Mechanism Of Hydrodeoxygenation Research Articles

A first-principles study on the hydrodeoxygenation mechanism of the lignin-derived phenolic compounds over MoS2 catalysts

Understanding the hydrodeoxygenation (HDO) mechanism of phenolic compounds is crucial for advancing catalytic upgrading techniques of bio-oil. Herein, a comprehensive theoretical study of the HDO of lignin-derived phenolic compounds (phenol, cresols, and guaiacol) on the MoS2 surface was carried out using periodic density functional theory (DFT) calculations. Adsorption of phenolic compounds on different crystal faces was first compared. The MoS2 (100) crystal face is more favorable for the adsorption of phenolic compounds which show the horizontal adsorption configurations. Three kinds of HDO patterns were explored for the phenolic compounds. Phenol tends to transform into benzene via stepwise deoxygenation and hydrogenation under the induction of active hydrogen. For cresol isomers, their HDO mechanisms differ from each other due to the influence of the methyl group on the dehydroxylation process. Specifically, o-cresol follows a synergistic process of deoxidation and hydrogenation, m-cresol undergoes a two-step reaction involving direct dehydroxylation and hydrogenation, and p-cresol involves the identical HDO pathway as phenol. With regard to guaiacol, the preferred HDO route involves successive dehydroxylation and demethoxylation to benzene with the anisole intermediate. In addition, the adsorption of phenolics over transition metal-doped MoS2 catalysts was further explored to examine the potential of metal doping for the HDO of phenolics. The doping of Ta and W increases the adsorption capacity, which shows the potential to enhance the HDO activity of the catalyst theoretically.

Study on the catalytic hydrodeoxygenation of lignin dimers: Adsorption properties and linkages cleavage

Production of mono-phenols through hydrodeoxygenation is one of the most promising routes for value-added lignin valorization. However, the adsorption characteristic of key intermediates and hydrodeoxygenation mechanism of key linkages in lignin have received inadequate attentions. In this paper, experiments combined with density functional theory calculations were done to explore the adsorption and catalytic HDO mechanism of lignin dimers. It was found that NiFe(111)-Mo2C(001) had a better ability on linkages activation, and showed stronger adsorption on CO containing intermediates, which was favor for further hydrodeoxygenation. Moreover, the calculation results certificated the cleavage of β-O-4 was prior to the hydrodeoxygenation of CO, and the hydrodeoxygenation of β-O-4 included a H· addition to O atom before the C-O cleavage. Finally, the elementary reactions energy barriers were efficiently reduced by NiFe(111)-Mo2C(001) catalyst during the hydrodeoxygenation reactions, which elucidated the superior performance of NiFe catalyst. This work provides a theoretical basis on efficient lignin utilization.

Understanding the influence of solvents on the Pt-catalyzed hydrodeoxygenation of guaiacol

Bio-oil derived from fast pyrolysis of lignocellulosic biomass needs to be deoxygenated to become a substitute for petroleum fuels. Here, we study the hydrodeoxygenation mechanism of guaiacol, a bio-oil model compound derived from the lignin fraction of biomass, on Pt(111) terrace sites in the presence of water, diethyl ether, 1-butanol, and n-hexane as solvent. Using first-principles periodic density functional theory (DFT) calculations and mean-field microkinetic reactor modeling, a detailed reaction mechanism is investigated targeting various products such as catechol, phenol, anisole, benzene, cyclohexanone, and cyclohexanol. Solvent phase DFT outcomes are mostly similar to that of the vapor phase; however, microkinetic modeling results suggest that rate controlling species and transition states differ somewhat in the various reaction environments. Catechol was found to be the major aromatic product across all reaction environments. Over Pt(111), unsaturated monooxygenate production from catechol is unlikely.

Comparison of hydrocracking and cracking of pyrolytic lignin over different Ni-based catalysts for light aromatics production

