Investigation On The "Storage-Oxidation" Cycling Process For Indoor Benzene And Formaldehyde Removal

Benzene and formaldehyde are one of the common and most toxic indoor volatile organic compounds (VOCs). Long-term exposure to benzene and formaldehyde may cause adverse effects on human health. Significant efforts have been made to remove low concentration of indoor C6H6 and HCHO. In our previous work, a novel "storage-oxidation" cycling process was proposed for indoor C6H6 and HCHO removal over bi-functional catalysts. The process includes enrichment of low concentration of C6H6 or HCHO during the storage period at room temperature; and complete oxidation of the stored C6H6 or HCHO into CO2 and H2O at elevated temperatures. The key issues for application of this approach are prolonging the non-power-inputted storage time, lowering the regeneration temperature and utmost reducing the release of VOCs.On this basis, a series of research has been carried out and the results were summarized as follows:(1) We proposed a novel "storage-oxidation" cycling process operated at room temperature, with assistance of non-thermal plasma (NTP) in regeneration phase for stored C6H6 oxidation. High hydrophobic zeolite TS-1 was selected as the supporter. Compared with the thermal regeneration, the good humidity tolerance, non-benzene release, and low energy cost were achieved in the non-thermal air plasma regeneration, which providing a possible way for indoor benzene purification.(2) In order to enlarge the storage capacity of C6H6 and HCHO, the commercial activated carbon (AC) was applied the "storege-discharge" cycling process of C6H6 and HCHO removal. Temperature programed desorption showed that the HCHO storaged on AC was easily to desorb, thus most of the stored HCHO was oxidized into CO, while the C6H6 was deposit on the AC catalysts, leading to the low carbon balance during the cyclic process. The results indicate that carbon materials were not suitble for the "storege-discharge" cycling removal of C6H6 and HCHO.(3) CoMnOx catalysts were prepared by low temperature co-precipitation (CP) using Na2CO3 as precipitants, and investigated as catalysts for HCHO oxidation. TEM techniques were used to characterize the morphology of the samples. It was shown that aging temperature and aging time influence the morphology of CoMnOx. Adding Ag by different method and optimizing the loading content of Ag,100% conversion of HCHO into CO2 and H2O can be achieved at 75? over 3 wt% Ag/CoMnOx catalyst.