Hydrodeoxygenation Of Dibenzofuran Research Articles

Elucidating the Role of Ni(Pd) in Ni(Pd)-Mo2C/Carbon Catalysts for the Hydrodeoxygenation of Dibenzofuran and Bio-Oil

Elucidating the Role of Ni(Pd) in Ni(Pd)-Mo₂C/Carbon Catalysts for the Hydrodeoxygenation of Dibenzofuran and Bio-Oil

Tuning support acidity of Ni-based catalysts to improve hydrodeoxygenation activity for dibenzofuran

Controlling the oxygen-free product selectivity in catalytic hydrodeoxygenation is essential for producing high-quality fuel from coal- and biomass-derived liquids. In this paper, the selectivity of oxygen-free products and efficiency of hydrodeoxygenation of dibenzofuran as a model compound of coal- and biomass-derived liquids have been controlled by varying the Si content in the prepared catalysts (Ni/xSi-OMA, where x = SiO2/(SiO2 + Al2O3) and OMA = ordered mesoporous alumina). In comparison, the hydrodeoxygenation of dibenzofuran was performed using Ni/SBA-15, which displayed the lowest selectivity of oxygen-free products at 36.4%. On the other hand, doping Si in OMA introduces the Brønsted acid sites, which desirably enhances the selectivity of oxygen-free products. Above 99% selectivity of oxygen-free products has been attained for Ni/30Si-OMA and Ni/40Si-OMA catalysts. The Lewis acid sites of the OMA promote the deoxygenation efficiency through the enhanced adsorption of oxygen-containing intermediates. Besides, the Brønsted acid sites generated in OMA as the result of Si-doping promote the ring-opening and dehydration reactions of the oxygen-containing intermediates, which further lead to an overall enhanced hydrodeoxygenation performance for dibenzofuran.

Mechanism of dibenzofuran hydrodeoxygenation on the Ni (1 1 1) surface

• The dibenzofuran hydrodeoxygenation on Ni (1 1 1) is analyzed by DFT calculations. • The ring-opening and hydrogenation of bicyclic intermediates are competitive processes. • Decreasing the hydrogen coverage can reduce the yield of dodecahydrodibenzofuran. • The ring-opening reaction of dodecahydrodibenzofuran is challenging due to weak adsorption. The low-temperature coal tar contains a considerable number of oxygen-containing compounds, which results in poor quality. The catalytic hydrodeoxygenation of oxygen-containing compound to an added-value chemical compound is one of the most efficient methods to upgrade coal tar. In this study, density functional theory calculations are employed to assess and analyze in detail the hydrodeoxygenation of dibenzofuran, as a model compound of coal tar, on the Ni (1 1 1) surface. The obtained results indicate that dibenzofuran can be firstly hydrogenated to tetrahydrodibenzofuran and hexahydrodibenzofuran. The five-membered-ring opening reaction of tetrahydrodibenzofuran is more straightforward than that of hexahydrodibenzofuran ( E a = 0.71 eV vs . 1.66 eV). Then, both pathways generate an intermediate 2-cyclohexylphenoxy compound. One part of 2-cyclohexylphenoxy is hydrogenated to 2-cyclohexylphenol and consecutively hydrogenated to cyclohexylcyclohexanol, and another part is directly hydrogenated to cyclohexylcyclohexanone. The hydrogenated intermediates of 2-cyclohexylphenol have higher deoxygenation barriers than 2-cyclohexylphenol and cyclohexylcyclohexanol. During the hydrogenation process of cyclohexylcyclohexanone to cyclohexylcyclohexanol, the intermediate 26, formed by adding H to O atom of cyclohexylcyclohexanone, exhibits the lowest deoxygenation barrier of 1.08 eV. High hydrogen coverage may promote the hydrogenation of tetrahydrodibenzofuran, hexahydrodibenzofuran, and intermediate 26 to generate dodecahydrodibenzofuran and cyclohexylcyclohexanol. This dibenzofuran hydrodeoxygenation reaction mechanism corroborates well with previous experimental results and provides a theoretical basis for further optimization of the design of nickel-based catalysts.

