Question

As a first step in the production of nitric acid, ammonia is oxidized to form nitric oxide: 4NH3 + 5O2→4NO + 6H2O

A side reaction also occurs:
2NH3 +3/2O2→N2 +3H2O

A reactor is designed to carry out this reaction isothermally at 600°C, with pure oxygen fed to the reactor in 50% excess. At these conditions, all components are in the gas phase. The conversion of ammonia is 80%, and the selectivity ratio of NO to N2 in the product stream is 15:1. The reactor products are fed to a separator where 75% of the NH3 and O2 are recycled and combined with a fresh feed. The remainder of the reactor products are removed as a product. Assume a feed flowrate of 2100 SLPM of ammonia. (25 points)

1. Determine the flow rate, in moles per second, of all the products leaving the reactor.

2. Determine the flowrate and composition of the fresh feed in moles per second.

Answer 1

I have assumed that the given conversion is the overall conversion which is defined as the ratio of moles of NH3 reacted overall to the moles of NH3 fed into the system.

The required material balances with the use of stoichiometry is shown below.