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HPM > Lecture 1 > Flashcards

Lecture 1 Flashcards

1
Q

What are the Highly Porous Materials?

A

Substances characterized by having a large number of pores or void spaces within their surface area.

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2
Q

Mention characteristics of the pores

A

These pores can vary in size, shape and distribution; but they are typically small relative to the overall size of the material.

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3
Q

Where can be found porous materials?

A

Porous materials can be found in various forms, including:
- Solids
- Liquids
- Gases

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4
Q

Areas of application of highly porous materials

A
  • Catalysis
  • Adsorption
  • Gas storage
  • Sensor technology
  • Cromatography
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5
Q

SOLIDS
Porous solids

A

Materials like carbon, silica gel, zeolites and metal-organic frameworks (MOFs).

They have a network of interconnected pores that provide a large surface area, making them useful as:
- Adsorption
- Filtration
- Catalysis

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6
Q

SOLIDS
Porous Ceramics

A

Ceramics engineered to have high porosity, often used for their lightweight, insulating filtering properties.

  • Alumina: with controlled porosity are used in: thermal insulation, membrane support and catalyst support.
  • Silicon carbide: used in applications requiring high thermal conductivity, chemical resistance and mechanical strength, such as: filters for hot gas filtration.
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7
Q

LIQUIDS
Aerogels

A

Lightweight materials derived from gels where the liquid component has been replaced with gas, resulting in a highly porous structure.

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8
Q

GAS
Foams

A

Materials consisting of gas bubbles trapped within a solid or liquid matrix, resulting in a porous structure.

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9
Q

Highly materials common feature

A

Interaction between: molecule <———> Solid surface

Solid material should have a large specific surface area:

  1. Textural porosity: breaking up of a particle into smaller pieces
  2. Structural porosity: Drilling in the particle
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10
Q

How can be porosity classified?

A

Textural
Structural

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11
Q

Motivation for the use of Porous Materials

A
  1. Field of application: insulation material for thermal insulation
  2. Principal property: supression of heat conduction by discontinuities (ex: pores in the solid matrix)
  3. Ideal case: Closed cavities without gas exchange with the environment and thus without heat transport by convection
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12
Q

Name 3 commercial known (or examples) of porous materials

A

Z.b:
Zeolite
Activated carbon
Silica gel

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13
Q

PORE SYSTEMS:

How is divided the Structural Porosity?

A

Pores in particles, specific surface area stems from the surface area of the pore walls.

It is divided into: open porosity and closed porosity

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14
Q

According to the width: how can be classified the porous?

A

One value: Zeolite
Narrow range: Activated carbon
Width range: Silica gel

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15
Q

PORES SYSTEMS - Structural porosity

What is the classification of Open Porosity?

A
  1. Micropores: <2 nm width ; very high surface area ; strong interaction with molecules ; poor mass transport
  2. Mesopores: 2 - 50 nm width (Silica gel)
  3. Macropores: > 50 nm width ; small surface area ; very good mass transport
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16
Q

Mentioned the 2 ways that porosity can be generated?

A
  1. Breaking up of a particle into
    smaller pieces
    (textural porosity).
  2. Drilling in the particle
    (structural porosity).
17
Q

Name the 3 principles of synthesis of P.M

A

Aggregation
Substraction
Recrystallisation

18
Q

What is sintering?

A

Sinterizar: Producir piezas de gran resistencia y dureza, calentando, sin fundir, conglomerados de polvo modelador por presión

19
Q

Which two processes reinforce the “aggregation”?

A

Drying and Sintering

20
Q

Explain Aggregation as a principle of the synthesis of PM

A
  • Starting with finely dispersed,
    non-porous particles.
  • Agglomeration.
  • Drying and sintering that produces solidification of the
    microstructure.
21
Q

Name two types/procedures of substraction in PM

A

Dissolving
Oxidising

22
Q

Name a moment when the “Recrystallisation” is used:

A

In the Zeolite synthesis through an Amorphous precipitation

23
Q

Are micropores, when compared to macropores, suitable for mass transport?

A

No, micropores are characterized for having poor mass transport characteristics

24
Q

Explain Substraction as a principle of the synthesis of PM

A

Removal of components from non-porous or porous macroscopic particles of inhomogeneous
composition by dissolving, oxidising and other processes.

25
Q

Explain Recrystallisation as a principle of the synthesis of PM

A

Precipitation of amorphous precipitates, through post-treatment (e.g. hydrothermal ) formation of
complete or partially crystalline products.

26
Q

Which is the common feature of all the applications of HPM?

A

The focus is always on the interaction between molecules and the surface of a solid

27
Q

5 g of Zeolite may have an internal surface area of

A

Almost a football field: 5000- 6000 m2

28
Q

Particles of nanometre range are difficult to handle. What can be done to tackle this issue, regarding to HPM?

A

Create the pores in the material itself. Structural porosity.

29
Q

HPM are used as insulating thermal materials. BUT, what does it mean?

A

Supress heat conduction by discontinuities

30
Q

Closed porosity, which belongs to structural porosity, should we take it into account? Why?

A

No, ´cause the pdf, AI voice and script says so

31
Q

Is Activated carbon usually: Micro, meso or macro porous? Unique, narrow or wide pore distribution?

A

Microporous.
Distribution is wider than Zeolite.
Pore width is narrower than Zeolite

32
Q

Is Silica gel: Micro, meso or macro porous? Unique, narrow or wide pore distribution?

A

Mesoporous and broad pore width distribution

33
Q

How is tipcally presented the silica gel? Powder, granulate, liquid, gas…?

A

Powder or Granulate

34
Q
A

HPM (3 decks)

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