- Surface dynamics of a vanadyl pyrophosphate catalyst for n-butane oxidation to maleic anhydride: An in situ Raman and reactivity study of the effect of the P/V atomic ratio
-
This work focused on investigating the effect of the P/V atomic ratio in vanadyl pyrophosphate, catalyst for n-butane oxidation to maleic anhydride, on the nature of the catalytically active phase. Structural transformations occurring on the catalyst surface were investigated by means of in situ Raman spectroscopy in a non-reactive atmosphere, as well as by means of steady-state and non-steady-state reactivity tests, in response to changes in the reaction temperature. It was found that the nature of the catalyst surface is affected by the P/V atomic ratio even in the case of small changes in this parameter. With the catalyst having P/V equal to the stoichiometric value, a surface layer made of α-VOPO4 developed in the temperature interval 340400°C in the presence of air; this catalyst gave a very low selectivity to maleic anhydride in the intermediate T range (340-400°C). However, at 400440°C δ-VOPO4 overlayers formed; at these conditions, the catalyst was moderately active but selective to maleic anhydride. With the catalyst containing a slight excess of P, the ratio offering the optimal catalytic performance, δVOPO4 was the prevailing species over the entire temperature range investigated (340-440°C). Analogies and differences between the two samples were also confirmed by reactivity tests carried out after in situ removal and reintegration of P. These facts explain why the industrial catalyst for n-butane oxidation holds a slight excess of P; they also explain discrepancies registered in the literature about the nature of the active layer in vanadyl pyrophosphate.
- Cavani, Fabrizio,Luciani, Silvia,Esposti, Elisa Degli,Cortelli, Carlotta,Leanza, Roberto
-
-
Read Online
- Structure Sensitivity of the Catalytic Oxidation of n-Butane to Maleic Anhydride
-
Disorder along the (020) cleavage plane of the (VO)2P2O7 catalyst considerably enhances the activity of the selective oxidation of n-butane to maleic anhydride.
- Cavani, Fabrizio,Centi, Gabriele,Trifiro, Ferruccio
-
-
Read Online
- ΑII-(V1-xWx)OPO4 catalysts for the selective oxidation of n-butane to maleic anhydride
-
The vanadyl pyrophosphate (VPP) based catalyst is unique in converting n-butane selectively (60–70%) into maleic anhydride (MAN), whereas a MAN selectivity of 20% may be regarded as high for structurally different catalyst systems. We present novel vanadium phosphorus oxides and mixed metal phosphate solid solutions tested for n-butane oxidation to MAN with a selectivity of >30%. The majority of the catalysts were prepared by solution combustion synthesis. (V1-xWx)OPO4 with αII structure was found to be more active and selective in the oxidation of n-butane compared to β-VOPO4. By adjusting the tungsten content the oxidation state of vanadium in (V1-xWx)OPO4 can be tuned between 4.74 and 4.99, which is regarded as a key factor for MAN production. All catalysts were structurally stable, but the specific surface area increased during the reaction, as detected by X-ray diffraction and N2 physisorption, respectively. (V1-xMox)OPO4 was also stable, but the MAN selectivity was lower compared to β-VOPO4. Low conversions result from the low surface area of the screening samples, however, could be overcome by advanced synthesis protocols.
- Schulz,Roy,Wittich,d'Alnoncourt, R. Naumann,Linke,Strempel,Frank,Glaum,Rosowski
-
-
Read Online
- In Situ FTIR Spectroscopy of 1-Butene and 1,3-Butadiene Selective Oxidation to Maleic Anhydride on V-P-O Catalysts
-
The selective oxidation of 1-butene and 1,3-butadiene was studied by transmission infrared spectroscopy.Vanadium-phosphorous-oxygen catalysts prepared by the reaction of V2O5 with H3PO4 in alcohol solution were used.Infrared spectra were collected in situ during the flow of 75 cm3 of 1.5percent hydrocarbon-in-air mixtures over catalysts having P-to-V ratios of 0.9, 1.0, and 1.1.Reaction temperatures from 300 to 400 deg C were investigated with 1-butene feeds, whereas the highly reactive 1,3-butadiene was studied only at 300 deg C.An adsorbed butadiene species, maleic acid, maleic anhydride were observed during both olefin partial oxidation studies.Evidence was obtained for a second olefin species which had been previously observed for in situ n-butane selective oxidation studies.Concentrations of adsorbed species were found to vary with catalyst phosphorous loading, reaction temperature, and time of exposure to reaction conditions.
- Wenig, Robert W.,Schrader, Glenn L.
-
-
Read Online
- Activity and Selectivity in Catalytic Reactions of Buta-1,3-diene and But-1-ene on Supported Vanadium Oxides
-
The activity and selectivity in the oxidation of buta-1,3-diene, and oxidation and isomerization of but-1-ene on unsupported and supported V2O5 catalysts have been investigated in terms of the catalyst structure.The rate of oxidation is mainly determined by the number of surface V=O species on the catalyst for both buta-1,3-diene and but-1-ene.The roughness of the V2O5 surface affected the activity for buta-1,3-diene, but not for but-1-ene oxidation.It was also found that TiO2 support increases the activity of the surface V=O for but-1-ene oxidation.The selectivity to maleic anhydride was determined by the number of V2O5 layers on the support for both reactions.When the number of V2O5 layers was 1 or 2, the selectivity was low, while it increased markedly with an increase in the number of V2O5 layers to 5, and attained a constant value above 5 layers.Both V2O5 and support were active for the isomerization of but-1-ene to cis- and trans-but-2-ene.On V2O5, the cis/trans ratio was low, while it was as high as 3 for the Al2O3 support.The rate and selectivity of the isomerization on supported catalysts were explained in terms of the structure of V2O5 on the support.Difference in the structure-activity/selectivity correlation between oxidation and isomerization and that between but-1-ene oxidation and buta-1,3-diene oxidation were also discussed.
- Mori, Kenji,Miyamoto, Akira,Murakami, Yuichi
-
-
Read Online
- Effects of cobalt additive on amorphous vanadium phosphate catalysts prepared using precipitation with supercritical co2 as an antisolvent
-
The effect of addition of cobalt to an amorphous vanadium phosphate for the selective oxidation of n-butane to maleic anhydride is described and discussed. Cobalt is a well known promoter for crystalline vanadium phosphate catalysts and is most effective at a concentration of 1 atom % relative to vanadium. In contrast, for amorphous vanadium phosphate materials, prepared by precipitation using supercritical CO2 as an antisolvent, cobalt appears to act as a catalyst poison, decreasing both the catalyst activity and selectivity for maleic anhydride. Detailed analysis by transmission electron microscopy, 31P spin echo mapping NMR spectroscopy and X-ray absorption spectroscopy is described, which highlight differences with the unmodified catalyst. It is concluded that the addition of cobalt affects the morphology of the material and the oxidation state of vanadium, and that these changes deleteriously affect the catalytic performance.
- Lopez-Sanchez, J. Antonio,Bartley, Jonathan K.,Burrows, Andrew,Kiely, Christopher J.,Haevecker, Michael,Schloegl, Robert,Volta, Jean Claude,Poliakoff, Martin,Hutchings, Graham J.
-
-
Read Online
- Surface Acidity of Vanadyl Pyrophosphate, Active Phase in n-Butane Selective Oxidation
-
The surface acidity of two (VO)2P2O7catalysts with similar specific activities per square meter of surface area in 1-butene selective oxidation, but different specific activities in n-butane selective oxidation, was studied by ammonia, pyridine, acetonitrile, CO, and CO2 adsorption, by ammonia temperature-programmed desorption, and by 2-propanol oxidation.The results for both catalysts indicate the presence of strong Broensted sites attributed to surface P-OH groups and of medium strong Lewis sites attributed to V(IV) coordinatively unsaturated ions exposed on the surface.The presence of these centers was related to the (VO)2P2O7 structure itself and is fairly independent of the (VO)2P2O7 preparation method.However, in the (VO)2P2O7 prepared in an organic medium and to a lesser extent in the (VO)2P2O7 prepared in an aqueous medium, the presence of very strong Lewis sites also was observed.The enhancement of the rate of n-butane activation in the (VO)2P2O7 prepared in an organic medium was attributed to the presence of these sites.The role of the preparation method in the formation of such very strong Lewis sites also is discussed.
- Busca, Guido,Centi, Gabriele,Trifiro, Ferruccio,Lorenzelli, Vincenzo
-
-
Read Online
- Preparation and characterization of vanadyl hydrogen phosphate hydrates; VO(HPO4)*1.5 H2O and VO(HPO4)*0.5 H2O
-
A new phase of vanadyl(IV) hydrogen phosphate sesquihydrate, VO(HPO4)*1.5 H2O, has been obtained by the reduction of VOPO4*2H2O with 1-butanol.The unit cell is the orthorhombic system with lattice constants a=7.43 Angstroem, b=9.62 Angstroem, and c=7.97 Angstroem in space group Pmmn.
- Matsuura, Ikuya,Ishimura, Tomohiro,Kimura, Naomasa
-
-
Read Online
- X-Ray Study of a Vanadium-Phosphorus Mixed Oxide Catalyst for Selective Butane Oxidation to Maleic Anhydride
-
The radical electron distribution obtained from X-ray patterns has been used to study the structure of a poorly-crystalline vanadium-phosphorus mixed oxide (VPO) catalyst after selective oxidation of n-butane; the effective catalyst consists of a mixture of a crystallized (VO)2P2O7 phase (V(4+)) and an amorphorus VPO phase (V(5+)) showing many corner-sharing VO6 octahedra.
- Bergeret, G.,Broyer, J. P.,David, M.,Gallezot, P.,Volta, J. C.,Hecquet, G.
