Advances in sustainable fuel technologies to meet international emission and efficiency standards has recently enhanced emphasis on rapid development and validation of novel fuels and fuel blendstocks. Presented here is a workflow developed to streamline the fuel design process, which consists of complementing existing experimental techniques with high throughput quantum calculations to create a holistic kinetic model valid across a wide range of temperatures and pressures. Microreactor experiments used in conjunction with photoionization mass spectrometry experiments are utilized to detect the major pyrolysis pathways and likely hydrogen abstraction sites. The experimental insight identifying important fuel radicals is used to complement electronic structure calculations to produce potential energy surfaces at the CCSD(T)/cc-pV∞Z//M06-2X/cc-pVTZ level of theory. These potential energy surfaces then become the foundation to generate pressure and temperature dependent rate constants which can be used to more accurately predict fuel properties of interest such as ignition delay time or sooting tendency. Two different classes of fuel blendstocks are examined to help demonstrate the widespread application and utility of our combined approach. First, straight chain alcohols (n-butanol and n-pentanol) are analyzed using this approach to explore the low temperature ignition chemistry resulting in an updated model which accurately predicts a variety of published rapid compression machine data. Second, the decomposition of methyl-terminated polyoxymethyl ethers (OME_n, CH₃O(CH₂O)_nCH₃where n = 1, 2, or 3) are examined to help explain recent observations of sooting tendency changes with respect to the chain length of the molecule. These distinct case studies help demonstrate the robustness and flexibility of the combined experimental and theoretical method created in streamlining chemical mechanism development and rapid fuel design for various targets and applications.

Nicole Labbe

Appearances