Hydrogen sulfide is produced on a large scale as industry waste. It is toxic, corrodes equipment, poisons catalysts, and requires energy-intensive removal. Conventional gas-phase desulfurization relies on the Claus process, which yields low-value sulfur and water:

H₂S + 1/2 O₂ → 1/8 S₈ + H₂O.

Researchers have explored the direct decomposition of H₂S through the generation of hydrogen gas, but these approaches are limited by unfavorable thermodynamics.

Yongan Yang and colleagues, Colorado School of Mines, Golden, USA, have devised a method for H₂S removal based on a thermodynamically favorable reaction. Specifically, sodium naphthalenide (NaC₁₀H₈) is used to transform H₂S into anhydrous Na₂S nanocrystals while recovering hydrogen to form 1,4-dihydronaphthalene (C₁₀H₁₀):

2 NaC₁₀H₈ + H₂S → Na₂S + C₁₀H₁₀ + C₁₀H₈.

The two value-added products are used as battery materials and liquid fuels, respectively. The generated naphthalene (C₁₀H₈) can easily be recycled.

This process is driven by the acid/base reaction between protons from H₂S and radical anions from naphthalenide. The reaction is spontaneous and irreversible at ambient temperature and pressure, and H₂S is rapidly removed to below detection limits. This chemistry is expected to be quite flexible, and work is underway developing alternative reagents to direct the conversion of H₂S into other value-added products.

---

• Thermodynamically Favorable Conversion of Hydrogen Sulfide into Valuable Products through Reaction with Sodium Naphthalenide,
  Xuemin Li, Rachel M. Morrish, Yuan Yang, Colin A. Wolden, Yongan Yang,
  ChemPlusChem 2015.
  DOI: 10.1002/cplu.201500299