The effects of regeneration-phase CO and/or H2 amount on the performance of a NOX storage/reduction catalyst

The effects of regeneration-phase CO and/or H₂, and their amounts as a function of temperature on the trapping and reduction of NO_X over a model and a commercial NO_X storage/reduction catalyst have been evaluated. Overall, for both catalysts, their NO_X removal performance improved with each incremental increase in H₂ concentration. For the commercial sample, using CO at 200 °C, beyond a small amount added, was found to decrease performance. The addition of H₂ to the CO-containing mixtures resulted in improved performance at 200 °C, but the presence of the CO still resulted in decreased performance in comparison to activity when just H₂ was used. With the model sample, the presence of CO resulted in very poor performance at 200 °C, even with H₂. The data suggest that CO poisons Pt sites, including Pt-catalyzed nitrate decomposition. At 300 °C, H₂, CO, and mixtures of the two were comparable for trapping and reduction of NO_X, although with the model sample H₂ did prove consistently better. With the commercial sample, H₂ and CO were again comparable at 500 °C, but mixtures of the two led to slightly improved performance, while yet again H₂ and H₂-containing mixtures proved better than CO when testing the model sample. NH₃ formation was observed under most test conditions used. At 200 °C, NH₃ formation increased with each increase in H₂, while at 500 °C, the amount of NH₃ formed when using the mixtures was higher than that when using either H₂ or CO. This coincides with the improved performance observed with the mixtures when testing the commercial.     

Physiological and molecular study on the anti-obesity effects of pineapple (Ananas comosus) juice in male Wistar rat

Food Science and Biotechnology - The present study was performed to assess anti-obesity effects of raw pineapple juice in high fat diet (HFD)-induced fatness. Based on food type, rats were divided...     

Investigating the Effect of NO Versus NO2 on the Performance of a Model NO X Storage/Reduction Catalyst

The effects of using NO or NO₂ as the NO _X source on the performance of a NO _X storage/reduction catalyst were investigated from 200 to 500 °C. The evaluation included comparison with constant cycling times and trapping the same amount of NO _X during the lean phase. With NO₂ as the NO _X source, better trapping and reduction performance was attained in comparison to NO, at all operating temperatures except 300 °C. This exception, under the conditions tested, was likely due to high NO oxidation activity and rapid trapping of NO₂, although it is expected that extending the trapping time would lead to consistent differences. Several reasons for the observed improvements at 200, 400 and 500 °C with NO₂ relative to NO are discussed. One that can explain the data, for both trapping and release improvement, is treating the monolith as an integral reactor. With NO₂, more NO _X is trapped at the very inlet of the catalyst, whereas with NO, the maximum in trapping during cycling occurs slightly downstream. Thus more of the catalyst can be used for trapping with NO₂ as the NO _X source. The decreased release during catalyst regeneration is similarly explained; with more being released at the very inlet, there is more residence time and therefore contact with downstream Pt sites, but more importantly more interaction between reductant and stored NO _X . NH₃ and N₂O measurements support this conclusion.