Hydrodeoxygenation Performance Research Articles

Preparation of Ni/SiO2–Al Catalyst and Its Performance for m-Cresol Hydrodeoxygenation

Preparation of Ni/SiO2–Al Catalyst and Its Performance for m-Cresol Hydrodeoxygenation

Synergistic effect between acidity and metallicity on the methyl laurate hydrodeoxygenation performance for Ni-based catalyst

Sulfur-free Ni/γ-Al2O3 and Ni-based bimetallic Ni5X5/γ-Al2O3 (X = Cu, Fe, Zn, Co, and Mn) catalysts prepared by impregnation method were characterized by H2-TPR, XRD, BET, NH3-TPD, Py-IR, TEM, ESEM, XPS, and H2-TPD. The effects of transition metal on the physicochemical properties and methyl laurate hydrodeoxygenation (HDO) performance of the studied Ni-based catalysts were also investigated. The results showed that all the prepared Ni-based catalysts have mesoporous structure and large specific surface area (>130 m2 g−1), the Ni, Cu, Fe, Zn, Mn, and Co species were dispersed highly over the Ni5X5/γ-Al2O3 catalysts. The introduction of transition metal has a remarkable influence on the reducibility of Ni species and obviously improve the low temperature “absorption-desorption” performance of the studied Ni-based catalysts to H2 molecules. All the studied Ni-based catalysts can preferentially catalyze the methyl laurate to occur decarbonylation/carboxyl (DCO) reaction to produce C11 alkanes, because of the synergy effects between metal centers and acid sites. The carbonyl and/or bridge oxygen atoms in methyl laurate can be activated by electrophilic acidic sites, the intermediate products can be attacked by the reactive H atoms formed on the metal centers. The selectivity of the hydrogenation products including C11, C12, and oxygenated compounds are obviously affected by transition metal additives. Methyl laurate conversion and C11 alkanes selectivity can reach 99.8 and 87.3 % at 400°Ϲ, respectively. In addition, the Ni5Cu5/γ-Al2O3 catalyst possesses acceptable cycle and regeneration performances.

Toward the Rational Design of More Efficient Mo2C Catalysts for Hydrodeoxygenation-Mechanism and Descriptor Identification.

Viable alternatives to scarce and expensive noble-metal-based catalysts are transition-metal carbides such as Mo and W carbides. It has been shown that these are active and selective catalysts in the hydrodeoxygenation of renewable lipid-based feedstocks. However, the reaction mechanism and the structure-activity relationship of these transition-metal carbides have not yet been fully clarified. In this work, the reaction mechanism of butyric acid hydrodeoxygenation (HDO) over molybdenum carbide (Mo2C) has been studied comprehensively by means of density functional theory coupled with microkinetic modeling. We identified the rate-determining step to be butanol dissociation: C4H9*OH + * → C4H9* + *OH. Then we further explored the possibility to facilitate this step upon heteroatom doping and found that Zr- and Nb-doped Mo2C are the most promising catalysts with enhanced HDO catalytic activity. Linear-scaling relationships were established between the electronic and geometrical descriptors of the dopants and the catalytic performance of various doped Mo2C catalysts. It was demonstrated that descriptors such as dopants' d-band filling and atomic radius play key roles in governing the catalytic activity. This fundamental understanding delivers practical strategies for the rational design of Mo2C-based transition-metal carbide catalysts with improved HDO performance.

Efficient solvent-free hydrodeoxygenation of bio-lipids over bifunctional NiW catalyst: Manipulations of surface-active sites by thermal pretreatment

