Promoter (catalysis)

A promoter is a substance that preserves or increases the activity of a catalyst . The distinction to other catalysis terms such as activator , co-catalyst or support material is often not sharp.

Types of Promoters

The mode of action of promoters is diverse. Promoters can serve , for example, to increase the dispersion of the active component of a heterogeneous catalyst on a support. Promoters that influence the structure of the active component are called structural promoters; depending on the mass fraction of the promoter, this is referred to as support material, mixed catalyst or doping.

Promoters can stabilize the carrier material against sintering or increase the strength of the bond between the active component and the carrier. Some promoters increase the tendency of the active component to form alloys. Electronic promoters change the electron density at the reaction site.

Examples

The heterogeneous iron catalyst used in ammonia synthesis is reinforced by oxidic promoters that were added to the magnetite beforehand. In the case of ammonia synthesis, these include, for example, aluminum oxide , potassium oxide , calcium oxide and magnesium oxide .

Alkali metals, especially potassium, are known essential promoters for iron catalysts used in the Fischer-Tropsch synthesis . The effect of platinum metal promoters in cobalt-based Fischer-Tropsch catalysts is based, among other things, on reducing the reduction temperature of cobalt oxide species.

literature

Dirk Steinborn : Fundamentals of organometallic complex catalysis. Vieweg + Teubner, 2007, ISBN 978-3-8351-0088-6 .
Gerhard Ertl , Helmut Knözinger , Ferdi Schüth , Jens Weitkamp : Handbook of Heterogeneous Catalysis. Wiley-VCH, Weinheim 2008, ISBN 978-3-527-31241-2 .

Individual evidence

↑ JJ Spivey, KM Dooley: Catalysis , Vol. 19, RCS Publishing, 2006, ISBN 978-0-85404-239-5 , pp. 10-19.
↑ Alwin Mittasch: Comments on catalysis. In: Reports of the German Chemical Society (A and B Series). 59, 1926, pp. 13-36. doi: 10.1002 / cber.19260590103
↑ Dragomir B. Bukur, Doble Mukesh, Snehal A. Patel: Promoter effects on precipitated iron catalysts for Fischer-Tropsch synthesis. In: Industrial & Engineering Chemistry Research. 29, 1990, pp. 194-204, doi : 10.1021 / ie00098a008 .
^ Gary Jacobs, Tapan K Das, Yongqing Zhang, Jinlin Li, Guillaume Racoillet, Burtron H Davis: Fischer – Tropsch synthesis: support, loading, and promoter effects on the reducibility of cobalt catalysts. In: Applied Catalysis A: General. 233, 2002, pp. 263-281, doi : 10.1016 / S0926-860X (02) 00195-3 .

[spivey-1] JJ Spivey, KM Dooley: Catalysis , Vol. 19, RCS Publishing, 2006, ISBN 978-0-85404-239-5 , pp. 10-19.

[mittasch-2] Alwin Mittasch: Comments on catalysis. In: Reports of the German Chemical Society (A and B Series). 59, 1926, pp. 13-36. doi: 10.1002 / cber.19260590103

[3] Dragomir B. Bukur, Doble Mukesh, Snehal A. Patel: Promoter effects on precipitated iron catalysts for Fischer-Tropsch synthesis. In: Industrial & Engineering Chemistry Research. 29, 1990, pp. 194-204, doi : 10.1021 / ie00098a008 .

[4] Gary Jacobs, Tapan K Das, Yongqing Zhang, Jinlin Li, Guillaume Racoillet, Burtron H Davis: Fischer – Tropsch synthesis: support, loading, and promoter effects on the reducibility of cobalt catalysts. In: Applied Catalysis A: General. 233, 2002, pp. 263-281, doi : 10.1016 / S0926-860X (02) 00195-3 .