Aqueous-phase Hydrodeoxygenation Research Articles

Aqueous Phase Hydrodeoxygenation of Phenol on Hβ Zeolite Supported NiCo Alloy Catalysts

Aqueous Phase Hydrodeoxygenation of Phenol on Hβ Zeolite Supported NiCo Alloy Catalysts

In situ aqueous phase hydrodeoxygenation of methyl palmitate on Ni–Co alloy particles embedded in mesoporous carbon hollow sphere catalysts

Ni–Co alloy particles embedded in mesoporous carbon hollow sphere (NiCo@MCHS) catalysts promote the internal diffusion and in situ aqueous phase hydrodeoxygenation of methyl palmitate.

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.

Robust MOF-derived carbon-supported bimetallic Ni-Co catalysts for aqueous phase hydrodeoxygenation of vanillin.

Currently, rapidly increasing consumption of fossil resources has propelled the upgrading of biomass as an alternative and sustainable technology to produce important chemicals and bio-oils. In this regard, the rational design of low-cost and robust supported metal-based catalysts that exhibit excellent catalytic hydrodeoxygenation (HDO) performance for the conversion of biomass is quite necessary. Herein, we developed hierarchical flower-like nitrogen-doped carbon layer-coated bimetallic Ni-Co nanoparticles, which were distributed over the carbonaceous matrix (NixCo@NC@C), via a metal-organic framework (MOF) ZIF-67 precursor approach, assisted by the etching of Ni2+ ions, hydrothermal treatment together with glucose, and following carbonization processes. The as-fabricated Ni3Co@NC@C catalyst bearing a 3 : 1 Ni/Co molar ratio showed a superior catalytic HDO activity towards aqueous phase HDO of vanillin to other bimetallic NiCo catalysts with different Ni/Co molar ratios under mild reaction conditions, along with a 100% selectivity to 2-methoxy-4-methylphenol at a full vanillin conversion, despite its smaller number of exposed metallic sites. It was revealed that over the Ni3Co@NC@C catalyst, the surface abundant defective oxygen vacancies and electron-rich Co0 species were conducive to the adsorption and activation of vanillin and the reaction intermediate, thereby giving rise to the outstanding catalytic activity. Moreover, for Ni3Co@NC@C, the adequate protection effect of surface carbon layers, as well as the unique hierarchical flower-like microstructure, could significantly inhibit the leaching of active metal species in the reaction medium, thereby leading to high structural stability. The present findings afford a promising strategy for constructing low-cost and robust carbon-supported bimetallic catalysts for the HDO of lignin-derived derivatives.

Aqueous Phase Hydrodeoxygenation of Lignin-Derived Phenols Over Al2o3-Sio2 Microspheres Supported Rumn Multifunctional Catalyst: Synergic Effect Among Ru, Mn and Al2o3-Sio2 Support

Aqueous Phase Hydrodeoxygenation of Lignin-Derived Phenols Over Al2o3-Sio2 Microspheres Supported Rumn Multifunctional Catalyst: Synergic Effect Among Ru, Mn and Al2o3-Sio2 Support

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%.

Carbon-coated Ni-Co alloy catalysts: preparation and performance for in-situ aqueous phase hydrodeoxygenation of methyl palmitate to hydrocarbons using methanol as the hydrogen donor

Carbon-coated Ni-Co alloy catalysts: preparation and performance for in-situ aqueous phase hydrodeoxygenation of methyl palmitate to hydrocarbons using methanol as the hydrogen donor

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

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

Controlling Transformation of Sorbitol into 1-Hexanol over Ru-MoOx/Mo2C Catalyst via Aqueous-Phase Hydrodeoxygenation

Controlling Transformation of Sorbitol into 1-Hexanol over Ru-MoO<i>_x</i>/Mo₂C Catalyst via Aqueous-Phase Hydrodeoxygenation

Selective aqueous phase hydrodeoxygenation of erythritol over carbon-supported Cu catalyst prepared from ion-exchange resin

For the selective hydrodeoxygenation (HDO) of erythritol to butanediols, a carbon-supported Cu catalyst (Cu/C) with small copper particles (diameter of 14.9 nm) at high metal loading (66.9 wt%) was prepared using a weakly acidic cation-exchange resin as the carbon support precursor. Compared with the activated carbon-supported Cu catalyst prepared by the impregnation method, Cu/C showed high activity, high butanediol selectivity, and high sintering resistance. The effects of reaction temperature, reaction time, and initial hydrogen pressure on erythritol conversion and butanediol selectivity were also studied. The highest butanediol yield of 18.3 C-mol% at a butanediol selectivity of 54 C-mol% was realized over the Cu/C catalyst at 180 °C and 1.8 MPa H2 for 240 h. Moreover, the HDO of erythritol to butanediols over Cu/C proceeded mainly via 1,2,4-butanetriol. Vicinal diols such as 1,2-butanediol and 2,3-butanediol were favorably formed over the Cu surface because the substrates were adsorbed on Cu via the two vicinal OH groups and these OH groups did not participate in the HDO reactions.

