Reaction Profiles during Exhaust-Assisted Reforming of Diesel Engine Fuels

Abstract

On-board hydrogen production by exhaust-assisted fuel reforming offers a potential route to diesel emission control. In this study, different reformer configurations with the same catalyst composition were tested, as well as three types of diesel engine fuel, under conditions designed to simulate low-and high-load engine operating modes. The reforming efficiency was dependent on the fuel type and followed the general trend of bioethanol > rapeseed methyl ester > lowsulfur diesel fuel. In each case, a characteristic axial temperature profile was established in the catalyst. The profile can be deconvoluted into three phases, corresponding to the consecutive occurrence of combustion, steam reforming, and water-gas shift. The relative contribution of each process not only responds to changes in the inlet conditions but also to the aspect ratio and form of the catalyst bed. The heat produced in the first phase must be effectively transferred to the endothermic and much-slower steam-reforming reaction, whereas in the final phase, heat must be lost to ensure that the thermodynamically limited water-gas shift reaction is favored.

Diesel exhaust-gas reforming for H2 addition to an aftertreatment unit

“…This was a key outcome from our earlier work [2,9,23] but also by more recent work on partial oxidation by Horn et al [24][25][26]. However, because these reactions occur consecutively at different stages of the catalyst bed, each providing new reactants and conditions downstream, the reaction rates of each reaction are affected differently by the monolith configuration (as well as the fuel type) [2]. Although the exothermic oxidation reactions generate heat close to the inlet face of the monolith, the onset of the endothermic H 2 -generating reactions (e.g.…”

“…The potential application of exhaust gas fuel reforming in internal combustion (IC) engines has been extensively studied, and the features that the reformer and catalyst design need to fulfil have been documented [1][2][3]. The technique involves reaction of fuel with engine exhaust gas (i.e.…”

“…The technique involves reaction of fuel with engine exhaust gas (i.e. O 2 , H 2 O and CO 2 ) in the presence of a catalyst to produce a gas that mainly contains H 2 , CO, H 2 O, CO 2 and N 2 .…”

“…aspect ratio) [2,9]. The latest studies have significantly advanced reforming technology for automotive applications.…”

Performance, combustion and emissions of a diesel engine operated with reformed EGR. Comparison of diesel and GTL fuelling

“…Although the authors have published a number of papers regarding engine operation with REGR mainly with standard diesel fuels [18][19][20], the different properties of GTL are expected to influence differently the partially premixed combustion patterns and the engine performance and emissions.…”