Preparation Of Cobalt Based Bimetallic Catalyst And Its Catalytic Performance For Low Temperature Oxidation Of CO

The rapid development of society has made the environmental problems more and more serious.In productive life,even a small amount of CO can cause great hazards to catalysts and human health.To this end,how to achieve efficient CO removal has received extensive attention from numerous scholars.Thermo catalyst technology as an effective means to eliminate CO is gaining favor among researchers,how to develop a highly active and low-cost Co catalyst appears to be of paramount importance.In this paper,using XRD,SEM,TEM,XPS,H2-TPR,O2-TPD and nitrogen adsorptiondesorption tests,the relationship between the physical and chemical properties of Co3O4 catalysts and metal(Mn,Ce,La and Cu)doped Co based catalysts was studied.The effects of different preparation methods of Mn-Co catalysts on the catalytic activity of CO were discussed.The main conclusions of this work are as follows:In the first part,50MCo(M=Mn,Ce,Cu,La)catalysts doped with Co3O4-R metal were synthesized by simple template method using ZIF-67(Zeolitic Imidazolate Framework-67)as precursor.The results show that the reaction temperature(T100)corresponding to the conversion of 100%CO was 95℃ when the space velocity of 50MnCo catalyst was 36,000 mL gcat-lh-1,and the reaction temperature is 25℃ lower than that of the undoped Co3O4-R.Kinetic experiments show that the lower CO reaction energy barrier on 50MnCo catalyst is more prone to oxidation.The introduction of Mn and Ce species promoted the oxidation of CO catalyzed by Co3O4,while the introduction of Cu and La species reduced the content of surface-active species of the catalysts,thereby decreasing the reaction activity.In the second part,MnCo composite bimetal oxides with different content of Mn species were prepared by the same template method,and the effect of Mn species content on catalytic CO oxidation activity was investigated.At the same space velocity,20MnCo T100=80℃ exhibits high catalytic activity for CO.This is because the surface of 20MnCo is rich in Co3+,Oads and strong oxygen activation ability.In addition,in the presence of 0.4%water vapor in the reaction gas,the T100 of Co3O4-R is 145℃,while the T100 of 20MnCo is 120℃,which maintains stable catalytic activity after 50 hours,The introduction of Mn species inhibits the competitive adsorption dissociation of water molecules and reduces the formation of hydroxyl groups on the surface of the catalyst.This provides a scheme for subsequent improvement of water resistance and stability of CO catalysts.In the third part,MnCo-LDO-T catalysts doped with different Mn species and calcined at different temperatures were prepared by a simple co-precipitation method,and their effects on the catalytic activity of CO reaction were discussed.The results showed that the reaction performance of 5MnCo-LDO-250 and Co3O4-C at T100=30℃and T100=70℃ at the same space velocity has been greatly improved compared with the catalysts prepared by the template method.The utilization rate of Mn species has was greatly improved,and the catalytic stability remains high after 50 hours of CO reaction.The conversion rate of 5MnCo-LDO-250 catalyst is much higher than that of Co3O4-C in the presence of 0.4%water vapor in the CO mixture,and the conversion of 100%CO was maintained for 100 hours.