Decomposition of the sulfates of copper, iron (II), iron (III), nickel, and zinc: XPS, SEM, DRIFTS, XRD, and TGA study

Several pure zinc oxide materials, prepared with different methods (combustion synthesis and a modified version of the citrates method) and calcined at different temperatures, were investigated as low-temperature desulfurizing sorbents from gaseous streams (syngas, in particular). Comparative tests with a commercial sorbent were also carried out. The sulfidation performance was investigated in a fixed-bed reactor in terms of breakthrough curves at 250 °C. Fresh and sulfided samples were characterized by X-ray diffraction, scanning electron microscopy−energy dispersion spectroscopy, BET, pore volume, pore size, and pore size distribution analyses. The ZnO sorbent prepared by the citrated method calcined at 400 °C showed the most durable effectiveness in reducing sulfur from 100 to less than 1 ppm:  its breakthrough time is about 9 h measured at a space velocity of about 105 h-1. Its regenerability was evaluated by subsequent sulfidation−thermal regeneration cycles. A numerical model was also developed and ...

Zinc oxide sorbents for the removal of hydrogen sulfide from syngas

The sorption of hydrogen sulfide from hot syngas by metal oxides over supports.

Performance of zinc oxide based sorbents for hot coal gas desulfurization in multicycle tests in a fixed-bed reactor

LaMeOx/SBA-15 (Me = Zn, Co and Fe) desulfurizers were synthesized by a sol–gel method and their performance for H2S removal from hot coal gas was investigated. The results of eight successive desulfidation–regeneration cycles revealed that the LaFeO3/SBA-15 desulfurizer shows high performance and stability for H2S removal. The results of BET, XPS, HRTEM and XRD characterization suggested that the SBA-15 structure of used LaMeOx/SBA-15 remained intact. It was found that there is only partial reduction of Fe3+ ions in LaFeO3/SBA-15 by hydrogen in hot coal gas, a factor considered to be favorable for LaFeO3/SBA-15 sulfidation. The metal oxides supported on SBA-15 can effectively suppress mechanical disintegration and improve stability of LaMeOx/SBA-15. Among the three desulfurizers, LaFeO3/SBA-15 performs the best.

Preparation and desulfurization performance of LaMeOx/SBA-15 for hot coal gas

High-temperature desulfurization using zinc ferrite: Reduction and sulfidation kinetics

High-temperature desulfurization using zinc ferrite: regeneration kinetics and multicycle testing

High-temperature desulfurization using zinc ferrite: solid structural property changes

Global kinetic studies using single cylindrical pellets of zinc ferrite were carried out in an electrobalance reactor. Most of the research utilized zinc ferrite. Both the sulfidation and regeneration reactions of zinc ferrite were studied as a function of temperature and gas composition. Sorbent structural properties such as specific area, pore volume, and pore size distribution were measured prior to reaction and at various stages in the sulfidation-regeneration cycle. A maximum desirable operating temperature of approximately 650/sup 0/C (1200/sup 0/F) has been established for both the sulfidation and regeneration phases. The global kinetic data for the sulfidation cycle over a wide range of temperatures (500-700/sup 0/C) and for the regeneration cycle near 650/sup 0/C can be described quite well by the unreacted core model assuming that the global rate is controlled by transport resistances. Near 550/sup 0/C the regeneration reaction is complicated by ZnSO/sub 4/ formation and near 750/sup 0/C severe structural property changes accompany regeneration. These complications prevent the application of the unreacted core model to the regeneration reaction at these temperatures. The two transport parameters in the simplified unreacted core model, the mass transfer coefficient and the effective diffusivity of the reactant gas through the porous product layer,more » were determined by least squares fit of the experimental data. Single pellet kinetic results are required before reasonable attempts can be made to model an integral (multipellet) desulfurization reactor. The ability to describe the single pellet kinetics in terms of the simple unreacted core model is quite fortuitous in reducing both the mathematical complexity and the computational requirements associated with integral reactor modeling. 27 refs., 62 figs., 20 tabs.« less

G.D. Focht

Papers

High-temperature desulfurization using zinc ferrite: Reduction and sulfidation kinetics

High-temperature desulfurization using zinc ferrite: regeneration kinetics and multicycle testing

High-temperature desulfurization using zinc ferrite: solid structural property changes

Structural property changes in metal oxide hot coal gas desulfurization sorbents. Final report. [Zinc ferrite]