Highly Efficient Conversion Of Carbon Dioxide Into Formic Acid And Cyclic Carbonate Using Ninpore Catalyst

The great development of human economic society is based on the massive consumption of fossil fuels.As a consequence,two global problems,excessive emission of carbon dioxide and energy shortage,are becoming more and more serious.CO₂ as the main greenhouse gas causes global warming which has a series of bad influence on both environment and ecology.On the other hand,the energy shortage will not be conducive to the sustainable development of human society.How to reduce CO₂ in the atmosphere and transform it into something valuable is a hotspot in nowadays researches.CO₂ is often considered as a renewable C1 source due to its abundant,nontoxic and readily available.The effective way to solve these two problems is the utilization and converting of CO₂ into useful chemicals and fuels.Catalytic hydrogenation of CO₂ as well as conversion of CO₂ and epoxides to cyclic carbonates are both CO₂utilization technologies with industrial prospects.However,existing technologies have more or less drawbacks,such as using noble metal as homogeneous catalyst,high reaction temperature,difficult in separating products and so on.In this paper,we applied high-performance nanoporous nickel?NiNPore?which was prepared from Ni₃₀Mn₇₀ alloy and was easily recoveried and recycled for many times as catalyst for hydrogenation of CO₂ into formic acid?FA?as well as conversion of CO₂and styrene oxide to styrene cyclic carbonate.Thereby realized the utilization of carbon dioxide from different aspects.Initially,we tested different nickel catalysts in the hydrogenation of CO₂ into FA,results found that NiNPore exhibited high catalytic activity compared to other catalysts.Then experiments were conducted to investigate how catalyst loadings,hydrogen pressure,reaction temperature,reaction time and recycle of catalyst affect the reaction.86.6%yield of FA?selectivity>99%?was achieved in the presence of 1 mmol NaHCO₃?as CO₂ source?,22 mol%NiNPore,6 MPa H₂ and 10 mL water at 200 ? for2 h.Experiments also showed that NiNPore had high stability and still remained high catalytic activity after five recycles,and 90.5%yield of FA was afforded.Further expanding the scope of the feedstock was carried out with various bicarbonates and carbonates as CO₂ sources.The yield of FA was 92.1%,86.6%,76.6%and 71.2%respectively when using KHCO₃,NaHCO₃,K₂CO₃ and Na₂CO₃ as CO₂ source.Results also found that hydrogenation of bicarbonates were more easily than that of corresponding carbonates,this might be because cations of bicarbonates had an effect on FA yield.Then a plausible mechanism for the hydrogenation of CO₂ to FA over NiNPore was proposed.At last,we also tested the possibility of conversion of CO₂ and styrene oxide to styrene carbonate using NiNPore catalyst,and the effects of co-catalyst,CO₂ pressure,reaction temperature and reaction time were investigated.The yield?detected by NMR?of cyclic carbonate was 93.1%in the presence of 100 mmol styrene oxide,17 mol%NiNPore,0.46 mol%TBAI,and 3 MPa CO₂ at 200 ? for 2 h.