Hydrodeoxygenation Research Articles

Experimental and simulation investigation on acetone deoxygenation with Ce/Fe-based oxygen carrier

Bio-oil is a renewable energy and a promising alternative to oil, but its disadvantages such as high oxygen content, low higher heating value (HHV), and instability are needed upgrading. For ketones account for a relatively large proportion of bio-oil, acetone is chosen as a single model compound for hydrodeoxygenation (HDO) in this work. The acetone HDO investigation was carried out in a high pressure reactor, using the reduced Fe-based oxygen carrier1 (OC1) and Ce-doping reduced Fe/Al oxygen carrier2 (OC2). The OCs’ evolution was analyzed by XRD, and the liquid phase products were tested by GC–MS. The results showed the OCs played the dual role of carrying oxygen and catalysis and the HDO capability of OC2 on acetone was better than that of OC1. In addition, two molecular structure models of OC1* (reduced iron-based oxygen carrier) and OC2* (Ce-modified Fe/Al reduced oxygen carrier) were established, and the acetone adsorption on OCs* and the H2O dissociation process were simulated with density functional theory (DFT). The analysis showed that the oxygen vacancies generated by Ce-doping and the Al2O3 carrier changed the optimal adsorption sites of acetone and H2O, then promoted the acetone adsorption and H2O dissociation reaction, improved the OCs performance, verifying that OC2 had better HDO performance on acetone. This work provides guidance for the improvement of crude bio-oil upgrading.

Synthesis of renewable diesel and jet fuels from bio-based furanics via hydroxyalkylation/alkylation (HAA) over SO42-/TiO2 and hydrodeoxygenation (HDO) reactions

Upgrading biomass to renewable diesel and jet fuels is essential to achieve carbon neutrality. Herein, diesel and jet fuels range alkanes were produced by HAA of 2-methylfuran and furfural over solid acid SO42-/TiO2 and subsequent HDO over Pd/NbOPO4. A series of SO42-/TiO2 catalysts were synthesized by wetness impregnation to produce C15 fuel precursors. S/Ti-450 with a calcination temperature of 450 °C exhibited the highest activity, affording 97.9 % yield of C15 fuel precursor. Sufficient Brønsted acid sites and moderate Brønsted acid strength are responsible for the super catalytic performance of S/Ti-450. Stability studies demonstrated that S/Ti-450 could be regenerated. Furthermore, the application of S/Ti-450 in the HAA reaction was extended to other carbonyl compounds (e.g., butanal, cyclohexanone and acetone) and high yields of desired fuel precursors were obtained. Finally, C15 fuel precursor was further converted to long-chain alkanes via HDO over Pd/NbOPO4, yielding 85.0 % diesel and jet fuels range alkanes.

A significant support effect on RuSn catalysts for carboxylic acid transformation to hydrocarbons

The ever-increasing demand for substitute energy sources encourages the usage of biofuels as transportation fuel; however, the unstable properties and low calorific value of biofuels caused by high oxygen content limits their direct application. In this study, we report the upgrading of a model biofuel in octanoic acid by hydrodeoxygenation (HDO) using RuSn supported on SiO2-doped Al2O3 (SiAl). The presence of SiO2 on Al2O3 was crucial for the formation of Ru3Sn7 alloy phase because SiO2 modified the metal-support interaction between RuSn and Al2O3. The alloy phase conferred significant hydrogenation activity to convert octanoic acid to octanol and minimized carbon loss by reducing decarbonylation activity. The deposition of SiO2 also resulted in improved acidity, which increased with increasing SiO2 loading from 10 to 30 %, due to the formation of isolated terminal silanols (Si-OH). The presence of the silanol groups was important for dehydration of octanol to octane, since the silanols retained octenes longer on the support, facilitating over-hydrogenation. The cooperative metal-support activity on RuSn/SiAl enables high and selective hydrogenation and dehydration activity for upgrading fatty acids in biofuel to hydrocarbons.

