Hydrodeoxygenation Of 4-methylphenol Research Articles

Selective breaking of C−O bonds in hydrodeoxygenation of 4-methylphenol over CoMoS/ZrO2

CoMoS/ZrO2 catalysts with different Co-Mo atomic ratios (0.25, 0.30, 0.35, 0.40 and 0.45) and Co-Mo loading amounts (2.35%, 4.36%, 7.48% and 10.79%) were prepared by incipient wetness impregnation. These catalysts were characterized by X-ray diffraction (XRD), temperature-programmed reduction (H2-TPR), nitrogen adsorption/desorption and X-ray photoelectron spectroscopy (XPS). 4-methylphenol was used as model compound for hydrodeoxygenation reaction. The result showed that when the atomic ratio of Co-Mo (Co/Co + Mo) was 0.30 and the Mo loading amount was 4.36%, the highest hydrogenation activity was observed. The conversion of 4-methylphenol was up to 99.86% and the selectivity of main product toluene reached to 87.85%. The formation of CoMoO4 was unfavourable to the formation of toluene. An appropriate interaction between Co-Mo and ZrO2 was required.

Correlation of the catalytic performance with Nb2O5 surface properties in the hydrodeoxygenation of lignin model compound

Production of aromatic hydrocarbons through lignin hydrodeoxygenation (HDO) is of significant importance. Previously, we found that Ru/Nb2O5 was an excellent catalyst for the conversion of lignin to arenes with relatively high selectivity (71%). Herein, we aim to clarify which properties of Nb2O5 influence the activity and selectivity. Four Ru/Nb2O5 catalysts with different Nb2O5 morphologies were used in the HDO of 4-methylphenol. Intensive studies show that layered Nb2O5 supported Ru has more NbO groups (unsaturated NbOx sites) and highest Ru dispersion, which led to the highest activity and toluene selectivity, this was further confirmed by loading pre-synthesized Ru colloids in various Nb2O5. Finally, a Ru/Nb2O5 catalyst with more unsaturated NbO groups was designed and it was found that even with enzymatic lignin as the feedstock, the selectivity to arenes can reach up to 94.8% with the yield of hydrocarbons of 99.6%. This study provides a promising strategy for catalyst design towards the selective production of aromatic hydrocarbons from lignin.

Hydrazine-Assisted Liquid Exfoliation of MoS2 for Catalytic Hydrodeoxygenation of 4-Methylphenol.

A simple but effective method to exfoliate bulk MoS2 in a range of solvents is presented for the preparation of colloid flakes consisted of one to a few molecular layers by application of ultrasonic treatment in N2 H4 . Their high yield in solution and exposure of more active surface sites allows the synthesis of corresponding solid catalysts with remarkably high activity in hydrodeoxygenation of 4-methylphenol and this method can also be applied to other two dimensional materials.

Slurry-Phase Batch Microreactor for Hydroconversion Studies

A novel microreactor that allows for mixed, slurry-phase batch experiments to be conducted at temperatures to 445 °C and pressures of 13.8 MPa is reported. The reactor uses a glass insert to isolate the reaction mixture from the catalytically active reactor walls and a vortex mixer to promote gas–liquid–solid mixing and requires only 150 μL of reaction mixture to operate. The rapid heating and cooling (to 445 °C and back to room temperature in under 30 min) afforded by the small size makes this reactor ideal for fast catalyst-screening studies. The utility of the reactor is demonstrated through a study of the hydroconversion of diphenylmethane (DPM) at 445 °C and 13.8 MPa and the hydrodeoxygenation of 4-methylphenol (4-MP) at 375 °C and 4.8 MPa, both conducted using an unsupported MoS2 catalyst. A high-speed video is used to identify 2000 rpm as the optimum mixing speed for the microreactor. Conversion data for DPM and 4-MP in the microreactor is used to determine rate constants for the reactions and, hence, quantify MoS2 catalytic activity and thermal/reactor wall activity. The MoS2 activity is found to be in good agreement with published stirred batch reactor results using the same catalyst.

Influence of Surfactants on the Synthesis of MoS2 Catalysts and Their Activities in the Hydrodeoxygenation of 4-Methylphenol

MoS2 catalysts were synthesized by hydrothermal method using ammonium heptamolybdate and thiocarbamide as materials, focusing on the effects of the addition of surfactants (such as hexadecyltrimethylammonium bromide, polyvinylpyrrolidone, and sodium lauryl benzenesulfate) during the MoS2 catalyst preparation on their structure and activity in the hydrodeoxygenation (HDO) of 4-methylphenol. The addition of surfactant not only increased the surface area of MoS2, but also changed its microstructure in the stack layer. Compared with Mo—S prepared without any surfactant, Mo—S—DB, Mo—S—CT, and Mo—S—PV exhibited higher activity in the HDO of 4-methylphenol. According to the characterization and catalytic activity results, the structure–activity relation was revealed, and the HDO mechanism of 4-methylphenol on these catalysts was well illustrated by the Rim–Edge model. The HDO of 4-methylphenol on these MoS2 catalysts proceeded with two parallel routes (HYD and DDO), and their selectivity depended on its layer nu...

Effect of W addition on the hydrodeoxygenation of 4-methylphenol over unsupported NiMo sulfide catalysts

Unsupported NiMo sulfide catalysts modified by tungsten were prepared by a mechanical activation method. They were characterized by XRD, XPS, SEM, TEM and BET specific surface area measurements. The effect of tungsten promoter on the structure and catalytic performance was also discussed. The present work suggested that the addition of tungsten could greatly enhance the hydrodeoxygenation (HDO) activity, and promote the direct deoxygenation (DDO) pathway. Moreover, the addition content affects the mount of active NiMo(W)S phase, resulting in various functions.

The effect of nickel content on the hydrodeoxygenation of 4-methylphenol over unsupported NiMoW sulfide catalysts

Abstract Unsupported NiMoW sulfide hydrodeoxygenation (HDO) catalysts were prepared by mechanical activation method varying the nickel concentration. Catalysts were characterized by XRD, SEM, TEM and BET surface area measurements. Moreover, catalytic activity and selectivity were evaluated in the HDO of 4-methylphenol (4-MP). The results suggested that the structure and the promoting effects were strongly dependent on the amount of Ni added into the catalysts. Nickel gave a positive effect on HDO of 4-MP and modified the product selectivity slightly. It was also found that nickel played a crucial role in the variation of catalytic performance.

Hydrodeoxygenation of 4-Methylphenol over Unsupported MoP, MoS2, and MoOx Catalysts

A study of the hydrodeoxygenation (HDO) of 4-methylphenol over unsupported, low-surface-area MoS2, MoO2, MoO3, and MoP catalysts is reported. With the exception of MoO3, the catalysts had the same physicochemical properties before and after the 5 h reaction at 623 K and 4.40 MPa H2. The used MoO3 was partially reduced to a mixed oxide containing Mo4O11, MoO2, and Mo. Compared to the unused MoO3, the used MoO3 CO uptake increased by a factor of 100 following the reaction. The partially reduced Mo oxide catalyst had a high conversion for the HDO of 4-methylphenol because of Bronsted acid sites and the formation of anionic vacancies. The catalyst turnover frequency (TOF) based on CO uptake for the HDO of 4-methylphenol decreased in the order MoP > MoS2 > MoO2 > MoO3, while the activation energy increased in the order of MoP < MoS2 < MoO2 < MoO3. The activity trends correspond to the increased electron density of the Mo among the catalysts. Two primary reactions, C−O hydrogenolysis to yield toluene and satura...