In order to solve the shortcomings of MoO_(3)/γ-Al_(2)O_(3)catalyst for sulfur-resistant methanation,a segmented plasma fluidized bed reactor was designed,where plasma discharge zone and the fluidization zone were se...In order to solve the shortcomings of MoO_(3)/γ-Al_(2)O_(3)catalyst for sulfur-resistant methanation,a segmented plasma fluidized bed reactor was designed,where plasma discharge zone and the fluidization zone were separated under higher discharge power.At the bed height of 30 mm,the gas velocity of 0.10 m·s^(-1)can provide a better fluidization state.The suitable discharge results can be achieved when the input power is 27 W and the discharge interval is 2.0 mm.With the extension of catalyst plasma treatment time,the conversion of CO decreases,but the selectivity of CH_(4)increases.Combined with N_(2)physical adsorption-desorption,XRD,TEM,Raman,TGA and TPR characterization,it was found that the active components of the catalyst are uniformly dispersed on the γ-Al_(2)O_(3)support.After plasma treatment,tetrahedral Mo species was used as the active center,and the interaction between Mo and the carrier was strengthened.It provides a novel approach for preparing catalyst with dielectric barrier discharge(DBD)fluidized bed reactor.展开更多
Transition metal-carbonate interfaces often act as active sites in heterogeneous catalytic reactions.The interface between transition metal and metal carbonate exhibits a dynamic equilibrium during the CO_(2)hydrogena...Transition metal-carbonate interfaces often act as active sites in heterogeneous catalytic reactions.The interface between transition metal and metal carbonate exhibits a dynamic equilibrium during the CO_(2)hydrogenation reaction,involving surface carbonate hydrogenation and CO_(2)chemisorption.Nonetheless,there have been few reports on engineering the activity of the interface between transition metal and alkaline earth metal carbonate for catalytic CO_(2)conversion.This work demonstrated that the incorporation of CaH_(2)in Ni/CaCO_(3)enhances the CO_(2)methanation activity of the catalysts.The CO_(2)conversion for Ni/CaH_(2)-CaCO_(3)reached 68.5%at 400°C,which was much higher than that of the Ni/CaCO_(3)(31.6%) and Ni/CaH_(2)-CaO (42.4%) catalysts.Furthermore,the Ni/CaH_(2)-CaCO_(3)catalysts remained stable during the stability test for 24 h at 400°C and 8 bar.Our research revealed that CaH_(2)played a crucial role in promoting the activity of the Ni-carbonate interface for CO_(2)methanation.CaH_(2)could modify the electronic structure of Ni and tune the structural properties of CaCO_(3)to generate medium basic sites (OH groups),which are favorable for the activation of H2and CO_(2).In-situ Fourier transform infrared spectroscopy (FTIR) analysis combined with density functional theory calculations demonstrated that CO_(2)activation occurs at the hydroxyl group (OH) on the CaH_(2)-modified Ni-carbonate surface,leading to the formation of CO_(3)H*species.Furthermore,our study has confirmed that CO_(2)methanation over the Ni/CaH_(2)-CaCO_(3)catalysts proceeds via the formate pathway.展开更多
Tuning the metal-oxide interface to achieve optimal catalytic performance represents a classic yet fast-growing area in catalysis research.This work demonstrated that the decoration of CeO_(2) clusters onto Ni particl...Tuning the metal-oxide interface to achieve optimal catalytic performance represents a classic yet fast-growing area in catalysis research.This work demonstrated that the decoration of CeO_(2) clusters onto Ni particles creates electron-enriched Ni sites at the Ni-CeO_(2) interface with highly efficient CO methanation,by kinetics,chemical titration,and a series of in situ/operando spectroscopic characterizations.These electron-enriched Ni atoms facilitate the back-donation of electrons into the orbital of CO and thus reduce the reaction barrier of CH_(4) formation,but do not alter the catalytic steps and their kinetic relevance as well as the evolution of surface intermediates during CO methanation.The amount of electron-enriched Ni atoms increases significantly to a maximum value and then decreases as the content of CeO_(2) increases,leading the formation rates of CH_(4) to increase in a volcano-type relation with CeO_(2) contents in xCeNi/Al_(2)O_(3) catalysts.These insights provide a comprehensive understanding of the nature and the role of the metal-oxide interface and could potentially guide the rational design of highly efficient oxide-supported catalysts for CO methanation.展开更多
Herein,the effect of the Ru:Ni bimetallic composition in dual-function materials(DFMs)for the integrated CO_(2)capture and methanation process(ICCU-Methanation)is systematically evaluated and combined with a thorough ...Herein,the effect of the Ru:Ni bimetallic composition in dual-function materials(DFMs)for the integrated CO_(2)capture and methanation process(ICCU-Methanation)is systematically evaluated and combined with a thorough material characterization,as well as a mechanistic(in-situ diffuse reflectance infrared fourier-transform spectroscopy(in-situ DRIFTS))and computational(computational fluid dynamics(CFD)modelling)investigation,in order to improve the performance of Ni-based DFMs.The bimetallic DFMs are comprised of a main Ni active metallic phase(20 wt%)and are modified with low Ru loadings in the 0.1-1 wt%range(to keep the material cost low),supported on Na_(2)O/Al_(2)O_(3).It is shown that the addition of even a very low Ru loading(0.1-0.2 wt%)can drastically improve the material reducibility,exposing a significantly higher amount of surface-active metallic sites,with Ru being highly dispersed over the support and the Ni phase,while also forming some small Ru particles.This manifests in a significant enhancement in the CH_(4)yield and the CH_(4)production kinetics during ICCU-Methanation(which mainly proceeds via formate intermediates),with 0.2 wt%Ru addition leading to the best results.This bimetallic DFM also shows high stability and a relatively good performance under an oxidizing CO_(2)capture atmosphere.The formation rate of CH_(4)during hydrogenation is then further validated via CFD modelling and the developed model is subsequently applied in the prediction of the effect of other parameters,including the inlet H_(2)concentration,inlet flow rate,dual-fu nction material weight,and reactor internal diameter.展开更多
