Hydrodeoxygenation Of Anisole Research Articles

Effect of Zn on performance of Ni/SiO2 for hydrodeoxygenation of anisole

Herein, SiO2 supported metallic Ni (Ni/SiO2) and bimetallic Ni-Zn (NixZn/SiO2) (x represents the Ni/Zn atomic ratio) catalysts were prepared by the incipient wetness impregnation method and their activities were tested in vapor phase hydrodeoxygenation (HDO) of anisole under 0.1 MPa. The characterization results show that Ni-Zn alloy forms in NixZn/SiO2 after reduction at 550 °C, and a suitable Ni/Zn atomic ratio (30) leads to smaller alloy particle size and consequently more H2 adsorption amount than others. In the HDO reaction, the formation of Ni-Zn alloy facilitates the direct deoxygenation pathway and suppresses CO methanation and C−C bond hydrogenolysis, which is ascribed to the isolation effect of the Ni atoms by the oxophilic Zn ones. Ni30Zn/SiO2 gives not only higher anisole conversion but also higher selectivity to benzene than Ni/SiO2. Therefore, the introduction of a suitable amount of oxophilic Zn in Ni/SiO2 promotes the HDO of anisole to benzene. Finally, we propose that the Ni30Zn/SiO2 deactivation is related to the oxidation of Ni-Zn alloy and carbon deposition on the catalyst surface.

Oxygen Healing and CO2 /H2 /Anisole Dissociation on Reduced Molybdenum Oxide Surfaces Studied by Density Functional Theory.

Reduced molybdenum oxides are versatile catalysts for deoxygenation and hydrodeoxygenation reactions. In this work, we have performed spin-polarized DFT calculations to investigate oxygen healing energies on reduced molybdenum oxides (reduced α-MoO3 , γ-Mo4 O11 and MoO2 ). We find that Mo+4 on MoO2 (100) is the most active for abstracting an oxygen from the oxygenated compounds. We further explored CO2 adsorption and dissociation on reduced α-MoO3 (010) and MoO2 (100). In comparison to reduced α-MoO3 (010), CO2 adsorbs more strongly on MoO2 (100). We find that CO2 dissociates on MoO2 (100) via a two-step process, the overall barrier for which is 0.6 eV. This barrier is 1.7 eV lower than that on reduced α-MoO3 (010), suggesting a much higher activity for deoxygenation of CO2 to CO. As H2 dissociation is shown to be the rate-limiting step for hydrodeoxygenation reactions, we also studied activation barriers for H2 chemisorption on MoO2 (100). We find that the chemisorption barriers are 0.7 eV lower than that reported on reduced α-MoO3 (010). Finally, we have studied the dissociation (C-O cleavage) of anisole (a lignin-based biofuel model compound) on MoO2 (100). We find that anisole binds very strongly on MoO2 (100) with an adsorption energy of -1.47 eV. According to Sabatier's principle, strongly adsorbing reactants poison the catalyst surface, which may explain the low activity of MoO2 observed during experiments for hydrodeoxygenation of anisole.

Enhanced selective cleavage of aryl C-O bond by atomically dispersed Pt on α-MoC for hydrodeoxygenation of anisole

Hydrodeoxygenation (HDO) is an important catalytic route for upgrading of biomass resources to biofuels. The cleavage of aryl C-O bond is the key step to remove oxygen atoms from biomass molecules, however, which usually occurs after the cleavage of alkyl C-O bond in thermodynamics due to the significant higher bond energy of aryl C-O bond. Herein, we report a series of Pt/α-MoC catalysts with different Pt concentration for the HDO of anisole, a biomass molecule. The Pt/α-MoC catalyst exhibits enhanced HDO catalytic performance in terms of the higher turnover rate (150.2 h−1) and lower apparent activation energy (42.5–48.2 kJ·mol−1) compared with primitive α-MoC catalyst. By temperature programmed surface reaction and X-ray absorption spectrum, the status of Pt in the Pt/α-MoC catalyst is revealed to be atomically dispersed on α-MoC when the Pt/Mo ratio is lower than 0.2 %. The singly dispersed PtMo bimetallic sites serve as the catalyst for HDO, and attribute to the dissociation of aryl C-O bond prior to that of alkyl C-O bond. This work identifies the role of Pt in the carbide catalyst for HDO, and further provides new insight for catalyst design towards to selective C-O bond cleavage.

