Study On Catalysts Applied To CO Of Low Temperature In Confined Spaces

The catalytic oxidation of CO at low temperatures is a hot direction for research,and low temperature catalysts can be used in closed space CO elimination,gas masks,closed cycle CO₂ lasers and in the device of purging gas.Co₃O₄ exhibits excellent activity in low temperature catalysis,while CeO₂ has high capacity of oxygen storage,and both of them have higher advantages in price than precious metal catalysts.Therefore,the CeO₂-Co₃O₄ catalyst were studied,and the CO catalysts with high activity at low temperature were prepared by changing the preparation conditions and adding polyethylene glycol,noble metal Pt,metal oxide MoO₃.The results are as follows:（1）A series of CeO₂-Co₃O₄ catalysts were prepared by co-precipitation method.The effects of different CeO₂ contents on the activity of the catalysts were studied,and the effects of space velocity and CO concentration on the optimal CeO₂ content catalyst were also investigated.The results showed that the activity of the catalyst with 6%loading of CeO₂ was the best,and the complete conversion temperature T₁₀₀was 60℃.With the increase of space velocity,the catalytic efficiency of the catalyst at the same temperature decreased.When the concentration of carbon monoxide was high,the catalyst could still maintain high catalytic efficiency.The effects of preparation conditions on the activity of 6CeO₂-Co₃O₄ catalyst were investigated.The optimum calcination temperature was 400℃and the centrifugal speed was 6000 r/min.（2）The effect of polyethylene glycol on the activity of the catalyst was investigated.The 6CeO₂-Co₃O₄ catalysts with different polyethylene glycol were prepared and the catalytic efficiencies at different temperatures were tested.The results showed that the catalyst with addition of polyethylene glycol 4000 had the best activity,and the complete conversion temperature T₁₀₀ was 70℃.The catalysts with different amounts of polyethylene glycol 4000 addition were also prepared.The activity was tested.The results showed that when the amount of polyethylene glycol was 2%,the catalytic activity was the best.（3）A series of Pt-CeO₂-Co₃O₄ catalysts were prepared by co-precipitation method.the effects of adding noble metal on the catalysts were explored.The Pt-6CeO₂-Co₃O₄ catalysts with different Pt contents were prepared and the catalytic efficiency at different temperatures was tested.The 1%Pt-CeO₂-Co₃O₄ catalyst had better catalytic efficiency.The specific surface area test results showed that the oxygen defects may be covered by the doping of Pt,resulting in a decrease in the specific surface area and the average pore size in the catalyst,making the catalyst activity unsatisfactory.（4）The MoO₃-6CeO₂-Co₃O₄ catalysts were prepared by co-precipitation method and impregnation method.The results showed that after the addition of MoO₃,the low temperature performance of the catalyst was improved.when the content of MoO₃was 5.61%,the low temperature performance of the catalyst was the best,and its efficiency was up to 97%at 40℃.H₂-TPR test results showed that after the doping of MoO₃,the reduction peak of the catalyst was moved to low temperature.The anti-sulfur performance of the catalyst was also investigated.The results showed that MoO₃-6CeO₂-Co₃O₄ catalyst had poor sulfur resistance and could not form selective adsorption and catalysis of CO and SO₂,so it could not show the sulfur resistance of MoO₃ in the SCR reaction.