Nickel impregnated Pt/H-β and Pt/H-mordenite catalysts for hydroisomerization of n-hexane

Nickel impregnated Pt/H-beta and Pt/H-MOR catalysts with different Ni content were prepared and subjected to hydroisomerization of n-hexane in the presence of flowing H-2 gas. The states of Pt and Ni were identified by ESCA. The particle size measured by TEM shows that average particle size increases with increasing Ni loading. The acidity of the catalysts was measured by TPD of ammonia. The catalytic activity of Ni containing and Ni free Pt/H-beta and Pt/H-MOR catalysts was compared and found that addition of Ni up to a threshold value (0.3 wt% for beta and 0.1 wt% for MOR) increases the n-hexane conversion and dimethyl butanes selectivity due to better metal-acid synergism and decreases the amount of cracked products. When the Ni amount exceeds the threshold values the conversion decreases and cracked products increase. Further the Ni impregnation of Pt containing acidic supports increases the sustainability of the catalysts and was found to favor the protonated cyclopropane (PCP) intermediate mechanism in n-hexane isomerization. beta zeolite was found to be a better potential support than mordenite and the isomerized product mixture shows better octane number.