Efficient Hydrodeoxygenation of Lignin-Derived Phenols to C6+ Cycloalkanols/Cycloalkanes over Magnetic Carbon-Encapsulated Nickel Nanospheres

To obtain value-added fuels and chemicals from lignin, it is necessary to explore an efficient catalytic system for hydrodeoxygenation (HDO). In this study, a highly efficient and magnetically separable Ni@C catalyst was synthesized for conversion of lignin-derived phenols. Detailed results showed that the pyrolysis temperature played a crucial role in the difference of the carbon-defect degree, which increased the metal dispersion and the strong electronic metal–support interactions. Meanwhile, we revealed that the differentiated pyrolysis temperature induced the appropriate presence of Ni2+ as Lewis acid sites and Niδ+ as heterohydrogen cleavage sites, which provided an acceleration effect for the HDO reaction. The results displayed that higher reactivity of lignin-derived phenols into C6+ cycloalkanols was achieved over the Ni@C catalyst (100% conversion and 87.19% selectivity). Moreover, the high selectivity of C6+ cycloalkanes was achieved after adding H-ZSM-5 as Brønsted acid sites (100% conversion and 100% selectivity). This investigated work offers an efficient strategy for conversion of lignin-derived aromatics into value-added chemicals.

Impact of Hydrogen Coverage Trend on Methyl Formate Adsorption on MoS2 Surface: A First Principles Study.

Adsorbates coverage plays a crucial role in a catalysis reaction. In hydrodeoxygenation (HDO), which involves high hydrogen pressure, hydrogen coverage on the surface may affect the adsorption of other adsorbates. The HDO is used in green diesel technology to produce clean and renewable energy from organic compounds. This motivates us to study the hydrogen coverage effect on methyl formate adsorption on MoS2 as a model case of the actual HDO. We calculate the methyl formate adsorption energy as a function of hydrogen coverage using density functional theory (DFT) and then comprehensively analyze the physical origin of the results. We find that methyl formate can have several adsorption modes on the surface. The increased hydrogen coverage can stabilize or destabilize these adsorption modes. However, finally, it leads to convergence at high hydrogen coverage. We extrapolated the trend further and concluded that some adsorption modes might not exist at high hydrogen coverage, while others remain.

Defective N, S Co-doped carbon sphere supported Pd catalyst for selective hydrodeoxygenation of biomass under mild conditions

The development and design of high-performance catalysts for biomass hydrodeoxygenation (HDO) under mild reaction conditions is a treacherous challenge. A novel catalyst with low-load Pd supported on N, S co-doped carbon sphere (Pd/CNS) was synthesized for selective HDO of vanillin under mild conditions. The ratio of S, N doping is controllable by adjusting the amount of trithiocyanuric acid and 3-aminophenol precursors added (Pd/CNS-X, X = 0, 0.5, 1, 1.5). According to spectroscopic analysis, N/S doping leads to an increase in the intensity of Pd0/Pd2+, suggesting a remarkable correlation between the electronic structure of the Pd species and carbon support. The Pd/CNS (1) catalysts with S/N = 1 exhibit excellent catalyst activity with a > 99.6 % yield to 2-methoxy-4-methylphenol (MMP) at 50 ℃, superior to without sulfur doping catalyst under mild conditions. Further studies have shown that the coordinated effect of N/S contributes to the formation of electron-rich defect surfaces, which facilitates the stabilization of Pd nanoparticles, promotes the transfer of electrons from the surface to the Pd species and accelerates substrate adsorption. The optimal Pd/CNS(1) catalyst showed stable catalytic performance after being reused five times. The engineering of heteroatom doping on carbon materials offers a novel idea for the design of excellent catalysts to catalyze the conversion of various lignin derivatives.

Simultaneous Pd Nanoparticle Deposition and Enhancement in the Surface Oxygen Vacancy of Bi2MoO6 Nanoflakes for Room Temperature Vanillin Hydrodeoxygenation

