A Study Of The Molecular Simulation On The Pyrolysis Reaction Of Small Alkanes

Because of the rapid development of ethylene industry makes cracking raw materials to relative shortage,the composition has become more complicated,and the complexity of hydrocarbon cracking reaction,aggravating the difficulty of hydrocarbons kinetic further.Although it has had empirical model,mechanism model,molecular model and lumped model at present,each model has its own limitations,can’t overall describe the detail laws of hydrocarbon molecular at cracking process.In order to adapt to the trend of raw materials instability that it is caused by the shortage of current raw materials,a general dynamics model with some extrapolation,and can accurately predict the distribution of product,providing the basis for the optimization of raw materials must be established,it can simulate the laws of cracking raw materials with less time,manpower,and to simplify the evaluation method of feed stocks depending on many experiments only.Over the years,with the ongoing development of the computer numerical simulation technology,it has the ability to guide the practice in theory,yet the molecular simulation is a compelling research method.In this thesis,the molecular simulation technique is introduced into the study of steam cracking reaction,and a new method that studies hydrocarbon cracking reaction is proposed,this method is going to free radicals reaction mechanism,the existing laws and experimental dates combined.Firstly,"molecular simulation experiments" are done to hydrocarbon molecules in computer,the cracking reaction and reaction path are understood from the micro perspective,this paper deals with the Dmol3 module of Materials studio software,using ethane,propane or n-butane as materials,the dynamics parameters of cracking on them—the activation energies are simulated;secondly,in order to verify the simulated results to be accurate,by comparing and analyzing the simulation results with existing experimental data,the result shows the accuracy of the simulation is higher,and compared to reliable experimental dates,most of the relative error within 10%;Lastly,in order to further prove the analogy method to be accurate,reaction path and free radicals reaction mechanism were studied,it turned out:free radicals mechanism is obtained by the molecular simulation is most consistent with existing pyrolysis and the findings come from experimental research,meanwhile the results of the simulation are basis of judging the accuracy of the experiment and existing laws.can we see that the method of the molecular simulation,existing pyrolysis is consistent with one combined with the results of the experiment.