Mesoporous Composite Manganese Based Catalysts For VOCs Purification And Its Life Cycle Assessment

In recent years,the heavy pollution weather occurred frequently,VOCs as an important precursor of organic PM_2.5 and ozone formation,VOCs purification has received the widespread attention,the catalytic oxidation method as an important choice of industrial VOCs purification technology,its core is the production and research of the catalyst.The mesoporous metal oxide catalysts are widely used in VOCs purification because of their large specific surface area,special pore structure and controllable pore size.Based on SBA-15 as hard template agent was prepared mesoporous composite manganese catalyst,the catalytic combustion of VOCs such as formaldehyde,ethanol performance was evaluated,using XRD,BET,XPS technology carried out its characterization.Based on the experimental data,the life cycle evaluation of the catalyst products was carried out by using the mesoporous metal oxide catalyst and the supported catalyst as an example.The results are as follows:?1?The Cu/MnO_x catalysts prepared by the nano pouring method all reproduce the mesoporous skeleton structure of the regular SBA-15 molecular sieve,so they are all mesoporous catalysts.All samples had?-MnO₂ and Mn₂O₃ crystalline phases.After Cu addition,CuO and Cu₂O were formed,and the specific surface area and pore size of mesoporous catalysts were reduced.The addition of Cu increased the reduction strength of the mesoporous catalyst,and the two reduction peaks coincided.In addition to the 20%Cu/MnO_x catalyst,mesoporous Cu/MnO_x catalysts have good catalytic activity for formaldehyde.This is mainly due to the strong interaction between Cu-Mn,Cu is beneficial to the dispersion of metal Mn,reducing the reduction activation energy of Mn³⁺and Mn⁴⁺,has more O_ads,which is more conducive to oxidation reaction,thus improving the catalytic activity of formaldehyde.The decrease of the activity of 20%Cu/MnO_x formaldehyde may be due to the excessive addition of Cu to the collapse of the catalyst channel to counteract the increased activity of other parts,which shows a decrease in the activity of formaldehyde.The ethanol catalytic activity of the catalyst increased at low temperature,which was mainly related to the good low temperature reduction of the catalyst.However,with the increase of temperature,the activity of catalyst after Cu addition is lower than that of MnO_x catalyst,which may be caused by the decrease of specific surface area of Cu/MnO_x and the decrease of Mn⁴⁺.?2?The Zr/MnO_x catalyst prepared by the nano pouring method retained the mesoporous structure of SBA-15 molecular sieve,so they are all mesoporous catalysts.All the samples have the crystalline phase of?-MnO₂ and Mn₂O₃.ZrO₂ is generated after adding Zr.With the addition of Zr,the specific surface area of catalyst increased gradually,and the pore size changed little.In addition to 20%Zr/MnO_x catalyst,mesoporous Zr/MnO_x catalysts have good catalytic activity for formaldehyde.This is mainly because the addition of Zr improves the specific surface area of the catalyst,and the exposure of active Mn⁴⁺species is more,and it is more beneficial to the adsorption of oxygen molecules.20%the decrease of Zr/MnO_x formaldehyde activity may be due to the excessive addition of Zr,which results in the increase of the size of the catalyst molecular sieve.The catalytic activity of 20%Zr/MnO_x is slightly higher than that of MnO_x,which may be due to the larger specific surface area,Mn⁴⁺and O_ads of 20%Zr/MnO_x.The catalytic activity of other catalysts is smaller than that of MnO_x,which may be because the flocculation of ZrO₂ makes the reducing performance of MnO_x not improved,the content of Mn in the unit mass catalyst is reduced,the catalytic activity of the catalyst is reduced,and the activity enhancement caused by the specific surface area and Mn⁴⁺is not enough to counteract the activity of its descending,so the overall activity decreased.?3?The environmental impact of mesoporous metal oxide catalysts was evaluated by LCA.It was found that the main pollutants emitted by the catalyst were gas pollutants,and the main effects on the environment were fossil fuel consumption,climate change,acidification,human health and particle formation.The energy consumption is the main factor affecting the environmental performance of mesoporous catalyst.Therefore,appropriate to improve production technology,improve production equipment,especially oven and muffle furnace the performance of these high power high power consumption equipment to reduce the power consumption of production process for the preparation of resource saving catalyst is especially important.