This work compared hydrocracking and cracking of pyrolytic lignin (PL) for light (single-ring and double-ring) aromatics production over Ni-based catalysts. Due to the supports' original acidities and the interactions between metal and supports, these Ni-based catalysts had different amounts of available Ni and acid sites, which affected depolymerization and deoxygenation in both cracking and hydrocracking. During cracking, the PL depolymerization could be promoted by increasing Ni and acid sites but this promotion was limited by the hydrogen inside PL, whereas both Ni and acid sites exhibited poor performance in deoxygenation. The cooperation of Ni and acid sites achieved efficient hydrodepolymerization and hydrodeoxygenation in hydrocracking. Acid sites benefitted the cracking of linkages in PL and the resulting intermediates could be converted into monophenols through Ni-catalyzed hydrogenation. In the selective hydrodeoxygenation mechanism of monophenols to monoaromatic hydrocarbons, acid sites facilitated the initial tautomerization and the final dehydration reactions, while the middle hydrogenation step was catalyzed by Ni. Additionally the micropore structure of catalyst also favored the generation of light aromatics. Therefore, hydrocracking over Ni/HZSM-5 with sufficient available Ni and acid sites and the micropore structure, realized the most effective conversion of PL to light aromatics, especially aromatic hydrocarbons.

Creating values from wastes: Producing biofuels from waste cooking oil via a tandem vapor-phase hydrotreating process

This study is focused on producing biofuels from waste oils via a tandem vapor-phase hydrotreating process in a pressurized two-stage fixed bed reactor over a bifunctional Ni/Al2O3-SiO2 catalyst under 0.25 MPa H2. A 100% hydrodeoxygenation efficiency both in liquid and gas products was observed, yielding 83.9 wt% C5-C19 n-alkanes which corresponds to a 7.4-fold increase compared with that obtained from non-catalytic conversion. The hydrodeoxygenation mechanism of waste cooking oil in the catalytic tandem hydrotreating process induced by Ni/Al2O3-SiO2 was proposed. The hydropyrolysis temperature in the first reactor, hydrogenation temperature in the second reactor, reaction pressure, catalyst to waste cooking oil mass ratio, and gas hourly space velocity (GHSV) was optimized at 550 °C, 300 °C, 0.25 MPa, 3, and 56 s−1, respectively. The application potential of this cascade vapor-phase hydrotreating process was evaluated by employing different waste oils such as palm kernel oil, woody oil (swida wilsoniana), soapstock, and waste lubricating oil as feedstock, giving C5 to C19 n-alkane yields ranging from 21.6 to 87.5 wt%. This work provides a novel and promising approach to upcycle waste oils into upgraded biofuels compared with conventional catalytic pyrolysis.

The adsorption behavior of phenol on the surface of 1D/2D M@MoS2 (M = Co and Rh) for hydrodeoxidation reaction: Insights from theoretical investigations

As MoS2 is a useful catalyst for phenol hydrodeoxidation, it is important to develop MoS2 based catalysts. However, identifying active site remains challenging. In the present study, two monatomic catalysts, namely, Vs-Co@MoS2 and Rh@MoS2, were prepared and on which the adsorption sites of phenol were investigated via density functional theory (DFT). By systemically comparing the adsorption configuration, adsorption energy and adsorption distance, we found that the most stable configuration of phenol on 2D Vs-Co@MoS2 monatomic catalyst was from η6 adsorption mode (horizontal adsorption; adsorption energy, −1.51 eV; adsorption distance, 1.7 Å), and the adsorption site was the Co-Vs interface that formed by an isolated Co atom and its adjacent S vacancy (Vs) site. The density of state (DOS) analysis indicated the adsorption active sites originated from defect states and orbital hybridization distribution near Fermi level. As for 1D Rh@MoS2, the adsorption site was coming from the isolated Rh1 atom, whose selectivity towards phenol was strengthened by the steric confinement effect of the unique pocket-like structure (Ho-Mo-Rh1-Mo-OH). It was hoped that this study would provide important ideas for exploring the hydrodeoxygenation mechanism of phenol compounds.

Mechanism of Guaiacol Hydrodeoxygenation on Cu (111): Insights from Density Functional Theory Studies

Understanding the mechanism of the catalytic upgrade of bio-oils via the process of hydrodeoxygenation (HDO) is desirable to produce targeted oxygen-deficient bio-fuels. We have used calculations based on the density functional theory to investigate the reaction mechanism of HDO of guaiacol over Cu (111) surface in the presence of H2, leading to the formation of catechol and anisole. Our analysis of the thermodynamics and kinetics involved in the reaction process shows that catechol is produced via direct demethylation, followed by dehydrogenation of –OH and re-hydrogenation of catecholate in a concerted fashion. The de-methylation step is found to be the rate-limiting step for catechol production with a barrier of 1.97 eV. Formation of anisole will also proceed via the direct dehydroxylation of guaiacol followed by hydrogenation. Here, the rate-limiting step is the dehydroxylation step with an energy barrier of 2.07 eV. Thermodynamically, catechol formation is favored while anisole formation is not favored due to the weaker interaction seen between anisole and the Cu (111) surface, where the binding energies of guaiacol, catechol, and anisole are -1.90 eV, −2.18 eV, and −0.72 eV, respectively. The stepwise barriers also show that the Cu (111) surface favors catechol formation over anisole as the rate-limiting barrier is higher for anisole production. For catechol, the overall reaction is downhill, implying that this reaction path is thermodynamically and kinetically preferred and that anisole, if formed, will more easily transform.