A promising method for transforming lignin derivatives into high-value chemicals and biofuels is hydrodeoxygenation (HDO), which is anticipated to be a viable and feasible protocol for the biorefinery. Nonetheless, the requirements of high temperature and high H2 pressure are two main hurdles in the HDO process. Herein, we developed highly active Pd-decorated Bi2MoO6 nanoflakes for complete and selective vanillin (a typical lignin-derived platform molecule) conversion at room temperature and mild H2 pressure. The acquired results reveal that the selection of solvents in vanillin HDO has a detrimental effect, specifically on the product selectivity. When the reaction was performed in dichloromethane solvent, 2-methoxy-4-methylphenol (MMP) was obtained after a 4 h reaction with >99% vanillin conversion and >99% MMP selectivity. Conversely, if water is the reaction medium, it suppresses the formation of MMP, resulting in the selective formation of vanillin’s hydrogenation product vanillyl alcohol (VOL) with 88% vanillin conversion and 91% VOL selectivity. X-ray photoelectron spectroscopy (XPS), Raman, Fourier transform infrared (FT-IR), and ultraviolet (UV)–visible adsorption experimental studies revealed that the superior catalytic performance of the presented catalyst was due to the efficient adsorption of the reactant preferentially through the aldehyde moiety over the catalyst surface and enhancement in surface oxygen vacancies (SOVs) of bismuth molybdate nanoflakes as a result of the treatment with NaBH4 used for Pd nanoparticle deposition. No significant loss in the catalytic activity after multiple cycles proves the stability and good recyclability of the proposed catalyst. This study improves the catalysis strategy of HDO of lignin derivatives and paves the path toward the development of advanced and highly efficient metal-based catalysts for valuable fuels and chemical production from biomass under mild conditions.

Reductive catalytic cracking of industrial phenolics mixture to selective cyclohexanols

Cyclohexanol and its alkyl derivatives are among the most demanding and valuable chemicals. Currently, cyclohexanols are commercially obtained by oxidation of cyclohexanes, derived from fossil-derived benzene and its derivatives. Herein, cyclohexanols are produced from industrial phenolics (IPs) by hydrodeoxygenation (HDO). HDO of IPs was performed over a series of hydrous ruthenium oxide impregnated HY zeolite (HROY) catalysts with varying Ru content. Highest acidity of 10 HROY promoted deoxygenation reactions and strongly interacted small HRO particles with support led to high hydrogenation ability. The effect of solvent mixture (isopropyl alcohol (IPA): water) demonstrated the positive role of water in improving the conversion and selectivity. IPA facilitated the dissolution of IPs while water promoted the adsorption of solubilized molecules on the HRO active sites to lead the proton transfer activity. Maximum conversion (≥99%) was achieved with 87.4% cyclohexanols selectivity (2-methyl cyclohexanol:80.4%, 4-methyl cyclohexanol:5.6% and Cyclohexanol: 1.4%) under optimum reaction conditions.

Multicomponent graphene based catalysts for guaiacol upgrading in hydrothermal conditions: Exploring "H2-free" alternatives for bio-compounds hydrodeoxygenation

Catalytic hydrodeoxygenation (HDO) is a critical technique for upgrading biomass derivatives to deoxygenated fuels or other high-value compounds. Phenol, guaiacol, anisole, p-cresol, m-cresol and vanillin are all monomeric phenolics produced from lignin. Guaiacol is often utilised as a model lignin compound to deduce mechanistic information about the bio-oil upgrading process. Typically, a source of H2 is supplied as reactant for the HDO reaction. However, the H2 supply, due to the high cost of production and additional safety precautions needed for storage and transportation, imposes significant economic infeasibilities on the HDO process's scaling up. We investigated a novel H2-free hydrodeoxygenation (HDO) reaction of guaiacol at low temperatures and pressures, using water as both a reaction medium and hydrogen source. A variety of Ni catalysts supported on zirconia/graphene/with/without nitrogen doping were synthesised and evaluated at 250 °C and 300 °C in a batch reactor, with the goal of performing a multi-step tandem reaction including water splitting followed by HDO. The catalysts were characterised using H2-TPR, XRD, TEM and XPS to better understand the physicochemical properties and their correlation with catalytic performance of the samples in the HDO process. Indeed, our NiZr2O/Gr-n present the best activity/selectivity balance and it is deemed as a promising catalyst to conduct the H2-free HDO reaction. The catalyst reached commendable conversion levels and selectivity to mono-oxygenated compounds considering the very challenging reaction conditions. This innovative HDO approach provides a new avenue for cost-effective biomass upgrading.

