding(2020JQ01,21300-5223601)the funding of Inner Mongolia University(10000-21311201/137,213005223601/003,21300-5223707)。
文摘Generating sufficient strains on metal surfaces are highly challenging owing to that most metals can deform plastically to relax the strains on the surfaces.In this work,we developed a facile but highly efficient stacked deposition strategy to in situ activation and reconstruction of NiO/NiOOH on Ni matrix,following with the migration of Fe ions to NiOOH.The Fe sites on the Ni/NiO/NiOOH facilitate the formation of the stable*OH oxygenated intermediates,and the Ni matrix in the catalyst provides the catalyst excellent stability.The oxygen evolution reaction(OER)performance of the stacked NiFe-5 with compressive strain displays the strengthened binding to oxygenated intermediates and superior OER activity,the ultralow overpotentials of 162 versus reversible hydrogen electrode at 10 mA cm^(-2).On the other hand,the Ni-5 without the incorporation of Fe has shown an outstanding hydrogen evolution reaction(HER)activity,affording an overpotential of 47 mV at 10 mA cm^(-2).The NiFe-5‖Ni-5 enables the overall water splitting at a voltage of 1.508 V to achieve 20 mA cm^(-2) with remarkable durability.The stacked deposition strategy improves binding strength of Ni-based catalysts to oxygenated intermediates via generating compressive strain,causing high catalytic activities on OER and HER.
基金the National Basic Research Program ofChina (Project No. 2005CB221405)the National "863" Project ofChina (No. 2006AA10Z425)the Beijing Natural Science Foun-dation (Project No: 8062023)
文摘A series of Ni/SBA-15 catalysts with Ni contents ranging from 5 wt% to 15 wt%, as well as another series of 10%Ni/MgO/SBA-15 catalysts, in which the range of the MgO content was from 1 wt% to 7 wt%, were prepared, and their catalytic performances for the reaction of combined steam and carbon dioxide reforming of methane were investigated in a continuous flow microreactor. The structures of the catalysts were characterized using the XRD, H2-TPR and CO2-TPD techniques. The results indicated that the CO selectivity for this reaction was very close to 100%, and the H2/CO ratio of the product gas could be controlled by changing the H2O/CO2 molar ratio of the feed gas. The simultaneous and plentiful existing of steam and CO2 had a significant influence on the catalytic performance of the 10%Ni/SBA-15 catalyst without modification. After reacting at 850 °C for 120 h over this catalyst, the CH4 conversion dropped from 98% to 85%, and the CO2 conversion decreased from 86% to 53%. However, the 10%Ni/3%MgO/SBA-15 catalyst exhibited a much better catalytic performance, and after reacting for 620 h, the CO2 conversion over this catalyst dropped from 92% to around 77%, while the CH4 conversion was not decreased. Oxidation of the Ni0 species as well as carbon deposition during the reaction were the main reasons for the deactivation of the catalyst without modification. On the other hand, modification by the MgO promoter improved the dispersion of the Ni0 species, and enhanced the CO2 adsorption affinity which in turn depressed the occurring of carbon deposition, and thus retarded the deactivation process.
基金supported by the National Basic Research Program of China(Project No.2005CB221405)the National "863" Project of China (No.2006AA10Z425)the Beijing Natural Science Foundation (Project No: 8062023)
文摘A series of Ni/SBA-15 catalysts with Ni contents from 7.5 wt% to 15 wt% were prepared by impregnation method.The effect of O2 and H2O on the combined reforming of the simulated biogas to syngas was investigated in a continuous flow fixed-bed micro-reactor.The stability of the catalyst was tested at 800 ?C.The results indicated that 10wt%Ni/SBA-15 catalyst exhibited the highest catalytic activities for the combined reforming of the simulated biogas to syngas.Under the reaction conditions of the feed gas molar ratios CH4/CO2/O2/H2O = 2/1/0.6/0.6,GHSV = 24000 ml·gcat^-1·h^-1 and the reaction temperature T = 800 ℃,the conversions of CH4 and CO2 were 92.8% and 76.3%,respectively,and the yields of CO and H2 were 99.0% and 82.0%,respectively.The catalytic activities of the catalyst did not decrease obviously after 100 h reaction time on stream.