Supported Pt-Ni bimetallic nanoparticles catalyzed hydrodeoxygenation of dibenzofuran with high selectivity to bicyclohexane

Catalytic hydrodeoxygenation (HDO) is one of the most effective methods to upgrade the oxygen-containing compounds derived from coal tar to valuable hydrocarbons. Herein, an efficient bimetallic catalyst Pt1Ni4/MgO was prepared and applied in the HDO of dibenzofuran (DBF). High yield (95%) of the desired product bicyclohexane (BCH) was achieved at 240 °C and 1.2 MPa of H2. Superior catalytic performance could be ascribed to the “relay catalysis” of Pt sites and Ni sites, and the reaction pathway is proposed as well. Scale-up experiment and recyclability test were also performed, which demonstrated the recyclability and promising potential application of Pt1Ni4/MgO.

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

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 ...

Stability of Mo2C/carbon catalysts during dibenzofuran hydrodeoxygenation

The stability of Mo2C/carbon catalysts was assessed for the hydrodeoxygenation (HDO) of dibenzofuran (DBF) at realistic operating conditions. Catalyst stability was determined by the degree of oxidation of the Mo2C, which in turn was determined by the Mo2C properties and the reaction conditions. Decreased Mo loading resulted in smaller Mo2C particles and faster oxidation. Increased concentration of DBF and reduced H2 pressure (4.1–2.1 MPa) increased Mo2C oxidation. The dynamic oxidation of Mo2C during HDO depended on the oxidation history of the catalyst. Oxidation of the Mo2C reduced hydrogenation activity and increased selectivity to direct deoxygenation (DDO) products. DFT analysis showed that small amounts of O did not change the preferred surface adsorption geometry of DBF on Mo2C (101). H2 dissociative adsorption was not weakened either. At 350 °C and low concentration of DBF (0.2 wt.%), the 2%Mo2C/APC catalyst was stable for >10 h.

Mechanism of Dibenzofuran Hydrodeoxygenation on the Surface of Pt(111): A DFT Study

Catalytic hydrodeoxygenation is an efficient method to upgrade the quality of low-temperature coal tar and coal liquefied oil. However, only limited researches are performed on the mechanism of hydrodeoxygenation and, therefore, innovation of more efficient and stable catalysts is less progressed and still remains a challenging subject. In this study, density functional theory calculations are carried out to get a deeper insight in the mechanism of dibenzofuran hydrodeoxygenation on the Pt(111) surface. Calculated energies and activation barriers indicate that five-membered-ring opening of tetrahydrodibenzofuran is easier than that of hexahydrodibenzofuran. Then, the generated intermediate can be preferentially hydrogenated through a non-consecutive pathway to 2-cyclohexylphenol, and would result in multiple radical species. The dehydroxylation of that intermediate formed by adding five hydrogen atoms to the phenyl ring of 2-cyclohexylphenol shows a moderate reaction barrier of 1.07 eV; whereas, dehydroxylation of cyclohexylcyclohexanol needs a higher energy barrier of 2.04 eV. For the hydrodeoxygenation of dibenzofuran on the Pt(111) surface, the target product bicyclohexane is most likely to be formed through a radical intermediate. This investigation may provide a potent theoretical guidance to design new catalyst for hydrodeoxygenation of coal to liquid.

The role of oxophilic Mo species in Pt/MgO catalysts as extremely active sites for enhanced hydrodeoxygenation of dibenzofuran

The catalytic performance of the selective hydrodeoxygenation of dibenzofuran can be controlled by the MoOx surface density and varied with the increased MoOx surface density in a volcano-shape manner.