An efficient bifunctional Ni-Nb2O5 nanocatalysts for the hydrodeoxygenation of anisole

The anisole is almost completely transformed into cyclohexane by the synthesized Ni-Nb 2 O 5 nanocatalysts following the HYD reaction route. The Ni-Nb 2 O 5 nanocatalysts have been prepared by the sol–gel method, and the catalytic hydrodeoxygenation (HDO) performance of anisole as model compound is studied. The results show that Nb exists as amorphous Nb 2 O 5 species, which can promote Ni dispersion. The addition of Nb 2 O 5 increases the acidity of the catalyst. However, when the content of niobium is high, there is an inactive Nb-Ni-O mixed phase. The size and morphology of Ni grains in catalysts are different due to the difference of Nb/Ni molar ratio. The Ni 0.9 Nb 0.1 sample has the largest surface area of 170.8 m 2 ·g −1 among the catalysts prepared in different Nb/Ni molar ratios, which is mainly composed of spherical nanoparticles and crack pores. The HDO of anisole follows the reaction route of the hydrogenation HYD route. The Ni 0.9 Nb 0.1 catalyst displayed a higher HDO performance for anisole than Ni catalyst. The selectivity to cyclohexane over the Ni 0.9 Nb 0.1 sample is about 10 times that of Ni catalyst at 220 °C and 3 MPa H 2 . The selectivity of cyclohexane is increased with the increase of reaction temperature. The anisole is almost completely transformed into cyclohexane at 240 °C, 3 MPa H 2 and 4 h.

Optimization of operating conditions for anisole hydrodeoxygenation reaction over Zr-based metal–organic framework supported Pt catalyst

To optimize the operating conditions for catalytic hydrodeoxygenation (HDO) of anisole in a continuous fixed-bed reactor, the response surface methodology combined with the central composite design was used to maximize the conversion by tuning the molar ratio of H2 to anisole, temperature, and pressure, which are considered key parameters on catalytic reaction. Analysis of variance was used to determine the regression model's compatibility. The catalyst was prepared using a Zr-based metal–organic framework, UiO-67, as a support, which was synthesized under microwave-assisted solvothermal reaction, followed by loading Pt nanoparticles on its surface via a double solvent method. The results demonstrated that the obtained mathematical model accurately predicted the conversion, which was more greatly influenced by temperature in comparison with the H2/anisole molar ratio and pressure in HDO reaction over the 3 wt% Pt/UiO-67 catalyst. Concurrently, the highest conversion of 92.5% was obtained under the optimum conditions: H2/anisole molar ratio of 35.2, reaction temperature of 297.6 °C, and a reaction pressure of 12.8 bar. The relative error was only 1.08% when compared with experimental values obtained under near-optimum conditions. Furthermore, at high temperatures, the reaction pathway followed the demethoxylation trend, yielding cyclohexane and benzene as the main products.

In-situ studies on the synergistic effect of Pd-Mo bimetallic catalyst for anisole hydrodeoxygenation

Bimetallic catalyst is a major group of the heterogeneous catalysts which has been widely investigated for many important catalytic processes such as biomass upgrading. The synergistic effect between two transition metal of bimetallic catalyst plays a vital role to promote catalytic performance. In this work, the Pd-Mo bimetallic catalysts were investigated for the hydrodeoxygenation (HDO) of a biomass-derived molecule, anisole. The synergistic effect was confirmed in the Pd-Mo bimetallic catalyst. The correlated structure features of the Pd and Mo sites during catalysis have been revealed to understand the synergistic effect. It is found that the Mo species are partially reduced and cover around Pd nanoparticles. As the results, the crystalline status, redox properties, electron state and adsorption behaviors of Pd species are greatly influenced by Mo species. Moreover, the formation of Pd-Mo bond is directly observed by in-situ X-ray absorption spectrum. This work brings new insights to understand the structure origination for the synergistic effect in bimetallic catalyst.

High-loaded Ni-based catalysts obtained via supercritical antisolvent coprecipitation in transfer hydrogenation of anisole: Influence of the support

Transfer hydrogenation of anisole in 2-PrOH has been studied as a model reaction for lignocellulose processing. The reaction was studied over high-loaded Ni-based catalysts synthesized via supercritical antisolvent precipitation of a Ni precursor and sols of four oxides: Al2O3, SiO2, TiO2, and ZrO2. It was demonstrated that the oxide support significantly affects the structure of the catalysts, their activity, and selectivity. The best performance in the transfer hydrodeoxygenation of anisole was shown by Ni supported on alumina at 250 °C, which was explained by the highest dispersion of Ni0 particles in this catalyst and by the highest concentration of acid centers.

