Strategic binary initiators for enhanced thermal cracking of hydrocarbons

Initiators are known to enhance hydrocarbon cracking conversion, and the development of high-performance initiators has long been a persistent goal. In this work, a binary initiator system comprising 1-nitropropane (1-NP) and triethylamine (TEA) was strategically designed to enable efficient utilization of active free radicals during initiation cracking. The results show that at 575 °C and 600 °C, the addition of 4 wt% of the binary initiator (with a mass ratio of 1-NP to TEA of 1:1) increases the cracking conversion of n- hexane by 5.01 wt% and 5.53 wt%, respectively, outperforming the combined effect of using either initiator alone at the corresponding dosages. Analysis of key intermediates from binary initiator cracking, combined with DFT calculations, reveals mutual interaction between the active free radicals generated by decomposition of 1-NP and TEA. The relatively higher activity of 1-NP promotes premature decomposition of TEA, thereby fully leveraging the cracking performance of TEA. In contrast, the relatively lower activity of TEA enables it to capture excess free radicals from 1-NP decomposition, significantly improving the utilization efficiency of the active radicals generated by 1-NP. As a result, the binary initiator system exhibits an intermolecular synergistic initiation effect during the cracking process. These findings contribute to a better understanding of the initiation mechanism and guide the design and screening of effective initiators for hydrocarbon cracking.