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PublicationCatalysis Today

Photocatalytic-based strategies for H2S elimination

Authors:R. Portela, Silvia Suárez Gil, Søren Birk Rasmussen , N. Arconada , Yolanda Castro , Alicia Durán , Pedro Ávila García, Juan Manuel Coronado , Benigno Sánchez
Groups of research:Spectroscopy and industrial catalysis
The mechanism of H2S elimination in gas phase by means of heterogeneous photocatalysis was investigated. The main drawbacks for a real application were identified to be related to the nature of the reaction products: SO2 is toxic, corrosive and malodorous, and SO42- accumulates on the photocatalyst surface leading to deactivation. In order to face this challenge, supported photocatalysts with different properties were synthesised to investigate several strategies according to the photocatalyst selectivity. On one hand, two different approaches for coupling adsorption and photocatalysis have been proposed to solve the problem of SO2 release and prolong the catalyst lifetime. First, porous and SO2-selective photocatalysts were synthesised by sol-gel with the help of surfactants. These materials presented good conversion values and suffered slower deactivation; an external adsorption unit might retain the SO2 produced. Alternatively, improved adsorption capability of the photocatalyst was obtained through the synthesis of coated and incorporated hybrid TiO2-SiMgOx composites, whereby SO2 release was avoided and the lifetime of the photocatalyst prolonged. The combination in a hybrid material of an efficient photocatalyst and an adsorbent that may act as support constitutes a promising alternative for H2S elimination due to the coupling of photocatalytic and adsorptive properties. On the other hand, photocatalyst regeneration was achieved by rising with water, which recovered the active sites. Moreover, when a 1 M KOH solution was used in the process, the creation of new basic active sites resulted in an increase of the photocatalytic activity, even higher than for the fresh material.
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