H2 production via H2S decomposition over activated carbon supported Fe- and W- catalysts.

This study aims to investigate sawdust-based activated carbon (AC) as catalyst, and as catalyst support for Fe and W in H 2 production by H 2 S decomposition. Activated carbon was prepared with the chemical agent phosphoric acid. The wet impregnation method was used in the preparation of sawdust-based AC supported Fe and W containing catalysts. Commercial mesoporous activated carbon was also used for comparison purposes as catalyst support. N 2 adsorption-desorption isotherms of AC showed the presence of both micro/mesoporosity. ICP-OES analyses revealed the phosphorus in the structure of all prepared catalysts. Raman, DTA profiles, and XRD patterns of AC and CMC showed that AC and CMC have amorphous and graphite carbon, respectively. The higher H 2 S conversion values obtained with AC-supported catalysts compared to CMC-supported catalysts can be attributed to the presence of oxygenated phosphorus in the structure of AC. XPS analysis revealed the presence of WO 3 in fresh 10W@AC, and Fe 2 O 3 in fresh 10Fe@AC. After the reaction, XPS analyses showed the formation of WS 2 on the 10W@AC catalyst, while it revealed the presence of elemental sulfur and sulfate structures on the 10Fe@AC catalyst. In catalysts containing Fe and W, it is observed that metal-sulfide compounds formed on the surface and in the bulk phase during reaction, as well as phosphorus compounds, may have catalytic activity. H 2 S conversions over AC and AC-supported catalysts were close to the thermodynamic equilibrium conversion value. To determine the possible product distribution during reaction, the reactor exit stream was analyzed by an online connected FTIR spectrometer. FTIR spectra indicated the formation of CS 2 , CO, and some CO 2 in the reactor exit stream using AC and AC-supported Fe and W catalysts. The activity test results showed that activated carbon prepared by phosphoric acid and activated carbon-supported Fe and W are promising catalysts for H 2 production via H 2 S decomposition. [Display omitted] • Activated carbon, Fe, W catalysts show high and stable activity in H 2 production. • 89% of the equilibrium conversion was achieved with all catalysts at 800 °C. • After the reaction, FeS and WS 2 were formed as a result of the structural change. • Besides the H 2 production by H 2 S decomposition, CS 2 and CO were also formed. [ABSTRACT FROM AUTHOR]