Hydroxylation of Phenol over Ti-MCM-41 and TS-1

1995 ◽  
Vol 60 (3) ◽  
pp. 451-456 ◽  
Author(s):  
Kornelia Kulawik ◽  
Günter Schulz-Ekloff ◽  
Jiří Rathouský ◽  
Arnošt Zukal ◽  
Jiří Had
Keyword(s):  
Hydrogen Peroxide ◽  
Reaction Rate ◽  
Hydroxylation Of Phenol ◽  
Oxidation Of Phenol ◽  
Mcm 41

In the oxidation of phenol by hydrogen peroxide over titanium containing MCM-41 materials, practically only para isomers are formed. The exclusive para selectivity is proposed to be due to the different strength of adsorption for the para and ortho isomers influencing the overall reaction rate or the faster polymerization of the ortho product. The former mechanism is more probable.

Copper/MCM-41 as catalyst for photochemically enhanced oxidation of phenol by hydrogen peroxide

2001 ◽  
Vol 68 (1-3) ◽  
pp. 129-133 ◽  
Author(s):  
Xijun Hu ◽  
Frank L.Y. Lam ◽  
Lok M. Cheung ◽  
Ka F. Chan ◽  
Xiu S. Zhao ◽  
...  
Keyword(s):  
Hydrogen Peroxide ◽  
Oxidation Of Phenol ◽  
Enhanced Oxidation ◽  
Mcm 41

scholarly journals Study on phenol oxidation with H2O2

2005 ◽  
Vol 70 (10) ◽  
pp. 1137-1146 ◽  
Author(s):  
Jin Zhang ◽  
Ying Tang ◽  
Jia-Qing Xie ◽  
Jian-Zhang Li ◽  
Wei Zeng ◽  
...  
Keyword(s):  
Hydrogen Peroxide ◽  
Schiff Base ◽  
Catalytic Oxidation ◽  
Reaction Rate ◽  
Mathematic Model ◽  
Phenol Oxidation ◽  
Oxidation Of Phenol

Two new ligands, 1-hydroxy-5- 4-(2-hydroxybenzylideneamino)pheno - xy -3-oxapentane (HL1) and 1-methoxy-5- 4-(2-hydroxybenzylideneamino)pheno - xy -3-oxapentane (HL2), and their Mn(III) complexes were synthesized and characterized. The two new Schiff base Mn(III) complexes were used to mimic peroxidase in the oxidation of phenol by hydrogen peroxide. The effect of the mole ratio of H2O2 to the complex, pH and temperature on the reaction rate was investigated. The mechanism of the catalytic oxidation is discussed. A kinetic mathematic model for the oxidation of phenol catalyzed by Schiff base Mn(III) complexes has been constructed.

Photocatalytic Hydroxylation of Phenol over Ti-Containing Zeolites (TS-1, Ti-MCM-41)

2007 ◽  
Vol 124-126 ◽  
pp. 1793-1796 ◽  
Author(s):  
Gun Dae Lee ◽  
Sung Gab Kim ◽  
Hee Hoon Jeong ◽  
Seong Soo Park ◽  
Seong Soo Hong
Keyword(s):  
Hydrogen Peroxide ◽  
Catalytic Activity ◽  
Reaction Time ◽  
Product Distribution ◽  
Thermal Reaction ◽  
Hydroxylation Of Phenol ◽  
In Situ Crystallization ◽  
The Difference ◽  
Mcm 41

The photo-catalytic hydroxylation of phenol with hydrogen peroxide was carried out over TS-1 and Ti-MCM-41 catalysts. For comparison, the dark (thermal)-catalytic hydroxylation of phenol was also performed. The difference in catalytic behaviors of TS-1 and Ti-MCM-41 and product distribution in both the reactions were investigated. The TS-1 and Ti-MCM-41 catalysts having the Si/Ti ratio of 50 were prepared by in-situ crystallization and characterized using XRD, UV-DRS. In the all reactions, the main products were catechol (CAT), hydroquinone (HQ) and benzoquinone (BQ). In dark (thermal)-reaction, TS-1 showed a higher catalytic activity than Ti- MCM-41. In photo-reaction, however, the activity of Ti-MCM-41 was comparable to that of TS-1. The conversion of phenol and the selectivity to CAT in the photo-catalytic reaction were higher than those in dark (thermal)-reaction. In the all reactions, the selectivity to CAT increased remarkably when the selectivities to HQ and BQ decreased with reaction time.

scholarly journals Phenol degradation by combined photochemical-biological wastewater treatment system : kinetic modeling and optimization

2021 ◽  
Author(s):  
Maryam Edalatmanesh
Keyword(s):  
Hydrogen Peroxide ◽  
Energy Consumption ◽  
Retention Time ◽  
Rate Constants ◽  
Reaction Rate ◽  
Electrical Energy ◽  
Electrical Energy Consumption ◽  
Total Cost ◽  
Reaction Rate Constants ◽  
Oxidation Of Phenol

