Iron- and Cobalt-Doped Ceria–Zirconia Nanocomposites for Catalytic Cracking of Naphtha with Regenerative Capability

Abstract

Series of nanosized iron-and cobalt-doped ceria−zirconia nanocomposites were prepared using a hydrothermal synthesis technique at 180 °C for 24 h, with the successful novel incorporation of both Co and Fe on ceria−zirconia, for n-hexane catalytic cracking. Effects of dopant ions on the improvement of intrinsic properties of ceria−zirconia nanocomposites were investigated using disparate characterization techniques. The synthesized ceria−zirconia nanocomposites exhibited similar X-ray diffraction (XRD) patterns, indicating full fusion of the metal ions into the ceria−zirconia lattice structure. The synthesized nanocomposite catalysts were tested for n-hexane cracking over 10 h time-on-stream, with no previous study or report for catalytic cracking of hexane via ceria−zirconia nanocomposites. Relatively high ethylene and propylene selectivity (both >62%) was obtained over CZ, FeCoCZa, and FeCoCZb over time-on-stream. Comparatively, the best catalytic activity and stability was exhibited by FeCoCZa with higher n-hexane conversion. Temperature and catalyst weight per feed flow rate (W/F) variations were investigated using the best catalyst (FeCoCZa). Higher conversions were obtained at higher temperature and lower W/F but with varied product selectivity and yield, over time-on-stream. In addition, the spent catalysts were successfully regenerated after catalytic testing via calcination at 600 °C for 4 h and reused for two additional cycles.

Fluidizable Fe–Co/Ce–ZrO2 Catalysts for Steam Reforming of Toluene as a Tar Surrogate in Biomass Gasification

“…This suggests the formation of solid solution between Fe–Co and with Ce–ZrO 2 composite. The reduction peak at 684 °C observed with Ce–ZrO 2 composite (Cat-A) was attributed to reduction of Ce 4+ to Ce 3+ . This reduction peak was shifted to the lower temperature after incorporation of Fe–Co, as seen with Cat-B and Cat-C.…”

“…The absence of additional peak on Cat-B and Cat-C compared to Cat-A is an indication of a complete incorporation of Fe 3+ and Co 2+ ions into the lattice structure of Ce−ZrO 2 composite (Cat-A) and preserving the same structure. 22,25 This is possibly due to the solubility of the dopant ions, which promotes Zr 4+ , Fe 3+ , and Co 2+ to substitute Ce 4+ . Indeed, the synergetic effect of each involving ions promotes the formation of ceria− zirconia composites.…”

“…The multicomponent catalysts were synthesized using hydrothermal techniques as outlined in a previous works of our research group. , To synthesize the ceria–zirconia composite, respective metal precursors were dissolved in deionized water by stirring at 500 rpm for 1 h. Meanwhile, KOH solution (Panreac, 85%) was steadily added (as a precipitant) to the solution and stirred continuously for another 3 h at ambient temperature. The solution was then spilled in the PTFE-lined steel autoclaves and put in the oven for hydrothermal synthesis at 180 °C for 24 h and a tumbling speed of 40 rpm.…”

Zirconia-Based Nanocatalysts in Heavy Oil Upgrading: A Mini Review

“…On the other hand, the screening of some metal oxides and their mixed oxides to water tolerance ,, showed that MoO 3 -ZrO 2 and WO 3 -ZrO 2 were the most stable mixed oxides in water. However, since MoO 3 -ZrO 2 showed better conversion to the esterification of fatty acids, this catalyst was considered as one of the most potential mixed oxides for upgrading heavy oil …”

“…However, since MoO 3 -ZrO 2 37 showed better conversion to the esterification of fatty acids, this catalyst was considered as one of the most potential mixed oxides for upgrading heavy oil. 38 Zirconia is widely used for solid oxide fuel cell, 39 peat pyrolysis, 40 and cleanup gasification gas. 41 For instance, in biomass gasification, zirconia is more resistant to sulfur, while at the same time, zirconia removes tar and ammonia.…”