Hydrodeoxygenation Reaction Research Articles

Palladium Nanoparticles Encaged in a Nitrogen‐Rich Porous Organic Polymer: Constructing a Promising Robust Nanoarchitecture for Catalytic Biofuel Upgrading

AbstractRobust nanoarchitectures based on surfactant‐free ultrafine Pd nanoparticles (NPs) (2.7–8.2±0.5 nm) have been developed by using the incipient wetness impregnation method with subsequent reduction of PdII species encaged in the 1,3,5‐triazine‐functionalized nitrogen‐rich porous organic polymer (POP) by employing NaBH4, HCHO, and H2 reduction routes. The Pd‐POP materials prepared by the three different synthetic methods consist of virtually identical chemical compositions but have different physical and texture properties. Strong metal–support interactions, the nanoconfinement effect of POP, and the homogeneous distribution of Pd NPs have been investigated by performing 13C cross‐polarization (CP) solid‐state magic angle spinning (MAS) NMR, FTIR, and X‐ray photoelectron spectroscopy (XPS), along with wide‐angle powder XRD, N2 physisorption, high‐resolution (HR)‐TEM, high angle annular dark field scanning transmission electron microscopy (HAADF‐STEM), and energy‐dispersive X‐ray (EDX) mapping spectroscopic studies. The resulting Pd‐POP based materials exhibit highly efficient catalytic performance with superior stability in promoting biomass refining (hydrodeoxygenation of vanillin, a typical compound of lignin‐derived bio‐oil). Outstanding catalytic performance (≈98 % conversion of vanillin with exclusive selectivity for hydrogenolysis product 2‐methoxy‐4‐methylphenol) has been achieved over the newly designed Pd‐POP catalyst under the optimized reaction conditions (140 °C, 10 bar H2 pressure), affording a turnover frequency (TOF) value of 8.51 h−1 and no significant drop in catalytic activity with desired product selectivity has been noticed for ten successive catalytic cycles, demonstrating the excellent stability and reproducibility of this catalyst system. A size‐ and location‐dependent catalytic performance for the Pd NPs with small size (1.31±0.36 and 2.71±0.25 nm) has been investigated in vanillin hydrodeoxygenation reaction with our newly designed Pd‐POP catalysts. The presence of well‐dispersed electron‐rich metallic Pd sites and highly rigid cross‐linked amine‐functionalized POP framework with high surface area is thought to be responsible for the high catalytic activity and improvement in catalyst stability.

The Influence of Water on the Performance of Molybdenum Carbide Catalysts in Hydrodeoxygenation Reactions: A Combined Theoretical and Experimental Study

AbstractUnderstanding the deactivation of transition‐metal carbide catalysts during hydrodeoxygenation (HDO) reactions is of great importance for improving the production of the second generation fuels from biomass. Based on a combined experimental and theoretical study, we present a mechanistic model for the deactivation of molybdenum carbide catalysts during phenol HDO in the presence of water. At increased water pressure, water molecules preferentially bind to the surface, and active sites are no longer accessible for phenol. In line with first principle calculations, experiments reveal that this process is fully reversible because the reduction of the water partial pressure results in a threefold increase in conversion. The direct deoxygenation of phenol was calculated to be the most favorable pathway, which is governed by the structure of the phenol adsorption complex on the surface at high hydrogen coverage. This is consistent with the experimentally observed high benzene selectivity (85 %) for phenol HDO over MoCx/HCS (hollow carbon spheres) catalyst.

