Lignin-derived Bio-oil Research Articles

Investigation of ruthenium loaded beta zeolite catalyst performance in vanillin hydrodeoxygenation yielding both monomeric and dimeric cycloalkanes

The valorization of lignin-derived bio-oil is studied extensively due to its promising contribution to sustainability. Among these studies, many have focused on the hydrodeoxygenation (HDO) of phenolic model compounds as it is a crucial process in obtaining valuable oxygen-free hydrocarbons. In this work, vanillin HDO was performed on various bifunctional ruthenium-based zeolite catalysts with different zeolite supports (Y, ZSM-5, and beta) in a batch reactor. Ru-loaded beta zeolite catalysts (Ru/Hβ) exhibited the highest HDO activity among them, and the formation of dimeric cycloalkanes of high value were also observed specifically when using the Ru/Hβ catalyst. Due to their benefits of direct use in blending of biofuel, factors promoting the dimerization of phenolic monomers were extensively examined through a series of experiments using a mix of phenolic model compounds as HDO reactants. Specific oxygen containing functional groups contributed to the aldol condensation of aromatic species, and the structure and kinetic diameter of the monomers had a profound effect on the ability to participate in dimerization. Additionally, the metal loading of the catalyst and reaction conditions such as temperature and hydrogen pressure were varied to observe each of their effects on the product distribution. The change in metal loading had a remarkable impact on the preferred reaction pathway and product selectivity, while a high temperature of 200 °C and hydrogen pressure of 50 bar was determined to be necessary to fully achieve HDO to cycloalkanes. Consequently, this study has provided useful information on the production of both monomeric and dimeric cycloalkanes and has contributed to the development of the bio-oil upgrading process.

N-doped MOF-lignin hybrid catalyst for highly selective hydrodeoxygenation of lignin-derived phenols

Upgrading of lignin-derived bio-oil to value-added biofuel was of great significance for efficient utilization of renewable resources and reducing the use of fossil fuels. Hydrodeoxygenation (HDO) was considered to be a promising technology for the conversion of lignin-derived bio-oil. Herein, we reported a novel method for the preparation of lignin-MOF derived N-doped catalysts, which was then successfully introduced into the upgrading of lignin-derived phenols and lignin depolymerization. All catalysts were well characterized and Co/CN-0.5–750 exhibited excellent performance during the catalytic HDO process. The optimized catalyst demonstrated highly efficient active hydrogen generation from isopropanol. Moreover, it could afford the best vanillin (VAN) conversion (100 %) and highest 2-Methoxy-4-methylphenol (MMP) yield (92 %) under the mild reaction conditions (180 °C, 0.5 MPa nitrogen, 2 h). It was confirmed that the excellent performance was related to nitrogen doping. This study could provide some useful insights for the hydrodeoxygenation of lignin and its derivative.

Melt infiltration for the preparation of finely dispersed Ni-FeOx nanoparticles on SBA-15 for the hydrodeoxygenation of m-cresol

The polymer-assisted melting infiltration method was used to finely disperse Ni, Fe and bimetallic Ni-Fe precursors in ordered mesoporous SBA-15 support. This approach allowed to obtain small Ni nanoparticles, in the order of 2 nm in size, with finely dispersed iron oxide surrounding metallic Ni, without evidence of Ni-Fe alloy formation. The catalysts were used in the HDO reaction of m-cresol at 300 °C and atmospheric pressure. The conversion of m-cresol was found to be dependent on Ni content, with the total reaction rate decreasing when Ni is partially replaced by iron. Toluene was the main product obtained for both, mono Ni and bimetallic Ni-Fe catalysts, thus suggesting that nickel nanoparticles when in the form of small sized particles, are the active sites for deoxygenation, independent on the presence of oxophilic iron site in their proximity. Such findings will serve for the further design of effective catalysts for the upgrading of lignin-derived bio-oil.

LiCoO2 impregnated nano-hierarchical ZSM-5 assisted catalytic upgrading of Kraft lignin-derived liquefaction bio-oil.

