One major obstacle preventing widespread introduction of diesel engines is the lack of a suitable catalyst/reductant combination for this process. Hydrocarbons present in engine exhaust are generally less active and selective compared to ammonia. Although the NH3-SCR is very effective, the requirement of a separate NH3 source and injection system, combined with issues relating to NH3 slip, make this approach unappealing. Another effective reductant, urea, also has its shortcomings such as its high freezing point and the lack of urea distribution infrastructure. However, recent studies indicate that hydrogen is a promising reductant that achieves high NOx conversion over a wide temperature windowa. We are currently investigating a new strategy to achieve high NOx removal at low temperatures in an oxygen rich atmosphere. This approach involves a coupled system: an ethylene glycol (EG) reforming unit to convert a mixture of ethylene glycol and water into hydrogen and CO followed by a H2-deNO x unit. The group of Dumesic has found that aqueous phase reforming of ethylene glycol with high H2 selectivity can be achieved using a 3% Pt/Alumina or Raney Ni-Sn catalyst at 500Kb. Their experiments are conducted at higher pressures, near the bubble point of the solution, whereas our gas phase reforming is carried out near atmospheric pressure. Therefore, our low temperature reforming unit requires simple equipment that would be easy to operate. We have studied the performance of modified Pt supported catalyst for gas phase EG reforming at 230°C. Prior to testing, the samples were calcined in air followed by reduction in H2 at 250°C. Modification of the Pt supported catalysts with Na produce a twofold effect, an increase in the reforming activity and also stability of the catalyst. At a low EG concentration of 420 ppm, our results indicate complete conversion of ethylene glycol into hydrogen, mainly via decomposition. At higher EG concentrations (2.15% EG in the feed), oxidative reforming produced 1.4 H2/EG. We plan to couple this EG reforming unit to a de-NOx unit. Based on our calculations, 0.551 kg of reforming catalyst would be needed to deliver the amount of H 2 for complete NOx removala. Under realistic engine operating conditions, the amount of EG required for 100% NOx removal would be 1.81/hr, which suggests that such a coupled system would be feasible for practical application.
|Number of pages||1|
|Publication status||Published - Dec 1 2005|
|Event||05AIChE: 2005 AIChE Annual Meeting and Fall Showcase - Cincinnati, OH, United States|
Duration: Oct 30 2005 → Nov 4 2005
|Other||05AIChE: 2005 AIChE Annual Meeting and Fall Showcase|
|Period||10/30/05 → 11/4/05|
ASJC Scopus subject areas