**3.6. Sulfinol™**

In the Rectisol™ process, the raw syngas is cooled before being introduced into the absorption

that, the sulfur exempt syngas contacts with the chilled methanol in the absorber, operating at 50 atm and temperatures in the range of [−100°C, −30°C]. The rich solvent is then sent to

The Ifpexol™ process introduced in 1991 can be used for natural gas applications. This process is based on two steps as follows: Ifpex-1™ removes condensable hydrocarbons and water and Ifpex-2™ removes acid gas [58]. Ifpexol™ is licensed by Prosernat and uses refrigerated metha-

The Ifpexol-2™ process for acid gas removal is similar to an amine-based chemical absorption process except for the operating temperatures. The absorber operates below −29°C to minimize methanol losses, and the regenerator operates at about 6 bar. Cooling is required on the regenerator condenser to recover the methanol releasing during the regeneration step. This process usually follows the Ifpexol-1™ process so excessive hydrocarbon absorption is not as great a

Fluor™ process is the most suitable physical absorption process to be applied for high CO2

tial pressure syngas streams and has been in use since the late 1950s. Fluor™ is licensed by Fluor

solvent), which has a lower vapor pressure than those used by Rectisol™ and Selexol™. The

In the Fluor™ process, physical absorption occurs at moderate to high-pressure, ranging between 30 and 80 bar, and at ambient temperature. The flue gas must be dehydrated before the gas enters into the absorption column to prevent water build-up in the solvent. As indicated

H6 O3

is released by flash desorption, reducing the pressure up to

loaded solvent. After

par-

removal

is absorbed, the

synthesis gas from

exits the regeneration stages to

) as solvent (available as JEFFSOL™ PC

S and can be applied in large CO2

and recovers its original capacity. The lean solvent

S. This technology is licensed by Lurgi AG

absorption occurs. After CO2

process. The sulfur compounds must be firstly removed using a CO<sup>2</sup>

1 bar. The lean solvent is recycled back to the absorber [2, 57].

Daniel, Inc. and employs propylene carbonate (C4

solvent requires neither a low nor no presence of H2

S must also be removed before the CO2

is recycled back to the absorber, whereas the high purity CO2

The Purisol™ process is particularly suited to treat high-pressure, high CO2

loaded solvent is flashed to release CO<sup>2</sup>

IGCC systems because of the high selectivity for H2

be compressed and stored [62].

and employs N-methyl pyrrolidone.

the regeneration stage where CO2

156 Carbon Dioxide Chemistry, Capture and Oil Recovery

**3.3. Ifpexol™**

problem [59].

**3.4. Fluor™**

before, H2

**3.5. Purisol™**

CO2

applications [60, 61].

nol as physical solvent.

The Sulfinol™ process can remove H<sup>2</sup> S, CO2 , carbonyl sulfide, mercaptans and organic sulfur components from natural and synthesis gas from coal or oil gasifiers and steam reformers. This process accomplishes H2 S and CO2 separation in a wide variety of compositions up to around 50%v/v H<sup>2</sup> S and above 20%v/v CO2 . The principle of this process aims at combining the high absorption potential of alkanolamine (chemical absorption) and the low regeneration energy requirement of the physical solvent (physical absorption).

Sulfinol™ is licensed by Shell Oil Company and employs mixtures of diisopropylamine (DIPA) or methyldiethanolamine (MDEA) and tetrahydrothiophene dioxide (SULFOLANE) in different blends. The physical solvent used (DIPA or MDEA) has a higher absorption capacity and a low energy requirement for regeneration, thus increasing the carrying capacity due to lower solvent recycled requirements. The absorber is operated at 40°C and a pressure around 60–70 bar. The rich solvent is then sent to the stripping column where CO<sup>2</sup> is released at temperatures over 110°C and vacuum pressure. It should be noted that addition of antifoam is needed in the absorber and solvent degrades due to the presence of oxygen and stripper temperatures [64].
