AdvancedTopic 85 of 100Materials & Chemical
Catalysis
Catalysts lower activation energy and increase selectivity.
In depth
Catalysts lower activation energy to speed reactions and improve selectivity without being consumed; homogeneous (same phase) or heterogeneous (solid in fluid) or enzymatic. Metrics: turnover frequency, activity, selectivity, stability. Deactivation by poisoning, sintering or coking.
Key points
- Active sites
- Promoters and supports
- Haber-Bosch iron catalyst
ExampleCatalytic converters use Pt/Pd/Rh to oxidise CO and reduce NOx.
What is Catalysis?
Catalysts lower activation energy and increase selectivity.
Why is it important to understand catalysis?
Catalysts speed reactions and direct them towards the desired product, which improves both economy and energy use in chemical plants.
Does a catalyst change the equilibrium?
No. It changes the rate at which equilibrium is reached, but the equilibrium composition stays the same.
What is selectivity?
The fraction of converted reactant that forms the desired product, which is important for yield and waste.
How is Catalysis used in practice?
Typical applications include using a platinum catalyst in a catalytic converter to oxidise pollutants, selecting a catalyst for ammonia synthesis to reduce the required temperature and choosing a catalyst that favours one isomer over another.
What should I learn before Catalysis?
Study "Reactor design equations" first (topic 84 of 100 in Materials & Chemical). It covers the groundwork this topic builds on.
What are the key points of Catalysis?
Active sites. Promoters and supports. Haber-Bosch iron catalyst.
Can you give an example of Catalysis?
Catalytic converters use Pt/Pd/Rh to oxidise CO and reduce NOx.
What comes after Catalysis?
The next topic is "Heterogeneous catalysis", which builds directly on this one.
How difficult is Catalysis?
It is classed as Advanced in Materials & Chemical (topic 85 of 100). It is an advanced topic. It assumes you are comfortable with the intermediate topics in Materials & Chemical.