Hydrophobic Pd nanocatalysts for one-pot and high-yield production of liquid furanic biofuels at low temperatures

Liquid furanic hydrocarbons, a class of biomass-based fuels and chemicals, are typically required to achieve moderate product selectivity and yield under harsh conditions (e.g., high temperature and H2 pressure) involving multi-step processes over different catalysts. In this study, a single-step catalytic process was developed for direct conversion of various saccharides to furanic biofuels such as 2,5-dimethylfuran and 2-methylfuran with high yields (>95%) at 110–130°C. The negatively charged hydride (H−) of readily available polymethylhydrosiloxane (PMHS) acting as green H-donor over hydrophobic Pd nanoparticles did not obstruct upstream reactions (e.g., hydrolysis, isomerization and dehydration) for the in situ formation of furanic aldehydes/alcohols from sugars, and could selectively facilitate the subsequent hydrodeoxygenation of carbonyl and hydroxyl groups other than the furanic ring in one pot, as clarified by deuterium-labeling study. Importantly, the unreduced Pd(II) nanocatalysts also exhibited comparable performance in the selective hydrodeoxygenation reaction. Moreover, the catalytic strategy was extended to various carboxides for quantitative production of corresponding furanic/aromatic hydrocarbons at room temperature that were more pronounced than previously reported results, and the optimal Pd/MIL-53(Al) coated with polydimethylsiloxane (Pd/MIL-53(Al)-P) was highly stable with little deactivation and Pd leaching for at least five consecutive cycles.

Transformation of biomass polyol into hydrocarbon fuels in aqueous medium over Ru-Mo/CNT catalyst

The hydrodeoxygenation (HDO) of sorbitol in aqueous medium was performed over CNT supported Ru-Mo bimetallic catalyst. Compared with Ru-Mo/AC, Ru-Mo/CNT showed higher yield and selectivity towards C5/C6 alkanes due to the higher relative rate of CO vs. CC bond cleavage of sorbitol. Based on TEM, XPS and H2-TPR characterizations, the role of CNT in HDO reaction was studied to clarify the likely reasons for the selective CO vs. CC bond cleavage. It is suggested that an increase concentration of MoOx (x<3) species and a smaller metal particle size in the Ru-Mo/CNT catalyst are key factors for the improvement of HDO performance.

Renewable aromatic production through hydrodeoxygenation of model bio-oil over mesoporous Ni/SBA-15 and Co/SBA-15

In present work, ordered mesoporous material SBA-15 was synthesized and used as the support for the dispersion of the nickel and cobalt active metal. XRD, N2 sorption, ICP, H2-TPR and TEM techniques were used for the Ni/SBA-15 and Co/SBA-15 catalysts characterization. Both Ni/SBA-15 and Co/SBA-15 catalysts were tested for the hydrogenation of the typical oxygen-containing molecule present in bio-oil in order to produce the renewable aromatic. Ni/SBA-15 catalyst exhibit much higher catalytic performance as compared with Co/SBA-15 catalyst for the hydrodeoxygenation reaction performance of anisole, but it is also obvious that the Ni/SBA-15 catalyst would inevitably lead to the emergence of partial hydrodeoxygenation product methoxycyclohexane. On the contrary, the direct hydrogenolysis of methoxy-functional group from anisole molecule could prevail over the Co/SBA-15, leading to much higher aromatic selectivity over the Co/SBA-15. Co/SBA-15 could selectively hydrogenolyse the CO bond and could act as the potential hydrodeoxygenation catalyst for aromatic production from the bio-oils because of its high efficiency in the removal of oxygen by a direct hydrogenolysis route.

Effect of Dimethyl Disulfide on Activity of NiMo Based Catalysts Used in Hydrodeoxygenation of Oleic Acid

Alumina supported NiMo catalysts were synthesized. The prepared NiMo catalysts were activated by DMDS in a sulfidation process and characterized. The sulfided NiMo catalysts were next used in hydrodeoxygenation (HDO) of oleic acid in a batch reactor. Afterward, the NiMo catalysts were recovered and used in another set of HDO reactions of oleic acid under the same conditions used in the previous HDO reactions. After the HDO experiments, the active phase and deposited coke on spent catalysts were characterized. The results indicated that higher concentrations of DMDS promoted the production of heptadecane (C17) but had no effect on the production of octadecane (C18). Moreover, the XPS results revealed the promotional effect of DMDS concentration on maintenance of the sulfidity of the catalysts. In addition, the results for the experiments with the second run catalyst revealed a clear deactivation due to increased coke depositions. Furthermore, after two repeated experiments with first run and second run catalysts, it was observed that coke formation decreased when the concentration of DMDS was increased. These results clearly indicate a correlation between the concentration of DMDS and coke formation.

