Nickel-based catalysts represent the most commonly used systems for CO methanation.We have successfully prepared a Ni catalyst system supported on two-dimensional plasma-treated vermiculite（2D-PVMT）with a very low N...Nickel-based catalysts represent the most commonly used systems for CO methanation.We have successfully prepared a Ni catalyst system supported on two-dimensional plasma-treated vermiculite（2D-PVMT）with a very low Ni loading（0.5 wt%）.The catalyst precursor was subjected to heat treatment via either conventional heat treatment（CHT）or the plasma irradiation method（PIM）.The as-obtained CHT-Ni/PVMT and PIM-Ni/PVMT catalysts were characterized with scanning electron microscopy（SEM）,energy dispersive X-ray（EDX）,X-ray diffraction（XRD）,X-ray photoelectron spectroscopy（XPS）,inductively coupled plasma-atomic emission spectroscopy（ICP-AES）and high-angle annular dark field scanning transmission electron microscopy（HAADF-STEM）.Additionally,CHT-NiO/PVMT and PIM-NiO/PVMT catalysts were characterized with hydrogen temperature programmed reduction（H2-TPR）.Compared with CHT-Ni/PVMT,PIM-Ni/PVMT exhibited superior catalytic performance.The plasma treated catalyst PIM-Ni/PVMT achieved a CO conversion of93.5%and a turnover frequency（TOF）of 0.8537 s^-1,at a temperature of 450℃,a gas hourly space velocity of 6000 ml·g^-1·h^-1,a synthesis gas flow rate of 65 ml·min^-1,and a pressure of 1.5 MPa.Plasma irradiation may provide a successful strategy for the preparation of catalysts with very low metal loadings which exhibit excellent properties.展开更多
Ni-Al mixed metal oxides have been successfully prepared by high shear mixer(HSM)and coprecipitation(CP)methods for low temperature CO methanation.In this work,Ni-Al(HSM-CP)catalyst presented small Ni crystallite size...Ni-Al mixed metal oxides have been successfully prepared by high shear mixer(HSM)and coprecipitation(CP)methods for low temperature CO methanation.In this work,Ni-Al(HSM-CP)catalyst presented small Ni crystallite size and high surface area,which all contribute to the methanation reaction at low temperature conditions.The obtained Ni-Al(HSM-CP)sample exhibited a mass of defective oxygen,thereby accelerating the dissociation of CO and ultimately increasing the activity of the catalyst.Ni-Al(HSM-CP)catalyst offered the best activity with CO conversion=100%and CH_(4) selectivity=93%at 300℃,and the CH_(4) selectivity can reach 81.8%at 200℃.In situ Fourier transform infrared spectroscopy and density functional theory show that CHO and COH intermediates with lower activation energy barriers are produced during the reaction,and hydrogen-assisted carbon–oxygen bond scission is more favorable.展开更多
In this study,the combustion characteristics and kinetics of cotton straw(CS)particles mixed with polyethylene(PE)film and coal gangue(CG)were investigated.The co-combustion characteristics of CS mixed with PE and CG ...In this study,the combustion characteristics and kinetics of cotton straw(CS)particles mixed with polyethylene(PE)film and coal gangue(CG)were investigated.The co-combustion characteristics of CS mixed with PE and CG at different heating rates were revealed by the thermogravimetric method and differential thermogravimetric method.The ignition temperature,burnout temperature,and maximum weight loss rate were measured,and the comprehensive combustion and flammability indexes were calculated.The results showed that the composite combustion characteristic index and flammability index increased with the increase in heating rate.The addition of PE and CG additives could effectively extend the combustion time.The Coats-Redfern(C-R)reaction model and N-order reaction model were used to evaluate the kinetic parameters of the blends.The results showed that 12.5%PE+12.5%CG particles had the lowest activation energy(Ea=103.73 kJ·mol^(-1))at the volatile combustion stage.The dynamics conform to the third-order dynamics model.In addition,the applicability of C-R model,Flynn-Wall-Ozawa(FWO)model,and Starink model in the calculation of activation energy was explored,and it was found that the FWO model is not suitable for the calculation of activation energy of biomass pellet combustion kinetics.This study provides a new method for the development and utilization of mixed fuel particles of cotton stalk and solid waste and expands the application prospect of biomass.展开更多