In this study, Kraft lignin-derived bio-oil was upgraded with LiCoO2 or Co3O4-impregnated hierarchical nano-ZSM-5 catalysts. The synthesized catalysts were characterized by N2-Ads-Des, XRD, XPS, NH3-TPD, FTIR, FESEM and ICP-OES analyses. Upon incorporation of LiCoO2 and Co3O4 onto the HZSM-5 support, the MFI structure of HZSM-5 remained intact. All the catalysts displayed a combination of Type-I and -IV isotherms. The upgraded bio-oil showed a significant increase in the amounts of alkylated guaiacols owing to the reduction in unsubstituted guaiacols, alkenyl guaiacols, and homovanillic acid. Hydrogenation, alkylation, and deoxygenation were the plausible bio-oil upgrading pathways. With the increase in cobalt content, weak acidity decreased through all the catalysts, while LiCoO2 provided supplementary acid sites that increased the total acidity of LiCoO2/HZSM-5 compared to the Co3O4/HZSM-5 catalyst. LiCoO2/HZSM-5 with a low cobalt content (5% and 10% Co) displayed high selectivity for the production of alkylated guaiacols owing to their strong acidity. The upgraded bio-oils showed an increase in carbon and hydrogen followed by a decrease in oxygen content. The maximum higher heating value (∼29.83 MJ kg-1) was obtained for the 10% Co (LiCoO2)/HZSM-5 catalyst. In general, LiCoO2/HZSM-5 outperformed the Co3O4/HZSM-5 catalyst. XRD of the spent 10% Co (LiCoO2)/HZSM-5 suggested the complete loss of lithium from the catalyst with the retention of the MFI structure of the HZSM-5 support. In this study, it was successfully demonstrated that the main constituent of the cathode material of spent lithium-ion batteries i.e. LiCoO2 could be employed to synthesize a novel and cheap catalyst for bio-oil upgrading while addressing the e-waste management issue in a sustainable manner.

Synergistic Roles of the CoO/Co Heterostructure and Pt Single Atoms for High-Efficiency Electrocatalytic Hydrogenation of Lignin-Derived Bio-Oils.

Electrochemical hydrogeneration (ECH) of biomass-derived platform molecules, which avoids the disadvantages in utilizing fossil fuel and gaseous hydrogen, is a promising route toward value-added chemicals production. Herein, we reported a CoO/Co heterostructure-supported Pt single atoms electrocatalyst (Pt1-CoO/Co) that exhibited an outstanding performance with a high conversion (>99%), a high Faradaic efficiency (87.6%), and robust stability (24 recyclability) at -20 mA/cm2 for electrochemical phenol hydrogenation to high-valued KA oil (a mixture of cyclohexanol and cyclohexanone). Experimental results and the density functional theory calculations demonstrated that Pt1-CoO/Co presented strong adsorption of phenol and hydrogen on the catalyst surface simultaneously, which was conducive to the transfer of the adsorbed hydrogen generated on the single atom Pt sites to activated phenol, and then, ECH of phenol with high performance was achieved instead of the direct hydrogen evolution reaction. This work described that the multicomponent synergistic single atom catalysts could effectively accelerate the ECH of phenol, which could help the achievement of large-scale biomass upgrading.

Catalytic upgrading of lignin-derived bio-oils over ion-exchanged H-ZSM-5 and H-beta zeolites

H-ZSM-5 and H-Beta zeolites ion-exchanged with alkali (Na+ and K+) and alkaline-earth (Mg2+) metals have been explored for the catalytic fast pyrolysis of lignin. Incorporating these metals led to a significant change in the acidic properties of the parent zeolites turning into mostly Lewis-type acidity. Catalytic fast pyrolysis experiments of lignin were performed in a fixed bed reactor with ex-situ configuration operating at 550 °C (thermal zone) and 450 °C (catalytic zone), atmospheric pressure and under a nitrogen flow. Moreover, two catalysts to lignin mass ratios (C/L = 0.2 and 0.4) were studied. Compared with non-catalytic tests, the use of parent zeolites caused a decrease in the bio-oil* (water-free basis) yield due to enhanced production of gases, water, and the coke deposition on the catalyst. In addition, the quality of bio-oil* was improved since it presents a lower oxygen content regarding the thermal test. H-Beta zeolite showed a higher deoxygenation degree than H-ZSM-5, but the latter exhibited a higher share of light components in the bio-oil* that can be detected by GC-MS analyses. Both catalysts promoted the production of light oxygenates, aromatics, and oxygenated aromatics. Regarding the effect of the incorporation of metals, oxygenated aromatic compounds were the predominant family in the bio-oil* obtained with all ion-exchanged zeolites. Likewise, significant differences were observed among the catalysts regarding the main components of this family (alkylphenols, guaiacols, syringols, catechols, and methoxybenzenes), achieving guaiacols concentrations in bio-oil* near to 24 wt.% for NaH-ZSM-5 and KH-ZSM-5 catalysts, and alkylphenols concentrations close to 16 wt.% for MgH-Beta and KH-Beta zeolites.

