Aqueous-phase hydrogenolysis of renewable biomass at low H2 pressures is an attractive route to selectively produce renewable fuels and valuable chemicals. Here, we show that Ru and Ni nanoparticles (NPs) dispersed on HZSM-5 with an optimum H• radical transfer catalyzed a rapid rate (152 mmol g–1 h–1) of hydrogenolysis of C–O bonds in lignin-derived guaiacol at 240 °C and 2 bar H2 pressure in water. The coimpregnated individual Ru and Ni nanoparticles (NPs) on HZSM-5 were highly dispersed and did not present an alloy structure, but the individual Ru and Ni NPs were in close proximity. The guaiacol hydrogenolysis rates were proportional to the amounts of the adjacent RuO2 and NiO NPs on the calcined samples, suggesting that the closely contacted Ru and Ni NPs on HZSM-5 are the active sites. In the water phase at low H2 pressures, Ru dissociated the hydrogen molecules to H• radicals (H•), and then such radicals were transferred to adjacent Ni atoms to activate the capability of inert Ni centers. The adjustment of the H• transfer length between Ru and Ni NPs led to shorter H• transfer lengths, which resulted in activities as high as 118 mmol g–1 h–1. The transferring and anchoring of H• radicals was considered to be achieved by the Si–OH groups and their defects on HZSM-5, as demonstrated by a temperature-programmed desorption of hydrogen coupled with mass spectroscopy (TPD/H2-MS) experiment. To further shorten the H• transfer length over uniformly formed Ru and Ni nanoparticles, the isolated Ni islands were removed through the incorporation of a Ru precursor that initially occupied the Brønsted acid sites on HZSM-5. By fully activating the two metals in the aqueous phase via an H• transfer mechanism at low H2 pressures, the rational design of bimetallic Ru–Ni catalysts provides a promising approach for achieving substantially high rates in selective hydrogenolysis steps.Keywords: aqueous-phase hydrogenolysis; bimetallic Ru−Ni; H• radical transfer; lignin; XAFS;

We report a new hydrothermal and basic-additive free process for synthesizing a core(single-crystalline HBEA zeolite)–echinus(nickel phyllosilicate) catalyst, which exhibits excellent reactivity and stability for hydrogenation reactions. Desilication and dealumination processes generate substantial SiO32− ions and exposed Si–OH groups to form nickel phyllosilicate on the external and internal surfaces of zeolite.

Ni based catalysts are wildly used in catalytic industrial processes due to their low costs and high activities. The design of highly hierarchical core–shell structured Ni/HBEA is achieved using a sustainable, simple, and easy-tunable hydrothermal synthesis approach using combined NH4Cl and NH3·H2O as a co-precipitation agent at 120 °C. Starting from a single-crystalline hierarchical H+-exchanged beta polymorph zeolite (HBEA), the adjustment of the precipitate conditions shows that mixed NH4Cl and NH3·H2O precipitates with proper concentrations are vital in the hydrothermal synthesis for preserving a good crystalline morphology of HBEA and generating abundant highly-dispersed Ni nanoparticles (loading: 41 wt%, 5.9 ± 0.7 nm) encapsulated onto/into the support. NH4Cl solution without an alkali is unable to generate abundant Ni nanoparticles from Ni salts under the hydrothermal conditions, whereas NH3·H2O seriously damages the pore structure. After studying the in situ changes in infrared, X-ray diffractometry, temperature-programmed reduction, and scanning electron microscopy measurements, as well as variations in the filtrate pH, Si/Al ratios, and solid sample Ni loading, a two-step dissolution–recrystallization process is proposed. The process consists of Si dissolution and no change in elemental Al, and after the dissolved Si(IV) concentrations have promoted Ni phyllosilicate nanosheet solubility, further growth of multilayered Ni phyllosilicate nanosheets commences. The precursor Ni phyllosilicate is changeable between Ni3Si2O5(OH)4 and Ni3Si4O10(OH)2, because of competition in kinetically-favored and thermodynamically-controlled species caused by different basic agents. The superior catalytic performance is demonstrated in the metal/acid catalyzed biomass derived bulky stearic acid hydrodeoxygenation with 90% octadecane selectivity and a promising rate of 54 g g−1 h−1, which highly excels the reported rates catalyzed by Ni catalysts. Significant improvements in activity and selectivity are related to the highly dispersive Ni nanoparticles onto/into intra-mesopores of hierarchical HBEA, hence enhance the accessibility of bulky substrates to metal sites and mass transfer capacity.