A dynamic kinetic model, for the oxidation of phenol in water by UV/H₂O₂ system is developed. The model is based on elementary chemical and photochemical reactions, initiated by the photolysis of hydrogen peroxide into hydroxyl radical. Numerical values of chemical reaction rate constants and photochemical parameters are taken from literature. The model is validated with data on the oxidation of phenol in the simulated and the actual UV/H₂O₂ system. Using experimental data from literature, kinetic rate constants for the reactions involving phenol oxidation intermediates, catechol and hydroquinone, are estimated. The rate constants for the reactions, where phenol oxidized to catechol and hyroquinone by hydrogen peroxide are 9x10⁸ and 2x10⁸ s⁻¹ M⁻¹, respectively. The reaction rate constants for oxidations of catechol and hydroquinone by hydrogen peroxide are found to be 9x10⁸ and 8x10⁷ s⁻¹ M⁻¹, respectively. Phenol biodegradation is best represented by a two-step Haldane model. Both photochemical and biological models are coupled together to give one single chemical-biological system. The photochemical-biological process is optimized for the retention time, electrical energy consumption, and cost. The optimization approach is solved using the Successive Quadratic Programming (SQP) method. The least retention time for this system is determined to be 99h and the optimal electrical energy consumption occurs at a photochemical retention time of 15h and a biological retention time of 92h. Calculations on the total cost for different retention times show that the incurred cost by the photochemical unit is considerably higher than that by the biological unit. However, the minimum total cost is evaluated to occur at 15.5h of photochemical retention time and 90h of biological retention time.

scholarly journals Phenol degradation by combined photochemical-biological wastewater treatment system : kinetic modeling and optimization

2021 ◽  
Author(s):  
Maryam Edalatmanesh
Keyword(s):  
Hydrogen Peroxide ◽  
Energy Consumption ◽  
Retention Time ◽  
Rate Constants ◽  
Reaction Rate ◽  
Electrical Energy ◽  
Electrical Energy Consumption ◽  
Total Cost ◽  
Reaction Rate Constants ◽  
Oxidation Of Phenol

A dynamic kinetic model, for the oxidation of phenol in water by UV/H₂O₂ system is developed. The model is based on elementary chemical and photochemical reactions, initiated by the photolysis of hydrogen peroxide into hydroxyl radical. Numerical values of chemical reaction rate constants and photochemical parameters are taken from literature. The model is validated with data on the oxidation of phenol in the simulated and the actual UV/H₂O₂ system. Using experimental data from literature, kinetic rate constants for the reactions involving phenol oxidation intermediates, catechol and hydroquinone, are estimated. The rate constants for the reactions, where phenol oxidized to catechol and hyroquinone by hydrogen peroxide are 9x10⁸ and 2x10⁸ s⁻¹ M⁻¹, respectively. The reaction rate constants for oxidations of catechol and hydroquinone by hydrogen peroxide are found to be 9x10⁸ and 8x10⁷ s⁻¹ M⁻¹, respectively. Phenol biodegradation is best represented by a two-step Haldane model. Both photochemical and biological models are coupled together to give one single chemical-biological system. The photochemical-biological process is optimized for the retention time, electrical energy consumption, and cost. The optimization approach is solved using the Successive Quadratic Programming (SQP) method. The least retention time for this system is determined to be 99h and the optimal electrical energy consumption occurs at a photochemical retention time of 15h and a biological retention time of 92h. Calculations on the total cost for different retention times show that the incurred cost by the photochemical unit is considerably higher than that by the biological unit. However, the minimum total cost is evaluated to occur at 15.5h of photochemical retention time and 90h of biological retention time.

Understanding the risks and rewards of using 50% vs. 10% strength peroxide in pulp bleach plants

TAPPI Journal ◽  
2018 ◽  
Vol 17 (11) ◽  
pp. 601-607
Author(s):  
Alan Rudie ◽  
Peter Hart
Keyword(s):  
Hydrogen Peroxide ◽  
Reaction Rate ◽  
The Other ◽  
Mechanical Pulp ◽  
Engineering Controls ◽  
Point Of Use ◽  
Process Failure

The use of 50% concentration and 10% concentration hydrogen peroxide were evaluated for chemical and mechanical pulp bleach plants at storage and at point of use. Several dangerous occurrences have been documented when the supply of 50% peroxide going into the pulping process was not stopped during a process failure. Startup conditions and leaking block valves during maintenance outages have also contributed to explosions. Although hazardous events have occurred, 50% peroxide can be stored safely with proper precautions and engineering controls. For point of use in a chemical bleach plant, it is recommended to dilute the peroxide to 10% prior to application, because risk does not outweigh the benefit. For point of use in a mechanical bleach plant, it is recommended to use 50% peroxide going into a bleach liquor mixing system that includes the other chemicals used to maintain the brightening reaction rate. When 50% peroxide is used, it is critical that proper engineering controls are used to mitigate any risks.

Preparation of Immobilized Chromium Schiff Base Complexes and their Catalytic Performance for Olefins Epoxidation

2014 ◽  
Vol 692 ◽  
pp. 240-244
Author(s):  
Gong De Wu ◽  
Xiao Li Wang ◽  
Zhi Li Zhai
Keyword(s):  
Hydrogen Peroxide ◽  
Schiff Base ◽  
Elemental Analysis ◽  
Catalytic Performance ◽  
Schiff Base Complexes ◽  
Metal Centers ◽  
Chemical Measurements ◽  
Physico Chemical ◽  
Immobilized Complexes ◽  
Mcm 41

A series of transition metal alanine-salicylaldehyde Schiff base chromium (III) complexes immobilized on MCM-41 were prepared and characterized by various physico-chemical measurements such as FIIR, XRD, HRTEM, N2 sorption and elemental analysis. The immobilized complexes were effective and stable catalysts for the epoxidation of styrene and cyclohexene with 30% hydrogen peroxide. Moreover, the metal centers were found to play important roles in the catalytic performance of immobilized complex catalysts.

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