Reporter: Sun Rui Supervisor: Xin Feng 2013-7-10

Modeling of reaction in monolithic catalyst with triangular channels for cyclohexanone ammoximation Reporter: Sun Rui Supervisor: Xin Feng 2013-7-10

Outline • Introduction • Modeling • 2.1 General Model Assumption • 2.2 Liquid-Liquid-solid Three-Phase Flow Patterns in the channel • 2.3 Mass transfer in monolithic catalyst with triangular channels • 3.Next plan Tianjin University

1. Introduction Fig.1 Set-up for continuous cyclohexanone ammoximation reaction on monolithic TS-1/cordierite catalyst Tianjin University

1. Introduction Table.1 Datas of the cordierite Cross-section Sigle channel Monolithic TS-1 Tianjin University

2. Model simplification 2.1 General Model Assumption • Aqueous phase and organic phase flow in cocurrent flow at constant flow rate; • Isothermal operating condition of the reactors; • The shape of every channel is regular triangle; • Pressure drop is small and negligible; • The wall as well as the washcoat thickness are small compared to the channel hydraulic radius; • Physical properties (such as density, viscosity, diffusion co-efficient, etc.) are assumed to be constant; • Neglecting the axial dispersion within the ﬂuid phase. Tianjin University

2. Model simplification 2.1 General Model Assumption 2.1.1 The choice of model scales • washcoat (catalyst layer); • single channel; • multi-channel; • entire reactor. To describe the behaviors of a monolith reactor, single channel scale modeling is the most extensively applied at present. At this scale of modeling, it is assumed that every channel in the monolith reactor behaves exactly the same and can represent the entire reactor. Like in the washcoat scale modeling, the behaviors inside the catalyst are still considered. Tianjin University

2. Model simplification Fig.2 Schematic representation of a single square monolith channel: (a) 3-D; (b)cross-section with catalytic walls; (c) cross-section with washcoated walls.[1] [1] Jinwen Chen, Hong Yang, Neil Wang, Mathematical modeling of monolith catalysts and reactors for gas phase reactions, Applied Catalysis A: General 345 (2008) 1–11. Tianjin University

2. Model simplification 2.1 General Model Assumption 2.1.2 Zero Washcoat thickness model According to the SEM images of monolithic TS-1 films, thickness of the washcoat is 3-5 um, which can be neglected compared to the size of the channel. (Zero washcoat thickness (ZWT) model) For the ZWT model, the continuity, species, momentum and energy conservations were solved in the channel. Fig. 3. The computational domains and the boundary conditions of the Zero Washcoat thickness (ZWT) [2] [2] Michael J. Stutz, Dimos Poulikakos, Optimum washcoat thickness of a monolith reactor for syngas production by partial oxidation of methane, Chemical Engineering Science 63 (2008) 1761–1770. Tianjin University

2. Model simplification 2.2 Liquid-Liquid-solid Three-Phase Flow Patterns in the channel Stable flow patterns in microchannel: (a) Slug flow (b) Monodisperse flow (c) Droplets populations flow (d) Parallel flow (e) Annular flow Fig. 4 Stable flow patterns in microchannel Tianjin University

2. Model simplification 2.2 Liquid-Liquid-solid Three-Phase Flow Patterns in the channel The ratio of aqueous phase to the oil phase added in is 3:1. This ratio increases with the progress of reaction, as a result, the oil phase layer becomes thinner. According to the ratio, the physical dimension of the boundary can be calculated. Tianjin University

2. Model simplification 2.2 Liquid-Liquid-solid Three-Phase Flow Patterns in the channel According to this experiment, The speed of reactant mainly comes from the circulation. Fig.5 Water–toluene system flow pattern maps with superficial velocities of two phases as coordinates for different microchannels: (□)Slug flow, (+) Slug-drop flow, (×)Deformed interface flow, (○)Parallel/Annular flow. [3] [3]Madhvanand K., Lioubov K. M., Quantitative prediction of flow patterns in liquid-liquid flow in micro-capillaries, Chemical Engineering And Processing:Process Intensification, 2011, 07, 003 Tianjin University

2. Model simplification 2.2 Liquid-Liquid-solid Three-Phase Flow Patterns in the channel aqueous phase organic phase Fig.6 Cross-sectional images of supposed flow patterns catalyst washcoat cordierite skeleton Because the surface of the TS-1 is hydrophobic, aqueous molecules are hard to be adsorbed to the active centers of the catalyst and the organic molecules are accessible to the active center. Tianjin University

2. Model simplification 2.3 Mass transfer in monolithic catalyst with triangular channels A confusion？ Fig. 7 Concentration profiles of the reactants and product (oxime) in the liquid-liquid-solid reacting system Tianjin University

2. Model simplification 2.3 Mass transfer in monolithic catalyst with triangular channels c aqueous aqueous organic organic organic phase film film phase film Cordierite skeleton Catalyst particle [cyc]org [H2O2]aq [cyc]s [H2O2]i.aq [H2O2]i.org [H2O2]org [H2O2]s [NH3]aq [NH3]i,aq [NH3]i,org [NH3]org [NH3]s [P]aq [P]i,aq [P]i,org [P]org [P]s Fig. 8 Concentration profiles of the reactants and product (oxime) in the liquid-liquid-solid reacting system Tianjin University

2. Model simplification 2.3 Mass transfer in monolithic catalyst with triangular channels Mathematical model Tianjin University

3. Next plan • Formulate the detailed model and identify the flow pattern in the channel; • 2. Study the mass-transfer in the triangular channel; • Establish the mathematical model and give the model equations; • 4. Determine the parameters in the equations. Tianjin University

Thank You !

Reporter: Sun Rui Supervisor: Xin Feng 2013-7-10