-
-
Read Online
- Effects of Consecutive Oxidation on the Production of Maleic Anhydride in Butane Oxidation over Four Kinds of Well-Characterized Vanadyl Pyrophosphates
-
Factors determining the selectivity of butane oxidation at high conversion levels have been examined by using four kinds of well-characterized vanadyl pyrophosphate catalysts (C-1 - C-4) in kinetic experiments.The catalysts were carefully characterized by scanning electron microscopy, X-ray powder diffraction, X-ray photoelectron spectroscopy, and infrared spectroscopy and were made of a single crystalline phase of vanadyl pyrophosphate, (VO)2P2O7.C-1 was prepared by reduction with NH2OH*HCl and consisted of large particles (5 μm) and small particles (0.2 μm).The particles of C-2 obtained from V2O4 had a size of 2 μm.C-3, which was obtained by an organic solvent method, showed a rose-like structure.C-4 from VOPO4*2H2O had a large plate-like structure (5 μm).While all of the catalysts exhibited similar selectivities for the formation of maleic anhydride (63-72 percent) at low conversion levels, the extend of selecticity decreases with an increase in the conversion and strongly depends on the catalysts.It also correlates oppositely with the catalytic activity for the oxidation of maleic anhydride, measured separately.This indicates that the consecutive oxidation of product maleic anhydride is a crucial factor for the selectivity at high conversions.A simulation using a model that includes the consecutive oxidation of maleic anhydride, in which the experimental rate constants for the oxidation of butane and maleic anhydride have been used, reproduced the selectivity-conversion curves experimentally observed.
- Igarashi, Hiroshi,Tsuji, Katsuyuki,Okuhara, Toshio,Misono, Makoto
-
-
Read Online
- Diels-Alder reaction of vinylene carbonate and 2,5-dimethylfuran: Kinetic vs. thermodynamic control
-
The Diels - Alder reaction between 2,5-dimethylfuran and vinylene carbonate was studied, both from an experimental and a theoretical point of view. The system was shown to slowly reach a thermodynamic equilibrium, characterized by the almost exclusive formation of the exo isomer. We rationalized these results by a comparison with classical systems involving maleic anhydride, and highlighted the different reactivity of vinylene carbonate as a dienophile. Finally, a preparative scale synthesis of pure exo isomer 4, a potentially useful synthon, ensued from this work. The Royal Society of Chemistry and the Centre National de la Recherche Scientifique 2010.
- Taffn, Celine,Kreutler, Glenda,Bourgeois, Damien,Clot, Eric,Perigaud, Christian
-
-
Read Online
- Fundamental studies of butane oxidation over model-supported vanadium oxide catalysts: Molecular structure-reactivity relationships
-
The oxidation of n-butane to maleic anhydride was investigated over a series of model-supported vanadia catalysts where the vanadia phase was present as a two-dimensional metal oxide overlayer on the different oxide supports (TiO2, ZrO2, CeO2, Nb2O5, Al2O3, and SiO2). No correlation was found between the properties of the terminal V=O bond and the butane oxidation turnover frequency (TOF) during in situ Raman spectroscopy study. Furthermore, neither the n-butane oxidation TOF nor maleic anhydride selectivity was related to the extent of reduction of the surface vanadia species. The n-butane oxidation TOF was essentially independent of the surface vanadia coverage, suggesting that the n-butane activation requires only one surface vanadia site. The maleic anhydride TOF, however, increased by a factor of 2-3 as the surface vanadia coverage was increased to monolayer coverage. The higher maleic anhydride TOF at near monolayer coverages suggests that a pair of adjacent vanadia sites may efficiently oxidize n-butane to maleic anhydride, but other factors may also play a contributing role (increase in surface Bronsted acidity and decrease in the number of exposed support cation sites). Varying the specific oxide support changed the n-butane oxidation TOF by ca. 50 (Ti > Ce > Zr ～ Nb > Al > Si) as well as the maleic anhydride selectivity. The maleic anhydride selectivity closely followed the Lewis acid strength of the oxide support cations, Al > Nb > Ti > Si > Zr > Ce. The addition of acidic surface metal oxides (W, Nb, and P) to the surface vanadia layer was found to have a beneficial effect on the n-butane oxidation TOF and the maleic anhydride selectivity. The creation of bridging V-O-P bonds had an especially positive effect on the maleic anhydride selectivity.
- Wachs, Israel E.,Jehng, Jih-Mirn,Deo, Goutam,Weckhuysen, Bert M.,Guliants,Benziger,Sundaresan
-
-
Read Online
- Ionization and Intramolecular Reactions of N,N-Bis- and N,N-Bismaleamic Acids. An Enzyme Model
-
N,N-Bismaleamic acid (1) and N,N-bismaleamic acid (2) underwent exclusive amide hydrolysis and intramolecular Michael-type addition, respectively.The pH profile of the pseudo-first-order rate constant for the reaction of 1 was a simple descending sigmoid inflecting at the pKa of the carboxyl group.The pH profile of 2 was a composite of two bell-shaped curves which disclosed the abnormally low pKa's of the carboxyl group and one of the two pyridinium groups.The change in the reaction path and the abnormal pKa's observed withthe structural variation in maleamic acid derivatives suggest that the change in enzyme specificity and the perturbed pKa's of the active site functional groups can be achieved with a relatively loose geometry of the enzyme-substrate complex.The failure to observe the metal ion catalysis of the amide hydrolysis of 1 and 2 indicates that the metal complexation of the compounds is inefficient.
- Suh, Junghun,Kim, Mahn Joo,Seong, Nak Jin
-
-
Read Online
- Selective aerobic oxidation of furfural to maleic anhydride with heterogeneous Mo-V-O catalysts
-
A heterogeneous catalytic system using binary Mo-V metal oxides as catalysts was demonstrated for the selective aerobic oxidation of furfural to maleic anhydride (MA). Aspects such as the solvent for the reaction, the phase composition and the Mo/V ratio for the catalyst, and other reaction conditions were investigated in detail. Up to 65% yield of MA was achieved over the Mo4VO14 catalyst in an acetic acid solvent under optimal conditions. The catalyst could be recycled. The reaction mechanism and the role of the acetic acid solvent were also discussed.
- Li, Xiukai,Ho, Ben,Zhang, Yugen
-
-
Read Online
- Significant catalytic recovery of spent industrial DuPont catalysts by surface deposition of an amorphous vanadium-phosphorus oxide phase
-
DuPont's vanadium phosphorous oxide catalyst (VPO) deactivated with time-on-stream in a commercial butane to maleic anhydride reactor. Coincidentally, V5+ phases formed on the surface (based on XPS)-principally β-VOPO4 but also V2O5. This catalyst was reactivated by introducing a small amount of a VPO (theoretical P/V atomic ratio = 0.86) phase. The maleic anhydride production rate of the reactivated catalyst was higher by about 60% compared to the used catalyst. n-Butane conversion increased by about 50% and the selectivity to maleic anhydride improved by 15%. The analyses of the modified catalyst by X-ray diffraction, Raman spectroscopy and X-ray photoelectron spectroscopy showed that the V2O5 and β-VOPO4 phases disappeared and suggested that an amorphous phase formed on the surface. The treatment resulted in a lower V5+/V4+ and P/V ratios on the used catalyst surface.
- Blanco, Raquel Mateos,Shekari, Ali,Carrazán, Silvia González,Bordes-Richard, Elisabeth,Patience, Gregory S.,Ruiz, Patricio
-
-
Read Online
- Selectivity and Activity in the Oxidation of Benzene, 1-Butene, and 1,3-Butadiene on Supported Vanadium Oxide Catalysts
-
Selectivity with respect to partial oxidation products in the oxidation of benzene, 1-butene, and 1,3-butadiene on V2O5/TiO2 and V2O5/Al2O3 catalysts is determined by the number of V2O5 layers on the support, while the activity is controlled by the number of surface V=O species on the catalyst.
- Mori, Kenji,Inomata, Makoto,Miyamoto, Akira,Murakami, Yuichi
-
-
Read Online
- Synthesis of vanadium phosphorus oxide catalysts promoted by iron-based ionic liquids and their catalytic performance in selective oxidation of: n -butane
-
A series of vanadium phosphorus oxide (VPO) catalysts have been firstly synthesized using iron-based ionic liquids (ILs) as additives for selective oxidation of n-butane to maleic anhydride (MA) in this work. Meanwhile, VPO catalysts doped with inorganic iron salts were also prepared for comparison. The catalytic evaluation presented that iron-based IL modification remarkably enhanced the n-butane conversion and MA yield. A combination of techniques including XRD, Raman, TG, BET, SEM, TEM, XPS and H2-TPR was employed to investigate the intrinsic distinction among these catalysts. The results demonstrated that iron-based ILs notably change the morphology of the VPO catalyst from a plate-like structure into chrysanthemum-shape clusters, leading to a significant increase in the surface area of the catalyst, and largely promote the formation of (VO)2P2O7. All of these were closely associated with the synergistic effect existing between the structure-oriented cations and metal anions in ILs during the preparation of the VPO catalyst. In addition, the differences in the structure and redox properties of the catalysts studied were also discussed and compared with those doped with conventional inorganic salt additives.
- Dai, Fei,Li, Zihang,Chen, Xuejing,He, Bin,Liu, Ruixia,Zhang, Suojiang
-
-
Read Online
- Comparison of pH-sensitive degradability of maleic acid amide derivatives
-
We synthesized five maleic acid amide derivatives (maleic, citraconic, cis-aconitic, 2-(2′-carboxyethyl) maleic, 1-methyl-2-(2′- carboxyethyl) maleic acid amide), and compared their degradability for the future development of pH-sensitive biomaterials with tailored kinetics of the release of drugs, the change of charge density, and the degradation of scaffolds. The degradation kinetics was highly dependent upon the substituents on the cis-double bond. Among the maleic acid amide derivatives, 2-(2′-carboxyethyl) maleic acid amide with one carboxyethyl and one hydrogen substituent showed appropriate degradability at weakly acidic pH, and the additional carboxyl group can be used as a pH-sensitive linker.
