Hydrogenation process is addition reaction to convert alkene becomes alkane. It converts unsaturated compound to saturated compound.
Ethene reacts with H2 at 180 °C in the presence of nickel or platinum catalyst to produce ethane
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Application of hydrogenation: Making Margarine
Vegetable oils often contain high proportions of polyunsaturated and mono-unsaturated fats (oils), and as a result are liquids at room temperature. That makes them messy to spread on your bread or toast, and inconvenient for some baking purposes.
You can "harden" (raise the melting point of) the oil by hydrogenating it in the presence of a nickel catalyst. Conditions (like the precise temperature, or the length of time the hydrogen is passed through the oil) are carefully controlled so that some, but not necessarily all, of the carbon-carbon double bonds are hydrogenated. This produces a "partially hydrogenated oil" or "partially hydrogenated fat".