# Chemical Reactors I

## Objectives

The main goal of this course is to provide the students with the basic concepts of Chemical Reaction Engineering, in such a way that on the end of the course the students will be able to:

To determine a kinetic law corresponding to a given chemical reaction, calculating the kinetic parameters;

To derive a kinetic law from a mechanistic proposal;

To design ideal chemical reactors working under isothermic or non-isothermic conditions.

## General characterization

##### Code

10822

##### Credits

6.0

##### Responsible teacher

Isabel Maria de Figueiredo Ligeiro da Fonseca

##### Hours

Weekly - 5

Total - 67

##### Teaching language

Português

### Prerequisites

There are not.

### Bibliography

H. Scott Fogler

Elements of Chemical Reaction Engineering

4rd edition, Prentice-Hall, 2006.

Octave Levenspiel

Chemical Reaction Engineering

4th edition, John Wiley & Sons, 1998.

J. M. Smith

Chemical Engineering Kinetics

3rd edition, McGraw-Hill, 1981.

Jacques Villermaux

Génie de la réaction chimique. Conception et fonctionnement des réacteurs.

2eme tirage, Lavoisier-technique et documentation, 1985.

### Teaching method

The teaching methods include:

- Lectures with PP presentations;

- Laboratory sessions and results modeling using Excel;

- Problem solving sessions.

### Evaluation method

The course evaluation is composed by a written part and a practical part. The written part consists in 3 tests and/or in a final exam. The practical part consists in projects based in the laboratory sessions and in the theoretical-practical sessions. Each project is executed by groups of three or four students, is electronically delivered to the instructors and leads to a single grade. This grade is obtained subsequently to the oral presentation of the final report.

The course final grade is the weighted average of the written and practical parts, with weights of 75% and 25%, respectively.

## Subject matter

LECTURES

Mole Balances

Classification of ideal chemical reactors: Batch reactor, continuous tank stirred reactor (CSTR), plug flow reactor (PFR).

Definition of reaction rate.

The general mole balance equation.

The mole balance equation applied to Batch, CSTR and PFR.

Concept of transient state and steady state.

Graphical methods on reactors design.

Definition of conversion.

The mole balance of batch reactor.

Flow reactors: concept of space-time.

Design equations for CSTR and PFR.

Graphical sizing of flow reactors based on the plot 1/(.rA) versus X. Reactors in series.

Graphical reactors sizing based on the plot Concentration versus time.

Stoichiometry and rate law.

Basic definitions: elementary reactions; molecularity; kinetic parameters: kinetic constant and reaction order; non-elementary reactions; reversible reactions.

Batch reactors: constant-volume reactors and variable-volume reactors.

Flow reactors: constant volumetric flow rate systems and variable volumetric flow rate systems.

Design of isothermal reactors

Batch Reactors - optimising the operation time and conversion.

Continuous reactors; association of CSTRs; cases of constant and variable volumetric flow rate; case of pressure drop in the PFR; reversible reactions.

Unsteady state operation: start-up of a CSTR; semibatch reactor with constant molar feed; reactive distillation.

Determination of kinetic parameters: the differential and integral methods of data analysis; the half-lives method; the excess concentration method; the method of initial rates.

Homogeneous non-elementary reactions: the hypothesis of the rate limiting step; the pseudo-steady-state hypothesis; enzymatic reactions.

Non-isothermal reactors: the energy balance equation; continuous-flow reactors at steady state; adiabatic operation; reversible reactions; PFR under non-isothermal, non-adiabatic operation; multiple steady states in a CSTR: a brief looking on the steady states stability; the ignition-extinction diagram; unsteady state operation – the batch reactor.

Multiple reactions: selectivity and yield. Parallel and consecutive reactions.

Nonideal reactors

Characterization of flow by use of tracers

Modeling real reactors by association of ideal reactors

LABORATORY SESSIONS

Experimental determination of a kinetic curve, by using the hydrolysis reaction of ethyl acetate. Graphical sizing of flow reactors by using the kinetic data obtained in the lab session. Use of a spreadsheet for data treatment.

Determination of the global reaction order for the ethyl acetate hydrolysis, by using the method of initial reaction rates.

Determination of the partial orders for the same reaction by using the excess reactant method.

Evaluation of the activation energy for the same reaction.

Hydrolysis of ethyl acetate on a non-isothermal laboratory PFR. Evaluation of the heat transfer coefficient.

## Programs

Programs where the course is taught: