Storage and Oxidation of Oxygen-Free and Oxygenated Hydrocarbons on a Pt–Pd Series Production Oxidation Catalyst

Abstract

Within the Research Cluster of Excellence “Tailor-Made Fuels from Biomass” at RWTH Aachen University, novel fuels from biomass for internal combustion engines are investigated. The new fuels tend to soot less, which allows to increase exhaust gas recirculation for reduction of nitrogen oxides (NOx) emissions. This increases the emissions of unburnt hydrocarbons (HC), while the composition of the HC emissions changes because of the changed fuel composition. The impact of 16 different oxygen-free and oxygenated hydrocarbons (1-octanol, di-n-butyl ether (DNBE), 2-butanone and ethanol as examples for bio-derived fuels; toluene and n-heptane as examples for conventional fuels’ components; propane, propene, ethane, ethene, ethyne, methane, n-butane, isobutane, n-pentane and 2-propanol as HC known to be in exhaust gases) on a series production Pt–Pd/Al2O3 oxidation catalyst on a cordierite substrate has been investigated regarding adsorption and temperature programmed oxidation (TPO). In general, due to higher polarity oxygenated HC are stronger adsorbed than oxygen-free ones. For 1-octanol, an extraordinary high adsorption could be observed associated with vigorous exothermal oxidation reaction during TPO. Additionally, the temperature programmed desorption of 1-octanol and ethanol has been investigated by Diffuse Reflectance Infrared Fourier Transform Spectroscopy (TP-DRIFTS). Adsorbed alcohol species as well as oxidized products were demonstrated to be present.