Competitive Hydrodeoxygenation and Hydrodenitrogenation Reactions in the Hydrotreatment of Fatty Acid and Amine Mixtures

Understanding how hydrotreating oxygen-containing compounds together with nitrogen-containing compounds affects the reactivity and selectivity is relevant for processing renewable feedstocks. In this work, competitive hydrodeoxygenation (HDO) and hydrodenitrogenation (HDN) reactions were studied by co-hydrotreating palmitic acid (C16 acid) and tetradecylamine (C14 amine) over a Pt/ZrO2 catalyst in a batch reactor. HDO proceeded faster than HDN in the studied system, and the deoxygenation reactions were found to have an inhibitory effect on HDN. Co-hydrotreating the C16 acid and the C14 amine expanded the reaction network from the individual HDO and HDN networks and changed the prevailing reaction pathways, initially in favor of oxygen removal. The formation of heavy secondary amides and amines through condensation reactions became increasingly favored as the share of C16 acid in the feed increased. For a given conversion level, the condensation product selectivity was observed to increase as the reaction temperature was decreased, whereas increasing the reaction temperature promoted the formation of the desired paraffins. This work described the ease of HDO compared to HDN, the role of condensation reactions in the co-hydrotreating reaction network, and the inhibitory effect on HDN thereof.

GuaiacolHDOon La‐modified Pt/Al2O3: Influence of rare‐earth loading

AbstractThe stability of the catalyst used in hydrodeoxygenation (HDO) of biomass‐derived oils needs improvement. La has been applied in delaying Al2O3phase‐change under reaction conditions. Lanthanum (0.5–8 wt.%)‐γ‐alumina was studied as Pt (1 wt.%) carrier aimed at guaiacol (GUA) HDO. Materials characterization included N2physisorption, X‐ray diffraction (XRD), thermal analysis, FTIR, UV–vis, and TPR. Solids pore size (~8–10 nm) was suitable for GUA (kinetic diameter~0.668 nm) hydrotreating. Mixed carriers were amorphous (XRD), suggesting well‐dispersed La domains; meanwhile, carbonates/bicarbonates were formed (from CO2) due to the basic surface properties of modified supports (FTIR). That could impart catalyst stability by inhibiting coking through the passivation of Lewis acidity on Al2O3. Pt reducibility increased with La loading in various formulations. However, that was not reflected in enhanced GUA HDO (T = 488 K and P = 3.2 MPa, batch reactor), presumably due to the strong metal–support interaction (SMSI), where LaOxcovered the metallic Pt particle surface. GUA HDO on various catalysts was approximated by pseudo‐first‐order kinetics (integral regime,k), where deviations were observed as La loading increased, presumably by an SMSI state that could affect the rate‐determining step of the reaction mechanism. Basic sites provided by rare‐earth could contribute to altering HDO reaction pathways as well. At 1 wt.% rare‐earth, GUA HDO was maximized (k~25% higher than that on Pt/Al2O3), with that material also exhibiting similar deoxygenation (85%–90% at total GUA conversion) to the latter Pt over pristine alumina. Conversely, both parameters significantly diminished over the catalyst of the highest La content. Materials at low rare‐earth concentrations deserve further studies focused on catalyst stability under HDO conditions.

Efficient Cu-based catalysts for the selective demethoxylation of guaiacols

Lignin is an attractive feedstock for low molecular weight biobased phenols using depolymerization strategies such as reductive catalytic fractionation or fast pyrolysis. Such strategies often yield a product mixture enriched in lignin-derived monomers with methoxy substituents. Selective catalytic hydrodeoxygenation (HDO) is an effective methodology to demethoxylate these monomers into valuable alkylated phenols. Here, we report the use of non-precious Cu based catalysts supported on SiO2, ZrO2, TiO2 (various forms), MoO3-ZrO2, and MoO3-TiO2 in a continuous fixed-bed reactor at elevated temperature and pressure (300–360 °C, 10 bar) for the selective demethoxylation of guaiacol. Among the various catalysts, Cu/TiO2-P25 was found to be an effective and highly stable catalyst (100 h on stream) with a selectivity of 87% to demethoxylated compounds like phenol and cresols at a guaiacol conversion of 98%. A correlation was found between the oxygen storage capacity of the support (TiO2-P25, TiO2-A HSA, TiO2-R, and MoO3-TiO2) and guaiacol conversion, indicating that this property plays a role in the catalytic cycle. Besides, the demethoxylation of 4-n-propylguaiacol and a realistic guaiacol-rich feed isolated from a representative pyrolysis oil was successfully demonstrated. 87% of the guaiacols present in the feed were converted to demethoxylated phenols with a selectivity of 81%.