- Kang, Sunyoung,Kim, Youngeun,Song, Youngjun,Choi, Jin Uk,Park, Euddeum,Choi, Wonmin,Park, Jeongseon,Lee, Yan
-
-
Read Online
- The conversion of 5-hydroxymethyl furfural (HMF) to maleic anhydride with vanadium-based heterogeneous catalysts
-
Heterogeneous catalytic systems using vanadium-based solid catalysts with or without silica support were developed for the oxidation of 5-hydroxymethyl furfural (HMF) to maleic anhydride (MA) and up to 79% yield of MA was achieved. Both unsupported and silica supported vanadium oxide catalysts showed high activity, selectivity, and recyclability. The direct conversion of fructose to MA via the HMF intermediate was further demonstrated and over 50% overall yield of MA was achieved.
- Li, Xiukai,Zhang, Yugen
-
-
Read Online
- Effect of direct ultrasound synthesis via a sesquihydrate route on bismuth-promoted vanadyl pyrophosphate catalysts
-
A series of 1, 3, and 5% Bi-doped vanadium phosphate catalyst catalysts were prepared via sesquihydrate route using direct ultrasound method and were denoted as VPSB1, VPSB3, and VPSB5, respectively. These catalysts were synthesized solely using a direct ultrasound technique and calcined in a n-butane/air mixture. This study showed that catalyst synthesis time can be drastically reduced to only 2 hr compared to conventional 32–48 hr. All Bi-doped catalysts exhibited a well-crystallized (VO)2P2O7 phase. In addition, two V5+ phases, that is, β-VOPO4 and αII-VOPO4, were observed leading to an increase in the average oxidation state of vanadium. All catalysts showed V2p3/2 at approx. 517 eV, giving the vanadium oxidation state at approx. 4.3–4.6. Field-emission scanning electron microscopy micrographs showed the secondary structure consisting of thin and small plate-like crystal clusters due to the cavitation effect of ultrasound waves. VPSB5 showed the highest amount of oxygen species removed associated with the V5+ and V4+ species in temperature-programmed reduction in H2 analyses. TheX-ray absorption near edge structure (XANES) measurement showed the occurrence of vanadium oxide reductions in hydrogen gas flow, indicating the presence of V4+ and V5+ species. Higher average valence states of V5+, indicating more V5+ phases, were present. The addition of bismuth has increased the activity and selectivity to maleic anhydride.
- Goo, Kang-Zhi,Yap, Yeow-Hong,Lin, Kuen-Song,Leong, Loong-Kong
-
-
Read Online
- Spectroscopic Investigation of Vanadium-Phosphorus Catalysts
-
The structural and surface changes occurring in vanadium-phosphorus mixed oxides with P/V atomic ratios in the 1.0 - 1.8 range prepared by reducing the V(V) with oxalic acid were investigated by ESR, diffuse reflectance spectroscopy, X-ray diffraction, and redox titrimetry.Poorly crystallized α-VOPO4 was formed for a P/V ratio of 1.0, and new phases containing V(IV) were found as the P/V ratio increased.The V(IV) centers changed progressively from isolated, dispersed ions in a α-VOPO4 matrix into a V(IV) phosphate phase, as revealed by ESR and diffuse reflectance spectra.These results are compared with catalytic activity data for the 1-butene oxidation in a pulse reactor.The highest yield of maleic anhydride was given by the samples with a 1.0 - 1.2 P/V ratio, indicating that VOPO4 with dispersed V(IV) ions is the active phase.
- Martini, Giacomo,Trifiro, Ferruccio,Vaccari, Angelo
-
-
Read Online
- Towards physical descriptors of active and selective catalysts for the oxidation of n-butane to maleic anhydride
-
Based on our newly developed microwave cavity perturbation technique, the microwave conductivity of diverse vanadium(III), (IV), and (V) phosphate catalysts was measured under reaction conditions for the selective oxidation of n-butane. The conductivity response on the gas phase was identified as a very sensitive measure for the redox kinetics, reversibility, and stability of the samples, which are important prerequisites for highly selective and active catalysts. The sensitivity achieved by our method was comparable to surface-sensitive methods such as X-ray photoelectron spectroscopy, whereas more conventional analytic techniques such as X-ray diffractometry or Raman spectroscopy only indicated the stability of the bulk crystal phase under the same reaction conditions.
- Eichelbaum, Maik,Glaum, Robert,Haevecker, Michael,Wittich, Knut,Heine, Christian,Schwarz, Heiner,Dobner, Cornelia-Katharina,Welker-Nieuwoudt, Cathrin,Trunschke, Annette,Schloegl, Robert
-
-
Read Online
- Influence of starting solution in preparation of V2O5/TiO2 catalysts for selective oxidation of benzene
-
The selectivity in benzene oxidation over V2O5/TiO2(rutile) was drastically changed with starting solutions in the preparation of catalysts, although V2O5/TiO2(rutile) prepared from oxalic acid solution of NH4VO3 selectively oxidized benzene to maleic anhydride, only a total oxidation proceeded over those prepared without oxalic acid.
- Satsuma, Atsushi,Takenaka, Sakae,Tanaka, Tsunehiro,Nojima, Shigeru,Kera, Yoshiya,Miyata, Hisashi
-
-
Read Online
- Surface Dynamics of Adsorbed Species on Heterogeneous Oxidation Catalysts: Evidence from the Oxidation of C4 and C5 Alkanes on Vanadyl Pyrophosphate
-
Steady-state and transient reactivity measurements, Fourier-transform infrared studies, and stopped-flow desorption analyses of the selective oxidation of C4 and C5 alkanes at the vanadyl pyrophosphate surface suggest that the surface dynamics of adsorbed species plays an important role in determining the selective oxidation pathways and the nature of the products of selective oxidation.The results indicate the possibility of two different oxidation pathways in maleic anhydride synthesis from n-butane which involve the intermediate formation of either a lactone or furan and which are characterized by different rates and selectivities.The presence of side methyl groups in the formation of similar intermediates from n-pentane decreases their reactivity and favors a parallel surface reaction between intermediates with the final formation of phthalic anhydride from the C5 hydrocarbon.However, when the rate of conversion of the intermediates is increased, thus modifying the surface availability of oxygen, maleic anhydride also becomes the principal product from the C5 alkane.
- Busca, Guido,Centi, Gabriele
-
-
Read Online
- A good performance VPO catalyst for partial oxidation of n-Butane to maleic anhydride
-
A VPO catalyst prepared by the reaction of vanadium pentoxide and isobutyl alcohol/benzyl alcohol in the presence of polyethylene glycol with the molecular weight of 2000 (PEG2000) was found to be highly selective and active for the conversion of n-butane to maleic anhydride.
- Wang, Xiaoshu,Nie, Weiyan,Ji, Weijie,Guo, Xuefeng,Yan, Qijie,Chen, Yi
-
-
Read Online
- Catalytic Synthesis of 2,5-Furandicarboxylic Acid from Concentrated 2,5-Diformylfuran Mediated by N-hydroxyimides under Mild Conditions
-
Producing polyester monomer 2,5-furandicarboxylic acid (FDCA) from biomass as an alternative to fossil-derived terephthalic acid has drawn much attention from both academy and industry. In this work, an efficient FDCA synthesis was proposed from 10.6 wt % 2,5-diformylfuran (DFF) in acetic acid using a combined catalytic system of Co/Mn acetate and N-hydroxyimides. The intermediate product of 5-formyl-2-furandicarboxylic acid (FFCA) possesses the least reactive formyl group. N-hydroxysuccinimide was found to be superior to N-hydroxyphthalimide in catalyzing the oxidation of the formyl group in FFCA intermediate, affording a near 95 % yield of FDCA under mild conditions of 100 °C. Trace maleic anhydride was detected as by-product, which mainly came from the oxidative cleavage of DFF via furfural, furoic acid and 5-acetoxyl-2(5H)-furanone as intermediates.
- Xia, Fei,Ma, Jiping,Jia, Xiuquan,Guo, Meiling,Liu, Xuebin,Ma, Hong,Gao, Jin,Xu, Jie
-
-
Read Online
- On the Role of the VO(H2PO4)2 Precursor for n-Butane Oxidation into Maleic Anhydride
-
The catalytic role of VO(H2PO4)2, the precursor of the V O(PO3)2 phase, has been studied for n-butane oxidation to maleic anhydride.By comparison with the activated VPO catalyst, derived from the VOHPO4*0.5H2O precursor phase, VO(H2PO4)2 gives a highly selective final catalyst.The total oxidation products CO and CO2 are not observed under any of the conditions examined, a result confirmed by extensive catalyst testing and carbon mass balances.The final catalyst derived from VO(H2PO4)2 has a low surface area, ca. 1 m2/g, and consequently demonstrates low specific activity on the basis of n-butane conversion per unit mass.However, the interinsic activity (activity per unit surface area) is found to be higher than that for catalysts derived from VOHPO4 * 0.5H2O.Since some VO(H2PO4)2 is present in VOHPO4 * 0.5H2O, which is the precursor of the industrial catalyst, the results of this study complicate the simple model in which the (VO)2P2O7 phase derived from VOHPO4 * 0.5H2O is responsible for the selective oxidation of n-butane.The observation that the precursor VO(H2PO4)2 can generate catalysts of high specific activity and of total selectivity to partial oxidation products might provide a useful insight into the design of a new series of high activity and high selectivity partial oxidation catalysts.
- Sananes, M. T.,Hutchings, G. J.,Volta, J. C.
-
-
Read Online
- The consequences of support identity on the oxidative conversion of furfural to maleic anhydride on vanadia catalysts
-
Maleic anhydride (MA) is a high value building block molecule whose synthesis from furfural (FUR) is proposed as a green and sustainable alternative. In this work, vanadia supported on SiO2, γ-Al2O3, ZrO2 and TiO2 catalysts were synthetized, characterized and investigated for the selective gas phase oxidation of FUR to MA. The catalytic properties depend on both, the nature of the support and the vanadia surface dispersion. V2O5/SiO2 and V2O5/γ-Al2O3 display ca. 50 % MA yield. Conversely, for the V2O5/ZrO2 and V2O5/TiO2 catalysts, complete FUR oxidation to CO2 and negligible MA production was obtained. By decreasing the oxidation potential of the reaction feed, V2O5/ZrO2 and V2O5/TiO2 catalysts achieve MA yields comparable to V2O5/SiO2 and V2O5/γ-Al2O3 catalysts. This behavior is attributed to the higher vanadia dispersion on ZrO2 and TiO2 and the reducible nature of these supports. The results obtained in this work offer new catalytic alternatives for the sustainable production of MA.
