Catalytic Oxidation Assisted with Ozone for theAbatement of 1,2Dichloroethane

摘要

This study investigated the ozoneassistedcatalytic oxidation (ozonecatalyticoxidationprocess, OZCO) for the abatement of chlorinated volatile organic compound of1,2dichlorethane(DCEA) over Pt/Al2O3 catalyst. The DCEA is mainly used to produce vinylchloride monomer (VCM) which is a raw material for manufacturing polyvinyl chloride. Therelationships between the conversion of DCEA (XCE) and related major factors such asreaction temperature (T), space velocity (SV) and ozone concentration (CO3) were examined.Further, the formation of products and deactivation of catalyst were also discussed.The results indicate that the XCE is enhanced via the Pt/Al2O3. At the concentration of DCEA(CCE) of 430 ± 30 ppmv and gas flowrate(QG) of 525 L min1,the values of T of oxidationwithout ozone for 90% conversion without (TOX)and with (COX)the catalyst at SV =125,000 1/h are 925 and 640 K, respectively, while is 610 K for OZCO with CO3 = 200 ppmv.The final breakdown products of DCEA via COXconsist of significant amounts of CO2 andCl2, with little VCM and HCl. In the OZCO process, the T needed to reach the same XCEdecreases with the increase of CO3, such as T = 470 and 430 K with CO3 = 150 and 200 ppmvat XCE = 50% and SV = 125,000 1/h. Further, the XCE of OZCO at the same T is higher thanthat of COX.For example, at T = 600 K and SV = 125,000 1/h, the value of XCE of theformer with CO3 =150 ppmv and latter are 75 and 60%, respectively. This indicates that thepresence of ozone indeed assists with the efficiency for treating the DCEA. Furthermore, theintroduction of ozone into the catalytic oxidation of DCEA has distinct effects on the yields ofproducts. The yield of CO2 of OZCO is higher than that of COXwithout ozone. However,the ratio of total chlorine atoms of gaseous products to inlet chlorine atoms of OZCO is lessthan that of COXwithout ozone. Thus, it indicates that a large number of chlorinated