A Study of Zn−Ti-Based H₂S Removal Sorbents Promoted with Cobalt Oxides

Abstract

Modification of conventional zinc titanate (ZT) sorbents to increase their reactivity and stability during multiple cycles of sulfidation/regeneration at high and middle temperatures was pursued by addition of Co 3 O 4 . Moreover, evaluation of the modified zinc titanates (ZTC) was conducted using several instruments such as an X-ray diffractometer, Fourier transform infrared spectrometer, scanning electron microscope, and so on. The ZTC sorbents prepared by the physical mixing of the ZT sorbent with 25 wt % of Co 3 O 4 showed an excellent sulfur-removing capacity and no deactivation even after multiple cycles of sulfidation/regeneration in both high-and middle-temperature conditions. The cobalt permeated the Zn 2 TiO 4 lattice, leading to a new spinel phase, ZnCoTiO 4 . It worked not only as an active site during the sulfidation process but also as a support to prevent zinc migration to the outside of the sorbents and to minimize volume expansion/contraction. Under middle-temperature conditions, the phase separation of the ZTC sorbent including a cobalt oxide intermediate in addition to the ZnCoTiO 4 spinel structure was observed. Also, the cobalt additive increased the regeneration capacity of Zn-based sorbents because it played an important role as the catalyst for oxidation.

The characterization of Co xZn7-xSb2O12 spinel obtained by the pechini method

“…The sample Co 7 Sb 2 O 12 ( Figure 11) presented four bands that can be attributed to the spinel structure. These were in the regions: 19 and Jun et al 20 observed that Co 3 O 4 absorbs in the regions near 210, 216, 560 and 660 cm -1 . Thus, the additional bands can be related to the presence of Co 3 O 4 , which was not observed by X-ray diffraction.…”

Influence of Zn substitution on the structural and magnetic properties of Co1-xZnxFe2O4 nano-ferrites

“…This is due to its direct relationship with anisotropy constant of the sample. The anisotropy constant decreases with increasing Zn 2+ content, which in turn decreases the domain wall energy [25,26].…”

Effect of Zn Substitution on the Magnetic Properties of Cobalt Ferrite Nano Particles Prepared Via Sol-Gel Route

“…Hence in the multi domain region the coercivity decreases as the particle diameter increases. A decrease in coercivity as observe in Figure 6, with increase in zinc concentration may be attributed to the decrease in anisotropy field, which in turn decreases the domain wall energy [18,19]. …”