Catalytic combustion of waste streams coming from the solvent recovery stage of a packaging industry

Esters and alcohols are widely used as solvents in the packaging industry. They contribute to the increase of VOCs (Volatile Organic Compounds) and, as such, it represents a serious air pollution problem that must be faced. To this end, two main strategies can be pursued: solvent recovery and/or incineration, the former being of course preferred. Solvent recovery mainly consists of an activated carbon plant, which adsorbes the post-printing exhaust solvents, and a distillation system, which separates the solvent recovered mixture. The waste streams coming from the solvent recovery stage need to be disposed, implying additional costs as well as safety issues. In this framework, an alternative solution is here proposed based on catalytic combustion of the waste streams. Catalytic combustion enables burning VOC at low temperatures, thus avoiding NOx formation. Furthermore, the catalyst allows total combustion without formation of unburnt hydrocarbons (UHC) and CO. Finally, catalytic combustion can be carried out at concentrations that are outside the flammability range, thus ensuring safe operation. In this work, we present results of catalytic combustion tests for two waste streams, namely the high-boiling-point stream and the azeotropic stream, coming from the distillation plant of the packaging industry Icimendue. The high-boiling-point stream is mainly constituted by ethyl alcohol (60 % vol.) and ethyl acetate (30% vol.). The azeotropic stream is mainly constituted by ethyl acetate (95 % vol.) (ethyl alcohol = 4.5 % vol.). A Pt-doped perovskite is used as the catalyst. Noble metal-doped perovskites have been successfully proposed for catalytic combustion of hydrocarbons [1-3]. The catalyst is supported over a monolith that allows reduction in pressure drop along with process intensification [4,5]. Experimental tests are performed in a lab-scale plant. The solvents are heated and evaporated prior to entering a tubular quartz reactor containing the monolith. The system reactor-plus-monolith is placed in a tubular electric oven equipped with a PID controller to perform tests at constant temperature and controlled heating rate. The gas mixture exiting the reactor enters an analysis system equipped with three modules for the online and continuous analysis of the main gas species (CO2 and CO by infrared detectors; O2 by a paramagnetic detector). Though catalytic tests, the effects of temperature, contact time and oxygen-to-solvent ratio are investigated.