A novel one-pot approach selects a hydrothermally synthesized Cu/SiO2 catalyst (consisting of Cu2O·SiO2 and Cu0 surface species) to catalyze the reduction of a series of fatty esters, fatty acids, and coconut oil to fatty alcohols at 240 °C in methanol without extraneous hydrogen, attaining around 85% conversion and 100% selectivity.

Hydrothermal reduction under aqueous conditions is widely used to convert biomass into more valuable products. However, the harsh conditions inherent in the process can irreversibly alter the intrinsic structure of the support, as well as dissolve the metal ions into the aqueous solution. In this work, for the first time we have synthesized a new highly hydrothermally stable Ru/LaCO3OH catalyst mostly consisting of Ru nanoparticles partially encapsulated by the LaCO3OH support with a strong metal–support interaction (SMSI), which confers high stability and activity to the catalyst under hydrothermal reduction conditions in the hydrogenolysis of the biomass model molecules guaiacol and glycerol. During impregnation, the RuCl3·3H2O precursor initially reacts with LaCO3OH to form a LaRu(CO3)2Cl2 complex and LaOCl. XPS demonstrated that Ru was present in the oxidized state, TEM and XRD showed the absence of Ru0, and the XRD pattern showed the presence of the characteristic lattice fringe of LaOCl. While the LaRu(CO3)2Cl2 complex was resistant to H2 reduction at 350 °C, the complex underwent facile reduction to Ru0 under hydrothermal conditions at 240 °C. In the subsequent process, LaRu(CO3)2Cl2 and LaOCl underwent hydrolysis, forming crystalline LaCO3OH (confirmed by Ag+ titration and XRD patterns), Ru(OH)3, and HCl. The Ru(OH)3 was reduced in situ to Ru0 nanoparticles, as revealed by XPS and TEM analysis. The simultaneous hydrothermal reduction of Run+ species and the formation of crystalline LaCO3OH result in the formation of Ru nanoparticles encapsulated by a protective LaCO3OH layer, as evidenced by HRTEM and DRIFTS CO adsorption measurements. The preparation of catalysts with this unique structure comprising metal nanoparticles protected by the support itself, which confers additional stability, is a novel strategy to prepare hydrothermally stable catalysts.

A tandem process involving the dehydroaromatization of the terpene limonene and the hydrodeoxygenation of stearic acid has been found to be efficiently catalyzed by Pd-Ni/HZSM-5. The process involves the generation of p-cymene from terpene with concomitant formation of H2, which leads to the one-pot hydrodeoxygenation of stearic acid to C17 and C18 alkanes; these products can be used as kerosene additives for aviation fuel. Screening a wide range of catalysts, the bimetallic Pd-Ni/HZSM-5 catalyst is the most efficient, leading to quantitative conversion of stearic acid to alkanes in limonene at 280 °C at a H2 pressure of 2 bar after 120 min. It has been found that single Ni or Pd catalysts lead to a poor conversion of stearic acid in limonene at a H2 pressure of 2 bar. The combination of physically mixed Pd- and Ni-sites onto different supports (Pd/HZSM-5 or Pd/C, and Ni/HZSM-5, Ni/HY, or Ni/HBEA) leads to catalysts which show satisfactory conversion to p-cymene but generally have very low stearic acid conversion rates. Directly incorporating Pd and Ni onto the HZSM-5 scaffold forms the Pd-Ni/HZSM-5 bimetallic catalyst, which demonstrates a remarkable improvement in stearic acid conversion to C17 and C18 alkane products. In this catalyst system, Pd is shown to be the active site for limonene dehydroaromatization, while Ni catalyzes the separate stearic acid hydrodeoxygenation. The acidity of HZSM-5 (modified by the Si/Al ratios) influences the performance of the Pd-Ni bimetallic catalyst, and the proper pore size of HZSM-5 prevents side-reactions from limonene condensation. In addition, the alloyed Pd-Ni nanoparticles (optimized with higher Pd/Ni ratios) on the external surface of HZSM-5 enhance internal H• transfer between the two metals, thereby increasing the rate of stearic acid hydrodeoxygenation. The catalytic compatibility of the Pd and Ni sites, coupled with the proper pore sizes and optimized level of Brönsted acid sites in HZSM-5, result in the design of a multifunctional catalyst that is efficient for both steps of the cascade reaction. Hence, a bimetallic 5%Pd-10%Ni/HZSM-5 catalyst has been developed that allows for a simple approach for producing aromatics and hydrocarbon components present in biojet fuel derived from two biomass resources.Keywords: bimetallic catalysis; cascade reactions; green biofuels; stearic acid HDO; terpene dehydroaromatization