Nickle-based catalysts are commonly used for CO_(2)methanation.However,there is still potential to improve their catalytic performanc under mild conditions.In this study,we synthesized a series of Ru-Ni-Al catalysts f...Nickle-based catalysts are commonly used for CO_(2)methanation.However,there is still potential to improve their catalytic performanc under mild conditions.In this study,we synthesized a series of Ru-Ni-Al catalysts from Ru-doped NiAl-hydrotalcite using a hydrotherma method.The Ru-Ni-Al catalyst demonstrated much higher activity for CO_(2)methanation than the Ni-Al catalyst that did not have Ru doping Both experimental results and theoretical calculations indicate that the enhanced performance of the Ru-Ni-Al catalyst is related to electroni interactions between nickel(Ni)and ruthenium(Ru).The Ru sites transfer electrons to the Ni sites,increasing the local electron density of Ni which enhances the adsorption and activation of H_(2).Furthermore,the Ru-Ni metal interface sites improve the adsorption and activation of CO_(2)In situ Diffuse Reflectance Infrared Fourier Transform Spectroscopy(DRIFTS)analysis indicates that adjusting the electronic structure of N sites can accelerate the production of intermediates HCOO^(*),while Ru-Ni intermetallic interface sites can directly dissociate CO_(2)into CO^(*).In addition,CO_(2)methanation on the Ru-Ni-Al catalyst follows HCOO^(*)-and CO^(*)-mediated pathways.This study underscores the potential fo enhancing CO_(2)methanation performance by modulating the electronic structure of Ni sites.展开更多
Power-to-methane(P2M)processes,by converting electricity from renewable energy to H2and then into other high value-added and energy-intense chemicals in the presence of active catalysts,have become an effective soluti...Power-to-methane(P2M)processes,by converting electricity from renewable energy to H2and then into other high value-added and energy-intense chemicals in the presence of active catalysts,have become an effective solution for energy storage.However,the fluctuating electricity from intermittent renewable energy leads to a dynamic composition of reactants for downstream methanation,which requires an excellent heterogeneous catalyst to withstand the harsh conditions.Based on these findings,the objective of this review is to classify the fundamentals and status of CO/CO_(2)methanation and identify the pathways in the presence of various catalysts for methane production.In addition,this review sheds insight into the future development and challenges of CO_(2)or CO methanation,including the deactivation mechanisms and catalyst performance under dynamically harsh conditions.Finally,we elaborated on the advantages and development prospects of P2M,and then we summarized the current stage and ongoing industrialization projects of P2M.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
Undoped nickel-based catalysts supported on depleted uranium oxide allow one to carry out CO_(2)methanation process under extremely low reaction temperature under atmospheric pressure and powered by a contactless indu...Undoped nickel-based catalysts supported on depleted uranium oxide allow one to carry out CO_(2)methanation process under extremely low reaction temperature under atmospheric pressure and powered by a contactless induction heating.By adjusting the reaction conditions,the catalyst is able to perform CO_(2)methanation reaction under autothermal process operated inside a non-adiabatic reactor,without any external energy supply.Such autothermal process is possible thanks to the high apparent density of the UO_x which allows one to confine the reaction heat in a small catalyst volume in order to confine the exothermicity of the reaction inside the catalyst and to operate the reaction at equilibrium heat in-heat out.Such autothermal operation mode allows one to significantly reduce the complexity of the process compared to that operated using adiabatic reactor,where complete insulation is required to prevent heat disequilibrium,in order to reduce as much as possible,the heat exchange with the external medium.The catalyst displays an extremely high stability as a function of time on stream as no apparent deactivation.It is expected that such new catalyst with unprecedented catalytic performance could open new era in the field of heterogeneous catalysis where traditional supports show their limitations to operate catalytic processes under severe reaction conditions.展开更多
Promoter-modified Ni-based catalysts were synthesized by an incipient-wetness impregnation method using 3D-mesoporous KIT-6 as a support modified by ethylene glycol, and evaluated for the catalytic production of synth...Promoter-modified Ni-based catalysts were synthesized by an incipient-wetness impregnation method using 3D-mesoporous KIT-6 as a support modified by ethylene glycol, and evaluated for the catalytic production of synthetic natural gas （SNG） from CO methanation. Characterization results suggested that the addition of promoter species could remarkably improve the low-temperature catalytic activity for CO methanation, which was due to a large dispersion of Ni nanoparticles, an enhanced interaction between metal and support as well as a confinement effect of 3D-mesopores. Among all catalysts, Ni-V/KIT-6 possessed the best catalytic performance, which was ascribed to the largest H2 uptake of 177.6 ^mol/g and Ni dispersion of 26.5%, an intimate interaction with the support from the formation of Si-O-V linkage and an enhanced confinement effect of 3D-mesopores to effectively prevent the growth of Ni nanoparticles and carbon filaments. In consequence, Ni-V/KIT-6 displayed excellent catalytic performance as well as high catalytic stability, which can be regarded as a promising candidate for CO methanation.展开更多