- Santander, Paola,Bravo, Luis,Pecchi, Gina,Karelovic, Alejandro
-
-
Read Online
- Vanadium-oxo immobilized onto Schiff base modified graphene oxide for efficient catalytic oxidation of 5-hydroxymethylfurfural and furfural into maleic anhydride
-
Graphene oxide (GO) sheets are emerging as a new class of carbocatalyst, and also a perfect platform for molecular engineering. The hydroxyl groups on either side of GO sheets can function as anchors by employing them as scaffolds linking organometallic nodes and vanadium-oxo was homogeneously immobilized on a Schiff base modified GO support via covalent bonding. The developed VO-NH2-GO was shown to be an efficient and recyclable heterogeneous catalyst for the aerobic oxidation of 5-hydroxymethylfurfural (HMF) into maleic anhydride. Up to 95.3% yield of maleic anhydride from HMF and 62.4% from furfural were achieved under optimized reaction conditions. The immobilized vanadium oxo was identified as the active sites, while the residual oxygen-containing groups worked synergistically to adsorb HMF to maintain a high reactant concentration around the catalyst. The STY value was enhanced significantly over VO-NH2-GO, compared with homogeneous or heterogeneous traditional supported V based catalyst.
- Lv, Guangqiang,Chen, Chunyan,Lu, Boqiong,Li, Jinlong,Yang, Yongxing,Chen, Chengmeng,Deng, Tiansheng,Zhu, Yulei,Hou, Xianglin
-
p. 101277 - 101282
(2016)
-
Read Online
- Kinetic and structural understanding of bulk and supported vanadium-based catalysts for furfural oxidation to maleic anhydride
-
The kinetics of gas-phase furfural partial oxidation to maleic anhydride (MA) was studied over bulk vanadium-phosphorus-based catalysts obtained by aqueous (VPAq) and organic (VPOr) methods and compared to a supported V2O5/Al2O3 catalyst. The solids were characterized by N2 adsorption-desorption, XRD and UV-vis DRS. Results showed a higher specific surface area on VPOr compared with VPAq materials, with a well-defined (VO)2P2O7 crystalline structure. UV-vis analysis showed mainly V(v) on VPAq and an intermediate state between V(iv) and V(v) on VPOr. A detailed kinetic study demonstrated that furfural can be oxidized to MA or COx through parallel paths. At high oxygen partial pressures MA oxidation is inhibited on VPO catalysts but favored on V2O5/Al2O3. A Langmuir-Hinshelwood kinetic model with negligible site occupancy fits the experimental data with a 16% mean error. It also shows a higher apparent activation energy for furfural partial oxidation than for complete oxidation, highlighting the favored selectivity to maleic anhydride at higher temperatures on VPO catalysts.
- Bravo, Luis,Gómez-Cápiro, Oscar,Karelovic, Alejandro,Lagos, Patricio,Pecchi, Gina,Santander, Paola
-
-
Read Online
- The electronic factor in alkane oxidation catalysis
-
This article addresses the fundamental question of whether concepts from semiconductor physics can be applied to describe the working mode of heterogeneous oxidation catalysts and whether they can be even used to discriminate between selective and unselective reaction pathways. Near-ambient-pressure X-ray photoelectron spectroscopy was applied to the oxidation of n-butane to maleic anhydride on the highly selective catalyst vanadyl pyrophosphate and the moderately selective MoVTeNbOx M1 phase. The catalysts were found to act like semiconducting gas sensors with a dynamic charge transfer between the bulk and the surface, as indicated by the gas-phase-dependent response of the work function, electron affinity, and the surface potential barrier. In contrast, only a minor influence of the gas phase on the semiconducting properties and hence no dynamic surface potential barrier was monitored for the total oxidation catalyst V2O5. The surface potential barrier is hence suggested as descriptor for selective catalysts.
- Eichelbaum, Maik,H?vecker, Michael,Heine, Christian,Wernbacher, Anna Maria,Trunschke, Annette,Schl?gl, Robert,Rosowski, Frank
-
-
Read Online
- Hydroxyapatite-Supported Polyoxometalates for the Highly Selective Aerobic Oxidation of 5-Hydroxymethylfurfural or Glucose to 2,5-Diformylfuran under Atmospheric Pressure
-
(NH4)5H6PV8Mo4O40 supported on hydroxyapatite (HAP) (PMo4V8/HAP (n)) was prepared through the ion exchange of hydroxy groups. This ion exchange favored the oxidative conversion of 5-hydroxymethylfurfural (5-HMF) to 2,5-diformylfuran (DFF) in a one-pot cascade reaction with 96.0 % conversion and 83.8 % yield under 10 mL/min of O2 flow. PMo4V8/HAP (31) was used to explore the production of DFF directly from glucose with the highest yield of 47.9 % so far under atmospheric oxygen, whereas the yield of DFF increased to 54.7 % in a one-pot and two-step reaction. These results indicated that the active sites in PMo4V8/HAP (31) retained their activities without any interference toward one another, which enabled the production of DFF in a more cost-saving way by only using oxygen and one catalyst in a one-step reaction. Meanwhile, the rigid structure of HAP and strong interaction in PMo4V8/HAP (31) allowed this catalyst to be reused for at least six times with high stability and duration.
- Guan, Hongyu,Li, Ying,Wang, Qiwen,Wang, Xiaohong,Yu, Hang
-
-
Read Online
- Oxidation of levulinic acid for the production of maleic anhydride: breathing new life into biochemicals
-
Levulinic acid (LA) is a biomass-derived platform chemical that could play a central role in emerging industries as an intermediate that facilitates production of bio-based commodities. In this context, we present a novel, catalytic pathway for the synthesis of maleic anhydride (MA) via oxidative cleavage of the methyl carbon in LA over supported vanadates. The approach is demonstrated in a continuous flow, packed bed reactor, and we have observed that VOx supported on SiO2 achieves single-pass MA yields as high as 71%. Preliminary analysis suggests that LA might compete with butane as an industrial MA feedstock. Finally, bifunctional LA and monofunctional 2-pentanone display contrasting oxidative cleavage selectivities, indicating that methyl carbon cleavage during vapor phase oxidation over supported vanadates is unique to LA.
- Chatzidimitriou, Anargyros,Bond, Jesse Q.
-
-
Read Online
- Catalytic aerobic oxidation of renewable furfural to maleic anhydride and furanone derivatives with their mechanistic studies
-
Catalytic transformation of biomass-based furfural to value-added chemicals is an alternative route to the on-going fossil feedstock-based processes. This work describes catalytic aerobic oxidation of furfural to maleic anhydride, an important polymer starting material having a large market with H 5PV2Mo10O40 and Cu(CF 3SO3)2 catalysts. Under the optimized conditions, 54.0% yield of maleic anhydride can be achieved with about 7.5% yield of 5-acetoxyl-2(5H)-furanone formation. Notably, 5-acetoxyl-2(5H)-furanone is a highly value-added, biologically important intermediate that has been applied in pharmaceutical synthesis. The catalytic mechanism for furfural oxidation to maleic anhydride and 5-acetoxyl-2(5H)-furanone has been investigated in detail with identification of several key intermediates. the Partner Organisations 2014.
- Lan, Jihong,Chen, Zhuqi,Lin, Jinchi,Yin, Guochuan
-
-
Read Online
- Maleic anhydride yield during cyclic n-butane/oxygen operation
-
Cycling catalyst between a net oxidizing and reducing gaseous environment has been practiced commercially to produce maleic anhydride from n-butane over vanadium pyrophosphate. Typically, the oxidation period is less than 1 min to minimize catalyst inventory. In this study, the effect of the oxidation period on maleic anhydride productivity was assessed in the range of 0.3-10 min. Irrespective of the feed gas composition during the reduction period, the productivity increased linearly with the oxidation soak time in air. A full range of reducing conditions was examined from the pure redox mode (10% n-butane in argon) to highly oxidizing conditions typical of fixed bed operation (1.4% n-butane and 18.1% oxygen). On average, maleic anhydride yield increased by up to 50% when the oxidation time was extended from 0.3 to 10 min. The maleic anhydride yield was lowest under redox mode and it was highest when the feed composition was close to equimolar in n-butane (～6%) and oxygen. Our results show that industrial CFB reactor performance may be improved considerably by efficient regeneration of the catalyst and optimization of the reducing feed gas composition.
- Shekari, Ali,Patience, Gregory S.
-
-
Read Online
- A comparison of the reactivity of "nonequilibrated" and "equilibrated" V-P-O catalysts: Structural evolution, surface characterization, and reactivity in the selective oxidation of n-butane and n-pentane
-
Changes occurring on thermal treatment of the precursor of vanadium/phosphorus mixed oxide, the industrial catalyst for the oxidation of n-butane, were studied. The precursor was mixed with stearic acid, used as an organic binder for pelletization of the powder. The calcination of the precursor leads to a partially oxidized compound, constituted of an amorphous VIV-P mixed oxide and a crystalline hydrated VV-P-O phase. The calcined compound, when left in a 1% hydrocarbon/air stream for 100 h leads to a "nonequilibrated" catalyst, and after 1000 h to the "equilibrated" catalyst. The catalytic activity of the nonequilibrated and equilibrated catalysts in n-butane and n-pentane oxidation was studied and compared; the chemical-physical features of the two catalysts were studied by means of XRD, FT-IR, chemical analysis, TGA, XPS, and TPD. Only well crystallized (VO)2P2O7 was detected in the equilibrated catalyst and a homogeneous distribution of surface centers seems to be present on its surface. In the case of nonequilibrated catalyst, a poorly crystallized (VO)2P2O7 is present together with an amorphous VIV-P-O phase and γ-VOPO4; these phases define a heterogeneous distribution of at least two kind of surface centers. This surface heterogeneity gives rise to a catalyst less selective in n-butane oxidation to maleic anhydride and less specific in the conversion of n-pentane to phthalic anhydride.