The use of non-noble nickel-based catalysts for low temperature CO methanation has been a challenge in recent years.Herein,MgAl layered double oxides sample with high dispersion synthesized by a facile N-(2-Hydroxyeth...The use of non-noble nickel-based catalysts for low temperature CO methanation has been a challenge in recent years.Herein,MgAl layered double oxides sample with high dispersion synthesized by a facile N-(2-Hydroxyethyl)ethylenediaminetriacetic acid assisted wetness impregnation approach,demonstrates much superior catalytic activity and exceptional stability for CO methanation in comparison with the classical Ni/MgAl-LDO catalyst prepared by the ordinary wetness impregnation method.HRTEM results showed that N-(2-Hydroxyethyl)ethylenediaminetriacetic acid played a positive role in the dispersion of Ni,as well as Ni-support interaction.Well-dispersed Ni particles with a size of about 5 nm were formed in the presence of N-(2-Hydroxyethyl)ethylenediaminetriacetic acid.Compared to the Ni/MgAl-LDO prepared by conventional impregnation method,the NH-Ni/MgAl-LDO exhibited superior catalytic performance,especially excellent thermal stability.The NH-Ni30/MgAl-LDO catalyst was found to keep a 70%CO conversion even at 160◦C which demonstrates its good low temperature performance.From the in situ FTIR observations,this good performance at low temperatures may be linked to the delocalization of electrons around CO caused by surface hydroxyl groups.展开更多
基金Supported by the National Natural Science Foundation of China(U1203293,21163015)the Doctor Foundation of Bingtuan(2013BB010)+1 种基金Program of Science and Technology Innovation Team in Bingtuan(2015BD003)Program for Changjiang Scholars,Innovative Research Team in University(IRT_15R46)
文摘Nickel-based catalysts represent the most commonly used systems for CO methanation.We have successfully prepared a Ni catalyst system supported on two-dimensional plasma-treated vermiculite（2D-PVMT）with a very low Ni loading（0.5 wt%）.The catalyst precursor was subjected to heat treatment via either conventional heat treatment（CHT）or the plasma irradiation method（PIM）.The as-obtained CHT-Ni/PVMT and PIM-Ni/PVMT catalysts were characterized with scanning electron microscopy（SEM）,energy dispersive X-ray（EDX）,X-ray diffraction（XRD）,X-ray photoelectron spectroscopy（XPS）,inductively coupled plasma-atomic emission spectroscopy（ICP-AES）and high-angle annular dark field scanning transmission electron microscopy（HAADF-STEM）.Additionally,CHT-NiO/PVMT and PIM-NiO/PVMT catalysts were characterized with hydrogen temperature programmed reduction（H2-TPR）.Compared with CHT-Ni/PVMT,PIM-Ni/PVMT exhibited superior catalytic performance.The plasma treated catalyst PIM-Ni/PVMT achieved a CO conversion of93.5%and a turnover frequency（TOF）of 0.8537 s^-1,at a temperature of 450℃,a gas hourly space velocity of 6000 ml·g^-1·h^-1,a synthesis gas flow rate of 65 ml·min^-1,and a pressure of 1.5 MPa.Plasma irradiation may provide a successful strategy for the preparation of catalysts with very low metal loadings which exhibit excellent properties.
基金This work was supported by National Natural Science Foundation of China(No.22068034)Science and Technology Innovation Talents Program of Bingtuan(No.2019CB025).
