Question

Identify catalyst used in manufacturing of HDP.

• A. Zieglar - Natta
• B. Peroxides
• C. Lindlar's
• D. Magnesium oxide

Hint:

Link the polyethylene types directly to their catalysts in your mind: Peroxides create Low-Density Polyethylene (LDP) via radicals, while Ziegler-Natta creates High-Density Polyethylene (HDP) via coordination!

Answer 1

The Correct Option is A

Step 1: Understanding the Question:
The question asks for the identity of the specific chemical catalyst system utilized in the industrial synthesis of High-Density Polyethylene (HDP / HDPE).

Step 2: Key Formula or Approach:
High-Density Polyethylene (HDP) is synthesized by the coordination polymerization of ethene at lower temperatures and pressures. This stereospecific linear polymer production relies critically on a coordination catalyst system consisting of titanium tetrachloride and triethylaluminium, universally known as the Ziegler-Natta catalyst: $$n \, \text{CH}_2\mathrel{=}\text{CH}_2 \xrightarrow{\text{Ziegler-Natta Catalyst}} \mathrel{-}(\text{CH}_2\mathrel{-}\text{CH}_2)_n\mathrel{-}$$

Step 3: Detailed Explanation:
Let's review the roles of the listed catalyst choices: 1.

Ziegler-Natta Catalyst: A combination of $\text{TiCl}_4$ and $\text{Al(C}_2\text{H}_5)_3$. It allows ethene to polymerize linearly with minimal branching, creating closely packed chains that result in high density (HDP).
2.

Peroxides: Used as free-radical initiators to manufacture Low-Density Polyethylene (LDP), which leads to significant chain branching and a lower density.
3.

Lindlar's Catalyst: Partially deactivated palladium on calcium carbonate ($\text{Pd/CaCO}_3$) used to selectively reduce alkynes to cis-alkenes.
4.

Magnesium Oxide: A basic oxide used as a structural promoter or refractory material, not involved in polymerizing ethene.

Step 4: Final Answer:
The catalyst used for manufacturing HDP is the Ziegler-Natta catalyst, which corresponds to option (A).