Catalytic etherification of 5-hydroxymethylfurfural into 5-ethoxymethyfurfural over sulfated bimetallic SO42−/Al-Zr/KIT-6, a Lewis/Brønsted acid hybrid catalyst (original) (raw)
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Catalysis Today, 2011
The etherification of 5-hydroxymethyl-2-furfural (HMF) with ethanol is studied over a series of mesoporous silica catalysts (Al-MCM-41 materials with different Si/Al ratio, and zirconia or sulfated zirconia supported over SBA-15) and compared with the behavior of H 2 SO 4 and Amberlyst ® 15. The observed reaction products were 5-(ethoxymethyl)furan-2-carbaldehyde (EMF), 1,1-dietoxy ethane (DE) and ethyl 4-oxopentanoate (EOP). The selectivity to EMF and EOP is closely related to the presence of Lewis and/or Brønsted acidity on the catalyst, while the formation of DE is probably related to defect sites. The latter, being less reactive, catalyze the side reaction to DE only when strong Lewis and/or Brønsted acid sites are absent. Catalysts with only a strong Brønsted acidity react selectively to form EOP. When strong Lewis acid sites are present in the catalyst, e.g. by introducing ZrO 2 in SBA-15 or when extra-framework isolated Al 3+ sites are present in the mesoporous channels, a high selectivity to EMF was observed. The results indicate that EMF, DE or EOP can be obtained selectively by direct reaction of HMF with bioethanol by tuning the acidity of the catalyst. EMF is a value biodiesel component, but the results also evidence the possibility to obtain selectively EOP in a one-step reaction, opening interesting perspectives to produce valeric biofuels by subsequent selective hydrogenation.
Recent progress in the development of advanced biofuel 5-ethoxymethylfurfural
BMC Energy, 2020
Biomass-derived 5-ethoxymethylfurfural (EMF) with excellent energy density and satisfactory combustion performance holds great promise to meet the growing demands for transportation fuels and fuel additives to a certain extent. In this review, we summarized the relative merits of the EMF preparation from different feedstocks, such as platform chemicals, biomass sugars and lignocellulosic biomass. Advances for EMF synthesis over homogeneous (i.e. inorganic acids and soluble metal salts), heterogeneous catalysts (i.e. zeolites, heteropolyacid-based hybrids, sulfonic acid-functionalized catalysts, and others) or mixed-acid catalysts were performed as well. Additionally, the emerging development for the EMF production was also evaluated in terms of the different solvents system (i.e. single-phase solvents, biphasic solvents, ionic liquids, and deep eutectic solvents). It is concluded with current challenges and prospects for advanced biofuel EMF preparation in the future.
Catalysis Science & Technology, 2020
mixed oxides with different amounts of silica (0-50 wt%) were prepared by a simple sol-gel method. These catalysts were tested in a cascade reaction of furfural and 5-hydroxymethyl furfural (HMF) with 2-butanol to form the corresponding alcohols or ethers through a combination of transfer hydrogenation and etherification processes under mild conditions. The selectivity can be finely tuned by changing the silica content which heavily impacts the acid-base properties. On pure ZrO 2 , featuring acid-base pairs, only the catalytic transfer hydrogenation occurs leading to alcohol products. In contrast, on ZrSi30 the etherification reaction is strongly favored owing to near one-to-one Lewis and Brønsted acid sites. Ethers can thus be produced in high yields (≥90%), in particular the highly valuable diether of 5-hydroxymethyl furfural. The catalysts were characterized by N 2 and CO 2 absorption isotherms, FT-IR of adsorbed pyridine, 2-propanol TPD, and STEM-EDX mapping. For the first time we show that the tuning of acid-base properties by simple silica addition, with the somewhat unexpected rise of Brønsted acidity, may represent the starting point for the development of cheap but highly active and selective catalysts for furfural and HMF transformation.
Energy Conversion and Management, 2014
A series of acid-base bifunctional hybrid nanospheres prepared from the self-assembly of basic amino acids and phosphotungstic acid (HPA) with different molar ratios were employed as efficient and recyclable catalysts for synthesis of liquid biofuel 5-ethoxymethylfurfural (EMF) from various carbohydrates. A high EMF yield of 76.6%, 58.5%, 42.4%, and 36.5% could be achieved, when fructose, inulin, sorbose, and sucrose were used as starting materials, respectively. Although, the acid-base bifunctional nanocatalysts were inert for synthesis of EMF from glucose based carbohydrates, ethyl glucopyranoside in good yields could be obtained from glucose in ethanol. Moreover, the nanocatalyst functionalized with acid and basic sites was able to be reused several times with no significant loss in catalytic activity.
