1. Petrochemical Industry - Aromatics Extraction & Gas Purification

Sulfolane is the dominant solvent in the UOP/Shell Sulfolane extraction process for BTX aromatics (benzene, toluene, xylene) separation from reformed gasoline and cracked naphtha, accounting for over 70% of total global sulfolane consumption. Its aromatics solubility (≥50% at 20°C) and high selectivity deliver final BTX purity above 99.9% - significantly outperforming diethylene glycol ether solvents.

In natural gas and syngas purification, sulfolane efficiently removes H₂S and CO₂. Its regeneration energy consumption is 30% lower than MDEA solvents, making it especially cost-effective for high-sulfur shale gas and coalbed methane fields.

Reference: Honeywell UOP Sulfolane™ Process ↗

2. Electronics & Semiconductor - High-Purity Cleaning Solvent

Electronic-grade sulfolane (metal ions ≤1 ppb) is used for photoresist stripping and semiconductor wafer cleaning, avoiding contamination of precision components and improving chip and LCD/OLED display yields. Its chemical stability and low residue level meet the stringent cleanliness requirements of leading semiconductor fabs.

Reference: The Electrochemical Society (ECS) ↗

3. Lithium Battery Electrolyte Additive

Adding 5–10% sulfolane to lithium-ion battery electrolyte formulations markedly improves high-temperature stability (60°C), extending cycle life by up to 2× and reducing short-circuit risk. Compatible with NMC (ternary) and LFP (lithium iron phosphate) battery chemistries. Electronic Grade purity is mandatory to avoid electrochemical side reactions.

The wide electrochemical stability window of sulfolane also makes it a promising co-solvent for next-generation solid-state and high-voltage battery electrolytes.

Reference: PubChem - Sulfolane (NIH) ↗

4. Fine Chemicals & High-Performance Polymer Processing

As an inert high-boiling reaction solvent (150–250°C) for aromatic alkylation and cyclization (e.g., synthesis of pharma intermediate quinoline), sulfolane does not react with Lewis acid catalysts and reduces by-product generation to below 5%. It is also used as a chlorinated derivative (chlorosulfolane) to synthesize ionic liquids, replacing corrosive strong acids in esterification and nitration.

Sulfolane dissolves high-performance polymers including polyimide (PI) and polyphenylene sulfide (PPS), enabling fabrication of flexible circuit board substrates and high-temperature filter fibers.

5. Coatings, Heat Transfer & Textile Industries

Used as a co-solvent for high-temperature anti-corrosion coatings (silicone resin systems); coating films cured above 200°C pass 1,000+ hour salt spray tests. As a medium-temperature heat transfer fluid (service range 100–250°C), sulfolane offers 15% higher thermal conductivity than mineral oil with annual volatility loss below 1%. In textiles, it improves dye uptake rate and color fastness.

Reference: ECHA REACH Registration ↗

Q: Is sulfolane liquid or solid at room temperature?

Sulfolane's melting point (freezing point) is 27–28°C, so it is a solid just below typical room temperature and becomes a clear colorless liquid above 28°C. Because the melting point is close to ambient, Industrial Grade is often transported as a 3% aqueous solution (sulfolane aqueous) for easier handling. Pure (anhydrous) grades should be handled with mild heating if solidified.

Q: What is the difference between Industrial Grade and Electronic Grade sulfolane?

Industrial Grade (≥99.0%) is used for bulk petrochemical processes with no specific metal ion restriction. Electronic Grade (≥99.99%) requires individual metal impurities below 1 ppb - critical for semiconductor cleaning and lithium battery electrolytes where trace metals degrade performance. Electronic Grade also requires nitrogen-sealed packaging to prevent moisture and contamination.

Q: What is the sulfolane extraction process (UOP Sulfolane Process)?

The UOP Sulfolane extractive distillation / liquid–liquid extraction process uses sulfolane as the selectivity solvent to separate BTX aromatics from non-aromatic hydrocarbons in reformed gasoline. The rich sulfolane phase is stripped to recover pure aromatics; the lean solvent is regenerated and recycled. Shell and Chevron operate similar licensed variants. This process produces the benzene, toluene, and xylene feedstocks used across the petrochemical industry.

Q: Does sulfolane have a formula / chemical structure?

Yes. The molecular formula is C₄H₈O₂S (molecular weight: 120.17 g/mol). The structural formula is O=S(CH₂)₄ - a five-membered saturated ring with one sulfur atom bearing two oxygen atoms. The SMILES notation is O=S1(=O)CCCC1. The cyclic sulfone ring is responsible for sulfolane's high thermal stability and strong polarity.

Q: What are the sulfolane SDS / MSDS details?

Key SDS highlights: GHS Category - slightly hazardous; oral LD₅₀ (rat) 1.54 ml/kg; skin irritation: mild; eye irritation: mild; not classified as carcinogenic. Storage: sealed containers, 5–30°C, away from oxidizers. PPE: gloves, goggles, protective clothing. Emergency: flush skin/eyes with water; induce vomiting if ingested. Full SDS/MSDS PDF available on request from sales@sinolookchem.com.

Q: What is the sulfolane CAS number and HS code?

The CAS number for sulfolane is 126-33-0. The CAS number for sulfolane anhydrous is the same: 126-33-0. The HS Code (Harmonized Tariff Code) for China export is 2930909090. For customs classification assistance, please contact our trade team.

Q: What sulfolane alternatives exist, and when is sulfolane preferred?

Common sulfolane alternatives for aromatic extraction include diethylene glycol (DEG), N-methylpyrrolidone (NMP), and N-formylmorpholine (NFM). Sulfolane is preferred when higher thermal stability, lower solvent losses, and higher aromatic selectivity are required. For battery electrolytes, fluorinated sulfones or DMF may be used but at significantly higher cost. For general polar aprotic applications, DMSO is a lower-boiling alternative but lacks sulfolane's thermal stability and is not suitable for high-temperature processes.