Feedstock Matters
In one main production route, hydrogen sulfide (H2S) reacts with methanol to make dimethyl sulfide (DMS), which is then oxidized to DMSO. The source of H2S determines the purity ceiling of the entire downstream chain.
Purity and Impurities
Refinery or Fertilizer H2S
As an environmental byproduct, the stream carries CO2, H2, N2, methane, and even trace CO and HCN. CO2 and CO poison the methanol-synthesis catalyst. Amine absorption, decarbonization, and hydrocarbon removal are required to clean it up.
CS2 Byproduct H2S
CS2 is produced from natural gas plus sulfur; its H2S byproduct is mostly uncontaminated natural gas, trace sulfur vapor, and a small amount of residual CS2. There is hardly any CO2, CO, or cyanide. Condensation and simple adsorption reach 98%+ purity.
Equipment and Cost
Refinery H2S is often cheap because it is an environmental byproduct, but the front-end purification units add capex and maintenance. CS2 byproduct offers vertical integration; in China, DMSO production mainly follows three routes, and the difference is at the feed end. Cost depends on how each company supply chain is set up.
Supply Stability
Refineries and fertilizer plants run steadily as cornerstones of energy and food security, but crude slate changes cause tail-gas volume swings. CS2 producers are market-sensitive; when CS2 prices fall and plants cut output, downstream DMSO can run short. In total volume and long-term continuity, large refineries and fertilizer plants hold up better.
Conclusion
For the high end (electronic-grade cleaning, pharma intermediates), CS2 byproduct H2S delivers the strictest purity specs and avoids quality swings. For high-volume, cost-driven operations (pesticide solvents, general industrial chemicals) with a committed integrated refinery nearby, refinery tail gas is a genuinely competitive route with proper front-end purification.