144850-49-7Relevant articles and documents
Highly efficient Nb2O5 catalyst for aldol condensation of biomass-derived carbonyl molecules to fuel precursors
Jing, Yaxuan,Xin, Yu,Guo, Yong,Liu, Xiaohui,Wang, Yanqin
, p. 1168 - 1177 (2019)
Aldol condensation is of significant importance for the production of fuel precursors from biomass-derived chemicals and has received increasing attention. Here we report a Nb2O5 catalyst with excellent activity and stability in the aldol condensation of biomass-derived carbonyl molecules. It is found that in the aldol condensation of furfural with 4-heptanone, Nb2O5 has obviously superior activity, which is not only better than that of other common solid acid catalysts (ZrO2 and Al2O3), more importantly, but also better than that of solid base catalysts (MgO, CaO, and magnesium-aluminum hydrotalcite). The detailed characterizations by N2 sorption/desorption, NH3-TPD, Py-FTIR and DRIFTS study of acetone adsorption reveal that Nb2O5 has a strong ability to activate the C=O bond in carbonyl molecules, which helps to generate a metal enolate intermediate and undergo the nucleophilic addition to form a new C–C bond. Furthermore, the applicability of Nb2O5 to aldol condensation is extended to other biomass-derived carbonyl molecules and high yields of target fuel precursors are obtained. Finally, a multifunctional Pd/Nb2O5 catalyst is prepared and successfully used in the one-pot synthesis of liquid alkanes from biomass-derived carbonyl molecules by combining the aldol condensation with the sequential hydrodeoxygenation.
Preparation of two different crystal structures of cerous phosphate as solid acid catalysts: Their different catalytic performance in the aldol condensation reaction between furfural and acetone
Li, Wenzhi,Su, Mingxue,Yang, Tao,Zhang, Tingwei,Ma, Qiaozhi,Li, Song,Huang, Qifu
, p. 16919 - 16928 (2019)
Liquid fuel intermediates can be produced via aldol condensation reactions through furan aldehydes and ketones driven from biomass. It was found that cerous phosphate (CP) with two different crystal structures (hexagonal and monoclinic structure), which was tailored by different hydrothermal temperature (120 °C for the hexagonal structure and 180 °C for the monoclinic structure) and calcination temperature (900 °C for the monoclinic structure) as a solid acid catalyst, exhibit high catalytic performance in aldol condensation between furfural and acetone. The CP with hexagonal structure gave 89.1% conversion of furfural with 42% yield of 4-(2-furyl)-3-buten-2-one (FAc) and 17.5% of yield of 1,5-di-2-furanyl-1,4-pentadien-3-one (F2Ac), much higher than CP with monoclinic structure. However, both furfural conversion and aldol product yield increased from 82.3% to 96% and from 50.5% to 68.4%, respectively, for CP with the monoclinic structure after calcination owing to the higher amount of acid of catalyst after calcination but decreased continuously for CP with hexagonal structure after calcination because of its rapidly reduced BET surface area and total pore volume. The results indicated that calcination affects significantly the physical-chemical properties of CP catalysts, which influence subsequently the catalytic performance in the aldol condensation reaction. Recycling experiments showed that the catalytic performance after five number runs for CP with monoclinic structure after calcination was acceptable but was not ideal for CP with hexagonal structure owing to its poor hydrothermal stability.
Ultrafinely dispersed Pd nanoparticles on a CN@MgO hybrid as a bifunctional catalyst for upgrading bioderived compounds
Li, Mingming,Xu, Xuan,Gong, Yutong,Wei, Zhongzhe,Hou, Zhaoyin,Li, Haoran,Wang, Yong
, p. 4371 - 4377 (2014)
A novel and sustainable synthesis of a Pd/CN@MgO catalyst is presented here, offering a bifunctional catalyst with high catalytic activity towards a tandem aldol condensation-hydrogenation reaction of furfural with acetone in a one-pot reactor. The incorporation of biomass based hydrophilic N-containing carbon (CN) in the catalyst provides a subtle but elegant method to control the good water dispersibility, the reaction stability, and the ultrafine dispersion of palladium particles (2.2 nm in average size) in the bifunctional catalyst Pd/CN@MgO. With such improved features, an impressive 99% furfural conversion and 95% selectivity for the hydrogenated products (saturated ketones) was obtained by using Pd/CN@MgO as a novel bifunctional catalyst in the reported tandem reaction. This catalyst design strategy and the high efficiency of the catalyst in the reported system offer potential for the preparation of bi/multifunctional catalysts and the one-pot synthesis of bioderived intermediates. the Partner Organisations 2014.
