Problem 109 - A Complete Resource Book in Chemistry for JEE Main

Question

The catalyst used in Zeigler process for polyethylene manufacture (a) consists of aluminium triethyl and titanium tetrachloride (b) is vanadium pentoxide (c) consists of aluminium chloride and titanium dioxide (d) is finely divided nickel

Step-by-Step Solution

Answer

The catalyst in the Ziegler process is aluminum triethyl and titanium tetrachloride, so the correct option is (a).

Step 1: Understand the Ziegler Process

The Ziegler process is a method for producing polyethylene using specific catalysts that allow polymerization to occur at lower pressures and temperatures compared to traditional methods.

Step 2: Identify the Catalyst Components

The catalyst used in the Ziegler process typically consists of a combination involving a transition metal compound and an organoaluminum compound. Commonly, this is known to be a mixture of titanium compounds (such as titanium tetrachloride) and trialkylaluminums (such as aluminum triethyl).

Step 3: Analyze the Given Options

Look at the given options to identify which one matches the description of the catalyst used in the Ziegler process. Option (a) is aluminum triethyl and titanium tetrachloride, aligning perfectly with the known Ziegler catalyst components.

Step 4: Select the Correct Option

Based on the correct components for the Ziegler process catalyst identified in Step 2, the correct answer is option (a), aluminum triethyl and titanium tetrachloride.

Key Concepts

Polyethylene Manufacture

Polyethylene is one of the most common plastics found in a wide variety of products. The manufacture of polyethylene involves polymerizing ethylene molecules to form long chains, resulting in this versatile plastic. In traditional methods, it required high pressure and temperature. However, the Ziegler process revolutionized this by enabling the polymerization at much milder conditions.

The Ziegler process employs specific catalysts that effectively break down ethylene molecules, allowing their linkage into the polymer chains. This methodology not only makes the manufacturing process energy efficient but also allows for greater control over the polymer's properties, making it adaptable to a variety of applications, from packaging materials to containers and beyond.

• Provides cost-effectiveness
• Uses lesser energy due to lower temperature and pressure
• Enables customizability of the polymer's characteristics

Titanium Tetrachloride

Titanium tetrachloride is a critical component in the catalyst used in the Ziegler process for the manufacture of polyethylene. This chemical compound of titanium is paired with organoaluminum compounds to create a powerful catalytic mixture.

Titanium tetrachloride, known chemically as TiCl₄, plays a crucial role in the catalyst as it facilitates the polymerization process of ethylene into polyethylene. It helps in controlling the reaction environment by making the active sites on the catalyst available for the monomer attachment.

One of its notable features is its strong interaction with aluminum compounds, which helps create an active catalytic site where polymerization occurs. This interaction ensures consistent production of polyethylene under controlled manufacturing conditions.

• Key component in Ziegler catalysts
• Essential for controlling polymerization reactions
• Works synergistically with organoaluminum compounds

Organoaluminum Compound

Organoaluminum compounds are critical in the Ziegler process. They act alongside transitional metal compounds like titanium tetrachloride to catalyze the polymerization of ethylene into polyethylene.

An example of an organoaluminum compound used is aluminium triethyl. These compounds are notable for their ability to generate reactive sites on the titanium, promoting the effective conversion of ethylene into polyethylene chains.

These compounds are crucial as they help stabilize the reaction environment, facilitating high efficiency in polymerization under milder conditions, which is not as feasible in conventional reactions. Besides their chemical stability, organoaluminum compounds impart flexibility and control over the reaction pace, increasing the overall efficiency and quality of the polyethylene produced.

• Facilitate stabilization and activation of catalysts
• Enable operation under mild conditions
• Enhance efficiency of the polymerization process