NiMo nitride supported on γ-Al2O3 for hydrodeoxygenation of oleic acid: Novel characterization and activity study

Oxide and nitride phases of NiMo supported on Al2O3 were employed for hydrodeoxygenation (HDO) of oleic acid. Synthesized catalysts were characterized using Raman Spectroscopy, X-ray absorption near edge structure (XANES) and Extended X-ray Absorption Fine Structure (EXAFS). Raman spectroscopy was employed to understand the active-site distribution in NiMo catalysts and elucidate the relation between distribution of active species and catalytic activity. Catalyst evaluation studies showed that NiMo supported on γ-Al2O3 has higher conversion (80%) in comparison to NiMo supported on SBA-15 and HMS during the HDO of oleic acid. Raman maps were obtained for the oxide phase of catalyst and it indicates that the Mo supported on Al2O3 is present as polyanions ([Mo7O24]6− or [Mo8O26]4−). XANES and EXAFS analyses were carried out to understand the oxidation state and co-ordination environment of the catalyst. Occurrence of Mo-Ni and Mo-Mo interactions were proved by the Mo K-edge EXAFS spectra and the bond lengths were determined. The presence of the promoter metal (Nickel) aids in the hydrogenation of oleic acid to stearic acid and direct hydrodeoxygenation, decarboxylation and decarboxylation reactions were observed. The occurrence of polymeric molybdates as confirmed by the Raman spectroscopy leads to the decrease in the availability of active metals for the selective removal of water without breaking the carbon bond leading to the formation of C18H38.

Bifunctional Molybdenum Polyoxometalates for the Combined Hydrodeoxygenation and Alkylation of Lignin-Derived Model Phenolics.

Reductive catalytic fractionation of biomass has recently emerged as a powerful lignin extraction and depolymerization method to produce monomeric aromatic oxygenates in high yields. Here, bifunctional molybdenum-based polyoxometalates supported on titania (POM/TiO2 ) are shown to promote tandem hydrodeoxygenation (HDO) and alkylation reactions, converting lignin-derived oxygenated aromatics into alkylated benzenes and alkylated phenols in high yields. In particular, anisole and 4-propylguaiacol were used as model compounds for this gas-phase study using a packed-bed flow reactor. For anisole, 30 % selectivity for alkylated aromatic compounds (54 % C-alkylation of the methoxy groups by methyl balance) with an overall 72 % selectivity for HDO at 82 % anisole conversion was observed over H3 PMo12 O40 /TiO2 at 7 h on stream. Under similar conditions, 4-propylguaiacol was mainly converted into 4-propylphenol and alkylated 4-propylphenols with a selectivity to alkylated 4-propylphenols of 42 % (77 % C-alkylation) with a total HDO selectivity to 4-propylbenzene and alkylated 4-propylbenzenes of 4 % at 92 % conversion (7 h on stream). Higher catalyst loadings pushed the 4-propylguaiacol conversion to 100 % and resulted in a higher selectivity to propylbenzene of 41 %, alkylated aromatics of 21 % and alkylated phenols of 17 % (51 % C-alkylation). The reactivity studies coupled with catalyst characterization revealed that Lewis acid sites act synergistically with neighboring Brønsted acid sites to simultaneously promote alkylation and hydrodeoxygenation activity. A reaction mechanism is proposed involving activation of the ether bond on a Lewis acid site, followed by methyl transfer and C-alkylation. Mo-based POMs represent a versatile catalytic platform to simultaneously upgrade lignin-derived oxygenated aromatics into alkylated arenes.

