Study On Purification Of Formaldehyde By Zeolite And Its Supported Catalyst At Room Temperature

Formaldehyde pollution caused a series of human health problems and environmental safety issues.In the packaging industry,formaldehyde pollution occurred in the ink printing,pallet transportation and other links,and its purification methods had always been concerned by people.Zeolite had many advantages such as selective adsorption,high thermal stability,a large specific surface area when purifying formaldehyde by adsorption or catalytic oxidation.Temperature had always been an important factor affecting the purification effect of formaldehyde.Although high temperature conditions improved the purification effect of formaldehyde,it increased energy consumption and cost and inconvenient to operate.Whether it can effectively purify formaldehyde at room temperature is very important in practical applications.Therefore,zeolite was used as the main body to purify formaldehyde by adsorption method and catalytic oxidation method at room temperature.This article discussed the purification effect of different types of zeolite s on formaldehyde,analyzed the effects of different metal modifications on the adsorption performance of zeolite,and studied the performance and mechanism of zeolite supported manganese oxide catalytic oxidation of formaldehyde.The main conclusions are as follows:(1)This article compared the purification performance of three common zeolites HBEA,HY and HZSM-5 at room temperature for formaldehyde,and analyzed the key factors affecting the adsorption performance of zeolites.The experiment showed that the HY with super cage structure and larger pore size had the highest formaldehyde removal rate in the three zeolites,reaching 93.5%.(2)The article explored the purification performance of zeolite modified by cobalt metal,manganese metal and cerium metal on formaldehyde at room temperature and explored the effect of metal modification on the adsorption capacity of zeolite.Compared with the unmodified zeolite,the removal rate of formaldehyde by cobalt metal and cerium metal modified zeolite decreased by 2.5%and 8.3%,respectively,and the removal rate of formaldehyde by manganese metal modified zeolite increased by 30%.(3)In the research of purifying formaldehyde by catalytic oxidation method,low-cost manganese oxide was used as the catalytic component.In-situ synthesis method was used to prepare Mn O_x/HZSM-5 catalytic oxidation of formaldehyde at room temperature.The results showed that Mn O_x/HZSM-5 had good catalytic activity at room temperature.Compared with HZSM-5,Mn O_x/HZSM-5 increased the removal rate of formaldehyde in dynamic test and regeneration test by 62%and 52%respectively after660min dynamic test and five regeneration tests.The formaldehyde removal rate remained at 90%after1020 minutes of dynamic testing,and 91%removal rate after five regeneration tests.In the static test,the removal rate reached 97%and the conversion rate of formaldehyde reached 92%.The preparation method of Mn O_x/HZSM-5 catalyst was simple,cheap,rich in resources,highly catalytic activity at room temperature,and had many advantages in practical applications.(4)The mechanism of oxidizing formaldehyde catalyzed by Mn O_x/HZSM-5 was analyzed,and the study found that formaldehyde oxidation was mainly divided into the adsorption and storage of formaldehyde,the preliminary oxidation of formaldehyde and the deep oxidation of formaldehyde.It was initially oxidized into intermediate products such as formate or carbonate,and finally the intermediate products were deeply oxidized into carbon dioxide.