Anisole Hydrodeoxygenation: A Comparative Study of Ni/TiO2-ZrO2 and Commercial TiO2 Supported Ni and NiRu Catalysts

Anisole Hydrodeoxygenation: A Comparative Study of Ni/TiO2-ZrO2 and Commercial TiO2 Supported Ni and NiRu Catalysts

Regulating electronic environment on alkali metal-doped Cu@NS-SiO2 for selective anisole hydrodeoxygenation

Lignin utilization is a potential approach for replacing fossil energy and releasing the environment pressure. Herein, we synthesized a series of novel Cu-based catalysts, Cu@NS-SiO2 (NS = nano sphere) and alkali metals (Na, K, Rb, and Cs) doped Cu@NS-SiO2, and applied them in hydrodeoxygenation reaction of anisole. High Cu dispersion was presented on all catalysts. The modification of alkali metals on Cu@NS-SiO2 significantly enhanced the electron density of Cu sites in the following order: Cs > Rb > K > Na, among which Cs decreased the Cu 2p3/2 binding energy most (by 0.7 eV). Moreover, the modification did not substantially affect the geometric structure of Cu species. This regulable electronic environment of Cu sites was crucial for selective deoxygenation and inhibiting the hydrogenation of aromatic rings in anisole, and thus promoted the selectivity of benzene. Compared with Cu@NS-SiO2 (∼59%), the highest benzene selectivity was obtained on Cs/10Cu@NS-SiO2 at ∼83%.

Boosting the Ni‐Catalyzed Hydrodeoxygenation (HDO) of Anisole Using Scrap Catalytic Converters

AbstractThe large availability and renewable nature of lignin makes its upgrading to bioproducts of particular interest for sustainable development. The hydrodeoxygenation (HDO) of anisole specifically represents a model reaction for the conversion of lignin to biofuels through the removal of the aromatic carbon‐oxygen bonds. To date, a range of Ni‐based catalysts have been reported as highly active systems for the HDO of anisole. However, there has been a substantial lack of consideration given to the environmental characteristics of these catalytic systems, in contrast with the scope of the sustainable production of biofuels. Herein, Ni‐based SiO2 catalysts are prepared by a solventless and highly efficient mechanochemistry approach, having a considerably lower environmental impact as compared to standard impregnation methods. Importantly, scrap catalytic converters (SCATs) are employed as co‐catalysts, proving the possibility of enhancing the catalytic HDO of anisole, with a scarcely exploited waste material. The results demonstrate that the combined use of Ni/SiO2 as catalysts and Ni/SCATs as co‐catalysts remarkably boosts the rate of the conversion of anisole up to more than 50% by achieving an almost complete conversion of anisole in only 40 min instead of at 200 °C and 4 MPa H2.

Impact of oxygen vacancies in Ni supported mixed oxide catalysts on anisole hydrodeoxygenation

The hydrodeoxygenation (HDO) activity of anisole has been investigated over Ni catalysts on mixed metal oxide supports containing NbZr and TiZr in 1:1 and 1:4 ratios. XRD patterns indicate the incorporation of Ti (or Nb) into the ZrO2 framework. XPS and oxygen pulse chemisorption analyses reveal that Ni/Ti1Zr4 and Ni/Nb1Zr4 possessed more oxygen vacancy sites than Ni/Ti1Zr1 and Ni/Nb1Zr1, respectively. Correspondingly, the HDO activity of Ni/Ti1Zr4 and Ni/Nb1Zr4 was higher with an anisole conversion up to 30.7 and 34.4%, with high selectivity towards benzene (up to 64.7 and 63.3%), compared to corresponding Ni/Ti1Zr1 and Ni/Nb1Zr1 catalysts.

