The direct and selective partial H2S oxidation to elemental sulphur at low temperature may be an interesting alternative to the traditional methods of H2S abatement if an active and selective catalyst is available.
In our previous works, a screening of vanadium-based catalysts supported on the metal oxide (V2O5- TiO2, V2O5-CeO2, V2O5-CuFe2O4) was performed in the range of temperature 50-250 °C; among all the catalysts investigated, the V2O5/CeO2 catalyst has showed the better catalytic performance in terms of H2S conversion (>95 %) and a low SO2 selectivity (~13 %) at T= 250 °C.
Based on these promising results, further investigations on V2O5/CeO2 catalyst were performed to investigate the influence of the inlet concentration of H2S (250-1000 ppm), the gas hourly space velocity (GHSV=15,000-45,000 h-1) and the molar feed ratio (O2/H2S=0.4-0.5) in order to minimize the selectivity of the system to SO2.
Preliminary results relevant to the effect of the gas hourly space velocity and the inlet concentrations of H2S, showed that they did not contribute to reduce significantly the SO2 selectivity, while interesting result in terms of SO2 selectivity was obtained with a sub-stoichiometric feed ratio (O2/H2S = 0.4), for which it is resulted drastically reduced from 13 % to 4 % without any significant reduction of the H2S and O2 conversions.
From these good results, future works will be performed to investigate the effect of vanadium load by studying samples in the range 2.55-10 %wt in order to determine the optimal catalyst formulation and operative conditions to obtain a very high H2S conversion and the SO2 selectivity minimization.