Question

Suppose the feed to a continuous reactor for ammonia synthesis consists of 100 mol/s of nitrogen, 300 mol.s-1 of hydrogen, and 1 mol/s of argon. For a fractional hydrogen conversion of 0.6, calculate the outlet flow rate of hydrogen, the extent of reaction, and the outlet flow rates of nitrogen and ammonia.

N2+3H2=2NH3

Answer 1

Reaction: N₂+3H₂=2NH₃

where _NH3 is the Molar flow rate of ammonia at exit

_N2, _H2 and _Ar is the Molar flow rates of nitrogen, hydrogen and argon, respectively at the exit

Molar flow rate at exit can be expressed in terms of extent of reaction as

where _i0 and _i is the Molar flow rate at inlet and outlet, respectively

is the Extent of reaction

v is the stoichiometric coefficient. It is positive for products and negative for reactants.

The outlet flow rates are

For a fractional hydrogen conversion, f=0.6, the fraction of H₂ unreacted is 1-f=1-0.6=0.4.

Thus the molar flow rate of H₂ at exit, _H2, is

Substitute the value of  _H2 in Equation 3

Substitute the value of   in Equation 1

Substitute the value of   in Equation 2

Thus the outlet flow rate of hydrogen is _H2=120 mol/s, extent of reaction is =60 mol/s, outlet flow rate of nitrogen is _N2=40 mol/s and outlet flow rate of ammonia is _NH3=120 mol/s