A route was developed for the synthesis of diesel and jet fuel range C9 and C10 alkanes with furfural and angelica lactone, which can be obtained from hemicellulose and cellulose. It was found that angelica lactone is more reactive than levulinic acid or its other derivates in the aldol condensation with furfural. Among the investigated catalysts, Mn2O3 was found to be the most active and was very stable for the aldol condensation of furfural and angelica lactone. Over Mn2O3, a high carbon yield of C10 oxygenates (about 96%) can be achieved by the aldol condensation of furfural and angelica lactone under mild conditions (353 K, 4 h). By the hydrogenation and hydrodeoxygenation of the aldol condensation product over the Pd/C and Pd-FeOx/SiO2 catalysts, high carbon yields (∼96%) of C9 and C10 alkanes were obtained.Keywords: aldol condensation; angelica lactone; diesel and jet fuels; hydrodeoxygenation; lignocellulose;

High-density (0.82 g mL–1) jet-fuel range cycloalkanes were synthesized in high overall yields (∼80%) by the aldol condensation of cyclopentanone and butanal followed by hydrodeoxygenation (HDO). Among the investigated solid-base catalysts, magnesium–aluminum hydrotalcite (MgAl-HT) exhibited the highest activity for the solvent-free aldol condensation of cyclopentanone and butanal. The excellent performance of MgAl-HT was rationalized by the synergism between strong base and weak acid sites on the surface of this material. The aldol condensation products were further hydrodeoxygenated to butylcyclopentane and 1,3-dibutylcyclopentane over the Ni/SiO2, Pd/SiO2, and bimetallic Ni–Pd/SiO2 catalysts. Compared to the Ni/SiO2 and Pd/SiO2 catalysts, the bimetallic Ni–Pd/SiO2 catalyst exhibited higher activity for the solvent-free HDO reaction. Over the 4%Ni–1%Pd/SiO2 catalyst, high carbon yield (88.0%) of butylcyclopentane and 1,3-dibutylcyclopentane was achieved at 503 K. According to the characterization results, the excellent performance of Ni–Pd/SiO2 catalyst can be explained by the formation of Ni–Pd alloy.

The selective dehydration of pinacol derivatives to branched 1,3-dienes is extremely challenging because of the predominance of pinacol rearrangement. Herein, we successfully achieve this goal by employing a recyclable solid acid/ionic liquid catalyst system. The dehydration of alkyl- and cycloalkyl-derived diols in an Amberlyst-15/[Emim]Cl system afforded the corresponding 1,3-dienes in good yields, while a Nafion/[Emim]Cl system was demonstrated to be a better catalyst system for the dehydration of aryl-substituted substrates. Our protocol features straightforward and simple access to branched 1,3-dienes, high chemoselectivity, a recyclable catalyst system, a facile separation of dienes just by decantation, and a broad substrate scope.Keywords: Amberlyst-15; branched 1,3-dienes; ionic liquid; Nafion; pinacol dehydration; solid acid; [Emim]Cl;

Herein, we report an unprecedented and sustainable route to synthesize pyromellitic acid (PMA), a monomer of polyimide, with pinacol and diethyl maleate which can be derived from lignocellulose. Analogously, a sustainable route to trimellitic acid (TMA) was also developed using pinacol and acrylate as the feedstocks.

•Jet fuel range C9 cycloalkane was first synthesized by the HDO of isophorone.•Glycerol was first used as a renewable hydrogen resource for the HDO process.•Pt/Al2O3 was highly effective for the coupling of APR and HDO reactions.•Other lignocellulosic polylols can also be used as the hydrogen resources.•C9 cycloalkane as obtained can be used as an additive to conventional bio-jet fuel.For the first time, 1,​1,​3-​trimethyl-cyclohexane (a jet fuel range cycloalkane) was synthesized by coupling the aqueous phase reforming (APR) of glycerol and the hydrodeoxygenation (HDO) of isophorone which can be obtained from lignocellulose. Among the investigated catalysts, Pt/Al2O3 was found to be the most active for the production of 1,​1,​3-​trimethyl-cyclohexane with the hydrogen which was in-situ generated by the APR of glycerol. Over it, high carbon yield (67.0%) of 1,​1,​3-​trimethyl-cyclohexane can be achieved at 533 K in the absence of external hydrogen. The excellent performance of Pt/Al2O3 catalyst can be explained because Pt is highly active for both APR and HDO reactions. Besides glycerol, many other lignocellulose derived polylols (such as ethylene glycol, xylitol and sorbitol) and methanol can also be used as renewable hydrogen source for the HDO of isophorone. As a potential application, the 1,​1,​3-​trimethyl-cyclohexane as obtained can be blended into the conventional jet fuels to improve their volumetric heat values.Download high-res image (161KB)Download full-size image

