CrOx modified particles size and electronic density of Ni catalyst on ZSM-23 for enhanced hydroisomerization performance of long-chain n-alkanes.

[Display omitted] • CrO x -modified Ni on ZSM-23 has high-performance in n -C 16 hydroisomerization. • Microporous ZSM-23 is suitable to prepare high-performance Ni m Cr n /ZSM-23 catalyst. • Particle size and electronic state of Ni is affected by the interaction of Ni with CrO x. • Ni 2.0 Cr 2.0 /ZSM-23 outperforms a Pt on ZSM-23 for n -C 16 hydroisomerization. • The addition of CrO x intensifies the interaction between the NiO x and ZSM-23 support. CrO x -doped Ni catalysts with different Ni/Cr mass ratios on ZSM-23 (Ni m Cr n /ZSM-23) were synthesized using a simple initial wet impregnation method. The influence of CrO x on Ni in the Ni m Cr n /ZSM-23 catalysts was investigated by combining XPS, IR-CO, H 2 -TPR, TEM, and EDX mapping. The obtained results suggested that an intimate contact was formed between Ni and CrO x in the catalysts. The CrO x -modified NiO x species strongly interacted with ZSM-23, facilitating the formation of small sized Ni nanoparticles. Meanwhile, the electronic density around Ni on the catalyst was increased due to the presence of adjacent CrO x. The reaction rate and TOFs over Ni 2.0 Cr 2.0 /ZSM-23 (1.13 × 10-2 mol•g-1•h−1 and 6.8 × 10-2 s−1) are much higher than over Ni 2.0 /ZSM-23 (0.88 × 10-2 mol•g-1•h−1 and 6.2 × 10-2 s−1) in the n -hexadecane hydroisomerization, illustrating the promotion of CrO x in the Ni-based catalyst. The Ni 2.0 Cr 2.0 /ZSM-23 catalyst exhibited the highest iso -hexadecanes yield of 82.9 %, as compared to Pt/ZSM-23 catalyst (78.9 %). [ABSTRACT FROM AUTHOR]