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Pt(NH 3 ) 4 (NO 3 ) 2 , Pt(NH 3 ) 4 (Ac) 2 , (NH 4 ) 2 PtCl 4 , and H 2 PtCl 6 were used to prepare Pt/SAPO-11 catalysts to investigate the effect of Pt precursors on the hydroisomerization of n -dodecane. The catalyst derived from Pt(NH 3 ) 4 (NO 3 ) 2 displays the best hydroisomerization activity and selectivity among these precursors. The hydroisomerization conversion of n -dodecane is affected by the platinum particle size, platinum dispersion, the location of platinum, and the valence state of platinum. The selectivity of n -dodecane is determined by the number of Brønsted acid sites and Pt crystal planes. These conclusions are verified by combining transmission electron microscopy, high-resolution transmission electron microscopy, hydrogen temperature programmed reduction, NH 3 -temperature programmed desorption, and Py-IR studies. The catalyst prepared with Pt(NH 3 ) 4 (NO 3 ) 2 as the precursor exhibits the smallest platinum particle size and the highest platinum dispersion. Most of the platinum particles are supported on the external surface of SAPO-11 with the Pt(111) crystal face. Such a catalyst also possesses a suitable number of Brønsted acid sites and then displays the best catalytic performance. Obviously, the use of various precursors for the Pt-based catalyst can significantly affect the performance of Pt/SAPO-11 for the hydroisomerization of n -dodecane.

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Site shifting by templated coordination aimed at enhancing the performance during n-butene skeletal isomerization under severe conditions.

ZSM-22 zeolites were synthesized using different structure-directing agents (SDAs) with varying alkyl chain lengths, including n-alkyldiamines (DAB, DAH, DAO, and DAD) and lauryl amine (LA). The characteristics of the resulting samples (denoted as “Z-SDA”) revealed that optimal elongation of SDA alkyl chains brought about a decrease in crystallization time while retaining ZSM-22 crystal phase stability. The morphology and acidity of the samples varied as the alkyl chain length of the SDAs increased. The average crystal length ranged from 13 μm to 250 nm, and the total acid content showed a downward trend, while each sample possessed nonlinear acid site distributions. Additionally, ZSM-22-supported Pt catalysts were obtained and probed using the n-hexadecane hydroisomerization process. It was found that the activity and i-hexadecane selectivity gradually increased with the alkyl chain length of the SDAs (C4–C10). Notably, Pt/Z-DAD achieved >70% yield under specific reaction conditions, which could be attributed to the abundant mesopore network and high proportion of weak Brønsted acid site distributions.

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