Vapour phase oxidation of toluene in V/Al2O3–TiO2 catalytic reactors

Clean Ar-Me conversion to Ar-aldehyde with the aid of carefully designed metallocorrole photocatalysts

Toluene, p-xylene and mesitylene were cleanly converted to their corresponding monoaldehydes via mild photooxygenation utilizing transition metal and main group β-CF₃-substituted corroles. Aldehyde yield increased as more electron-donating CH₃ groups are present on the substrate. 4-P was most efficient (TON ∼ 1072, mesitylene) via the singlet oxygen vis the superoxide mechanism.

Cu(ii) complexes of N-rich aroylhydrazone: magnetism and catalytic activity towards microwave-assisted oxidation of xylenes

The new aroylhydrazone N'-(di(pyridin-2-yl)methylene)pyrazine-2-carbohydrazide (HL) species, rich in N-donor sites, has been used to synthesize Cu(ii) compounds with different nuclearities, viz. the binuclear [Cu₂(μ-1κN³,2κN²O-L)(Cl)₃(MeOH)] (1), the octanuclear [Cu₄(μ-1κN³,2κN²O-L)₂(μ-Cl)₃(Cl)₃]₂ (2) and the 1D coordination polymer [Cu₃(μ₃-1κN³,2κN²O,3κN-L)(μ-NO₃)(NO₃)₃(H₂O)₃]_n·nNO₃ (3). They have been characterized by elemental analysis, FT-IR and single crystal X-ray diffraction. The magnetic properties of 2 and 3 have been explored using variable temperature magnetic measurements. The catalytic performances of the compounds were evaluated towards the peroxidative oxidation of o-, p- and m-xylenes under microwave irradiation, leading to the formation of the corresponding methyl benzyl alcohol, tolualdehyde and toluic acid as the major products. Complex 3 exhibits the best catalytic activity towards the oxidation of p-xylene with a total yield of 37% (4-methylbenzyl alcohol + p-tolualdehyde + p-toluic acid).

Large-scale synthesis of ultrathin tungsten oxide nanowire networks: an efficient catalyst for aerobic oxidation of toluene to benzaldehyde under visible light

As a very important chemical raw material, the selective formation of benzaldehyde from toluene at preparative or industrial levels requires the use of highly corrosive chlorine and high reaction temperatures, which severely corrodes equipment, pollutes the environment, and consumes a lot of energy. Herein, we report a robust and highly active catalyst for the benzaldehyde evolution reaction that is constructed by the surfactant-free growth of oxygen vacancy-rich W18O49 ultrathin nanowire networks. Under atmospheric pressure and visible-light irradiation, the new catalyst can selectively (92% selectivity) catalyze the aerobic oxidation of toluene to benzaldehyde with yields of above 95%.

Highly selective oxidation of toluene using air over [Fe(III)TPP]Cl supported on chitosan

The highly selective catalytic oxidation of toluene with air to benzaldehyde and benzyl alcohol in the liquid phase has been studied with the use of iron tetraphenylporphyrin (Fe TPP) supported on chitosan (CTS), (Fe TPP/CTS). The rates of toluene conversion and selectivity (aldehyde + alcohol) were subject to the reaction temperature, air pressure, and amount of iron tetraphenylporphyrin. By the use of the Fe TPP/CTS, containing 2 mg of iron tetraphenylporphyrin as catalyst, toluene oxidation with air under the optimum conditions of 190 °C and 0.6 MPa produced benzaldehyde and benzyl alcohol at 90% selectivity and 5.4% conversion of toluene, the mole turnover of the catalyst was about 6 × 106, and it could be reused efficiently for one more time. It is suggested that the amine groups (–NH2) on the chitosan chain act as a key assistor to the catalysis of Fe TPP for toluene oxidation. Compared with the conventional method of synthesizing benzaldehyde and benzyl alcohol, the new method has the advantages of reduced environmental pollution, higher selectivity for the two main products, and easy recovery of the catalyst.Key words: chitosan-supported iron porphyrin, catalysis, toluene oxidation, benzaldehyde, benzyl alcohol.

Photodegradation of toluene over TiO2–xNx under visible light irradiation

We report the photooxidation of toluene over nitrogen doped TiO(2) (TiO(2-x)N(x)) under visible light irradiation. The photocatalytic oxidation of toluene in air over TiO(2-x)N(x) powders was studied using diffuse reflectance Fourier transform infrared spectroscopy (DRIFTS), gas chromatography (GC), ion chromatography (IC), and gas chromatography mass spectrometry (GC-MS), focusing on the photocatalytic decomposition processes of toluene. Results obtained indicate that toluene, weakly adsorbed on the catalyst surface, is initially photooxidized to benzaldehyde which adsorbs onto the TiO(2-x)N(x) surface more strongly, leading to the formation of ring-opening products such as carboxylic acids and aldehydes. No gaseous intermediates were detected during the photooxidation. Major intermediates adsorbed at the catalyst surface were oxalic acid, (COOH)(2), acetic acid, CH(3)COOH, formic acid, HCOOH, and pyruvic acid, CH(3)COCOOH, whereas more complicated carboxylic species, including propionic acid, CH(3)CH(2)COOH, isovaleric acid, (CH(3))(2)CHCH(2)COOH, and succinic acid, (CH(2)COOH)(2), were also found in the early stage of the photooxidation. These intermediate products were gradually photodegraded to CO(2) and H(2)O under visible light irradiation.