Highly effective Pd/ZSM-12 bifunctional catalysts by in-situ glow discharge plasma reduction: the effect of metal function on the catalytic performance for n-hexadecane hydroisomerization

Abstract

BackgroundAlthough the zeolite-based bifunctional catalysts loaded noble metal have higher catalytic activity, it is still a great challenge to reduce the noble metal loading while maintaining the high selectivity for branched isomers in the long-chain n-alkane hydroisomerization. MethodsA novel method of in-situ glow discharge plasma reduction at room temperature is introduced to prepare the highly effective bifunctional catalysts (xPd/Z12-E) with 0.1 wt.% and 0.3 wt.% Pd loaded on nanosized ZSM-12 zeolite for n-hexadecane hydroisomerization. For comparison, xPd/Z12-C catalysts with the same Pd loadings were prepared by the conventional hydrogenation reduction method. Significant FindingsThe maximum yield of iso-hexadecane achieved over the xPd/Z12-E catalyst is much higher than that of xPd/Z12-C catalysts, which is originated from the synergetic effects of the larger ratio of metal to acid sites and improved hydrogen activation ability caused by more exposed Pd (111) facets. Besides, the 0.1Pd/Z12-E catalyst exhibits excellent catalytic stability. Our work provides a effective pathway for the development of bifunctional catalysts for production of clean biodiesel with outstanding low-temperature fluidity.