(85d) Modeling Green Diesel Hydroprocessing Via Molecule-Based Reactor

With the increasing demand to regulate carbon emission, the sustainable use of alternative feedstocks is a critical issue in next decades. Upgrading renewable oils via hydroprocessing is one promising technology. Triglycerides and their derivative fatty acids are the major molecular components of renewable oils. Green diesel is upgraded from renewable feedstocks by hydrodeoxygenation (HDO) and hydroisomerization (HI). Triglycerides and fatty acids are converted to a mixture of paraffinic molecules while limiting the production of CO2.

We developed a detailed HDO kinetic model of green diesel at the molecular level using the Aspen Molecule-Based (MB) reactor[1]. Starting from a list of triglycerides molecules, the detailed reaction paths of HDO were created and grouped to around 10 reaction families. As a result, more than 200 distinct reactions and around 100 molecules are included in that model. We applied a linear free energy relationship (LFER) to constrain the parameters of the model. Using one component of MB reactor: MB model builder, the HDO reaction network and kinetics were automatically converted to a dll that was loaded into the MB reactor unit op in Aspen HYSYS. Using the calibration function in MB reactor, we tuned the kinetic parameters of the HDO model based on literature data. The parity plots showed good agreement between the predicted results and experimental data.

We used Aspen MB hydrotreater to model the hydroisomerization of the effluent from MB HDO. By leveraging selected separation unit ops in HYSYS such as flash, column, etc., a waste cooking oil hydroprocessing case was created in Aspen HYSYS. The representative results of the case will be discussed.

Therefore, MB reactor in Aspen HYSYS gives users the opportunity to simulate and optimize the sustainable use of renewable feedstocks.

[1] Hou and Campbell “Molecule-Based EQUATION ORIENTED Reactor Simulation Infrastructure And Its Model Reduction”,Docket No.: 1086.2062-000