The effect of thermal pretreatment on the bifunctional NiW catalyst and its hydrodeoxygenation (HDO) performance on oleic acid were investigated. Increasing the calcination temperature (CT) not only led to the growth of NiW particles, but caused the migration of Ni to the surface that resulted in the segregation of W. The reduction temperature (RT) was also able to tune the catalyst surface composition. A lower RT (600 °C) led to a W-rich surface, while a higher one (700 °C) interestingly resulted in a Ni-rich surface. To this end, the ratio of surface-active sites, i.e., the partially reduced W species (Wδ+) to Ni0 ones (Wδ+/Ni0), was manipulated. The highest Wδ+/Ni0 ratio of 2.6 was reached at the CT and RT of 550 °C and 700 °C, respectively, which contributed to an impressively high solvent-free deoxygenation of 95.1% at only 300 °C. The deoxygenation rate (rdeoxy.) was much higher than that of the reported non-precious catalysts, even comparable to the precious ones. Additionally, a high catalyst durability was found on non-acid feedstocks like triglycerides, long-chain alcohols, etc., but an acidic substrate like oleic acid tended to leach the loaded metals that eventually lessened the HDO activity.

Hydrodeoxygenation Performance of Lignin-Derived Phenolics to Cycloalkanes: Insights into the Crystal Structures of the Nb2O5 Support

Hydrodeoxygenation Performance of Lignin-Derived Phenolics to Cycloalkanes: Insights into the Crystal Structures of the Nb₂O₅ Support

Hydrodeoxygenation of stearic acid over zeolite–MOF composite-supported Pt catalysts

Herein, we report the synthesis of a series of zeolite-porous metal–organic framework (MOF) (ZM) composites with different Pt loadings via a two-step approach, in which –COOH functionalized ZSM-5 particles were added during the formation of MIL-100(Fe) (Materials Institute Lavoisier) by a microwave-assisted solvothermal method. The acidity of the ZM composites was significantly improved compared to that of the parent materials, and the highest acidity was observed for the ZM2-based catalyst. This ZM composite-supported Pt (Pt/ZM) catalyst was investigated as a promising candidate for the selective hydrodeoxygenation (HDO) of stearic acid as a fatty acid model compound. The effect of zeolite/MOF ratio and Pt content on the catalytic behavior was also evaluated. As a result, the 3% Pt/ZM2 catalyst showed a conversion efficiency of 92% for the stearic acid HDO with a hydrocarbon selectivity of 10–11 times higher than that of the original Pt/MIL-100 (Fe). In addition, 3% Pt/ZM2 catalyst exhibited stable catalytic performance for stearic acid HDO during the recycle runs. The optimized Pt/ZM catalyst showed high thermal and catalytic stability, as well as high product yield.

Transition metal carbide catalysts for Upgrading lignocellulosic biomass-derived oxygenates: A review of the experimental and computational investigations into structure-property relationships

Transition metal carbide (TMC) catalysts, due to their noble metal like characteristics,have emerged as potential candidates for the hydrodeoxygenation (HDO) of biomass derived species, including the pyrolysis product bio-oil. However, the selectivity for deoxygenation, excessive hydrogenation and stability under operating conditions,remain as key challenges. Hence, this paper presents a comprehensive review of the state of the art with regard to (i) the preparation and structure of TMCs, (ii) characterization of active sites on TMCs and (iii) fundamental knowledge of the reaction mechanisms/pathways and associated energetics of HDO of model compounds which are present in biomass derived bio-oil. We believe that this fundamental knowledge will greatly assist researchers to systematically modify the composition and structure of TMCs to optimize their HDO performance.

Catalytic conversion of biomass


 Resource scarcity and increasing climate change have brought attention to the need for sustainable and renewable resources. Biomass is an earth-rich material with great potential as a feedstock for alternative fuels and chemicals. In order to utilize biomass efficiently, such biopolymers must be depolymerized and converted into key structural units and/or target products, and biological or chemical catalysts are often used for fast and energy-efficient reactions. This paper presents recent advances in the catalytic conversion of biomass into biofuels and value-added products. Hydrodeoxygenation is an important and unique method for converting biomass and biomass-derived oxygenated chemicals into high value-added chemicals and fuels. However, the synthesis of catalysts with excellent hydrogenation and hydrodeoxygenation performance at the same time remains a great challenge.