For the first time, a renewable acidic resin which was prepared by one-step condensation/sulfation of sodium sulfite, cyclopentanone and formaldehyde followed by ion-exchanging was found to be a highly active and stable catalyst for the production of 5-hydroxymethylfurfural (HMF) by the dehydration of fructose and inulin.

•Pd-FeOx/SiO2 catalyst was found to be highly active for the HDO of furan compounds.•The presence of iron species restrains the CC cleavage over the Pd/SiO2 catalyst.•The presence of FeOx decreases the hydrogen pressure requirement for HDO process.•The synergism effect of Pd and Fe species leads to the high activity of catalyst.For the first time, the Pd/SiO2 which was modified by FeOx species (Pd-FeOx/SiO2) was reported as an active catalyst for the solvent-free hydrodeoxygenation (HDO) of the aldol condensation product of furfural and methyl-isobutylketone (MIBK). The presence of iron species not only restrains the CC cleavage (decarbonylation and retro-aldol condensation) over the Pd/SiO2 catalyst but also decreases the hydrogen pressure which is needed for the total HDO of aldol condensation product over the Pd/SiO2 catalyst. Compared with the Pd/SiO2 catalyst, the Pd-FeOx/SiO2 catalyst also exhibited higher activity for the HDO of other furan compounds under atmospheric pressure. Over the 5%Pd-2.5%FeOx/SiO2 catalyst, complete conversion of feedstocks and high carbon yields of jet fuel range alkanes (87–94%) can be achieved by the atmospheric HDO of a series of furan compounds at 623 K or 573 K. From the results of XRD, STEM, CO chemisorption, FT-IR, EXAFS, H2-TPR, in-situ XPS and quasi-in-situ Mössbauer spectra, it was noticed that the modification of iron species decreases the coordination number of Pd–Pd on the Pd/SiO2 catalyst, which may restrain the decarbonylation during the HDO process. The presence of Pd promotes the reduction of iron species and the generation of Pd-Fe alloy. Both effects may be the reasons why the Pd-FeOx/SiO2 catalyst is more active than Pd/SiO2 in the solvent-free HDO of furan compounds under atmospheric pressure.Download high-res image (230KB)Download full-size image

AbstractA series of renewable C9–C12 triketones with repeating [COCH2CH2] units were synthesized in high carbon yields (ca. 90 %) by the aqueous-phase hydrogenation of the aldol-condensation products of 5-hydroxylmethylfurfural (HMF) and ketones over an Au/TiO2 catalyst. Compared with the reported routes, this new route has many advantages such as being environmentally friendly, having fewer steps, using a cheaper and reusable catalyst, etc. The triketones as obtained can be used as feedstocks in the production of conducting or semi-conducting polymers. Through a solvent-free intramolecular aldol condensation over solid-base catalysts, the triketones were selectively converted to diketones, which can be used as intermediates in the synthesis of useful chemicals or polymers. As another application, the tri- and diketones can also be utilized as precursors for the synthesis of jet-fuel range branched cycloalkanes with low freezing points (224–248 K) and high densities (ca. 0.81 g mL−1).