Catalytic hydrodeoxygenation of dibenzofuran to fuel graded molecule over mesoporous supported bimetallic catalysts

The present study focuses on hydrocarbons production (bicyclohexane) from hydrodeoxygenation of dibenzofuran over Cu-Ni/Ti-MCM-41 catalysts at mild reaction conditions. The hydrodeoxygenation activity of Cu-Ni/Ti-MCM-41 catalysts was optimized via Ni loading at reaction conditions of 260 °C, 10 MPa and 6 h in batch reactor. Those loading arounds the optimum points (5–10 wt%) were characterized by TPO, RAMAN, XRD, TPR, FESEM and ICP-MS analysis. The catalytic reactions pathway for conversion of dibenzofuran to bicyclohexane were investigated using optimum catalysts (7.5 wt% Ni loading) and reaction mechanism was then proposed. The characterization results showed that Cu-Ni dispersion and catalysts reducibility decreased with continuous increment of Ni loading above 7.5 wt%. The structure activity correlation showed that the dispersion and reducibility enhanced conversions and hydrocarbons selectivity. The highest conversion of dibenzofuran (85.46%) and selectivity of bicyclohexane (58.77%) were found with 7.5% Ni loading. Further addition of Ni loading could lead to decreasing of both activity and selectivity due to poor dispersion and agglomeration as well as low reducibility as Ni loading crossed the optimum points. The product distribution study indicated that the presence of other by-product such as cyclohexyl-benzene, tetra-hydro-dibenzofuran, cyclohexyl-cyclohexanol, cyclohexyl-cyclohexanone, 1-cyclohexyl-cyclohexene, 2-cyclohexyl-phenol. The proposed reaction mechanisms showed that the conversion of dibenzofuran was initiated by partial hydrogenations followed by deoxygenations and subsequently dehydrated to bicyclohexane.

Insights into the reaction pathway of hydrodeoxygenation of dibenzofuran over MgO supported noble-metals catalysts

Conversion of oxygen-containing compounds derived from lignin arises wide interest due to fossil-derived resources consumption and growing environmental concerns. In this work, hydrodeoxygenation (HDO) of dibenzofuran (DBF) was studied over high-surface-area MgO supported Pt, Pd and Ru catalysts at 370 °C and 1.0 MPa. It was determined that the active metals not only affect the catalytic activity, but also change the reaction pathway of HDO of DBF. The intrinsic activity (TOF) of MgO supported catalysts follows the trend: Pt/MgO (0.36 s−1) > Ru/MgO (0.29 s−1) > Pd/MgO (0.09 s−1), companied by the increasing activate barrier. Pt has a high activity in the hydrogenation of DBF, and exhibits a perfect deoxygenation activity followed by hydrogenation (HYD) pathway. Ru shows better cleavage ability of CaromaticO bond and the removal of oxygen from DBF mainly occurs via direct deoxygenation (DDO) pathway. The increased Pt loadings largely promote the conversion of DBF by enhancing both HYD and DDO pathways. In addition, more direct cleavage of CaromaticO bond occurs at higher temperature and the production of aromatics by the DDO pathway prefers the relatively low reaction pressure. Based on the pseudo-first-order kinetics, the analysis of the fitted reaction rate constant shows that the DDO selectivity follows the order: Ru/MgO > Pd/MgO > Pt/MgO, which depends on the capacity of active metals to the cleavage of CaromaticO bond and the hydrogenation of aromatic ring.

Hydrodeoxygenation of dibenzofuran to bicyclic hydrocarbons using bimetallic Cu–Ni catalysts supported on metal oxides

This work reports hydrodeoxygenation of dibenzofuran into bicyclic hydrocarbons over Cu–Ni catalysts supported on TiO2, ZrO2 and CeO2. The supported Cu–Ni catalysts were synthesized using a wet-impregnation method and calcined and reduced at 500°C in accordance with TGA, DSC, and H2-TPR results. The catalyst properties were systematically examined using Raman, XRD, SEM, EDX and XPS techniques. XRD and Raman studies reveal the existence of cubic phase CeO2, monoclinic ZrO2, anatase TiO2, and cubic NiO in the synthesized catalysts. H2-TPR results show the simultaneous reduction of Cu2+ to Cu0 and Ni2+ to Ni0, forming bimetallic Cu–Ni alloy. Among the supports, a high dispersion of Cu–Ni particles was found on the CeO2 support, as evidenced by SEM studies. The reduced catalysts were investigated for hydrodeoxygenation of dibenzofuran at 250, 260 and 270°C at 100 H2 bar for 6h. The results show that the conversion of dibenzofuran increases with the increase of temperature: at 250 and 260°C CuNi/TiO2 catalyst showed higher dibenzofuran conversions of 96% and 99% than the NiCu/CeO2 catalyst with relatively low conversions of 89% and 98%, respectively. In contrast, low conversions of 63% and 68% were found for the CuNi/ZrO2 catalyst under identical reaction conditions. In the case of selectivity to hydrocarbons, NiCu/TiO2 catalyst showed excellent selectivity to bicyclohexyl compared with that of NiCu/CeO2 and NiCu/ZrO2 catalysts at 260°C. However, in terms of selectivity to bicyclohexyl-1-ene, NiCu/CeO2 catalyst showed the highest selectivity at 250°C, while NiCu/ZrO2 catalyst exhibited the highest selectivity at 260 and 270°C.

