Effect of loading sequence between Cu and Fe on SCR-C3H6 performance for Al-PILC based bimetallic catalysts

To investigate the effect of impregnation sequence on SCR-C3H6 performance, Al-PILC based catalysts with different impregnation sequences between Cu and Fe were prepared. Activity result showed that impregnation sequence influenced the SCR-C3H6 performance, where, the NO conversion followed the order from high to low: Cu-Fe/Al-PILC>FeCu/Al-PILC>CuFe/Al-PILC. XRD results indicated that the dispersion of the active phase was related to the impregnation sequence. The specific surface area was not the crucial factor affecting the activity. UV-Vis demonstrated that isolated Cu2+ and Fe3+ contributed to activity rather than CuO and Fe2O3 particles, and more isolated Cu2+ and Fe3+ existed on Cu-Fe/Al-PILC. H2-TPR and XPS results revealed that superior reduction ability and more surface adsorbed oxygen led to the excellent SCR-C3H6 performance for Cu-Fe/Al-PILC catalyst.

Simulation of Denitrification of Vehicle Exhaust over Cu-CHA Bazite Catalyst for a Monolith Reactor

A CFD model with chemical reaction kinetic and heat and mass transfer for a monolith reactor is established by COMSOL Multiphysics to investigate the influence of different operating conditions and water on denitrification efficiency for Cu‑CHA. At the low temperature range, water has little effect on the denitrification efficiency over the Cu‑CHA catalyst while NO conversion is increased by about 30% at the medium temperature. The concentration of O2 (CO2) has no significant effect on the performance of Cu‑CHA catalyst. The best ratio of NO2 to NOx in feed gases may be 1/2, which improves the denitrification efficiency and the yield of N2 but it produces relatively little N2O. The optimal ammonia‑nitrogen ratio is 1.1, where Cu‑CHA catalyst has fairly great denitrification efficiency and low NH3 leakage. Increasing inlet flow velocity and cross area of channels have negative effect on NO conversion, while longer channels and thicker substrate have the opposite effect.

Synergistic Effects of Bimetallic AuPd and La2O3 in the Catalytic Reduction of NO with CO

Bimetallic AuPd nanoparticles supported on TiO2 are known to catalyze the reduction of NO with CO. Here, we investigated the effects of the addition of lanthanum oxide to a AuPd/TiO2 catalyst with a AuPd particle size of 2.1–2.2 nm. The addition of La2O3 enhanced the catalytic activity; for example, at 250 °C, there was 40.9% NO conversion and 49.3% N2-selectivity for AuPd/TiO2, and 100% NO conversion and 100% N2-selectivity for AuPd-La (1:1)/TiO2. The temperature requiring 100% NO conversion dropped from 400 °C to 200 °C by the simple post-impregnation of La2O3 onto AuPd/TiO2. In situ diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS) combined with modulation excitation spectroscopy (MES) demonstrated that CO adsorption occurs first on Au atoms and then, within 80 s, moves onto Pd atoms. This transformation between two adsorption sites was facilitated by the addition of La2O3.

Dielectric Barrier Discharge Reactor for the Removal of NOx From Automotive Exhaust

In this study, a self-made wire-cylinder dielectric barrier discharge (DBD) reactor was used to remove NOx. The influence of electrical and gas parameters (e.g. structure, voltage, and frequency) and temperature on the NOx removal rate was studied systematically while operating the DBD reactor with a high-voltage positive–negative double pulse power supply. The experimental results showed that following conditions led to the optimal NO conversion rate and NOx removal rate: voltage of ±12 kV, pulse frequency up to 60 Hz, oxygen concentration at 6%, reaction temperature at 300°C, and C2H2:NOx ratio at 1.5. Under these conditions, the NO conversion rate and NOx removal rate reached the highest levels of 76.4% and 31.2%, respectively. Additionally, when the process was run in conjunction with a La0.7 Sr0.3 Ni0.5 Mn0.2 Fe0.3 O3 catalyst, the reactor efficiency increased markedly, and the NO conversion and NOx removal rates increased to 94.93% and 74.97%, respectively. The findings of this study demonstrate that DBD reactor technology shows promise for the removal of NOx from automotive waste streams.

Experimental demonstration of NO reduction and ammonia slip for diesel engine SCR system

This paper aims to investigate the characteristics of selective catalytic reduction(SCR) in a V2O5-WO3/TiO2 catalyst by studying the key parameter, and obtain the control method of NH3 injection under sample test bench. Four parameters are defined and adopted to represent the NO-NH3 reaction characteristics. The effect of NH3/NO ratio(NSR), catalyst temperature and NH3 injection period on NO conversion efficiency and NH3 slip was investigated. The correlation between NH3 slip and ammonia saturation storage level was studied. The experimental results show that the ammonia saturation storage level has great effects on NO reduction and NH3 slip. The NO conversion efficiency and NH3 slip strongly depends on the ammonia saturation storage level. Under such condition, the NO conversion efficiency is best when the ammonia saturation storage level is 68.2%~73%, until the value reach to 75% before the NH3 slip. Pulse injection can improve the NO conversion efficiency and NH3 slip. The period of pulse injection has few influence on the mean value of NO at the outlet, however, it affects the peak value of NO and NH3 slip. Using varied period pulse injection can further improve NO conversion efficiency and restrain NH3 slip. The outlet NO is able to be reduced by adopting suitable NH3 pulse injection interval.

No Catalytic Performance Analysis of Gasoline Engine Tapered Variable Cell Density Carrier Catalytic Converter

Improving the flow field uniformity of catalytic converter can promote the catalytic conversion of NO to NO2. Firstly, the physical and mathematical models of improved catalytic converter are established, and its accuracy is verified by experiments. Then, the NO catalytic performance of standard and improved catalytic converters is compared, and the influences of structural parameters on its performance are investigated. The results showed that: (1) The gas uniformity, pressure drop and NO conversion rate of the improved catalytic converter are increased by 0.0643, 6.78% and 7.0% respectively. (2) As the cell density combination is 700 cpsi/600 cpsi, NO conversion rate reaches the highest, 73.7%, and the gas uniformity is 0.9821. (3) When the tapered height is 20 mm, NO conversion rate reaches the highest, 72.4%, the gas uniformity is 0.9744. (4) When the high cell density radius is 20 mm, NO conversion rate reaches the highest, 72.1%, the gas uniformity is 0.9783. (5) When the tapered end face radius is 20 mm, NO conversion rate reaches the highest, 72.0%, the gas uniformity is 0.9784. The results will provide a very important reference value for improving NO catalytic and reducing vehicle emission.