Abstract
Nitrogen oxides are emitted in large quantities by vehicles, and solutions to the problem are sought after. Efforts towards abatement include Selective Catalytic Reduction, catalytic converters, and redesigning engines to make them more efficient. This article focuses on the photocatalytic oxidation, which involves the use of titanium dioxide and ultraviolet radiation to oxidise nitrogen oxides to nitrates. To test this, the interior of a serpentine reactor was coated with titanium dioxide and irradiated with various intensities of ultraviolet light, and the photocatalytic abatement was monitored for the exhaust fumes from a standalone 4-stroke test diesel engine. The conversion rates were calculated using the entering concentration and the concentration after a certain time increment. The rates varied between 13.7% and 37.3% and depended strongly on the relative humidity, as a higher relative humidity directly correlated with a better conversion. The irradiance was also varied, and a decline in the conversion rate occurred when the irradiance was increased.
Highlights
Nitrogen oxides—in this case referring to nitrogen oxide (NO), nitrogen dioxide (NO2), and nitrous oxide (N2O), collectively known as (NOx)—are a much-observed group of air pollutants and contributors to global warming
The interior of a serpentine reactor was coated with titanium dioxide and irradiated with various intensities of ultraviolet light, and the photocatalytic abatement was monitored for the exhaust fumes from a standalone 4-stroke test diesel engine
The conversion rate X was calculated after every time increment using Equation (1), and the progression shows a lower conversion rate for a lower relative humidity
Summary
Nitrogen oxides—in this case referring to nitrogen oxide (NO), nitrogen dioxide (NO2), and nitrous oxide (N2O), collectively known as (NOx)—are a much-observed group of air pollutants and contributors to global warming. A primary emitter of NOx are vehicles that involve the use of combustion engines. In particular, are regarded as a main source, despite their efficiency being higher than that of their petrol counterparts, due to their functioning under higher temperatures and pressures (compression ratios), which favours the production of thermal NOx. The European Union, in a legal effort to reduce NOx emissions, lower the limit of permissible levels with every stage (refer to Table 1), which gives manufacturers an incentive to design and build vehicles that comply with the most recent standard.
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