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Combustion of chlorinated hydrocarbons in catalyst‐coated sintered metal fleece reactors

2003; Wiley; Volume: 78; Issue: 2-3 Linguagem: Inglês

10.1002/jctb.725

1097-4660

K Everaert, M. Mathieu, Jan Baeyens, Etienne F. Vansant,

Environmental remediation with nanomaterials

Abstract Incinerators emit chlorinated hydrocarbons, such as polychlorinated benzenes (PCBz) and phenols (PCPh), polychlorinated biphenyls (PCB) and polychlorinated dibenzodioxins and furans (PCDD/F), as very dilute streams. High temperatures (>1000 °C) are required in traditional oxidizers. From an energy‐saving perspective and to avoid de novo synthesis of PCDD/F, exhaust gas clean‐up must be performed at low temperatures (250–350 °C). Catalytic combustion can be applied in this temperature range and different reactor layouts are used (eg monoliths, honeycomb). The present investigation uses a novel catalyst‐coated sintered metal fleece. Thin metal fibers are sintered (non‐woven) to fleece of various thickness, structure and porosity. V–Ti–W catalysts are examined. The paper will briefly review the catalyst coating method suitable to provide a structured fleece reactor with adequate characteristics. Experiments were carried out in the temperature range of 260–340 °C with various hydrocarbons injected in a carrier air stream. The experimental investigations demonstrated: (i) that the conversion of the hydrocarbons (volatile organic compounds, VOC) is independent of the oxygen concentration, corresponding to a zero‐order dependence of the reaction rate; (ii) that the conversion of the hydrocarbons is a first‐order reaction in the VOC; (iii) that the oxidation of the VOC proceeds to a greater extent with increasing temperature, with chlorine substitution enhancing the reactivity, and (iv) that the reaction rate constant follows an Arrhenius‐dependence with activation energies between 37.3 and 58.4 kJ mol −1 . An assessment of the results leads to a model expression with kinetic reaction control. This model can be used in a scale‐up strategy. © 2003 Society of Chemical Industry