Cleaning of gaseous hydrogen chloride in a syngas by spray-dried potassium-based solid sorbents

Abstract

There are corrosive gases such as H₂S and HCl in a coal- or biomass-derived syngas. HCl can be removed by Na₂CO₃ or K₂CO₃ at hot temperatures. Hot syngas cleaning has the advantage of improving thermal efficiency. We investigated HCl removal by spray-dried potassium-based solid sorbents which were originally developed for post-combustion CO₂ capture. Both fresh and spent CO₂ sorbents were tested to confirm the applicability as a sorbent for HCl cleaning. Saturation chlorine sorption capacity was measured using a fixed-bed reactor at a temperatures of 300–500 °C under an ambient pressure. Both fresh and spent CO₂ sorbents showed saturation chlorine sorption capacity above 15 wt%. HCl removal performance of the sorbents was investigated in a micro fluidized-bed reactor and a bench-scale bubbling fluidized-bed reactor. HCl concentration was lowered from 150–900 ppmv to less than 5 ppmv and from 130–390 ppmv to less than 1 ppmv in a micro fluidized-bed reactor and in a bench-scale bubbling fluidized-bed reactor, respectively, at 300–540 °C and 20 bar. It could be concluded that both fresh and spent spray-dried potassium-based CO₂ sorbents could be utilized as a disposable HCl sorbent for hot syngas cleaning.