Promotion effect of hydrogen addition in selective catalytic reduction of nitrogen oxide emissions from diesel engines fuelled with diesel-biodiesel-ethanol blends

Ethanol and palm oil biodiesel blended with diesel fuel have the potential to reduce greenhouse gas emissions, such as carbon dioxide (CO2), and can gradually decrease dependence on fossil fuels. However, the combustion products from these fuels, such as oxides of nitrogen (NOx), total hydrocarbons (THC) and particulate matter (PM), require to be examined and any beneficial or detrimental effect to the environment needs to be assessed. This study investigates the hydrocarbon selective catalyst reduction (HC-SCR) activities by the effect of combustion using renewable fuels (biodiesel-ethanol-diesel) blends and the effect of hydrogen addition to the catalyst, with the various diesel engine operating conditions. Lower values rate of heat released were recorded as the ethanol fraction increases, resulting in trade-off where, lower NOx was produced while greater concentration of carbon monoxide (CO) and THC was measured in the exhaust. Consequently, increasing the THC/NOx promoting the NOx reduction activity (up to 43%). Additionally, the HC-SCR performance was greatly heightened when hydrogen was added into the catalyst and able to improve the NOx reduction activity up to 73%. The experiment demonstrated plausible alternatives to improve the HC-SCR performance through the aids from fuel blends and hydrogen addition. (C) 2021 THE AUTHORS. Published by Elsevier BV on behalf of Faculty of Engineering, Alexandria University.

Automated summary

The study examines the combustion effects of ethanol and palm oil biodiesel blends with diesel, as well as the impact of hydrogen on catalyst performance. Results show that increasing ethanol content can reduce NOx emissions but lead to higher CO and THC concentrations, while the addition of hydrogen significantly enhances NOx reduction activity.