Effect of Ni, Mo and W on hydrothermal co-liquefaction of macroalgae and microalgae: Impact on bio-crude yield and composition

The co-hydrothermal liquefaction of macroalgae (Enteromorpha Clathrata) and microalgae (Chlorella Vulgaris) with metal catalyst was conducted at the temperature of 350 °C. Ni/MCM-41, Mo/MCM-41 and W/MCM-41 catalysts were used to investigate the role of catalyst on the bio-oil yield and composition distribution during hydrothermal liquefaction. the physicochemical properties of MCM-41, Ni/MCM-41, Mo/MCM-41, and W/MCM-41 were investigated by SEM, XRD, XPS, and NH3-TPD. These catalysts all reduced the production of bio-oil but improved the quality of bio-oil. The results of ultimate analysis showed that Ni/MCM-41 revealed high performance in hydrodeoxygenation and upgrading of bio-oil, and had the highest HHV. Mo/MCM-41 displayed an achievement in increasing the content of hydrocarbons (23.04%) and reducing the relative content of acid products in bio-oil. The W/MCM-41 had the most obvious effect on increasing the content of ester compounds and reducing the content of N-containing compounds in bio-oil.

N-doped hollow carbon nanospheres anchored Pd NPs for mild selective hydrodeoxygenation of bio-models

Hydrodeoxygenation (HDO) is a promising approach for the synthesis of renewable fuels and chemicals, while the design and preparation of high-performance catalysts in this field remain a challenge. Herein, a series of hollow carbon nanospheres anchored Pd nanoparticles (NPs) catalysts with different nitrogen doping contents (Pd/HCAFR-X, X=0.3, 0.6, 0.9) were prepared for the selective HDO of bio-models compound under mild conditions. Notably, the Pd/HCAFR-0.6 catalyst exhibited excellent catalytic performance for the acetophenone (APh) HDO in polymethylhydrosiloxane (PMHS) at 50 °C for 3 h, and the yield of ethylbenzene was close to 99%. The good catalytic results can be mainly attributed to the unique hollow carbon nanospheres with abundant defects provided by appropriate nitrogen doping content. The large surface area and hierarchical porous structure of the hollow carbon framework offered more active sites, which promoted the transportation of species on the catalyst. In addition, the nitrogen doping amount can adjust the defect degree of the hollow carbon nanospheres, stabilize the dispersion and anchoring of Pd NPs, and then induce the transfer of local electrons. Furthermore, the Pd/HCAFR-0.6 catalyst showed good catalytic performance for bio-models compound HDO after 5 cycles.

Synergistic contribution of metal–acid sites in selective hydrodeoxygenation of biomass derivatives over Cu/CoOx catalysts

The efficient hydrodeoxygenation (HDO) of biomass derivatives to yield specific products is a significant yet challenging task. In the present study, a Cu/CoOx catalyst was synthesized using a facile co-precipitation method, and subsequently used for the HDO of biomass derivatives. Under optimal reaction conditions, the conversion of 5-hydroxymethylfurfural reached 100% with a selectivity of ∼99% to 2,5-diformylfuran. In combination with the experimental results, systematic characterizations revealed that CoOx, as the acid site, tended to adsorb CO bonds, and the metal sites of Cu+ were inclined to adsorb CO bonds and enhance CO bond hydrogenation. Meanwhile, Cu0 was the main active site for 2-propanol dehydrogenation. The excellent catalytic performance could be attributed to the synergistic effects of Cu and CoOx. Further, by optimizing the ratio of Cu to CoOx, the Cu/CoOx catalysts exhibited notable performance in HDO of acetophenone, levulinic acid, and furfural, which verified the universality of the catalysts in the HDO of biomass derivatives.

