Find the Composition of Product Gas

Methane reacts with 100 % excess oxygen to form formaldehyde and water. However, in an undesired side reaction, some of the methane is combusted. If the conversion of CH₄ is 60 % and the selectivity of formaldehyde to CO₂ is 5:

a. Find the composition of the product gas and the yield using the atomic species method.

b. To try to increase the overall conversion of CH₄, you decide to add a recycle stream. The products exit the reactor and enter a separator where 90 % of the exiting CH₄ and 50 % of the exiting O₂ is recycled. Keeping the conversion to the reactor and the selectivity the same and using a basis of 100 moles of methane to the reactor, show whether this would be effective or not.

c. Let's see what the effect of changing the molar flow rate of CH₄ into the system and the percent excess oxygen. Write a VBA program that takes in a molar flow rate and excess oxygen (best to put it in a fraction), creates a matrix to solve for your unknown flow rates, solves for them, and then prints out the yield and conversion for the different flow rates. You should have five different flow rates and five excesses in each one. Your spreadsheet should look like the template on the next page (with the numbers and unknown names filled in). This is just an example. You will have to use a nested next loop.  What can you conclude about the effects of the changes?