In situ aqueous phase hydrodeoxygenation of methyl palmitate to hydrocarbons on Ni catalyst derived from the reduction of LaNiO3 perovskite

A series of Ni–La–O-T catalysts (T-calcination temperature) were prepared via the sol–gel process followed by the calcination. They were tested for in situ aqueous phase hydrodeoxygenation (HDO) of methyl palmitate using methanol as hydrogen donor. In the calcined samples, NiO and La2O2(CO3) formed in Ni–La–O-550 and Ni–La–O-650. Apart from NiO and La2O2(CO3), there was LaNiO3 perovskite in Ni–La–O-750. Only LaNiO3 perovskite existed in Ni–La–O-800. After the reduction at 650 °C, metallic Ni and La2O3 appeared in all the catalysts. During in situ HDO, decarbonylation/decarboxylation was dominating, accompanying with the C–C bond hydrogenolysis and aqueous phase reforming of alkanes. H2 was generated from not only the aqueous phase reforming of methanol but also that of alkanes. Liquid C6–C16 alkanes were produced and C15 alkane was main product. Among the catalysts, Ni–La–O-750 afforded the highest activity for deoxygenation, C–C bond hydrogenolysis and aqueous phase reforming. The reaction temperature, reaction time, water and methanol loadings remarkably affected the products distribution. At a suitable condition, the yield of C6–C16 alkanes reached 71.1% on Ni–La–O-750. Additionally, Ni–La–O-750 was also very active for in situ HDO of methyl palmitate without methanol, however, the C–C bond hydrogenolysis was more serious.

Direct synthesis of a jet fuel range dicycloalkane by the aqueous phase hydrodeoxygenation of polycarbonate

A jet fuel range high-density C15 dicycloalkane was directly synthesized in a high overall yield (∼90%) by the aqueous phase hydrodeoxygenation of polycarbonate.

Conversion of phenol to cyclohexane in the aqueous phase over Ni/zeolite bi-functional catalysts

A series of Ni/HZSM-5 and Ni/HIM-5 bi-functional catalysts were synthesized and applied to the aqueous-phase hydrodeoxygenation (HDO) of phenol. The Ni dispersibility and particle sizes were shown to be directly related to the porosity and crystal sizes of the parent zeolites, which further influenced the catalytic performances. The large pores and small crystal sizes of the parent zeolites were beneficial for dispersing Ni and forming small Ni particles, and the corresponding Ni/zeolite catalyst exhibited a higher phenol conversion and selectivity towards hydrocarbons. Importantly, the Ni/HIM-5 bi-functional catalyst exhibited a high activity (98.3%) and high selectivity for hydrocarbons (98.8%) when heated at 220°C for 1 h and is thus a new potential catalyst for the HDO of phenolics to form hydrocarbons in the aqueous phase.

Biofuel Synthesis from Sorbitol by Aqueous Phase Hydrodeoxygenation over Bifunctional Catalysts: In-depth Study of the Ru–Pt/SiO2–Al2O3 Catalytic System

The catalytic performances of Ru–Pt/SiO2–Al2O3 catalysts synthetized by three methods (co-impregnation (CI), successive impregnations (SI) and redox deposition (CR)) were compared for their sorbitol transformation to hexane under hydrothermal conditions. The existence of Pt–Ru interaction was demonstrated by TEM-EDX only on SI and CR samples, with a PtRu alloy suspected by XRD and XPS. The chemical nature of the Ru species differed according to the synthesis method with the presence of Ru4+ species on SI–(Ru–Pt) and CR catalysts. The SI–(Ru–Pt)/SiO2–Al2O3 system displayed the best metal–acid function balance leading to the highest selectivity to hexane. The study of the reactivity of isosorbide and 2,5-dimethylfuran intermediates highlighted that the first one was poorly reactive compared to the second one, and the latter was selectively convertible to hexane. The synergy effect on SI– (Ru–Pt)/SiO2–Al2O3 catalyst was attributed to the presence of small-sized bimetallic particles favoring an electronic exchange from Ru to Pt, and increasing the formation of 2,5-dimethylfuran.

