[Che-student-staff-list] Seminar Announcement - Dow Chemical April 25th

[Mamph, Jennifer A]

School of Chemical Engineering
James Ringer, Dan Hickman, Eric Stangland
Dow Chemical

"Catalyst Development and Reactor Scale-up for Fluidized Bed Conversion of Ethane to Vinyl Chloride"
April 25, 2013
3:30 - 5:00 p.m.
FRNY 3059
Technical Seminar Abstract:
Novel LaOCl/LaCl3 catalysts have been discovered that enable the production of vinyl chloride monomer from ethane.  This ethane-based process results in both capital savings and raw materials savings when compared to the current most effective vinyl technology.  These materials are unique in the world of chlorination/oxychlorination as the mechanism for chlorination over LaOCl/LaCl3 occurs on a catalyst without a redox metal center, unlike the conventional CuCl2 catalysts used for oxychlorination, where the Cu species are reducible.  Catalyst characterization using unsteady-state reactivity studies, Raman, XPS, and EXAFS demonstrate that LaOCl/LaCl3 catalysts have complex and rich surface compositions that are not represented by their bulk stoichiometry. Even after extensive activation in HCl or Cl2, the catalyst surface contains a variety of chlorine, oxide, and hydroxide species.    Hydrocarbon chlorination occurs through lattice chlorine, as only gas-phase oxygen, and therefore oxygen reduction on the time-scale of chlorination, is necessary for activity.  The presence of gas-phase HCl or Cl2 is not required but serves to rechlorinate the catalyst surface, completing the catalytic cycle.  Density functional theory calculations are consistent with this plausible mechanism directly related to reactivity of surface chlorine species and not gas-phase chlorine free-radicals.  Selectivities and activities for various chlorinated hydrocarbons and COx change with surface chlorination levels, with the highest chlorination rates and selectivities observed on fully-chlorided catalysts.  The work to date shows that maintaining the catalyst surface in an optimal state of chlorination appears vital to achieve high rates and selectivities.  In addition to reviewing the catalytic features of this system, this presentation will review the engineering approaches taken and the challenges encountered in the scale-up of a fluidized bed reactor based on this catalyst technology.  This presentation will highlight the application of chemical reaction engineering and catalysis principles to a real industrial reactor scale-up, with special attention given to the unexpected and atypical challenges encountered in this development effort.

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