Origin of strong metal-support interactions between Pt and anatase TiO2 facets for hydrodeoxygenation of m-cresol on Pt/TiO2 catalysts

Metal/reducible metal oxide catalysts are widely used in hydrodeoxygenation (HDO) reactions for upgrading bio-oil to produce chemicals and fuel components. Under such strong reducing condition, the strong metal-support interaction (SMSI) should take place, however, few work has been devoted to understand the effect of facet of metal oxide on the SMSI and its consequence on HDO performance. Herein, Pt supported on anatase TiO2 with varying dominative exposed facets of (101), (100) and (001) were prepared and tested in HDO of m-cresol at 350 °C and atmosphere H2 pressure. The degree of SMSI of Pt/TiO2 is strongly dependent on the facet of TiO2 when reduced at 350 °C, and the degree of encapsulation decreases following the order of Pt/TiO2-100 > Pt/TiO2-001 > Pt/TiO2-101. The encapsulation correlates well with the reduction degree of TiO2 and the location of oxygen vacancy, which are resulted from varied oxygen vacancy formation and anisotropic diffusion rates in different facets. The intermediate SMSI is achieved on TiO2-001, which creates the maximal density of Pt-Ov-Ti3+ sites at the interfacial perimeter of TiOx/Pt for deoxygenation of m-cresol, resulting in the highest reaction rate and turnover frequency (TOF) while the lowest activation energy (Ea). In contrast, the maximum SMSI on TiO2-100 leads to the lowest deoxygenation rate while the highest Ea. This work provides insight into facet dependent SMSI of Pt/TiO2 and indicates the HDO activity can be finely tailored by tuning the facet of TiO2.

Transition metal-containing MgFe ex-LDH mixed oxides, effective catalysts in the hydrodeoxygenation of benzyl alcohol

Several M-MgFe-LDH precursors were prepared via co-precipitation and then calcined at 500 °C to yield the corresponding M-MgFeO mixed oxide catalysts, which were tested in the hydrodeoxygenation (HDO) of benzyl alcohol. The prepared LDH contained Mg and Fe in a mol ratio of 3:1 and 10 at% M with respect to cations, where M = Ni, Co, Ag and Cu. The Cu-MgFeO mixed oxide gave the best results, therefore we proceeded with the preparation of a Cu(x)-MgFeO series, where x = 2.5–20 at% Cu. The prepared solids were characterized by powder X-ray diffraction, nitrogen adsorption-desorption, temperature-programmed reduction with H2, temperature-programmed desorption of CO2 and energy dispersive X-ray spectroscopy. We studied the influence of the nature of the transition metal M on the activity and selectivity of the catalysts and, for the Cu-containing samples, the influence of Cu loading, reaction time and reaction temperature on their performance in the HDO reaction of benzyl alcohol. With 93.8% conversion and 93.8% selectivity towards toluene at 230 °C, 3 h reaction time and under a hydrogen pressure of 5 atm, the Cu(10)-MgFeO catalyst proved to have the best performance in the studied reaction. Therefore, its stability and reusability were checked. We also proposed a sequence of reactions for the entire HDO process, based on a reverse Mars-van Krevelen mechanism driven by oxygen vacancies formed on the catalyst surface.