Stereo- and regioselective photocycloaddition of extended alkenes using γ-cyclodextrin
Kashyap, Akshay,Bokosike, Treyvon K.,Bhuvanesh, Nattamai,Pattabiraman, Mahesh
, p. 6870 - 6875 (2018)
Photoexcitation of dibenzalacetones (1a-d) in homogeneous media and solid state yields a mixture of products with poor conversions. Irradiation of the reactants complexed to γ-cyclodextrin predominantly affords a single dimer (syn adduct 6) despite the possibility for several monomeric and dimeric products. High selectivity in the cavitand-mediated reaction along with the structural characterization of the inclusion complex provides insight into the supramolecular interactions that drive the self-assembly of the host-guest system.
Comparative study of physico-chemical properties of laboratory and industrially prepared layered double hydroxides and their behavior in aldol condensation of furfural and acetone
Hora, Luk,Kikhtyanin, Oleg,apek, Libor,Bortnovskiy, Oleg,Kubika, David
, p. 221 - 230 (2014)
In this article, properties of laboratory and industrially prepared Mg-Al layered double hydroxides (LDH) with Mg:Al molar ratios varied in the range from 2 to 4 were compared. Physico-chemical properties of the studied materials were investigated with XR
Study on thermal stabilities and symmetries of chemisorbed species formed on K-zeolites upon CO2 adsorption by TPD and in situ IR spectroscopy
Ganjkhanlou, Yadolah,Bulánek, Roman,Kikhtyanin, Oleg,Frolich, Karel
, p. 355 - 364 (2018)
In the current study, K-zeolites with different structure, Si/Al ratio and morphology have been prepared and then characterized by different techniques including in situ IR spectroscopy upon CO2 sorption and CO2–TPD with the aim of u
Synthesis and characterization of functionalized NaP Zeolite@CoFe2O4 hybrid materials: a micro–meso-structure catalyst for aldol condensation
Mortezaei, Zohreh,Zendehdel, Mojgan,Bodaghifard, Mohammad Ali
, p. 2169 - 2193 (2020)
In this work, magnetic nanocomposite of NaP Zeolite and CoFe2O4 as magnetic nanoparticles (MNP’s) with different ratios were prepared and in the second step functionalized with 2-aminopyridine as a basic group. All samples were characterized by FT-IR, XRD, VSM, FESEM, EDX, TEM, and BET and thermal analyses. The results show that CoFe2O4 MNP’s was dispersed on NaP Zeolite without any significant aggregation with particle size about 30–50?nm. The BET and TEM confirmed the presence of mesoporous phase in the surface of NaP Zeolite/CoFe2O4 and preparation a micro–meso-structure. The NaP Zeolite/CoFe2O4 and NaP Zeolite/CoFe2O4/Am-Py were used as acid–base catalysts for aldol condensation of cyclohexanone with benzaldehyde, and furfural with acetone which produce curcumin and biofuel intermediates, respectively, in solvent-free condition. The effect of different factors such as the percent of CoFe2O4 MNP’s, catalyst amount, solvent, time and temperature was investigated. The catalyst was easily separated with an external magnet and reused four times without significant change in the yield. These catalysts have various advantages including high loading capacity, low leaching for CoFe2O4 MNP’s and simple and efficient recovery procedure which can be used under mild and ecofriendly condition.
Performance of bifunctional Pd/MxNyO (M = Mg, Ca; N = Zr, Al) catalysts for aldolization-hydrogenation of furfural-acetone mixtures
Faba, Laura,Díaz, Eva,Ordó?ez, Salvador
, p. 451 - 456 (2011)
The performance of different bi-functional Pd catalysts (supported on Mg-Zr, Mg-Al and Ca-Zr mixed oxides) for the aqueous-phase aldol-condensation of acetone and furfural was studied in this work. Experiments were carried out in a batch slurry reactor at 323-393 K. Activity trends, as well as selectivity for the formation of the different adducts (C8 and C13), were correlated with the physico-chemical properties of the materials, mainly with the distribution of acid and basic sites. In general, it was observed that the catalyst with the lowest concentration of basic sites (Pd/Ca-Zr) presents the poorest performance. By contrast, the presence of medium-strength acid sites (as the observed in the case of one the Pd/Mg-Al catalyst) seems to enhance the catalytic activity of the material. Although selectivities trends were similar for the catalysts supported on Mg-Zr and Mg-Al catalysts, the ability of the materials for catalyzing the formation of the heaviest adducts depends mainly on the total concentration of basic sites.
Unprecedented selectivities in aldol condensation over Mg-Al hydrotalcite in a fixed bed reactor setup
Kikhtyanin, Oleg,Hora, Luká?,Kubi?ka, David
, p. 89 - 92 (2014)
Aldol condensation of furfural with acetone (molar ratio 1:10) was carried out in a flow fixed bed setup at 50 °C using calcined hydrotalcite with Mg/Al of 3 as a catalyst. Complete conversion of furfural and stable catalyst performance was obtained during the initial 50 h on stream. This period was followed by a rapid catalyst deactivation. In contrast to previous reports, higher molecular weight products that were identified as products of successive aldol condensation of acetone with furfural were observed. Their concentration was time-dependent with a maximum formation after 10 to 30 h on stream.
