Selective Hydrogenation Of Levulinic Acid Research Articles

Synthesis of Nanostructured Molybdenum Carbide as Catalyst for the Hydrogenation of Levulinic Acid to γ-Valerolactone

The effect of the morphology and size of unsupported molybdenum carbide (β-Mo2C) was investigated in the selective hydrogenation of levulinic acid to γ-valerolactone (GVL) in aqueous phase. Nanostructured β-Mo2C was synthetized by two different approaches: (i) using multiwalled carbon nanotubes (CNT) as both hard template and source of carbon and; (ii) using 1D nanostructured α-MoO3 as precursor. Depending on the type of synthesis used, the morphology of the resulting β-Mo2C was different. Well-oriented β-Mo2C nanoparticles with a fibril morphology were formed when CNTs were used as hard template and source of carbon at 700 °C for 6 h under inert environment, while well-defined β-Mo2C 1D nanostructures were formed after carburization of the nano-sized α-MoO3 precursor at 650 °C/2 h under 20 % (v/v) CH4/H2 atmosphere. The catalytic performance of the materials was investigated at 30 bar H2 and 180 °C in a batch reactor and compared with a Mo2C synthesized by temperature-programmed carburization of commercial MoO3. The β-Mo2C 1D nanostructures presented a relatively higher activity than the others probably as a result of more exposed active sites, confirmed by the higher CO chemisorption uptake. All of the catalysts were highly selective to GVL (>85 %). Deep hydrogenation products such as 1,4 pentanediol and methyltetrahydrofuran were observed in minor amounts, underlining the hydrogenation potential of molybdenum carbide based materials.

Effective Upgrade of Levulinic Acid into γ-Valerolactone over an Inexpensive and Magnetic Catalyst Derived from Hydrotalcite Precursor

A low-cost and magnetic catalyst derived from a hydrotalcite precursor was developed for selective hydrogenation of levulinic acid (LA) into γ-valerolactone (GVL) in a methanol solvent. An excellent GVL yield of 98.1% with full LA conversion was achieved at 415 K over a magnetic and recyclable Ni4.59Cu1Mg1.58Al1.96Fe0.70 catalyst. The specific textural and chemical characteristics of prepared samples were identified by ICP-AES, XRD, XPS, NH3-TPD, Py-IR, and nitrogen physisorption. Various parameters such as Ni/Cu molar ratio, reduction temperature, and reaction solvent played a great role in LA hydrogenation. The recycling experiments revealed that reactivated Ni4.59Cu1Mg1.58Al1.96Fe0.70 maintained excellent activity, stability, and magnetism after being used five times, which made Ni4.59Cu1Mg1.58Al1.96Fe0.70 a potential catalyst for the production of GVL in industry.

Selective hydrogenation of levulinic acid to 1,4-pentanediol in water using a hydroxyapatite-supported Pt–Mo bimetallic catalyst

Hydroxyapatite-supported Pt–Mo bimetallic nanoparticles (Pt–Mo/HAP) catalyze the selective transformation of levulinic acid to 1,4-pentanediol under aqueous conditions.

Selective hydrogenation of levulinic acid to γ-valerolactone over a Ru/Mg–LaO catalyst

Ruthenium on a base support was developed for the conversion of biomass derived levulinic acid to γ-valerolactone at low temperature and pressure. γ-Valerolactone synthesis which can replace ethanol in petrol and in the production of jet fuels.

Selective hydrogenation of levulinic acid to valeric acid and valeric biofuels by a Pt/HMFI catalyst

Valeric acid and valeric biofuels are obtained in high yield by direct hydrogenation of levulinic acid catalyzed by Pt/HMFI under relatively mild conditions (2 or 8 bar H2, 200 °C), driven by cooperation of the metal and support Brønsted acid sites.

Aqueous phase hydrogenation of levulinic acid to 1,4-pentanediol

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).

RuSn bimetallic catalysts for selective hydrogenation of levulinic acid to γ-valerolactone

Carbon-supported ruthenium catalysts containing different amounts of tin were studied for the hydrogenation of levulinic acid (LA) to gamma-valerolactone (GVL) in a 2-sec-butyl-phenol (SBP) solvent. Results from reaction kinetics measurements (453K and 35bar H2) showed that the Ru/C catalyst was initially more active for hydrogenation of both LA and SBP (i.e., 0.051s−1 for conversion of LA to GVL), followed by continuous deactivation versus time on stream. In contrast, the catalyst containing equal amounts of Ru and Sn had a lower activity for LA to GVL conversion (0.005s−1), but displayed stable activity versus time on stream and showed 100% selectivity for hydrogenation of LA versus the SBP solvent. Increasing the amount of Sn to a 1 to 4 Ru:Sn atomic ratio creates an additional phase, β-Sn, that is not active for hydrogenation, leaches into the SBP solvent, and sinters under reaction conditions. Results from CO and O2 chemisorption and electron microscopy measurements indicated that the Ru-based metal particles did not leach or sinter at reaction conditions, and that the surfaces of these particles became progressively enriched with Sn as the Sn-loading increases. In addition, Sn did not significantly leach from the catalysts when present as an intermetallic alloy with Ru, such as Ru2Sn3 and Ru3Sn7. Using LA produced from corn stover, the RuSn4/C catalyst was stable and demonstrated that it is a promising catalyst to produce valuable chemicals and fuels from real biomass.

Cu–ZrO2 nanocomposite catalyst for selective hydrogenation of levulinic acid and its ester to γ-valerolactone

Several copper based catalysts were prepared, characterized and evaluated for the hydrogenation of levulinic acid and its methyl ester. Among these, nanocomposites of Cu–ZrO2 and Cu–Al2O3 quantitatively catalyzed the hydrogenation of levulinic acid and its methyl ester to give 90–100% selectivity to γ-valerolactone in methanol and water respectively. Both the Cu–ZrO2 and Cu–Al2O3 nanocomposites were prepared by the co-precipitation method using mixed precursors under controlled conditions. XRD results showed that the main active phase of the reduced Cu–ZrO2 catalyst was metallic copper and particle size was found to be of 10–14 nm by HRTEM. The active metal leaching was at a maximum for the Cu–Al2O3 catalyst in a water medium due to the formation of a copper–carboxylate complex that was blue in colour. Surprisingly, copper leaching was completely suppressed in the case of the Cu–ZrO2 catalyst in methanol in spite of the substrate loading was increased from 5 to 20% w/w. The excellent recyclability of the Cu–ZrO2 catalyst with complete LA conversion and >90% GVL selectivity makes it a sustainable process having a commercial potential.

Selective hydrogenation of levulinic acid to γ-valerolactone over carbon-supported noble metal catalysts

Selective hydrogenation of biomass derived levulinic acid (LA) to γ-valerolactone (GVL) has been efficiently catalyzed by Ru, Pt and Pd noble metal supported on carbon under vapor phase in a continuous down flow fixed-bed reactor system. Among the catalysts, 5 wt.% Ru/C gave GVL with 100% selectivity at 100% LA conversion up to 240 h (10 days) without loss in its activity. The higher catalytic activity and product selectivity of 5 wt.% Ru/C catalyst has been attributed to the higher dispersion of metallic Ru over carbon in nano-sizes compared to Pt and Pd catalysts.