To produce aromatic hydrocarbons from biomass, a novel route is reported for one-pot selective hydrodeoxygenation of a lignin derived aryl ether mixture to C6–C9 aromatic hydrocarbons over Ru/sulfate zirconia in the aqueous phase. The cascade steps undergo the initial precise cleavage of the Caliphatic–O bond of phenolic dimers or Caromatic–OCH3 of phenolic monomers, as well as the full blockage of benzene-ring and cyclic-alkene hydrogenation to realize nearly quantitative aromatic hydrocarbon formation at 240 °C in the presence of low pressurized H2 (2–8 bar). With a Ru catalyst, the primary and competitive steps in hydrogenolysis of the C–O bond and hydrogenation of the benzene ring are shown to be sensitive to temperature and hydrogen pressure, which can subtly modify the concentration and spatial distribution of the surface adsorbed H˙. A high temperature and a low hydrogen pressure are found to be essential for hydrogenolysis, since the H˙ species nearby the oxygen atom are more strongly adsorbed under such conditions and thus preferred to be retained on the Ru surface. Herein it is defined as the “atom-induced H sorption effect”, probably resulting from the analogous hydrogen-bond force between the adsorbed H˙ and the adjacent oxygen atom on the metal surface. Besides the initial step, another key point for aromatic hydrocarbon formation is to optimize the target route of cycloalkene dehydrogenation, but suppress the parallel hydrogenation pathway to saturated cycloalkanes. It is found that the produced phenol intermediate serves as a suitable H-acceptor for the selected catalytic system during the whole conversion, via fast consumption of the in situ produced H˙ from cyclohexene dehydrogenation. Such an interesting phenomenon of internal hydrogen transfer not only promotes the dehydrogenation and hydrogenation equilibrium of cyclohexene but also lowers the in situ H˙ concentration on the Ru surface, both of which would be beneficial for reaching a high benzene yield. This hypothesis for internal hydrogen transfer is further confirmed by separate experiments and density functional theory modelling results.

Hierarchical H-style ultra-stable Y (HUSY) zeolites with abundant interconnected mesopores have been prepared using a sequential post-synthesis strategy that includes steaming dealumination and mixed-alkali desilication. The steaming treatment generates a broad size range of intra-mesopores (around 25 and 45 nm) and a moderate Si/Al ratio of 13.4 in the HUSY, which provides optimal material precursors for the ensuing subsequent alkaline desilication. N2 adsorption–desorption isotherms and X-ray diffractometry results indicate that the sample treated with pyridine/sodium hydroxide (HUSY-4) has a larger external surface area and a higher relative crystallinity. Infrared spectra of adsorbed pyridine show that HUSY-4 contains substantial Brønsted acid sites. The 27Al and 29Si nuclear magnetic resonance spectra show that HUSY-4 possesses few extra-framework alumina species. Infrared spectra in a vacuum show that the peak intensities of HUSY-4 in the bridged hydroxyl group (at 3560 and 3631 cm−1) are much stronger than those of the sample treated with tetrapropylammonium hydroxide (HUSY-3), indicating that the framework integrity of HUSY-4 is better. Differences in treatments with tetrapropylammonium hydroxide/sodium hydroxide and pyridine/sodium hydroxide treatments are attributed to the fact that the pyridine molecule (0.54 nm) can pass through the supercages (0.74 nm) to protect the zeolite framework from deep desilication, whereas the tetrapropylammonium hydroxide molecule (0.85 nm) is adsorbed only on the external surface. Eventually, a HUSY zeolite with a high external surface area, inter-connectedness and hierarchical mesopores (10, 25, and 45 nm) is prepared by initial high-temperature steaming, which is followed by desilication using a mixed alkali solution containing pyridine and sodium hydroxide. High-dispersion (5.5%), high-content (35 wt%), small Ni nanoparticles (4.9 ± 1.2 nm) are loaded onto and into the external surface areas and interpores of the hierarchical HUSY by the deposition–precipitation method. The resultant Ni/HUSY-4 shows an ultra-high efficiency in the hydrodeoxygenation of fatty acids, esters, and palm oil, and achieves high initial rates (60 g g−1 h−1) and a high C18 alkane selectivity (96%), which may be attributed to the enhanced Brønsted acid and adjacent Lewis acid (confirmed by the 1H DQ MAS NMR spectrum) together with the substantial dispersive Ni nanoparticles loaded onto/into the interconnected pores of the hierarchical HUSY support.