Nanostructured titanium dioxides were synthesized via various post-treatments of titanate nanofibers obtained from titanium precursors by hydrothermal reactions. The microstructures of TiO2 and supported Ru/TiO2 catal...Nanostructured titanium dioxides were synthesized via various post-treatments of titanate nanofibers obtained from titanium precursors by hydrothermal reactions. The microstructures of TiO2 and supported Ru/TiO2 catalysts were characterized with X-ray diffraction, transmission electron microscopy, energy-dispersive X-ray analysis, and nitrogen adsorption isotherms. The phase structure, particle size, morphology, and specific surface area were determined. The supported Ru catalysts were applied for the selective methanation of CO in a hydrogen-rich stream. The results indicated that the Ru catalyst supported on rutile and TiO2-B exhibited higher catalytic performance than the counterpart supported on anatase, which suggested the distinct interaction between Ru nanoparticles and TiO2 resulting from different crystalline phases and morphology.展开更多
The novel nickel-based catalysts with a nickel content of 12 wt% were prepared with the zirconia-alumina composite as the supports. The new carriers, ZrO2 improved alumina, were synthesized by three methods, i.e., imp...The novel nickel-based catalysts with a nickel content of 12 wt% were prepared with the zirconia-alumina composite as the supports. The new carriers, ZrO2 improved alumina, were synthesized by three methods, i.e., impregnation-precipitation, co-precipitation, and impregnation method. The catalytic properties of these catalysts were investigated in the methanation of carbon dioxide, and the samples were characterized by X-ray diffraction （XRD）, X-ray photoelectron spectroscope （XPS）, temperature-programmed reduction （TPR） and temperature-programmed desorption （TPD） techniques. The new catalysts showed higher catalytic activity and better stability than Ni/γ-Al2O3. Furthermore, as a support for new nickel catalyst, the ZrO2-Al2O3 composite prepared by the impregnation-precipitation method was more efficient than the other supports in the methanation of carbon dioxide. The highly dispersed zirconium oxide on the surface of γ-Al2O3 inhibited the formation of nickel aluminate-like phase, which was responsible for the better dispersion of Ni species and easier reduction of NiO species, leading to the enhanced catalytic performance of corresponding catalyst.展开更多
The correlation between phase structures and surface acidity of Al2O3 supports calcined at different temperatures and the catalytic performance of Ni/Al2O3 catalysts in the production of synthetic natural gas(SNG) via...The correlation between phase structures and surface acidity of Al2O3 supports calcined at different temperatures and the catalytic performance of Ni/Al2O3 catalysts in the production of synthetic natural gas(SNG) via CO methanation was systematically investigated. A series of 10 wt% NiO/Al2O3 catalysts were prepared by the conventional impregnation method, and the phase structures and surface acidity of Al2O3 supports were adjusted by calcining the commercial γ-Al2O3 at different temperatures(600–1200 C). CO methanation reaction was carried out in the temperature range of 300–600 C at different weight hourly space velocities(WHSV = 30000 and 120000 mL·g-1h-1) and pressures(0.1 and 3.0 MPa). It was found that high calcination temperature not only led to the growth in Ni particle size, but also weakened the interaction between Ni nanoparticles and Al2O3 supports due to the rapid decrease of the specific surface area and acidity of Al2O3 supports. Interestingly, Ni catalysts supported on Al2O3 calcined at 1200 C(Ni/Al2O3-1200) exhibited the best catalytic activity for CO methanation under different reaction conditions. Lifetime reaction tests also indicated that Ni/Al2O3-1200 was the most active and stable catalyst compared with the other three catalysts, whose supports were calcined at lower temperatures(600, 800 and 1000 C). These findings would therefore be helpful to develop Ni/Al2O3 methanation catalyst for SNG production.展开更多
Coral reef-like Ni/Al2O3 catalysts were prepared by co-precipitation of nickel acetate and aluminium nitrate with sodium carbonate aqueous solution in the medium of ethylene glycolye.Methanation of syngas was carried ...Coral reef-like Ni/Al2O3 catalysts were prepared by co-precipitation of nickel acetate and aluminium nitrate with sodium carbonate aqueous solution in the medium of ethylene glycolye.Methanation of syngas was carried out over coral reef-like Ni/Al2O3 catalysts in a continuous flow type fixed-bed reactor.The structure and properties of the fresh and used catalysts were studied by SEM,N2 adsorption-desorption,XRD,H2-TPR,O2-TPO,TG and ICP-AES techniques.The results showed that the coral reef-like Ni/Al2O3 catalysts exhibited better activity than the conventional Ni/Al2O3-H2O catalysts.The activities of coral reef-like catalysts were in the order of Ni/Al2O3-673Ni/Al2O3-573Ni/Al2O3- 473Ni/Al2O3-773.Ni/Al2O3-673-EG catalyst showed not only good activity and improved stability but also superior resistance to carbon deposition,sintering,and Ni loss.Under the reaction conditions of CO/H2（molar ratio）=1：3,593 K,atmospheric pressure and a GHSV of 2500 h-1,CH4 selectivity was 84.7%,and the CO conversion reached 98.2%.展开更多
Ni/ZrO2 catalysts were prepared by the incipient-wetness impregnation method and were investigated in activity and selectivity for the selective catalytic methanation of CO in hydrogen-rich gases with more than 20 vol...Ni/ZrO2 catalysts were prepared by the incipient-wetness impregnation method and were investigated in activity and selectivity for the selective catalytic methanation of CO in hydrogen-rich gases with more than 20 vol% CO2. The result showed that Ni loadings significantly influenced the performance of Ni/ZrO2 catalyst. The 1.6 wt% Ni loading catalyst exhibited the highest catalytic activity among all the catalysts in the selective methanation of CO in hydrogen-rich gas. The outlet concentration of CO was less than 20 ppm with the hydrogen consumption below 7%, at a gas-hourly-space velocity as high as 10000 h-1 and a temperature range of 260 °C to 280 °C. The X-ray diffraction （XRD） and temperature programmed reduction （TPR） measurements showed that NiO was dispersed thoroughly on the surface of ZrO2 support if Ni loading was under 1.6 wt%. When Ni loading was increased to 3 wt% or above, the free bulk NiO species began to assemble, which was not favorable to increase the selectivity of the catalyst.展开更多