Lignin meets MOFs: Lignin derived metal carbon material for the catalytic hydrotreatment of guaiacol to cyclohexanol

Catalytic upgrading lignin-derived bio-oil with high oxygen content to directly usable transport fuel through hydrotreatment is highly desirable, but still remains a challenge. In this work, a series of Co-based catalysts were synthetized using metal–organic frameworks (MOFs) as a structure-directing agent and lignin as a renewable carbon precursor via a simple hydrothermal method. Among these catalysts, Co/C-EL-0.5–500 showed the best catalytic hydrotreatment activity, affording 100% guaiacol conversion with 90% cyclohexanol yield under the conditions of 240 °C, 0 MPa N2 and 4 h. According to the characterization results of XRD, SEM, TEM, BET, ICP, NH3-TPD and XPS, the excellent performance of Co/C-EL-0.5–500 was attributed to large specific surface area, small Co particle size, and optimal acidity. The possible reaction pathway was proposed based on the product distribution. In addition, isopropanol was used as H-donor instead of extra hydrogen, and we hope that it could provide a novel strategy for bio-oil upgrading.

Single-atom Au atomically trapped in WO3−x catalyst for selective demethoxylation of lignin-derived guaiacols

Utilizing the reducibility of oxygen vacancies and the low hydrogenation of single metal atoms, Au atoms automatically trapped in WO3−x. The resultant catalyst was characterized by many technologies to analyze its structure and morphology and exhibited high activity in the demethoxylation of 4-propylguaiacol, which was attributed to the synergistic effect between single Au atom and oxygen vacancy. The presence of Au enhanced the hydrogen dissociation but its single atom had a low hydrogenation activity, resulting in the total monophenols selectivity and yield of 98.3% and 94.2% at 225 °C, respectively. This Au/WO3−x catalyst also exhibited high stability: both the demethoxylation activity and structure were almost unchanged after 5 cycle runs. This preparation method was suit to fabricate other analogous catalysts such as Pt/WO3−x-R, Pd/WO3−x-R, Ir/WO3−x-R and Ru/WO3−x-R with high demethoxylation activity. In addition, other lignin-derived guaiacols were also successfully converted into the corresponded monophenols on Au/WO3−x catalyst. This study applied single atom catalyst into the demethoxylation of guaiacols, which provided a universal method to fabricate single metal atom trapped in WO3−x catalysts towards upgrading lignin-derived bio-oil into value-added chemicals.

Rational design of Ni-MoO3–x catalyst towards efficient hydrodeoxygenation of lignin-derived bio-oil into naphthenes

Design of a robust catalyst with high activity but the low cost for the hydrodeoxygenation (HDO) of bio-oils is of great importance to bring the biorefinery concept into reality. In this study, density functional theory (DFT) calculation was adopted to analyze the optimal location of Ni on MoO3–x containing oxygen vacancy, and the corresponding result demonstrated that metallic Ni cluster located at the neighborhood of oxygen vacancies would significantly evoke HDO activity. Enlightened by DFT results, NiMoO4 was first hydrothermally synthesized and then employed to fabricate Ni-MoO3–x catalyst via a low-temperature reduction, where Ni escaped from NiMoO4 and was reduced to its metallic state. Such an evolution of Ni species also induced the formation of oxygen vacancies around metallic Ni cluster. In the HDO of p-cresol, Ni-MoO3–x exhibited high activity with a complete conversion and a methylcyclohexane selectivity of 99.4% at 150 °C. Moreover, the catalyst showed good versatility in catalyzing HDO of diverse lignin-derived oxygenates and lignin oil. 2D HSQC NMR, gas chromatograph and elemental analysis of the lignin oil demonstrated the high deoxygenation efficiency and saturation of the benzene ring over Ni-MoO3–x. In the upgrading of crude lignin oil, the deoxygenation degree was up to 99%, and the overall carbon yield of the naphthenes was as high as 69.4%. Importantly, the structures and carbon numbers of the naphthene products are similar to jet fuel-range cycloalkanes, which are expected to have a high density that can be blended into jet fuel to raise the range (or payload) of airplanes. This work demonstrates the feasibility for improving the targeted catalytic reactivity by rational tailoring the catalyst structure under the guidance of theoretical analysis, and provides an energy-efficient route for the upgrading of lignin crude oil into valuable naphthenes.

