Abstract

An experimental study of hydrogen sulfide adsorption on a fixed bed for biogas purification is proposed. The adsorbent investigated was powdered hematite, synthesized by a wet-chemical precipitation method and further activated with copper (II) oxide, used both as produced and after pelletization with polyvinyl alcohol as a binder. The pelletization procedure aims at optimizing the mechanical properties of the pellet without reducing the specific surface area. The active substrate has been characterized in its chemical composition and physical properties by X-ray Diffraction (XRD), Field Emission Scanning Electron Microscopy (FE-SEM), thermogravimetric analysis (TGA) and N2 physisorption/desorption for the determination of surface area. Both powders and pellets have been tested as sorbents for biogas purification in a fixed bed of a steady-state adsorption column and the relevant breakthrough curves were determined for different operating conditions. The performance was critically analyzed and compared with that typical of other commercial sorbents based on zinc oxide or relying upon specific compounds supported on a chemically inert matrix (SulfaTreat®). The technique proposed may represent a cost-effective and sustainable alternative to commercial sorbents in conventional desulphurization processes.

Highlights

  • IntroductionWhere it represents an undesired compound for many different reasons

  • Hydrogen sulfide (H2 S) is one of the major concerns in civil activities [1] and industrial processes [2]where it represents an undesired compound for many different reasons

  • A 30% NaOH solution was added dropwise to a 0.18 M FeCl3 solution in water kept under vigorous stirring at room temperature, obtaining a brick-red precipitate according to the Equation: FeCl3 + 3 NaOH → Fe(OH)3 + 3 NaCl

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Summary

Introduction

Where it represents an undesired compound for many different reasons. It poses serious safety challenges at a small and large scale owing to accidental releases, whose critical conditions are rapidly reached in case of fugitive emissions in confined or semi-confined spaces [3]. The presence of sulfur compounds in combustibles (fuels) is subject to progressively stringent constraints both for reasons related to environmental protection and considering their secondary corrosive effects on metals, including stainless steel. The inherent safety approach, currently extended to novel emerging processes [5], would require applying the guideword “substitution” to the fuel, technical, economic and strategic constraints can strongly influence the actual achievement of this option [6]. Mercaptans, organic (poly) sulfides and thiophene derivatives are examples of sulfur-carrying molecules typically present in crude oil fractions, which undergo hydrodesulfurization

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