文摘Ni-Al mixed metal oxides have been successfully prepared by high shear mixer(HSM)and coprecipitation(CP)methods for low temperature CO methanation.In this work,Ni-Al(HSM-CP)catalyst presented small Ni crystallite size and high surface area,which all contribute to the methanation reaction at low temperature conditions.The obtained Ni-Al(HSM-CP)sample exhibited a mass of defective oxygen,thereby accelerating the dissociation of CO and ultimately increasing the activity of the catalyst.Ni-Al(HSM-CP)catalyst offered the best activity with CO conversion=100%and CH_(4) selectivity=93%at 300℃,and the CH_(4) selectivity can reach 81.8%at 200℃.In situ Fourier transform infrared spectroscopy and density functional theory show that CHO and COH intermediates with lower activation energy barriers are produced during the reaction,and hydrogen-assisted carbon–oxygen bond scission is more favorable.
基金supported by the Scientific and Technological Innovation Leading Talents of Shihezi University(Grant No.CZ002703)Science and Technology Innovation Talents Program of Shihezi University(Grant No.ZG010603)+1 种基金Backbone Technical Innovation Talents of Enterprises(Grant No.2023CB014)Science and Technology Planning Project(Grant No.2023AB032).
文摘In this study,the combustion characteristics and kinetics of cotton straw(CS)particles mixed with polyethylene(PE)film and coal gangue(CG)were investigated.The co-combustion characteristics of CS mixed with PE and CG at different heating rates were revealed by the thermogravimetric method and differential thermogravimetric method.The ignition temperature,burnout temperature,and maximum weight loss rate were measured,and the comprehensive combustion and flammability indexes were calculated.The results showed that the composite combustion characteristic index and flammability index increased with the increase in heating rate.The addition of PE and CG additives could effectively extend the combustion time.The Coats-Redfern(C-R)reaction model and N-order reaction model were used to evaluate the kinetic parameters of the blends.The results showed that 12.5%PE+12.5%CG particles had the lowest activation energy(Ea=103.73 kJ·mol^(-1))at the volatile combustion stage.The dynamics conform to the third-order dynamics model.In addition,the applicability of C-R model,Flynn-Wall-Ozawa(FWO)model,and Starink model in the calculation of activation energy was explored,and it was found that the FWO model is not suitable for the calculation of activation energy of biomass pellet combustion kinetics.This study provides a new method for the development and utilization of mixed fuel particles of cotton stalk and solid waste and expands the application prospect of biomass.
基金National Natural Science Foundation of China(No.22068034)International Science and Technology Cooperation Project of Shihezi University(No.GJHZ201804)+1 种基金International Science and Technology Cooperation Project of Bingtuan(No.2018BC002)Science and Technology Innovation Talents Program of Bingtuan(No.2019CB025).
文摘The use of non-noble nickel-based catalysts for low temperature CO methanation has been a challenge in recent years.Herein,MgAl layered double oxides sample with high dispersion synthesized by a facile N-(2-Hydroxyethyl)ethylenediaminetriacetic acid assisted wetness impregnation approach,demonstrates much superior catalytic activity and exceptional stability for CO methanation in comparison with the classical Ni/MgAl-LDO catalyst prepared by the ordinary wetness impregnation method.HRTEM results showed that N-(2-Hydroxyethyl)ethylenediaminetriacetic acid played a positive role in the dispersion of Ni,as well as Ni-support interaction.Well-dispersed Ni particles with a size of about 5 nm were formed in the presence of N-(2-Hydroxyethyl)ethylenediaminetriacetic acid.Compared to the Ni/MgAl-LDO prepared by conventional impregnation method,the NH-Ni/MgAl-LDO exhibited superior catalytic performance,especially excellent thermal stability.The NH-Ni30/MgAl-LDO catalyst was found to keep a 70%CO conversion even at 160◦C which demonstrates its good low temperature performance.From the in situ FTIR observations,this good performance at low temperatures may be linked to the delocalization of electrons around CO caused by surface hydroxyl groups.
