Ni Catalyst on Zsm-22 Nanofibers Bundles with Good Catalytic Performance in the Hydroisomerization of N-Dodecane

Developing non-noble catalyst with high performance is significant in the hydroisomerization of long-chain n-alkane to iso-alkanes. Herein, ZSM-22 with nanofiber bundles morphology was successfully synthesized without any additives and used to prepare Ni catalyst (Ni/NB-HZSM-22, Ni loading 1.0 wt.%) for long-chain n-alkanes hydroisomerization. The obtained Ni/NB-HZSM-22 catalyst exhibited much higher intrinsic catalytic activity (TOF = 0.077 s-1) in the hydroisomerization of the n-dodecane than a conventional needle-shaped ZSM-22 supported Ni catalyst (Ni/C-HZSM-22, 0.026 s-1), especially higher isomerization activity (TOFiso, 0.071 s-1) than the Ni/C-HZSM-22 catalyst (0.021 s-1). Meanwhile, the Ni/NB-HZSM-22 catalyst had lowed cracking/iso-dodecanes (0.08) and di-branched/mono-branched (0) ratios than the Ni/C-HZSM-22 catalyst (0.25 and 0.07) after extrapolation n-dodecane conversion to zero. This result is mainly attributed to the nanofiber–bundled NB-HZSM-22 with suitable acidity, leading to good synergistic catalysis between metal and acidic function for the Ni/NB-HZSM-22 catalyst. The Ni catalyst on the parent NB-ZSM-22 was less active but similar optimal iso-dodecanes yield, compared with the Ni/NB-HZSM-22 catalyst. Also, the Ni/NB-HZSM-22 catalyst showed the maximum iso-dodecanes yield of 74.8%, which was much better than the Ni/C-HZSM-22 catalyst (58.7%), even better than a Pt catalyst on C-HZSM-22 (64.2%). These results suggested that the Ni catalyst on the NB-HZSM-22 was a promising candidate for the hydroisomerization catalysts.