Process simulation for electronic-grade methanethiol synthesis via H₂S recovery from Rectisol Tail Gas

College of Chemistry and Chemical Engineering, Xi’an University of Science and Technology, Xi’an 710054, China

^* wangghxust@xust.edu.cn

Abstract

This study proposes an integrated process for producing electronic-grade methanethiol (EMT) from H₂S-rich Rectisol tail gas (RTS) through three stages: H₂S purification, methanethiol (MT) synthesis, and MT refining. First, a two-stage methyl diethanolamine absorption-desorption process selectively recovers H₂S from RTS, achieving 92 mol% H₂S purity. Subsequently, MT is synthesized via methanol and H₂S over a K₂WO₄/Al₂O₃ catalyst in a fixed-bed reactor optimized at 380°C, 10 bar, and a mass hourly space velocity (MHSV) of 2 h⁻¹, achieving 90% methanol conversion and 92% MT selectivity. Finally, the crude product is separated via a optimized distillation sequence, with a pressure-swing distillation to break the methanol-dimethyl sulfide azeotrope, yielding EMT with 99.99 wt% purity. Rigorous Aspen Plus simulations demonstrate the process's economic viability, leveraging H₂S valorization to produce high-value EMT while meeting stringent emission standards (<0.03 mg/m³ H₂S).