Immobilization of Fe, Mn and Co tetraphenylporphyrin complexes in MCM-41 and their catalytic activity in cyclohexene oxidation reaction by hydrogen peroxide

2008 ◽  
Vol 282 (1-2) ◽  
pp. 149-157 ◽  
Author(s):  
Andréia A. Costa ◽  
Grace F. Ghesti ◽  
Julio L. de Macedo ◽  
Valdeilson S. Braga ◽  
Marcello M. Santos ◽  
...  
2011 ◽  
Vol 46 (4) ◽  
pp. 345-354
Author(s):  
Zoheb Karim ◽  
Qayyum Husain ◽  
Rohana Adnan ◽  
Naseem Akhtar

The peroxidase/reverse micelle (RM) system effectively catalyzed the oxidation reaction in cyclohexane, while peroxidase from bitter gourd in aqueous buffer exhibited low catalytic activity. The oxidation of methyl parathion (MPT) has been optimized with effects of pH in the water pools, concentration of peroxidase and degree of surfactant hydration (Wo). The peroxidase/RM system showed a strong pH dependency. Its optimum catalytic activity was obtained when the peroxidase/RM was prepared in a buffer of pH 3.0. The effect of different redox mediators on the peroxidase-catalyzed oxidation of MPT was investigated. MPT was slowly oxidized by the peroxidase/RM system while the addition of phenol as a redox mediator strongly enhanced the catalytic performance of the peroxidase/RM system. Hydrogen peroxide strongly inhibited the activity of peroxidase; when the H2O2 was present at more than 0.80 mM, the MPT transformation was significantly reduced.


2007 ◽  
Vol 124-126 ◽  
pp. 1793-1796 ◽  
Author(s):  
Gun Dae Lee ◽  
Sung Gab Kim ◽  
Hee Hoon Jeong ◽  
Seong Soo Park ◽  
Seong Soo Hong

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.


2019 ◽  
Vol 9 (3) ◽  
pp. 811-821 ◽  
Author(s):  
Zhao-Meng Wang ◽  
Li-Juan Liu ◽  
Bo Xiang ◽  
Yue Wang ◽  
Ya-Jing Lyu ◽  
...  

The catalytic activity decreases as –(SiO)3Mo(OH)(O) > –(SiO)2Mo(O)2 > –(O)4–MoO.


Author(s):  
Mohsen Nikoorazm ◽  
Maryam Khanmoradi ◽  
Masoumeh Sayadian

Introduction:: MCM-41 was synthesized using the sol-gel method. Then two new transition metal complexes of Nickel (II) and Vanadium (IV), were synthesized by immobilization of adenine (6-aminopurine) into MCM-41 mesoporous. The compounds have been characterized by XRD, TGA, SEM, AAS and FT-IR spectral studies. Using these catalysts provided an efficient and enantioselective procedure for oxidation of sulfides to sulfoxides and oxidative coupling of thiols to their corresponding disulfides using hydrogen peroxide at room temperature. Materials and Methods:: To a solution of sulfide or thiol (1 mmol) and H2O2 (5 mmol), a determined amount of the catalyst was added. The reaction mixture was stirred at room temperature for the specific time under solvent free conditions. The progress of the reaction was monitored by TLC using n-hexane: acetone (8:2). Afterwards, the catalyst was removed from the reaction mixture by centrifugation and, then, washed with dichloromethane in order to give the pure products. Results:: All the products were obtained in excellent yields and short reaction times indicating the high activity of the synthesized catalysts. Besides, the catalysts can be recovered and reused for several runs without significant loss in their catalytic activity. Conclusion:: These catalytic systems furnish the products very quickly with excellent yields and VO-6AP-MCM-41 shows high catalytic activity compared to Ni-6AP-MCM-41.


1979 ◽  
Vol 44 (4) ◽  
pp. 1015-1022 ◽  
Author(s):  
Viliam Múčka

The catalytic properties of two-component catalyst nickel oxide-cadmium oxide with the proportions of the components covering the whole composition region 0-100% were examined by studying the decomposition of hydrogen peroxide in aqueous solution on it. In the range 0-25 mol.% CdO, cadmium oxide is found to affect infavourably the ability of nickel oxide to chemisorb oxygen. The amount of the chemisorbed oxygen increases several times on gamma irradiation of the samples. The effect of cadmium oxide on the catalytic activity of the system shows up in fresh samples only indirectly via the changed amount of the oxygen chemisorbed. In older samples the initial catalytic activity of the system is changed, which can be explained based on the concept of bivalent catalytic centres in terms of the co-action of the catalytic centres of the two oxides, which are in equilibrium. The irradiation of the system under study speeds up the processes leading to the establishing of this equilibrium which is thermally very stable, and results in a substantial increase of the catalytic activity of the samples investigated.


1988 ◽  
Vol 53 (8) ◽  
pp. 1636-1646 ◽  
Author(s):  
Viliam Múčka ◽  
Kamil Lang

Some physical and catalytic properties of the two-component copper(II)oxide-chromium(III)oxide catalyst with different content of both components were studied using the decomposition of the aqueous solution of hydrogen peroxide as a testing reaction. It has been found that along to both basic components, the system under study contains also the spinel structure CuCr2O4, chromate washable by water and hexavalent ions of chromium unwashable by water. The soluble chromate is catalytically active. During the first period of the reaction the equilibrium is being established in both homogeneous and heterogeneous catalytic systems. The catalytic activity as well as the specific surface area of the washed solid is a non-monotonous function of its composition. It seems highly probable that the extreme values of both these quantities are not connected with the detected admixtures in the catalytic system. The system under study is very insensitive with regard to the applied doses of gamma radiation. Its catalytic properties are changed rather significantly after the thermal treatment and particularly after the partial reduction to low degree by hydrogen. The observed changes of the catalytic activity of the system under study are very probably in connection with the changes of the valence state of the catalytically active components of the catalyst.


2019 ◽  
Vol 21 (40) ◽  
pp. 22598-22610 ◽  
Author(s):  
Nan Zhang ◽  
Fuyi Chen ◽  
Longfei Guo

We demonstrate for the first time that the Pd1Ag single-atom alloys exhibit a high catalytic activity for formate oxidation reaction.


RSC Advances ◽  
2015 ◽  
Vol 5 (122) ◽  
pp. 100693-100696 ◽  
Author(s):  
Masaki Takahashi ◽  
Takane Imaoka ◽  
Kimihisa Yamamoto

The size-dependent catalytic activity for alcohol oxidation was investigated using the platinum subnanoclusters synthesized by the dendrimer template method.


2021 ◽  
Author(s):  
Panyapat Ponchai ◽  
Kanyaporn Adpakpang ◽  
Sareeya Bureekaew

Utilization of metal-organic frameworks as heterogeneous catalysts is crucial owing to their abundant catalytic sites and well-defined porous structures. Highly robust [Cu3(trz)3(μ3-OH)(OH)2(H2O)4]∙2H2O (trz = 1,2,4-triazole) was employed as a catalyst...


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