Porous Solids

Question 1

Define a pore

Answer 1

A minute interstice between particles of matter esp. in soil or rock; A minute hole or channel in a surface, fabric, natural or artificial membrane

Question 2

Draw a diagram of the topology of porous solids

Answer 2

Slide 4

Question 3

What are the two origins of porosity

Answer 3

Intrinsic or synthesised

Question 4

What are 7 pore properties

Answer 4

• Capacity
• Geometry
• Location
• Connectivity
• Tortuosity
• Surface structure
• Surface chemistry

Question 5

What is the fractional porosity

Answer 5

vol pores/external volume of particle

Question 6

What is specific pore volume

Answer 6

Vol pores/mass of solid

Question 7

How would you measure the diameter of an irregular pore?

Answer 7

Take the volume of the pore and use the equivalent diameter as if it were a sphere

Question 8

What are the three classifications of pore size according to IUPAC
Draw diagrams and explain interactions and descibe which model best describes each

Answer 8

Macro - >50nm
Adsorbate - adsorbent interactions mainly
Langmuir - Brunauer
BET

Meso - >2nm
Adsorbate - adsorbate interactions
Kelvin

Micro - < 2nm
Overlap of adsorption forces from sides
dubinin

Question 9

What does location of a pore refer to

Answer 9

Spatial distribution of pores

Question 10

What are the three specifications of locations of pores

Answer 10

Homogenously - distibuted around the whole solid randomly
Heterogenously - clustered together in regions of the solid
Anisotropically - clear ordered orientation

Question 11

What is the measure of connectivity

Answer 11

how many nearest neighbour pores it is connected to compared to how many it could be connected to

Question 12

What is percolation

Answer 12

Where there is a connected channel all the way through the solid

Question 13

How is tortuosity defined

Answer 13

the actual length of a pore through the solid divided by the length of the length if it was a straight line
often rt3

Question 14

In models what length is defined in a pressure drop across a tortuous pore

Answer 14

the length of the pore itself not the straight line length

Question 15

Surface structure of a pore can be split into 4 descriptions, what are they

Answer 15

rough
Smooth
Undulating - wavy
stepped

Question 16

What is surface chemistry

Answer 16

It is the functional groups on the adsorbent

Question 17

How can a pore be characterised

Answer 17

Microscopy (optical, electron)
Radiation scattering (x-rays neutrons)
Fluid penetration (prosimetry)
Fluid flow (permeametry, diffusivity)
Pore contrast method 
Surface chemical analysis 
Adsorption