Ultra-deep Hydrodesulfurization of Kerosene for Fuel Cell System. (Part 2). Regeneration of Sulfur-poisoned Nickel Catalyst in Hydrogen and Finding of Auto-regenerative Nickel Catalyst.

Abstract

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.

Desulfurization mechanism of FCC gasoline: A review

“…A similar mechanism was recently proposed by Aksenov et al [26] and Chica et al [27,28]. Tawara and co-workers [29] reported that 12.3% Ni/ ZnO was applied as a model catalyst for adsorptive ultradeep HDS (UD-HDS) of kerosene in a stream of H 2 containing 25% CO 2 at 600 K. The experiments results showed that residual sulfur in the treated kerosene was not detectable ( < 0.06 wt-ppm) even after 800 h of operation. They first reported that the regeneration of the sulfur poisoned Ni catalyst in a H 2 stream was realized and the automatic regenerative Ni catalyst for adsorptive HDS was demonstrated.…”

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

“…The measurement7) was carried out by TPD-MS using a flow-through cell and the GC-NO-pulse procedure as Eqs. (1) and (2). The complicated analysis of the measured data was carried out using software developed in this laboratory7).…”

Ni/ZnO-based Adsorbents Supported on Al2O3, SiO2, TiO2, ZrO2: A Comparison for Desulfurization of Model Gasoline by Reactive Adsorption

“…As represented in XRD characterization, there is no obvious reflection for crystalline ZnO and Al 2 O 3 in the sample NiZnO/ Al 2 O 3 , while broad diffraction peaks of ZnAl 2 O 4 are found, it indicates that there are strong interactions between ZnO and Al 2 O 3 . Tawara et al 10 reported that Ni/ZnO is an autoregenerative adsorptive UD-HDS catalyst, the ZnO support is regarded to regenerate sulfur-poisoned surface Ni to active surface Ni by accepting H 2 S. In the reactive adsorption desulfurization system, ZnO is considered to the active component, while ZnAl 2 O 4 belongs to the non-active component. So the formation of ZnAl 2 O 4 in the sample NiZnO/ Al 2 O 3 may be the reason for lower activity.…”