The route for selective hydrodeoxygenation of phenethoxybenzene (PEB, which represents the dominant β-O-4 linkage in lignin) to produce benzene and ethylbenzene is realized by employing a multi-functional Ru/sulfate zirconium (Ru/SZ) catalyst in the aqueous phase. One-pot hydrodeoxygenation of PEB is initially cleaved, forming C6 phenol and C8 ethylbenzene via the selective cleavage route of the Caliphatic–O bond (k1). While the C8 ethylbenzene is stable against further hydrogenation under the selected conditions, the C6 phenol intermediate is hydrogenated to cyclohexanol with a rapid rate (k2), and the sequential steps of cyclohexanol dehydration (k3) as well as cyclohexene dehydrogenation (k4) lead to the target benzene formation. A high temperature (240 °C) together with a low hydrogen pressure (8 bar) is essential for achieving such a specific route, suppressing the side-reactions of aromatic hydrogenation. Compared to Ru/SZ, Pd/SZ catalyzes the high rate for cleavage of ether (k1), but fails in sequential C6 phenol hydrogenation (k2) and cyclohexanol dehydration (k3), and thus is not able to accomplish the complex cascade reaction. Pt/SZ performs poorly in the primary step of ether cleavage (k1), and therefore, blocks the following sequential steps. The separate kinetics tests on phenol and cyclohexanol hydrodeoxygenation reveal that benzene is not produced by direct hydrogenolysis, but by the dehydration–dehydrogenation route. The high benzene yield from phenol is probably attributed to few surface adsorbed H˙ species retained on Ru/SZ during phenol hydrodeoxygenation, as evidenced by the model reaction of cyclooctene hydrogenation with the used Ru/SZ in the presence of N2.

A facile and effective method for the one-pot hydrodeoxygenation of enzymatic lignin to C6–C9 cycloalkanes is reported in liquid dodecane with 100 C% selectivity (approaching 50 wt% yield). The method enables 80 wt% lignin conversion by using Ni catalyst-supported amorphous silica-alumina (ASA) at 300 °C in the presence of 6 MPa H2. The crucial factors to achieve direct lignin hydrodeoxygenation are the suitable balance in solvent selection and the design of active sites in the solvent liquid phase. The activity of Ni nanoparticles in dodecane leads to higher efficiency in the deconstruction of external C–O bonds in lignin. The consumption of lignin shifts the equilibrium of lignin solubility and weakens the impact of the relatively poor lignin solubility in dodecane for lignin depolymerization. The key element in controlling the activity of Ni-based catalysts is the specific external surface areas of diverse supports as well as the sizes of metallic Ni sites. This is probably because of the high external surface areas that can provide good contact opportunities for Ni sites in the lignin macromolecule. The efficient contact of active sites in the polymer reactant is the most important factor for such solid–solid reactions. The size and distribution of active Ni sites as well as the specific surface areas of Ni/ASA as modified by the different deposition precipitation times, reduction temperatures, and Ce additives can greatly affect the ability of a metal to attack the external C–O bonds of lignin. Furthermore, the acidity of the support (especially Brönsted acid sites) as modified by the Si/Al ratio of ASA significantly enhances the capabilities and alters the electronic structures of Ni nanoparticles for cleavage of the C–O linkages of lignin. This suggests that the synergy of acid and metal sites can be subtly tailored to strengthen the catalytic performance of Ni metallic sites. In addition, the presence of acidic sites catalyzes the dehydration of cyclic alcohols intermediates and facilitates the hydrodeoxygenation of the derived phenolic fragments to cyclic alkanes.

