Highly efficient hydrogenation of levulinic acid into γ-valerolactone over modified bifunctional yolk-shell catalyst.

Hydrogenation of levulinic acid to gamma-valerolactone over nickel supported organoclay catalyst

γ-Valerolactone (GVL) is receiving increasing attention because of its significant characteristics of an ideal sustainable liquid fuel. In this work, a novel and nonprecious metal catalytic method of the hydrogenation of biomass-derived levulinic acid (LA) into GVL by water splitting is first reported. Commercially available nonprecious metals of Fe, Ni, Cu, Cr, and Mo exhibited significantly catalytic activities in the hydrogenation of LA into GVL. Over 90% yield of GVL from LA can be obtained at a relatively low temperature of 180 °C, and an excellent 98% yield of GVL was achieved over the Fe catalyst at 250 °C. Catalyst Fe is stable and still keeps the high catalytic activity after recycles. The extraordinary catalytic activity of the general Fe powder is probably because of the role of hot water and also a synergistic role of the Fe and ZnO or Zn/ZnO. Also, the reactor wall of a reactor made of the stainless steel material acted as a significant catalyst, and a considerably high GVL yield of 56% can b...

Synergistic Ru[sbnd]Co atomic pair with enhanced activity toward levulinic acid hydrogenation

Clean and efficient conversion of renewable levulinic acid to levulinate esters catalyzed by an organic-salt of H4SiW12O40

Highly selective production of value-added γ-valerolactone from biomass-derived levulinic acid using the robust Pd nanoparticles

Direct cascade hydrogenation of biorenewable levulinic acid to valeric acid biofuel additives over metal (M = Nb, Ti, and Zr) supported SBA-15 catalysts

The hydrogenation of levulinic acid (LA) to γ-valerolactone (GVL) in vapor-phase is economically more viable route if compared to reaction in liquid-phase. To improve the GVL yield in the vapor-phase reaction, the optimization of nickel modified zeolite as bi-functional catalyst (Ni/HZSM-5) was studied. Ni/HZSM-5 materials with fixed Al/Si molar ratio of 0.04 and different nominal Ni/Si molar ratios (from 0.01 to 0.05) were synthesized without the use of organic template and with the most affordable sources of silica and alumina. Materials were characterized by X-ray powder diffraction, SEM-EDX, TEM-EDX, pyridine TPD and DRIFTS, H2-TPR, N2 physisorption and isoelectric point. In the synthesized materials, 61–83% of nickel is present as bulk NiO and increases with nickel content. Additionally, in all catalysts, a small fraction of Ni2+ which strongly interacts with the zeolite support was detected (10–18%), as well as Ni2+ acting as charge compensating cations for Brønsted acid sites (7–21%). Increasing the nickel content in the catalysts leads to a progressive decrease of Brønsted acid sites (BAS) and concomitant increase of Lewis acid sites (LAS). When BAS/LAS is approaching to 1 and at the same time the amount of NiO reducible active sites is around 80%, the bi-functional Ni/HZSM-5-3 catalyst (Ni/Al = 0.59) leads to 99% conversion of LA and 100% selectivity to GVL at 320°C. This catalyst also shows stable levulinic acid hydrogenation to GVL in 3 reaction cycles conducted at 320°C. The concerted action of the following active sites in the catalyst is a key element for its optimized performance: (1) Ni metallic active sites with hydrogenation effect, (2) Lewis acid sites with dehydration effect, and (3) nickel aluminate sites with synergetic and stabilizing effects of all active sites in the catalyst.

