Deutschmann, O.

Maier, L.

Tischer, S.

Woo, M.

Wörner, M.

English

Wörner, Martin

KITopen

KIT – The Research University in the Helmholtz Association Reaction mechanism• 3 bulk species, 10 surface species• Reaction path from nitrobenzene to aniline for T>400 K (mechanism B [3])*M. Woo1, M. Wörner1, L. Maier1, S. Tischer1, O. Deutschmann1,21Institute of Catalysis Research and Technology (IKFT)2Institute for Chemical Technology and Polymer Chemistry (ITCP)A Numerical Study on Gas-Liquid Taylor Flow for Catalytic Hydrogenation of Nitrobenzene with Detailed Kinetic Mechanism Simulation of the heterogeneously catalyzed hydrogenation of nitrobenzene to aniline for Taylor flow in a monolith reactor Methodology• Coupling two computer codes: TURBIT-VOF [1] for the gas-liquid flow and DETCHEMTM [2] for the reaction kinetics at the wall• Moving reference frame approach for mass transfer simulations• Detailed reaction mechanism based on density functional theory Development of computer code for gas-liquid Taylor flow with surface reaction has been accomplished by coupling TURBIT-VOF/DETCHEMTM Moving reference frame approach allows saving computational time supposed the feedback of mass transfer on hydrodynamics is negligible Using a detailed reaction mechanism, a qualitative analysis on the coupling between bulk and surface species has been accomplishedAcknowledgementWe gratefully acknowledge the funding of this project by Helmholtz Energy Alliance “Energy Efficient Chemical Multiphase Processes“ (HA-E-0004) and thank the Steinbeis GmbH for a cost-free license of DETCHEMTMObjectivesReferences [1] A. Onea et al., Chem. Eng. Sci. 64 (2009) 1416-1435[2] O. Deutschmann et al., DETCHEMTM User Manual, 2012, http://www.detchem.com[3] L. Zhang et al., RSC. Adv. 5 (2015) 34319 Test conditions• Temperature T = 323 K, pressure p = 7 bar, channel height h = 100 μm• Reynolds number Re=ρLhUB/μL=120, capillary number Ca =UBμL/σ=0.044Periodic conditionCatalyzed wallCatalyzed wallFlow driven by pressure dropHydrogenNitrobenzenePeriodic condition+ + (Hydrogenation of nitrobenzene)• Hydrogen mass transfer is largest at the rear part of the bubble where the thickness of the liquid film is thinnest• Aniline is mainly produced in the rear part of the liq. film as well• An axial variation of surface species appears at the beginning of the mass transfer simulations and then gradually diminishes• Hydrogen is transferred from the bubble while H2O and aniline are produced by reaction as well as change of surface species Temporal distributions of bulk and surface speciesReactive mass transfer with a Taylor flow Time evolution of bulk and surface speciesContact: M. Woo (mino.woo@kit.edu), M. Wörner (martin.woerner@kit.edu),Institute of Catalysis Research and Technology, Engesserstr. 20, 76131 Karlsruhe, Germany Jahrestreffen ProcessNet-Fachgruppe Mehrphasenströmungen14.-15. März 2017DresdenNumerical approachesConclusions Hydrodynamics• Two-dimensional incompressible Navier-Stokes equation with Volume-of-fluid (VOF) method • Isothermal simulation, no phase change• Constant physical properties• Simulation in fixed frame of reference till quasi-steady statex*Sitefraction[-]0.5 1 1.5 2 2.5 300.10.20.30.40.50.60.70.8(Pd)H2O(Pd)H(Pd)NB(Pd)NBH(Pd)NBH2(Pd)PHG(Pd)PHA(Pd)PHNH(Pd)AN(Pd)x*Sitefraction[-]0.5 1 1.5 2 2.5 300.10.20.30.40.50.60.70.8(Pd)H2O(Pd)H(Pd)NB(Pd)NBH(Pd)NBH2(Pd)PHG(Pd)PHA(Pd)PHNH(Pd)AN(Pd)Time = 2.5 ms Time = 5 msMoving frameFixed frameQuasi-steady state velocity field of the Taylor flow in fixed (bottom half) and moving (upper half) frame of reference* Reaction rate at 1500 K is utilized for qualitative analysis, NB(Pd), AN(Pd)NBH(Pd)NBH2(Pd)PHG(Pd)PHA(Pd)PHNH(Pd)P 1.14x*Sitefraction[-]0.5 1 1.5 2 2.5 300.10.20.30.40.50.60.70.8(Pd)H2O(Pd)H(Pd)NB(Pd)NBH(Pd)NBH2(Pd)PHG(Pd)PHA(Pd)PHNH(Pd)AN(Pd)Time = 0.25 ms(Upper half) (Lower half)Evaluate wall concentrationsby linear extrapolation*m, ; walli kc Calculate reaction ratesi ik k ik is k c Update reactive fluxes at the boundary3(mol/m )ic2(mol/m s)is *; walli ks TURBIT-VOF DETCHEMTMNon-dimensional Dimensional*ref/c c c * ref ref/s s u c  Coupling of the two codes Mass transfer in moving reference frame• Concentration equations are solved with frozen velocity field from hydrodynamic simulation• One way coupling, no homogeneous reactionTime stepnn+1c*H2 c*AN

A Numerical Study on Gas-Liquid Taylor Flow for Catalytic Hydrogenation of Nitrobenzene with Detailed Kinetic Mechanism

https://publikationen.bibliothek.kit.edu/1000068709/5319451

A Numerical Study on Gas-Liquid Taylor Flow for Catalytic Hydrogenation of Nitrobenzene with Detailed Kinetic Mechanism

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