Renewable Energy, 2019
Biomass-derived ethyl levulinate (EL) is currently deemed as a promising fuel bioadditive to improve (bio)diesel combustion performance without the sacrifice of its octane number. In this contribution, a range of ZreAl bimetallic catalysts were prepared for the cascade conversion of furfural to EL by the integration of transfer hydrogenation and ethanolysis in ethanol. The ratio of Lewis to Brønsted acid sites (L/B) could be tuned by the ratio of Al 2 O 3 to ZrO 2 over SBA-15 support. Among these catalysts, ZreAl/ SBA-15(30:10) with appropriate L/B ratio of 2.25 exhibited an outstanding catalytic performance to give a furfural (FF) conversion up to 92.8% with a EL selectivity as high as 71.4% at 453 K in 3 h.
2009
SO 4 2À /ZrO 2 and SO 4 2À /ZrO 2-Al 2 O 3 catalysts were prepared by impregnation of Zr(OH) 4 and Zr(OH) 4-Al(OH) 3 with ethylene dichloride solution of chlorosulfonic acid, and characterized by ICP-AES, BET, XRD, NH 3-TPD, CO 2-TPD and FTIR of adsorbed pyridine. The catalysts were used in the catalytic conversion of glucose to 5-hydroxymethylfurfural. An optimized 5-hydroxymethylfurfural yield of 47.6% was obtained within 4 h at 403 K over SO 4 2À /ZrO 2-Al 2 O 3 with Zr-Al mole ratio of 1:1. The catalyst with higher acidity and moderate basicity was more favorable for the formation of the target product.
Etherification of 5-hydroxymethylfurfural using a heteropolyacid supported on a silica matrix
Molecular Catalysis, 2020
In this work, Preyssler-type heteropolyacids and their silica-included counterparts were employed in the etherification reaction of HMF and n-BuOH. Materials were synthesized with a Preyssler acid load of 12.5% w/w using the sol-gel technique, which improved surface areas and modulated their acid strength. Prepared materials were used as heterogeneous solid acid catalysts in the selective etherification of 5-hydroxymethylfurfural (HMF) to 5-butoxymethylfurfural (5BMF). The high catalytic performance of the bulk Preyssler acids is related to their high acid strength, while selectivity related to the decrease in acidity by the inclusion effects. Different reaction parameters were optimized, with PWMo(12.5%)@SiO 2 exhibited the highest catalytic activity with 89% of HMF conversion and 73% of 5BMF selectivity. The catalyst is reusable up to five cycles without noticeable decrease in selectivity.
ChemPlusChem, 2012
ABSTRACT The synthesis of fine chemicals from the platform molecules obtained through the degradation of the cellulosic and lignocellulosic biomass is a most widely envisioned approach toward the implementation of renewable feedstocks for fuels and chemicals. Significant advances have been made in the synthesis of furan-based polyester building block 2,5-furandicarboxylic acid (FDCA) and related compounds such as 2,5-bis(hydroxymethyl)furan and 2,5-bis(hydroxymethyl)tetrahydrofuran from biomass-derived 5-hydroxymethylfurfural (HMF) by using homogeneous and nanoparticulate catalysts. This review provides a survey of selective aerobic oxidation of HMF to give FDCA as the end-product. The article highlights the fundamental aspects of preferring nanoparticulate catalysts over the conventional supported metal catalysts for the synthesis of FDCA with high selectivity. Another objective of the review is to discuss how efficiently the HMF-platform produces biofuels, including gasoline blendstock 2,5-dimethylfuran (DMF), 5-ethoxymethylfurfural (EMF), and ethyl levulinate (EL), which are competitive of existing liquid fuels.
Renewable and Sustainable Energy Reviews, 2017
5-Hydroxymethylfurfural (HMF) belongs to the group of "drop-in biofuels" and platform molecule of prime importance. Synthesis of HMF from various sugar sources has traversed a long span of time and has witnessed various modifications viz., use of heterogeneous catalysts over homogeneous catalysts, employment of organic phase over aqueous, introduction of biphasic systems to overcome side reaction limitations and still counting. Every modification has been carried out with the objective of improved selectivity and product synthesis, cost and energy optimization, and a shift towards greener process over existing methods. Use of lignocellulosic biomass instead of commercial sugars also finds applicability in direct HMF synthesis along with levulinic acid, furfural etc. However, low yields from these abundant, cheap and readily available sugar sources are still ideal for scale-up of the process strategies. Among large pool of studies available in this area, current review presents the advantages imparted towards HMF synthesis with the advent of heterogeneous catalysis over the course of time and various reaction systems evolved to meet the steeping demand of HMF, specifically from common carbohydrate sources. Special attention has been paid to understand the mechanism of modifications imparted to various solid catalysts for improved HMF synthesis.