Microwave-enhanced catalytic transfer hydrogenation of levulinic acid to γ-valerolactone using zirconium-based metal organic frameworks: A comparative study with conventional heating processes

Different loading of palladium (Pd) nanoparticles were successfully fabricated on multi-walled carbon nanotubes using Pd acetylacetonate as the precursor via a simple liquid impregnation method. The crystal phase, morphology, textural structure and the chemical state of the resulting Pd nanoparticles (Pd/CNT) catalysts were studied and the characterization results indicated that the uniform dispersion of small Pd nanoparticles with the size range of 1.0–4.5 nm was achieved. The synthesized Pd/CNT catalysts exhibited efficient performance for the catalytic hydrogenation of biomass-derived levulinic acid into biofuel γ-valerolactone. In comparison with the commercial 5 wt% Pd/C and the 5 wt% Pd/CNT catalyst prepared by Pd nitrate precursor, much higher activities were achieved, whereas the biofuel γ-valerolactone was highly produced with 56.3 % yield at 57.6 % conversion of levulinic acid on the 5 wt% Pd/CNT catalyst under mild conditions. The catalyst developed in this work may be a good candidate for the wide applications in the hydrogenation.

The new catalyst Pd@mSiO2 was synthesized by a simple and gentle one-step process, mesoporous silica as the shell and metal particles as the core. The characterization showed that the catalyst structure was regular, the core–shell structure was clear, and each microsphere guarantees the existence of a single nucleus. The pore size and the thickness of mesoporous silica layer can be effectively adjusted by adjusting the molecular weight of template and the amount of silicon source. The Pd@mSiO2 was applied in the hydrogenation of levulinic acid to prepare γ-valerolactone, the conversion of levulinic acid was 95%, and the selectivity of γ-valerolactone was close to 96%. In addition, the catalyst had a good reuse performance compared to commercial catalysts. After repeated use for ten times, the catalytic activity did not decrease, which was mainly attributed to the fact that the core–shell structure can better protect the active metal particles and prevent the particles from agglomeration and loss at high temperature.

Hydrogenation of levulinic acid (LA) was investigated with several commercial catalysts for the production of γ-valerolactone (GVL). In contrast with other catalysts, Raney Ni prepared from melt-quenching alloy (RQ-Ni) performed the best activity and selectivity. Under the optimal reaction conditions of 373 K and 1.5 MPa for 4 h, 99.3 % conversion of LA and 98.1 % selectivity of GVL were obtained with isopropanol solvent. RQ-Ni with low cost offered a better alternative than noble metal catalysts and it also was more stable than commercial Raney Ni catalyst.

Stable yolk-structured catalysts towards aqueous levulinic acid hydrogenation within a single Ru nanoparticle anchored inside the mesoporous shell of hollow carbon spheres

Catalytic hydrogenation of levulinic acid to γ-valerolactone over lignin-metal coordinated carbon nanospheres in water

Liquid phase levulinic acid hydrogenation into γ-valerolactone in 1,4-dioxane as a solvent (165°C, 20 bar) was studied over a range of Ru monometallic catalysts using mesoporous carbon material Sibunit as a support. In addition to the catalyst prepared by impregnation with RuCl3∙nH2O (0.1 M) followed by reduction in H2, size-controlled Ru(NPs)/Sibunit catalysts were synthesized by immobilization of polyvinylpyrrolidone (PVP) stabilized Ru nanoparticles (NPs) (dRu=2.4 nm). Сarbon supported colloidal Ru NPs were not studied earlier in levulinic acid hydrogenation. Activity of colloidal Ru(NPs)/Sibunit catalysts was found to be lower than that of impregnated Ru/Sibunit which could be attributed to hampering effect of PVP. However, colloidal Ru(NPs)/Sibunit purified by thermal treatment in air (180°C) followed by reduction in H2 (400°C) exhibited the same activity as impregnated one yielding 93% γ-valerolactone at 100% levulinic acid conversion. Applicability of supported PVP-assisted colloidal Ru NPs in hydrogenation of levulinic acid illustrates a potential to prepare more efficient catalysts for this reaction with a desired particle size. The catalysts were characterized by TEM, XRF, and N2 physisorption to compare their physical chemical properties

Catalytic conversion of biomass-derived levulinic acid into γ-valerolactone using iridium nanoparticles supported on carbon nanotubes