Chemical Reaction Engineering Module

Understand and Optimize Chemical Processes and Designs

Mathematical models help scientists, developers, and engineers understand processes, phenomena, and designs of reacting systems. The Chemical Reaction Engineering Module, an add-on to the COMSOL Multiphysics® software platform, provides user interfaces for creating, inspecting, and editing chemical equations, kinetic expressions, thermodynamic functions, and transport equations. After developing a validated model, it can be used for studying different operating conditions and designs of reacting systems and transport phenomena. Solving the model equations over and over for different inputs leads to a true understanding of the studied system. Additionally, the Chemical Reaction Engineering Module, along with other tools in COMSOL Multiphysics®, provides state-of-the-art mathematical and numerical methods adapted for optimization and parameter estimation of chemical systems.

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A plate reactor model with an isosurface plot showing the concentration of a chemical species in the Viridis color table.

What You Can Model with the Chemical Reaction Engineering Module

Model transport phenomena and chemical reactions in many industrial processes with the COMSOL® software.

A 1D plot showing the concentration in two tanks.

Ideal Tank Reactors

Simulate ideal systems such as batch, semibatch, continuous stirred tank, tubular, and plug flow reactors.

A model of a tank showing the concentration of acetaldehyde in fermenting beer in rainbow.

Food Processing

Study and design processes and phenomena in the food industry.

A monolithic converter model with the conversion shown in a Rainbow color table and temperature distribution shown in a Heat Camera color table.

Automotive and Petrochemical

Model catalytic converters and filters in exhaust systems.

A detailed view of the temperature and flow of a four-cylinder engine model.


Analyze how mixture properties depend on composition, pressure, and temperature.

A detailed view a protein adsorption model showing the concentration.

Mixing and Separation

Design mixing and separation processes in the fine chemicals industry.

A detailed view of the solute concentration of a packed bed reactor model.

Environmental Sciences

Investigate elimination of pollutants in effluent streams by modeling transport and adsorption in, for example, fixed porous beds.

A detailed view of the contaminant transport and concentration of a hollow fiber dialysis device.

Medical Technology

Test the design requirements for various components in medical equipment such as dialysis membranes.

A detailed view of the concentration of a drug release model.

Pharmaceutical Processes

Optimize designs and processes for chemical and biopharmaceutical applications.

A detailed view of the molecular flux fraction of a UHV/CVD model.

Chemical Vapor Deposition

Model growth on a substrate surface through adsorption and deposition in CVD processes such as in wafer manufacturing.

A detailed view of the concentration of an electrokinetic valve.

Electrokinetic Effects

Model electrophoretic separation and transport in columns and other microfuidic systems.

Overview of the Modeling Strategy and Workflow

Realistic descriptions of reacting systems in scientific and engineering studies often need to incorporate both transport phenomena and chemical reactions to understand and optimize a process or design. The Chemical Reaction Engineering Module is tailored for the typical workflow in chemistry and chemical engineering investigations, which involve the following incremental steps:

  • Study reaction mechanisms in ideal, perfectly mixed systems
  • Calculate kinetic, thermodynamic, and transport properties
  • Extend the investigations to space-dependent systems
    • Transport of chemical species
    • Heat transfer
    • Fluid flow
    • Electrokinetic effects

The workflow described above can be applied in many different fields that involve chemical reactions and in all scales, from nanotechnology and microreactors to environmental studies and geochemistry. The whole process, from model definition to the presentation of the results, is documented in the software for transparency and reproducibility.

Features and Functionality in the Chemical Reaction Engineering Module

The Chemical Reaction Engineering Module provides a built-in workflow for simulating perfectly mixed systems in 0D followed by transport phenomena in 2D and 3D.

A closeup view of the Model Builder with Reaction Engineering node highlighted and simulation results of a monolith reactor model in the Graphics window.

Defining Reaction Kinetics

The first step in modeling any system is establishing the material balances. Using the Reaction Engineering interface, you can enter chemical equations and automatically obtain the material balance equations for the chemical species in the system and the energy balance equations for the system. When you type in the reaction mechanism, the kinetic expressions as a function of the species concentrations are derived automatically from the mass action law for elementary steps. You can also type in your own analytical expressions for the reaction rate as a function of the species concentrations and temperature.

The material balances and the reaction kinetic expressions give the ordinary differential equations that are formulated automatically by the software. For a perfectly mixed batch reactor, the solution to the equations gives the composition of the reacting mixture with time.

The COMSOL Multiphysics UI showing the Model Builder with the Generate Space-Dependent Model node selected, the corresponding Settings window, and the concentration of a tortuous reactor in the Graphics window shown in the AuroraBorealis color table.

Generating Space-Dependent Models

Once you have a working model for a perfectly mixed system, you can use this model to automatically define material, energy, and momentum balances for space-dependent systems. The transport properties calculated in the Reaction Engineering interface (for example, heat capacity, thermal conductivity, viscosity, and binary diffusivity) automatically transfer to the physics interfaces for chemical species transport, heat transfer, and fluid flow. This functionality allows you to refine and perfect your kinetics and thermodynamics expressions of the chemical reactions before moving to 2D, 2D axisymmetric, and 3D models.

A close-up view of the Model Builder with the Dispersed Phase Transport of Diluted Species node selected and an extraction column model in the Graphics window.

