Reduction of Nitrogen Oxides in Engine Exhaust Gases by the Addition of Cyanuric Acid

1989 ◽  
Vol 111 (3) ◽  
pp. 387-393 ◽  
Author(s):  
J. A. Caton ◽  
D. L. Siebers
Keyword(s):  
Nitric Oxide ◽  
Equivalence Ratio ◽  
Flow Reactor ◽  
Cyanuric Acid ◽  
Exhaust Gas ◽  
Oxide Reduction ◽  
Temperature Range ◽  
Nitric Oxide Concentration ◽  
Nitric Oxide Reduction ◽  
Reactor Temperature

Nitric oxide concentrations in a portion of the exhaust of a diesel engine operated with equivalence ratios between 0.25 and 0.75 were reduced by up to 98 percent by the addition of cyanuric acid. The cyanuric acid was combined with the exhaust gas in an electrically heated quartz flow reactor. The effects of the key process parameters (temperature, exhaust gas composition and residence time, and the overall engine equivalence ratio) on NO reduction by cyanuric acid were investigated. Nitric oxide reduction was evident at flow reactor temperatures above 700 K. The maximum nitric oxide reduction varied from 80 percent for a reactor temperature of 1180 K and an engine equivalence ratio of 0.25 to 98 percent for a temperature of 1120 K and an equivalence ratio of 0.75. The temperature range over which 60 percent or greater nitric oxide reduction was obtained was 1100 to 1340 K. Increasing the exhaust gas carbon monoxide concentration lowered the required reactor temperature and increased the temperature range for significant nitric oxide reduction. Increasing the exhaust gas nitric oxide concentration lowered the ratio of cyanuric acid to nitric oxide required for maximum nitric oxide reduction.

Reduction of Nitric Oxide in Diesel Exhaust With the Addition of Methylamine

1999 ◽  
Vol 121 (3) ◽  
pp. 563-568 ◽  
Author(s):  
Y. Nakanishi ◽  
Y. Yoshihara ◽  
K. Nishiwaki ◽  
T. Tanaka
Keyword(s):  
Nitric Oxide ◽  
Gas Phase ◽  
Diesel Exhaust ◽  
No Reduction ◽  
Nox Reduction ◽  
Molar Ratio ◽  
Exhaust Gas ◽  
Engine Exhaust ◽  
Temperature Range ◽  
Reactor Temperature

A Chemical gas-phase process capable to reduce the nitric oxide in diesel engine exhaust was studied. In this process, monomethylamine (CH3NH2) was added to the exhaust gas in a molar ration to NO varying between 1:1 and 4:1, Experiments were conducted in electrically heated quartz, reactors in a temperature range of 200°C to 600°C. Diesel exhaust gas and simulated exhaust gas were used in this experiment. The results showed thorough mixing of methylamine into the exhaust effectively breaks NO down into nitrogen and water, enabling more than 80 percent NO reduction in a reactor temperature range of 400°C to 540°C and at a molar ratio of 1. On the other hand, imperfect mixing between methylamine and exhaust gases results in excess ammonia and reduced NO decomposition. Consequently, it is suggested that the mixing is a very important factor in this technique. The results also show that the coexisting gases such as carbon monoxide, carbon dioxide, hydrocarbons, and water vapor in the diesel exhaust have no effect on NO reduction by methylamine. However, the presence of oxygen in excess of 10 percent in the exhaust is needed for an 80 percent NOx reduction. Furthermore, the mechanisms of the methylamine process were discussed.

scholarly journals Nitric Oxide Reduction of Heavy-Duty Diesel Exhaust Gas by NH3-SCR Upstream of the Turbocharger (Pre-Turbo SCR)