Preparation of Ni2P–N/TiO2 Catalyst in N2 Atmosphere and Its Benzofuran Hydrodeoxygenation Performance

Preparation of Ni2P–N/TiO2 Catalyst in N2 Atmosphere and Its Benzofuran Hydrodeoxygenation Performance

Critical role of support crystal structures on highly selective hydrodeoxygenation of lignin-derived vanillin over Pd/ZrO2 catalysts

Hydrodeoxygenation (HDO) of bio-oils obtained by rapid pyrolysis of biomass into high value-added chemicals generally required harsh conditions. Herein, three kinds of mixed-phase ZrO2 supports (denoted as ZSX, X = 2–4) with different crystal structure proportions were prepared by one-pot hydrothermal synthesis method, and their performance on the properties of Pd/ZrO2 catalysts were investigated for vanillin HDO. Pd/ZS3 exhibited excellent efficiency in HDO of vanillin, a typical model compound of lignin, achieving approximately 100% yield of 2-methoxy-4-methylphenol (MMP) in presence of n-butanol as solvent and polymethyl hydrogen siloxane (PMHS) as hydrogen donor under mild conditions (35 °C, 1 h). It was due to catalytic synergy of exposed metal active sites, oxygen vacancies (Ov) and acid sites to occur electron transfer and enhance interaction between Pd and ZrO2. By tuning the crystal structure of ZrO2 support, the influence of Ov and acid sites of Pd/ZrO2 over vanillin HDO performance was investigated, Pd/ZS2 with abundant Ov and Pd/ZS4 with substantial acid sites promoted hydrogenation and hydrogenolysis, respectively, Pd/ZS3 possessed preferable conversion and selectivity as having the properties of both at once. Additionally, reaction pathway was also proposed in which vanillin was converted to MMP by combining intermediate of 4-hydroxy-methyl-2-methoxyphenol (HMP) with active hydrogen species while removing water. This developed catalysts with different crystalline highlighted an enormous promise for HDO of bio-oils into green fuel under mild conditions.

Enhancing catalytic performance of red mud for palmitic acid hydrodeoxygenation by acid pretreatment-induced structural modification

Red mud (RM) is a metal oxide-enriched solid waste material that was subjected to various acid treatments to assess their effect on catalytic performance for hydrodeoxygenation (HDO). Acid pretreatment induces structural changes in RM, which enhances its stability and catalytic performance for HDO. Among the different acid treatments, acetic acid-treated RM catalyst (Ni/RM-HAC) exhibited superior catalytic performance and stability, yielding 81% cetane selectivity and maintaining efficient conversion for up to 400 h. The acetic acid treatment increased the Fe2O3 content in the catalyst, removed inert components such as Na2O and CaO that block pore channels, and greatly improved specific surface area and pore size. Moreover, the acetic acid treatment increased medium acid sites and oxygen vacancy in the catalyst, enhancing its catalytic performance. The increase of Fe3+ makes the catalyst have better stability. These results are expected to aid in the development of efficient, sustainable, and cost-effective catalysts for the production of the second-generation biodiesel.

Hydrodeoxygenation of Pyrolysis Oil in Supercritical Ethanol with Formic Acid as an In Situ Hydrogen Source over NiMoW Catalysts Supported on Different Materials

Hydrodeoxygenation (HDO) is one of the most promising approaches to upgrading pyrolysis oils, but this process normally operates over expensive noble metal catalysts (e.g., Ru/C, Pt/Al2O3) under high-pressure hydrogen gas, which raises processing costs and safety concerns. In this study, a wood-derived pyrolysis oil was upgraded in supercritical ethanol using formic acid as an in situ hydrogen source at 300 °C and 350 °C, over a series of nickel–molybdenum-tungsten (NiMoW) catalysts supported on different materials, including Al2O3, activated carbon, sawdust carbon, and multiwalled nanotubes (MWNTs). The upgrading was also conducted under hydrogen gas (an ex situ hydrogen source) for comparison. The upgrading process was evaluated by oil yield, degree of deoxygenation (DOD), and oil qualities. The NiMoW/MWNT catalyst showed the best HDO performance among all the catalysts tested at 350 °C, with 74.8% and 70.9% of oxygen in the raw pyrolysis oil removed under in situ and ex situ hydrogen source conditions, respectively, which is likely owing to the large pore size and volume of the MWNT support material, while the in situ hydrogen source outperformed the ex situ hydrogen source in terms of upgraded oil yields and qualities, regardless of the catalysts employed.

