The Preparation Of NiO/ZrO₂ Catalyst And Its CO₂ Methanation Performance

The massive emissions of CO₂ have many negative impacts on the ecological environment,but at the same time CO₂ is also a resource.It can be converted to other carbon resources by thermochemical conversion.Since the activation of CO₂ is very difficult and requires the use of catalysts,this paper focuses on the catalytic hydrogenation of CO₂ and discusses the catalytic hydrogenation performance of NiO/ZrO₂ catalysts.In this paper,the carrier is prepared by coprecipitation method,and Ni-based catalyst is prepared by impregnation method for CO₂ catalytic hydrogenation reaction.The effects of NiO loading,catalytic reaction temperature on the performance of the catalyst,and the addition of different additives were investigated to investigate the effect on the catalyst structure and catalytic performance.The physicochemical properties of the catalyst were tested by XRD,BET,TEM,H₂-TPR,CO₂-TPD and XPS characterization techniques,and the performance of the catalyst was evaluated by introducing a mixture of H₂/CO₂ into the self-assembled reactor.The catalyst was studied using ZnO as a carrier and an auxiliary agent.The CO selectivity of the NiO/ZnO catalyst was above 90%,and the selectivity of CH₄ was low.Adding to the zirconium dioxide as an auxiliary agent can change its phase state,so that NiO in the catalyst is not easily reduced.The results show that the addition of ZrO₂ can control the product selectivity of CO₂ catalytic hydrogenation.Studies on NiO/ZrO₂ catalysts have found that the catalyst has good activity at 350°C.The calcination temperature of ZrO₂ carrier was studied.ZrO₂ with monoclinic phase and amorphous phase could be obtained at different calcination temperatures.After the support additive Mg was introduced,the zirconium dioxide became tetragonal phase.The effects of different phase ZrO₂ on the catalytic activity were investigated.The results show that MgO enters the crystal lattice of ZrO₂ and transforms it from monoclinic crystal to tetragonal phase ZrO₂,which makes NiO easier to be reduced and loaded with Ni.ZrO₂ is more easily reduced.After adding MgO,the basic position of the catalyst is increased,and the ability to absorb and desorb CO₂ is enhanced.The catalytic activity sequence NiO/Mg_0.1Zr_0.9>NiO/m-ZrO₂>NiO/Mg_0.1Zr_0.9?mechanical mixing?>NiO/a-ZrO₂.It was found that ZrO₂ was converted into tetragonal phase ZrO₂ by using different additives Ca,Mn,Zn and Mg,respectively.The catalytic activity sequence was NiO/Mg_0.1Zr_0.9>NiO/Mn_0.1Zr0.9>NiO/Ca_0.1Zr_0.9>NiO/Zn_0.1Zr_0.9,the catalyst obtained by adding Mg promoter has better catalytic activity,CO₂ conversion rate is82.2%,methane selectivity is 71.1%,CO selectivity is 28.8.%.In summary,based on the NiO/ZrO₂ catalyst,it can be used for the catalytic hydrogenation of CO₂,and the catalyst with better catalytic activity can be obtained.The tetragonal phase ZrO₂ obtained by Mg modification has the best effect.