2014 ◽  
Vol 86 (9) ◽  
pp. 1611-1612 ◽  
Author(s):  
T. Rammelt ◽  
C. Hauck ◽  
J. Böhm ◽  
O. Deutschmann ◽  
R. Gläser
Keyword(s):  
Nitric Oxide ◽  
Diesel Exhaust ◽  
Exhaust Gas ◽  
Oxide Reduction ◽  
Heavy Duty ◽  
Nh3 Scr ◽  
Nitric Oxide Reduction ◽  
Heavy Duty Diesel

Ultra-Low Amounts of Palladium (0.005-0.05 Wt% Pd) Supported on Titania: Remarkable Low-Temperature Activity for NO Reduction with CO and Structure-Function Property Relationships in Methane Oxidation

2020 ◽  
Author(s):  
Konstantin Khivantsev ◽  
Libor Kovarik ◽  
Nicholas R. Jaegers ◽  
János Szanyi ◽  
Yong Wang
Keyword(s):  
Nitric Oxide ◽  
Carbon Monoxide ◽  
Methane Oxidation ◽  
Steam Reforming ◽  
Methane Steam Reforming ◽  
Oxide Reduction ◽  
Water Steam ◽  
Methane Steam ◽  
Anatase Titania ◽  
Nitric Oxide Reduction

<p>Atomically dispersed Pd +2 cations with ultra-dilute loading of palladium (0.005-0.05 wt%) were anchored on anatase titania and characterized with FTIR, microscopy and catalytic tests. CO infrared adsorption produces a sharp, narrow mono-carbonyl Pd(II)-CO band at ~2,130 cm<sup>-1</sup> indicating formation of highly uniform and stable Pd+2 ions on anatase titania. The 0.05 wt% Pd/TiO<sub>2</sub> sample was evaluated for methane combustion under dry and wet (industrially relevant) conditions in the presence and absence of carbon monoxide. Notably, we find the isolated palladium atoms respond dynamically upon oxygen concentration modulation (switching-on and switching off). When oxygen is removed from the wet methane stream, palladium ions are reduced to metallic state by methane and catalyze methane steam reforming instead of complete methane oxidation. Re-admission of oxygen restores Pd<sup>+2</sup> cations and switches off methane steam reforming activity. Moreover, 0.05 wt% Pd/TiO<sub>2</sub> is a competent CO oxidation catalyst in the presence of water steam with 90% CO conversion and TOF ~ 4,000 hr<sup>-1</sup> at 260 ⁰C. </p><p>More importantly, we find that diluting 0.05 wt% Pd/titania sample with titania to ultra-low 0.005 wt% palladium loading produces a remarkably active material for nitric oxide reduction with carbon monoxide under industrially relevant conditions with >90% conversion of nitric oxide at 180 ⁰C (~460 ppm NO and 150 L/g*hr flow rate in the presence of >2% water steam) and TOF ~6,000 hr<sup>-1</sup>. Pd thus outperforms state-of-the-art rhodium containing catalysts with (15-20 times higher rhodium loading; rhodium is ~ 3 times more expensive than palladium). Furthermore, palladium catalysts are more selective towards nitrogen and produce significantly less ammonia relative to the more traditional rhodium catalysts due to lower Pd amount nd lower water-gas-shift activity. Our study is the first example of utilizing ultra-low (0.05 wt% and less) noble metal (Pd) amounts to produce heterogeneous catalysts with extraordinary activity for nitric oxide reduction. This opens up a pathway to study other Pd, Pt and Rh containing materials with ultra-low loadings of expensive noble metals dispersed on titania or titania-coated oxides for industrially relevant nitric oxide abatement.</p>

A general strategy for designing metal-free catalysts for highly-efficient nitric oxide reduction to ammonia

Fuel ◽  
2021 ◽  
pp. 122442
Author(s):  
Qiang Zhou ◽  
Feng Gong ◽  
Yunlong Xie ◽  
Dawei Xia ◽  
Zhigang Hu ◽  
...  
Keyword(s):  
Nitric Oxide ◽  
General Strategy ◽  
Oxide Reduction ◽  
Metal Free ◽  
Highly Efficient ◽  
Nitric Oxide Reduction
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