| Carbon dioxide is the main cause of the green-house effect.Encouraged and driven by relevant policies issued by our country,the chemical engineering industry begins to pay increasing attention to sustainable development and environment-friendly economic growth.Ecological balance is also the focus of the chemical engineering industry.Carbon dioxide emission attracts people's attention all the time,however,the demanding task is how to efficiently convert carbon dioxide to useful chemical products.As we all know,carbon dioxide has a variety of properties that can be utilized.Carbon dioxide can be used as refrigerant for preserving foods,or be used to manufacture carbonated beverage,or serve as super-critical fluids.Moreover,carbon dioxide's reaction with other molecules like hydrogen,methane or water can be used to produce chemicals of high additional value?formic acid,formaldehyde,methanol,methane and so on?.And carbon dioxide hydrogenation is the most significant reaction,which attracts many experts'attention at present.Methane is the simplest hydrocarbon.It is the main component of natural gas and usually serves as the fuels for domestic life or transportation.Methane can also produce other products when reacting with other reactants.All in all,carbon dioxide methanation deserves our research,especially theoretical study on the reaction mechanism which can further guide practical application.This study mainly focuses on Ru2/?-Al2O3 catalysts for exploring the interaction between Ru cluster and?-Al2O3supporters.All calculations were based on density functional theory?DFT?by virtue of Vienna ab initio simulation package?VASP?.Spin-polarized calculations were performed.The PW91 generalized-gradient approximation functional of Perdew and Wang was employed for describing electronic exchange and correlation.The projected augmented wave?PAW?method was adopted to reflect the core-electron interactions.First,single Ru atom adsorbed on?-Al2O3 has been investigated to determine the most favorable adsorption site;then this paper studys Ru clusters'adsorption and the calculations indicate Ru clusters and?-Al2O3 support have strong interaction and Ru/?-Al2O3 can be used as excellent catalyst for carbon dioxide methanation.Ru2/?-Al2O3 is selected for the catalyst used to investigate reaction mechanism,for which not only reflect the interaction between Ru2 cluster and?-Al2O3 but also the interaction between Ru atoms of Ru2 cluster.The calculations on reaction mechanism show that direct dissociation of carbon dioxide is the main reaction path with energy barrier of 0.46eV. |
PDF Full Text Request