Selective Synthesis of Levulinic Ester from Furfural Catalyzed by Hierarchical Zeolites (original) (raw)
Related papers
Aldol Condensation of Biomass-Derived Levulinic Acid and Furfural over Acid Zeolites
ACS Sustainable Chemistry & Engineering, 2020
Acid-catalysed cross condensation between furfural and levulinic acid is presented in this work as an alternative for manufacturing C10 chemicals from renewable platform molecules. First experiments conclude that the neutralization of the carboxylic group of levulinic acid is required to prevent side reactions such as cyclization. Two C10 products are obtained, suggesting two parallel reaction mechanisms. Different reaction conditions (temperatures and initial reactants ratios) have been tested, and results were used to propose a kinetic model. The role of the properties of different catalysts is also studied, analysing the activity, selectivity and acidities of different zeolites structures (ZSM-5, MOR, BETA), observing a clear correspondence between medium-strength acidity and the production of the most stable product. A high selectivity to this compound is required to reduce the permanent adsorption and oligomerization of the starting materials, the main deactivation cause identified in this process. Thus, the best results were obtained with ZSM-5 (23) at 423 K and a LA:FFL ratio 2:1, with 50 % of products yield and almost negligible relevance of side reactions (carbon balance after 24 h: 91 %), observing a good behaviour after three reusability cycles without any regeneration.
Catalysis Communications, 2014
A series of bimodal micro-mesoporous H/BEA zeolite derivatives were prepared by the post-synthesis modification of H/BEA zeolite by NaOH (0.05 M-1.2 M) treatment. Samples were characterized by powder XRD, low temperature nitrogen adsorption/desorption, temperature programmed desorption of ammonia and ICP. The mesopore formation was found to play a crucial role in liquid phase esterification of levulinic acid with ethanol. The enhanced catalytic activity of a bimodal micro-mesoporous H/BEA zeolite derivative (H/BEA 0.10) prepared by treatment with 0.1M NaOH can be mainly attributed to the high mesoporosity coupled with better preserved crystallinity and acidic properties.
2019
A highly efficient catalyst system was developed for the one-pot transformation of furfural to c-valerolactone (GVL) in an open system. The cascade of two Meerwein Ponndorf Verley (MPV) reductions, ring-opening and esterification reactions was catalyzed by a physical mixture of Zr-and Al-HY zeolites where the proportion and strength of Lewis and Brønsted acid sites could be independently optimized. The excellent activity of Zr-HY zeolites for the MPV reduction of furfural and levulinate ester with 2-pentanol as hydrogen donor was attributed to the larger pore size of HY-zeolites and stronger Lewis acidic sites compared to Zr-Beta. Al-HY zeolites were more effective as Brønsted acid than Al-Beta because they converted furfuryl ether to levulinate ester rather than to b-angelica lactone. The dual catalytic system comprising Zr-HY (Si/Zr 20) and Al-HY (Si/Al 6) exhibited remarkably high catalytic activity with GVL yields of 85% after only 5 h at 120°C.
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
The one-pot conversion of biomass-derived platform molecules such as levulinic acid (LA) and furfural (FAL) into γ-valerolactone (GVL) is challenging because of the need for adequate multi-functional catalysts and high-pressure gaseous hydrogen. As a more sustainable alternative, here we describe the transfer hydrogenation of LA to GVL using isopropanol as a hydrogen donor over a Zr-modified beta zeolite catalyst in a continuous fixed-bed reactor. A stable sustained production of GVL was achieved from the levulinic acid, with both high LA conversion (ca. 95%) and GVL yield (ca. 90%), for over at least 20 days in continuous operation at 170 °C. Importantly, the small decay in activity can be advantageously overcome by the means of a simple in situ thermal regeneration in the air atmosphere, leading to a complete recovery of the catalyst activity. Key to this outstanding result is the use of a Zr-modified dealuminated beta zeolite with a tailored Lewis/Brønsted acid sites ratio, which...
Angewandte Chemie International Edition, 2013
The development of more carbon efficient and economically viable lignocellulosic biomass conversion technologies is critical for the sustainable production of liquid transportation fuels and chemicals. [1] The molecule g-valerolactone (GVL) has gained attention as a versatile platform chemical for the production of liquid alkenes, as a solvent for biomass processing, as an approved fuel additive, and as a precursor for renewable polymers. [2-4] Biomass-derived GVL is currently produced by the multistep processing of the carbohydrate fractions of lignocelluloses, wherein acid catalysts transform sugars into levulinic acid (LA), and noble-metal catalysts reduce LA to GVL with molecular hydrogen (H 2). [5, 6] This strategy suffers from several limitations that hinder the large-scale manufacture of GVL. In particular, the LA-reduction step necessitates precious-metal catalysts (e.g., Ru or Pt) or high H 2 pressures (> 30 bar), which have been shown to negatively impact the economics of GVL-derived transportation fuels. [7] Formic acid has emerged as an alternative to molecular H 2 , but noble metals and/or harsh conditions are still required to carry out the hydrogenation step. [8, 9] Inexpensive supported transition metals (e.g., Cu/ Al 2 O 3) are active but suffer from leaching and/or sintering during the reaction. [10] For the large-scale production of GVL, catalytic schemes are required that maximize product yields without the use of precious metals, high H 2 pressure, or an excessive number of unit operations. Transfer-hydrogenation (TH) reactions, such as the Meerwein-Ponndorf-Verley (MPV) reaction, offer an attractive alternative to molecular H 2 for the reduction of targeted functional groups. The interaction between the catalyst, the hydrogen donor, and the acceptor molecule can be modulated to impact activity and selectivity. Many catalysts are active for TH reactions, including organometallic compounds, transition metals, and metal oxides featuring acid/base properties. [11] Pure-silica zeolites containing a small amount of tetravalent heteroatoms with open coordination sites (e.g., Zr or Sn) have also been used as solid Lewis acids to promote TH reactions.
Obtaining glucose-based 5-hydroxymethylfurfural on large-pore zeolites
Eastern-European Journal of Enterprise Technologies
Obtaining such substances-platforms as, in particular, 5-hydroxymethylfurfural is one of the areas most actively investigated at present. They can act as raw materials for the further production of a new generation of biopolymers, fuels, pharmaceuticals, dietary supplements, and other chemicals. This paper reports the catalysts, synthesized by using methods of ion exchange and impregnation, based on the large-pore zeolites X, Y, and M, which contain the cations of rubidium, lanthanum, calcium, and ammonium. It was found that the zeolites' specific surface was 400‒500 m2/g; the selected synthesis conditions did not cause noticeable destruction of the microporous structure. In the presence of the synthesized catalysts, glucose dehydration in the aqueous medium and in dimethyl sulfoxide was carried out at 150–160 °C. The higher efficiency of polycationic forms of zeolites in a non-aqueous medium has been established. In the latter case, a 40 % yield of 5-hydroxymethylfurfural was a...