Hydrodeoxygenation of vanillin using palladium on mesoporous KIT-6 in vapour phase reactor

Mesoporous KIT-6 was synthesised by using hydrothermal method. Different weight percentage of 1, 3, 5 and 7wt.% of palladium (Pd) was impregnated on KIT-6 by wet impregnation method. All the palladium catalyst was characterized by XRD, ICP-OES, BET, TPR, XPS, FT-IR, DRS-UV and TGA techniques. The morphology of the catalyst was identified by FESEM with EDS and HRTEM analysis. A typical lignin derived model compound (vanillin) was tested for hydrodeoxygenation (HDO) reaction using Pd/KIT-6 catalyst in fixed bed reactor. The activity of the catalyst was evaluated for HDO of vanillin by optimizing temperature (100–300°C) and weight percentage of Pd loading onto KIT-6 (1, 3, 5 and 7wt.%). The conversion of vanillin, selectivity of vanillyl alcohol and p-cresol were confirmed by gas chromatography. The investigation of the study showed that 5wt.% of Pd/KIT-6 catalyst showed 98% conversion of vanillin and 94% selectivity of p-cresol at 300°C for 6h. The time studies were also conducted for all the catalyst in the temperature range of 100 to 300°C revealed that Pd/KIT-6 had higher conversion and maximum selectivity at 6h. The activity of Pd loaded catalyst was comparatively better up to 3 cycles. Selectivity of the vanillyl alcohol was preferably observed by Pd loading (1wt.%) at short time (1h) whereas p-cresol selectivity was observed at long time (6h).

Support effect and metals interactions for NiRu/Al2O3, TiO2 and ZrO2 catalysts in the hydrodeoxygenation of phenol

The bio oil of pyrolysis can be upgraded via hydrodeoxygenation to remove unfavorable characteristics related to high levels of oxygen. Sulfided NiMo and CoMo catalyst have been studied extensively in hydrodeoxygenation. However, significant deactivation may occur, due to the lack of sulfur in the charges or to coke deposition, induced by strong acidic supports. Therefore, development of new catalytic materials with alternative supports and active phases is relevant. In this work, Ni, Ru, and Ni-Ru catalysts were prepared by wet impregnation of Ni(NO3)2·6H2O and Ru(NO)(NO3)3 solutions. Al2O3, TiO2, and ZrO2 were used as supports, evidencing influence on hydrodeoxygenation (HDO) of phenol activity and selectivities. TPR and XPS characterization revealed a promoter effect of ruthenium over Ni reducibility and in some cases, a synergetic effect on catalytic activity in phenol HDO reaction was observed. The metallic ruthenium particles were reduced at low temperatures, and they enhanced reduction of Ni by H2 spillover effect, due to a close contact between metals. Furthermore, TPD-NH3 indicated a possible correlation between catalyst acidity and HDO reaction rate.

Hydrodeoxygenation of glycerol with in situH2 formation over Pt catalysts supported on Fe modified Al2O3: effect of Fe loading

AbstractBACKGROUNDGlycerol hydrodeoxygenation to 1,2‐propanediol is a reaction of commercial and environmental significance. However, the need for hydrogen supply is a main drawback of the process. This study aims at the development of effective catalysts for glycerol hydrodeoxygenation with in situ H2 formed. Pt/Al2O3 and Pt/Fe2O3‐Al2O3 catalysts with different Fe/Pt ratios were synthesized and evaluated. N2 physisorption, XRD, TPR‐H2, TGA and DRIFTS‐CO characterization techniques were used. Main focus was given on catalyst reusability, while a parametric study was also performed.RESULTSFe addition promotes catalysts activity. Characterization showed that there is an electron interaction between Pt and Fe which is responsible for this enhancement. However, Fe/Pt ratio and reduction temperature affect catalyst performance. The increase of Fe loading leads to lower H2 formation rates but also to more stable catalyst performance. The most promising results were achieved over the Fe richer catalyst which exhibited 51.5% 1,2‐propanediol selectivity, 93.8% glycerol conversion, under 3.5 MPa N2, at 250 °C, 1 h and pre‐reduction at 200 °C.CONCLUSIONThe presence of Fe in Pt/Al2O3 catalysts was proved decisive for the combined cycle of glycerol hydrodeoxygenation–aqueous phase reforming. The high activity and the stable performance in aqueous medium may render these materials as suitable catalysts for various liquid phase hydrodeoxygenation reactions. © 2017 Society of Chemical Industry

