Alberto Martinez

Question 1

What methods could be used to identify which of the five metals gives rise to the highest catalytic activity?

Answer 1

• BEP

- Sabatier

Question 2

Sabatier principle

Answer 2

• Interaction energy between reactants i.e. molecule and surface, should neither be to strong nor to stable
• Strong interaction leads to very stable situation blocking active site
• Weak interaction molecule fails to bind with the catalyst

Question 3

BEP principle

Answer 3

• Activation energy between two reactions of the same family is proportional to the difference of their enthalpy of reaction
• Slope of BEP trend (a) gives info on TS
• low value, TS resembles the reactant
• high value, TS resembles the product

Question 4

Stress and strain on overlap

Answer 4

• Stress and strain of absorbents affects the overlap of the orbitals between atoms and therefore affects the electronic properties
• To maintain the filling degree, the centre of the band moves upwards in energy

Question 5

Three experiment simulations

Answer 5

• Batch reactor
• Flow reactor
• TPD/TPR/TPA

Question 6

Position of d band

Answer 6

-The lower the d band from the fermi energy, the more occupied the d-states

Question 7

Strength of bond in terms of band centre

Answer 7

The higher the band centre (smaller E(bc)-E(f)) results in stronger bonding

Question 8

Bonding of adsorbate and metal

Answer 8

• Forms a bonding and antibonding orbital
• If orbital interacting already has two e, these are placed in the bonding orbital
• In principle in a molecular case there will be two electrons in the antibonding
• If antibonding lies above the fermi energy, electrons decay into band below fermi level (attractive)
• If antibonding below fermi level it will be filled (No interaction)
• If the interacting orbital is empty, electrons will come from fermi level to fill bonding (attractive)

Question 9

Chemisorption

Answer 9

-Process involves a certain degree of geometry and electron structure distortion

Question 10

Physisorption

Answer 10

-Process is commonly weak and distortion on the structure is negligible

Question 11

Characterisation

Answer 11

• Vibrations: IR and Raman
• Charge density difference
• Work function
• Radial distribution function