Research On Carbon Dioxide Capture And Utilization Based On New Dual-function Catalyst

The content of CO₂ in the atmosphere has risen sharply,and the world is facing major ecological and environmental problems.CO₂ capture and utilization（CCU）is regarded as the most effective way to achieve low carbon emission reduction.The core problem of CCU technology is to find catalysts with large CO₂ capture capacity,strong durability and high efficiency conversion of captured CO₂.Therefore,the comprehensive study of the CO₂ capture and conversion bifunctional catalyst is of great significance to the realization of the natural carbon cycle.CaO was prepared from analytically pure Ca（NO₃）₂·4H₂O,Ca（Cl O）₂ and Ca Cl₂ as raw materials and compared with commercial CaO.Scanning electron microscope（SEM）and isothermal nitrogen adsorption-desorption（BET）were used to characterize and analyze the surface morphology and pore structure of CaO.Thermogravimetric analysis（TGA）was used to measure the CO₂ adsorption performance of CaO materials.The results show that CaO prepared from Ca（NO₃）₂·4H₂O has a large adsorption capacity for CO₂,and after 10 CO₂ adsorption-desorption cycles,the adsorption capacity of CaO for CO₂ is maintained at 88.2%,with good thermal stability.In order to explore the effect of calcium-based precursors on the activity of Ni/CaO dual-functional materials（DFM）,analysis of pure Ca（NO₃）₂·4H₂O,Ca（CH₃OO）₂·H₂O,Ca Cl₂ and Ca（Cl O）₂ are CaO precursors In order to prepare Ni/CaO-DFM(W_Ni=10%),the properties of four Ni/CaO-DFM for CO₂ conversion were investigated.Ni/CaO-DFM was characterized by thermogravimetric analysis（TGA）,scanning electron microscope（SEM）,X-ray diffraction analysis（XRD）,isothermal nitrogen adsorption desorption（BET）,temperature-programmed reduction（H₂-TPR）,etc.The results show that the Ni/CaO-DFM（R1）prepared with analytically pure Ca（NO₃）₂·4H₂O as a CaO precursor has a well-developed pore structure,and the adsorption capacity of CO₂ is significantly higher than that of other samples,and the Ca CO₃ generated by R1 is the easiest Decomposition is conducive to the recycling of Ni/CaO-DFM.At the same time,the dispersion of NiO in R1,which is in close contact with CaO,is improved,and the activity of Ni is enhanced,which is beneficial to increase the production of CO.The fixed bed experiment showed that the conversion efficiency of R1 to CO₂ in the four Ni/CaO-DFMs reached a maximum of 30%,and the CO output reached 0.514 mmol g^-1.R1 undergoes 10 CO₂ adsorption-desorption cycles,without obvious sintering phenomenon,and has strong durability,which will greatly reduce the cost of catalyst preparation.Using analytically pure Ca（NO₃）₂·4H₂O as a CaO precursor,Ni/CaO-DFM with Ni loadings of 2.5%,5%,10%,and 20%were prepared,and four Ni/CaO-DFM conversions were investigated CO₂ performance.Scanning electron microscopy（SEM）and isothermal nitrogen adsorption desorption（BET）were used to characterize and analyze the surface morphology and pore structure characteristics of the material.It was measured in a fixed-bed experiment that as the Ni loading increased,the CO output increased first and then decreased.The increase in Ni content increases the active sites of the material and improves the CO output.When the Ni loading is 20%,the relative content of CaO is reduced,the original porous structure is destroyed,and the CO₂adsorption capacity is greatly reduced,resulting in a decrease in CO production.5%Ni/CaO-DFM and 10%Ni/CaO-DFM have similar internal pore structures,which have similar effects on CO₂ catalytic conversion.Considering the essential problem of reducing costs and saving resources,the optimal loading of Ni-CaO catalyst is 5%.