New Carvone-Based Deep Eutectic Solvents for Siloxanes Capture from Biogas

Area of Science:

• Chemical Engineering
• Environmental Science

Background:

• Siloxane deposition (SiO2) during biogas combustion damages engine components, necessitating advanced biogas purification methods.
• Green engineering principles drive the search for biodegradable, non-toxic solvents with high absorption capacity for biogas purification.

Purpose of the Study:

• To investigate Deep Eutectic Solvents (DES) as effective agents for siloxane removal from biogas.
• To identify and synthesize DES with high affinity for siloxanes, focusing on carvone and carboxylic acid combinations.

Main Methods:

• Utilized conductor-like screening models for real solvents (COSMO-RS) to evaluate 90 DESs for siloxane affinity.
• Synthesized promising DES and characterized their physicochemical properties.
• Employed theoretical (σ-profiles) and experimental (NMR, FT-IR) studies to elucidate DES formation and siloxane interaction mechanisms.

Main Results:

• Identified novel DES, specifically those combining carvone and carboxylic acids, exhibiting superior affinity for siloxanes.
• Demonstrated that hydrogen bonds between ketone (=O) and carboxyl (-COOH) groups are crucial for stable DES formation and low melting points.
• Established that non-bonded interactions are key to the effective capture of siloxanes by the synthesized DES.

Conclusions:

• Carvone and carboxylic acid-based DES are highly effective for siloxane removal in biogas purification.
• Understanding the hydrogen bonding and non-bonded interactions is critical for designing efficient DES for siloxane capture.
• This research offers a promising green engineering approach to mitigate biogas engine damage caused by siloxanes.