Production of Cyclohexane through Catalytic Hydrogenation of Benzene

What is cyclohexane?

Cyclohexane is a cycloalkane with the molecular formula C₆H₁₂. Cyclohexane is mainly used for the industrial production of adipic acid and caprolactam.

Physical properties

Cyclohexane is a colourless, mobile liquid with a mild, sweet odour. It is slightly soluble in water and soluble in alcohol, acetone, benzene, ethanol, ethyl ether, olive oil, and carbon tetrachloride.

Melting Point: 6.47°C

Boiling Point: 80.7°C

Formula weight 84.161

Chemical properties

Cyclohexane is a flammable, non-corrosive liquid.

Application of cyclohexane

Most cyclohexane goes into the production of intermediates for nylon, which has a variety of common applications such as clothing, tents and carpets as well as thermoplastics. Cyclohexane is also used as a solvent in chemical and industrial processes and recently has been substituted for benzene in many applications. Chevron Phillips Chemical also offers other solvents through our Specialty Chemicals Division.

Process flow Diagram

Process description

Reaction involved: Benzene + Hydrogen                Cyclohexane (Vapour Phase)

Reactor Used: Catalytic Packed Bed Conversion Reactor

Reactor conditions: Outlet Temperature = 497 K, Pressure Drop = 1.02 atm

Catalyst Used: Nickel Based

Fresh benzene and excess hydrogen are preheated to a temperature of 422 K and sent to a packed bed reactor. A vapour phase reaction occurs in the reactor at 497 K which converts benzene to cyclohexane through catalytic hydrogenation of benzene. The conversion of this reaction is about 99%. The reactor products are cooled to 370 K and sent through a pressure reduction valve which reduces the pressure of the stream. A two-stage separator separates the product cyclohexane from unreacted hydrogen and methane- first at a high pressure and then at a lower pressure. The unreacted hydrogen-methane mixture is recovered from the top of the flash column and is sent to a splitter having a splitting ratio of 9:1. The smaller stream is sent as a recycle stream and mixes with fresh hydrogen, while the rest is drawn out as fuel gas for incinerators. The bottom stream of the flash column having cyclohexane is sent as feed to a distillation column for further purification. The residue from the column has our desired product with a purity of 99.5% (wt/wt) cyclohexane.

Benefits of hydrogenation process.

The hydrogenation of benzene, which can be carried out in both liquid and gaseous phases, in the presence of different metal-based catalysts. The conversion of this reaction is about 99%.

Blog by

Vishwajeet Mahamuni

Jayesh Mane

Sakshi Niphade

Ritik Odpalliwar

Onkar Pardeshi

Aditya Pawar