Synthesis of mesoporous Pt@KIT−6/SAPO−11 VIA in situ encapsulation to catalyze the decarboxylation of oleic acid to C8–C17 alkanes.

BACKGROUND: A series of mesoporous Pt@KIT−6/SAPO−11 catalysts with SiO2:Al2O3 molar ratios of 0.3, 0.4, or 0.5 and Pt loadings of 0.4, 0.8, or 1.2 wt% were prepared via an in situ encapsulation process using a PEO − PPO − PEO triblock copolymer (EO20PO70EO20, P123) as the mes. China 750001 oporous template and KIT−6 molecular sieves as the silicon source. RESULTS: These catalysts were characterized by transmission electron microscopy (TEM), specific surface area analysis, and pyridine–infrared spectroscopy (Py − IR). The results showed that Pt nanoparticles with particle sizes of 3–7 nm were uniformly dispersed on the supports. These materials also exhibited good mesoporous structures with specific surface areas of 138–197 m2/g and average pore sizes of 7.1–9.9 nm. The specimens having a SiO2:Al2O3 molar ratio of 0.4 also showed an orderly strip−shaped pore structure. The Py − IR results indicated that the catalysts had both Brønsted acid and Lewis acid sites, with total acid contents in the range of 77.8–131.1 μmol/g. CONCLUSION: The decarboxylation of oleic acid using these materials under CO2 was examined. The catalyst with a SiO2:Al2O3 molar ratio of 0.4 and a Pt loading of 0.8 exhibited the best catalytic performance and a C8 − C17 alkanes yield as high as 85.1% at 340 °C by using a catalyst−to−oil mass ratio of 1:10 and a reaction time of 5 h. This performance was attributed to the ordered mesoporous structure of this catalyst along with its high surface area (173 m2/g), good crystallinity (92.8%), suitable acid content (98.6 μmol/g), and abundant Pt metal active sites. © 2022 Society of Chemical Industry (SCI). [ABSTRACT FROM AUTHOR]