MATLAB Examples

zHW: Multiple Independent Reactions

Formaldehyde is produced on an industrial scale by the incomplete oxidation of methanol in air. Principle by-products include formic acid, carbon dioxide, and carbon monoxide. Find a set of independent reactions for this reaction system.

Contents

Chemical Species

The first step is to provide a list of all chemical species partcipating in the reaction system. Use molweight to verify correct entry of this list of species.

species = { ...
    'CH3OH', ...     % Methanol
    'O2', ...        % Oxygen
    'CH2O', ...      % Formaldehyde
    'CHOOH', ...     % Formic Acid
    'CO', ...        % Carbon Monoxide
    'CO2', ...       % Carbon Dioxide
    'H2O'};          % Water

molweight(species);
Species                    Mol. Wt.
-------                    --------
CH3OH                         32.04
O2                            32.00
CH2O                          30.03
CHOOH                         46.03
CO                            28.01
CO2                           44.01
H2O                           18.02

Independent Reactions

The rank of the stoichiometric matrix indicates the number of independent reactions that are possible.

V = stoich(species);
disp(' ');
disp('V = ');
disp(V);
fprintf('\nNumber of Independent Reactions = %g\n',rank(V));
 
V = 
    -1     0     0     0
     0    -1     0     0
     0     0    -1     0
     0     0     0    -1
     3    -2     2     1
    -2     2    -1     0
     2     0     1     1


Number of Independent Reactions = 4

Displaying the Independent Reactions

disp_reaction(V,species);
CH3OH + 2 CO2 <=> 3 CO + 2 H2O
O2 + 2 CO <=> 2 CO2
CH2O + CO2 <=> 2 CO + H2O
CHOOH <=> CO + H2O