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Treatment of Volatile Organic Compounds by a Regenerative Catalytic OxidizerLin, Chien-hung 24 July 2009 (has links)
Abstract
Isopropyl alcohol¡]IPA¡^and toluene are extensively used in industry as solvents. They are all highly toxic to animals and humans. Accordingly, IPA and toluene are strongly associated with problems of VOCs. In first step catalytic incineration was adopted to decompose IPA and toluene in laboratory, and the second step for a pilot-scale regenerative catalytic oxidizer ¡]RCO¡^were adopted to decompose mixture VOCs in real soil herein.
The screening test of catalytic activity and the influences of the operational parameters on IPA and toluene removal efficiencies were widely discussed through catalytic incinerations of IPA and toluene in laboratory. The more effective and cheaper catalysts through above discussions of catalytic incineration were selected. And they were utilized in an pilot scale RCO as follows to investigate their performance in VOCs oxidation and RCO operations in THC removal of contamination soils. The achievements of this study are summarized as follows:
¡]1¡^Cu/Mn and Cu/Co gravel catalytic incinerations of isopropyl alcohol
The results demonstrated that 10 wt% Cu0.6Co0.4 catalyst was the most effective because the CO2 yield reached 95 % under the following operating conditions; a temperature of 425oC, an inlet IPA concentration of 2500 ppm, an oxygen concentration of 21%, and a space velocity of 13500 hr-1. Additionally, the stability test results indicated that the 10 wt% Cu0.6Co0.4 catalyst exhibited excellent stability at both low and high conversion of IPA.
¡]2¡^20% Cu/Mn aluminum oxide catalytic incinerations of toluene
The conversion for toluene reached 95% when the Cu/Mn catalyst was used with a metal ratio of 1:1 and 20% loading at 350¢XC, an influent toluene concentration of 1000 ppm, oxygen concentration of 21%, a space velocity of 12000 hr-1, and relative humidity of 26%. The long-term test was proceeded for seven days at a constant influent toluene concentration of 1000 ppm, constant oxygen concentration of 21%, constant space velocity of 12000 hr-1 and constant relative humidity of 26%. The SEM results indicated the Cu/Mn catalyst was quite stable at 350¢J.
¡]3¡^RCO testing for a copper/manganese catalyst of gaseous toluene
The Cu/Mn (20wt%) catalyst was selected as the best one, because it converted 95% of the toluene at 400¢J. The results also indicating that the Cu/Mn catalyst was quite stable at 400¢J.
(4) RTO treatment of VOCs with SVE system
The conversion for VOCs reached 80% at 900¢XC, an influent VOCs concentration of 450-2000 ppm and a gas flow rate of 0.5 m3/min.The Thermal Recovery Efficiency¡]TRE¡^was approximately 86-90% in a RTO operated at 800-900¢J.
(5)RCO treatment of VOCs with SVE system¡]10 wt% Cu0.6Co0.4 gravel catalyst¡^
The 10 wt% Cu0.6Co0.4 gravel catalyst was the poverty active, because it converted 65% of the VOCs by SVE system operated at 650¢J.
(6)RCO treatment of VOCs with SVE system¡]20% Cu/Mn aluminum oxide catalytst¡^
The 20% Cu/Mn aluminum oxide catalytic was the best choice, because it converted 95% of the VOCs at 650¢J, an influent VOCs concentration of 450-10000 ppm and a gas flow rate of 0.5-1.5 m3/min. The SEM results indicated that the conversion of VOCs decay did not clearly vary at 650¢J, also indicating that the Cu/Mn catalyst selected was quite stable. The TRE was approximately 90% in a RCO¡]20% Cu/Mn aluminum oxide catalytic¡^operated at 650¢J.
(7)RCO treatment of VOCs with SVE system¡]20% Cu/Mn gravel catalytst¡^
The 20% Cu/Mn gravel catalytst was the best selection , because it converted 95% of the VOCs at 600¢J, an influent VOCs concentration of 450-10000 ppm and a gas flow rate of 0.5-1.5 m3/min. The SEM results indicated that the conversion of VOCs decay did not clearly vary at 600¢J, also indicating that the Cu/Mn catalyst selected was quite stable. The TRE was approximately 90% in a RCO¡]20% Cu/Mn gravel catalytic¡^operated at 600¢J.
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