Which of the following catalytic systems is used for the reduction of unsaturated hydrocarbon to saturated hydrocarbon? (a) Copper and H2 (b) Iron and H2 (c) Zinc and H2 (d) Nickel and H2

Unsaturated hydrocarbons, such as alkenes and alkynes, can be converted into saturated hydrocarbons (alkanes) through a process known as catalytic hydrogenation [1]. This reaction involves the addition of hydrogen gas (H2) across the carbon-carbon double or triple bonds. For this reaction to proceed at a viable rate, a metal catalyst is required to weaken the H-H and pi bonds [2]. Nickel (Ni) is the most commonly used industrial catalyst for this purpose, particularly in the hydrogenation of vegetable oils to produce solid fats like margarine [3]. While other noble metals like palladium (Pd) and platinum (Pt) are also highly effective catalysts for this reduction, nickel is frequently preferred due to its cost-effectiveness and industrial viability [1]. Copper, iron, and zinc are not standard catalysts for the direct hydrogenation of unsaturated hydrocarbons to saturated ones [1].

Sources

1. [1] Science , class X (NCERT 2025 ed.) > Chapter 4: Carbon and its Compounds > 4.3.3 Addition Reaction > p. 71
2. [2] https://en.wikipedia.org/wiki/Raney_nickel
3. [3] https://www.sciencedirect.com/science/article/abs/pii/S0926860X08007989