文摘Highly active and selective Ni-based catalysts for partial oxidation of methane (POM) to syngas (CO/H,) have been studied and developed. Spectroscopic characterization by XRD, XPS, EPR, etc. demonstrated that under the POM reaction conditions, the Ni-components of the catalysts investigated were reduced and enriched on the surface to form metallic Ni0-phase. A comparative study of the first series of transition-metals showed that only Ni and Co have a high POM activity and selectivity, whereas the others (including Mn, Fe, Cu, etc. ) give mainly complete combustion products, Co, and H2O. The results favor the following viewpoints: the PoM activity is related with the rapidly changeable valence transitionmetal sites, M0/M2+ (e. g. Ni0/Ni2+ ), on the surface of the functioning catalysts;the transition-metal sites in zero-valence state seem to be responsible for the activation and dehydrogenation of methane by homolytic splitting of its C-H bonds on these sites. and the nature of rapidly changeable valence of the active sties is requisite for activation and rapid conversion of dioxygen.
基金support of this work by the project“Development of new innovative low carbon energy technologies to improve excellence in the Region of Western Macedonia”(MIS 5047197)which is implemented under the Action“Reinforcement of the Research and Innovation Infrastructure”funded by the Operational Program“Competitiveness,Entrepreneurship and Innovation”(NSRF 2014-2020)co-financed by Greece and the European Union(European Regional Development Fund)。
文摘In this study,Ni catalysts supported on Pr-doped Ce O_(2) are studied for the CO_(2) methanation reaction and the effect of Pr doping on the physicochemical properties and the catalytic performance is thoroughly evaluated.It is shown,that Pr^(3+)ions can substitute Ce^(4+)ones in the support lattice,thereby introducing a high population of oxygen vacancies,which act as active sites for CO_(2) chemisorption.Pr doping can also act to reduce the crystallite size of metallic Ni,thus promoting the active metal dispersion.Catalytic performance evaluation evidences the promoting effect of low Pr loadings(5 at%and 10 at%)towards a higher catalytic activity and lower CO_(2) activation energy.On the other hand,higher Pr contents negate the positive effects on the catalytic activity by decreasing the oxygen vacancy population,thereby creating a volcano-type trend towards an optimum amount of aliovalent substitution.
基金supported by the National Basic Research Program of China(No.2005CB221405)the National"863"Project of China(No.2006AA10Z425)
文摘A series of Ni/SBA-15 catalysts with Ni contents from 5 wt%–20 wt%and CaO-12.5%Ni/SBA-15 catalysts with CaO contents from 1.4 wt%– 9.8 wt%have been prepared.The structure of the catalysts was characterized using X-ray diffraction(XRD),N2 adsorption-desorption,transmission electron microscopy(TEM)and X-ray photoelectron spectroscopy(XPS).The performance of catalytic steam reforming of the poplar leaves to the hydrogen-rich syngas was tested in a fixed-bed reactor.The results indicate that the 7.0wt%CaO-12.5wt%Ni/SBA-15 catalyst exhibits the best performance for the catalytic steam reforming of poplar leaves to hydrogen-rich syngas.The ratio of H2:CO can reach ca 5:1 in the hydrogen-rich syngas.The yield of H2 can reach 273.30 mL/g(poplar leaves).In the CaO-Ni/SBA-15 catalyst,Ni active component mainly fills the role of catalytic steam reforming of the poplar leaves,and CaO active component mainly plays the role as water-gas shift and CO2 sorbent.
