Detailed experimental and kinetic modeling study of 3‐carene pyrolysis

Abstract

3-Carene is an important potential biofuel with properties similar to the jetpropellant JP-10. Its thermal decomposition and combustion behavior is to date unknown, which is essential to assess its quality as a fuel. A combined experimental and kinetic modeling study has been conducted to understand the initial decomposition of 3-carene. The pyrolysis of 3-carene was investigated in a jet-stirred quartz reactor at atmospheric pressure, at temperatures varying from 650 to 1050 K, covering the complete conversion range. The decomposition of 3carene was observed to start around 800 K, and it is almost complete at 970 K. Online gas chromatography shows that primarily aromatics are generated which suggests that 3-carene is not a good fuel candidate. The potential energy surface for the initial decomposition pathways determined by KinBot shows that a hydrogen elimination reaction dominates, giving primarily cara-2,4-diene. Next to this molecular pathway, radical pathways lead to aromatics via ring opening. The kinetic model was automatically generated with Genesys and consists of 2565 species and 9331 reactions. New quantum chemical calculations at the CBS-QB3 level of theory were needed to calculate rate coefficients and thermodynamic properties relevant for the primary decomposition of 3-carene. Both the conversion of 3-carene and the yields of the primary products (ie, benzene and hydrogen gas) are well predicted with this kinetic model. Rate of production analyses shows that the dominant pathways to convert 3-carene are hydrogen elimination reaction and radical chemistry.

Automated Reaction Kinetics of Gas-Phase Organic Species over Multiwell Potential Energy Surfaces

“…KinBot has been used by Zhang et al 64 to study the hightemperature unimolecular decomposition pathways of 3-carene and to understand the initial steps of its pyrolysis. Beyond the expected unimolecular pathways, KinBot suggested a direct molecular hydrogen-elimination reaction.…”

“…KinBot , is a workflow code that drives a series of quantum-chemical calculations with the aim to go from structure to rate coefficients. It has been applied to a wide range of gas-phase chemical kinetics problems by us ,− and others. − KinBot targets reactions of organic species in the gas phase. A detailed description of the code is provided in ref ; therefore, here we present a relatively brief overview.…”

Catalytic Fast Pyrolysis of JP-10 and 3-Carene Using Analytical Py-GC/MS for the Production of Low Molecular Weight Hydrocarbons

“…Arunan and co-workers , observed that the product distribution from the supercritical pyrolysis of 3-carene (8–14 bar, 650–950 °C) is primarily composed of light linear hydrocarbons such as acetylene, allene, and butadiene, along with minor products like toluene, benzene, and cyclopentadiene. In contrast, Zhang et al reported that the major products obtained from 3-carene pyrolysis were primarily cyclic compounds in the temperature range of 480–675 °C, with the abundance of cymene at low temperatures. Toluene dominated the products in a wide temperature range (540–780 °C), while xylene’s and benzene’s productions increased with temperature.…”

“…In spite of its potential fuel properties, 3-carene has received low research interest as a potential jet fuel. Sharath et al and Zhang et al are among the researchers who explored 3-carene as a prospective fuel. Arunan and co-workers , observed that the product distribution from the supercritical pyrolysis of 3-carene (8–14 bar, 650–950 °C) is primarily composed of light linear hydrocarbons such as acetylene, allene, and butadiene, along with minor products like toluene, benzene, and cyclopentadiene.…”