Producing a monolithic catalyst for the catalytic oxidization of dioxins by comparing extrusion and coating methods

Abstract

Coating and extrusion methods were compared in lab-scale catalytic decomposition of chlorobenzene (CB) to increase utilization of the powdered VW/TiO₂ catalyst. As a result, when the VW/TiO₂ was coated on a cordierite by silicone gel, the obtained monolithic catalyst removed 1449 ppm g⁻¹ (per gram of actual coated VW/TiO₂) of CB at 300 °C. Since the monolithic catalyst obtained a smaller conversion (68%) than the powdered VW/TiO₂ (87%), a mechanism investigation revealed the reasons. On one hand, the binder silicon covered oxygen vacancies and decreased the reductive capacity of the VW/TiO₂. On the other hand, the coating process, such as dispersion in gel and afterward calcination, also decreased the redox property. However, these disadvantages were inevitable, and the put-forward coating method still showed a better catalytic performance than a commercial honeycomb catalyst, which only removed 237 ppm g⁻¹ of CB at 300 °C. This work supplies various potential coating methods for researchers, who would like to increase the applicability of their newly developed catalysts.