基金supported by JARA-Energy(Seed Fund–JARAENERGY MF 005-17 and the joined project“value chains based on CO_(2)”)the Cluster of Excellence Fuel Science Center(EXC 2186,ID:390919832),which is funded by the Excellence Initiative by the German federal and state governments to promote science and research at German universities+1 种基金supported by the National Key Research and Development Program of China(2019YFA0405602)China Scholarship Council(201806420028)。
文摘Ni-based catalysts are widely investigated non-noble metal-based systems for CO_(2)methanation.However,their industrial application is still limited due to lower activity at low-temperature and catalyst deactivation.Incorporating a second metal such as Ru and Fe is considered as a successful strategy to overcome these challenges through alloy formation or the synergies provided by the interplay of two adjacent metallic sites.Nonetheless,their promotional effect on the CO_(2)methanation mechanism under similar conditions has not been reported yet.In this work,Fe and Ru-promoted Ni/ZrO_(2)catalysts were investigated to evaluate their promotional effect on the mechanism.The Ni/Fe ratio was first optimized and a CO_(2)conversion rate of 37.7 mmolCO_(2)/(molNi+Fes)and 96.3%CH^(4)selectivity was obtained over the Ni_(0.8)Fe_(0.2)/ZrO_(2)catalyst.In comparison with Ni_(0.8)Fe_(0.2)/ZrO_(2),Ni_(0.8)Ru_(0.2)/ZrO_(2)prepared with the same composition showed higher activity and stability in CO_(2)methanation.Characterization results indicate alloys formation and H spillover for Ni_(0.8)Ru_(0.2)/ZrO_(2)to be responsible for promotion.Besides,in situ DRIFTS studies evidenced the occurrence of both CO_(2)dissociative and associative pathways over Ni_(0.8)Ru_(0.2)/ZrO_(2)catalyst,while solely the CO_(2)associative pathway occurred for Ni_(0.8)Fe_(0.2)/ZrO_(2)
基金supported by the National Natural Science Foundation of China (NO. 20976013, 21006057)
文摘CeO2-promoted Ni/Al2O3-ZrO2 (Ni/Al2O3-ZrO2-CeO2) catalysts were prepared by a direct sol-gel process with citric acid as gelling agent. The catalysts used for the methane reforming with CO2 was studied by infrared spectroscopy (IR), thermal gravimetric analysis (TGA), microscopic analysis, X-ray diffraction (XRD) and temperature-programmed reduction (TPR). The catalytic performance for CO2 reforming of methane to synthesis gas was investigated in a continuous-flow micro-reactor under atmospheric pressure. TGA, IR, XRD and microscopic analysis show that the catalysts prepared by the direct sol-gel process consist of Ni particles with a nanostructure of around 5 nm and an amorphous-phase composite oxide support. There exists a chemical interaction between metallic Ni particles and supports, which makes metallic Ni well dispersed, highly active and stable. The addition of CeO2 effectively improves the dispersion and the stability of Ni particles of the prepared catalysts, and enhances the adsorption of CO2 on the surface of catalysts. The catalytic tests for methane reforming with CO2 to synthesis gas show that the Ni/Al2O3-ZrO2-CeO2 catalysts show excellent activity and stability compared with the Ni/Al2O3 catalyst. The excellent catalytic activity and stability of the Ni/Al2O3-ZrO2-CeO2 are attributed to the highly, uniformly and stably dispersed small metallic Ni particles, the high reducibility of the Ni oxides and the interaction between metallic Ni particles and the composite oxide supports.
基金financially supported by the National Natural Science Foundation of China (22006059, 21968015)National Engineering Laboratory for Flue Gas Pollutants Control Technology and Equipment (NEL-KF-201905)+1 种基金Applied Basic Research Program of Yunnan Province, China (202101AU070154, 2019FD034)Analysis and Testing Fund of Kunming University of Science and Technology (2020 T20200006)
文摘The cognition of active sites in the Ni-based catalysts plays a vital role and remains a huge challenge in improving catalytic performance of low temperature CO_(2) dry reforming of methane(LTDRM).In this work,typical catalysts of SiO_(2) and γ-Al_(2)O_(3) supported Ni and Ni-Ce were designed and prepared.Importantly,the difference in the chemical speciations of active sites on the Ni-based catalysts is revealed by advanced characterizations and further estimates respective catalytic performance for LTDRM.Results show that larger[Ni0-]particles mixed with[Ni-O-Sin])species on the Ni/SiO_(2)(R)make CH_(4) excessive decomposition,leading to poor activity and stability.Once the Ce species is doped,however,superior activity(59.0%CH_(4) and 59.8%CO_(2) conversions),stability and high H_(2)/CO ratio(0.96)at 600℃ can be achieved on the Ni-Ce/SiO_(2)(R),in comparison with other catalysts and even reported studies.The improved performance can be ascribed to the formation of integral([Ni0_(n))]-[CeⅢ-□-CeⅢ])species on the Ni-Ce/SiO_(2)(R)catalyst,containing highly dispersed[Ni]particles and rich oxygen vacancies,which can synergistically establish a new stable balance between gasification of carbon species and CO_(2) dissocia-tion.With respect to Ni-Ce/γ-Al_(2)O_(3)(R),the Ni and Ce precursors are easily captured by extra-framework Al_(n)-OH groups and further form stable isolated([Ni0_(n))]-[Ni-O-Al_(n)])and[CeⅢ-O-Al_(n)]species.In such a case,both of them preferentially accelerate CO_(2) adsorption and dissociation,causing more car-bon deposition due to the disproportionation of superfuous CO product.This deep distinguishment of chemical speciations of active sites can guide us to further develop new efficient Ni-based catalysts for LTDRM in the future.
