Kinetic Modeling of 1,2-Dichloropropane (PDC) Free-Radical Chlorination Hangyao Wang The Dow Chemical Company, Olefins, Aromatics and Alternatives R&D, Building 251, 2301 N. Brazosport Blvd., Freeport, TX 77541 Max Tirtowidjojo Olin Blue Cube Operations, LLC, 4239 East Hwy 332, OC-1120/260, Freeport, TX 77541 Christina Zarth The Dow Chemical Company, Mathematical Modeling, Hagebuttenweg 30, D-27404 Zeven, Germany David Laitar The Dow Chemical Company, Corporate R&D, 1776 Building, Midland, MI 48674 DOI 10.1002/aic.15163 Published online February 10, 2016 in Wiley Online Library (wileyonlinelibrary.com) Recent government mandates have lowered the permissible global warming potential (GWP) for refrigerants in mobile air conditioning substantially below that of the hydrofluorocarbon products that are used currently. Potential replace- ments, hydrofluoro-olefins (HFO), have a reduced impact on the ozone layer and lower GWP. Many desirable HFO compounds, such as HFO-1234yf, can be produced utilizing chlorocarbons as feedstocks such as the preferred 1,1,2,3- tetrachloropropene (TCPE). TCPE can be produced by several routes; however, producing TCPE from 1,2-dichloropro- pane (PDC) is potentially more desirable environmentally and economically since PDC is a byproduct of propylene oxide and allyl chloride production. One process option is to convert PDC to pentachloropropane (PCP) intermediates by chlorination, followed by dehydrochlorination of the PCPs to produce TCPE. In this work, we show that PCPs can be produced through the chlorination of PDC in a free-radical liquid phase reaction and have developed a kinetic model for PDC chlorination based on the relevant free radical elementary reactions. Thermodynamic properties includ- ing standard heats of formation, standard entropies of formation, and heat capacities for the radical and non-radical species were estimated by using ab initio and COSMOtherm calculations and validated against available experimental data. The reaction equilibrium constants were determined from the Gibb’s free energies of the reactants and products. Phase equilibria were calculated by means of a consistent set of thermodynamic properties of the species. In addition, physical properties such as the vapor pressure of pure components involved in the reaction network were also esti- mated. Ab initio transition state calculations were employed to estimate the rate parameters including pre-exponential factors and activation energies for the relevant reactions. The activation energies of some key reactions were then adjusted to match experimental data. The resulting kinetic model provided a basis for process yield optimization and scale up. VC 2016 American Institute of Chemical Engineers AIChE J, 62: 1174–1191, 2016 Keywords: simulation, molecular, thermodynamics/statistical, reaction kinetics, computational chemistry (kinetics/ thermo) Introduction Hydrofluorocarbon (HFC) products are utilized widely in many applications including refrigeration, air conditioning, and as propellants and foam expansion agents. Even though HFCs have proven to be more climate friendly than the chlorofluoro- carbon and hydrochlorofluorocarbon products that they replaced, further restrictions on the global warming potential (GWP) for refrigerants used in mobile air conditioning applica- tions have necessitated identification of even more environmen- tally benign materials with 100 year GWPs of less than 150. 1 Hydrofluoro-olefins (HFO) are one such class of materials that have reduced detrimental impact on the ozone layer and generally lower GWP in addition to low flammability and tox- icity. 4 HFO-1234yf (2,3,3,3-tetrafluoroprop-1-ene), a fourth generation refrigerant, has a 100 year GWP of 4 and is used in mobile A/C systems. 2,3 It has been “phased in” per Europe F- gas regulations started in 2012, and it will be required in all new vehicles in Europe starting in 2017. Widespread use in This contribution was identified by Professor Richard West (Northeastern Uni- versity) as the Best Presentation in the session “Liquid Phase Reaction Engineer- ing” of the 2014 AIChE Annual Meeting in Atlanta, GA. Correspondence concerning this article should be addressed to H. Wang at hwang@dow.com. VC 2016 American Institute of Chemical Engineers 1174 AIChE Journal April 2016 Vol. 62, No. 4