Chemical Species Transport

Modeling of transport phenomena in reacting systems involves the description of the chemical species in so-called multicomponent transport models. The Chemical Reaction Engineering Module contains sophisticated models for multicomponent transport in the Transport of Concentrated Species interface, where you can select between the Maxwell–Stefan formulation and the mixture-averaged models for multicomponent transport. For diluted solutions, you can also choose the Transport of Diluted Species interface, which treats cases where the interactions in the solution are dominated by solute–solvent interactions. The Dispersed Two-Phase Flow with Species Transport interface can be used to describe chemical species transfer between two immiscible fluid phases. The chemical species transport equations are also available for porous media, for example, to include Knudsen diffusion. The dusty gas diffusion model is also included. The formulation of the mass balance model as well as the transport properties can be obtained directly from chemical equations when generating a space-dependent model from the Reaction Engineering interface.

A closeup view of the Transport Properties settings and the concentration of an electrokinetic valve in the Graphics window.

Electrokinetic Effects

When modeling the transport of diluted or concentrated species, you can include electric fields as driving forces for transport for the modeling of electrolytes and ions. The Nernst-Planck and Electrophoretic Transport interfaces are dedicated to the modeling of electrolytes and can include the formulations of Poisson’s equation or the electroneutrality condition for the charge balance in the electrolyte. Applications of this functionality include electrokinetic valves, electroosmotic flow, and electrophoresis.

A closeup view of the Thermodynamic System settings and a 1D plot of a phase envelope model in the Graphics window.

Thermodynamic Properties Database

The Chemical Reaction Engineering Module contains a thermodynamic properties database, which you can use to calculate properties for gas mixtures, liquid mixtures, gas–liquid systems at equilibrium (flash calculations), liquid–liquid systems, and gas–liquid–liquid systems at equilibrium. There is a variety of thermodynamic models that can be used to calculate density, heat capacity, enthalpy of formation, enthalpy of reaction, viscosity, thermal conductivity, binary diffusivity, activity, and fugacity. Read more about this functionality on the Liquid & Gas Properties Module page, all of which is included in the Chemical Reaction Engineering Module.

The thermodynamic properties database can be used to create a so-called property package for a specific reacting system by selecting the chemical species present in the system, the desired properties, and the thermodynamic model. When defining reaction mechanisms, the reactants and products can be matched with the chemical species in the property package defined by the thermodynamic properties database. This matching automatically links the functions and equations generated by the property package to the model of the reacting system.

A closeup view of the Model Builder with the Experiment node highlighted and a 1D plot of a DNA degradation model in the Graphics window.

Parameter Estimation

Studies of chemical reactions and reaction mechanisms usually rely on parameter estimation of frequency factors, activation energies, and other parameters that may quantitatively describe experimental observations. The Chemical Reaction Engineering Module can be combined with the Optimization Module in order to access a dedicated interface for chemical kinetics.

The typical workflow for the estimation of model parameters for a certain assumed reaction mechanism is as follows. You first select the model parameter to estimate, such as the rate constants, and enter initial values and scales for the parameters. Then, you can link to the file that contains the experimental data, matching up the data columns with the model variables. Once you have run the parameter estimation, you can compare the model results and the experimental measurements in postprocessing.

A closeup view of the Model Builder with the Transport of Diluted Species node highlighted and a packed bed reactor model in the Graphics window.

Fluid Flow

The fluid flow functionality included the Chemical Reaction Engineering Module can handle laminar and porous media flow. Additionally, when combined with the CFD Module, there are ready-made couplings for the modeling of chemical species transfer in turbulent flow. The formulation of the fluid flow model as well as the viscosity and density can be obtained directly from chemical equations when generating a space-dependent model from the Reaction Engineering interface.

A closeup view of the Model Builder with the Heat Transfer in Fluids node highlighted and the velocity magnitude of an engine coolant model in the Graphics window.

Heat Transfer

The heat transfer functionality included in the Chemical Reaction Engineering Module can account for heat transfer by conduction, convection, and radiation. The radiation term is given by surface-to-ambient radiation, while the Heat Transfer Module is required for surface-to-surface radiation and radiation in participating media. The heat transfer capabilities in the Chemical Reaction Engineering Module include heat transfer in fluids, solids, and porous media. The formulation of the heat transfer model, as well as the thermodynamic and transport properties, can be obtained directly from chemical equations when generating a space dependent model from the Reaction Engineering interface.

Surface Reactions and Heterogeneous Catalysis

Surface reactions are typical for heterogeneous catalysis as well as for surface deposition processes such as chemical vapor deposition. They are found in the bulk chemical industry, for example, in the Haber–Bosch process for the production of ammonia and in microsensors for the detection of very low amounts of tracers that can adsorb on surfaces and be detected by, for example, a change in electrical properties.

In transport-reaction models, surface reactions can be treated as boundary equations coupled to the boundary conditions for the transport and reaction equations in the bulk. This would be typical for models below or up to the microscopic scale. Alternatively, in porous media, these reactions are treated in a similar fashion as homogeneous reactions but include the specific surface area (area per unit volume of the porous material) and the effective transport properties. This would be typical for models both in the microscopic scale and the macroscopic scale, so-called multiscale models.

The Chemical Reaction Engineering Module includes ready-made formulations for heterogeneous catalysis for both cases: surface reactions on boundary faces as well as surface reactions distributed over a homogenized porous catalyst. For porous catalysts, multiscale models are predefined to describe bimodal pore structures. Such structures may consist of microporous pellets packed to form a macroporous pellet bed.

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