Gas-Phase Catalytic Dehydrogenation of 1-Butene to 1,3-Butadiene

temperature (K)

900

pressure (atm)

1

vary T and P

comparison with Aspen Plus at 900 K & 1 atm

1,3-Butadiene can be produced by gas-phase catalytic dehydrogenation of 1-Butene in the reaction

C

4

H

8

⇌

C

4

H

6

+

H

2

. To suppress the reverse reaction, steam (acting as an inert gas) is added. The dilution factor is equal to the number of moles of steam added per mole of 1-Butene. The Demonstration computes the equilibrium conversion vs. the dilution factor using Gibbs free energy minimization. The user can set values of the temperature

T

, expressed in Kelvin, as well as the pressure

P

, expressed in atm. Here, only low to moderate values of the pressure are allowed. Thus, the gas mixture behaves as an ideal gas.

In accordance with Le Chatelier's principle, you can verify that:

(1) the conversion is favored when you increase the temperature, since the reaction is endothermic (

o

ΔH

298.15

=109.780kJ/mole

).

(2) the forward reaction is favored by low pressures and high dilution factors. Indeed, there are more moles of product than reactant (

Δν

i

=+1

).

Finally, the results of our calculations at

T=900K

and

P=1atm

(red dots) agree very well with those obtained with Aspen Plus (chemical process optimization software) using the built-in module entitled RGIBBS (green triangles in snapshot 4).