Understanding Sulfur Content in Alkylate from Sulfuric Acid-Catalyzed C3/C4 Alkylations
- David L. MinnickDavid L. MinnickDepartment of Chemical & Petroleum Engineering and Center for Environmentally Beneficial Catalysis, University of Kansas, Lawrence, Kansas 66045, United StatesMore by David L. Minnick,
- Rajkumar R. KoreRajkumar R. KoreDepartment of Chemical & Petroleum Engineering and Center for Environmentally Beneficial Catalysis, University of Kansas, Lawrence, Kansas 66045, United StatesMore by Rajkumar R. Kore,
- Christopher J. LyonChristopher J. LyonDepartment of Chemical & Petroleum Engineering and Center for Environmentally Beneficial Catalysis, University of Kansas, Lawrence, Kansas 66045, United StatesMore by Christopher J. Lyon,
- Bala SubramaniamBala SubramaniamDepartment of Chemical & Petroleum Engineering and Center for Environmentally Beneficial Catalysis, University of Kansas, Lawrence, Kansas 66045, United StatesMore by Bala Subramaniam,
- Mark B. ShiflettMark B. ShiflettDepartment of Chemical & Petroleum Engineering and Center for Environmentally Beneficial Catalysis, University of Kansas, Lawrence, Kansas 66045, United StatesMore by Mark B. Shiflett, and
- Aaron M. Scurto*Aaron M. Scurto*Email: [email protected]. Phone: +1 (785) 864-4947Department of Chemical & Petroleum Engineering and Center for Environmentally Beneficial Catalysis, University of Kansas, Lawrence, Kansas 66045, United StatesMore by Aaron M. Scurto
Abstract
Alkylation of short-chain olefins with isobutane catalyzed by sulfuric acid is a common process for reformulated fuel. Here, pilot-plant and commercial C3 and C4 alkylates were examined for sulfur content, acid content, and emulsion formation. Even though the thermodynamic solubility of sulfuric acid in alkylate is negligible at process conditions, the C4 alkylate samples contained ∼20 ppm sulfur mostly from very dilute emulsions with ∼3 μm droplets of sulfuric acid and alkyl sulfates that were stable even after 6 months. The sulfur content and droplet size increased for propylene alkylation. However, no detectable emulsion or sulfur content could be generated synthetically by intense mixing with either 2,2,4-trimethylpentane (a model alkylate) or a treated pilot-plant alkylate with concentrated or spent sulfuric acid over the course of several hours. Thus, the alkylate sulfur content is most likely created during the acid-catalyzed chemical reaction steps and not from high-shear mixing.