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Why is a catalyst used when butane is isomerized into isobutane?

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Two diagrams show the three-dimensional structure of a methane molecule: panel A uses a ball-and-stick model with a central carbon atom connected to four hydrogen atoms in a tetrahedral arrangement, while panel B illustrates the bond angle of 109.5 degrees and bond length of 1.09 angstroms between carbon and hydrogen atoms. — isomerism Tetrahedral geometry of methane: (A) stick-and-ball model and (B) diagram showing bond angles and distances. (Plain bonds represent bonds in the plane of the image; wedge and dashed bonds represent those directed toward and away from the viewer, respectively.)

In the context of chemistry, a catalyst is used in the isomerization of butane into isobutane to facilitate the chemical transformation of the straight-chain hydrocarbon into its branched-chain isomer.

While the process involves heating butane to 100° C or higher, the catalyst is essential to enable and accelerate this structural rearrangement efficiently. In industrial petroleum refining, this reaction is typically performed using aluminum chloride supported on alumina and promoted by hydrogen chloride gas.12

The use of a catalyst is vital because it allows the reaction to proceed under conditions that make the production of branched-chain hydrocarbons—which serve as superior motor fuels—commercially viable. By lowering the activation energy required for the molecules to rearrange their structure, the catalyst ensures that the conversion of the more abundant normal butane into the high-octane isobutane can occur at a practical rate.12