Effective hydrodeoxygenation of dibenzofuran by a bimetallic catalyst in water

Hydrodeoxygenation of dibenzofuran by Ni/Pt bimetallic catalyst was achieved with 99% total conversion and 88% of selectivity of cyclohexylbenzene.

Promising Ni/Al-SBA-15 catalysts for hydrodeoxygenation of dibenzofuran into fuel grade hydrocarbons: synergetic effect of Ni and Al-SBA-15 support

First time application of Al-SBA-15 supported Ni catalysts for hydrodeoxygenation of dibenzofuran to hydrocarbons was investigated in this study.

Hydrodeoxygenation of dibenzofuran over SiO2, Al2O3/SiO2and ZrO2/SiO2supported Pt catalysts

Highly dispersed platinum nanoparticles are supported on Al2O3or ZrO2modified silica for hydrodeoxygenation of dibenzofuran.

Hydrodeoxygenation of Dibenzofuran Over SBA-15 Supported Pt, Pd, and Ru Catalysts

Hydrodeoxygenation (HDO) of dibenzofuran (DBF) has been carried out over mesoporous silica SBA-15 supported Pt, Pd, and Ru catalysts. The HDO of DBF went through hydrogenation of aromatic rings first, followed by hydrogenolysis of the saturated C–O bond to produce hydrocarbons. The detection of intermediate 2-cyclohexylcyclohexanol over as-prepared Pt catalysts illustrated that the aromatic ring-containing hydrogenated species transformed to the major deoxygenated product bicyclohexane after elimination of the heteroatom oxygen. Among all three catalysts, the Pt/SBA-15 catalysts exhibited the highest hydrogenation activity to yield aromatic ring-containing hydrogenated products. However, the Ru catalysts were more efficient in formation of completely deoxygenated products. Meanwhile, more cleavage of the saturated C–O bond took place at higher reaction temperature in the HDO of DBF. The increase of hydrogen pressure promoted the saturation of aromatic rings with an obvious influence on the conversion of DBF.

Hydrodeoxygenation of Dibenzofuran over Mesoporous Silica COK-12 Supported Palladium Catalysts

Hydrodeoxygenation (HDO) of dibenzofuran (DBF) with only a hydrogenation (HYD) reaction route was conducted on Pd/COK-12 catalysts with different Pd loadings, which were prepared by metal–organic chemical vapor deposition of [Pd(C3H5)(C5H5)] onto mesoporous silica COK-12. Hydrogenated intermediates with partial or full hydrogenation of the benzene ring were studied in detail. The presence of cycloketones is due to the high selectivity of Pd-based catalysts in the hydrogenation of phenols derived from the C–O bond cleavage of hydrogenated intermediates. The reaction only goes through the HYD reaction route with hardly detected biphenyl, which is further confirmed by HDO of 2-phenylphenol. The increase of Pd loading on the catalysts largely promotes the deoxygenation of saturated oxygen-containing species from hydrogenation of DBF, followed by cleavage of the sp3 C–O bond. Finally, a detailed reaction network of HDO of DBF is proposed according to the detected hydrogenated species and cycloketones.

