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A unique Taylor‐vortex membrane reactor (TVMR) design for continuous gas‐liquid reactions is presented in this work. The reactor consists of a cylindrical rotor inside a stationary concentric cylindrical vessel, and a flexible system of equispaced baffle rings surrounding the rotor. This restricts the annular cross section to a small gap between the baffles and the rotor, and divides the annulus into 18 mixing zones. The baffles support a 6 m long PFA tubular membrane that is woven around the rotor. At 4 mL/min inlet flow rate, the TVMR showed a plug‐flow behavior and outperformed the unbaffled reactor, having 5–12 times lower axial dispersion. The continuous aerobic oxidation of benzyl alcohol was performed for 7 h using the Pd(OAc)2/pyridine catalyst in toluene at 100 °C and 1.1 MPa oxygen pressure. A stable conversion of 30% was achieved with 85% benzaldehyde selectivity, and no pervaporation of organics into the gas phase. [ABSTRACT FROM AUTHOR]

[Display omitted] • Catalytic aerobic oxidation of glucose over HPA-2 was considered as two steps. • A rate matching exists between the glucose oxidation and the catalyst re-oxidation. • Higher O 2 pressures are required at higher temperatures for the rate matching. • The Mars-van Krevelen mechanism was verified by the consistency in kinetics. • Rate relationships among the reactions in the HPA-2 aqueous solution were studied. Catalytic aerobic oxidation of biomass-derived carbohydrates is a promising way to sustainably produce formic acid. Understanding the rate relationships among catalyst reduction, catalyst re-oxidation and acid-catalyzed reactions occurring in catalytic systems is significant for the revelation of catalytic mechanism and the selection of reaction conditions. Herein, the rate relationships among the multiple reactions over an excellent homogeneous catalyst, H 5 PV 2 Mo 10 O 40 (HPA-2) were investigated. A rate matching relationship between catalyst reduction and catalyst re-oxidation was unveiled by the separate redox kinetics of catalyst, indicating that higher O 2 pressures are required to maintain the activity of HPA-2 at higher temperatures. The consistency between the separate redox kinetics and the catalytic oxidation provided the first kinetic evidence of the Mars-van Krevelen mechanism for catalytic oxidation of carbohydrates. Furthermore, rate relationships among the multiple reactions at different conditions were discussed to clarify the correlation between product selectivity and reaction conditions. [ABSTRACT FROM AUTHOR]

N-hydroxyphthalimide (NHPI) was synchronously synthesized and immobilized on crosslinked polystyrene (CPS) microspheres via a short-cut of polymer reactions, obtaining the heterogenous catalyst. Some compositional catalysts were constituted by CPS-NHPI microspheres and metal salts, and they were used in the oxidation reactions of 1-phenylethanol with molecular oxygen as oxidant. Among four co-catalysts, vanadyl acetacetonate (VO(acac) 2 ), Co(OAc) 2 , CoCl 2 and Mn(OAc) 2 , the catalytic activity of VO(acac) 2 is the best although cobalt and manganese salts are conventional co-catalysts of NHPI. Under mild conditions, CPS-NHPI microspheres in combination with VO(acac) 2 can transform selectively 1-phenylethanol into acethenone with a conversion of 40%. [ABSTRACT FROM AUTHOR]

Cu I -catalyzed aerobic oxidation of tertiary amines as the substrate involves active radicals as the oxidized intermediates, in which the reduced intermediates, Cu I complexes, play a role of oxygen carriers to activate O 2 into the proton/electron/hydrogen-atom acceptor, while tertiary amines serve as the corresponding donor and afford alpha aminoalkyl carbon-centered radicals. Cu I -catalyzed oxidation of various tertiary amines using aerobic O 2 diffused from air as the ultimate oxidant and air-stable Cu II salts as the catalyst precursor was adopted as the chain initiation for radical polymerization of methyl methacrylate (MMA) in dimethylsulfoxide at 90 °C. The polymerization kinetics was monitored by gas chromatography, while the molecular weight and stereotacticity of PMMA were determined by gel-permeation chromatography and nuclear magnetic resonance spectroscopy. Triethylamine behaved as an efficient substrate while Cu II /2,2′-bipyridine complexes displayed a higher catalytic activity. The polymerization proceeded in a conventional fashion at a comparable rate even using several micromol of Cu II /2,2′-bipyridine complexes per liter, leading to syndiotactic-rich PMMA (syndiotacticity >55%) with an alpha-amino terminal moiety as the residue from the tertiary amine substrate, which was confirmed by UV-induced benzophenone-initiated radical polymerization using the so-obtained PMMA as the macro-sensitizer. The catalyst-performance analysis suggested that each molecule of Cu II /2,2′-bipyridine complexes could generate 3 × 10 2 propagating PMMA radicals in 3 h under optimal conditions. [ABSTRACT FROM AUTHOR]

Highlights: [•] Twelve mixed-metal double metal hexacyanocobaltates have been prepared. [•] The activity of these solids has been tested for oximes oxidation by molecular oxygen or air. [•] Metal leaching does not take place during the reaction catalysis. [•] A reaction mechanism is proposed. [ABSTRACT FROM AUTHOR]

[Display omitted] • ZrCl 4 /NaOH-catalyzed lignin-first oxidation of corn stalk was achieved. • Yields of phenolic monomers was up to 13.2 wt% via lignin-first oxidation. • Phenolic carbonyls were the dominated products with high selectivity of 93%. • Cellulose-rich residues proved the fragmentation and dissolution of lignin streams. Lignin-first biorefinery of corn stalk via ZrCl 4 /NaOH-catalyzed aerobic oxidation for phenolic carbonyls production was reported. Under the co-catalysis of ZrCl 4 and NaOH, lignin in corn stalk was oxidized into phenolic aldehydes (p -hydroxybenzaldehyde, vanillin, and syringaldehyde), ketones (p -hydroxyacetophenone, acetovanillone, and acetosyringone), acids (p -hydroxybenzoic acid and vanillic acid), and other derivatives. Reaction conditions, including time, temperature, ZrCl 4 dosage, NaOH dosage, MeCN/H 2 O ratio, and initial O 2 pressure were comprehensively screened, and the optimal lignin-derived monomer yields of 13.2 wt% was obtained. Among these aromatic compounds, phenolic aldehydes were the main products, and the overall selectivity of phenolic carbonyls was as high as 93%. Cellulose-rich residues after lignin-first oxidation were further characterized by thermogravimetry and analytical pyrolysis with corn stalk as the control, proving the good fragmentation and dissolution of lignin streams. In general, ZrCl 4 /NaOH-catalyzed lignin-first oxidation provided a novel approach for lignin valorization, and achieved the highest reported phenolic carbonyls selectivity. [ABSTRACT FROM AUTHOR]

The novel complex Ind(CO)3Mo–Ru(CO)2Cp (1) (Ind=η5-indenyl,Cp=η5-cyclopentadienyl), as well as other hetero and homo metallic complexes of molybdenum and ruthenium are catalyst precursors in the aerobic oxidation of THF under ambient conditions. Selectivities towards γ-butyrolactone of up to 70% are obtained. For the first time in this transformation, propylformate is isolated besides the lactone. [Copyright &y& Elsevier]