Earth-abundant Co nanoparticles encapsulated in N-doped hollow carbon sphere for highly selective hydrodeoxygenation of biomass-derived vanillin

Catalytic hydrodeoxygenation (HDO) of lignin-derived bio-oils to value-added biofuels is of great importance to efficient utilization of renewable biomass. Precisely tailoring the surface microenvironment of supported metal nanocatalysts plays a significant role in regulating the interaction between reactants and catalytic active sites and facilitates the acquiring of high-performance HDO catalysts for lignin upgrading. Herein, we report a step-economic synthesis of N-doped hollow carbon sphere encapsulated with Co nanoreactors (Co@NHCS-X, X: 700-1000) via the template-directed in-situ crystallization of Co-based ZIF-67 (zeolite imidazolate framework) and pyrolysis process. The optimized Co@NHCS-900 nanocatalyst presented a 100% conversion and 96% selectivity towards valuable 2-methoxy-4-methylphenol (MMP) biofuel through HDO of bio-oils-based vanillin. Such excellent catalytic performance was attributed to the specific structure properties and surface microenvironment of Co@NHCS nanocatalysts. It was demonstrated that the electronic interaction between embedded Co nanoparticles and surface nitrogen species of NHCS nanoreactors constructed desired microenvironment and generated abundant surface Co active species, which could effectively enhance activation capabilities of reactants and intermediate, and achieve highly selective HDO of vanillin to MMP via promoted adsorptions of CO/CO bonds as confirmed by intrinsic kinetic evaluations and density functional theory (DFT) calculations. Moreover, a two-step of hydrogenation/hydrogenolysis tandem reaction pathway of vanillin HDO to MMP and the corresponding catalytic reaction mechanism were proposed. Besides, the hierarchical porous structure of NHCS facilitated the dispersion and stabilization of encapsulated Co nanoparticles and endowed Co@NHCS-900 nanocatalyst with good stability in recycling tests. This work provided new insights into rational design of efficient and stable metal nanocatalysts for biomass conversion.

Hydrodeoxygenation of lignin derived bio-oil into aromatic hydrocarbons over Ni-Cu-Ru/HZSM-5 catalyst

The complexity and diversity of lignin derived bio-oil (LDB) has posed a great challenge to the subsequent processing and utilization. In this work, HZSM-5 was modified by sodium hydroxide and followed by Ni, Cu and Ru species. LDB was used as the raw biocrude to prepare bio-oil rich in aromatic hydrocarbons with modified HZSM-5 catalysts under supercritical ethanol conditions (320 °C, 14 MPa). Results showed that the desilicated HZSM-5 with the loading of Ni, Cu and Ru (Ni-Cu-Ru/DeHZSM-5) exhibited the best catalytic performance with a high relative amount of aromatic hydrocarbons of 28.95%. After catalytic hydrodeoxygenation (HDO) of LDB, 80.40% upgraded bio-oil (UBO) with 96.32% energy recovery was obtained in the presence of Ni-Cu-Ru/DeHZSM-5. Demethoxylation and dehydration were the main reactions in the catalytic HDO process. Potential reaction pathways of guaiacol, syringol and creosol were also proposed in this paper. The heating value of UBO reached 35.22 MJ/kg compared with LDB, which was increased by 19.80%. The water content and viscosity of UBO were also significantly improved. The micro-mesoporous structure of modified HZSM-5 with loading of Ni, Cu and Ru was beneficial to promote the yield of the aromatic hydrocarbons.

Novel Diesel-Like Liquid Fuel Production by Hydrodeoxygenation–In Situ Esterification of Lignin-Derived Bio-oil and Plant/Animal Oil

Biofuels can be produced from lignin and plant/animal oil by thermochemical conversion. On the basis of traditional methods, a novel strategy was proposed for the first time to produce diesel-like liquid fuel from lignin-derived bio-oil and plant/animal oil by hydrodeoxygenation–in situ esterification, which can fully utilize both aromatic units and −OCH3 groups of lignin. Guaiacol and lauric acid were selected as model compounds of two feedstocks, respectively. Cyclohexyl laurate and methyl laurate with cetane values of 59.2 and 63.9, respectively, were obtained, of which the fuel properties satisfied the biodiesel standard. The yield of esters reached 112.5 mol % with nearly complete conversion of guaiacol. In contrast, the presence of the additional −OCH3 group linked to the sixth carbon of 2,6-dimethoxylphenol hindered the formation of cyclohexanol while increasing the yield of methanol. In addition, lignin-derived dimers could also be efficiently converted into the diesel-like liquid fuel rich in esters and cycloalkanes.

