Regenerable Fe–Mn–ZnO/SiO₂sorbents for room temperature removal of H₂S from fuel reformates: performance, active sites, Operando studies

Abstract

Fe- and Mn-promoted H(2)S sorbents Fe(x)-Mn(y)-Zn(1-x-y)O/SiO(2) (x, y = 0, 0.025) for desulfurization of model fuel reformates at room temperature were prepared, tested and characterized. Sulfur uptake capacity at 25 °C significantly exceeds that of both commercial unsupported ZnO sorbents and un-promoted supported ZnO/SiO(2) sorbents. Sulfur capacity and breakthrough characteristics remain satisfactory after multiple (∼10) cycles of adsorption/regeneration, with regeneration performed by a simple and robust heating in air. XRD shows that both "calcined" and "spent" sorbents contain nano-dispersed ZnO, and XPS confirms conversion of ZnO to ZnS. "Calcined" sorbent contains Fe(3+) and Mn(3+) that are reduced to Mn(2+) upon reaction with H(2)S, but not with H(2). Operando ESR is used for the first time to study dynamics of reduction of Mn(3+) promoter sites simultaneously with measuring sulfidation dynamics of the Fe(x)-Mn(y)-Zn(1-x-y)O/SiO(2) sorbent. Fe cations are believed to occupy the surface of supported ZnO nanocrystallites, while Mn cations are distributed within ZnO.

Zinc oxide nanocubes as a destructive nanoadsorbent for the neutralization chemistry of 2-chloroethyl phenyl sulfide: A sulfur mustard simulant

“…In this regard, active sites over ZnO nanocubes can be revealed concerning their subsequent role in adsorption-destruction mechanism. Similar findings in the surface reducibility and ESR activity of zinc oxide nanostructures have been confirmed in the literature [44][45][46][47]61]. …”

“…Apart from required microscopic, elemental-crystalline spectroscopic, and pore-related surface analyses, it seems crucial to investigate and measure the activity, accessibility, and chemical state of the adsorptive interface which have been approved in the literature as critical factors influencing the decontamination features of destructive nanoadsorbents such as metal oxides, inorganic nanocomposites, and nano-zeolites. Hydrogen temperature programmed reduction (H 2 -TPR) and electron spin resonance (ESR) have been deemed as useful techniques thereof and have been performed to study ZnO nanoadsorbents in recent years [43][44][45][46][47]. Afterward, the adsorption-destruction reactions of 2-CEPS were conducted on the surface of as-prepared ZnO nanocubes and the various effects of polarity of the medium, reaction time, and temperature were pursued.…”

High-temperature desulfurization of hot coal gas on Mo modified Mn/KIT-1 sorbents

“…In the meantime, Mo species was one of the best candidates for coal gas desulfurization at high temperature, and the addition of Mo to Mn-based sorbents would result in an improvement in sulfur capacity [22][23][24]. Dhage et al reported that the doping can change the mechanism of sulfidation, increase the active surface area of MeO x and promote the diffusion of H 2 S, HS À , S 2À ions into MeO x phase [25].…”

Temperature-Programmed Surface Reaction Study of Adsorption and Reaction of H2S on Ceria

“…An aqueous solution of (NH 4 ) 2 CO 3 and (NH 4 ) 2 Ce(NO 3 ) 6 was added dropwise to deionized water at 328 K while keeping the pH at 8-9. The slurry mixture was aged at 328 K for 2 h with constant stirring.…”

“…Many methods have been developed to remove H 2 S, including physical adsorption, chemical adsorption, chemical oxidation, and catalytic combustion [5,6]. Among these methods, physical adsorption and chemical adsorption are the preferred methods.…”