Measurement of automobile N₂O from bag and continuous stream by quantum cascade laser spectroscopy

Abstract

N 2 O emission from automobile has been regulated by the United States Environment Protection Agency due to its higher global warming potential compared to CO 2. Responding to this, an instrument for fast sensing of ultra-low concentration of N 2 O from automobile has become an urgent need. In this study, an instrument based on the quantum cascade laser spectroscopy has been developed and applied for certification testing of ultra-low N 2 O in automobile exhaust. The pulsed quantum cascade laser can emit coherent lights in the mid-infrared region where N 2 O shows strong absorption and better control of wavelength. Therefore, a very low detection limit can be achieved and interference of co-existing gases can be avoided using a super fine resolution of the mid-infrared spectrum. The US Code of Federal Regulations Parts 1065/1066 allows measuring N 2 O from sample storage bags, from a continuous dilute stream or a raw exhaust stream. Typically, batch (bag) sampling has better accuracy and repeatability, but continuous sampling is more efficient in terms of test cell running time and provides test-mode emissions. In this study, the quantum cascade laser analyzer has been applied to investigate correlations between bag sampling and continuous dilute exhaust sampling using a fleet of vehicles with a wide range of N 2 O emission levels all meeting United States Environment Protection Agency emission standards. Very good correlation between these two sampling methods was observed for the majority of tests conducted and in best case the difference was less than 61%. The direct injection gasoline vehicle emits higher N 2 O than conventional port injection gasoline vehicles. The quantum cascade laser analyzer has been successfully applied for United States Environment Protection Agency N 2 O certification test.

Preparation of Cu-BTC Supported Fly Ash-Based Catalyst and Research on Low-Temperature SCR Denitration Performance

“…The reason is that the three peaks are mainly the active component Cu -BTC peak, and in the catalytic reaction, the characteristic peak of the active component reacts with NH 3 or NO, causing the peak to weaken or even disappear. When SO 2 is introduced, compared with the infrared spectrum of Cu-BTC/FA after denitration, there are almost no new peaks, and the peak shapes are basically similar, which further proves that the sulfur resistance is good [31]. This can be well combined with XRD to explain its denitration mechanism.…”

Shear Stress on the Structure Control of a Supported Fly Ash‐Based Catalyst and Its Application in SCR* Denitration

“…Only Mn is loaded, the catalyst does not show the diffraction peak of manganese, indicating that the manganese oxide is evenly distributed on the surface of the catalyst, and the manganese mainly exists in the form of amorphous. The active 35] The rest of the diffraction peaks are obviously broadened, which indicates that Ce will reduce the degree of crystallization of the catalyst and promote the conversion of the active components in the catalyst from the crystalline phase to the amorphous phase, which is very beneficial to the catalytic reaction. MnÀ Ce/FA catalyst before and after reaction showed that the solid solution of MnÀ Ce structure disappeared, which indicated that the MnÀ Ce solid solution was the active substance of the catalyst mainly involved in the reaction.…”

Effect of N (N=Fe, Co, Ni, Cu, Ce) Loaded on Blast Furnace Slag in Low-temperature NH3-SCR

“…A large amount of slag is produced every year. Without proper treatment, the residual products occupy a large amount of high-quality land resources, which will not only cause environmental pollution, but also cause serious waste of resources (Rahman et al, 2019;Selvamani et al, 2017). However, because the current slag is mainly based on the preparation of cement or vitreous, it is a waste of resources for the slag to be rich in elements.…”