Melting-assisted solvent-free synthesis of SAPO-11 for improving the hydroisomerization performance of n-dodecane

A novel melting-assisted solvent-free route using solid oxalic acid was proposed for the post-treatment of SAPO-11 zeolite, followed by loading with 0.5 wt% Pt by the incipient wetness impregnation method. Subsequently, the performance of the obtained bifunctional catalysts toward the hydroisomerization of n-dodecane was examined. The prepared samples were characterized by XRD, SEM, BET, XRF, Py-IR, and solid-state NMR. From the results, it was found that the high crystallinity and uniform morphology were retained after the post-treatment and that more (002) crystal faces were exposed, which was beneficial since more acid sites were provided. More importantly, the total Bronsted acid sites and the ratio (Ra) of the micropore area to the total surface area were optimized by this method. Thus, the catalytic performance was enhanced significantly, and the prepared Pt-SAPO-11-10% catalyst had the highest i-dodecane yield of 80.1% compared to 55.3% of Pt–SAPO-11. Expectedly, this facile and cost-effective method is promising for the hydroisomerization of normal paraffin in the production of lubricant base oils.