Hydrodeoxygenation of lignin-derived phenolics to cycloalkanes over Ni–Co alloy coupled with oxophilic NbOx

Hydrodeoxygenation (HDO) of lignin-derived bio-oil is a promising route to produce advanced biofuels. However, the removal of oxygen-containing functional groups with high bond strength in bio-oil challenges the development of efficient, stable, and inexpensive catalysts. In this study, a series of bifunctional catalysts were synthesized by coupling Ni–Co alloy with an oxophilic NbOx support, which was used for the HDO of lignin-derived phenolics to produce cycloalkanes. The Ni–Co alloy formed on the bimetallic catalysts during calcination and reduction was verified by TEM, XPS, and H2-TPR measurements, which showed excellent hydrogenolysis activity. The composition of the Ni–Co alloy was the most uniform with a Ni/Co molar ratio of 1, and the catalyst achieved the highest catalytic activity. The oxygen vacancies provided by the NbOx support also enhanced the adsorption of phenolics and promoted the removal of oxygen-containing functional groups by forming a specific configuration. The synergistic catalysis of Ni–Co alloy and oxygen vacancies achieved complete conversion of guaiacol with a high cycloalkane selectivity of 98.9 % under optimal conditions (300 °C, 3 MPa H2, and 2 h). More importantly, only marginal deactivation occurred on the 5Ni–5Co/NbOx catalyst after 5 cycles and it was also successfully applied to the efficient conversion of other complex lignin-derived phenolics. Therefore, an efficient and economical strategy of coupling the Ni–Co alloy with an oxophilic NbOx support to catalyze the HDO of lignin-derived phenolics to produce cycloalkanes was prospective.

Catalytic hydrodeoxygenation of phenolic compounds over Ru-MoFeP/Al2O3 catalyst

Catalytic converting the lignin-derived bio-oil to liquid fuel is one promising methodology to reduce the dependence on petroleum-based fuel while easing the atmospheric carbon dioxide burden. Hydrodeoxygenation (HDO) is one commonly used method to convert and upgrade bio-oil from biomass. In the present work, a Ru-promoted MoFeP/Al2O3 catalyst was prepared and evaluated the HDO performance by converting two model compounds, guaiacol and anisole with a batch reactor at 250 °C. This catalyst shows a quite good HDO performance over the two model compounds, in which, oxygen was removed from the phenolic and hydrocarbons were produced as the product. Kinetic studies were also performed to build the reaction network and elucidate the reaction pathway of guaiacol and anisole HDO reactions. The primary, secondary, and tertiary products can be identified for the HDO reactions. A better understanding of HDO chemistry from the fundamental study can lead to more efficient catalysts for the target products.

Value added hydrocarbons from lignin derived bio-oils: Insights from process simulations

Lignin is the natural source of aromatics on our planet. Depolymerization of lignin generally produces oxygenated monomers (aromatics compound) such as phenol, guaiacol, and syringol over zeolite catalyst, known as lignin-derived bio-oil. These are valuable building blocks for producing important chemicals and fuel range hydrocarbons such as benzene and toluene. Hydrodeoxygenation (HDO) is a promising route for converting lignin-derived bio-oil into benzene and toluene. In this study, Aspen HYSYS is used as process simulator to simulate the HDO process for converting lignin-derived bio-oil (i.e., guaiacol) to benzene and toluene. Process simulation results are then used to extract optimal reaction conditions for benzene and toluene production from guaiacol. Based on the results obtained, it is found that production of benzene is favored at low pressure and low temperature whereas toluene formation is favored at high pressure and high temperature. These observations are found to be in line with the reaction mechanisms for the conversion of guaiacol to benzene and toluene via HDO route.

