Search Results (5)

This study determined the optimal production of furfural (FuR) from liquid hydrolysate xylan liquor obtained through a two-stage pretreatment process using NaOH for de-ashing and EtOH for the delignification of raw rice husk (RH). The de-ashing pretreatment was conducted at 150 °C, with 6.0% (w/v) NaOH and a reaction time of 40 min. The optimal conditions for delignification pretreatment, performed using an organosolv fractionation method with EtOH, were a reaction temperature of 150 °C, 60% (v/v) EtOH, 0.25% (w/v) H₂SO₄, and a reaction time of 90 min. Through a two-stage pretreatment process, a liquid hydrolysate in the form of xylan liquor was obtained, which was subjected to an acid catalytic conversion process to produce FuR. The process conditions were varied, with reaction temperatures of 130–170 °C, H₂SO₄ catalyst concentrations of 1.0–3.0 wt.%, and reaction times of 0–90 min. The Response Surface Methodology tool was used to identify the optimal FuR yield from xylan liquor. Ultimately, the optimal process conditions for the acid catalytic conversion were found to be a substrate-to-catalyst ratio of 2:8, a reaction temperature of 168.9 °C, a catalyst concentration of 1.9 wt.%, and a reaction time of 41.24 min, achieving an FuR yield of 67.31%. Full article

In this study, a simple and green protocol to obtain hydrochar and high-added value products, mainly 5-hydroxymethylfurfural (5-HMF), furfural (FU), levulinic acid (LA) and alkyl levulinates, by using the hydrothermal carbonization (HTC) of orange peel waste (OPW) is presented. Process variables, such as reaction temperature (180–300 °C), reaction time (60–300 min), biomass:water ratio and initial pH were investigated in order to find the optimum conditions that maximize both the yields of solid hydrochar and 5-HMF and levulinates in the bio-oil. Data obtained evidence that the highest yield of hydrochar is obtained at a 210 °C reaction temperature, 180 min residence time, 6/1 w/w orange peel waste to water ratio and a 3.6 initial pH. The bio-products distribution strongly depends on the applied reaction conditions. Overall, 180 °C was found to be the best reaction temperature that maximizes the production of furfural and 5-HMF in the presence of pure water as a reaction medium. Full article

Glucose–carbon hybrids were synthetized with different carbon materials, namely carbon nanotubes, reduced graphene oxide, carbon black and activated carbon by a hydrothermal treatment. These carbon hybrids were used as Pt-supports (1 wt.%) for the furfural (FUR) hydroconversion in the gas phase at mild operating conditions (i.e., P = 1 atm and T = 200 °C). The physicochemical properties (porosity, surface chemistry, Pt-dispersion, etc.) were analyzed by different techniques. Glucose–carbon hybrids presented apparent surface areas between 470–500 m² g⁻¹, a neutral character and a good distribution of small Pt-nanoparticles, some large ones with octahedral geometry being also formed. Catalytic results showed two main reaction pathways: (i) FUR hydrogenation to furfuryl alcohol (FOL), and (ii) decarbonylation to furane (FU). The products distribution depended on the reaction temperature, FOL or FU being mainly produced at low (120–140 °C) or high temperatures (170–200 °C), respectively. At intermediate temperatures, tetrahydrofurfuryl alcohol was formed by secondary FOL hydrogenation. FUR hydroconversion is a structure-sensitive reaction, rounded-shape Pt-nanoparticles producing FU, while large octahedral Pt-particles favor the formation of FOL. Pt-catalysts supported on glucose–carbon hybrids presented a better catalytic performance at low temperature than the catalyst prepared on reference material, no catalyst deactivation being identified after several hours on stream. Full article

In the pursuit of establishing a sustainable biobased economy, valorization of lignocellulosic biomass is increasing its value as a feedstock. Nevertheless, to achieve the integrated biorefinery paradigm, the selective fractionation of its complex matrix to its single constituents must be complete. This review presents and examines the novel catalytic pathways to form furfuryl alcohol (FuOH) from xylose in a one-pot system. This production concept takes on chemical, thermochemical and biochemical transformations or a combination of them. Still, the bulk of the research is targeted to develop heterogeneous catalytic systems to synthesize FuOH from furfural and xylose. The present review includes an overview of the economic aspects to produce this platform chemical in an industrial manner. In the last section of this review, an outlook and summary of catalytic processes to produce FuOH are highlighted. Full article

The hydrodeoxygenation of furfural (FU) was investigated over Fe-containing MgO catalysts, on a continuous gas flow reactor, using methanol as a hydrogen donor. Catalysts were prepared either by coprecipitation or impregnation methods, with different Fe/Mg atomic ratios. The main product was 2-methylfuran (MFU), an important highly added value chemical, up to 92% selectivity. The catalyst design helped our understanding of the impact of acid/base properties and the nature of iron species in terms of catalytic performance. In particular, the addition of iron on the surface of the basic oxide led to (i) the increase of Lewis acid sites, (ii) the increase of the dehydrogenation capacity of the presented catalytic system, and (iii) to the significant enhancement of the FU conversion to MFU. FTIR studies, using methanol as the chosen probe molecule, indicated that, at the low temperature regime, the process follows the typical hydrogen transfer reduction, but at the high temperature regime, methanol dehydrogenation and methanol disproportionation were both presented, whereas iron oxide promoted methanol transfer. FTIR studies were performed using furfural and furfuryl alcohol as probe molecules. These studies indicated that furfuryl alcohol activation is the rate-determining step for methyl furan formation. Our experimental results clearly demonstrate that the nature of iron oxide is critical in the efficient hydrodeoxygenation of furfural to methyl furan and provides insights toward the rational design of catalysts toward C–O bonds’ hydrodeoxygenation in the production of fuel components. Full article