Industrial polypropylene production:\nWhich polymerisation mode is most closely associated with large-scale commercial manufacture of polypropylene?

Introduction / Context:
Polypropylene (PP) is produced via coordination catalysis (Ziegler–Natta or metallocene). Reactor and process choices (bulk/slurry/gas phase) impact tacticity, molecular weight, and product form. Many exam syllabi cite “bulk” (slurry/loop) processes for PP because the polymer is produced essentially in the liquid monomer or hydrocarbon medium at relatively low pressure compared to radical routes for LDPE.

Given Data / Assumptions:

• Coordination polymerisation yields highly stereoregular PP.
• Industrial processes include bulk (slurry/loop) and gas-phase reactors.

Concept / Approach:
“Bulk” is the classical answer in educational contexts, referring to slurry/loop reactors using liquid propylene (and/or diluents) as reaction medium. Emulsion polymerisation is not used for PP; solution processes apply more to other polymers; suspension is not the common PP route. Gas-phase is also widely used in practice, but “bulk” remains the traditional textbook selection for MCQs framed this way.

Step-by-Step Solution:

Verification / Alternative check:
Process histories from major licensors describe loop slurry (“bulk”) and gas-phase routes; among provided options, bulk is the representative educational answer.

Why Other Options Are Wrong:

• Emulsion/suspension: typical for vinyl chloride, styrene, but not PP.
• Solution: not the mainstream PP route cited in basic MCQs.

Common Pitfalls:
Overemphasising gas-phase while ignoring that the question asks for a single “employs” mode; many syllabi emphasise bulk.

Final Answer:
Bulk