CO methanation on Ni/CeO2 has recently received increasing attention.However,the low-temperature activity and carbon resistance of Ni/CeO2 still need to be improved.In this study,plasma decomposition of nickel nitrate...CO methanation on Ni/CeO2 has recently received increasing attention.However,the low-temperature activity and carbon resistance of Ni/CeO2 still need to be improved.In this study,plasma decomposition of nickel nitrate was performed at ca.150℃ and atmospheric pressure.This was followed by hydrogen reduction at 500 ℃ in the absence of plasma,and a highly dispersed Ni/CeO2 catalyst was obtained with improved CO adsorption and enhanced metal-support interaction.The plasma-decomposed catalyst showed significantly improved low-temperature activity with high methane selectivity(up to 100%)and enhanced carbon resistance for CO methanation.For example,at 250 ℃,the plasma-decomposed catalyst showed a CO conversion of 96.8% with high methane selectivity(almost 100%),whereas the CO conversion was only 14.7% for a thermally decomposed catalyst.展开更多
The Ni-CeO2/Al2O3 catalysts with a nickel content of 15 wt% prepared via impregnating boehmite were found to be highly active and stable for methanation of carbon dioxide with hydrogen at a H2/CO2 molar ratio of 4. Th...The Ni-CeO2/Al2O3 catalysts with a nickel content of 15 wt% prepared via impregnating boehmite were found to be highly active and stable for methanation of carbon dioxide with hydrogen at a H2/CO2 molar ratio of 4. The effects of CeO2 content and reaction temperature on the performance of the Ni-CeO2/Al2O3 catalysts were studied in detail. The results showed that the catalytic performance was strongly dependent on the CeO2 content in Ni-CeO2/Al2O3 catalysts and that the catalysts with 2 wt% CeO2 had the highest catalytic activity among the tested ones at 350 ℃. The XRD and H2-TPR characterizations revealed that the addition of CeO2 decreased the reduction temperature by altering the interaction between Ni and Al2O3, and improved the reducibility of the catalyst. Preliminary stability test of 120 h on stream over the Ni-2CeO2/Al2O3 catalyst at 350 ℃ revealed that the catalyst was much better than the unpromoted one.展开更多
In this study, different methods were used to prepare MoO3/ZrO2 catalysts for sulfur resistant methanation reaction. It was found that MoO3/ZrO2 catalyst prepared by one-step co-precipitation method achieved high meth...In this study, different methods were used to prepare MoO3/ZrO2 catalysts for sulfur resistant methanation reaction. It was found that MoO3/ZrO2 catalyst prepared by one-step co-precipitation method achieved high methanation performance. CO conversion could reach up to 90% on 25 wt% MoO3/ZrO2 catalyst, much higher than that on the conventional 25 wt% MoO3/Al2O3 catalyst. The Mo-based catalysts were characterized by XRF, XRD, Raman, BET, TEM and H2-TPR etc. It was found that MoO3 particles were highly dispersed on ZrO2 support for 25 wt% MoO3/ZrO2 catalyst prepared at 65-85℃ because of its relatively larger pore size, which contributed to a high CO conversion. Meanwhile, when MoO3 loading exceeded the monolayer coverage, the formed crystalline MoO3 and ZrM020g might block the micropores of the catalyst and make the methanation activity declined. These results are useful for preparing highly efficient catalyst for CO methanation process.展开更多
Amorphous Ni-Ru-B/ZrO2 catalyst was prepared by the means of chemical reduction, and selective CO methanation as a strategy for CO removal in fuel processing applications was investigated over the amorphous Ni-Ru-B/Zr...Amorphous Ni-Ru-B/ZrO2 catalyst was prepared by the means of chemical reduction, and selective CO methanation as a strategy for CO removal in fuel processing applications was investigated over the amorphous Ni-Ru-B/ZrO2 catalyst. The result showed that, at the temperature of 210-230 ℃, the catalyst was shown to be capable of reducing CO in a hydrogen-rich reformate to less than 10 ppm, while keeping the CO2 conversion below 1.55% and the hydrogen consumption below 6.50%. ？2009 Xin Fa Dong. Published by Elsevier B.V. on behalf of Chinese Chemical Society. All rights reserved.展开更多
The effects of composite supports of CeO2-Al2O3, MgO-Al2O3, TiO2-Al2O3 or ZrO2-Al2O3 on the methanation activity of supported Co-Mo-based sulphur-resistant catalysts were investigated. The catalysts were further chara...The effects of composite supports of CeO2-Al2O3, MgO-Al2O3, TiO2-Al2O3 or ZrO2-Al2O3 on the methanation activity of supported Co-Mo-based sulphur-resistant catalysts were investigated. The catalysts were further characterized by nitrogen adsorption measurement, X-ray diffraction and X-ray photoelectron spectroscopy. The catalyst of 5%CoO-15%MoO3 supported on CeO2-Al2O3, MgO-Al2O3, TiO2-Al2O3 or ZrO2-Al2O3 composite oxides, respectively, showed different catalytic performances of syngas methanation in the presence of hydrogen sulphide as compared with that of the 5%CoO-15%MoO3/Al2O3 catalyst. The Co-Mo/CeO2-Al2O3 catalyst shows the highest methanation activity among the tested catalysts. The enhanced methanation activity may be attributed to the improvement of the dispersion of active metal species and the inhibition of the formation of S6＋.展开更多
Ni/Al2O3 catalysts with different amounts of manganese ranging from 1 to 3 wt% as promoter were prepared by co-impregnation method. The catalysts were characterized by N2 physisorption, XRD, TPR, SEM and TEM. Their ca...Ni/Al2O3 catalysts with different amounts of manganese ranging from 1 to 3 wt% as promoter were prepared by co-impregnation method. The catalysts were characterized by N2 physisorption, XRD, TPR, SEM and TEM. Their catalytic activity towards syngas methanation reaction was also investigated using a fixed-bed integral reactor. It was demonstrated that the addition of manganese to Ni/Al2O3 catalysts can increase the catalyst surface area and average pore volume, but decrease NiO crystallite size, leading to higher activity and stability. The effects of reaction temperature, pressure and weight hourly space velocity （WHSV） on carbon oxides conversion and CH4 formation rate were also studied. High carbon oxides conversion, CH4 selectivity and formation rate were achieved at the reaction temperature range of 280 300℃.展开更多
基金supported by the National Natural Science Foundation of China(22178255).
