Gasoline hydrorefining

Besides the hydrogenation processes of the petroleum industry discussed above, the hydrogenation of benzene to cyclohexane is the most important large-scale indus-trial hydrogenation reaction. Most of the cyclohexane thus produced is used in the manufacture of polyamides. 

Nickel as well as platinum and palladium are the most important catalysts used in the liquid or gas phase usually in the temperature range of 170-230°C and pressure of 20-40 atm. Since the reaction is highly exothermic [Eq. (11.91)], efficient heat removal is required to ensure favorable equilibrium conditions and prevent isomerization of cyclohexane to methylcyclopentane  

One of the most important processes is IFP s liquid-phase hydrogenation technology330-332 applying a Raney nickel catalyst under mild conditions (200-240°C, 15-30 atm). The liquid phase with the suspended catalyst is circulated with an 

Numerous other technologies, mainly gas-phase hydrogenations, were developed over the years (Sinclair-Engelhard,333,334 Hytoray,335,336 Arco,337 DSM,338 UOP339). The Arco and DSM processes operate at 400°C and under 25-30 atm. Despite the high temperature, isomerization is negligible because of the very short contact time. 

The soluble nickel catalyst developed by IFP for the oligomerization of alkenes applied in different Dimersol processes (see Section 13.1.3) can also be used in benzene hydrogenation to replace Raney nickel (IFP cyclohexane process).340 

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Gasoline hydrorefining is applied to remove polymerizable by-products (isoprene, cyclopentadiene, styrene and indene) from stream-cracked gasoline to prevent gum formation. Partial hydrogenation of dienes to monoalkenes and the hydrogenation of... 

A second aspect of the reactivity of the gas oil pyrolyzate is the impact it has on catalyst performance. The catalysts in many of the hydrorefining schemes developed for pyrolysis gasoline are particularly sensitive to control of the distillation end point and to the inclusion of substantial quantities of sulfur. 

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