Simultaneous removal of COS and H2S from hot syngas by rare earth metal-doped SnO2 sorbents

• Simultaneous removal of COS and H2S by 40 M percent La-doped SnO2 at 350 °C.
• Small pore size and particle size of the sorbents ascribing to the addition of rare earth metal.
• High improvement of catalytic hydrolysis of COS by La-doped SnO2 and Y-doped SnO2.

The pure SnO2 and rare earth metal (Y and La)-doped SnO2 were synthesized using a co-precipitation method for the simultaneous removal of COS and H2S from hot syngas at 350 °C. The pure SnO2 sorbent exhibited a poor catalytic hydrolysis effect for COS conversion at moderate temperatures of 300–400 °C due to the formation of SnS during the desulfurization. SnS caused a decrease in the COS conversion because the activity of SnS was considerably lower than that of reduced SnO2 for the hydrolysis of COS. The addition of Y and La resulted in the formation of numerous smaller pores and increased the total pore volume of the sorbents. The good dispersion of rare earth metal resulted in the improvement of COS conversion, which produced a higher breakthrough sulfur capacity. As the La content increased, the COS conversion reached nearly 100% and was no longer the restrictive procedure for the simultaneous removal of COS and H2S. The total breakthrough sulfur capacity was 148.4 mg/g when 40 M percent of La was doped into the SnO2 sorbent.