06 Teachers has got appreciation letter on Teacher’s Day 2009 that is given by Assistant commissioner.

 

           *B.K.ROY, PGT(Chem) ,Kendriya Vidyalaya,AFS,Darbhanga

INDEX TERM:- oxidation catalysts,metalloporphyrin,capacity,isolation

This research paper presents a robust, surface immobilized oxidation catalysts and methods of making and using such catalysts. This can play a role in a method of the preparation that involves carrying out catalysis over an extended period of time without loss of capacity. The synthetic metalloporphyrins that lack nature’s globin protection must maintain physical separation of the porphyrins active metal sites to avoid self oxidation. If not, during the catalytic reaction, monomeric oxo-metal adducts can be converted to µ-oxo dimers by auto-oxidation and catalytic activity can be lost. This research paper demonstrates the need for efficient heterogeneous catalysis system ,that is ,system in which a solid phase carrying a catalyst is connected with a fluid phase containing reactant and oxidant .Reactants adsorbed on the surface of catalyst.In such systems catalytic metal centers can be maintained in isolation from each other, and the catalyst can be easily recovered and products are desorbed.

1.   INTRODUCTION: -

A system is provided including an article having a surface and a catalytic metal atom, capable of oxidation, covalently immobilized at the surface via plurality of covalent bonds, but being free of direct covalent bonding to the surface.[1-2] In particular, this research paper relates to inorganic surfaces including silica, alumina, niobium oxide, or tantalum oxide, or a combination there of an catalytic metal atoms including Fe,Mn,Cr,Ni,Co,Ru and Os.The catalytic metal atom , covalently immobilized at the surface via a plurality of covalent bonds can be immobilized via bonding through at least one atom that is bonded directly to the surface. The article preferably is an inorganic, mesoporous structure in the pores of which are covalently bonded a plurality of metalloporphyrins.In particular, the catalytic metal atom ,such as iron ,manganese chromium,nickel,cobalt ,rhenium and osmium are covalently bonded to a porphyrin structure which is bonded to an alumina or silica surface via bonds between the amine groups of the porphyrin structure of the alumina or silica surface. The dopant atoms can include niobium and tantalum atoms. The present investigation is to provide a technique for immobilizing a catalytic metal atom at a support in a manner allowing secure immobilization of the metal atom. The reactants include substances to be oxidized, oxidants, and any other species brought into proximity of a metal center for effecting a reaction at the metal center.

2.   METHODLOGY:-

This research project relates generally to surface immobilization of molecules and more particularly to immobilization of a metal containing heterocyclic at an in organic surface via covalent linkage remote from the metal.[ 3] The partial oxidation of Hydrocarbons is a very important chemical reactions . It may rank as one of the most difficult of organic transformations. Nature provides partial oxidation of hydrocarbons via the monoxygenase enzymes of the cytochrome P450 family, which is generally process xenobiotcs to generate hydroxylated metabolits. The reaction utilizes oxygen and reducing agent to effect alkane oxidation, and involves an intermediate including an iron porphyrin group. The synthetic metalloporphyrins that lack nature’s globin protection must maintain physical separation of the porphyrins active metal sites to avoid self oxidation. If not, during the catalytic reaction, monomeric oxo-metaladducts can be converted to µ-oxo dimers by auto-oxidation and catalytic activity can be lost. This demonstrates the need for efficient heterogeneous catalysis system ,that is ,system in which a solid phase carrying a catalyst is connected with a fluid phase containing reactant and oxidant .In such systems catalytic metal centers can be maintained in isolation from each other, and the catalyst can be easily recovered.[4-8] 

   (i) PLAN OF WORK:-The present investigation is to provide a technique for immobilizing a catalytic metal atom at a support in a manner allowing secure immobilization of the metal atom.Reactants in this project include substances to be oxidized , oxidants ,and any other species brought into proximity of a metal center for effecting a reaction at the metal center.

(ii) MATERIALS AND METHOD:-Metal doped mesoporous solid phase materials , specifically Nb-doped materials will be synthesized from an inorganic siliceous pre curso (trimethyalammonium silicates (TMAS) or (27 % sodium silicate solution) and an organic cationic trimethylammonium surfactant (C_n H _2n+1(CH₃)₃ NBr).

In the first case, 50g of TMAS wibe stirred for 10 min after the addition of 0.5g of sulfuric acid (H₂SO₄). 6.8g of cetyltrimethyl

Ammonium bromide (CTMABr) dissolved in 20.3g of water (H₂O) will be then mixed with TMAS solution and stirred for 30 min. A desired amount of

Niobium ethoxide dopant precursor will be gradually introduced into the silica loosely bounded and stirred for 30 minutes. 10 gram of H₂O will then be added to the gel which will then be aged at a constant temperature within the range of 100-180 ⁰ C.

In the second case, 3.65 g. of     CTMABr will be completely dissolved in H₂O . To this solution, 22.2 g. of sodium silicate dispersed in 50 g. water is slowly added at room tem. With vigorous stirring .The Ph 0f the mixture is adjusted to 11.5 by diluted    H₂SO₄   and dopant.Precursor is gradually introducing in to the silica gel. The resulted gel mixture is continuously stirred for 3 hours at room temp. before it is aged hydrothermally at a temp. range of   100-180 ⁰ C. The chemical properties of both the samples will be studied.

CHEMICALS REQUIRED :-      In this      research work the need of chemical is trimethyl ammoniumsilicates ( TMAS)     or 27 % sodium silicate solution and an organic cationic trimethylamonium surfactant. (C_n H _2n+1(CH₃)₃ NBr).

EXAMPLE:- In corporation of catalytic metal atom onto supporting chemical structure as follows:-

A catalytic metal atom capable of catalyzing an oxidation reaction of a reactant and oxidant, specifically an iron atom is incorporated into the H₂T_NH2PP supporting chemical structure of H₂T_NH2PP ( 1 gram) and 1 gram of anhydrous FeBr₂ are refluxed in 200 ml of dry tetrahydrofuran under nitrogen for three hours . The solvent was removed by a rotary evaporator an extracted by CHCl₃. The separated CHCl₃. layer is treated with 2 ml KOH and dried over anhydrous Na₂So_4.The anhydrated solution is then reduced to 20 ml and 10 ml of methanol and 3 -4 drops of hydrobromic acid are added to it.Thus we found a fine black purple amin –substituted iron porphyrin (Fe(iii) T_NH2PPBr) has been recovered by removal of the solvents at room temperature.

 

Conclusion :-

This research paper presents a robust, surface immobilized oxidation catalysts and methods of making and using such catalysts.This can play a role in a method of the preparation that involves carrying out catalysis over an extended period of time without loss of capacity.

 

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7.   The selective partial oxidation of Alkenes using zeolite based catalysts . Phthalocyanine(pc) ship – in –Bottle species ;Norman Herron; pp25-38, j. coord chem. 1988 vol. 19 no month  

8.   Olefin Epoxidation and Alkane Hydroxylation catalyzed by Roust sulfonated Manganese and iron porphyrins supported on cationic ion- Exchange Resins; Sandro Campestrini et el; pp1999 -2006; inorg. Chem.. 2007 vol. 31.no. 11 no month.

 

                                                                      PGT(Chemistry)