文摘In order to solve the shortcomings of MoO_(3)/γ-Al_(2)O_(3)catalyst for sulfur-resistant methanation,a segmented plasma fluidized bed reactor was designed,where plasma discharge zone and the fluidization zone were separated under higher discharge power.At the bed height of 30 mm,the gas velocity of 0.10 m·s^(-1)can provide a better fluidization state.The suitable discharge results can be achieved when the input power is 27 W and the discharge interval is 2.0 mm.With the extension of catalyst plasma treatment time,the conversion of CO decreases,but the selectivity of CH_(4)increases.Combined with N_(2)physical adsorption-desorption,XRD,TEM,Raman,TGA and TPR characterization,it was found that the active components of the catalyst are uniformly dispersed on the γ-Al_(2)O_(3)support.After plasma treatment,tetrahedral Mo species was used as the active center,and the interaction between Mo and the carrier was strengthened.It provides a novel approach for preparing catalyst with dielectric barrier discharge(DBD)fluidized bed reactor.
基金National Natural Science Foundation of China (Nos. 22371244 and 21573192)Postgraduate Research&Practice Innovation Program of Jiangsu Province(KYCX22_3463)。
文摘Transition metal-carbonate interfaces often act as active sites in heterogeneous catalytic reactions.The interface between transition metal and metal carbonate exhibits a dynamic equilibrium during the CO_(2)hydrogenation reaction,involving surface carbonate hydrogenation and CO_(2)chemisorption.Nonetheless,there have been few reports on engineering the activity of the interface between transition metal and alkaline earth metal carbonate for catalytic CO_(2)conversion.This work demonstrated that the incorporation of CaH_(2)in Ni/CaCO_(3)enhances the CO_(2)methanation activity of the catalysts.The CO_(2)conversion for Ni/CaH_(2)-CaCO_(3)reached 68.5%at 400°C,which was much higher than that of the Ni/CaCO_(3)(31.6%) and Ni/CaH_(2)-CaO (42.4%) catalysts.Furthermore,the Ni/CaH_(2)-CaCO_(3)catalysts remained stable during the stability test for 24 h at 400°C and 8 bar.Our research revealed that CaH_(2)played a crucial role in promoting the activity of the Ni-carbonate interface for CO_(2)methanation.CaH_(2)could modify the electronic structure of Ni and tune the structural properties of CaCO_(3)to generate medium basic sites (OH groups),which are favorable for the activation of H2and CO_(2).In-situ Fourier transform infrared spectroscopy (FTIR) analysis combined with density functional theory calculations demonstrated that CO_(2)activation occurs at the hydroxyl group (OH) on the CaH_(2)-modified Ni-carbonate surface,leading to the formation of CO_(3)H*species.Furthermore,our study has confirmed that CO_(2)methanation over the Ni/CaH_(2)-CaCO_(3)catalysts proceeds via the formate pathway.
文摘Tuning the metal-oxide interface to achieve optimal catalytic performance represents a classic yet fast-growing area in catalysis research.This work demonstrated that the decoration of CeO_(2) clusters onto Ni particles creates electron-enriched Ni sites at the Ni-CeO_(2) interface with highly efficient CO methanation,by kinetics,chemical titration,and a series of in situ/operando spectroscopic characterizations.These electron-enriched Ni atoms facilitate the back-donation of electrons into the orbital of CO and thus reduce the reaction barrier of CH_(4) formation,but do not alter the catalytic steps and their kinetic relevance as well as the evolution of surface intermediates during CO methanation.The amount of electron-enriched Ni atoms increases significantly to a maximum value and then decreases as the content of CeO_(2) increases,leading the formation rates of CH_(4) to increase in a volcano-type relation with CeO_(2) contents in xCeNi/Al_(2)O_(3) catalysts.These insights provide a comprehensive understanding of the nature and the role of the metal-oxide interface and could potentially guide the rational design of highly efficient oxide-supported catalysts for CO methanation.
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)+4 种基金the Hellenic Foundation for Research and Innovation(HFRI)for supporting this research work under the 3~(rd)Call for HFRI PhD Fellowships(Fellowship Number:6033)the support of ELECMI-LMA nodeNanbiosis ICTSsfunded by the Swiss National Science Foundation(Grant:206021_189629)the Research Council of Norway(Grant:296087)。
文摘Herein,the effect of the Ru:Ni bimetallic composition in dual-function materials(DFMs)for the integrated CO_(2)capture and methanation process(ICCU-Methanation)is systematically evaluated and combined with a thorough material characterization,as well as a mechanistic(in-situ diffuse reflectance infrared fourier-transform spectroscopy(in-situ DRIFTS))and computational(computational fluid dynamics(CFD)modelling)investigation,in order to improve the performance of Ni-based DFMs.The bimetallic DFMs are comprised of a main Ni active metallic phase(20 wt%)and are modified with low Ru loadings in the 0.1-1 wt%range(to keep the material cost low),supported on Na_(2)O/Al_(2)O_(3).It is shown that the addition of even a very low Ru loading(0.1-0.2 wt%)can drastically improve the material reducibility,exposing a significantly higher amount of surface-active metallic sites,with Ru being highly dispersed over the support and the Ni phase,while also forming some small Ru particles.This manifests in a significant enhancement in the CH_(4)yield and the CH_(4)production kinetics during ICCU-Methanation(which mainly proceeds via formate intermediates),with 0.2 wt%Ru addition leading to the best results.This bimetallic DFM also shows high stability and a relatively good performance under an oxidizing CO_(2)capture atmosphere.The formation rate of CH_(4)during hydrogenation is then further validated via CFD modelling and the developed model is subsequently applied in the prediction of the effect of other parameters,including the inlet H_(2)concentration,inlet flow rate,dual-fu nction material weight,and reactor internal diameter.