Hierarchical pore-trapped and hydrogen-bonded phosphoric acid in Pd-supported zeolite for the efficient aqueous hydrodeoxygenation of lignin derivatives at ambient temperature

Developing an efficient and stable catalyst for the aqueous hydrodeoxygenation (HDO) of lignin derivatives at ambient temperature is highly desirable. Here, a novel Pd/PHS catalyst with the hierarchical structure was facilely constructed. Taking HDO of vanillin (VAN, a typical molecule of lignin derivatives) to 2-methoxy-4-methyl phenol (MMP) as a model reaction, >99% VAN conversion and 98.2% MMP yield can be achieved over Pd/PHS at ambient temperature in a water solvent, outperforming the recent works reported in the literature. We found that the hierarchal zeolitic structure could immobilize acidic P species in Pd/PHS via trapping and hydrogen-bonding, and these P species could greatly accelerate the conversion of reaction intermediate, enhancing the yield of MMP product. Pd/PHS also showed excellent activities in HDO of other lignin derivatives. We think this work will provide a new route to guide the design of stable catalyst for the efficient aqueous HDO of lignin derivatives to high value-added chemicals and biofuels at ambient temperature.

Regulating isomerization of gasoline-alkanes in aqueous-phase hydrodeoxygenation of sorbitol using regenerable Ni@MoOx catalysts

Aqueous-phase hydrodeoxygenation (HDO) has been regarded as an efficient biorefinery strategy for sustainable production of gasoline-alkanes from bio-polyols. However, current research focuses mainly on exploiting noble-metal HDO catalysts to acquire straight-chain C5-C6 alkanes. Herein, the aqueous-phase HDO route was firstly proposed to regulate isomerization of gasoline-alkanes in the sorbitol hydrogenolysis utilizing non-noble Mo-based catalysts in a continuous-flow fixed-bed reactor. The selective reduction removal of hydroxyl groups and isomerization of carbon chains were strongly coupled together for boosting the octane value of gasoline-alkanes over the regenerable Ni@MoOx binary catalysts derived from NiMoO4 spinel. Further characterization studies revealed that the synergism of Ni0 and MoOx played a crucial role in regulating selective dissociation of CO bonds and rearrangement of CC bonds, and suppressing excessive cleavage of CC bonds toward C1-C4 alkanes and CO/CO2. The effects of reaction parameters including reaction temperature, H2-pressure and reduction temperature were also evaluated for manipulating the product distribution between n-alkanes and isoalkanes. After optimization, a high C5-C6 yield of 87.5% with 51.7% of C5-C6 isoalkanes mainly including cycloalkanes was achieved at 280 °C under H2-pressure of 1.0 MPa over the Ni@MoOx catalyst reduced at 500 °C. This catalytic strategy could create new opportunities for producing high-quality biofuels from biomass-derived oxygenated compounds.

Catalytic Hydrodeoxygenation of Vanillin, a Bio-Oil Model Compound over Renewable Ni/Biochar Catalyst

This study aims to examine the hydrodeoxygenation (HDO) of vanillin, an oxygenated phenolic compound present in bio-oil, into creosol. Biochar residue generated when wood is slowly pyrolyzed is utilized as a catalyst support. To improve biochar’s physicochemical properties, H2SO4 (sulfuric acid) and KOH (potassium hydroxide) are used as chemical activators. By means of a wet impregnation method with nickel salt, an Ni/biochar catalyst was prepared and utilized in the HDO of vanillin using a 100 mL Parr reactor, catalyst loading 0.4–0.8 g, temperature 100 °C to 150 °C, hydrogen (H2) pressures of 30 to 50 bar, and a stirring rate of 1000 rpm. The prepared catalysts were characterized with the nitrogen-sorption isotherm technique, carbon dioxide temperature-programmed desorption (CO2-TPD), scanning electron microscopy (SEM) coupled with energy dispersed X-ray analysis (EDX), X-ray diffraction (XRD), and Fourier-transform infrared spectroscopy (FTIR). Based on chemical treatment, Ni/biochar (KOH) pore sizes were found to be dominated by mesopores, with a surface area increase of 64.7% and a volume increase of 65.3%, while Ni/biochar (H2SO4) was mostly microporous and mesoporous, with an area increase of 372.3% and a volume increase of 256.8% in comparison to Ni/biochar (74.84 m2g−1 and 0.095 cm3g−1). Vanillin conversion of up to 97% with 91.17% selectivity to p-creosol was obtained over Ni/biochar catalyst; in addition to being highly selective and active for p-creosol, a plausible fuel, the catalyst was stable after four cycles. Chemical treatments of the biochar support resulted in improved physicochemical properties, leading to improved catalytic performance in terms of vanillin conversion and p-creosol yield in the order Ni/biochar (H2SO4) > Ni/biochar (KOH) > Ni/biochar.

