Hydrogenation Of Carbon Dioxide To Synthetic Fuel And Its Thermodynamic Analysis

The conversion of CO₂ as a carbon source to fuel through hydrogenation and reduction is considered to be the most effective way to utilize CO₂.At present,copper-based catalysts have good catalytic effects on CO₂ catalytic hydrogenation.In addition,in recent years,the unique structure properties of single atom catalysts?SACs?have been widely used and attracte the attention of scholars.Based on density functional theory,the adsorption state of related species,the change of reaction potential energy and the reaction heat during the hydrogenation of CO₂ over modified copper-based catalysts were studied.The main results include the following:?1?By studying the conversion process of hydrogenation of H/OH and CO₂on the surface of Cu?111?,it was found that the reaction of CO₂ with different hydrogen species yielded different product results.HCOO species could be easily obtained by reaction with H,and COOH species could be easily obtained by reaction with OH,and finally CO molecule could be obtained.?2?By studying the adsorption state of related species in the process of CO₂hydrogenation,it was found that the adsorption state of species on the catalyst surface did not change significantly at the active site of Si-doped Cu.Carbon dioxide synthesized methanol via HCOO pathway on the catalyst surface,and CO was also prone to reverse reaction under Si/Cu?111?.The main transformation pathway of CO₂on Si/Cu?111?surface was:CO₂?HCOO?HCOOH?H₂COOH?H₂CO?CH₃O?CH₃OH,among them,the energy-demanding step were HCOOH+H?H₂COOH.Compared with Cu?111?plane,Si doping reduced the activation energy barrier from1.423 eV to 1.298 eV,which enhanced the catalytic activity of Cu site.And Si doping was not conducive to the carbon insertion reaction to synthesize C-C bond,while the doped Copper-Zinc alloy was favorable for the reaction in kinetics and thermodynamics.?3?The electrocatalytic hydrogenation of CO₂ over graphene supported monoatomic copper catalyst?G-Cu?,metal dimer catalyst?MN-C,Copper alloy?and graphene supported monoatomic copper catalyst?Gv-Cu?was studied and the possible energy-demanding step was determined.The binding ability of graphite carrier to metal ensures the stability of structure.And the catalytic activity of Gv-Cu was lower than that of G-Cu,and the final synthesis of formic acid was desorbed from the catalyst surface.The methane product synthesized on the surface of G-Cu was desorbed from the catalyst.On the surface of metal dimer MN-C catalyst,the stability of catalyst configuration can improve the activity of metal sites.The stability of CuZn-C catalyst is less than that of ZnCu-C catalyst.In addition to CuCo-C,CuRh-C,CuZn-C and ZnCu-C have high catalytic effect on the hydrogenation of CO₂,which opens up a new way for the development of efficient catalytic materials for carbon dioxide reduction.The activation of CO₂ molecule is related to the binding ability of O atom to metal sites.In addition,it is found that the surface of charged G-Cu catalyst is more conducive to the adsorption of CO₂ on the surface.