Kinetic modeling of NH3-SCR over a supported Cu zeolite catalyst using axial species distribution measurements

In this study, a kinetic model is developed for NH3-SCR over a honeycomb-monolith-supported Cu-zeolites using intra-catalyst axial species distribution measurements. An ammonia TPD experiment, together with micro calorimetry data were used for tuning the ammonia adsorption and desorption properties. The spatial distribution for NO oxidation, NH3 oxidation and NH3 "Standard" SCR were modeled between 200 and 400 degrees C. Four-step protocol measurements were employed in order to validate the transient functions of the model. The resulting kinetic model provides good spatiotemporal simulation of the SCR reaction and component reactions throughout the monolith catalyst system

Community paramedicine in Central Oregon: A promising model to reduce non‐urgent emergency department utilization among medically complex Medicaid beneficiaries

Abstract Background Community paramedicine has emerged as a promising model to redirect persons with nonmedically emergent conditions to more appropriate and less expensive community‐based health care settings. Outreach through community paramedicine to patients with a history of high hospital emergency department (ED) use and chronic health conditions has been found to reduce ED use. This study examined the effect of community paramedicine implemented in 2 rural counties in reducing nonemergent ED use among a sample of Medicaid beneficiaries with complex medical conditions and a history of high ED utilization. Methods A cluster randomized trial approach with a stepped wedge design was used to test the effect of the community paramedicine intervention. ED utilization for non‐urgent care was measured by emergency medicine ED visits and avoidable ED visits. Results The community paramedicine intervention reduced ED utilization among a sample of 102 medically complex Medicaid beneficiaries with a history of high ED utilization. In the unadjusted models, emergency medical ED visits decreased by 13.9% (incidence rate ratio [IRR], 0.86; 95% confidence interval [CI], 0.76–0.98) or 6.1 visits saved for every 100 people. Avoidable emergency department visits decreased by 38.9% (IRR, 0.61; 95% CI, 0.44–0.84) or 2.3 visits saved for every 100 people. Conclusion Our results suggest community paramedicine is a promising model to achieve a reduction in ED utilization among medically complex patients by managing complex health conditions in a home‐based setting

Experimental evidence of the mechanism behind NH3 overconsumption during SCR over Fe-zeolites

Isotope labeled (NO)-N-15 was used to investigate the mechanism of the unusual overconsumption of NH3 during standard SCR over Fe-zeolite, under conditions during which NH3 oxidation with O-2 alone (without NO) was unfavorable. When the Fe-BEA catalyst was exposed to the (NO)-N-15 + (NH3)-N-14 + O-2 gas mixture at 250 and 300 degrees C, the resulting products included (NO)-N-14, a product of (NH3)-N-14 oxidation under SCR conditions. However, (NO)-N-14 was not detected when Fe-BEA was exposed to (NH3)-N-14 + O-2. Since the only source of N-14 derives from (NH3)-N-14, with the labeled gas mixture used, the (NO)-N-14 during SCR must have originated from oxidation of (NH3)-N-14. Furthermore, twice as much (NN)-N-14-N-14 was observed at 300 degrees C under SCR conditions in comparison with NH3 oxidation using O-2 alone. Under SCR conditions, the (NO)-N-14 formed through the unusual oxidation route further reacted with (NH3)-N-14 to produce N-14(2). Thus, for the first time, we have experimental evidence for the unusual overconsumption of ammonia during SCR over Fe-zeolites

The influence of the preparation procedure on the storage ande regeneration behavior of Pt and Ba based NOx storage and reduction catalysts

The influence of the preparation procedure on the performance of NOx storage and reduction catalysts was investigated by means of flow reactor experiments. Three catalysts were examined; one Pt/Al and two Pt/Ba/Al samples. One of the Pt/Ba/Al samples was prepared with Pt impregnated on Al/Ba and one with Ba impregnated on Al/Pt. The results clearly show that the preparation procedure influences the behavior of NOx storage and reduction catalysts both during lean and rich conditions. The order of the impregnation steps is crucial especially at higher temperatures; a higher storage capacity is obtained when impregnating Al/Pt with Ba than when impregnating Al/Ba with Pt. The storage increased with as much as 54% when adding Ba in the last step. The N2O and NH3 formation is also affected by the preparation procedure; there is a clear dependency on the order of impregnation steps. Moreover, N2O is not only formed during rich conditions but also in the beginning of the lean period over the Pt/Al and Al/Pt/Ba samples