The mechanisms of dehydroaromatization of limonene to p-cymene are intrinsically investigated over Pd/HZSM-5 under different N2/H2 atmospheres using the mathematical tool of Matlab. It is found that the dehydroaromatization reaction network starts with the isomerization step, and is followed by the sequential dehydrogenation in the presence of N2 or H2 at the selected system. The addition of hydrogen in the atmosphere would not change this reaction pathway, but leads to lower selectivity of p-cymene due to the accelerated hydrogenation rates on the double bonds. Besides, the additional hydrogen speeds up the overall reaction by facilitating the isomerization step on limonene while impeding its reverse reaction, as isomerization of limonene is proved to be the determining step of the whole dehydroaromatization reaction. Furthermore, the presence of hydrogen dramatically decreases the apparent and true activity energy of the target dehydroaromatization reaction and reduces the impact of temperatures to such processes compared to that with a N2 gas carrier.

A highly active catalyst, hierarchical nano-sized Ni/HBEA, is developed for stearic acid and palm oil hydrodeoxygenation (HDO) in dodecane. The TPAOH/NaOH treated hierarchical HBEA sample (crystal size: 15–20 nm) affords more homogeneously dispersed open inter-mesopores (main pore diameter: 25 nm) via controllable base leaching, as evidenced by various microscopy and spectroscopy techniques. By the formation of an aluminum complex on the crystal surface, TPA+ prevents the specific external structure from deep corrosion. After loading Ni nanoclusters, the modified Ni/HBEA was supported with more loadable and dispersive Ni nanoclusters (d = 7.7 ± 1.5 nm) in the newly formed inter-crystalline mesopores, which provide higher accessibility towards heavy molecules, as well as restrict the Ni particle growth. This novel catalyst shows a significantly high initial rate of 67 mmol g−1 h−1 (equivalent to 19 g g−1 h−1) for producing 85% n-C17/C18 and 11% iso-C17/C18 alkanes by stearic acid conversion at 260 °C and 4 MPa H2, and the efficiency of this method is far beyond the current techniques using sulfur-metal and reduced-metal catalysts. The HDO route follows the major pathway of sequential hydrogenation and dehydration steps, affording a highly atom-economical process and a suitable diesel oil ingredient (with certain branched alkanes). In addition, high activities are achieved with the improved catalyst after treatment with high concentration stearic acid in dodecane (up to 0.5 g mL−1), and the catalyst remains highly active and stable in the four recycling runs of palm oil HDO.

The ability to construct supported metal catalysts with high dispersion at high metal loadings is of crucial importance. There are two great challenges to be overcome in order to achieve this goal: the issue of stability of the support material with high surface areas and abundant mesopores at working conditions, and the issue of metal nanoparticles agglomeration upon harsh treatments, especially for transition metals that are difficult to reduce and aggregate easily. To overcome these problems, here we propose a new and promising strategy for encapsulating the Ni nanoclusters (d = 5.6 nm) into/onto the uniform and inter-connected intra-mesopores (7–8 nm) of single-crystalline HBEA, achieving highly dispersive Ni nanoparticles (content: 40 wt%, dispersion: 3.5%) on the stable carrier. The architecture of relative position of the Ni nanoparticles and support is directly revealed by ultrathin sections transmission electron microscopy and N2 sorption measurements, presented together with the indirect evidences of temperature programmed reduction of H2 and IR spectroscopy of adsorbed CO. In comparison to such an advantageous structure of metal and support, the Ni nanoparticles are more commonly deposited on the limited external surface or inter-mesopores of commercial HBEA carriers. Besides, the novel catalyst shows superior adsorption performance towards large molecules. As expected, the catalyst leads to a significantly high initial rate of 132 mmol g−1 h−1 (equivalent to 38 g g−1 h−1) and highly selective octadecane formation (96% yield) from stearic acid conversion. Consequently, high activity and stable durability are realized for four recycling runs of drainage oil hydrodeoxygenation with the newly developed Ni/HBEA.