1-(3-Cyclopentyl)cyclopentyl-2-cyclopentylcyclopentane, a renewable high-density fuel, was first produced in a high overall carbon yield (∼70%) with cyclopenanone that can be derived from hemicellulose. The synthetic route used in this work contains three steps. In the first step, 2-cyclopentyl cyclopentanone was synthesized for the first time by a one-pot reaction of cyclopentanone and hydrogen under the catalysis of Raney metal and alkali hydroxides. Over the optimized catalyst (Raney cobalt + KOH), a high carbon yield (83.3%) of 2-cyclopentyl cyclopentanone was achieved at 353 K. In the second step, 2-cyclopentyl-5-(2-cyclopentylcyclopentylidene)cyclopentanone was produced in a high carbon yield (95.4%) by the solvent-free self-aldol condensation of 2-cyclopentyl cyclopentanone under the vacuum conditions. In the third step, the 2-cyclopentyl-5-(2-cyclopentylcyclopentylidene)cyclopentanone was hydrodeoxygenated over the Ni-SiO2 catalyst under solvent-free conditions. High carbon yields of 1-(3-cyclopentyl)cyclopentyl-2-cyclopentylcyclopentane (88.5%) and polycycloalkanes (99.0%) were obtained. The Ni-SiO2 catalyst was stable under investigated conditions. No evident deactivation was noticed during the 50 h time on stream. The as-obtained polycycloalkane mixture has a density of 0.943 g mL–1 and a freezing point of 233.7 K. As a potential application, it can be blended into conventional high density fuels (e.g., JP-10) for rockets and missile propulsion.Keywords: Aldol condensation; Cyclopentanone; High density fuel; Hydrodeoxygenation; Lignocellulose; Selective hydrogenation;

A new route for the selective synthesis of renewable 1,3-cyclopentanediol was developed by the aqueous phase rearrangement of furfuryl alcohol to 4-hydroxycyclopent-2-enone followed by hydrogenation. The presence of a small amount of base catalysts is beneficial for the aqueous phase rearrangement of furfuryl alcohol to 4-hydroxycyclopent-2-enone. Such a promotion effect of base catalysts can be rationalized by restraining the generation of levulinic acid which may catalyze the polymerization of furfuryl alcohol. In the hydrogenation of 4-hydroxycyclopent-2-enone to 1,3-cyclopentanediol, an evident solvent effect was noticed. Higher carbon yields of 1,3-cyclopentanediol were obtained when tetrahydrofuran was used as the solvent. In the large scale tests with high initial concentrations of feedstocks, a high overall carbon yield (72.0%) of 1,3-cyclopentanediol was achieved over cheap catalysts (MgAl-HT and RANEY® Ni). As a potential application, 1,3-cyclopentanediol as obtained was successfully used as a monomer in the synthesis of polyurethane.

Diesel and jet fuel range branched alkanes were first synthesized by the combination of hydroxyalkylation/alkylation (HAA) of 2-methylfuran with angelica lactone and subsequent hydrodeoxygenation. Compared with the previous ethyl levulinate route, the angelica lactone route exhibited evident advantages at higher HAA reactivity.

For the first time, gasoline and diesel range C6–C15 branched alkanes were directly synthesized in a high carbon yield (∼80%) by the self-condensation of acetone and subsequent hydrodeoxygenation over a dual-bed catalyst system.

Decalin is the main component of JP-900, a thermally stable and high-energy density jet fuel. Decalin is also an important component of advanced jet fuels. Cyclopentanol is a platform compound that can be derived from lignocellulose. In this work, a mixture of C10 and C15 polycycloalkanes (with decalin as the major component) was first synthesized by the oligomerization/rearrangement of cyclopentene from the dehydration of cyclopentanol, followed by hydrogenation. Among the investigated catalysts, Amberlyst-36 resin demonstrated the highest activity and excellent stability for cyclopentanol dehydration and cyclopentene oligomerization/rearrangement. The influences of reaction temperature and reaction time on the catalytic performances of Amberlyst-36 resin for both reactions were investigated. Under the optimum conditions, 84.0% carbon yield of cyclopentene was obtained from cyclopentanol dehydration, and 74.2% carbon yield of C10 and C15 polycycloalkenes was achieved by the oligomerization/rearrangement of cyclopentene. Finally, the C10 and C15 polycycloalkenes from the oligomerization/rearrangement of cyclopentene were further hydrogenated to a mixture of C10 and C15 polycycloalkanes with decalin as the major component (77% selectivity). This polycycloalkane mixture has high density (0.896 g mL–1). As a potential application, it can be used as an additive to improve the volumetric calorific values of conventional biojet fuels.Keywords: Cyclopentanol; Dehydration; Jet fuel; Lignocellulose; Oligomerization/rearrangement; Solid acid catalyst

