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Flashcards in Catalysts Deck (7)
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1

Catalysts

Change rate of chemical reaction without undergoing permanent change itself
Not used up in reaction
May react to form intermediate, or provide surface on which reaction takes place
Catalyst regenerated
Provides alternative pathway, lower activation energy

2

Homogenous catalyst

Same physical state as reactant
Reacts to form intermediate, breaks down, gives product, regenerated

3

Heterogenous catalyst

Different physical state from reactants
Usually solid in contact with gaseous reactants or in solution
Reactant molecules adsorbed onto catalyst surface, reaction takes place
After reaction, product leaves catalyst surface by desorption

4

Industrial processes that use heterogenous catalysts

Haber process N2+ 3H2 <=> 2NH3
Reforming C6H14 => C6H12 + H2
Hydrogenation of alkenes C2H4 + H2 => C2H6
Contact process 2SO2 +O2 <=> 2SO3

5

Heterogenous catalysts and pollution

Catalytic converters, platinum, rhodium, palladium on honeycomb mesh, LSA for reactions
Hot exhaust fumes passed over catalyst, harmful gases converted into less harmful products
CO, NO, Hydrocarbons changed into N2, CO2, H2O

6

Catalysts, sustainability and economic importance

90% of all chemical materials produced w catalyst
Reduces temperature needed, lower AE
Reduces fuel costs, increase profitability
Advantages outweigh costs associated with development of catalyst process
Fewer fossil fuels, reduce CO2 emissions

7

Autocatalysis

Product acts as catalyst for reaction
Reaction starts slowly, no catalyst
Speeds up r of r after cat produced