Oxygen-removal of dibenzofuran as a model compound in biomass derived bio-oil on nickel phosphide catalysts: Role of phosphorus

The hydrodeoxygenation (HDO) of dibenzofuran (DBF) was investigated over silica-supported nickel phosphide catalysts with low metallic loadings (2.5–10wt.%) and with different initial P/Ni atomic ratios. The formation of the nickel phosphide phase as well as the textural, structural and acidic properties of the catalysts were evaluated by X-ray fluorescence (XRFS), H2-temperature programmed reduction (H2-TPR), X-ray diffraction (XRD), CO chemisorption at 35°C, N2 adsorption–desorption isotherms at −196°C, NH3-temperature programmed desorption (NH3-TPD) and elemental analysis (CNHS). The effect of metallic loading, the initial P/Ni molar ratio as well as the feed O-concentration on the catalytic activity were studied. Characterization results reveal that smaller particle sizes are formed at lower metallic loadings and high P/Ni atomic ratios, and that the acidity increases linearly with the metallic loading pointing to nickel and phosphorous species as the acidic centers in reduced catalysts. Nickel phosphide catalysts display good activity and stability in the HDO of DBF, reaching high DBF conversion values at moderate temperatures (300°C) and with high selectivity to bicyclohexane (BCH), the main deoxygenated product which was obtained by hydrogenation of both aromatic rings (HYD pathway). Catalyst deactivation due to coke was minimal due to the low strength of the acid sites, while the formation of water did not present an inhibiting effect even under high O-concentration. This behavior might occur because water interacts preferentially with the excess phosphorous present on the catalyst surface and thus nickel phosphide particles do not undergo oxidation.

Hydrodeoxygenation of dibenzofuran over noble metal supported on mesoporous zeolite

Hydrodeoxygenation has been considered to be one of the most promising methods for bio-oil upgrading. in this paper, the catalytic performance of noble metal supported on mesoporous zeolite in model bio-oil compound hydrodeoxygenation was examined. Dibenzofuran was chosen here because of its refractory nature and large molecular size. Our results indicate that Pt supported on mesoporous ZSM-5 show better performance in dibenzofuran hydrodeoxygenation than Pt/ZSM-5 and Pt/Al(2)O(3). The excellent catalytic performance is attributed to the combination of strong acidity and mesopore structure in mesoporous zeolite. (C) 2011 Elsevier B.V. All rights reserved.

Control of Dealkylation vs Ring Hydrogenation by Use of Ammonia

Hydrotreating studies with propylbenzene as a model compound on a commercial NiMo/Al 2 O 3 catalyst at 300-360 °C and 6.9 MPa showed that selectivity to ring hydrogenation vs dealkylation was increased by addition of ammonia at partial pressures up to 49 kPa, although overall activity decreased. Both reactions followed first-order kinetics. Selectivity was markedly increased at the lowest temperatures but again was accompanied by the lowest overall activity. The poisoning effect of ammonia here is much greater than that previously observed on hydrodesulfurization of thiophene or hydrodeoxygenation of dibenzofuran under identical reaction conditions

Hydrogen transfer promoted ring growth during catalytic resid hydroprocessing

A model feedstock consisting of dibenzothiophene, dibenzofuran, quinoline, and phenanthrene dissolved in heptane has been hydroprocessed in a flow reactor at 6.89 MPa and 400 °C over a series of nickel-molybdate catalysts. Under simultaneous processing, the main product of dibenzothiophene hydrodesulphurization was diphenyl, the main product of quinoline hydrodenitrogenation was propylcyclohexane, and that of dibenzofuran hydrodeoxygenation was cyclohexyl benzene. Sulphur was removed without the need for saturation of the sulphur-containing ring. For both nitrogen and oxygen removal, the ring containing the hetero atom was saturated before scission of the CN or CO bond. The main products of the hydroprocessing of phenanthrene were hydroderivatives of varying degrees of saturation. Very little hydrocracking took place under our conditions, and this occurred predominantly by successive saturation and cracking of terminal rings. With increasing catalyst acidity, the rates of all reactions studied increased, as did the degree of hydrocracking relative to hydrogenation. Coke formation on the catalyst also increased markedly with acidity.