Understanding NOx and Hydrocarbon Interactions for Cleaner Fuels

A recent paper titled "On the key kinetic interactions between NOx and unsaturated hydrocarbons: H-atom abstraction from C3-C7 alkynes and dienes by NO2" by Zhengyan Guo and colleagues explores the interactions between nitrogen oxides (NOx) and unsaturated hydrocarbons. The study emphasizes the significance of understanding these interactions for the transition to carbon-lean and carbon-free fuels, such as ammonia and hydrogen.

The authors conducted a comprehensive analysis of H atom abstraction by NO2 from C3 to C7 alkynes and dienes, resulting in the formation of three isomers of HNO2 (TRANS HONO, HNO2, and CIS HONO). The research involved high-level quantum chemistry computations to determine rate coefficients for 24 reactions across a temperature range of 298 to 2000 K, utilizing Transition State Theory and the Master Equation System Solver program.

Key findings include:

• The study identifies diverse branching ratios among different hydrocarbons and HNO2 isomers, highlighting both similarities and differences in their reactivity.
• Incorporating the calculated rate parameters into a recent chemistry model showed significant impacts on model performance, indicating a more reactive behavior for the studied alkynes and dienes in predicting autoignition characteristics.
• Sensitivity and flux analyses underscored the importance of H atom abstractions by NO2, suggesting a shift in fuel consumption dynamics towards these reactions compared to those involving hydroxyl radicals (OH).

The results call for further experimental investigations into the blending effects of NO2 on alkyne and diene chemistry, emphasizing the need for updated kinetic representations in future chemical models. This research contributes to a deeper understanding of combustion processes and the development of cleaner fuel technologies.

For further details, the paper can be accessed at arXiv:2408.17277.