基金support from the National Natural Science Foundation of China(22278006)Open Project Fund from Guangdong Provincial Key Laboratory of Materials and Technology for Energy Conversion,Guangdong Technion-Israel Institute of Technology(MATEC2024KF009)Open Research Fund of State Key Laboratory of Mesoscience and Engineering(MESO-23-D13)。
文摘Nickle-based catalysts are commonly used for CO_(2)methanation.However,there is still potential to improve their catalytic performanc under mild conditions.In this study,we synthesized a series of Ru-Ni-Al catalysts from Ru-doped NiAl-hydrotalcite using a hydrotherma method.The Ru-Ni-Al catalyst demonstrated much higher activity for CO_(2)methanation than the Ni-Al catalyst that did not have Ru doping Both experimental results and theoretical calculations indicate that the enhanced performance of the Ru-Ni-Al catalyst is related to electroni interactions between nickel(Ni)and ruthenium(Ru).The Ru sites transfer electrons to the Ni sites,increasing the local electron density of Ni which enhances the adsorption and activation of H_(2).Furthermore,the Ru-Ni metal interface sites improve the adsorption and activation of CO_(2)In situ Diffuse Reflectance Infrared Fourier Transform Spectroscopy(DRIFTS)analysis indicates that adjusting the electronic structure of N sites can accelerate the production of intermediates HCOO^(*),while Ru-Ni intermetallic interface sites can directly dissociate CO_(2)into CO^(*).In addition,CO_(2)methanation on the Ru-Ni-Al catalyst follows HCOO^(*)-and CO^(*)-mediated pathways.This study underscores the potential fo enhancing CO_(2)methanation performance by modulating the electronic structure of Ni sites.
基金funded by the National Key Research and Development Program of China(2019YFA0405602)the Hefei Science Center,CAS(2020HSC-KPRD001,2021HSC-UE005)the DNL Cooperation Fund,CAS(DNL202005)。
文摘Power-to-methane(P2M)processes,by converting electricity from renewable energy to H2and then into other high value-added and energy-intense chemicals in the presence of active catalysts,have become an effective solution for energy storage.However,the fluctuating electricity from intermittent renewable energy leads to a dynamic composition of reactants for downstream methanation,which requires an excellent heterogeneous catalyst to withstand the harsh conditions.Based on these findings,the objective of this review is to classify the fundamentals and status of CO/CO_(2)methanation and identify the pathways in the presence of various catalysts for methane production.In addition,this review sheds insight into the future development and challenges of CO_(2)or CO methanation,including the deactivation mechanisms and catalyst performance under dynamically harsh conditions.Finally,we elaborated on the advantages and development prospects of P2M,and then we summarized the current stage and ongoing industrialization projects of P2M.
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ORANO Chimie-Enrichissement Co.for the financial support of this project。
文摘Undoped nickel-based catalysts supported on depleted uranium oxide allow one to carry out CO_(2)methanation process under extremely low reaction temperature under atmospheric pressure and powered by a contactless induction heating.By adjusting the reaction conditions,the catalyst is able to perform CO_(2)methanation reaction under autothermal process operated inside a non-adiabatic reactor,without any external energy supply.Such autothermal process is possible thanks to the high apparent density of the UO_x which allows one to confine the reaction heat in a small catalyst volume in order to confine the exothermicity of the reaction inside the catalyst and to operate the reaction at equilibrium heat in-heat out.Such autothermal operation mode allows one to significantly reduce the complexity of the process compared to that operated using adiabatic reactor,where complete insulation is required to prevent heat disequilibrium,in order to reduce as much as possible,the heat exchange with the external medium.The catalyst displays an extremely high stability as a function of time on stream as no apparent deactivation.It is expected that such new catalyst with unprecedented catalytic performance could open new era in the field of heterogeneous catalysis where traditional supports show their limitations to operate catalytic processes under severe reaction conditions.
基金supported by the Fundamental Research Funds for the Central Universities(2015XKMS061)~~
文摘Promoter-modified Ni-based catalysts were synthesized by an incipient-wetness impregnation method using 3D-mesoporous KIT-6 as a support modified by ethylene glycol, and evaluated for the catalytic production of synthetic natural gas （SNG） from CO methanation. Characterization results suggested that the addition of promoter species could remarkably improve the low-temperature catalytic activity for CO methanation, which was due to a large dispersion of Ni nanoparticles, an enhanced interaction between metal and support as well as a confinement effect of 3D-mesopores. Among all catalysts, Ni-V/KIT-6 possessed the best catalytic performance, which was ascribed to the largest H2 uptake of 177.6 ^mol/g and Ni dispersion of 26.5%, an intimate interaction with the support from the formation of Si-O-V linkage and an enhanced confinement effect of 3D-mesopores to effectively prevent the growth of Ni nanoparticles and carbon filaments. In consequence, Ni-V/KIT-6 displayed excellent catalytic performance as well as high catalytic stability, which can be regarded as a promising candidate for CO methanation.
基金V. ACKNOWLEDGMENTS This work was supported by the National Natural Science Foundation of China （No.20703042）, the National Basic Research Program of China （No.2010 CB923300）, USTC-NSRL Association Funding （No.KY 2060030009）, and Fundamental Research Funds for the Central Universities （No.WK2060030010）.