Geometric and electronic effects of bimetallic Ni–Re catalysts for selective deoxygenation of m-cresol to toluene

Ni–Re/SiO2 bimetallic catalysts were prepared using a co-impregnation method and tested in vapor phase hydrodeoxygenation of m-cresol at 300°C and 1atm H2. In contrast to the use of unselective monometallic Ni/SiO2 for catalyzing deoxygenation, hydrogenation, and CC hydrogenolysis reactions, bimetallic 5%Ni–2.5%Re/SiO2 improved the intrinsic reaction rate of the hydrodeoxygenation reaction by a factor of 6, with the turnover frequency for selective deoxygenation to toluene increased by four times, while that for CC hydrogenolysis to methane was reduced by one-half. Characterization results from X-ray diffraction, Raman, transmission electron microscopy, X-ray photoelectron spectroscopy, infrared spectroscopy of CO adsorption, H2 temperature-programmed reduction, and CO chemisorption indicate that adding Re increased Ni dispersion and resulted in Ni–Re surface alloy formation after reduction. The presence of Re in the surface alloy breaks the continuous Ni surface into smaller ensembles (geometric effect) and reduces the d-band electron density of Ni (electronic effect). Results from density functional theory calculations indicate that the Ni–Re neighboring site is the active site for breaking the CO bond by adsorbing the O atom on Re and the phenyl ring on the neighboring Ni atoms, which facilitates deoxygenation to toluene. The reduced Ni ensemble size inhibits the hydrogenolysis of the CC bond by destabilizing the transition state, whereas the reduction of the electronic density in d states of Ni weakens the adsorption of the phenyl ring, and both contribute to the greatly reduced methane production from successive CC hydrogenolysis.

The hydrodeoxygenation, hydrogenation, hydrodealkylation and ring-opening reaction in the hydrotreating of low temperature coal tar over Ni–Mo/γ-Al2O3 catalyst

The hydrotreatment of low temperature coal tar was carried out in a fixed bed reactor with the Ni–Mo/γ-Al2O3 catalyst. The compounds in the product and feedstock were determined by GC–MS and the effect of temperature, pressure and liquid hourly space velocity (LHSV) were studied based on this analysis. The results show that high temperature had adverse effect on the hydrogenation of aromatics but favorable effect on the ring-opening reaction and hydrodealkylation of aromatics. High pressure and low LHSV was very positive for all these three kinds of reaction of aromatics in coal tar. Most of the aromatics in the products of gasoline originate from the conversion of the monocyclic O-containing compounds. The reactivity of coal tar hydrocracking with the Ni–Mo/γ-Al2O3 catalyst is not very high because γ-Al2O3 is weak acid carrier. The ring-opening seldom occurs at temperatures lower than 380°C. Hydrodeoxygenation is the most important reaction to the upgrading of the coal tar. The gasoline fraction in the product mainly comes from the phenol hydrodeoxygenation in the coal tar hydrogenation process.

Plasma upgrading of 4methylanisole: A novel approach for hydrodeoxygenation of bio oil without using a hydrogen source

Characteristics of pulsed corona discharge were investigated experimentally to combine methyl radical decomposition and hydrodeoxygenation reaction for bio oil upgrading. In contrast to conventional upgrading methods, no hydrogen was used as a feed. The required hydrogen was generated in situ considering the ability of plasma to decompose methyl radicals to hydrogen. Pin to plate corona discharge and 4methylanisole as a model of bio oil were used. Effect of operating and design parameters namely, carrier gas flow rate, pulse repetition frequency, plate electrode diameter, pin number and gap distance were studied on the conversion and selectivity of products. Variation of mentioned parameters can alter the electron and energetic species density and energy which results in improving reaction conversion and product selectivity. The upgrading mechanism of 4ethylanisole was described by a reaction pathway. Demethylation, transalkylation, hydrogenolysis, demethoxylation and methane decomposition are the main chemical reactions. It is worth noting that the optimum condition for methyl decomposition and hydrodeoxygenation reaction are similar for most of design and operating parameters. It was found that the most valuable and abundant products were BTX and phenol with maximum selectivity of about 15% and 46%, respectively. Results indicated that corona discharge plasma can overcome the disadvantages of conventional upgrading process which caused by high pressure hydrogen.