Toward understanding of the role of Lewis acidity in aldol condensation of acetone and furfural using MOF and zeolite catalysts
Kikhtyanin, Oleg,Kubi?ka, David,?ejka, Ji?í
, p. 158 - 162 (2015)
The aldol condensation of furfural and acetone allow producing higher value products from simple organic compounds resulting from biomass processing. In this paper, a number of metal organic framework (MOF) materials possessing Lewis acidity were investigated as catalysts in this reaction. Experiments were carried out under batch reaction conditions in Parr stirred autoclave at 100 °C during 0-4 h. The catalytic results indicated that the aldol condensation over MOFs took place with the participation of acidic rather than basic centers. The catalytic performance of these materials exhibited could not be explained by their reported Lewis acidity. Experiments with heat-activated and re-hydrated samples showed that Br?nsted acid sites could also be present in MOFs as a consequence of interaction of metal cation with surrounding water molecules. As a consequence, the catalysts having such generated Br?nsted acidity exhibited enhanced activity in the reaction.
Liquid phase aldol condensation reactions with MgO-ZrO2 and shape-selective nitrogen-substituted NaY
Shen, Wenqin,Tompsett, Geoffrey A.,Hammond, Karl D.,Xing, Rong,Dogan, Fulya,Grey, Clare P.,Conner Jr., W. Curtis,Auerbach, Scott M.,Huber, George W.
, p. 57 - 68 (2011)
The aldol condensation reactions of furfural/hydroxymethylfurfural (furfurals) with acetone/propanal in water-methanol solvents were studied over the solid base catalysts MgO-ZrO2, NaY and nitrogen-substituted NaY (Nit-NaY). The reactions were conducted at 120°C and 750 psig of He in batch reactors. Nit-NaY exhibited catalytic activity for aldol condensation comparable to MgO-ZrO2 and much higher than that of NaY, indicative of the increased base strength after replacing the bridging oxygen with the lower electronegativity nitrogen over Nit-NaY. The aldol condensation of furfurals with acetone produces two different products, the monomer and the dimer. The monomer is formed from reaction of furfurals with acetone. The dimer is formed from reaction of the monomer with furfurals. MgO-ZrO2 had a higher selectivity towards dimer formation. In contrast, Nit-NaY was more selective towards the monomer product due to the cage size in the FAU structure, indicating that Nit-NaY is a shape selective base catalyst. Increasing the water concentration in the feed solution or increasing the feed concentration led to both increased catalytic activity and dimer selectivity. The Nit-NaY catalyst was not stable and lost catalytic activity when recycled due to leaching of the framework nitrogen. Different characterization techniques, including XRD, high resolution Ar adsorption isotherm, basic sites titration, CO2 TPD-MS, TGA and 29Si SP MAS NMR, were used here to characterize the fresh and spent catalysts. The results show that Nit-NaY maintains only part of the FAU-type crystal structure. Furthermore, the base strength over Nit-NaY was found to be between that of Mg2+-O 2- pair and Mg(OH)2. The reaction mechanism over Nit-NaY was discussed.
Synthesis of jet fuel intermediates via aldol condensation of biomass-derived furfural with lanthanide catalyst
Cong, Wen-Jie,Fang, Zhen,Kong, Xiao,Li, Lu-ping
, (2021/10/01)
Jet fuel precursors (4-(2-furyl)-3-buten-2-one (FAc) and 1,5-di-2-furanyl-1,4-pentadien-3-one (F2Ac)) can be produced from aldol condensation between furfural and acetone over basic catalysts. However, there is still a need to develop efficient alkaline catalysts and understand the role of alkaline sites. In this work, La2O2CO3-Al2O3 catalyst was successfully prepared by coprecipitation and the effect of preparation conditions on the properties and catalytic performance was investigated. Experiments showed that La2O2CO3 and La2O3 were formed after calcination, and the activity was greatly improved by the introduction of La2O2CO3. At higher coprecipitation pH, rod-shaped La2O2CO3 was formed, which exhibits higher exposure of basic La3+-O2? sites and shows good performance in aldol condensation reactions. The catalytic performance of La2O2CO3-Al2O3 in aldol condensation of furfural with acetone was also evaluated and compared with that of Al2O3, La2O3, La2O3-Al2O3, La(OH)?/Al2O3 and La2O2CO3/Al2O3. A total conversion of furfural can be realized with F2Ac yield of 67.8% at a furfural/acetone ratio of 1/1 and 90 °C, with a FAc yield of 25.8% at the same time. The deactivation mechanism of the La2O2CO3-Al2O3 catalyst was also studied.