文摘Nanostructured titanium dioxides were synthesized via various post-treatments of titanate nanofibers obtained from titanium precursors by hydrothermal reactions. The microstructures of TiO2 and supported Ru/TiO2 catalysts were characterized with X-ray diffraction, transmission electron microscopy, energy-dispersive X-ray analysis, and nitrogen adsorption isotherms. The phase structure, particle size, morphology, and specific surface area were determined. The supported Ru catalysts were applied for the selective methanation of CO in a hydrogen-rich stream. The results indicated that the Ru catalyst supported on rutile and TiO2-B exhibited higher catalytic performance than the counterpart supported on anatase, which suggested the distinct interaction between Ru nanoparticles and TiO2 resulting from different crystalline phases and morphology.
基金supported by the Southwest Research & Design Institute of Chemical Industy (SKLIV GR-22010-01)the National Basic Research Program of China (973 Program, 2011CB201202) of Ministry of Science and Technology
文摘The novel nickel-based catalysts with a nickel content of 12 wt% were prepared with the zirconia-alumina composite as the supports. The new carriers, ZrO2 improved alumina, were synthesized by three methods, i.e., impregnation-precipitation, co-precipitation, and impregnation method. The catalytic properties of these catalysts were investigated in the methanation of carbon dioxide, and the samples were characterized by X-ray diffraction （XRD）, X-ray photoelectron spectroscope （XPS）, temperature-programmed reduction （TPR） and temperature-programmed desorption （TPD） techniques. The new catalysts showed higher catalytic activity and better stability than Ni/γ-Al2O3. Furthermore, as a support for new nickel catalyst, the ZrO2-Al2O3 composite prepared by the impregnation-precipitation method was more efficient than the other supports in the methanation of carbon dioxide. The highly dispersed zirconium oxide on the surface of γ-Al2O3 inhibited the formation of nickel aluminate-like phase, which was responsible for the better dispersion of Ni species and easier reduction of NiO species, leading to the enhanced catalytic performance of corresponding catalyst.
基金supported by the Hundred Talents Program of the Chinese Academy of Sciences (CAS),State Key Laboratory of Multiphase Complex Systems of China (No.MPCS-2009-C-01)the National Key Technology R&D Program of China (No.2010BAC66B01)the Knowledge Innovation Program of the CAS (No.KGCX2-YW-396)
文摘The correlation between phase structures and surface acidity of Al2O3 supports calcined at different temperatures and the catalytic performance of Ni/Al2O3 catalysts in the production of synthetic natural gas(SNG) via CO methanation was systematically investigated. A series of 10 wt% NiO/Al2O3 catalysts were prepared by the conventional impregnation method, and the phase structures and surface acidity of Al2O3 supports were adjusted by calcining the commercial γ-Al2O3 at different temperatures(600–1200 C). CO methanation reaction was carried out in the temperature range of 300–600 C at different weight hourly space velocities(WHSV = 30000 and 120000 mL·g-1h-1) and pressures(0.1 and 3.0 MPa). It was found that high calcination temperature not only led to the growth in Ni particle size, but also weakened the interaction between Ni nanoparticles and Al2O3 supports due to the rapid decrease of the specific surface area and acidity of Al2O3 supports. Interestingly, Ni catalysts supported on Al2O3 calcined at 1200 C(Ni/Al2O3-1200) exhibited the best catalytic activity for CO methanation under different reaction conditions. Lifetime reaction tests also indicated that Ni/Al2O3-1200 was the most active and stable catalyst compared with the other three catalysts, whose supports were calcined at lower temperatures(600, 800 and 1000 C). These findings would therefore be helpful to develop Ni/Al2O3 methanation catalyst for SNG production.
基金financially supported by Independent Research Subject from Ministry of Science and Technology of China(No.2008BWZ005)
文摘Coral reef-like Ni/Al2O3 catalysts were prepared by co-precipitation of nickel acetate and aluminium nitrate with sodium carbonate aqueous solution in the medium of ethylene glycolye.Methanation of syngas was carried out over coral reef-like Ni/Al2O3 catalysts in a continuous flow type fixed-bed reactor.The structure and properties of the fresh and used catalysts were studied by SEM,N2 adsorption-desorption,XRD,H2-TPR,O2-TPO,TG and ICP-AES techniques.The results showed that the coral reef-like Ni/Al2O3 catalysts exhibited better activity than the conventional Ni/Al2O3-H2O catalysts.The activities of coral reef-like catalysts were in the order of Ni/Al2O3-673Ni/Al2O3-573Ni/Al2O3- 473Ni/Al2O3-773.Ni/Al2O3-673-EG catalyst showed not only good activity and improved stability but also superior resistance to carbon deposition,sintering,and Ni loss.Under the reaction conditions of CO/H2（molar ratio）=1：3,593 K,atmospheric pressure and a GHSV of 2500 h-1,CH4 selectivity was 84.7%,and the CO conversion reached 98.2%.
基金the National Natural Science Foundation of China (20576023)the Guangdong Province Natural Science Foundation (06025660)
文摘Ni/ZrO2 catalysts were prepared by the incipient-wetness impregnation method and were investigated in activity and selectivity for the selective catalytic methanation of CO in hydrogen-rich gases with more than 20 vol% CO2. The result showed that Ni loadings significantly influenced the performance of Ni/ZrO2 catalyst. The 1.6 wt% Ni loading catalyst exhibited the highest catalytic activity among all the catalysts in the selective methanation of CO in hydrogen-rich gas. The outlet concentration of CO was less than 20 ppm with the hydrogen consumption below 7%, at a gas-hourly-space velocity as high as 10000 h-1 and a temperature range of 260 °C to 280 °C. The X-ray diffraction （XRD） and temperature programmed reduction （TPR） measurements showed that NiO was dispersed thoroughly on the surface of ZrO2 support if Ni loading was under 1.6 wt%. When Ni loading was increased to 3 wt% or above, the free bulk NiO species began to assemble, which was not favorable to increase the selectivity of the catalyst.
