Hydrogen Rich Gas Production in a Diesel Partial Oxidation Reactor with HC Speciation

In the present work, the partial oxidation of diesel (US07), rapeseed methyl ester (RME) and low temperature Fischer - Tropsch synthetic diesel (SD), almost 100% paraffinic, was investigated for the purpose of hydrogen and intermediate hydrocarbon species production over a prototype reforming catalyst, for the potential use in hydrocarbon selective catalytic reduction (HC-SCR) of nitrogen oxide (NO_x) emissions from diesel engines. The presence of small amounts of hydrogen can substantially improve the effectiveness of hydrocarbons in the selective reduction of NO_x over lean NO_x catalysts, particularly at low temperatures (150-350°C). In this study, the partial oxidation reactor was operating at the same input power (kW), based on the calorific values of the fed fuel. Hydrogen production was as high as 19%, from the partial oxidation of SD fuel, and dropped to 17% and 14% for RME and US07 diesel, respectively. In conjunction with the hydrogen production, the short chain HC species (C1 - C6) produced by the partial oxidation reforming of the respective fuels were measured. The results show that US07 diesel produced more short chain HCs collectively than the other respective fuels, with SD producing the least. Based on literature, the fact that a hydrogen-rich gas was produced with inherent short-chain HCs; there can as a result be an influential positive effect on HC-SCR NO_x reduction activity when the reformates of the fuels are used as reductants in real diesel engine exhaust, more so for SD. Furthermore, the reformate gas can be directly used during passive HC-SCR over lean NO_x catalysts and eliminates the need for external fuel injections (active control) and therefore offers a fuel economy benefit.