- Albonetti,Cavani,Trifiro,Venturoli,Calestani,Lopez Granados,Fierro
-
-
Read Online
- Promotion of V-P Oxide Catalyst for Butane Oxidation by Metal Additives
-
Mixed oxide catalyst V-P-O for the butane oxidation to maleic anhydride was significantly promoted by the addition of some metal cations.In paricular, the addition of a small amount of Bi (Bi/V = 0.02) was the most effective.Over the Bi-added catalyst, the MA selectiviy exceeded 70 molpercent up to the butane conversion level of 88 molpercent, attaining the maximum MA yield of 62 molpercent at 395 deg C.
- Tamaki, Jun,Morishita, Takehiro,Morishige, Hidetaka,Miura, Norio,Yamazoe, Noboru
-
-
Read Online
- n-Butane Oxidation to Maleic Anhydride and Furan with no Carbon Oxide Formation using a Catalyst derived from VO(H2PO4)2
-
The oxidation of n-butane at 390 deg C over a catalyst derived from VO(H2PO4)2 gives only maleic anhydride and furan as products and no CO or CO2 are formed.
- Sananes, Maria T.,Hutchings, Graham J.,Volta, Jean-Claude
-
-
Read Online
- Atmospheric chemistry of benzene oxide/oxepin
-
The atmospheric chemistry of benzene oxide/oxepin, a possible intermediate in the atmospheric oxidation of aromatic hydrocarbons, has been investigated in a large volume photoreactor at 298 K and atmospheric pressure using in situ FTIR spectroscopy for the analysis. Rate coefficients of (10.0 ± 0.4) × 10-11 and (9.2 ± 0.3) × 10-12 cm3 molecule-1 s-1 have been determined for the reaction of benzene oxide/oxepin with OH and NO3 radicals, respectively. Reaction with OH radicals produces almost exclusively the (E,Z)- and (E,E)-isomers of hexa-2,4-dienedial, whereas reaction with NO3 produces (Z,Z)-hexa-2,4-dienedial and unidentified organic nitrates. Phenol has been observed as a major product of the thermal decomposition, visible and UV photolysis of benzene oxide/oxepin. The results are discussed in conjunction with the oxidation mechanisms of aromatic hydrocarbons. The major atmospheric sinks of benzene oxide/oxepin will be reaction with OH radicals and photolysis and, under smog chamber conditions with high NO2 concentrations, also reaction with NO3.
- Klotz, Bjoern,Barnes, Ian,Becker, Karl H.,Golding, Bernard T.
-
-
Read Online
- n-Butane oxidation using VO(H2PO4)2 as catalyst derived from an aldehyde/ketone based preparation method
-
A detailed study of n-butane oxidation over vanadium phosphate catalysts derived from in situ activation of VO(H2PO4)2 is described and discussed. New methods of preparation of VO(H2PO4)2 are described using the reaction of V2O5 and H3PO4 or VOPO4 · 2H2O with an aldehyde or ketone as a reducing agent. It is proposed that the enol form of the aldehyde and ketone act as the reducing agent. VO(H2PO4)2 can also be obtained by reduction of VOPO4 phases with alcohols. The catalysts derived from VO(H2PO4)2 by in situ activation in 1.5% butane in air at 400 °C for 72 h are largely disordered and, by detailed powder X-ray diffraction and laser Raman spectroscopy, are shown to be comprised mainly of disordered material containing some untransformed VO(H2PO4)2, VOPO4 phases and possibly some VO(PO3)2. The catalysts derived from all the forms of VO(H2PO4)2 investigated are found to exhibit maleic anhydride selectivities in the range 20-30% and it is concluded that the low selectivity is due to the presence of VOPO4 phases in the activated catalysts.
- Bartley,Rhodes,Kiely,Carley,Hutchings
-
-
Read Online
- Photocatalytic valorization of furfural to value-added chemicals via mesoporous carbon nitride: a possibility through a metal-free pathway
-
Strategizing the exploitation of renewable solar light could undoubtedly provide new insight into the field of biomass valorization. Therefore, for the first time, we reported a heterogeneous photocatalytic oxidation route of renewable furfural (FUR) to produce industrial feedstocks maleic anhydride (MAN) and 5-hydroxy-2(5H)-furanone (HFO) under simulated solar light (AM 1.5G) using molecular oxygen (O2) as a terminal oxidant and mesoporous graphitic carbon nitride (SGCN) as a photocatalyst. SGCN showed an excellent photoconversion (>95%) of FUR with 42% and 33% selectivity to MAN and HFO, respectively. Moreover, an excellent selectivity towards MAN (66%) under natural sunlight indicates a pioneering route for the sustainable production of MAN. In addition, the underlying mechanistic route of the FUR photo-oxidation was investigated via various experiments including scavenger studies, substrate studies, and electron spin resonance (ESR) studies which constructively proved the pivotal role of singlet oxygen (1O2) and holes (h+) in FUR photo-oxidation.
- Battula, Venugopala R.,Chauhan, Deepak K.,Giri, Arkaprabha,Kailasam, Kamalakannan,Patra, Abhijit
-
p. 144 - 153
(2022/01/19)
-
- Highly Efficient Biobased Synthesis of Acrylic Acid
-
Petrochemical based polymers, paints and coatings are cornerstones of modern industry but our future sustainable society demands greener processes and renewable feedstock materials. A challenge is to access platform monomers from biomass resources while integrating the principles of green chemistry in their chemical synthesis. We present a synthesis route starting from biomass-derived furfural towards the commonly used monomers maleic anhydride and acrylic acid, implementing environmentally benign photooxygenation, aerobic oxidation and ethenolysis reactions. Maleic anhydride and acrylic acid, transformed into sodium acrylate, were isolated in yields of 85 % (2 steps) and 81 % (4 steps), respectively. With minimal waste and high atom efficiency, this biobased route provides a viable alternative to access key monomers.
- Feringa, Ben L.,Hermens, Johannes G. H.,Jensma, Andries
-
supporting information
(2021/12/16)
-
- Method for preparing maleic anhydride
-
The invention relates to a method for oxidizing biomass-based furan derivatives furfural and 5-hydroxymethyl furfural into maleic anhydride under photocatalysis of metal oxide or loaded metal oxide. According to the method, furfural or 5-hydroxymethyl furfural is used as a reaction substrate, oxygen is used as an oxidizing agent, metal oxide or loaded metal oxide is used as a catalyst, and selective oxidation of furfural or 5-hydroxymethyl furfural into maleic anhydride is realized under the irradiation of visible light of 400-650nm. The method comprises the following reaction processes: dissolving a substrate in a solvent, adding a catalyst, carrying out oxygen replacement and sealing on gas in a photoreactor, and carrying out a reaction at a reaction temperature of not more than 40 DEG C for not less than 0.5 h under irradiation of visible light of 400-650 nm to generate maleic anhydride. The synthesis method may have important application to preparation of maleic anhydride under mild conditions.
- -
-
Paragraph 0024-0041; 0044-0065
(2021/04/14)
-
- Insights into the catalytic mechanism of 5-hydroxymethfurfural to phthalic anhydride with MoO3/Cu(NO3)2in one-pot
-
Recently, we reported a synthetic approach to obtain renewable phthalic anhydride (PA) from 5-hydroxymethfurfural (HMF) with a yield of 63.2% using MoO3/Cu(NO3)2 as a catalyst in one pot, for the first time. The reaction pathway has been elucidated in our previous study. Herein, the synergistic catalytic mechanism of MoO3/Cu(NO3)2 for the oxidation of HMF to PA was investigated. The commercially available MoO3 (c-MoO3) with superior characteristics, including more lattice oxygen and better oxygen-donating capacity, provides higher activity for the oxidation of HMF to PA. More importantly, the synergy between c-MoO3 and Cu(NO3)2 ensured the high yield of PA through the Mo6+/Mo4+ redox couple facilitated by the redox cycling of Cu2+/Cu+ with the assistance of oxygen.
- Feng, Yunchao,Jia, Wenlong,Li, Weile,Lin, Lu,Sun, Yong,Tang, Xing,Zeng, Xianhai,Zhao, Xiaoyu,Zuo, Miao
-
p. 5656 - 5662
(2021/08/24)
-
- Endo Selectivity in the (4 + 3) Cycloaddition of Oxidopyridinium Ions
-
The (4 + 3) cycloaddition of 2-trialkylsilyl-4-alkylbutadienes with an N-methyloxidopyridinium ion affords cycloadducts with high regioselectivity and excellent endo selectivity.
- Fu, Chencheng,Harmata, Michael,Keto, Angus B.,Krenske, Elizabeth H.,Liu, Jinchu,Regalado, Erik L.,Roseli, Ras Baizureen,Sungnoi, Wanna,Wang, Heather
-
p. 8302 - 8306
(2021/11/01)
-
- One-Pot Synthesis of Renewable Phthalic Anhydride from 5-Hydroxymethfurfural by using MoO3/Cu(NO3)2 as Catalyst
-
Herein, a synthetic pathway to renewable phthalic anhydride (PA) from 5-hydroxymethfurfural (HMF) in one pot is reported. The commonly available catalysts MoO3 and Cu(NO3)2 play a crucial role in integrating the multiple steps of the reaction, namely decarbonylation of HMF to active furyl intermediate (AFI), oxidation of HMF to maleic anhydride (MA), Diels–Alder cycloaddition of AFI and MA, and subsequent dehydration, in one pot. Under mild reaction conditions, a 63.2 % yield of PA is obtained from HMF. Compared with the currently reported route to renewable PA based on the Diels–Alder cycloaddition of biomass-derived MA and furan, this convenient one-pot synthesis represents a great improvement in efficiency.
