What is the most common metal catalyst in hydrogenation?

Related questions

• What is hydrogenation of alkenes?
• Why does hydrogenation require a catalyst?
• How can I explain the mechanism for catalytic hydrogenation?
• Is the addition of hydrogen to a compound a reduction reaction? Why?
• What is the heat of hydrogenation in a hydrogenation reaction?
• Why do the most stable alkenes have the smallest heat of hydrogenation?
• How many different alkenes can be hydrogenated to form butane?
• How many different alkenes can be hydrogenated to form 3-methylpentane?
• How many different alkenes can be hydrogenated to form hexane?
• What alkene would you start with if you wanted to synthesize pentane?