Biphasic Titania Derivatives of Titanium Metal‐Organic Framework Nanoplates for High‐Efficiency Photoreduction of Diluted CO2 to Methane

AbstractExploring earth‐abundant materials for low concentration CO2 photoreduction is the key in the energy related field. Here, we demonstrated biphasic titania (anatase and rutile) derived from Ti‐based metal‐organic framework (MOF) nanoplates exhibited excellent performance in CO2 photoreduction without any co‐catalysts and sacrificial agents under ambient condition, the maximum CH4 production rate was up to 65.39 μmol g−1 h−1 with near 100 % electron selectivity as well as great stability. The activity of the optimal derivative was maintained well even in 1 % CO2 (CH4: 45.59 μmol g−1 h−1) and much better than that of commercial P25. The upgraded performance originated from the synergism between local anatase/rutile interface and numerous defective sites (Ti3+ and Ov), by promoting the separation and migration of photogenerated carriers, CO2 adsorption and activation, and H2O dissociation. Besides, a possible fast hydrodeoxygenation mechanism for methane formation was proposed according to in situ DRIFTS characterization.

Study on hydrodeoxygenation mechanism of anisole over Ni (111) by first-principles calculation

Anisole, as an aromatic oxygenate lignin model compound, which can be selectively cleaved into benzene over Ni/C at high temperature. On the basic of experimental results, the hydrodeoxygenation (HDO) mechanism of anisole was investigated on clean Ni (111) surface by using computational techniques. Based on static energies, the microkinetic modeling on clean Ni (111) and H-covered Ni (111) were built in which the modeling of H-covered Ni (111) approximately simulated the real catalytic system under lower temperature and higher H2 pressure. As a result, the microkinetic analysis proved the phenol was the major product in the anisole decomposition on clean Ni (111) surface. However, the phenol was preferred to decompose rather than desorb from Ni surface because of the high desorption energy, suggesting that the benzene mainly originated from the secondary dissociation of phenol. Differently, the decreasing of energy barrier for anisole hydrogenation led to the formation of methylcyclohexane as main product on H-covered Ni (111) surface by microkinetic analysis. The differences in products distribution between Ni (111) and H-covered Ni (111) provided a mechanistic understanding for anisole conversion under different experimental conditions.

Cu/CuMgAlOx-Catalyzed Guaiacol Hydrodeoxygenation in Supercritical Methanol: A Modeling Mechanistic Insight for Lignin-Derivatives Upgrading

The development of an economic and sustainable catalytic system was crucial for lignin-based biorefinery. Herein, we reported a low-cost Cu/CuMgAlOx catalyst with promising activity toward lignin hydrodeoxygenation (HDO) through a H2-free method. Supercritical methanol was used as the hydrogen donor, solvent, and reactant simultaneously. Guaiacol was employed as a representative lignin model compound to reveal the HDO mechanism of lignin derivatives. HDOs of guaiacol performed at 250, 275, 300, and 350 °C with durations ranging from 15 to 120 min indicated a high HDO efficiency of the catalytic system. The obtained liquid products were categorized to oxygen-containing unsaturated products (OUPs), oxygen-containing saturated products (OSPs), and cycloalkanes. A kinetic model based on a simplified reaction process containing the three following conversion steps was established: guaiacol transformed to OUPs through the initial HDO, then hydrogenated to OSPs (medium HDO), and eventually turned to cycloalkanes by the deep HDO. The deep HDO was the rate-determining step, and the apparent activation energies of the three steps were all lower than those in the literature. Phenol, 1,2-cyclohexanediol, anisole, and veratrole were the major intermediates, the HDOs of which were programed for pathway verification. Remarkably, catechol (the culprit of condensation) was not produced in this system. Overall, a detailed reaction network of guaiacol HDO was established, and the veil of Cu/CuMgAlOx-catalyzed lignin-derivatives HDO in supercritical methanol was revealed. This work paved the way for the application of Cu/CuMgAlOx catalyst in lignin-derivatives upgrading.

