Li Ke,Zhu Yuqiu,Wang Zixuan,Chen Dingkai,Wu Wenwei,Luo Yongming,He Dedong
High concentration of H 2 S in acidic natural gas will lead to poisoning of catalysts for hydrogen production by methane steam reforming, thus limiting the further use of natural gas. Reforming CH 4 by H 2 S can be considered as an alternative route to hydrogen production from methane. This process not only achieves the removal of H 2 S but also obtains chemical raw material CS 2 and clean energy H 2 . By impregnating the Mo source on SiO 2 treated with hydrogen peroxide and then using the catalyst in the CH 4 /H 2 S reforming reaction, we surprisingly found that the conversion rate of CH 4 and H 2 S increased from 28 and 32% to 34% and 43%, respectively, after hydrogen peroxide treatment. The H 2 production rate and the yield of CS 2 increased from 20 mmolH 2 /(g Mo *min) and 52% to 30 mmolH 2 /(g Mo *min) and 65%, respectively. Combining with characterization methods such as X-ray diffraction (XRD), hydrogen temperature programmed reduction (H 2 -TPR), 1 H-based solid-state nuclear magnetic resonance ( 1 H MAS NMR), X-ray photoelectron spectroscopy (XPS), Raman spectra (RS), and transmission electron microscopy (TEM), we found that the hydroxyl concentration of the support increased after hydrogen peroxide treatment, which led to the strengthening of the force between the metal and the support, which was easy to form low-level and small-size MoS 2 , exposing more active sites, and further improving the catalytic activity. This method provides a new idea for hydrogen production by CH 4 /H 2 S reforming and the development of high-performance MoS 2 -based catalysts.
The design of novel practical catalysts is critical for the blossoming of biodiesel green-energy, in which Mo-based catalysts are of particular interest. In this work, an in-situ synthesis method was proposed to obtain a combo Mo-based ionic liquid and SAPO-11 catalyst. The catalyst presents both highly dispersed MoS 2 as hydrodeoxygenation active sites and acidic sites for isomerization. MoS 2 with a few fine layers can be identified based on TEM images and the Brønsted acid sites are dominant based on Pyridine-IR analysis. A great performance of MoS 2 /C 8 min-15 %SA can be obtained under optimized reaction conditions with 100 % conversion of methyl palmitate, 75.0 mol% hydrodeoxygenation to n -C 15 -C 16 , and 20.5 mol % isomerization to i -C 15 -C 16 . The structure and activity of the catalyst can be retained at least for 4 cycles. Thin layers and high sulfurization, large amount of Brønsted acid sites, and suitable reaction conditions are key points to achieve a significant performance and avoid over cracking and deactivation. On basis of detected intermediates and kinetic data simulations, a complex reaction pathway was proposed and the specific k values for each elementary reaction were provided for the hydrodeoxygenation and isomerization of methyl palmitate.
A series of molybdenum-based catalysts were prepared using UiO-66 modified with functional ligands as a carrier. The catalyst structure was characterised using XRD, FT-IR, N 2 adsorption desorption isotherms, TEM and XPS. The introduction of -F atom expanded the pore structure of catalyst and increased the specific surface area, resulting in a greater number of active site and more dispersion. The introduction of functional ligands (-F, -NO 2 ) enhanced the electron attraction capacity of catalyst, and improved the microenvironment around the active centre of the catalyst, which contributed to enhance the catalytic performance. The effect of catalyst structure on catalytic activity was investigated using the removal of dibenzothiophene (DBT) from simulated oils as a probe reaction. Under the optimum reaction conditions, the catalyst (UiO-66-NO 2 -F-MoO 3 ) was found to be the most effective for the DBT conversion, reached 99.1%. After 5 desulfurization experiments, the desulfurization activity of the catalyst cound still reach 90.6 %, indicating that the catalyst had good cyclic stability, which was closely connected to the hydrophobicity of the -F atom. The introduction of -F atom improved the hydrophobicity of the catalyst so that the generated sulfone was not easy to be adsorbed on the active site and improved the cyclic stability of the catalyst. Furthermore, the increase in the number of Mo active species was important in improving the cyclic stability of the catalyst.
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