Hydrodeoxygenation of lignin-derived phenols to produce hydrocarbons over Ni/Al-SBA-15 prepared with different impregnants

Non-noble metal(s)-based mesoporous catalysts are one of the promising catalysts for aqueous phase hydrodeoxygenation of lignin-derived phenols to produce hydrocarbons. In this paper, Ni/Al-SBA-15 was prepared through incipient wetness impregnation method and the performance of eugenol hydrodeoxygenation over Ni/Al-SBA-15 was studied. The effect of incipient wetness impregnant on the performance of eugenol hydrodeoxygenation over Ni/Al-SBA-15 was investigated. The materials were characterized by XRD, N2-sorption, TEM, FTIR, Py-FTIR, XRF and ICP-MS. In comparison with the traditional incipient wetness impregnation using water as solvent, the activity of Ni/Al-SBA-15 was significantly improved by using ethanol as solvent during the process of incipient wetness impregnation. For Ni/Al-SBA-15, the quantity of total acid was decreased after loading nickel species which was mainly due to the decrease of Lewis acid sites. The strength of Lewis acid in Ni/Al-SBA-15 prepare with ethanol as impregant was enhanced. The yields of propyl cyclohexane and propylbenzene from aqueous phase hydrodeoxygeation of eugenol over Ni/Al-SBA-15-E were increased. The super catalytic behavior of Ni/Al-SBA-15-E was attributed to the synergistic effect between the stronger Lewis acid sites and the intact framework structure of Ni/Al-SBA-15-E.

Catalytic Transfer Hydrogenation of Biomass-Derived Substrates to Value-Added Chemicals on Dual-Function Catalysts: Opportunities and Challenges.

Aqueous-phase hydrodeoxygenation (APH) of bioderived feedstocks into useful chemical building blocks is one the most important processes for biomass conversion. However, several technological challenges, such as elevated reaction temperature (220-280 °C), high H2 pressure (4-10 MPa), uncontrollable side reactions, and intensive capital investment, have resulted in a bottleneck for the further development of existing APH processes. Catalytic transfer hydrogenation (CTH) under much milder conditions with non-fossil-based H2 has attracted extensive interest as a result of several advantageous features, including high atom efficiency (≈100 %), low energy intensity, and green H2 obtained from renewable sources. Typically, CTH can be categorized as internal H2 transfer (sacrificing small amounts of feedstocks for H2 generation) and external H2 transfer from H2 donors (e.g., alcohols, formic acid). Although the last decade has witnessed a few successful applications of conventional APH technologies, CTH is still relatively new for biomass conversion. Very limited attempts have been made in both academia and industry. Understanding the fundamentals for precise control of catalyst structures is key for tunable dual functionality to combine simultaneous H2 generation and hydrogenation. Therefore, this Review focuses on the rational design of dual-functionalized catalysts for synchronous H2 generation and hydrogenation of bio-feedstocks into value-added chemicals through CTH technologies. Most recent studies, published from 2015 to 2018, on the transformation of selected model compounds, including glycerol, xylitol, sorbitol, levulinic acid, hydroxymethylfurfural, furfural, cresol, phenol, and guaiacol, are critically reviewed herein. The relationship between the nanostructures of heterogeneous catalysts and the catalytic activity and selectivity for C-O, C-H, C-C, and O-H bond cleavage are discussed to provide insights into future designs for the atom-economical conversion of biomass into fuels and chemicals.

Upgrading Biocrude of Grindelia Squarrosa to Jet Fuel Precursors by Aqueous Phase Hydrodeoxygenation

AbstractBio‐jet fuel is increasingly attracting attention in attempts to reduce the environmental impacts of aviation fuels. Feedstocks like camelina, jatropha and algae have been extensively studied, and exhibit fair performance in producing low‐density hydrocarbon biofuels, mainly from triglyceride lipids. Grindelia squarrosa is a promising feedstock since the primary diterpenoid, grindelic acid with the branched tricyclic structure, is the major component in its biocrude. Herein, a heterogeneous bi‐functional catalyst, palladium with the reductive properties supported on tungstate zirconia with acidic properties and good stability in hydrothermal media, was used for the conversion of Grindelia squarrosa biocrude to potential bio‐jet fuels. Different solid acid catalyst supports and a variety of reaction conditions, such as temperature, catalyst loading, hydrogen pressure, and reaction time, were systematically investigated. At the optimum conditions, the oxygen content deceased from 18.1 % in the Grindelia squarrosa biocrude feedstock to 5.6 % in the final product, and is ready for further industrial treatment. The upgrading method utilized in this work can produce jet fuel precursors for synthesizing high‐density cyclic hydrocarbons.

Highly Dispersed Copper Nanoparticles Supported on Activated Carbon as an Efficient Catalyst for Selective Reduction of Vanillin.