Ambient-pressure and low-temperature upgrading of lignin bio-oil to hydrocarbons using a hydrogen buffer catalytic system

Catalytic hydrodeoxygenation is an essential step for bio-oil upgrading. However, hydrodeoxygenation usually requires a high hydrogen pressure and high temperature due to the good stability of the C–O bonds. Here we report an effective multiphase hydrodeoxygenation of lignin-based bio-oil at temperatures <100 °C and hydrogen pressures <1 atm using a synergetic catalyst system that consists of a low redox potential H4SiW12O40 (SiW12) and suspended Pt-on-carbon (Pt/C) particles. We propose that SiW12 plays three critical roles in bio-oil hydrodeoxygenation. First, it quickly oxidizes the H2 gas to form reduced SiW12 in the presence of Pt/C. Second, it transfers both electrons and H+ ions to the bulk phase to form active H* or H2 on the Pt/C surface. Third, the formation of the oxonium ion in a SiW12 superacid solution reduces the deoxygenation energy. The SiW12-enhanced proton-transfer hydrodeoxygenation mechanism is supported by density functional theory computations. As a result of the hydrogen buffer and acidic effect, up to a 90% yield of hydrocarbons (cyclohexane, benzene and their derivatives) was achieved from the hydrodeoxygenation of phenol and its derivatives. Bio-oil derived from biomass has great potential as a more sustainable fuel but its formation typically relies on energy-intensive processes. Liu et al. show how a tri-phase hydrogen-transfer catalytic system can drive hydrodeoxygenation in water under mild conditions to achieve up to 90% hydrocarbon yield.

Study on Catalyst Deactivation During the Hydrodeoxygenation of Model Compounds

To address the pressures associated with an increasing energy demand and rising cost of liquid fuel production, alternative feedstocks are being developed. One such potential replacement is bio-oils, which are derived from biomass, however the oil produced is often chemically unstable, corrosive and has low heating values due to the high oxygen content. Thus, an upgrading process is required to lower the oxygen content, with catalytic hydrodeoxygenation being one such technology currently being developed, with mechanistic studies commonly completed utilising model compounds. The current study examines factors that influence catalyst deactivation during hydrodeoxygenation of common bio-oil model compounds over zeolite-supported nickel catalysts, indicating the contribution of functional groups on the formation of condensed-ring products and catalyst deactivation. It was determined that phenolic-hydroxyl groups present in model compounds can facilitate catalyst deactivation through the formation of condensed-ring compounds, identified through decreased cycloalkane yields, causing blockage of catalyst pores. Conversely, when toluene, cyclohexanol and anisole were used as model compound feeds, there were no notable changes in cycloalkane yields, indicating aromatic, alkyl–OH and aromatic–OCH3 have negligible effect on catalyst deactivation. The effect of catalyst metal loading was also examined, and while increased metal content enhanced cyclohexane yields, so to was the formation of condensed-ring products, suggested to be the result of an increased concentration of surface cyclohexane carbocations. Modifications to reaction conditions was studied, with catalyst activity and stability found to improve with increasing reaction temperatures up to 230 °C. Based on the product distributions observed, a coupling reaction pathway (leading to the formation of condensed-ring products and cycloalkanes) is proposed as the hydrodeoxygenation mechanism.

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.

Bifunctional metallic-acidic mechanisms of hydrodeoxygenation of eugenol as lignin model compound over supported Cu, Ni, Pd, Pt, Rh and Ru catalyst materials

