Heterogeneous catalysis

Heterogeneous catalysis accelerates a chemical reaction when catalyst and reactants occupy different phases, commonly when gases or liquids react on a solid surface.

Catalyst poisoning: Catalyst poisoning is the loss of catalytic activity when substances bind to or alter active sites. Strongly bound contaminants block the surface sites needed for reactant conversion.
Active site: An active site is a localized region of a catalyst where chemical transformation occurs. Only particular surface locations may bind and convert the reactants efficiently.
Haber–Bosch process: The Haber–Bosch process synthesizes ammonia from nitrogen and hydrogen using an iron-based catalyst. It is a landmark industrial example of gas reactants reacting on a solid catalyst.
Homogeneous catalysis: Homogeneous catalysis occurs when catalyst and reactants occupy the same phase. It contrasts with reactions at an interface between catalyst and reactants.
Single-atom catalysis: Single-atom catalysis uses isolated metal atoms anchored to a support as catalytic sites. It tests whether maximizing atom utilization can preserve activity and selectivity.
Adsorption: Adsorption is the accumulation of atoms, ions, or molecules at the surface of a solid or liquid. Reactants commonly attach to catalyst surfaces before reacting.
Chemisorption: Chemisorption is adsorption involving chemical-bond formation between an adsorbate and a surface. Chemical bonding to the surface can activate reactants for subsequent steps.
Contact process: The Contact process manufactures sulfuric acid, including catalytic oxidation of sulfur dioxide over vanadium(V) oxide. Its gas-phase oxidation step occurs on a solid catalyst.
Enzyme catalysis: Enzyme catalysis is the acceleration of biochemical reactions by biological macromolecules, usually proteins or RNA. Enzymes typically bind substrates in molecular active sites rather than on extended solid surfaces.
Metal–organic frameworks: Metal–organic frameworks are porous crystalline materials built from metal nodes linked by organic molecules. Their tunable pores and sites offer ways to control catalytic environments.

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