MoS2 monolayer catalyst doped with isolated Co atoms for the hydrodeoxygenation reaction

The conversion of oxygen-rich biomass into hydrocarbon fuels requires efficient hydrodeoxygenation catalysts during the upgrading process. However, traditionally prepared CoMoS2 catalysts, although efficient for hydrodesulfurization, are not appropriate due to their poor activity, sulfur loss and rapid deactivation at elevated temperature. Here, we report the synthesis of MoS2 monolayer sheets decorated with isolated Co atoms that bond covalently to sulfur vacancies on the basal planes that, when compared with conventionally prepared samples, exhibit superior activity, selectivity and stability for the hydrodeoxygenation of 4-methylphenol to toluene. This higher activity allows the reaction temperature to be reduced from the typically used 300 °C to 180 °C and thus allows the catalysis to proceed without sulfur loss and deactivation. Experimental analysis and density functional theory calculations reveal a large number of sites at the interface between the Co and Mo atoms on the MoS2 basal surface and we ascribe the higher activity to the presence of sulfur vacancies that are created local to the observed Co-S-Mo interfacial sites.

Characterization and catalytic properties of molybdenum supported on nano gamma Al2O3 for upgrading of anisole model compound

The conversion of anisole, a prototypical compound representative of lignin-derived bio-oil, was catalyzed by molybdenum supported on nano gamma alumina catalyst in a flow reactor at 623–723K, 8bar pressure and space velocity of 6 (g of anisole)/(g of catalyst×h). Mo supported nano gamma Al2O3 is synthesized by impregnation method and its physicochemical properties are characterized by XRD, FESEM, EDS and BET techniques. For investigation and evaluation of the support effect, regular gamma support is used for synthesis a catalyst at optimum loading in order to compare the performance of nano gamma alumina supported catalyst. Catalytic upgrading of anisole over Mo supported nano gamma Al2O3 represented that this type of catalyst is active to form benzene by hydrodeoxygenation (HDO) reaction, phenol by hydrogenolysis, 2-methylphenol by transalkylation, to 2,6-dimethylphenol and 2,3,5,6-tetramethylphenol by alkylation. Experimental analysis revealed that increasing the Mo loading to 20% enhances the anisole conversion, however high metal loadings leads to metal particles agglomeration and as a result, the surface area will decrease. Also increasing temperature enhances conversion of anisole. Catalytic investigations indicated that nano gamma alumina supported catalyst exhibited higher catalytic activity than regular gamma alumina supported catalyst.

Hydrodeoxygenation of model compounds on sulfided CoMo/γ-Al2O3 and NiMo/γ-Al2O3 catalysts; Role of sulfur-containing groups in reaction networks

Hydrodeoxygenation reactions were studied with model compounds on sulfided hydrotreating CoMo/γ-Al2O3 and NiMo/γ-Al2O3 catalysts with and without adding a sulfur-containing compound into the reaction mixtures. Clear differences were observed in the behaviour of the model compounds. The addition of H2S improved the reactivity of methyl heptanoate and guaiacol with the formation of methanethiol but decreased that of phenol. The presence of sulfur compounds in the gas phase affected also the selectivities reducing the hydrogenation activity of the catalysts and shifting the C7/C6 hydrocarbon distribution from methyl heptanoate. Thus sulfur groups present on the catalyst surface form the key components for the reactions. The reaction network of methyl heptanoate can be described with two types of reactions: reactions with only hydrogen addition and reactions with the contribution of the surface SH− groups. We propose that the ability of the nucleophilic SH− groups to interact with model compounds is a primary factor influencing the initial overall reactivity of the starting compounds. Furthermore, the increasing amount of SH− groups directed the distribution of hydrocarbons towards C6 instead of C7 hydrocarbons from methyl heptanoate by accelerating the decarbonylation/decarboxylation reaction and the 1-hexanethiol formation.

