Catalytic Transfer Hydrogenation and Acid Reactions of Furfural and 5-(Hydroxymethyl)furfural over Hf-TUD-1 Type Catalysts (original) (raw)
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ChemSusChem, 2016
Iron-based heterogeneous catalysts, which were generally prepared by pyrolysis of iron complexes on supports at elevated temperature, were found to be capable of catalyzing the transfer hydrogenation of furfural (FF) to furfuryl alcohol (FFA). The effects of metal precursor, nitrogen precursor, pyrolysis temperature, and support on catalytic performance were examined thoroughly, and a comprehensive study of the reaction parameters was also performed. The highest selectivity of FFA reached 83.0 % with a FF conversion of 91.6 % under the optimal reaction condition. Catalyst characterization suggested that iron cations coordinated by pyridinic nitrogen functionalities were responsible for the enhanced catalytic activity. The iron catalyst could be recycled without significant loss of catalytic activity for five runs, and the destruction of the nitrogen-iron species, the presence of crystallized Fe2 O3 phase, and the pore structure change were the main reasons for catalyst deactivation.
Frontiers in Chemistry, 2022
The biomass-derived platform chemicals furfural and 5-(hydroxymethyl)furfural (HMF) may be converted to α-angelica lactone (AnL) and levulinic acid (LA). Presently, LA (synthesized from carbohydrates) has several multinational market players. Attractive biobased oxygenated fuel additives, solvents, etc., may be produced from AnL and LA via acid and reduction chemistry, namely alkyl levulinates and γ-valerolactone (GVL). In this work, hierarchical hafniumcontaining multifunctional Linde type L (LTL) related zeotypes were prepared via top-down strategies, for the chemical valorization of LA, AnL and HMF via integrated catalytic transfer hydrogenation (CTH) and acid reactions in alcohol medium. This is the first report of CTH applications (in general) of LTL related materials. The influence of the post-synthesis treatments/conditions (desilication, dealumination, solid-state impregnation of Hf or Zr) on the material properties and catalytic performances was studied. AnL and LA were converted to 2-butyl levulinate (2BL) and GVL in high total yields of up to ca. 100%, at 200°C, and GVL/2BL molar ratios up to 10. HMF conversion gave mainly the furanic ethers 5-(sec-butoxymethyl)furfural and 2,5-bis(secbutoxymethyl)furan (up to 63% total yield, in 2-butanol at 200°C/24 h). Mechanistic, reaction kinetics and material characterization studies indicated that the catalytic results depend on a complex interplay of different factors (material properties, type of substrate). The recovered-reused solids performed steadily.
Catalysts, 2015
The one-pot catalytic reductive etherification of furfural to 2-methoxymethylfuran (furfuryl methyl ether, FME), a valuable bio-based chemical or fuel, is reported. A large number of commercially available hydrogenation heterogeneous catalysts based on nickel, copper, cobalt, iridium, palladium and platinum catalysts on various support were evaluated by a high-throughput screening approach. The reaction was carried out in liquid phase with a 10% w/w furfural in methanol solution at 50 bar of hydrogen. Among all the samples tested, carbon-supported noble metal catalysts were found to be the most promising in terms of productivity and selectivity. In particular, palladium on charcoal catalysts show high selectivity (up to 77%) to FME. Significant amounts of furfuryl alcohol (FA) and 2-methylfuran (2-MF) are observed as the major by-products.
ACS Catalysis
Biomass conversion to fuels and chemicals provides sustainability, but the highly oxygenated nature of a large fraction of biomass-derived molecules requires removal of the excess oxygen and partial hydrogenation in the upgrade, typically met by hydrodeoxygenation processes. Catalytic transfer hydrogenation is a general approach in accomplishing this with renewable organic hydrogen donors, but mechanistic understanding is currently lacking. Here, we elucidate the molecular level reaction pathway of converting hemicellulose-derived furfural to 2-methylfuran on a bifunctional Ru/RuO x /C catalyst using isopropyl alcohol as the hydrogen donor via a combination of isotopic labeling and kinetic studies. Hydrogenation of the carbonyl group of furfural to furfuryl alcohol proceeds through a Lewis acid-mediated intermolecular hydride transfer and hydrogenolysis of furfuryl alcohol occurs mainly via ring-activation involving both metal and Lewis acid sites. Our results show that the bifunctional nature of the catalyst is critical in the efficient hydrodeoxygenation of furanics and provides insights toward the rational design of such catalysts.
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.
Catalysts
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 regi...
Furfurals As Chemical Platform For Biofuels Production
Methodologies, 2015
In this chapter we present a review of the different conversion strategies for the catalytic upgrading of furfurals, specifically furfural and hydroxymethyl furfural, which are two chemical building blocks from lignocellulosic biomass for the production of transportation fuels, as well as useful acids, aldehydes, alcohols and amines. Reactions and catalysts for aldolcondensation, etherification, hydrogenation, decarbonylation and ring opening of furfurals are discussed. Specific examples are reviewed for hydrogenation and decarbonylation with emphasis on reaction pathways and kinetics analysis, comparing the behaviour of different metal catalysts.
The liquid phase catalytic hydrogenation of furfural to furfuryl alcohol
Catalysis Today, 2018
The results of the study of palladium catalysts in the selective hydrogenation of furfural to furfural alcohol are presented. A comparison of the properties of palladium catalytic systems prepared on different supports (aluminium oxide, hypercrosslinked polystyrene and magnetite/hypercrosslinked polystyrene) is carried out. It is shown that the nature of the support has a significant impact on both the morphology of the catalyst and its activity in the selective hydrogenation of furfural. The most effective catalyst was magnetically recoverable 3 % Pd/Fe3O4/HPS, in the presence of which the conversion of furfural was> 95% with selectivity for furfuryl alcohol> 94 %.