The cleavage of C–O bonds in phenol, catechol, and guaiacol has been explored with mono- and dual-functional catalysts containing Ni and/or HZSM-5 in the aqueous phase. The aromatic ring of phenol is hydrogenated in the first step, and the C–O bond of the resulting cyclohexanol is dehydrated in sequence. The initial turnover frequency (TOF) of phenol hydrodeoxygenation increases in parallel with the acid site concentration irrespective of the concentration of the accessible surface Ni atoms. For catechol and guaiacol conversion, Ni catalyzes the hydrogenolysis of the C–O bonds in addition to arene hydrogenation. For catechol, the hydrogenation of the aromatic ring and the hydrogenolysis of the phenolic –OH group occur in parallel with a ratio of 8:1. The saturated cyclohexane-1,2-diol can be further dehydrated over HZSM-5 or hydrogenolyzed on Ni to complete hydrodeoxygenation. Guaiacol undergoes primarily hydrogenolysis (75%) to phenol via demethoxylation, and the hydrogenation route accounts for only 25%. This is attributed to the steric effects arising from the adjacent sp3 hybrid O–CH3 group. 2-Methoxycyclohexanol (from guaiacol hydrogenation) reacts further either via hydrogenolysis by Ni to cyclohexanol or via acid catalyzed demethoxylation and rearrangement steps followed by the subsequent hydrogenation of the intermediately formed olefins. On Ni/HZSM-5, the hydrodeoxygenation activities are much higher for the phenolic monomers than for their respective saturated analogues, pointing to the importance of sp2 orbitals. The presence of proximal acid sites increases the activities of Ni in the presence of H2 by a synergistic action.

The utilization of lignin as a fuel precursor has attracted attention, and a novel and facile process has been developed for one-pot conversion of lignin into cycloalkanes and alkanes with Ni catalysts under moderate conditions. This cascade hydrodeoxygenation approach may open the route to a new promising technique for direct liquefaction of lignin to hydrocarbons.

The traditional methodology includes a carbon-chain shortening strategy to produce bio-jet fuel from lipids via a two-stage process with hydrogen. Here, we propose a new solution using a carbon-chain filling strategy to convert C10 terpene and lipids to jet fuel ranged hydrocarbons with aromatic hydrocarbon ingredients in the absence of hydrogen.

Hierarchically porous zeolite supported metal nanoparticles are successfully prepared through a base-assisted chemoselective interaction between the silicon species on the zeolite crystal surface and metal salts, in which in situ construction of mesopores and high dispersion of metal species are realized simultaneously.

A novel one-pot approach selects a hydrothermally synthesized Cu/SiO2 catalyst (consisting of Cu2O·SiO2 and Cu0 surface species) to catalyze the reduction of a series of fatty esters, fatty acids, and coconut oil to fatty alcohols at 240 °C in methanol without extraneous hydrogen, attaining around 85% conversion and 100% selectivity.