Synergies of surface-interface multiple active sites over Al-Zr oxide solid solution supported nickel catalysts for enhancing the hydrodeoxygenation of anisole

Currently, the catalytic hydrodeoxygenation (HDO) of oxygen-containing compounds derived from biomass to highly valuable chemicals or hydrocarbon bio-fuels is attracting more and more attention. Concerning the design and synthesis of high-performance supported metal catalysts for HDO, the efficient deposition/immobilization of active metal species on supports, as well as the construction of the favorable properties of supports, is quite necessary. In this work, we fabricated series of aluminum-zirconium oxide solid solution supported Ni-based catalysts by a simple surfactant-assisted homogeneous coprecipitation and applied them in the HDO of anisole. Various structural characterizations showed that surface-interface properties of Ni-based catalysts (i.e., surface acidity, defective structures, and metal-support interactions) could be finely tuned by adjusting the amount of Al introduced into Al-Zr oxide solid solutions, thus profoundly governing their catalytic HDO activities. It was demonstrated that the introduction of an appropriate amount of Al could not only enhance surface acidity and promote the formation of defective Zr-Ov-Al structures (Ov: oxygen vacancy) but also facilitate the generation of interfacial Niδ+ species bound to the support. Over the Ni-based catalyst bearing an Al2O3:ZrO2 mass ratio of 5:2, a high cyclohexane yield of ∼77.4% was attained at 230 °C and 1.0 MPa initial hydrogen pressure. The high catalytic HDO efficiency was revealed to be correlated with the catalytic synergy between Ni0 and adjacent interfacial Niδ+ species, together with the promotion of neighboring defective oxygen vacancies and acidic sites, which contributed to the enhanced activation of the methoxy group in anisole and reaction intermediate and thus greatly improved HDO activity. The present findings offer a new and promising guidance for constructing high-performance metal-based catalysts via a rational surface-interface engineering.

Anisole hydrodeoxygenation over Ni-Co bimetallic catalyst: a combination of experimental, kinetic and DFT study.

Catalytic hydrodeoxygenation (HDO) of anisole was performed with a series of Ni and Co containing catalysts with different weight ratios on activated carbon (AC) for cyclohexanol production. The catalytic activities of various catalysts revealed that Ni5Co5-AC was the best catalytic system. Structural analysis obtained from XRD, TPR, XPS, and TEM evidently demonstrates that Ni5Co5-AC sample consists of a distorted metal alloy spinel structure and optimum particle size, enhancing its catalytic performance. Kinetics were investigated to identify cyclohexanol production rate, activation energy, and reaction pathway. Structural, experimental, kinetics and density functional simulations suggested that high amount of distorted metallic alloy in Ni5Co5-AC, presence of water, high adsorption efficiency of anisole, and low adsorption tendency of cyclohexanol on metallic alloy surface were the critical factors for HDO of anisole to cyclohexanol.

The role of Ni sites located in mesopores in the selectivity of anisole hydrodeoxygenation

A highly dispersed Ni catalyst with an increased number of Ni sites selectively distributed in the mesopores of HBEA has been developed and applied in anisole hydrodeoxygenation (HDO) in a continuous-flow reactor under high WHSV (2.8 min−1).

Bimetallic Niobium-Based Catalysts Supported on SBA-15 for Hydrodeoxygenation of Anisole

The effect of adding iron, cobalt or nickel to a prepared niobium-supported catalyst using mesoporous silica SBA-15 as a support was evaluated in the hydrodeoxygenation (HDO) reaction of anisole, chosen as a model compound in lignocellulosic biomass derived bio-oil. HDO activity as well as selectivity toward O-free products were highly dependent on the catalyst formulation: Ni incorporation showed the highest anisole conversion and selectivity to deoxygenated products, followed by Co and Fe counterparts. The activity was explained in terms of acidity, metal surface exposure and reducibility as a function of the interaction between the phases present. Regarding the characterization results, the better performance of NiNb/SBA-15 was associated with its lower acidity, higher Nb/Si surface exposure, NbO2/Nb2O5 ratio and better interaction between Ni and Nb species.

Aqueous phase hydrodeoxygenation of anisole as a pyrolysis lignin-derived bio-oil by ether-functionalized ionic polymer-stabilized Ni-Mo nanocatalyst

In this study, novel nickel-molybdenum nanoparticles catalysts stabilized with ether-functionalized ionic polymer (Ni-Mo NPs@IP) were successfully synthesized and characterized by X-ray diffraction method (XRD), X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM) and transmission electron microscopy (TEM) analysis. The prepared nanocatalyst was examined in the aqueous phase catalytic hydrodeoxygenation of anisole (a model compound) on a batch reactor at 80–200 °C and 10–50 bar. The catalytic upgrading of anisole in the presence of different ratios of Ni-Mo NPs@IP includes the following: anisole conversion to phenol by hydrogenolysis, to benzene by hydrodeoxygenation, and to cyclohexane by hydrogenation. The experimental results demonstrated that the catalytic activity of Ni-Mo (50%–50%) nanoparticles stabilized with IP is superior to that with low Mo content and that raising the Mo loading by more than 50% has no discernible effect on anisole conversion. Furthermore, the results indicated that oxygen removal could be a desirable phenomenon by operating at higher temperatures, pressures, and reaction times. Furthermore, the catalytic tests under different operating conditions have indicated the superior activities of Ni-Mo NPs@IP in converting a phenolic compound into de-oxygenated fuel-grade products. The sensitivity analysis of operating condition reveals that the maximum HDO conversion is achieved over Ni-Mo (20%–80%) NPs@IP at temperature of 200 °C, hydrogen pressure of 50 bar, reaction time of 15 h and catalyst loading of 5 mol%.