Protonated phenol-formaldehyde condensation products of sodium lignosulfonate and lignocellulose derived aldehydes were first reported as cost-effective catalysts for the hydroxyalkylation/alkylation (HAA) of 2-methylfuran and furfural. Among them, the LF resin which was prepared with sodium lignosulfonate and formaldehyde exhibited the best performance. With the LF resin, higher activity, catalytic efficiency and stability than those of Amberlyst resins were observed, which can be rationalized by its higher acidic strength. The HAA product of 2-methylfuran and furfural was further converted to diesel and jet fuel range alkanes by the solvent-free hydrodeoxygenation (HDO) over the Ni/H-ZSM-5 catalysts prepared by conventional or complexation impregnation methods. It was found that the presence of complex agents can promote the dispersion of Ni, which leads to the higher HDO activity of Ni/H-ZSM-5 catalysts.

For the first time, jet fuel range C8–C9 aromatic hydrocarbons were synthesized in high carbon yield (∼80%) by the catalytic conversion of isophorone over MoOx/SiO2 at atmospheric pressure. A possible reaction pathway was proposed according to the control experiments and the intermediates generated during the reaction.

Diesel range branched alkanes were synthesized by the solvent-free hydrodeoxygenation of 5,5′-(butane-1,1-diyl)bis(2-methylfuran), the hydroxyalkylation/alkylation product of 2-methylfuran and butanal. Over the non-noble metal catalyst Ni/Hβ-(394), ∼90% carbon yield of diesel range alkanes was achieved at a much lower temperature (503 K) than the temperature (623 K) used in the literature over noble metal catalysts.

Under solvent-free conditions, C9–C12 alkanes were first synthesized at high overall carbon yield (∼80%) by the solid base catalyzed aldol condensation of furfural with 2-pentanone (or a mixture of 2-pentanone and 2-heptanone) from lignocellulose, followed by direct hydrodeoxygenation over Pd loaded solid acid catalysts at 533 K.

By the combination of solvent-free aldol condensation and one-step hydrodeoxygenation under mild reaction conditions, a high-density (0.866 g mL−1) bicyclic C10 hydrocarbon was synthesized in high overall yield (up to 80%) using cyclopentanone derived from lignocellulose.

For the first time, Mo modified Rh/SiO2 was found to be an effective catalyst for the aqueous phase selective hydrogenation of levulinic acid to 1,4-pentanediol. Over such a catalyst, high levulinic acid conversion (100%) and 1,4-pentanediol yield (70%) can be achieved at low temperature (353 K).

A new strategy for the synthesis of jet fuel range branched alkanes with the xylose and methyl isobutyl ketone (MIBK) from lignocellulose was introduced. C10 and C11 branched alkanes with low freezing points were synthesized by three steps: (1) the dehydration of xylose to furfural over solid acid catalysts in MIBK/water biphasic solvent systems; (2) solid base catalyzed aldol condensation of furfural with MIBK which was also the most effective extracting solvent in the first step; (3) solvent-free hydrodeoxygenation of aldol condensation product to jet fuel range branched alkanes over Ru/H-ZSM-5 catalyst. Alternatively, oxygenated fuel can also be obtained by the low temperature hydrogenation of aldol condensation product over Ru/C catalyst.

2-Methylfuran (2-MF) and cyclopentanone (CPO) are the selective hydrogenation products of furfural, which can be produced in industrial scale with lignocellulose. In this work, renewable diesel or jet fuel range branched alkanes and cycloalkanes were first synthesized simultaneously by the solvent-free hydroxyalkylation/alkylation (HAA) of 2-MF and CPO followed by hydrodeoxygenation (HDO). Among the solid acid catalysts used in this work, Nafion-212 resin exhibited the best activity and selectivity for the HAA of 2-MF and CPO. The excellent performance of Nafion-212 resin can be attributed to the high acid strength of this catalyst. After the HDO of the HAA products of 2-MF and CPO over several nickel catalysts, a mixture of jet fuel range branched alkanes and cycloalkanes with relatively higher density was obtained at high carbon yield. Compared with Ni/SiO2, acidic support loaded nickel catalysts are more active in the HDO process, which may be attributed to the promotion effect of acid sites in dehydration and the ring opening reaction of furan compounds.