The hydrodeoxygenation (HDO) reaction kinetics of lignin monomer model compound eugenol was systematically investigated over various commercially available catalysts typically used for lignin valorisation by hydrotreatment. The role of noble metals Pt, Pd, Rh, Ru, and non-noble Ni and Cu on C was investigated in the previous studies, while the present work is focused on the support (Al2O3, SiO2, SiO2-Al2O3, TiO2, HZSM-5) effect on the catalyst activity and selectivity, being estimated experimentally (at 225, 275, 325 °C and 5 MPa of initial hydrogen pressure) and in silico. The micro-kineticmodel took into consideration mass transfer resistances through convective films (gas bubbles and catalyst particles), reaction kinetics in bulk liquid, adsorption/desorption and surface reaction kinetics on metallic and acidic active sites, considering the occurrence of all reactions on both types of sites. The contribution of each support was quantitatively evaluated in terms of adsorption, desorption, and reaction rate constants and activation energies. SiO2-Al2O3 and HZSM-5 showed superior contribution to the activity of the methoxyl and hydroxyl group removal from oxygenated aromatics and particularly saturated species. Except for the above-mentioned materials Caromatic–O hydrogenolysis activity was not substantially affected, while the acidity of the support notably promoted Caliphatic–O cleavage. Contribution to overall hydrogenation rate was practically negligible in presence of acidic sites. It has been also noted that the contribution of supports was not very prominent when very active noble metal phases were used (such as Ru), while it came to the fore in the case of almost inactive Cu, being responsible for formation of 4-propylphenol at 325 °C. Based on microkinetic modelling results, Sankey diagrams were formulated for the first time to represent pathway flux and graphically demonstrate the contribution of each catalytic reaction participating in the overall eugenol HDO mechanism over the used catalysts (and corresponding intermediates) within a complex reaction network, as well as the engagement of metallic and acidic sites.

Furfural Hydrodeoxygenation over a Ruthenium-Based Bifunctional Catalyst in the Presence of a Direct Source of H2

This work presents the results obtained for the gas chromatography-mass spectrometry (GC-MS) monitoring of the liquid-phase hydrodeoxygenation (HDO) reaction of furfural (FFR) to 2-methylfuran (MF) over a bifunctional Ru/RuOx/C catalyst in the presence of a direct source of H2. Hydrogenation and hydrogenolysis reactions of FFR and of the intermediate furfuryl alcohol (FA), respectively, were independently studied to provide insights on the HDO mechanism. The mass spectra monitoring of the kinetic isotope effect indicated the HDO reaction occurs through a two-step mechanism comprising of an initial ruthenium-mediated hydrogenation reaction of FFR to FA. In the second step, the FA thus formed experiences a hydrogenolysis reaction via ring activation where the hydrogen atoms are firstly attached to the C3 carbon generating a ring activated structure and removing the OH group. The observation of the peaks at m/z 85 and 84 in the mass spectrum of the MF product confirms this reaction pathway.

Hydrodeoxygenation of guaiacol as a model compound of lignin-derived pyrolysis bio-oil over zirconia-supported Rh catalyst: Process optimization and reaction kinetics

To explore the mechanism for hydrodeoxygenation (HDO) of bio-oil, which contains large compounds that share similar molecular structures of phenyl ring with oxygen-containing functional groups, guaiacol as a typical model compound of lignin-derived bio-oil was hydrotreated at 150–350 °C under 3–7 MPa (H2) using the synthesized zirconia-supported Rh catalyst in a batch reactor. With Rh/ZrO2 catalyst, guaiacol can be completely converted where reaction temperature plays a decisive role and significantly affects the degree of hydrogenation. HDO Process was optimized with insight into effects of different reaction parameters, including H2 pressure, reactant concentration, reaction time and temperature, on the whole process of HDO and formation of undesired oxygen-contained products. The optimum reaction conditions were 5 wt. % guaiacol, 300 °C and 7 MPa in which guaiacol could be completely deoxygenated with 87. 7 mol% oxygen-free product of cyclohexane in 3 h and the desired O/C and H/C ratios of products were obtained. A specific reaction network including three main steps: “guaiacol → 1-methyl-1,2-cyclohexanediol → cyclohexanone and cyclohexanol → completely deoxygenated compounds of cycloalkanes”, was deduced by a comprehensive study on different reaction parameters and a typical key reaction network for HDO of lignin-derived bio-oil is proposed based on model compounds studies. Kinetic model for HDO of guiaacol with the Rh/ZrO2 catalyst was proposed based on the credible pathway and it fits well to a pseudo-first-order kinetic model that the R2 values obtained for the fittings were all above 0.98 at four temperatures. At low temperature of 150 °C, the kinetically relevant step is hydrogenation of the aromatic ring, yielding 90 mol% 1-methyl-1,2-cyclohexanediol, while at high temperature (≥300 °C), the kinetically relevant step is the complete deoxygenation of oxygen-containing functional groups which mainly yields cyclohexane. These results would be helpful to further understand the HDO mechanism of lignin-derived bio-oil, and the excellent performance of Rh/ZrO2 demonstrated its potential application in bio-oil hydrodeoxygenative upgrading process.

