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1

Combining laccase with Cu(salen) catalysts for oxidation of kraft lignin

Zhou X. F., Tang K.

Drewno : prace naukowe, doniesienia, komunikaty

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2016

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vol. 59, nr 198

35--47

EN

The transformation of kraft lignin using laccase with Cu(salen) catalysts was studied. The effect of the laccase/MCM – to – laccase/MCM + Cu(salen)/NaY ratio on the yields of monomeric aromatic chemicals (MACs) and the molecular weight (Mw) of kraft lignin was studied. The MACs yield decreased as the ratio increased, and the vanillin yield reached its highest value when the ratio of laccase was 50 wt % at a reaction temperature of 80 °C. The formation of MACs was enhanced by using a combination of laccase with Cu(salen) catalysts, while the formation of vanillin was dominant in the process. The formation of 4-hydroxy-3,5-dimethoxy benzaldehyde, 2-methoxy phenol, 4-hydroxy-3,5- -dimethoxyphenyl ethanone, 4-hydroxy-3-methoxyphenyl ethanone, 4-hydroxy- -3,5-dimethoxy benzoic acid, 4-hydroxy benzaldehyde, and 2-methoxy-4- -vinylphenol was also found in this work. The effect of the reaction parameters on the MACs yield and the Mw of the kraft lignin was described, and the main reactions occurring in the kraft lignin were discussed.

2

The degradation of kraft lignin during hydrothermal treatment for phenolics

Tang K., Zhou X. F.

Polish Journal of Chemical Technology

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2015

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Vol. 17, nr 3

24--28

EN

Kraft lignin was hydrothermally depolymerized at low temperature/short time in water for producing value-added phenolics. The effects of residence time (15, 60 min) and reaction temperature (130, 180, 230ºC) on yields of oils and phenolic compounds were studied in detail. Total oil yield was found to range between 7% and 10%. The compositions of oils were analyzed by GC-MS to confirm the main compound to be guaiacol (2-methoxy phenol) in the range of 12–55% of oil depending on different reaction conditions. The most interesting was the finding that maximum value of total oil yield (10% of kraft lignin) and guaiacol amount (55% of oil) was obtained at 130ºC/15, 60 min which is a low reaction temperature/short time, while the residual kraft lignins were analyzed by FTIR with respect to the conversion mechanism of kraft lignin by this process.

3

The Influence of Waterin Different Sites on Multi-Channel Reactions of the Proton Transfer of Serinamide

Zhou X. M., Ma H. K., Zhang A. G., Ma K. S., Tang K., Zhou Z. Y.

Polish Journal of Chemistry

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2009

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Vol. 83, nr 4

555-564

EN

The multi-channel reactions of proton transfer of water-bridged serinamide have been investigated em ploy ing the B3LYP/6-311++G** level of thetheory. The reactants, transition states and products of four channels have been optimized. Further more, the validity of these transition states has been validated by the internal reaction coordinate (IRC). The activation energies, standard enthalpy and free energy change have also been calculated. From the free energy changes we conclude that the water molecule serving as a bridge facilitates the proton transferreaction.

4

Influence of Vibration Changes on Jahn-Teller Distortion in [Fe(H2O)6]2+ and [Fe(NO)(H2O)5]2+

Sun H. T., Li Y. M., Wang Z. Z., Su C. F., Zhou Z. Y., Tang K.

Polish Journal of Chemistry

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2009

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Vol. 83, nr 2

303-313

EN

Density functional theory (DFT) calculation and vibrational modes have been reported for the ferrous hexaaquo ions and ferrous cinqueaquo nitrosyl ions, using B3LYP gradient-corrected density functionals at standard 6-31+G(d) basis. The effect of hydrogen bonding in solvents has been influenced by polarizable continuum models (PCM). The optimized structures predict an abnormal FeO6 octahedron for Fe(H2O)6]2+ reflect ing a Jahn-Teller distortion with the H2O molecules lying in the FeO4 plane in vacuo. In [Fe(NO)(H2O)5]2+, the Jahn-Teller distortion is more evident and the H2O molecules are pushed from the FeO4 plane. Then compared with the PCM methods, the Jahn-Teller distortion has been found to strengthen in the polarizable continuum model. Moreover, with the investigation of the vibrational mode and occupied orbital, we have found that the Jahn-Teller distortion has stronger influence on nitrosyl group than on H2O molecules.