Catalyst for catalytic polymerisation to produce “polymer gasoline” (olefin polymer petrol)

Introduction / Context:
“Polymer gasoline” refers to high-octane gasoline-range hydrocarbons made by polymerising light olefins (like propene, butenes). The historical industrial process used a specific acid catalyst on a solid support.

Given Data / Assumptions:

• Feed contains C3–C4 olefins from cracking streams.
• Process goal is to make motor-fuel-range polymers/oligomers with high octane.

Concept / Approach:
Phosphoric acid (H3PO4), typically supported on kieselguhr or other carriers, is the classical catalyst for catalytic polymerisation to polymer gasoline. While sulfuric acid has been used in alkylation or as a liquid acid in some polymerisation contexts, the canonical answer for “polymer gasoline catalyst” in refinery practice is H3PO4 on solid support. AlCl3 is more aligned with Friedel–Crafts alkylation, and zeolites are typical of modern FCC/oligomerisation routes but not the textbook polymer gasoline catalyst.

Step-by-Step Solution:

Verification / Alternative check:
Classic refinery texts list phosphoric acid polymerisation units producing high-octane polymer gasoline from C3/C4 olefins.

Why Other Options Are Wrong:

• H2SO4: more typical for alkylation; not standard answer here.
• AlCl3/Zeolite: different process families and conditions.
• “Both” overgeneralizes across distinct processes.

Common Pitfalls:
Conflating polymerisation with alkylation; both upgrade olefins but use different catalysts and mechanisms.

Final Answer:
H3PO4