Temperature and pressure dependence of n-hexadecane cracking

Ultrapyrolysis of n-hexadecane in a novel micro-reactor

Pyrolysis experiments on n-hexadecane (n-C16) were conducted at 673–723 K and n-C16 concentrations of 0.07–1.47 mol/L by using batch type reactors. The main products of n-C16 pyrolysis were n-alkanes and 1-alkenes at all the reaction conditions. The 1-alkene/n-alkane ratio decreased with increasing n-C16 concentration at all the reaction temperatures. The rate of n-C16 pyrolysis increased to a maximum and then decreased with increasing n-C16 concentration. The activation energy of the overall rate constant of n-C16 pyrolysis was 196 kJ/mol at 0.07 mol/L of n-C16 concentration and 263 kJ/mol at 0.22 mol/L. To describe these phenomena, a mathematical model for the pyrolysis that expresses the radical network reaction, including initiation, isomerization, β-scission, H abstraction, and termination, was developed. The effect of radical size on the rates of bimolecular reactions (H abstraction and termination) was important for a correct quantitative description. Comparison between the experimental data and the model showed that the rates of bimolecular reactions were inversely proportional to the carbon number i of radical Ri. The model can predict product distribution and n-C16 pyrolysis rate in a wide range of temperatures (603–893 K) and n-C16 concentrations (6.86 × 10−3 2.48 mol/L). Furthermore, the model can describe the pyrolysis kinetics of n-C10–n-C25 by considering the carbon number of the hydrocarbon.

Kinetics and product distribution of n-hexadecane pyrolysis

The pyrolysis of the long (C≥5) chain n-alkanes is reviewed with emphasis on the radical chain mechanism and on the reactions of the intermediate alkyl radicals. The effects of the experimental conditions and conversion on the types and distributions of the final products are also evaluated. The Arrhenius rate parameters are summarized for both the elementary steps and the overall decomposition reactions.

The thermal decomposition of hydro-carbons. Part 1. n -alkanes (C≥5)

As important products of heavy oil pyrolysis, heavier components such as gasoline and diesel supply the vast majority of energy demand through combustion, and lighter components such as ethylene and propylene are the main sources of industrial chemicals and plastic products. In this work, pyrolysis of hexadecane, as the model compound, was studied by reactive force field (ReaxFF) molecular simulation at high temperatures and high pressures. It was confirmed by unimolecular simulations that there exist eight different initial mechanisms all starting with C–C bond dissociation. The biradical mechanism was verified, through which the pyrolysis process can be accomplished within a shorter time. The enthalpy of reaction was calculated by the QM method, which was well consistent with ReaxFF calculation results. Multimolecular simulations showed that there is a strong dependency relationship between products distribution and temperature, as well as that between reaction rates and temperature. The optimal conditi...

Herbert Groenendyk

Papers

Controlled Thermolytic Dissociation of Hexadecane and Methyl Decanoate

Identification of Functional Groups by Controlled Thermolytic Dissociation