EDTA Assisted Synthesis Of Nickel Nanoparticles Loaded In Activated Carbon And Its Application Of Reducing Greenhouse Gases By Dry Reforming Carbon Dioxide

The high concentration of greenhouse gases causes the greenhouse effect and results in global temperature rising,which lead to a series of ecological security issues.Currently,the concentrations of greenhouse gases such as CO₂,CH₄,and N₂O have risen to the highest level in nearly a century,and the treatment of greenhouse gases has become a common issue faced by human society today.CO₂dry reforming with CH₄（DRM）technology can not only consume CO₂and CH₄simultaneously under the atmospheric pressure,but also produce the syngas（CO+H₂）,which can be used as the raw materials of synthesizing alcohol,ether,alkenes,alkanes and other chemical products,effectively reducing CO₂and CH₄emissions and safeguarding ecological safety.At present,the limitations of the application of CH₄-CO₂reforming is the catalysts with low cost,high activity and strong carbon resistance.This research mainly focuses on preparing a Ni-based catalyst by loading active metal Ni on activated carbon using the impregnation method and modifying it with EDTA.As a result,a series of Ni-AC-E core-shell structural catalysts for CO₂dry reforming were synthesized.The experimental results showed that Ni₁₅-AC-E₃catalyst possessed the most excellent CH₄and CO₂conversions of 90.91%and 97.46%at850^oC,especially only a negligible decrease in conversions after 72 hours test.XRD,XPS,and TG-DTG characterization demonstrated that the addition of EDTA improved the physical structure of the catalyst and introduced nitrogen-containing functional groups that enhanced the basicity of the catalyst,improved the adsorption of the reaction gas,and accelerated the activation and dissociation of the reaction gas.The reaction mechanism and kinetics of dry reforming of methane over Ni₁₅-AC-E₃catalyst was studied.The action mechanism of methane and carbon dioxide on catalyst surface was discussed through FTIR experiment.In addition,the kinetic experiment data were fitted by different models such as PL model,ERⅠmodel,ERⅡmodel and LH model.The LH model demonstrated the highest correlation coefficient,clearly demonstrating the changing regularity of the reaction gas at different reaction temperatures.The activating energy were displayed as E_a=73.62k J/mol,ECO₂=44.92k J/mol and ECH₄=53.57k J/mol.To further improve the catalyst’s performance,an auxiliary metal-Mo,was added to the Ni-based catalyst to prepare a bifunctional catalyst and investigate its catalytic performance.CH₄and CO₂conversions over Ni₂Mo₁-AC-E₃reached 91.34%and97.53%at 850^oC.The addition of Mo could keep CH₄and CO₂conversions at 68.41%and 72.53%,with a slight decreased of 1.81%and 2.32%after 25 h,which was higher than Ni₁₅-AC-E₃under 700^oC.The catalysts were characterized by XRD,XPS,and TEM,and results demonstrated that the addition of Mo not only formed the Mo-C structure,which enhanced the adsorption capacity of the carrier to the reaction gas,but also reduced the generation of carbon accumulation and effectively inhibited the sintering of Ni agglomerates at high temperatures,thus improving the catalytic performance and reducing the energy consumption of the reaction.