Preparation Of Nano-carbon Composite Transition Metal Oxide Catalyst And Its Catalytic Oxidation Of Formaldehyde

As one of the top ten challenges facing mankind in the 21st century,air pollution has seriously deteriorated our living environment and health.Formaldehyde,as one of the most common volatile organic pollutants,widely exists in various furniture decoration materials and adhesives.It is characterized by slow release and low concentration.The person that contacts formaldehyde for a long time can cause serious respiratory tract disease,bring about neurasthenia and haemal disease,wait like leukaemia.This paper aims at the complete degradation of formaldehyde by catalyst materials with high efficiency,low cost and low energy consumption.The thermal oxidation degradation of formaldehyde by one or more transition metal oxide catalysts supported by different carbon carriers has been prepared and compared.Good results have been achieved.In this paper,The bimetallic catalysts Mn-Co/CNTs and Mn-Ce/NCNT were prepared by using CNTs and NCNT as catalyst supports respectively.Mn-Co/CNTs catalyst active component manganese element mainly exists in MnO₂?+4?,cobalt element mainly exists in CoO?+2?.The evaluation on the catalytic oxidation performance of formaldehyde showed that the increase of Mn³⁺content was conducive to the improvement of catalyst activity,and the appropriate increase of Co²⁺ratio was also conducive to the improvement of catalyst activity,but it should not be too high,otherwise the catalyst activity would be seriously reduced.The best 3Mn-1Co/CNTs catalyst has formaldehyde removal rate and CO₂ selectivity more than 95%under condition of 160?,GHSV 3×10⁴ mL·h^-1·g^-1,and 100ppm HCHO.After exchanging Co for Ce,Mn-Ce/NCNT catalyst was prepared,the active component particles formed are smaller,about 5nm.The presence of manganese element mainly are Mn₃O₄,while Cerium element mainly exists in CeO₂?+4?.The catalyst has the betterr catalytic oxidation activity,compared to Mn-Co/CNTs catalyst,such as at 120?,3Mn-1Co/NCNT,the degradation efficiency of formaldehyde reached more than 95%.In 72h continuous operation,the removal rate of formaldehyde and the selectivity of CO₂ are maintained at more than 95%,which shows good stability.Four carbon materials,graphite,graphene,CNTs and NCNT were used to prepare catalyst materials with different MnO₂ contents under the impregnation and oxidation of potassium permanganate at different concentrations.Through the catalytic oxidation evaluation of formaldehyde?100ppm?on the catalysts of these four different carbon carriers,the appropriate nano-carbon carrier and MnO₂ load were preliminarily screened out:Catalysts supported by graphene and nitrogen-doped carbon nanotubes had the best formaldehyde removal efficiency at room temperature.In terms of CO₂ selectivity,MnO₂/NCNT has certain advantages over graphene carrier catalysts.40%MnO₂/NCNT catalyst showed high catalytic oxidation activity under 100?,which in the 72 h of continuous reaction of formaldehyde removal rate and CO₂selectivity to remain above 95%,and shows good stability,better than all the catalyst materials,has a good application prospect.