Catalytic HDO of pyrolysis oil in supercritical ethanol with CoMoP and CoMoW catalysts supported on different carbon materials using formic acid as in-situ hydrogen sources

The work investigated performances of several CoMoP and CoMoW catalysts supported on different carbon materials in catalytic hydrodeoxygenation (HDO) of pyrolysis oil in supercritical ethanol using formic acid as an in-situ hydrogen source. Among them, the CoMoP catalyst supported on ZnCl2 activated sawdust carbon (ASC-Zn) and the CoMoW catalyst supported on multi-walled carbon nanotubes (MWNTs) showed the best HDO performance at both 300 °C and 350 °C for 2 h, obtaining higher upgraded oil yield, lower oxygen contents of the upgraded oils, and higher degrees of deoxygenation (DOD). Whereas the stability tests with three HDO cycles showed that both catalysts were slightly deactivated likely by active metals leach-out or coke/carbon deposition on active sites of the catalysts.

Synergistic effect of acidity and active phases for nickel nanoparticles supported HZSM-5 catalysts on lignin-related model compounds hydrodeoxygenation performance under mild conditions

The cleavage >C-O- bridge bonds and saturate aromatic rings of oxygen compounds from lignin is increasingly important in catalytic hydrodeoxygenation (HDO) for lignin upgrading and value-added utilization. Therefore, the catalytic behavior of a series of HZSM-5 (HZ-5) with different Si/Al ratios (n = 25, 50, 170, and 200) and acidity levels supported Ni nanoparticles (NPs) were prepared by modified deposition-precipitation method for catalytic HDO of lignin-related model compounds (LRMCs). The effects Ni loading, HZ-5 texture, and acid properties on catalytic activity, products distribution, and mechanism were systematically investigated. Furthermore, as-prepared catalysts were characterized by X-ray diffraction, N2 adsorption, scanning electron microscope, energy dispersive spectrometer, pyridine infrared, NH3-temperature programmed desorption, X-ray photoelectron spectrometer, and used for catalytic HDO of LRMCs with different >C-O- bridge bonds and aromatic rings, including oxydibenzene, oxybis(methylene)dibenzene, benzyloxybenzen, and oxydinaphthalene. These results indicate that Ni/HZ-5(n) can activate H2 to biatomic hydrogen (H‧‧‧H) and heterogeneously split H‧‧‧H to relatively mobile H+ and immobile H- with synergistic effect of Ni NPs, further leads to cleave the >Cal-O- and >Car-O- bridge bonds with different conversion through active hydrogen transfer. Additionally, effective modulate of catalytic HDO of LRMCs would be helpful to further maximize the target product yield on the basis of this mechanism at 160 °C for 5 MPa initial hydrogen pressure (mild conditions).

Non-precious metal catalysts supported by activated carbon and TiO2–SiO2: Facile preparation and application for highly effective hydrodeoxygenation of syringol–a lignin-derived model compound

Non-precious metal catalysts (10 wt% loading) over activated carbon (AC) and TiO2–SiO2 supports prepared via incipient wetness impregnation and spray pyrolysis were characterized using various analytical techniques. AC with a higher surface area displayed a better ability than TiO2–SiO2 in syringol conversion and hydrocarbon product selectivity. Compared to Fe and NiFe catalysts, the Ni catalyst showed more effective hydrodeoxygenation performance in terms of syringol conversion, selectivity, and the yield of oxygen-free products (mainly alkylbenzenes via transalkylation reactions). The deoxygenation ability was confirmed via the moisture and COx release. The highest syringol conversion (99.91%) could be obtained using 10 wt% Ni/AC. Generally, syringol hydrodeoxygenation in a fixed-bed reactor followed the main reaction pathway of the hydrogenolysis of CAr–OC(sp3) and CAr–OH rather than the hydrogenation of the benzene ring, producing p-xylene, phenol, and cresols as the major products. Besides metallic catalysts and supports, the reaction temperature and the total flow rate of the H2/Ar mixture on hydrodeoxygenation performance were also investigated. Our study provides a promising potential in the utilization of non-precious metals and biomass-derived AC to remove oxygen from bio-oil model compounds, contributing to the development of sustainable renewable energy.

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.

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.