Process modeling of hydrodeoxygenation to produce renewable jet fuel and other hydrocarbon fuels

The focus of this work is to model the hydrodeoxygenation process to produce renewable jet fuel and co-products from low-input oilseeds, specifically camelina, carinata (non-edible oil) and used cooking oil (UCO), taking into account the fatty acid compositions by incorporating the stoichiometric hydrodeoxygenation reactions. This methodology provides insight into the effect of feedstock composition and hydrodeoxygenation reactions upon product yields, product distribution, hydrogen consumption and process utilities. The resulting product slates, hydrogen gas and utility demands are specific to each of the camelina, carinata and UCO feedstocks.The yield of kerosene-range alkanes ranged from 53 to 54% of the incoming oil, with 13–14% diesel range alkanes, 13–15% naphtha, and 7–9% liquefied petroleum gas, depending upon the fatty acid composition. The hydrogen consumption rate ranged from 26 to 30kg per tonne of incoming oil, depending upon the degree of bond unsaturation. Thermal energy demand is 2.8GJ/tonne oil when processing used cooking oil, versus 5.2 and 5.7GJ/tonne of oil for carinata and camelina, respectively, owing to the additional energy required for oil extraction. Electricity demand was 73kWh/tonne oil for UCO, versus 170 and 227kWh/tonne oil for carinata and camelina.

Influence of Solvent on Liquid Phase Hydrodeoxygenation of Furfural-Acetone Condensation Adduct using Ni/Al2O3-ZrO2 Catalysts

Influence of water and acidic protic solvent on hydrodeoxygenation (HDO) of the furfural-acetone adduct (FAA) over Ni/Al2O3-ZrO2 (NiAZ) catalysts were investigated. The HDO of FAA was carried out in a batch reactor at 150°C for 8 hours. The NiAZ catalysts were home-made catalysts which were prepared by wet impregnation method with 10 and 20% nickel loading. The HDO reaction of FAA using 10NiAZ in water at 150°C gave alkane and oxygenated hydrocarbons at 31.41% with selectivity over tridecane (C13) in 6.67%. On the other hand, a reaction using acetic acid:water (1:19 v/v) in similar reaction condition gave only oxygenated compounds and hydrocracking product (C8-C10). The formation of tridecane (C13) was proposed by hydrogenation of C=O and C=C followed by decarboxylation without hydrocracking process. The presence of water facilitated decarboxylation mechanism by stabilized dehydrogenated derivatives of FAA.

Catalytic hydrothermal liquefaction (HTL) of biomass for bio-crude production using Ni/HZSM-5 catalysts

Hydrothermal liquefaction (HTL) is an effective method that can convert biomass into bio-crude, but direct use of bio-crude derived from biomass HTL remains a challenge due to the lower quality. In this study, bifunctional Ni/HZSM-5 catalysts and zinc hydrolysis were combined to produce upgraded bio-crude in an in-situ HTL process. The K 2 CO 3 and HZSM-5 catalysts with different Ni loading ratios were tested. The effects of different catalysts on the yield and quality of bio-crude and gas were investigated. The results indicated that the catalysts improved bio-crude and gas yields, compared to pine sawdust liquefaction without catalyst. The catalysts reduced the contents of undesirable oxygenated compounds such as acids, ketones, phenols, alcohols and esters in bio-crude products while increased desirable hydrocarbons content. K 2 CO 3 produced highest bio-crude yield and lowest solid residue yield among all catalysts. Compared to parent HZSM-5 catalyst, bifunctional Ni/HZSM-5 catalysts exhibited higher catalyst activity to improve quality of upgraded bio-crude due to its integration of cracking and hydrodeoxygenation reactions. 6%Ni/HZSM-5 catalyst produced the bio-crude with the highest hydrocarbons content at 11.02%. This catalyst can be a candidate for bio-crude production from biomass HTL.