Highly dispersed copper nanoparticles (Cu NPs) supported on activated carbon (AC) are effectively synthesized by one-pot carbothermal method at temperature range of 400-700 °C. The X-ray diffraction, transmission electron microscopy, X-ray photoelectron spectroscopy, and Brunauer-Emmett-Teller analysis reveal that Cu NPs with diameters of 20-30 nm are evenly anchored in carbon matrix. The 15 wt%-Cu/AC-600 catalyst (derived at 600 °C) exhibits best bifunctional catalysis of aqueous-phase hydrodeoxygenation (HDO) and organic-phase transfer-hydrogenation reaction (THR) to selectively transform vanillin to 2-methoxy-4-methylphenol (MMP). In HDO of vanillin, the as-prepared catalyst achieves a 99.9% vanillin conversion and 93.2% MMP selectivity under 120 °C, 2.0 MPa H2 within 5 h. Meanwhile, near-quantitative vanillin conversion and 99.1% MMP selectivity are also obtained under 180 °C within 5 h in THR of vanillin by using 2-propanol as hydrogen donor. The transforming pathways of vanillin are also proposed: vanillin is transformed into MMP via intermediate of 4-hydroxymethyl-2-methoxyphenol in HDO case and by direct hydrogenolysis of vanillin in THR course. More importantly, the activity and the selectivity do not change after 5 cycles, indicating the catalyst has excellent stability. The Cu-based catalyst is relatively cheap and preparation method is facile, green, and easy scale-up, thus achieving a low-cost transformation of biomass to bio-oils and chemicals.

Synergistic effects of Nb2O5 promoter on Ru/Al2O3 for an aqueous-phase hydrodeoxygenation of glycerol to hydrocarbons

Synergistic effects of niobium oxide (Nb2O5) on the Ru/Al2O3, where the alumina had boehmite phases prepared by sol-gel method with subsequent co-impregnation of bimetallic Ru-Nb, were investigated for an aqueous-phase hydrodeoxygenation (APH) as well as aqueous-phase reforming (APR) reaction of glycerol to form gaseous hydrocarbons and hydrogen with useful liquid-phase glycols such as ethylene and propylene glycols. The promoting effects of the Nb2O5 on the prototype Ru/Al2O3 were mainly attributed to the stabilized boehmite structures with the help of an incorporation of niobium oxides, which largely increased the catalytic activity and stability through less aggregations of smaller Ru nanoparticles. At an optimal Nb/Ru molar ratio of ∼1, the much smaller Ru nanoparticles were highly dispersed on the Nb-incorporated alumina matrices on the hexa-coordinated Al3+ sites selectively even after hydrothermal aqueous-phase reactions. The highly dispersed Ru nanoparticles on the Lewis acid sites of the boehmite phase of Al2O3 surfaces showed a facile reducibility and larger metallic Ru surface area with less formations of inactive hard coke precursors. It was mainly originated from the preferential presence of the reduced metallic Ru nanoparticles on the surfaces of the acidic Nb2O5-modified boehmite, which can strongly anchor the active Ru metals with their smaller sizes.

Glycerol hydrodeoxygenation to 1,2-propanediol catalyzed by CuPd/TiO2-Na

Copper-palladium bimetallic catalysts supported on TiO2 were developed for the aqueous phase hydrodeoxygenation (HDO) of glycerol. Na-promoted bimetallic catalysts had higher activity than monometallic catalysts while maintaining high 1,2-propanediol (1,2-PDO) selectivity (76–93%) characteristic of Cu catalysts. The best results were obtained with CuPd/TiO2-Na. At 220°C and 0.7MPa H2 the initial turnover frequency (TOF based on Cu+Pd sites) was 0.14s−1; the selectivity to 1,2-PDO reached 85%. Characterization of the samples was performed by H2-temperature programed reduction (H2-TPR), X-ray diffraction and high-resolution electron microscopy (HRTEM) plus selected area electron diffraction (SAED), and their results were consistent with the formation of CuPd alloy nanoparticles with their surface enriched in Cu, hence explaining the high selectivity to 1,2-PDO of the bimetallics. The increased activity of the Pd-Cu bimetallic catalysts stems from the significantly smaller average diameter of the CuPd alloy nanoparticles when compared with the Cu or Pd nanoparticles of the monometallic catalysts. Besides the effect upon the nanoparticle structure, Pd promoted HDO in part by the activation of glycerol aqueous phase reforming to produce H2 at the surface level. Cu was stabilized in the bimetallic samples by the formation of the alloy with Pd and by the presence of Na in the catalyst. As a result, CuPd/TiO2-Na can be reused while maintaining high stable activity and 1,2-PDO selectivity. The HDO reaction proceeds through the formation of 1-hydroxy-2-propanone (acetol), followed by its hydrogenation to form 1,2 PDO. Formation of acetol or an acetol-like surface intermediate presumably occurs on support sites, whereas the hydrogenation to 1,2-PDO occurs on the metal sites. The first step is enhanced when basic sites are added to the support, while the hydrogenation step on Cu sites is improved by raising the H2 pressure and/or by the formation of H2 via reforming on Pd sites.