Catalytic decomposition of ozone in the presence of water vapor

Abstract

The catalytic decomposition of ozone in the presence of water vapor at the relative humidity (RH) of about 90 % was investigated by using a tubular fixed-bed reactor. The performance tests and reaction kinetic studies were conducted for catalyst, i.e., Pt/gamma-Al2O3 (symbolized as Dash-220). The experiments were carried out at various constant reaction temperatures (298 similar to 323 K) and space velocities (24,000 similar to 44,000 hr(-1)). About 75 % decomposition efficiencies of ozone with inlet concentration of about 0.17 mol/m(3) was achieved at catalyst contact time of 015 sec (space velocity of 24,000 hr(-1)), reaction temperature of 323 K and RH of about 90 % for the Dash-220 catalyst. However, about 97 % decomposition efficiencies of ozone without the presence of water vapor at the same reaction conditions. The results indicated that the Dash-220 catalyst with the presence of water vapor gave lower performance of ozone decomposition than without the presence of water vapor can be achieved at the same reaction conditions. For the reaction kinetics, it was found that the pseudo-first-order chemical reaction rate equation was appropriate for the catalytic decomposition of ozone in the presence of water vapor investigated in this study. The apparent activation energies for the decomposition reaction of ozone using the Dash-220 catalyst in the presence of water vapor at RH of 90 % is 19.32 kJ mol(-1). The corresponding pre-exponential factor is 0.0041 mol/(s g-catalyst (mol/m(3))).