Ultra-deep Hydrodesulfurization of Kerosene for Fuel Cell System. (Part 3). Development and Evaluation of Ni/ZnO Catalyst.

Abstract

Adequate regeneration of NiS in simple Ni/ZnO model catalysts was certified by highly accelerated long runs of the adsorptive ultra-deep hydrodesulfurization (UD-HDS) reaction of kerosene in the laboratory. Then, model Ni/ZnO catalysts containing 5wt% and 12wt% Ni were developed and evaluated in bench plant long life tests. From the results, a practical Ni/ZnO catalyst estimated to have a one-year life was selected.Preparations of catalysts were carried out checking the surface ratio of Ni by chemisorption of NO on a reduced Ni form. In kinetic studies, the apparent reaction order, activation energy, reaction order of H2 and reaction order of CO2 were 1.9-2.2, 31kJ/mol, 0.18, and -2.0, respectively.200l of 12wt% Ni/ZnO catalyst was certified by long life evaluations as an auto-regenerative adsorptive UD-HDS catalyst for the 200kW kerosene-fed phosphoric acid fuel cell (PAFC) system, which was estimated to produce kerosene containing 0.025-0.040wtppm sulfur for at least 5900 h of operation.Because of the small influence of H2 partial pressure, the long run was attained under near atmospheric pressure of 25% CO2 containing H2. By the end of the catalyst life, 36mol% of ZnO was consumed as the acceptor of H2S. The activity of Ni/ZnO catalyst is controlled by the balance of poisoning rate and regeneration rate of surface Ni. The life of the Ni/ZnO catalyst was theoretically interpreted as functions of the regeneration rate of NiS, the rate of sulfur charge, the content of ZnO, and the diffusion resistance of H2S.

A novel reactive adsorption desulfurization Ni/MnO adsorbent and its hydrodesulfurization ability compared with Ni/ZnO

“…Then the sulfur content in outlet oil increased dramatically up to 76.49 ppm at the end of test. These results are consistent with the literatures [22,23].…”

An evaluation of desulfurization technologies for sulfur removal from liquid fuels

“…[286][287][288][289][290][291] In the RADS, sulfur-containing molecules react with a solid adsorbent in the presence of hydrogen. [286][287][288][289][290][291] In the RADS, sulfur-containing molecules react with a solid adsorbent in the presence of hydrogen.…”

“…286 Conoco Phillips Petroleum Co. developed a new S-Zorb process for the production of low-sulfur gasoline by reactive adsorption of sulfur compounds over a solid sorbent at elevated temperatures under a low hydrogen pressure. 88,238,243,[286][287][288][289][290][291][292][293][294][295][296] Tawara et al 288 used Ni/ZnO for bringing down sulfur in kerosene to ,0.1 mg g 21 in the temperature range 270-300 uC under H 2 atmosphere at a pressure of 0.60 Mpa. Ni/ZnO is an ideal adsorbent, in which the ZnO acts not only as an acceptor of sulfur released during the regeneration of sulfided Ni species, but also acts as a co-catalyst for the hydrogenation of sulfur-containing compounds over the surface of Ni species.…”

“…Huang et al 287 carried out sulfur K-edge X-ray absorption near-edge structure (XANES) to investigate the transfer of sulfur species during the RADS process with Ni/ZnO under nitrogen and hydrogen. The results indicated that the desulfurization processes under nitrogen and hydrogen are different in the reaction mechanism (Fig.…”

Adsorptive Separation of Infinitesimal Sulfur Oxide in Naphtha—Screening of Adsorbents—

“…Conventional hydrogenation desulfurization (HDS) results in sulfur levels of about 1 ppm 2) and advanced HDS systems are being investigated to achieve the lower sulfur concentrations necessary. These include using materials that can adsorb and eliminate hydrogen sulfide during HDS 3) . To date, however, no advanced HDS system has reduced sulfur levels below 20 ppb.…”