Highly Selective Hydrodeoxygenation of Dibenzofuran into Bicyclohexane over Hierarchical Pt/ZSM-5 Catalysts

Abstract

Fabricating zeolite-supported catalysts with excellent catalytic performance for hydroconversion of bio-oils into high-quality fuels is still a great challenge. Herein, hierarchical ZSM-5 zeolites were successfully synthesized with 3-[(trimethoxysilyl) propyl] octadecyldimethylammonium chloride as a mesoporous template. The hierarchical ZSM-5 supported Pt catalysts (Pt/HZ-x) were used to enhance the hydrodeoxygenation of dibenzofuran into bicyclohexane, and the influence of acidity distribution on the reaction pathways was investigated by tailoring the Si/Al molar ratios (50, 75, and 100). For all catalysts, cycloalkanes were produced via the partial hydrogenation of the aromatic rings to generate tetrahydrodibenzofuran, followed by the cleavage of CO bond. The optimal bicyclohexane selectivity (86.8%) was obtained on Pt/HZ-75 catalyst due to the good synergistic effect between metal dispersion and acid distribution. This catalyst also showed excellent stability because of its strong metal−support interactions. Even after reused five times, the catalytic activity was almost unchanged compared with the fresh one. Furthermore, the possible reaction pathways for conversion of dibenzofuran into bicyclohexane over Pt/HZ-x catalysts were developed.

Redispersion of Pt nanoparticles encapsulated within ZSM-5 at high temperature oxygen for partial oxidation of methane

“…3a-f). The size of the synthesized catalysts are smaller than reported in the literature [34], which is attributed to two stages of crystallization method. Speci cally, rst stage is the crystallization at 100 ℃ for 48 h to form zeolite crystal nucleus, and later crystallization at 170 ℃ make it grow up [30,35].…”

Tuning Pt Location and Intimacy between Pt–Acid Active Sites in Pt/ZSM-5 Bifunctional Catalysts for Effective Alkylation of Benzene with Ethane

“…The consumption peak at 500–600 °C is mainly due to the reduction process of Pt 2+ located at the secluded position or interior of the zeolite nanosheet to metal Pt 0 , as well as the reduction of platinum cations in coordination with some silanol groups (Si–OH) in the zeolite . Finally, the consumption peak at temperatures >600 °C is likely associated with those Pt species that exert a strong interaction with the framework aluminum species . As seen in Figure , EN/0.2 has only two hydrogen consumption peaks between 400–500 and 500–600 °C, with the predominant peak at 500–600 °C.…”

“…This indicates that Al in the ZSM-5 support accepts more electrons from Pt sites in IE/0.2 and IWI/0.2 than in EN/0.2, consistent with the stronger Pt−acid interactions in IE/0.2 and IWI/0.2 as revealed by the CO−DRIFT spectroscopy and H 2 -TPR results. Furthermore, as seen in the enlarged spectra in Figure 6b, the peaks at 71.1−71.6 and 74.5−75.0 eV are assigned to Pt 0 , 38 and the peaks at 72.2−72.7 and 75.6−76.1 eV are allocated to the Pt 2+ species. 40,41 Typically, the binding energy for Pt 0 and Pt 2+ is located at 71.2 and 72.3 eV, respectively, in the Pt 4f 7/2 region.…”

“…37 Finally, the consumption peak at temperatures >600 °C is likely associated with those Pt species that exert a strong interaction with the framework aluminum species. 38 As seen in Figure 5, EN/0.2 has only two hydrogen consumption peaks between 400−500 and 500−600 °C, with the predominant peak at 500−600 °C. This indicates that the Pt species on this catalyst are preferentially located in the interior of zeolite.…”