Based on the newly found autoregenerative Ni/ZnO catalyst, a practical adsorptive hydrodesulfurization (HDS) catalyst of kerosene for the fuel cell (FC) was developed and evaluated. The content of surface Ni on the Ni/ZnO catalyst is fixed from the balance between the poisoning rate and the regenerating rate. From the results of the long run, 13% Ni/ZnO catalyst was certified as an adsorptive HDS catalyst for the kerosene-fed FC, which will keep less than 0.03 wt ppm of average sulfur for 1 year, consuming 36% of ZnO. When this catalyst is applied, a 1-year operation of the petroleum-fed FC cogenerations and a 1110 thousand-km running of the model FC vehicles are considered possible.

An idea to regenerate sulfur-poisoned Ni catalyst in flowing H2 was tried. That is, sulfur-poisoned Ni catalyst particles are mixed with ZnO fine particles in a H2 atmosphere at 600K, then the each poisoned catalyst particle would releases a few ppb of H2S through the H2 atmosphere and the released H2S would be accepted on neighboring ZnO particles.Then, a million-fold effective improvement in the regeneration of sulfur-poisoned Ni catalyst in a flow of H2 would be realized.After only a 90h of trial operation, sulfur-poisoned 60% Ni/Al2O3 catalyst was regenerated.Applying this idea, 12.3% Ni/ZnO was prepared and tested as a model catalyst for adsorptive ultra-deep hydrodesulfurization (UD-HDS) of kerosene in a stream of H2 containing 25% CO2 at 600K. Residual sulfur in the treated kerosene was not detectable (<0.06 wt ppm) by the ready-made sensitive sulfur analyzer even after 800h of operation.Comparing with the conventional Ni/Al2O3 catalyst, the Ni/ZnO catalyst did not produce any CH4. The ZnO support is regarded to serve as a kind of SMSI and to regenerate Ni catalyst automatically in the HDS. To the best of our knowledge, this is the first time that the regeneration of the sulfurpoisoned Ni catalyst in a H2 stream was realized and the automatic regenerative Ni catalyst for adsorptive HDS was demonstrated.Other materials for the catalyst of adsorptive UD-HDS were investigated. Al2O3 and Fe2O3 were useful as sub-materials, however, Cu, Co, Mo, Pd, and Pt were not comparable to Ni and ZnO.

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.