LAUSR

Abstract Liquid phase sulfur recovery was explored in a eutectic solvent to demonstrate proof-of-concept for an alternative Claus tail gas cleanup process. A simulated tail gas feed containing 3% H2S and 1.5% SO2 was converted to elemental sulfur within a biphenyl and diphenyl ether eutectic solvent. The formed sulfur accumulates at the bottom of the reactor upon solvent saturation, allowing for liquid–liquid separation if the temperature is maintained above 120 °C. Alternatively, crystallization of elemental sulfur could be performed with lower sulfur solubility in the solvent at room temperature. In the temperature range of 120 – 150 °C, a Claus equilibrium conversion of > 99% was achieved when care was taken to maintain the H2S/SO2 ratio at 2:1. While lower temperature favours Claus equilibrium, destruction of other sulfur containing species such as CS2 often suffers at these lower temperatures. Therefore, CS2 destruction was explored within the eutectic solvent over both alumina and titania catalysts, which are commonly used in commercial applications. Good conversions were observed for both alumina and titania when maintaining the H2S/SO2 ratio at 2:1. Better CS2 conversions of 95% (over alumina) and 98% (over titania) were observed at 150 °C when operating at an H2S/SO2 ratio at 2.3:1. The total sulfur conversions, when assuming theoretical equilibrium conversion in the sulfur recovery unit, combined with the liquid-phase tail gas cleanup process ranged from 99.3 to 99.9%. Addition of water to the feed negatively affected the CS2 destruction on titania but had little effect on alumina. At sulfur saturation conditions, CS2 destruction was not affected on titania, but was negatively affected on alumina at 150 °C.