Hydrogenation Of Anthraquinone Research Articles

Study on deactivation and regeneration of Pd/Al2O3catalyst in hydrogen peroxide production by the anthraquinone process

Deactivated palladium catalysts in the hydrogenation of anthraquinione were regenerated with ethanol, nitric acid, hydrogen peroxide, boiling water and steam, respectively. The deactivated and regenerated catalysts were characterized by XPS, ICP, TG, FTIR, TPD, XRD, etc., and studied in the hydrogenation of anthraquinone. The results showed that the main cause of catalyst deactivation is the coverage of the active component by deposits. The treatments by hydrogen peroxide and boiling water can effectively regenerate the deactivated catalysts.

Integrated Process of H2O2 Generation through Anthraquinone Hydrogenation−Oxidation Cycles and the Ammoximation of Cyclohexanone

The liquid−liquid-phase equilibrium of a five-component system of methanol−water−H2O2−trimethylbenzene−trioctyl phosphate was studied, and the data were correlated with UNIQUAC and NRTL models, respectively, and used for the simulation of the extraction of H2O2 with an aqueous methanol solution in the H2O2 production process based on anthraquinone hydrogenation−oxidation cycles. The results showed that, with an aqueous methanol solution for the extraction of H2O2, after a few cycles the concentration of methanol in an anthraquinone working solution becomes constant and would not influence the H2O2 production process. All of the impurities in the H2O2 solution obtained with an aqueous methanol solution as the extractant from the H2O2 generation process as well as the stabilizers and corrosion inhibitors that should be added in the H2O2 solution did not appreciably affect the direct ammoximation of cyclohexanone with NH3 and H2O2 catalyzed by TS-1. The results indicated that the processes of cyclohexanone oxime production through the direct ammoximation of cyclohexanone and H2O2 generation through the anthraquinone hydrogenation−oxidation cycles could be integrated.

Effects of lanthanum addition on Ni-B/γ-Al 2O 3 amorphous alloy catalysts used in anthraquinone hydrogenation

A series of amorphous Ni-B/γ-Al 2O 3 catalysts with different La loadings were prepared by KBH 4 reduction, characterized by inductively coupled plasma (ICP), DSC, H 2-TPD, X-ray photoelectron spectroscopy (XPS) and H 2-chemisorption, and studied in the hydrogenation of anthraquinone (AQ). In comparison with the catalyst without La loadings, the presence of proper amounts of lanthanum in the supported amorphous alloy catalyst leads to more active centers, higher extents of H 2-chemisorption, the shift of H 2 desorption peaks to lower temperatures, the enhancement of thermal stability as well as higher reaction rates and higher TOF values. The effects of lanthanum were attributed to both its structure effect, dispersing Ni, leading to more active centers and enhancing the thermal stability, and its electronic effect, resulting in electron-rich Ni, weakening the adsorption of anthraquinone and the bond strength of NiH and therefore activating the adsorbed hydrogen. However, higher La loadings were harmful to the activity because too many surface Ni active centers might be covered by La 3+ species.

Effects of lanthanum addition on Ni-B amorphous alloy catalysts used in anthraquinone hydrogenation

Amorphous Ni-B alloys with or without lanthanum were prepared by KBH 4 reduction, characterized by ICP, BET surface area measurement, XRD, TPD, H 2 chemisorption, etc., and studied in the hydrogenation of anthraquinone. The addition of lanthanum chloride in the preparation procedure leads to the incorporation of lanthanum oxide and the decrease of Ni:B ratio in the Ni-B amorphous alloy. In comparison with Ni-B, the presence of lanthanum oxide in the amorphous alloy lead to higher BET area, higher extents of H 2 chemisorption and desorption, the shift of H 2 desorption peaks to lower temperatures, and higher TOF and reaction rate in the hydrogenation of anthraquinone. The effects of lanthanum were attributed to its dispersion of Ni, leading to much more active centers and the donation of electrons to Ni and therefore activating the adsorbed hydrogen and weakening the binding energy between nickel and hydrogen. As a result, both TOF and the reaction rate in the hydrogenation of anthraquinone were increased with the addition of lanthanum.

Modelling of Katapak reactor for hydrogenation of anthraquinones

Modelling of a catalytic hydrogenation reactor is described. The catalyst, Pd on porous granules, was installed in the reactor in KATAPAK elements, produced by Sulzer GmbH. The reactor was used to hydrogenate anthraquinone compounds, dissolved in an organic solvent. This reaction is used in the production of hydrogen peroxide. Because of complex geometry and many simultaneous phenomena taking place in the reactor, any detailed modelling approach tends to lead to a large number of unknown parameters. To reach acceptable reliability, the main phenomena in the reactor were studied separately in several mock-up experiments. The models of these subsystems were combined and the resulting complete reactor model was validated by experimentation with a full-scale reactor. A certain part of the model was based on CFD calculations.

Hydrogenation of the aromatic rings of 2-ethylanthraquinone on palladium catalyst

Hydrogenation of anthraquinones at the oxygen is a key step in the industrial production of hydrogen peroxide. The reaction is very fast in the presence of palladium supported catalysts. However, these catalysts also promote the hydrogenation of the aromatic rings of the anthraquinone molecules giving place to substances not participating in the formation of hydrogen peroxide and causing a loss of active quinone. 2-ethylanthraquinone can also give tautomerization to oxanthrone and derivatives with a further loss of active quinone. The kinetics of the hydrogenation of the aromatic rings of 2-ethylanthraquinone are studied. A dual site reaction mechanism well explains the experimental findings. On the basis of this mechanism, kinetic expressions have been developed and the kinetic parameters determined. The contribution of tautomerization to the kinetic pattern has also been ascertained.

Kinetics and mechanism of the hydrogenation of substituted anthraquinones on Raney nickel catalysts

The rate and direction of the hydrogenation of anthraquinone has been established to depend considerably on the nature and position of the substituent as well as on the structure and phase composition of the catalyst. The selectivity of the process is increased by introducing electronaccepting substituents into the anthraquinone molecule or upon doping the Ni−Al alloy by additives increasing the M−H bond energy.