Combined In Situ XAFS and FTIR Study of the Hydrodeoxygenation Reaction of 2-Methyltetrahydrofuran on Ni2P/SiO2

This paper deals with a study of the mechanism of hydrodeoxygenation (HDO) at 0.1 MPa and 300–350 °C of 2-methyltetrahydrofuran (2-MTHF) over a Ni2P/SiO2 catalyst. The study was conducted using in situ Fourier transform infrared (FTIR) spectroscopy to monitor the adsorbed species during reaction and in situ X-ray absorption fine structure (XAFS) to probe the oxidation state of the Ni component. The work is relevant to the upgrading of bio-oil derived from the pyrolysis of biomass. It was deduced that the initial interaction of the 2-MTHF was with OH groups on the catalyst surface, followed by adsorption on Ni sites. Ring-opening of the tetrahydrofuran led to the formation of the main products of the reaction, n-pentane by HDO and n-butane + CO by decarbonylation. The CO band appeared with a slight delay in the FTIR spectrum because the reaction to form n-pentane was favored and turned over about four times before one n-butane + CO was formed.

Mechanism of hydrodeoxygenation (HDO) in anisole decomposition over metal loaded Brønsted acid sites: Density Functional Theory (DFT) study

In this work, the mechanism and intrinsic reaction energy barriers of hydro-deoxygenation (HDO) of anisole, as key stage of the catalytic decomposition over metal-loaded acid support catalysts (bi-functional catalysts), were investigated by Density Functional Theory (DFT). Common transition metals were compared in terms of their adsorption energy when adsorbing anisole molecule for the selection of loading metals. The roles of metal and acid sites in the HDO of phenolic compounds (Phs) over bi-functional catalyst were investigated, and a novel HDO mechanism was proposed by combining Fukui index and bond orders of phenol molecule analyses. HDO reactions of Phs over sole acid sites and the bi-functional catalysts were modelled. The modelling results revealed that, for anisole adsorption, Co, Mo, Ni and Cu showed higher adsorption energy than other transition metals. Molecule analysis results showed that HDO over bi-functional catalysts was dominated by the protonation of the hydroxyl group on Phs. Reaction modelling exhibited that active metals had significant effects in lowering energy barriers of the reactions for all the Phs; the metal active sites facilitated the protonation by developing strong interaction with the adsorbed reactant, and they also aid the hydrogen molecule dissociation. Ni and Mo showed the best catalytic effect on the HDO for most Phs. The effect of side chain methyl substitutes on the HDO reactions for various Phs intermediates during anisole decomposition was also investigated by reaction modelling. Modelling results in this study were found in good agreement with experimental data.

Methyl Butanoate Adsorption on MoS2 Surface: A Density Functional Theory Investigation

Methyl butanoate is one of the compound which is obtained from triglyceride molecule. It has hydrocarbon components and hence may produce hydrocarbon through hydrodeoxygenation (HDO) or decarbonylation (DCO) processes. The first step to uncover the underlying mechanism of HDO or DCO is to find the active site of methyl butanoate adsorption over the catalyst. This study attempts to investigate the active site of methyl butanoate adsorption on MoS2 surface. Stable bonding configuration for methyl butanoate adsorption on MoS2 is investigated by using density functional theory (DFT). This investigation consists of geometry optimisation and adsorption energy calculations. The stable configuration of methyl butanoate adsorption on MoS2 surface is found to be on top of Mo atom in Mo-edge surface.

Hydrodeoxygenation of bio-oil model compounds over amorphous NiB/SiO2-Al2O3 catalyst in oil-water biphasic system

An amorphous NiB/SiO2-Al2O3 catalyst was prepared and characterized by XRD, TEM, N2 sorption and XPS. The hydrodeoxygenation catalytic performance of the prepared catalysts was evaluated in an oil-water biphasic system using anisole and guaiacol as model compounds of bio-oil. The results showed that Ni was in the electron-rich state with the modification of B, leading to the much higher hydrodeoxygenation activity of amorphous NiB/SiO2-Al2O3 catalyst than that of Ni/SiO2-Al2O3 catalyst. Increasing reaction temperature or prolonging reaction time was beneficial to the conversion of guaiacol and anisole. On the basis of the experimental results, the hydrodeoxygenation reaction pathways of guaiacol and anisole were analyzed, which provided a reference for the hydrodeoxygenation mechanism of bio oil.