Insights into Specific Surface Area Assessed by Inverse Gas Chromatography and Manometric Gas Adsorption: A...

Area of Science:

• Physical Chemistry
• Materials Science
• Surface Science

Background:

• Surface area (SSA) is a critical material property.
• Standard methods like Brunauer-Emmett-Teller (BET) and manometric gas adsorption (MGA) are widely used.
• Inverse gas chromatography (IGC) offers a potential alternative or complementary technique.

Purpose of the Study:

• To critically compare SSA determination using IGC and MGA.
• To evaluate IGC's reliability as a complementary tool to BET.
• To investigate the limitations of current SSA assessment methods, particularly the fixed molecular area assumption.

Main Methods:

• Analysis of 73 literature data pairs comparing IGC and MGA.
• Utilized n-alkanes as probe molecules in IGC.
• Focused on macro-mesoporous materials and solids with narrow mesopores or micropores.

Main Results:

• IGC results are qualitatively and quantitatively consistent with MGA for macro-mesoporous materials (SSA < 150 m² g⁻¹).
• Increased variability in IGC results was observed for solids with narrow mesopores or micropores.
• A fundamental flaw in the fixed molecular area assumption was identified, impacting SSA values.

Conclusions:

• IGC is a valuable complementary tool to MGA and BET for macro-mesoporous materials.
• Further studies are needed to establish IGC reliability for complex pore structures (micropores/narrow mesopores).
• SSA values are apparent, not intrinsic, and depend on probe molecule's temperature-dependent effective area.