基金financially supported by the National Science Foundation of China (21671132)Shanghai Science and Technology Committee(16dz1207200)the Youth Innovation Promotion Association CAS(2015231)
文摘MnOx-promoted Ni-based catalyst supported by ZnO was developed to selectively hydrogenate glucose into polyols in water at 523 K with a yield of 64.9%. Using glucose, sorbitol, glycerol and LA as the rawmaterials, the roles of nickel, ZnO and MnOx were investigated. The results show that nickel provided a new pathway of glucose to sorbitol and played an important role in the hydrogenation of C3 intermediates to 1,2-propanediol(1,2-PDO). The high yield of 1, 2-PDO was attributed to effective C–C bond cleavage performance of ZnO support promoted by MnOx. ZnO and MnOx contribute to the conversion of glycerol to lactic acid(LA) and LA to 1, 2-PDO, respectively. A concise pathway for hydrogenation of glucose over Ni-based catalyst was proposed.
基金the National Natural Science Foundation of China(No.51676191&5181101221)Local Innovative and Research Teams Project of Guangdong Pearl River Talents Program(No.2017BT01N092)+1 种基金“Transformational Technologies for Clean Energy and Demonstration”,Strategic Priority Research Program of the Chinese Academy of Sciences(No.XDA 21060102)Jiangsu Key Laboratory for Biomass Energy and Material(JSBEM201905).
文摘Efficiency and recycling of catalysts are important for the lignin hydrogenolysis to obtain phenolic monomers.In this work,a series of highdispersion Ni/AlSBA15 catalysts were prepared by a direct and effective preparation method,and then used in the hydrogenolysis of diphenyl ether(DE)and organosolv hydrolyzed lignin(OHL)for phenolic monomers.The universality of asmade catalysts in different solvents and cyclic performance were investigated.Results showed that the addition of ethylene glycol(EG)during the loading process of Ni promoted the dispersion of metal efficiently.High dispersion of Ni species could highly enhance the conversion of DE and the OHL which Ni/AlSBA15(1EG)exhibited the excellent catalytic performance.Decalin was found to be most effective solvent on the conversion of DE(99.16%).84.77%liquefaction ratio and 21.36%monomer yield were achieved,and no obvious char was observed after the depolymerization of OHL in ethanol solvent at 280℃for 4 h over the Ni/AlSBA15(1EG)catalyst.
文摘In this work the effects of the contents of nickel (5, 7.5, 10 wt%) and copper (0, 1, 2 wt%) and reac- tion temperature (650, 700, 750 ℃) on the catalytic performance of Ni-Cu/Al_2O_3 catalyst in methane dry reforming were evaluated using Box-Behnken design in order to optimize methane conversion, H_2/CO ratio and the catalyst deactivation. Different catalysts were prepared by co-impregnation method and characterized by XRD, BET, H_2-TPR, FESEM and TG/DTA analyses. The results revealed that copper addi- tion improved the catalyst reducibility. Promoted catalyst with low amounts of Cu gave higher activity and stability with high resistance to coke deposition and agglomeration of active phase especially during the reaction. However catalysts with high amounts of Cu were less active and rather deactivated due to the active sites sintering as well as Ni covering by Cu-enriched phase. The optimal conditions were de- termined by desirability function approach as 10 wt% of Ni, 0.83 wt% of Cu at 750℃. CH_4 conversion of 95.1%, H_2/CO ratio of 1 and deactivation of 1.4% were obtained experimentally under optimum conditions, which were in close agreement with the values oredicted hv the developed model.