- Jia, Wenlong,Sun, Yong,Zuo, Miao,Feng, Yunchao,Tang, Xing,Zeng, Xianhai,Lin, Lu
-
p. 640 - 646
(2020/01/22)
-
- Preparation method of maleic anhydride
-
The invention discloses a preparation method of maleic anhydride, belonging to the field of maleic anhydride. The preparation method of maleic anhydride provided by the invention has the characteristics of high yield, easiness in separation, low cost, less pollution and the like. The method comprises the following steps: with 5-formyloxymethylfurfural or 5-hydroxymethylfurfural as a reaction substrate, mixing the reaction substrate with a reaction solvent, an xidizing agent, an additive and a catalyst according to a certain ratio in a reactor, and carrying out a closed reaction at a certain temperature for a certain period of time so as to obtain maleic anhydride after the reaction is finished. Accordign to the preparation method of maleic anhydride provided by the invention, oxygen in atmospheric air is used as the oxidizing agent and the biomass platform compound 5-formylmethylfurfural or 5-hydroxymethylfurfural is used as a raw material; the method has the characteristics of high yield, easiness in separation, low cost, less pollution and the like; the catalyst has the advantages of high efficiency, small dosage, simplicity and easy availability; high product yield and few byproducts are realized; reaction conditions are mild; the method has the advantages of greenness, economical performance and environmental protection performance; a conversion rate exceeds 99%, and selectivity is greater than 93%; and the purity of a separated, recrystallized and purified product is higher than 99.9%.
- -
-
Paragraph 0062-0077
(2020/06/09)
-
- Features of the Thermolysis of Li, Na, and Cd Maleates
-
Abstract: Processes of the multi-stage decomposition of maleic acid and Li, Na, and Cd maleates in an inert atmosphere are studied via thermal analysis with synchronous analysis of the composition of the released gases. Reaction mechanisms are proposed according to the data on the mass loss stages determined via thermal analysis, gaseous products, and the final solid decomposition products. It is shown that when heated to 700°C, Li and Na carbonates incorporated into the porous carbon matrix are the final products. Above 350°C, cadmium is reduced from oxide to metal and evaporates to form a porous carbon residue as the only product of thermolysis. All carbon products are X-ray amorphous. Maleic acid decomposes completely into gaseous products in the range of 133–239°C. The maleate ion is more stable in the structure of lithium maleate than in free maleic acid, and Na and Cd cations reduce its stability.
- Avdin, V. V.,Merzlov, S. V.,Nayfert, S. A.,Polozov, M. A.,Polozova, V. V.,Sakthi Dharan, C. P.,Taskaev, S. V.,Zherebtsov, D. A.
-
p. 1311 - 1318
(2020/07/21)
-
- Layered δ-MnO2 as an active catalyst for toluene catalytic combustion
-
Layered δ-MnO2 was successfully synthesized by redox reaction precipitation between KMnO4 and n-butanol. Then, the as-synthesized layered δ-MnO2 was used as catalyst for toluene catalytic combustion and showed excellent ca
- Dong, Xiaoping,Fu, Shiyu,Guo, Limin,Ida, Shintaro,Li, Renzhu,Zhang, Lingxia,Zhang, Long,Zhu, Simin
-
-
- Catalyst grading method for preparation of maleic anhydride from n-butane by oxidation
-
The invention discloses a catalyst grading method for preparation of maleic anhydride from n-butane by oxidation. N-butane is mixed with air, and obtained mixed reaction gas flows in parallel throughthree or more vanadium phosphorus oxide catalyst beds connected in series, and is contacted with a vanadium phosphorus oxide catalyst for reaction under the oxidation reaction condition, wherein according to the contact sequence with the mixed reaction gas, the three or more catalyst beds connected in series perform graded loading according to the trend of the P/V molar ratio of the catalyst beingfirstly low, high and then low, so that activity distribution of the catalyst is balanced, and the activity of the catalyst is fully exerted. With the method, the n-butane concentration in feed can be increased, the reaction hot spot of the beds is reduced, temperature distribution of the beds is uniform, occurrence of side reactions is effectively inhibited, selectivity of a product is improved,and the yield of the product maleic anhydride is increased.
- -
-
Paragraph 0065-0070
(2018/06/26)
-
- Highly Efficient Gas-Phase Oxidation of Renewable Furfural to Maleic Anhydride over Plate Vanadium Phosphorus Oxide Catalyst
-
Maleic anhydride (MAnh) and its acids are critical intermediates in chemical industry. The synthesis of maleic anhydride from renewable furfural is one of the most sought after processes in the field of sustainable chemistry. In this study, a plate vanadium phosphorus oxide (VPO) catalyst synthesized by a hydrothermal method with glucose as a green reducing agent catalyzes furfural oxidation to MAnh in the gas phase. The plate catalyst—denoted as VPOHT—has a preferentially exposed (200) crystal plane and exhibited dramatically enhanced activity, selectivity and stability as compared to conventional VPO catalysts and other state-of-the-art catalytic systems. At 360 °C reaction temperature with air as an oxidant, about 90 % yield of MAnh was obtained at 10 vol % of furfural in the feed, a furfural concentration value that is much higher than those (2 vol %) reported for other catalytic systems. The catalyst showed good long-term stability and there was no decrease in activity or selectivity for MAnh during the time-on-stream of 25 h. The high efficiency and catalyst stability indicate the great potential of this system for the synthesis of maleic anhydride from renewable furfural.
- Li, Xiukai,Ko, Jogie,Zhang, Yugen
-
p. 612 - 618
(2018/01/15)
-
- Preparation method of maleic anhydride
-
Biomass-based acetylpropionic acid is taken as a raw material, and catalytic oxidation means is adopted to prepare maleic anhydride. According to the method, a manganese compound is taken as a catalyst, oxygen or air is taken as an oxidant, and acetylpropionic acid is catalyzed to prepare maleic anhydride. The method is simple in reaction operation, mild in condition, high in acetylpropionic acidconversion rate, and good in maleic anhydride selectivity, and has important application prospects.
- -
-
Paragraph 0029-0033
(2018/03/28)
-
- PRODUCTION OF MALEIC ACID, FUMARIC ACID, OR MALEIC ANHYDRIDE FROM LEVULINIC ACID ANALOGS
-
A system and method for the conversion of a levulinate ester to maleic anhydride using a reducible oxide catalyst. Levulinic acid oxidation delivers maleic anhydride in good yields without viscosity and stability issues that make continuous production problematic. Due to the fact that levulinate esters are more amenable to processing, the conversion of levulinate esters to maleic anhydride represents an appropriate for the commercial production of maleic anhydride from renewable resources.
- -
-
Paragraph 0013-0016
(2019/01/04)
-
- METHODS FOR PRODUCTION OF TEREPHTHALIC ACID FROM ETHYLENE OXIDE
-
The present invention provides methods for the production of terephthalic acid and derivatives thereof using ethylene oxide, carbon monoxide and furan as feedstocks. The process is characterized by high yields and high carbon efficiency. The process can utilize 100% biobased feedstocks (EO via ethanol, CO via biomass gasification, and furan via known processes from cellulosic feedstocks).
- -
-
Page/Page column 26-28
(2017/01/23)
-
- Heterogeneous catalysts for the cyclization of dicarboxylic acids to cyclic anhydrides as monomers for bioplastic production
-
Cyclic anhydrides, key intermediates of carbon-neutral and biodegradable polyesters, are currently produced from biomass-derived dicarboxylic acids by a high-cost multistep process. We present a new high-yielding process for the direct intramolecular dehydration of dicarboxylic acids using a reusable heterogeneous Lewis acid catalyst, Nb2O5·nH2O. Various dicarboxylic acids, which can be produced by a biorefinery process, are transformed into the corresponding cyclic anhydrides as monomers for polyester production. This method is suitable for the production of renewable polyesters in a biorefinery process.
- Rashed, Md. N.,Siddiki,Ali, Md. A.,Moromi, Sondomoyee K.,Touchy, Abeda S.,Kon, Kenichi,Toyao, Takashi,Shimizu, Ken-Ichi
-
p. 3238 - 3242
(2017/07/28)
-
- Gas phase oxidation of furfural to maleic anhydride on V2O5/Γ-Al2O3 catalysts: Reaction conditions to slow down the deactivation
-
An alumina-supported vanadium oxide catalyst (13.9?wt.% vanadium oxide) has been characterized by different techniques and tested in the gas phase oxidation of furfural. These studies have shown that the catalyst unavoidably deactivates by deposition of maleates and resins over the surface. Full regeneration is accomplished by burning off these deposits at 773?K. The studies have also demonstrated that if the primary contact occurs at temperatures at which furfural conversion is low and then the temperature is increased in a low- to high-temperature mode, intense deposition of maleates and resins takes place and the catalyst is rapidly deactivated. The increase of the temperature does not result in removal of deposits but accelerates the deposition. Under this protocol, the yield of maleic anhydride never exceeded 30%, irrespective of the reaction conditions (temperature and O2/furfural mole ratio). In contrast, if the catalyst first contacts the reaction mixture at high oxidizing potential, then the rate of maleate and resin deposition is much slower, and so is the deactivation rate, and the catalyst can display a higher yield of maleic anhydride for a longer period of time. A high oxidizing potential can be attained at a high reaction temperature (close to full conversion). A higher oxidizing potential at a given high temperature can be accomplished by increasing the O2/furfural mole ratio. Thus, for example, first contacting the catalyst at 593?K (full conversion), 1?vol.% of furfural, and O2/furfural mole ratio?=?10, obtained an initial maleic anhydride yield of 68%, and the yield was still greater than 50% after 15?h on stream. On contacting at 573?K with 1?vol.% furfural and 20?vol.% O2, the maleic anhydride yield was initially close to 75% and was above 60% after 15?h.
