Oxidation of VOC over cryptomelane catalysts: Doping with gold and alkali

• Type: Chapter or Part of a Book
• Date: 2016

Authors

Sónia Carabineiro (Author) FEUP; Santos V.P. (Author) Other; O.S.G.P. Soares (Author) FEUP; Manuel Fernando R Pereira (Author) FEUP; Órfão J.J.M. (Author) Other; Figueiredo J.L. (Author) Other

Book

Title: Volatile Organic Compounds: Occurrence, Behavior and Ecological Implications

Pages: 135-163

ISBN: 978-1-63485-390-3

Indexing

Scopus - 1 Citation

Other information

Authenticus ID: P-00Z-T8K

Abstract (EN): Volatile organic compounds (VOC) are hazardous environmental pollutants originated from different sources, such as petroleum refineries, fuel storage, motor vehicles, painting and printing activities. VOCs emissions are regulated due to their potential damages to human health and the environment. Catalytic oxidation to CO2 and H2O is an environmentally friendly technology for VOC abatement that needs low temperatures (around 250-500°C) and causes less NOx formation, compared to conventional thermal oxidation, which operates at higher temperatures (650-1100°C). Several catalysts have been used for this purpose. In this work, cryptomelane-type manganese oxides were tested for the oxidation of ethyl acetate and toluene, two common VOCs. Catalysts were synthesized by redox reaction under acid and reflux conditions. Different metals (cerium, cesium and lithium) were incorporated into the tunnel structure of cryptomelane by the ion-exchange technique. Gold was loaded onto these materials (1% wt.) by a double impregnation method. The obtained catalysts were characterized by X-ray diffraction, high-resolution transmission electron microscopy, energy-dispersive Xray diffraction and temperature programmed reduction. It was found that addition of Cs and Li to cryptomelane was beneficial for ethyl acetate oxidation, but addition of Ce is detrimental, which is related to the reducibility of the materials. Addition of gold does not improve the catalytic activity, and in case of Li and Cs modified samples, it has even an unfavourable effect. This effect can be related to the large gold particle size found for these samples, well known to be inversely related with catalytic activity. Addition of Li to cryptomelane was beneficial for toluene oxidation, but adding Cs and Ce was disadvantageous. Loading with gold also did not show considerable improvement, which may also be related to particle size effects. The activity for both VOCs abatement was correlated with sample reducibility.

Language: English

Type (Professor's evaluation): Scientific

No. of pages: 28