Today, most chemical processes are catalytically assisted: catalysts accelerate reactions, or make them possible in the first place, without being consumed in the process. In heterogeneous catalysis, the catalyst and the reactants exist in different “phases,” as chemists say that is, in different physical states.
The catalyst is often solid, such as in an automotive catalytic converter, while the reactants, gases or liquids, flow past it and are triggered into reaction through contact. Compared to homogeneous catalysis, heterogeneous catalysis offers advantages: reactants and products are easier to separate, and the catalyst can be more easily regenerated.
The term catalysis was coined in the 19th century by Jöns Jakob Berzelius, who observed similarities in very different chemical reactions for example, the dehydrogenation of alcohols to aldehydes on glowing metals, or the breakdown of ethanol into ethylene and water over alumina. In these cases, alongside the reactants and products, there is always a third substance involved one that appears to remain unchanged.
A classic example is ammonia synthesis, developed just over 100 years ago. It revolutionized global food supply at a time when natural sources of nitrogen fertilizer (such as saltpeter) were becoming scarce. The Haber-Bosch process extracts nitrogen from the air by “cracking” molecular nitrogen (N₂), a form unusable by most plants, using hydrogen and an iron catalyst.
Today, heterogeneous catalysis plays a vital role in tasks like converting carbon dioxide from the atmosphere into useful chemical products essentially turning a climate threat into a valuable feedstock. These developments are gradually replacing fossil-based raw materials like coal, oil, and gas, laying the foundation for a greener chemical industry based on renewable energy and sustainable resources.
Further Links
Heterogeneous Catalytic Process Development at the Leibniz Institute for Catalysis
Catalyst Development and Reaction Engineering at the Leibniz Institute for Catalysis
Heterogeneous Photocatalysis at the Leibniz Institute for Catalysis
Want to learn more?
A comprehensive introduction to key concepts is available here:
Operando Research in Heterogeneous Catalysis