Advanced Reaction Engineering, Coursework, LSBU, UK

Part 1

Coursework Aim

In this part of the coursework, you will determine the mechanism and develop a rate law for a catalytic reaction from experimental data.

Question 1

Find the rate law for the following catalytic reaction based on the data provided.
                                  𝐴𝐴 → 𝐵𝐵

a) Write a full mechanism in the form of a system of reactions describing
adsorption, surface reaction, and desorption. Specify the type of adsorption
mechanism (molecular, dissociative) and reaction mechanism(s) (single site,
dual site, Eley-Rideal) determined to fit the data provided.

b) Determine the rate law(s) for each step (adsorption, surface reaction,
desorption).

c) Find the rate-limiting step and express the rate law in terms of unknown
constants and partial pressures.

d) Solve for unknown constants by fitting the model to the data computationally
(MATLAB is recommended) and then express the rate law solely in terms of
partial pressures. Demonstrate that the model fits the data.

Learning Outcomes

This coursework will fully or partially assess the following learning outcomes for this module.

Knowledge and Understanding

• A knowledge of reactor behaviour for homogeneous and heterogeneous systems. An understanding of reaction engineering so that students can apply the principles to the solution of relevant engineering problems and to the design of reaction processes.

In this coursework, you will use reaction engineering principles to model a heterogeneous catalysis process. This would be the first step towards designing a reactor for this process

Intellectual Skills

• Formulate dynamic material and energy balances to give a good representation of a chemical reactor for simple and complex reactions. Identify mixing and dynamic effects in chemical reactors. Construct models for non-ideal reactors. Make quantitative descriptions of heterogeneous reaction processes.

In this coursework, you will formulate a site balance for a catalyst surface in order to develop a quantitative model of a heterogeneous catalytic reaction process.

• Use a mathematical approach for design, optimisation, and control of chemical reactors.

In this coursework, you will use both symbolic and computational mathematics to develop this quantitative model.

Practical Skills

• Evaluate the performance of chemical reactors. Make provision for heterogeneous processes. Specify temperature profiles. Specify designs for homogeneous and heterogeneous reactors. Optimise reactor performance.

Part 2

Coursework Aim:

• To apply the concepts covered during the lectures to practical reactor
  engineering design problems.
• To develop mathematical and computational skills for the solution of reactor
  engineering design problems.
• To develop critical thinking about reactor design and its application in solving
  current global issues.

Coursework Details:

This part of the coursework comprises two questions. The questions are about solving a series of reactor design problems where the set of equations is first specified and then solved to produce a selection of reaction profiles, such as concentration vs time, and reactor temperature vs time. Different operating regimes are considered, e.g. batch, isothermal, non-isothermal, catalytic, non-catalytic, etc. The solution of the equations may require the use of specialised engineering software, as shown during the lectures and tutorials. This part of the coursework is worth 50% of the module.

General instructions. Provide a clear development and presentation of the equations as well as the MATLAB code (or a copy of any file/software) used to
solve the equations, when applicable. The code must be presented either as
text in a Word file or as an independent .m (MATLAB) file, or any other workable file. The code must work properly when run by the marker. If the code/working file is not presented, marks will be reduced. The quality of the document will be considered in the marking.

Question 2

The following consecutive first-order reactions represent a hydrogenation
process:

The reaction takes place at 250 °C, and at this temperature, the reaction rate
coefficients are 𝑘𝑘1 = 0.055 min-1 and 𝑘𝑘2 = 0.008 min-1. For a liquid-phase
reaction carried out in a batch reactor where only A is charged with a
concentration of 50 mol L-1, obtain the following:

a) Present the development and the final expressions needed to determine the concentration of the different species as a function of time.

b) Present a plot showing the concentration profiles of the different species as
a function of time (up to 500 min), when no B or C are present initially.

c) The time needed to achieve 80% conversion.

d) The concentration of the different species at 500 min.

Question 3

The elemental irreversible liquid-phase reaction:

takes place in a steady-state 200 dm3 PFR, where species A and B are fed at 30 °C at a flow rate of 10 mol min-1 and 10 mol min-1, respectively. The entering volumetric flowrate is: 𝑣𝑣0 = 10 dm3 min-1. The following thermodynamic data is available:

For the case when a heat exchanger operating in co-current mode is placed
(with a UA = 1200 cal min-1 K-1) in the reactor and the working fluid temperature is constant at 70 °C:

i. Obtain the expressions to determine the concentration of the different species, and the reactor temperature, as a function of the space-time, 𝜏𝜏.

ii. Plot the concentrations of the different species as a function of 𝜏𝜏.

iii. Plot the temperature of the reactor as a function of 𝜏.

v. Determine the concentrations and the temperature at the exit of the
reactor.

v. Determine the concentrations and the temperature when the values
of the residence time is 10 min.

Learning Outcomes

This coursework will fully or partially assess the following learning outcomes for this module.

Knowledge and Understanding

• A knowledge of reactor behaviour for homogeneous and heterogeneous systems. An understanding of reaction engineering so that students can apply the principles to the solution of relevant engineering problems and to the design of reaction processes.

Intellectual Skills

• Formulate dynamic material and energy balances to give a good
  representation of a chemical reactor for simple and complex reactions.
• Use a mathematical approach for the design of chemical reactors.

Practical Skills

• Evaluate the performance of chemical reactors. Make provision for
  heterogeneous processes. Specify temperature profiles.

Transferable Skills

• Apply principles of advanced reaction engineering to complex processes in which chemical reactions occur.

Answer

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