- Alonso-Fagúndez,Ojeda,Mariscal,Fierro,López Granados
-
supporting information
p. 265 - 275
(2017/03/22)
-
- Reactions of Three Lactones with Cl, OD, and O3: Atmospheric Impact and Trends in Furan Reactivity
-
Lactones, cyclic esters of hydroxycarboxylic acids, are interesting biofuel candidates as they can be made from cellulosic biomass and have favorable physical and chemical properties for distribution and use. The reactions of γ-valerolactone (GVL), γ-crotonolactone (2(5H)-F), and α-methyl-γ-crotonolactone (3M-2(5H)-F) with Cl, OD, and O3 were investigated in a static chamber at 700 Torr and 298 ± 2 K. The relative rate method was used to determine kGVL+Cl = (4.56 ± 0.51) × 10-11, kGVL+OD = (2.94 ± 0.41) × 10-11, k2(5H)-F+Cl = (2.94 ± 0.41) × 10-11, k2(5H)-F+OD = (4.06 ± 0.073) × 10-12, k3M-2(5H)-F+Cl = (16.1 ± 1.8) × 10-11, and k3M-2(5H)-F+OD = (12.6 ± 0.52) × 10-12, all rate coefficients in units of cm3 molecule-1 s-1. An absolute rate method was used to determine k2(5H)-F+O3 = (6.73 ± 0.18) × 10-20 and k3M-2(5H)-F+O3 = (5.42 ± 1.23) × 10-19 in units of cm3 molecule-1 s-1. Products were identified for reactions of the lactones with Cl. In the presence of O2 the products are formic acid (HCOOH), formyl chloride (CHClO), and phosgene (CCl2O), and also maleic anhydride (C2H2(CO)2O) for 2(5H)-F. In addition both reactions produced a number of unidentified products that likely belong to molecules with the ring-structure intact. A review of literature data for reactions of other furans show that the reactivity of the lactones are generally lower compared to that of corresponding compounds without the carbonyl group.
- Ausmeel,Andersen,Nielsen,?sterstr?m,Johnson,Nilsson
-
p. 4123 - 4131
(2017/06/23)
-
- A Facile Solid-Phase Route to Renewable Aromatic Chemicals from Biobased Furanics
-
Renewable aromatics can be conveniently synthesized from furanics by introducing an intermediate hydrogenation step in the Diels-Alder (DA) aromatization route, to effectively block retro-DA activity. Aromatization of the hydrogenated DA adducts requires tandem catalysis, using a metal-based dehydrogenation catalyst and solid acid dehydration catalyst in toluene. Herein it is demonstrated that the hydrogenated DA adducts can instead be conveniently converted into renewable aromatics with up to 80 % selectivity in a solid-phase reaction with shorter reaction times using only an acidic zeolite, that is, without solvent or dehydrogenation catalyst. Hydrogenated adducts from diene/dienophile combinations of (methylated) furans with maleic anhydride are efficiently converted into renewable aromatics with this new route. The zeolite H-Y was found to perform the best and can be easily reused after calcination. Just heat and tumble: Furanics-derived hydrogenated Diels-Alder adducts can be conveniently converted, over acidic zeolites, into renewable aromatics using a solid-phase conversion strategy. The zeolite H-Y was found to perform the best and can be easily reused after calcination.
- Thiyagarajan, Shanmugam,Genuino, Homer C.,Van Der Waal, Jan C.,De Jong, Ed,Weckhuysen, Bert M.,Van Haveren, Jacco,Bruijnincx, Pieter C. A.,Van Es, Daan S.
-
p. 1368 - 1371
(2016/02/12)
-
- Highly crystalline vanadium phosphate catalysts synthesized using poly(acrylic acid-co-maleic acid) as a structure directing agent
-
Vanadium phosphate catalysts have been widely studied for the selective oxidation of alkanes to a variety of products, including maleic and phthalic anhydride. More recently they are starting to find use as low temperature liquid phase oxidation catalysts. For all these applications the synthesis of the precursor is key to the performance of the final catalyst. Changes in the preparation procedure can alter the morphology, surface area, crystallinity, oxidation state and the phases present in the final catalyst which can all affect the selectivity and/or activity of the catalyst. Adding a diblock copolymer, poly(acrylic acid-co-maleic acid) (PAAMA), during the synthesis was found to influence the crystallinity and morphology of the VOHPO4·0.5H2O precursors obtained. An optimal level of copolymer was found to form precursors that showed a faster, more efficient, activation to the active catalyst, whereas high amounts of copolymer formed thin platelets, which were prone to oxidise to undesirable V5+ phases under reaction conditions, reducing the selectivity to maleic anhydride.
- Alhumaimess, Mosaed,Lin, Zhongjie,Dummer, Nicholas F.,Taylor, Stuart H.,Hutchings, Graham J.,Bartley, Jonathan K.
-
p. 2910 - 2917
(2016/05/24)
-
- Catalytic oxidative C-C bond cleavage route of levulinic acid and methyl levulinate
-
Recently, obtaining value-added chemicals from biomass resources has attracted considerable attention. Levulinic acid is one of the most important biomass platform compounds, which could be obtained from carbohydrate biomass. In this work, levulinic acid was selectively converted into C4 product, including succinic anhydride, via catalytic oxidation with a manganese catalyst in acetic anhydride. Moreover, an unexpected product of maleic anhydride was obtained, which greatly differs from that of levulinate ester. The pathway for formation of maleic anhydride was studied by monitoring and confirming intermediates α-angelica lactone and its derivative 2-methyl-5-oxotetrahydro-2-furanyl acetate. Based on the obtained mechanistic information, the different behaviour between the oxidative cleavage of levulinic acid and levulinate ester was further discussed.
- Xia, Fei,Du, Zhongtian,Liu, Junxia,Ma, Yangyang,Xu, Jie
-
p. 72744 - 72749
(2016/08/09)
-
- A catalytic oxidation 5-hydroxy methyl furfural method for the production of maleic anhydride (by machine translation)
-
A catalytic oxidation 5-hydroxy methyl furfural catalytic the production of maleic anhydride in the new system, the method comprising bismuth compound as the catalyst, molecular oxygen as oxidant, through the catalytic selective oxidation 5-hydroxy methyl furfural preparing maleic anhydride. In the method 5-hydroxy methyl furfural from carbohydrate biomass such as can be obtained in, oxidation mild reaction conditions, is a catalytic 5-hydroxy methyl furfural catalyst for the production of maleic anhydride in the new system, has important application background. (by machine translation)
- -
-
Paragraph 0017; 0018
(2017/01/26)
-
- A New Process for Maleic Anhydride Synthesis from a Renewable Building Block: The Gas-Phase Oxidehydration of Bio-1-butanol
-
We investigated the synthesis of maleic anhydride by oxidehydration of a bio-alcohol, 1-butanol, as a possible alternative to the classical process of n-butane oxidation. A vanadyl pyrophosphate catalyst was used to explore the one-pot reaction, which involved two sequential steps: 1)1-butanol dehydration to 1-butene, catalysed by acid sites, and 2)the oxidation of butenes to maleic anhydride, catalysed by redox sites. A non-negligible amount of phthalic anhydride was also formed. The effect of different experimental parameters was investigated with chemically sourced 1-butanol, and the results were then confirmed by using genuinely bio-sourced 1-butanol. In the case of bio-1-butanol, however, the purity of the product remarkably affected the yield of maleic anhydride. It was found that the reaction mechanism includes the oxidation of butenes to crotonaldehyde and the oxidation of the latter to either furan or maleic acid, both of which are transformed to produce maleic anhydride. MA and PA together: Maleic anhydride (MA) can be produced by the one-pot oxidehydration of bio-1-butanol with a vanadyl pyrophosphate catalyst. The reaction mechanism includes the oxidation of butenes to crotonaldehyde and the oxidation of the latter to either furan or maleic acid, both of which are transformed to produce maleic anhydride.
- Pavarelli, Giulia,Velasquez Ochoa, Juliana,Caldarelli, Aurora,Puzzo, Francesco,Cavani, Fabrizio,Dubois, Jean-Luc
-
p. 2250 - 2259
(2015/07/15)
-
- EPOXY RESIN CURING AGENT
-
The epoxy resin curing agent of the present invention comprises a compound represented by the following formula (1): wherein R represents a methyl group, an ethyl group, or a hydroxyl group, and n is an integer of 1 to 3.
- -
-
-
- An investigation on surface reactivity of Nb-doped vanadyl pyrophosphate catalysts by reactivity experiments and in situ Raman spectroscopy
-
The effect of Nb when used as a promoter for vanadyl pyrophosphate, the catalyst for the oxidation of n-butane to maleic anhydride, was investigated. By means of both reactivity experiments and in situ Raman spectroscopy, it was found that the promoting effect shown by Nb occurred already for a very low amount of it, i.e., for a V/Nb atomic ratio as high as 150. The main role of Nb was to accelerate the formation of a limited amount of δ-VOPO4 on the surface of vanadyl pyrophosphate, by prompting the oxidation of V 4+ into V5+ under reaction conditions. On the other hand, the presence of Nb concentrations higher than the optimal amount led to the generation of an undesired excess quantity of VOPO4 and the formation of αII-VOPO4, as well as having a detrimental effect on the catalytic behavior. The Royal Society of Chemistry.
- Caldarelli,Banares,Cortelli,Luciani,Cavani
-
p. 419 - 427
(2014/02/14)
-
- PROCESS FOR MAKING CHEMICAL DERIVATIVES
-
Process and methods for making glycolic acid chemical intermediates and derivatives from biomass are described herein.
- -
-
Paragraph 0166
(2014/02/16)
-
- Promoted role of Cu(NO3)2 on aerobic oxidation of 5-hydroxymethylfurfural to 2,5-diformylfuran over VOSO4
-
The promoted effect of Cu(NO3)2 on aerobic oxidation of 5-hydroxymethylfurfural (HMF) to 2,5-diformylfuran (DFF) catalyzed by VOSO4 in acetonitrile was intensively investigated. It was revealed that Cu(NO3)2 facilitated the activation of VOSO 4 to generate active V5+ species via the generation of NOx gas. The high DFF selectivity is ascribed to Cu2+ cation which can effectively prohibit oxidative CC bond cleavage reaction of HMF and prevent radical reaction of DFF to humins. In addition, the polarity of solvent plays a great role on high selectivity of DFF.
