Transition metal catalysts are substances that speed up chemical reactions without being consumed in the process. They are typically made from elements found in the d-block of the periodic table, such as iron, copper, and platinum. These metals can easily change their oxidation states, allowing them to facilitate various reactions, including hydrogenation and oxidation. These catalysts are widely used in industrial processes, such as the production of ammonia through the Haber process and in the synthesis of pharmaceuticals. Their ability to provide specific reaction pathways makes them essential for improving efficiency and selectivity in chemical manufacturing.