Continuous-Flow Hydrogenation of Methyl Levulinate Promoted by Zr-Based Mesoporous Materials

Abstract

Several Zr-based materials, including ZrO 2 and Zr-SBA-15, with different silicon/zirconium molar ratios, and ZrO 2 /Si-SBA-15 (where SBA-15 stands for Santa Barbara Amorphous material no. 15), have been prepared as hydrogenation catalysts. The materials were characterized using different characterization techniques including X-ray diffraction (XRD), N 2 porosimetry, scanning electron microscopy (SEM/EDX), diffuse reflectance infrared Fourier transform spectroscopy (DRIFT) of pyridine adsorption and the pulsed chromatographic method using pyridine and 2,6-dimethylpyridine as probe molecules, mainly, have been employed for the characterization of the structural, textural, and acidic properties of the synthesized materials, respectively. The catalysts have been evaluated in the hydrogenation reaction of methyl levulinate using 2-propanol as hydrogen donor solvent. The reaction conditions were investigated and stablished at 30 bar system pressure with a reaction temperature of 200 • C using around 0.1 g of catalyst and a flow rate of 0.2 mL/min flow rate of a 0.3 M methyl levulinate solution in 2-propanol. All catalysts employed in this work exhibited good catalytic activities under the investigated conditions, with conversion values in the 15-89% range and, especially, selectivity to Υ-valerolactone in the range of 76-100% (after one hour time on stream). The highest methyl levulinate conversion and selectivity was achieved by ZrO 2 /Si-SBA-15 which can be explained by the higher dispersion of ZrO 2 particles together with a highest accessibility of the Zr sites as compared with other materials such as Zr-SBA-15, also investigated in this work.

A comprehensive review of flow chemistry techniques tailored to the flavours and fragrances industries

“…Pineda et al optimised continuous-flow catalytic transfer hydrogenation (CTH) for the synthesis of γ-valerolactone ( 263 ) from lignin-derived methyl levulinate ( 262 ) in flow ( Scheme 63 ) [ 280 – 281 ]. One of the systems operated with a mesoporous acidic material (Si-SBA-15) and iPrOH as the hydrogen donor.…”

“…When a stream of 262 is heated at 200 °C and passed over the catalyst 100% conversion and 95% selectivity to the desired product 263 was achieved. The catalyst was able to operate for over 24 hours with no substantial change in productivity giving a throughput of 30 mmol g −1 h −1 [ 280 ].…”

Mechanochemical Synthesis of Nickel-Modified Metal–Organic Frameworks for Reduction Reactions

“…In this work, the catalytic performance of the as-prepared Ni/UiO-66 materials was evaluated in the transfer hydrogenation reaction of methyl levulinate (ML) to gammavalerolactone (GVL) using a Phoenix continuous-flow reactor (Budapest, Hungary) and 2-propanol as hydrogen donor solvent [35]. The reaction conditions were, in accordance with previously explored reaction conditions [36], 200 • C and 30 bars of pressure. The catalysts (1%Ni/UiO-66, 3%Ni/UiO-66 or 5%Ni/UiO-66) were packed (0.2 g of catalyst per cartridge) in a 30 mm long ThalesNano CatCart.…”

Catalytic Methods in Flow Chemistry

“…Interestingly, the new reactor was based on two aqueous phases dynamically connected via an organic liquid membrane, which enabled substantial enhancement of glucose conversion while avoiding intermediate separation steps. The use of an immobilized glucose isomerase and an acidic resin facilitated catalyst recycling.Zirconium-based mesoporous materials were prepared and used as suitable catalysts for the continuous flow hydrogenation of methyl levulinate [4]. The catalysts were accurately characterized in order to ascertain the structure, texture, and acidic properties.…”

“…Zirconium-based mesoporous materials were prepared and used as suitable catalysts for the continuous flow hydrogenation of methyl levulinate [4]. The catalysts were accurately characterized in order to ascertain the structure, texture, and acidic properties.…”