- Jia, Xiuquan,Ma, Jiping,Wang, Min,Du, Zhongtian,Lu, Fang,Wang, Feng,Xu, Jie
-
p. 231 - 236
(2014/07/08)
-
- Renewable production of phthalic anhydride from biomass-derived furan and maleic anhydride
-
A route to renewable phthalic anhydride (2-benzofuran-1,3-dione) from biomass-derived furan and maleic anhydride (furan-2,5-dione) is investigated. Furan and maleic anhydride were converted to phthalic anhydride in two reaction steps: Diels-Alder cycloaddition followed by dehydration. Excellent yields for the Diels-Alder reaction between furan and maleic-anhydride were obtained at room temperature and solvent-free conditions (SFC) yielding 96% exo-4,10-dioxa-tricyclo[5.2.1.0]dec-8-ene-3,5-dione (oxanorbornene dicarboxylic anhydride) after 4 h of reaction. It is shown that this reaction is resistant to thermal runaway because of its reversibility and exothermicity. The dehydration of the oxanorbornene was investigated using mixed-sulfonic carboxylic anhydrides in methanesulfonic acid (MSA). An 80% selectivity to phthalic anhydride (87% selectivity to phthalic anhydride and phthalic acid) was obtained after running the reaction for 2 h at 298 K to form a stable intermediate followed by 4 h at 353 K to drive the reaction to completion. The structure of the intermediate was determined. This result is much better than the 11% selectivity obtained in neat MSA using similar reaction conditions.
- Mahmoud, Eyas,Watson, Donald A.,Lobo, Raul F.
-
supporting information
p. 167 - 175
(2014/01/06)
-
- A metal-free, carbon-based catalytic system for the oxidation of lignin model compounds and lignin
-
Nitrogen-containing graphene material (LCN) has been identified as an effective catalyst for the oxidation of β-O-4 and α-O-4 types of lignin model compounds in the presence of tert-butyl hydroperoxide, to provide aromatic aldehydes, acids and other organic chemicals in high yield. The transformations of five lignin model compounds over LCN were investigated systematically. Instrumentation analysis, kinetic study and radical trapping experiments highlight the mechanistic features of the reaction, including: 1) the reaction pathway starts by benzylic C-H or C-OH bond activation, followed by Cα-Cβ or Cα-O bond cleavage, and finally further oxidation of intermediate aromatics; and 2) the reaction follows a free-radical mechanism with all the key steps involving radical species. In addition, the LCN proved to be a highly stable catalyst; no significant activity decrease was observed for four consecutive runs, and X-ray photoelectron spectroscopy analysis indicates negligible decrease in the content of the active nitrogen species in the catalyst. Notably, this new catalytic system can be extended to the oxidative depolymerisation of real lignin, to produce a significant portion of liquefied, low-molecular-mass products. Low mass, high conversion: Nitrogen-containing graphene-based carbon material has been used to establish a metal-free catalytic system for the oxidation of α-O-4 and β-O-4 types of lignin model compounds in the presence of tert-butyl hydroperoxide (see figure). In the oxidative depolymerization of organosolv lignin, a significant portion of liquefied, low-molecular-mass product is produced. Copyright
- Gao, Yongjun,Zhang, Jiaguang,Chen, Xi,Ma, Ding,Yan, Ning
-
p. 825 - 834
(2014/07/08)
-
- A novel approach to understanding and modelling performance evolution of catalysts during their initial operation under reaction conditions-Case study of vanadium phosphorus oxides for n-butane selective oxidation
-
In heterogeneous catalysis, catalyst precursor activation and subsequent initial operation ('conditioning') under reaction conditions are often highly dynamic steps which are important in delivering effective catalyst performance over time scales of years. In many cases however, the phenomena occurring in both steps are often poorly understood. A novel approach to assess the conditioning step, comprising advanced catalyst testing methods in micro-reactors, catalyst characterisation and detailed kinetic and activity modelling techniques is demonstrated for a model system: the selective oxidation of n-butane to maleic anhydride (MA) using a pre-activated vanadium phosphorus oxide (VPO) catalyst. A transient kinetic model for the conditioning step is presented which describes the decline of population of active sites for three reaction pathways on the catalyst surface over time. Two reaction pathways, n-butane - > MA and n-butane - > COx decay similarly with time whilst a third, MA - > COx declines very sharply. The approach used provides important mechanistic information on catalyst reaction kinetics whilst also providing understanding the impact of reaction conditions on the catalyst during conditioning.
- Wilkinson,Simmons,Stitt,Baucherel,Watson
-
p. 249 - 260
(2013/04/10)
-
- Synthesis and characterization of a renewable polyester containing oxabicyclic dicarboxylate derived from furfural
-
Techniques using biomass-based materials have become important to reduce the impacts of global warming and the depletion of petroleum resources. Changing biomass from edible to inedible is essential to solve global food issues. Furan derivatives are ideal chemicals for green chemistry because they are produced from inedible biomass resources. Here, we report the preparation of a biomass-based oxabicyclic dicarboxylic anhydride derived from furan derivatives and its polymerization with several α,ω-diols to polyoxabicyclates. 1H NMR spectra and MALDI-TOF MS measurements verified the chemical structure of the polyoxabicyclates. Polyoxabicyclates prepared using 1,3-propanediol or 1,4-butanediol could be moulded into elastic films by melt pressing. Tensile strength testing of the films indicated that they were highly elastic. Furthermore, the films had good transparency in the visible region.
- Tachibana, Yuya,Yamahata, Masayuki,Kasuya, Ken-Ichi
-
p. 1318 - 1325
(2013/06/26)
-
- Direct synthesis of phenol from benzene catalyzed by multi-V-POMs complex
-
A novel catalyst, [Mo2V2O9(bpy) 6][PMo11VO40], was synthesized by the self-assembling of [PMo11VO40]4- and [Mo 2V2O9(bpy)6]4+ unit and characterized by elemental analyses, TG, IR, X-ray powder diffraction and X-ray single crystal diffraction. [Mo2V2O9(bpy) 6][PMo11VO40] with multi-isolated active sites showed good catalytic activities for hydroxylation of benzene to phenol. A high yield of phenol (25.5%) with selectivity to phenol of 90.7% was obtained using H2O2 as oxidant. The catalyst can be recycled for 5 times while its structure was unchanged and its catalytic activity was maintained.
- Yang, Hua,Wu, Qing,Li, Jun,Dai, Wen,Zhang, Hengyun,Lu, Dan,Gao, Shuang,You, Wansheng
-
-
- Design, synthesis and in vitro kinetic study of tranexamic acid prodrugs for the treatment of bleeding conditions
-
Based on density functional theory (DFT) calculations for the acid-catalyzed hydrolysis of several maleamic acid amide derivatives four tranexamic acid prodrugs were designed. The DFT results on the acid catalyzed hydrolysis revealed that the reaction rate-limiting step is determined on the nature of the amine leaving group. When the amine leaving group was a primary amine or tranexamic acid moiety, the tetrahedral intermediate collapse was the rate-limiting step, whereas in the cases by which the amine leaving group was aciclovir or cefuroxime the rate-limiting step was the tetrahedral intermediate formation. The linear correlation between the calculated DFT and experimental rates for N-methylmaleamic acids 1-7 provided a credible basis for designing tranexamic acid prodrugs that have the potential to release the parent drug in a sustained release fashion. For example, based on the calculated B3LYP/6-31G(d,p) rates the predicted t1/2 (a time needed for 50 % of the prodrug to be converted into drug) values for tranexamic acid prodrugs ProD 1-ProD 4 at pH 2 were 556 h [50.5 h as calculated by B3LYP/311+G(d,p)] and 6.2 h as calculated by GGA: MPW1K), 253 h, 70 s and 1.7 h, respectively. Kinetic study on the interconversion of the newly synthesized tranexamic acid prodrug ProD 1 revealed that the t1/2 for its conversion to the parent drug was largely affected by the pH of the medium. The experimental t1/2 values in 1 N HCl, buffer pH 2 and buffer pH 5 were 54 min, 23.9 and 270 h, respectively. Graphical Abstract: [Figure not available: see fulltext.]
- Karaman, Rafik,Ghareeb, Hiba,Dajani, Khuloud Kamal,Scrano, Laura,Hallak, Hussein,Abu-Lafi, Saleh,Mecca, Gennaro,Bufo, Sabino A.
-
p. 615 - 635
(2013/09/02)
-
- Maleic anhydride catalyst and method for its preparation
-
The present invention provides a process for producing a vanadium/phosphorus oxide catalyst by (i) preparing a catalyst precursor powder containing vanadium, phosphorus and an optional promoter element; (ii) converting the catalyst precursor powder into an activated catalyst by heat treatment; (iii) and compressing the activated catalyst into a desired shape to form the vanadium/phosphorus oxide catalyst. The vanadium/phosphorus oxide catalyst may be used in the production of maleic anhydride by the catalytic oxidation of hydrocarbon feed streams.
- -
-
Page/Page column 12-13
(2012/04/04)
-
- Preparation of vanadium phosphate catalyst precursors for the selective oxidation of butane using α,ω-alkanediols
-
Vanadium phosphate catalyst precursors were prepared from V 2O5 and H3PO4 or VOPO 4·2H2O using α,ω-alkanediols (1,4-butanediol, 1,5-pentanediol and 1,6-hexanediol) as both the reducing agent and the solvent. A series of layered VOHPO4·HO(CH 2)nOH (n = 4-6) materials intercalated with α,ω-alkanediols were obtained. The performance for butane oxidation of the final catalysts formed via the in situ transformation of the VOHPO 4·HO(CH2)nOH precursors under reaction conditions is described. The final catalysts derived from the alkanediol intercalated materials were found to exhibit relatively low selectivities to maleic anhydride and comprised of VV (VOPO4) phases with an amorphous VIV phase. However, when a crystalline (V IVO)2P2O7 phase is present, with small amounts of VV phases, as with materials prepared with 1,4-butanediol, the specific and intrinsic catalytic activity are higher.
- Fan, Xiao-Bing,Dummer, Nicholas F.,Taylor, Stuart H.,Bartley, Jonathan K.,Hutchings, Graham J.
-
experimental part
p. 52 - 57
(2012/06/16)
-
