Pd/γ-Al2O3 catalysts on cellular supports for VOC vapor neutralization

Abstract

The results from investigating the influence of temperature, concentration, and flow rate on the catalytic oxidation of vapors of volatile organic compounds (VOCs) in the presence of Pd/γ-Al2O3 catalyst on cellular supports are presented. The activity of Pd/γ-Al2O3 catalysts on ceramic and metal monolith supports with a cellular structure during the catalytic neutralization of VOC (ethanol, ethyl acetate) vapors under laboratory conditions was determined, and the most stable catalyst for the preliminary study of a large batch was chosen. A pilot unit was created to test a large batch of cellular monolith catalyst in neutralizing VOC vapors under conditions of flexographic production. It was established that a high rate of conversion (> 99 %) was achieved for VOC concentrations of 0.5 g/m3 at space velocities of up to ∼104 h−1, and for VOC concentrations of 5.0 g/m3 at space velocities of up to ∼5 × 105 h−1. The change in the activity of the catalysts on metal (nickel alloyed by aluminum) and ceramic cellular supports in service was investigated. After 300–500 min of operation, virtually complete deactivation of catalyst on a metal support was observed, accompanied by the formation of nickel oxide and acetate. Pilot unit tests with catalyst on cellular supports having a volume of 14.5 l in neutralizing the ventilation exhausts of flexographic production confirmed the possibility of more than 90% conversion at VOC concentrations of ∼0.1 g/m3 and more than 97% at VOC concentrations of over 1 g/m3. A consistently high conversion of VOC was observed during a 100 h test of the pilot unit. A system for recovering the heat released during VOC oxidation lowers the operating costs of the pilot unit.