Experimental study on low-pressure and high-temperature pyrolysis of 1, 3-butadiene using synchrotron radiation and SiC flash microreactor

Abstract

1,3-Butadiene is a crucial intermediate in hydrocarbon combustion and pyrolysis processes and plays a significant role as a precursor in the formation of polycyclic aromatic hydrocarbons (PAHs) and soot. This study investigates the low-pressure and high-temperature pyrolysis of 1,3-butadiene by using a newly designed silicon carbide (SiC) tubular flow microreactor, in combination with supersonic molecular beam sampling, synchrotron radiation vacuum ultraviolet single-photon ionization, and reflective time-of-flight mass spectrometry (SR-VUV-TOF-PIMS). We identified 36 pyrolysis products, ranging in mass-to-charge ratio (m/z) from 15 to 128, which included free radicals and isomeric species. The study determined the initial pyrolysis temperature of the parent compound and the initial formation temperatures of the products. Comparative analysis of our results with previous literature revealed the primary cleavage pathways in this work: 1,3-C₄H₆ → C₂H₄ + C₂H₂, 1,3-C₄H₆ → 1,2-C₄H₆, 1,2-C₄H₆ → C₃H₃· + CH₃·_, 1,3-C₄H₆ + C₃H₃· → C₃H₄ + C₄H₅·, 1,3-i-C₄H₅· → C₄H₄ + H· and 1,3-n-C₄H₅· → C₄H₄ + H·. These studies contribute valuable insights into the mechanisms of hydrocarbon combustion and pyrolysis, as well as the reference for the formation processes of PAHs and soot.