Efficient hydrodeoxygenation of lignin-derived bio-oil to hydrocarbon fuels over bifunctional RuCoWx/NC catalysts

Efficient hydrodeoxygenation of lignin-derived bio-oils to cycloalkanes was achieved over bifunctional RuCoWx/NC catalyst prepared by in situ pyrolysis method. The performance of RuCoWx/NC was investigated in HDO of 4-propylguaiacol, considering the influences of catalysts, initial H2 pressure, and reaction temperature. Catalyst screening reveals that RuCoW0.03/NC afforded the highest propylcyclohexane yield of 71.3% from 4-propylguaiacol at 220 ℃. At 240 ℃, the yield of propylcyclohexane increased to 95.2 %. The heavy fraction of rice husk bio-oil, primarily composed of lignin-derived phenolic compounds, could be upgraded to 98.3% hydrocarbons at 280 ℃ over RuCoW0.03/NC. The synergistic interaction between highly dispersed Co and Ru metal sites and WOx acidic sites is responsible for the excellent HDO activity of RuCoW0.03/NC. Besides, RuCoW0.03/NC exhibited high stability after four cycles.

Selective Catalytic Transfer Hydrogenation of Lignin to Alkyl Guaiacols Over NiMo/Al-MCM-41.

Efficient deoxygenation of lignin-derived bio-oils is central to their adoption as precursors to sustainable liquid fuels in place of current fossil resources. In-situ catalytic transfer hydrogenation (CTH), using isopropanol and formic acid as solvent and in-situ hydrogen sources, was demonstrated over metal-doped and promoted MCM-41 for the depolymerization of oxygen-rich (35.85 wt%) lignin from Chinese fir sawdust (termed O-lignin). A NiMo/Al-MCM-41 catalyst conferred an optimal lignin-derived oil yield of 61.6 wt% with a comparatively low molecular weight (Mw =542 g mol-1 , Mn =290 g mol-1 ) and H/C ratio of 1.39. High selectivity to alkyl guaiacols was attributed to efficient in-situ hydrogen transfer from isopropanol/formic acid donors, and a synergy between surface acid sites in the Al-doped MCM-41 support and reducible Ni/Mo species, which improved the chemical stability and quality of the resulting lignin-derived bio-oils.

Mild hydrodeoxygenation of lignin-derived bio-oils to hydrocarbons over bifunctional ZrP2O7-Ni12P5 catalysts

An imperative current challenge for the production of renewable fuels is the development of efficient catalytic hydrodeoxygenation (HDO) of phenolic-rich bio-oils into hydrocarbons. In this work, a series of bifunctional ZrP2O7(x)-Ni12P5 (where × represents the molar ratio of Zr/Ni in the catalysts) catalysts were prepared for HDO of lignin-derived bio-oils (LBO). The characterization results show that among these bimetallic catalysts, ZrP2O7(0.4)-Ni12P5 possesses the largest specific surface area, pore volume and the highest amount of acid sites (Lewis and Brønsted) due to the introduction of appropriate amount of Zr species. Meanwhile, the interaction between Niδ+ and Zr species on its surface creates new active sites for the promotion on the hydrogen adsorption and activation, thus endowing the most excellent catalytic performance. Using the optimized catalyst of ZrP2O7(0.4)-Ni12P5, 95.8% cyclohexane yield could be obtained from the HDO of guaiacol as a model compound from bio-oil under mild condition (3 MPa H2 and 250 ℃). Moreover, 36.1% hydrocarbon yield is achieved from HDO of lignin-derived bio-oils (LBO) under the same hydrogen pressure and temperature. These findings not only open a novel avenue for designing a cost-effective metal–acid bifunctional catalyst, but also provide a viable approach for converting lignocellulosic biomass feedstocks into valuable hydrocarbons.

Creating Edge Sites within the Basal Plane of a MoS2 Catalyst for Substantially Enhanced Hydrodeoxygenation Activity

A two-dimensional MoS2 catalyst uses edge sites for catalytic activity while its basal plane remains inert in heterogeneous catalysis. To significantly boost the intrinsic activity of MoS2, a metal insertion–deinsertion procedure was developed to prepare Pt–MoS2–x catalysts. Of which, Pt4+ partially substituted Mo4+ in the basal plane of 1T-MoS2–x and then Pt was deinserted from the basal plane after reduction and finally located at the neighborhood of its original position, where abundant edge sites were created and rich Pt–edge interfaces were formed in the “inert” basal plane of MoS2. This Pt–MoS2–x exhibited high activity in hydrodeoxygenation of p-cresol, presenting in 100% oxygen removal at a low temperature of 120 °C and almost no sulfur loss nor deactivation in recycling runs. A Pt–MoS2–x catalyst was also efficient in hydrodeoxygenation of diverse lignin model compounds and lignin-derived bio-oil. This methodology opens up an innovative strategy for the design of robust MoS2 catalysts featuring the activation of the basal plane and provides an energy-efficient alternative for the upgradation of raw bio-oil.

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%.