Selective Oxidation of Hydrogen Sulfide to Sulfur Using Vanadium Oxide Supported on Porous Clay Heterostructures (PCHs) Formed by Pillars Silica, Silica-Zirconia or Silica-Titania.

Juan Cecilia,José López Nieto,M Soriano,Enrique Rodríguez-Castellón,Alejandro Natoli

doi:10.3390/ma11091562

Abstract

Vanadium oxide (V2O5) species has been supported on different porous clay heterostructures (with silica pillars, silica-zirconia with a molar ratio Si/Zr = 5 and silica-titania with a molar ratio Si/Ti = 5) by wetness incipient method. All catalysts were characterized by X-ray diffraction (XRD), N2 adsorption-desorption at −196 °C, NH3 thermoprogrammed desorption (NH3-TPD), Raman spectroscopy, diffuse reflectance UV-Vis and X-ray photoelectron spectroscopy (XPS). After that, the catalytic activity of the vanadium-based catalysts was evaluated in the selective oxidation of H2S to elemental sulfur. The catalytic data show that both the activity and the catalytic stability increase with the vanadium content, obtaining the highest conversion values and sulfur yield for the catalysts with vanadium content of 16 wt.%. The comparison among all supports reveals that the incorporation of TiO2 species in the pillars of the PCH improves the resistance to the deactivation, attaining as best results a H2S conversion of 89% for SiTi-PCH-16V catalyst and elemental sulfur is the only compound detected by gas chromatography.

Highlights

The depletion of petroleum reserves has given rise to use of feedstock with lower quality and higher content of sulfur, nitrogen, oxygen and metals
Several porous clay heterostructures (PCHs), formed by silica, silica-zirconia or silica-titania pillars, have been used as catalytic supports to disperse V2O5 species, which have shown to be active in the selective oxidation of H2S to elemental sulfur
Several porous clay heterostructures (PCHs), formed by silica, silica-zirconia or silica-titania pillars, have been used as catalytic supports to disperse V2 O5 species, which have shown to be active in the selective oxidation of hydrogen sulfide (H2 S) to elemental sulfur

Summary

Introduction

The depletion of petroleum reserves has given rise to use of feedstock with lower quality and higher content of sulfur, nitrogen, oxygen and metals. The most common technology used is the Claus process [3], where H2 S can be recovered in the form of elemental sulfur. This reaction displays thermodynamic limitations, due to the fact that between 3–5%. In order to improve the efficient removal of H2 S, several purification processes have been proposed, such as adsorption, absorption, wet oxidation, and selective catalytic oxidation [4] Among these processes, selective catalytic oxidation of H2 S to elemental sulfur using oxygen from air [3] has been the most attractive process to remove H2 S of Materials 2018, 11, 1562; doi:10.3390/ma11091562 www.mdpi.com/journal/materials

Methods

Results

Conclusion