The correct option is Nickel.
Explanation
Hydrogenation is an industrial chemical process used to convert unsaturated hydrocarbons (containing double bonds) into saturated hydrocarbons (single bonds) by the addition of hydrogen. In the food industry, this process transforms liquid vegetable oils into semi-solid or solid fats (such as vegetable ghee or vanaspati).
Detailed Analysis
- Role of the Catalyst: The reaction between hydrogen gas and vegetable oil is slow. A catalyst is required to increase the rate of reaction by providing a surface for the adsorption of reactants.
- Nickel (Ni): Finely divided Nickel is the most commonly used catalyst in the industrial hydrogenation of oils. It is preferred because it is highly effective at the required operating temperatures and is significantly more cost-effective than noble metals.
- Palladium (Pd) and Platinum (Pt): While these metals are excellent hydrogenation catalysts and can work at lower temperatures, their high cost makes them economically unviable for large-scale industrial food processing. They are typically reserved for laboratory synthesis or high-value pharmaceutical applications.
- Copper (Cu): Copper is generally not used as a primary catalyst for the hardening of fats, although copper-chromite catalysts exist for other specific hydrogenation reactions.
Key Takeaway: Finely divided Nickel is the standard catalyst used in the industrial hydrogenation of vegetable oils to produce vegetable ghee (vanaspati) due to its catalytic efficiency and economic viability.