Ru Catalysts Supported on Commercial and Biomass-Derived Activated Carbons for the Transformation of Levulinic Acid into γ-Valerolactone under Mild Conditions

Abstract

Ru catalysts (1 wt.%) supported on commercial and biomass-derived activated carbons (AC) have been prepared, thoroughly characterized, and used in the hydrogenation of levulinic acid to produce gamma-valerolactone (GVL). This is an important platform compound that plays a key role in the production of liquid fuels and that can also be used, for example, as a food flavoring agent, antifreeze, and solvent. The study focuses on the influence of the carbon support characteristics, such as porous texture and acidity, on the properties and performance (LA conversion and selectivity to GVL) of the catalysts. Catalytic activity tests have been carried out at 170 °C and also in noticeably milder conditions (70 °C) to implement a less energy-demanding process. All the catalysts show high LA conversion and GVL yield at 170 °C, while at 70 °C, important differences between them, related to the support properties, have been found. The catalysts prepared with more acidic supports show better catalytic properties: very good catalytic performance (98% LA conversion and 77% selectivity to GVL) has been obtained in mild temperature conditions.

Efficient and labor-saving Ru/C catalysts for the transformation of levulinic acid into γ-valerolactone under mild reaction conditions

“…27,28 Several researchers have focused their work on developing greener processes for the transformation of LA into GVL. Usually, the target experimental variables to improve the system are the nature and content of the metal used as active phase, 29,30 the type of support, 16,22,[24][25][26] including nature and physico-chemical properties, 16,31 and the operation conditions, such as temperature, pressure and/or reaction time. 9 Some of the indicated studies have led to good results, although in many cases the catalysts' preparation procedures and the catalytic methods involve non-green solvents and high-priced activation processes and/or reaction conditions.…”

Selective hydrodeoxygenation of levulinic acid to γ-valerolactone over Ru supported on functionalized carbon nanofibers

“…18,19 In contrast to metal oxides, carbonaceous supports have been demonstrated to be superior, maintaining Ru/C catalytic performance aer different operation cycles. 16,20,21 The unique properties of carbon nanobers (CNFs) have made these materials very promising in numerous applications. Nevertheless, in most cases, their huge potential is limited by their hydrophobic and inert surfaces, which is the reason why different modication techniques have been developed.…”

“…18,19 In contrast to metal oxides, carbonaceous supports have been demonstrated to be superior, maintaining Ru/C catalytic performance after different operation cycles. 16,20,21…”

Functionalized Biochars as Supports for Ru/C Catalysts: Tunable and Efficient Materials for γ-Valerolactone Production

“…Nevertheless, the catalysts supported on metal oxides become unstable in the aqueous environment, especially in acidic conditions, due to the existence of surface hydroxyl groups (-OH) that decline catalysts’ activity and stability drastically in all HDO steps. On the contrary, carbon-based supports appear to be much more stable and maintain the Ru metal nanoparticles performance over extended periods of operation [ 33 , 34 , 35 , 36 ].…”