MoOx-Decorated ZrO2 Nanostructures Supporting Ru Nanoclusters for Selective Hydrodeoxygenation of Anisole to Benzene

MoO_<i>x</i>-Decorated ZrO₂ Nanostructures Supporting Ru Nanoclusters for Selective Hydrodeoxygenation of Anisole to Benzene

NiAlCe mixed oxides obtained from layered double hydroxides applied to anisole hydrodeoxygenation

Bio-oil derived from the pyrolysis of lignocellulosic biomass residues cannot be used directly as biofuel due to the high content of oxygenated compounds. As an alternative, bio-oil must undergo a deoxygenation process, such as catalytic hydrodeoxygenation (HDO). In this sense, this work studied the effect of different concentrations of Ce3+ and Ce4+ in layered double hydroxides (LDHs) in order to obtain mixed oxide catalysts containing NiAlCe (NiO-NiAl2O4-CeO2) with low cost and high performance for the hydrodeoxygenation of anisole as a model bio-oil compound. Mixed oxides were obtained from the thermal decomposition of layered double hydroxides (LDHs) by using terephthalic acid as compensation anion, with molar ratio: Ni2+/(Al3++ M) = 1.0, where M = Ce3+; Ce4+ or Ce3+-Ce4+; and Al/Ce ratios of 9 and 1. Characterization analyses confirmed the formation of LDHs for all materials, although at lower Al/Ce ratio it is observed a loss of crystallinity, due to a greater repulsion and distortion of the layer structure caused by the incorporation, in greater amount, of cations with a high ionic radius. The increase in the content of cerium in mixed oxides also led to an increase in the acidity of the catalysts, in addition to a reduction in the surface area, justified by the pore blockage by CeO2 on the catalyst surface. The greater structural and thermal stability was evidenced in the LDHs derived from Ce4+, as well as a greater dispersion of the NiO phase in the corresponding mixed oxides, and therefore presenting greater anisole conversion. The obtained data indicated that the presence of Ce4+ ions on the catalyst surface was decisive in the conversion of anisole to cyclohexane, the main deoxygenated product, obtained via the direct deoxygenation and hydrogenation mechanism.

Controlled hydrodeoxygenation of lignin-derived anisole over supported Pt on UiO-66 based-catalysts through defect engineering approach

Herein, we report a series of Platinum (Pt) phase loading on the highly porous channels of the metal-organic framework (MOF) introduces open Lewis acid sites through a defective-effect, which are crucial for selective hydrodeoxygenation (HDO) process of anisole. Thereby, UiO-66 (University of Oslo) based-supports were synthesized by a microwave-assisted solvothermal method using isophthalic acid (IPA) as a mixed linker at different concentrations. The total amount of acid sites in the defective UiO-66 samples was 1.5–2.5 times higher than that of pristine UiO-66, with the corresponding linker deficiency increasing to 1.94 as the concentration of the mixed linker was increased to 30% in the starting material. Consequently, the 3Pt/defective UiO-66 catalysts achieved better catalytic performance for the anisole HDO process, with a turn-over frequency (TOF) value of the Pt site being 2–3 times higher than that of the pristine 3Pt/UiO-66. Notably, the reaction pathway shifted from producing cyclohexane to producing benzene through the demethoxylation of anisole. This resulted in an increase in the TOF value based on the benzene yield by over 10 times as the defective linker content increased from 0 to 20%. The catalytic stability was also investigated using a series of Pt/defective UiO-66 catalysts.

Selective upgrading of biomass-derived benzylic ketones by (formic acid)–Pd/HPC–NH2 system with high efficiency under ambient conditions

Selective upgrading of biomass-derived benzylic ketones by (formic acid)–Pd/HPC–NH2 system with high efficiency under ambient conditions