•La1−xSrxFe1−yMnyO3 hollow nanospheres were synthesized by a solvothermal method.•With the help of urea, the nucleation temperature was greatly reduced to 100 °C.•The obtained hollow spheres have smaller diameters and larger surface areas.•La1−xSrxFe1−yMnyO3 catalysts show superior activity for the decomposition of H2O2.•No leaching was observed due to the perovskite structure of catalysts.Perovskite-type LaFeO3 and La1−xSrxFe1−yMnyO3 hollow nanospheres were prepared, for the first time, via a urea-assisted one-pot solvothermal method. The chemical compositions, crystalline phases, specific surface areas and morphologies of the materials as-prepared were characterized by ICP-OES, XRD, nitrogen adsorption and TEM, respectively. It was found that the presence of urea greatly decreased the nucleation temperature which led to the smaller particle sizes of products. As a potential application, the materials as-prepared exhibited superior activity and good stability in the catalytic decomposition of hydrogen peroxide. The excellent activity of La1−xSrxFe1−yMnyO3 hollow nanospheres can be rationalized by their high specific surface areas and hollow nanoparticle morphology. The high stability of these materials can be attributed to their perovskite-type crystal structures.

Phosphoric acid treated niobic acid (NbP) was used for the dehydration of xylose to furfural in biphasic solvent system, which was found to exhibit the best performance among the tested catalysts. The excellent performance of NbP could be explained by the better synergistic cooperation between Brönsted and Lewis acid sites. Moreover, NbP showed good stability and no obvious deactivation or leaching of Nb could be observed after six continuous recycles.NbP is a very effective and stable catalyst for the dehydration of xylose to furfural in the toluene/water biphasic system. The better cooperation of Brönsted and Lewis acid sites is responsible for its excellent performance.Download full-size image

In this work, MoOx promoted Ir/SiO2 catalysts were prepared and used for the selective hydrogenolysis of tetrahydrofurfuryl alcohol (THFA) to 1,5-pentanediol in a continuous flow reactor. The effects of different noble metals (Ir, Pt, Pd, Ru, Rh), supports and Ir contents were screened. Among the investigated catalysts, 4 wt%Ir-MoOx/SiO2 with a Mo/Ir atomic ratio of 0.13 exhibited the best catalytic performance. The synergy between Ir particles and the partially reduced isolated MoOx species attached on them is essential for the excellent catalytic performance of Ir-MoOx/SiO2. The catalyst exhibited a better hydrogenolysis efficiency of THFA with the selectivity of 1,5-pentanediol of 65%–74% at a conversion of THFA of 70%–75% when the initial THFA concentration is ranging from 20 wt% and 40 wt%. And higher system pressure was also in favor of the conversion of THFA. During a stability test, the conversion of THFA and 1,5-pentanediol yield over Ir-MoOx/SiO2 decreased with reaction time, which can be explained by the leaching of Mo species during the reaction.In this work, Mo modified Ir/SiO2 (Ir-MoOx/SiO2) catalyst was used for the selective hydrogenolysis of tetrahydrofurfuryl alcohol to 1,5-pentanediol in continuous flow reactor and exhibited high activity and selectivity even under mild conditions.Download full-size image

For the first time, jet fuel range C8–C9 aromatic hydrocarbons were synthesized in high carbon yield (∼80%) by the catalytic conversion of isophorone over MoOx/SiO2 at atmospheric pressure. A possible reaction pathway was proposed according to the control experiments and the intermediates generated during the reaction.

By the combination of solvent-free aldol condensation and one-step hydrodeoxygenation under mild reaction conditions, a high-density (0.866 g mL−1) bicyclic C10 hydrocarbon was synthesized in high overall yield (up to 80%) using cyclopentanone derived from lignocellulose.

For the first time, Mo modified Rh/SiO2 was found to be an effective catalyst for the aqueous phase selective hydrogenation of levulinic acid to 1,4-pentanediol. Over such a catalyst, high levulinic acid conversion (100%) and 1,4-pentanediol yield (70%) can be achieved at low temperature (353 K).