Hydrogenation is the general process to treat with hydrogen which is a chemical reaction between molecular hydrogen (H
2
​
) and another compound or element, usually in the presence of a catalyst such as nickel, palladium or platinum. The process is commonly employed to reduce or saturate organic compounds.

In the hydrogenation of oils, the catalyst used is Nickel.

Explanation:
Hydrogenation is a chemical reaction in which hydrogen gas (H2) is added to a compound, typically an unsaturated hydrocarbon, resulting in the formation of a saturated compound. This process is commonly used in the food industry to convert liquid vegetable oils into solid or semi-solid fats, which are more desirable for various food applications.

The hydrogenation of oils is carried out in the presence of a catalyst, which speeds up the reaction without being consumed. Nickel is widely used as the catalyst in the hydrogenation of oils due to its effectiveness and cost efficiency.

Here are the reasons why Nickel is the preferred catalyst for the hydrogenation of oils:

1. Catalytic Activity: Nickel exhibits high catalytic activity for the hydrogenation reaction. It has the ability to adsorb hydrogen atoms onto its surface and facilitate their addition to the unsaturated bonds present in the oil molecules. This leads to the saturation of these bonds and the conversion of unsaturated fats to saturated fats.

2. Selectivity: Nickel catalysts are highly selective towards the hydrogenation of carbon-carbon double bonds, which are the primary unsaturated bonds present in vegetable oils. This selectivity ensures that the desired reaction occurs efficiently, without affecting other functional groups or causing unwanted side reactions.

3. Stability: Nickel catalysts are stable and can withstand the harsh reaction conditions required for the hydrogenation process, such as high temperatures and pressures. They do not undergo significant changes in their structure or activity during the reaction, making them suitable for industrial-scale applications.

4. Availability: Nickel is an abundant and relatively inexpensive metal, making it commercially viable for large-scale production. Its availability contributes to the cost-effectiveness of the hydrogenation process and its widespread use in the food industry.

Overall, Nickel is the catalyst of choice for the hydrogenation of oils due to its high catalytic activity, selectivity, stability, and availability. It plays a crucial role in converting liquid vegetable oils into solid or semi-solid fats, which are essential ingredients in various food products.