Decarbonisation Technology - November 2023 Issue

Temperature swing adsorption

Pressure swing adsorption

Adsorption Nitrogen rich euent

Regeneration

Adsorption

Regeneration

Heater

N rich gas

Flue gas

Blower/ compressor

Recycle b lower

Increase temperature

Reduuce pressure

Cooler

Flue gas

CO rich gas

Pressure swing adsorbents: Carbon-based adsorbents

Temperature swing adsorbents:

Rotating solid beds Amines in composite polymer/silica hollow bres

Zeolite-based adsorbents

Metal-organic frameworks (MOF) - based adsorbents Alkali metal carbonate-based adsorbents Layered double hydroxide (LDH) - based adsorbents CaO-based adsorbents

Alkali ceramic-based adsorbents

Figure 3 Temperature and pressure swing adsorption systems

Membrane-based carbon capture Membrane-based carbon capture uses semi- permeable membranes to selectively separate the CO₂ from the other gases that are present. Depending on what the other gases are, the CO₂ may pass through the membrane, or the other gases might pass through the membrane, leaving the CO₂ behind. A wide variety of membranes are available, and a few of these

contains many small pores that allow the CO₂ to accumulate in the adsorbent. Most solid adsorbent systems use multiple adsorbent beds that can be switched from adsorbing the CO₂ to regenerating the CO₂ out of the adsorbent. This regeneration can be done using a temperature or pressure change, depending on the type of adsorbent being used (see Figure 3 ).

Membrane 1

Membrane 2

Membrane 1

Membrane 2

Feed

Retentate

Feed

Interstage compressor

Feed compressor

Permeate

Vacuum pump

Recycle

Membrane 1

Retentate

Feed

Membrane 2

Feed compressor

Permeate

Vacuum pump

E-33

Compressor

Vacuum pump

Ceramic membranes Supported liquid membranes Metalic membranes

Zeolite etc. Adsorbent membranes

Polymeric membranes

Polyamide - Air Liquide Medal™ APCI Prism Membrane™ UOP Polysep™

Figure 4 Types of membranes and four typical membrane configurations