Polymer gasoline manufacture: In catalytic polymerization units that convert light olefins to higher-octane gasoline components, which catalyst system is commonly employed?

Introduction / Context: Catalytic polymerization (historical “polymer gasoline”) combines light olefins such as propylene and butylenes into higher molecular weight gasoline components. The process predates modern oligomerization/alkylation technologies and uses specific acid catalysts to drive carbon–carbon bond formation.

Given Data / Assumptions:

• Feed: C3–C4 olefins from FCC or thermal cracking.
• Objective: produce high-octane gasoline blend stock.
• Catalyst options include acid and non-acid systems.

Concept / Approach: A classic catalyst for polymerization to gasoline is phosphoric acid supported on kieselguhr (siliceous support). Strong solid acids promote olefin polymerization/oligomerization. Aluminium chloride is a Lewis acid for Friedel–Crafts reactions in different contexts; nickel is primarily for hydrogenation; vanadium pentoxide serves in oxidation (e.g., SO2→SO3), not olefin polymerization; an inert zeolite Y without an acid function would not be active for polymerization.

Step-by-Step Solution:

Verification / Alternative check: Refinery process summaries list solid phosphoric acid (SPA) catalysts as standard for polymer gasoline/oligomer units, producing high-octane streams rich in branched components.

Why Other Options Are Wrong:

Common Pitfalls: Confusing polymerization with alkylation or hydrogenation; all three use different catalytic functionalities.

Final Answer: phosphoric acid supported on kieselguhr