Enhancement of hydrodeoxygenation catalytic performance through the addition of copper to molybdenum oxide-based catalysts

The role of copper promoter and carbon support on the activity, selectivity, and stability of molybdenum oxide was determined for bulk and carbon-supported molybdenum oxide catalysts in phenol hydrodeoxygenation (HDO). The catalytic performance was correlated to the physicochemical properties determined using ICP-AES, XRD, XPS, Raman, TPR, H2O-TPD, and oxygen chemisorption. The results showed that at the studied reaction conditions (atmospheric pressure, 330 ºC, gas phase), the employment of activated carbon as support and the addition of copper improved phenol conversion from 1 (with MoO3) to 28% (with CuMo/C), maintaining high selectivity to benzene (around 100%) while characterization studies evidence the formation of mainly CuMoO4 species in bulk samples and metallic copper, Cu2O, and MoO2 on carbon-supported ones. The incorporation of copper in the molybdenum oxide catalysis promoted the reduction of molybdenum, the creation of oxygen vacancies, and the H• formation, all factors favoring the selective CO bond cleavage. Stability tests of the most active catalysts, Mo/C_H2 and CuMo_H2, showed that deactivation happened, but the direct deoxygenation route remained preferential throughout the reaction time with high selectivity to benzene (up to 98%). Deactivation was related to the lower concentration of available active sites (oxygen vacancies).

Synthesis of high density and low freezing point jet fuels range cycloalkanes with cyclopentanone and lignin-derived vanillins

In this work, a “cyclopentanone-vanillin” strategy was proposed for the preparation of jet fuel range cycloalkanes from lignocellulose-derived ketones and lignin-derived aldehydes via aldol condensation and hydrodeoxygenation (HDO). Ethanolamine lactate ionic liquid (LAIL) exhibited excellent catalytic activity in the aldol condensation of cyclopentanone and vanillin. Desired mono-condensation and bi-condensation products were obtained with yield of 95.2% at 100 °C. It is found that the synergy effects between amino group of ethanolamine and hydroxyl group of lactic acid play a key role in the aldol condensation. The condensation products were converted into cycloalkanes by HDO over 5%Pd/Nb2O5 catalyst. The density of the obtained HDO products is 0.89 g/cm3 and the freezing point is lower than −60 °C. These results suggest that the resulted cycloalkanes can be used as additives to improve the density and low-temperature fluidity of the jet fuels.

INFLUENCE OF BIOMASS PRETREATMENT ON SUBSEQUENT PYROLYSIS AND HYDRODEOXYGENATION IN BIO-BASED TRANSPORT FUELS AND CHEMICALS PRODUCTION: A CRITICAL REVIEW

The present article aims to review the influence of various biomass pretreatments on the production of bio-based transportation fuel and chemicals via pyrolysis and hydrodeoxygenation (HDO). The article includes the influence of different thermochemical pretreatments such as dry torrefaction (DT), wet torrefaction (WT), steam explosion treatment (SET), hot water extraction (HWE), acid treatment (ACT), and alkali treatment (AKT) on bio-oil yield and bio-oil properties. HDO primarily includes dehydration, hydrogenolysis, decarbonylation, and hydrogenation. HDO can be classified based on stages (single and two-stage HDO), reaction pressure (high and low), and hydrogen presence (ex situ and in situ). The recent developments, advantages, and drawbacks associated with different types of HDO processes have been included. The article includes recent studies on designing various catalysts based on HDO conversion of different bio-oil compositions or selective model compounds to targeted bio-based products. The various biomass pretreatments impact the concentration of certain families of organic compounds present in bio-oil. Hence, the present review article also includes recommendations of specific biomass pretreatments for various HDO catalysts designed for selective model compounds or different bio-oil compositions. Few praiseworthy techno-economic analysis (TEA) studies on the influence of different biomass pretreatments on the minimum selling price (MSP) of bio-based products obtained at various production stages have been discussed.