One-Pot Cation–Anion Double Hydrolysis Derived Ni/ZnO–Al₂O₃ Absorbent for Reactive Adsorption Desulfurization

Abstract

In this study, a series of Ni/ZnO−Al 2 O 3 adsorbents were synthesized by a one-pot cation−anion double hydrolysis (CADH) method. The materials were characterized by N 2 sorption, X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), ultraviolet−visible diffuse reflectance spectroscopy (UV−vis), Raman spectroscopy, and H 2 temperature-programmed reduction (H 2 -TPR). The reactive adsorption desulfurization (RADS) performance of the adsorbents was evaluated in a fixed bed reactor using thiophene in n-octane as a model fuel. Results showed that the adsorbents exhibited better RADS performance than those prepared using the conventional kneading method. The thiophene conversion and sulfur capacity of adsorbents decreased with increasing the crystallization temperature. Among all tested adsorbents, the Ni/ZnO−Al 2 O 3 sample prepared at 28 °C presented the largest adsorption capacity and highest RADS reactivity. Textual characterization results indicated that the sample Ni/ZnO−Al 2 O 3 (28 °C) possessed relatively bigger pore size and larger pore volume than other samples, which may alleviate the pore shrinkage/blockage during the RADS process. A combination of XRD, UV−vis, and H 2 -TPR characterization results demonstrate that a high crystallization temperature favors the growth of inactive ZnAl 2 O 4 crystals and induce the formation of more less-reducible Ni 2+ ion, causing the loss of active ZnO phase and Ni 0 atoms, which may be the reason for the lower RADS activity of the adsorbent synthesized at higher crystallization temperatures.

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.…”

Zn-Zr-Al oxides derived from hydrotalcite precursors for ethanol conversion to diethyl carbonate

“…2) was employed to study the structure of the Zn2ZrxAl-MMO samples. All the samples showed an absorption peak at 375 nm, which is ascribed to the ZnO phase resulting from the transition of O (2p)-Zn (4s-p) [29]. A weak band at ~270 nm was observed in the three samples incorporating Zr and is attributed to ZrO2 nanoparticles [30].…”

Ordered mesoporous Cu-ZnO-Al 2 O 3 adsorbents for reactive adsorption desulfurization with enhanced sulfur saturation capacity

“…ZnO acts not only as a support on the active metal, but also as an S-compound acceptor. The well-dispersed ZnO in the ordered mesoporous sample could facilitate the sulfidation of ZnO by H2S with weak metal-support interaction [49]. This process is beneficial for maintaining the initial state of the active metal of Cu and improving ZnO conversion, thus sustaining good activity over long periods of the RADS process.…”