Hierarchical H-style ultra-stable Y (HUSY) zeolites with abundant interconnected mesopores have been prepared using a sequential post-synthesis strategy that includes steaming dealumination and mixed-alkali desilication. The steaming treatment generates a broad size range of intra-mesopores (around 25 and 45 nm) and a moderate Si/Al ratio of 13.4 in the HUSY, which provides optimal material precursors for the ensuing subsequent alkaline desilication. N2 adsorption–desorption isotherms and X-ray diffractometry results indicate that the sample treated with pyridine/sodium hydroxide (HUSY-4) has a larger external surface area and a higher relative crystallinity. Infrared spectra of adsorbed pyridine show that HUSY-4 contains substantial Brønsted acid sites. The 27Al and 29Si nuclear magnetic resonance spectra show that HUSY-4 possesses few extra-framework alumina species. Infrared spectra in a vacuum show that the peak intensities of HUSY-4 in the bridged hydroxyl group (at 3560 and 3631 cm−1) are much stronger than those of the sample treated with tetrapropylammonium hydroxide (HUSY-3), indicating that the framework integrity of HUSY-4 is better. Differences in treatments with tetrapropylammonium hydroxide/sodium hydroxide and pyridine/sodium hydroxide treatments are attributed to the fact that the pyridine molecule (0.54 nm) can pass through the supercages (0.74 nm) to protect the zeolite framework from deep desilication, whereas the tetrapropylammonium hydroxide molecule (0.85 nm) is adsorbed only on the external surface. Eventually, a HUSY zeolite with a high external surface area, inter-connectedness and hierarchical mesopores (10, 25, and 45 nm) is prepared by initial high-temperature steaming, which is followed by desilication using a mixed alkali solution containing pyridine and sodium hydroxide. High-dispersion (5.5%), high-content (35 wt%), small Ni nanoparticles (4.9 ± 1.2 nm) are loaded onto and into the external surface areas and interpores of the hierarchical HUSY by the deposition–precipitation method. The resultant Ni/HUSY-4 shows an ultra-high efficiency in the hydrodeoxygenation of fatty acids, esters, and palm oil, and achieves high initial rates (60 g g−1 h−1) and a high C18 alkane selectivity (96%), which may be attributed to the enhanced Brønsted acid and adjacent Lewis acid (confirmed by the 1H DQ MAS NMR spectrum) together with the substantial dispersive Ni nanoparticles loaded onto/into the interconnected pores of the hierarchical HUSY support.

Hierarchically porous zeolite supported metal nanoparticles are successfully prepared through a base-assisted chemoselective interaction between the silicon species on the zeolite crystal surface and metal salts, in which in situ construction of mesopores and high dispersion of metal species are realized simultaneously.

The route for selective hydrodeoxygenation of phenethoxybenzene (PEB, which represents the dominant β-O-4 linkage in lignin) to produce benzene and ethylbenzene is realized by employing a multi-functional Ru/sulfate zirconium (Ru/SZ) catalyst in the aqueous phase. One-pot hydrodeoxygenation of PEB is initially cleaved, forming C6 phenol and C8 ethylbenzene via the selective cleavage route of the Caliphatic–O bond (k1). While the C8 ethylbenzene is stable against further hydrogenation under the selected conditions, the C6 phenol intermediate is hydrogenated to cyclohexanol with a rapid rate (k2), and the sequential steps of cyclohexanol dehydration (k3) as well as cyclohexene dehydrogenation (k4) lead to the target benzene formation. A high temperature (240 °C) together with a low hydrogen pressure (8 bar) is essential for achieving such a specific route, suppressing the side-reactions of aromatic hydrogenation. Compared to Ru/SZ, Pd/SZ catalyzes the high rate for cleavage of ether (k1), but fails in sequential C6 phenol hydrogenation (k2) and cyclohexanol dehydration (k3), and thus is not able to accomplish the complex cascade reaction. Pt/SZ performs poorly in the primary step of ether cleavage (k1), and therefore, blocks the following sequential steps. The separate kinetics tests on phenol and cyclohexanol hydrodeoxygenation reveal that benzene is not produced by direct hydrogenolysis, but by the dehydration–dehydrogenation route. The high benzene yield from phenol is probably attributed to few surface adsorbed H˙ species retained on Ru/SZ during phenol hydrodeoxygenation, as evidenced by the model reaction of cyclooctene hydrogenation with the used Ru/SZ in the presence of N2.

The utilization of lignin as a fuel precursor has attracted attention, and a novel and facile process has been developed for one-pot conversion of lignin into cycloalkanes and alkanes with Ni catalysts under moderate conditions. This cascade hydrodeoxygenation approach may open the route to a new promising technique for direct liquefaction of lignin to hydrocarbons.

The traditional methodology includes a carbon-chain shortening strategy to produce bio-jet fuel from lipids via a two-stage process with hydrogen. Here, we propose a new solution using a carbon-chain filling strategy to convert C10 terpene and lipids to jet fuel ranged hydrocarbons with aromatic hydrocarbon ingredients in the absence of hydrogen.