基金This work was supported by the National Natural Science Foundation of China(21476157,21536008 and 21621004)the National Key R&D Program of China(2016YFB0600902)~~
文摘CO methanation on Ni/CeO2 has recently received increasing attention.However,the low-temperature activity and carbon resistance of Ni/CeO2 still need to be improved.In this study,plasma decomposition of nickel nitrate was performed at ca.150℃ and atmospheric pressure.This was followed by hydrogen reduction at 500 ℃ in the absence of plasma,and a highly dispersed Ni/CeO2 catalyst was obtained with improved CO adsorption and enhanced metal-support interaction.The plasma-decomposed catalyst showed significantly improved low-temperature activity with high methane selectivity(up to 100%)and enhanced carbon resistance for CO methanation.For example,at 250 ℃,the plasma-decomposed catalyst showed a CO conversion of 96.8% with high methane selectivity(almost 100%),whereas the CO conversion was only 14.7% for a thermally decomposed catalyst.
基金supported by the National High Technology Research and Development Program of China(Grant No.2006AA11A189)Science and Technology Commission of Shanghai Municipality(Grant No.07DZ12036,and08DZ12064)Shanghai Pujiang Program(Grant No.08PJ1405900)
文摘The Ni-CeO2/Al2O3 catalysts with a nickel content of 15 wt% prepared via impregnating boehmite were found to be highly active and stable for methanation of carbon dioxide with hydrogen at a H2/CO2 molar ratio of 4. The effects of CeO2 content and reaction temperature on the performance of the Ni-CeO2/Al2O3 catalysts were studied in detail. The results showed that the catalytic performance was strongly dependent on the CeO2 content in Ni-CeO2/Al2O3 catalysts and that the catalysts with 2 wt% CeO2 had the highest catalytic activity among the tested ones at 350 ℃. The XRD and H2-TPR characterizations revealed that the addition of CeO2 decreased the reduction temperature by altering the interaction between Ni and Al2O3, and improved the reducibility of the catalyst. Preliminary stability test of 120 h on stream over the Ni-2CeO2/Al2O3 catalyst at 350 ℃ revealed that the catalyst was much better than the unpromoted one.
基金supported by the Tianjin Municipal Science and Technology Commission(14JCZDJC37500)
文摘In this study, different methods were used to prepare MoO3/ZrO2 catalysts for sulfur resistant methanation reaction. It was found that MoO3/ZrO2 catalyst prepared by one-step co-precipitation method achieved high methanation performance. CO conversion could reach up to 90% on 25 wt% MoO3/ZrO2 catalyst, much higher than that on the conventional 25 wt% MoO3/Al2O3 catalyst. The Mo-based catalysts were characterized by XRF, XRD, Raman, BET, TEM and H2-TPR etc. It was found that MoO3 particles were highly dispersed on ZrO2 support for 25 wt% MoO3/ZrO2 catalyst prepared at 65-85℃ because of its relatively larger pore size, which contributed to a high CO conversion. Meanwhile, when MoO3 loading exceeded the monolayer coverage, the formed crystalline MoO3 and ZrM020g might block the micropores of the catalyst and make the methanation activity declined. These results are useful for preparing highly efficient catalyst for CO methanation process.
基金supported by the National Natural Science Foundation of China(No.20576023)the Guangdong Province Natural Science Foundation(No.06025660).
文摘Amorphous Ni-Ru-B/ZrO2 catalyst was prepared by the means of chemical reduction, and selective CO methanation as a strategy for CO removal in fuel processing applications was investigated over the amorphous Ni-Ru-B/ZrO2 catalyst. The result showed that, at the temperature of 210-230 ℃, the catalyst was shown to be capable of reducing CO in a hydrogen-rich reformate to less than 10 ppm, while keeping the CO2 conversion below 1.55% and the hydrogen consumption below 6.50%. ？2009 Xin Fa Dong. Published by Elsevier B.V. on behalf of Chinese Chemical Society. All rights reserved.
文摘The effects of composite supports of CeO2-Al2O3, MgO-Al2O3, TiO2-Al2O3 or ZrO2-Al2O3 on the methanation activity of supported Co-Mo-based sulphur-resistant catalysts were investigated. The catalysts were further characterized by nitrogen adsorption measurement, X-ray diffraction and X-ray photoelectron spectroscopy. The catalyst of 5%CoO-15%MoO3 supported on CeO2-Al2O3, MgO-Al2O3, TiO2-Al2O3 or ZrO2-Al2O3 composite oxides, respectively, showed different catalytic performances of syngas methanation in the presence of hydrogen sulphide as compared with that of the 5%CoO-15%MoO3/Al2O3 catalyst. The Co-Mo/CeO2-Al2O3 catalyst shows the highest methanation activity among the tested catalysts. The enhanced methanation activity may be attributed to the improvement of the dispersion of active metal species and the inhibition of the formation of S6＋.
基金supported by the National Science and Technology Supporting Plan (No. 2006BAE02B02)
文摘Ni/Al2O3 catalysts with different amounts of manganese ranging from 1 to 3 wt% as promoter were prepared by co-impregnation method. The catalysts were characterized by N2 physisorption, XRD, TPR, SEM and TEM. Their catalytic activity towards syngas methanation reaction was also investigated using a fixed-bed integral reactor. It was demonstrated that the addition of manganese to Ni/Al2O3 catalysts can increase the catalyst surface area and average pore volume, but decrease NiO crystallite size, leading to higher activity and stability. The effects of reaction temperature, pressure and weight hourly space velocity （WHSV） on carbon oxides conversion and CH4 formation rate were also studied. High carbon oxides conversion, CH4 selectivity and formation rate were achieved at the reaction temperature range of 280 300℃.
