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Selective oxidation of toluene to benzaldehyde is to study the selective oxidation of aromatic hydrocarbons typical one. The benzaldehyde is an important intermediate in organic synthesis industry, broad range of applications, which can be used to synthesize drugs, perfumes, cosmetics, dyes, pesticides and other chemical products, with annual demand, the market prospect is good and high economic efficiency features. Current industrial production of benzaldehyde is mostly toluene side-chain chlorinated hydrolysis method, but the prevalence of selectivity is not high or severe corrosion of equipment, process complexity and other shortcomings, because the product contains chlorine, severely limiting benzaldehyde in medicine, spices and other fields. With the increasing demand of benzaldehyde, people are trying to find new production processes. Keggin type heteropoly compounds is the most common type, which are both acidic and redox properties of the solid bifunctional catalyst, has a unique \, acidic and redox properties by changing the composition of elements in the atomic or molecular level can be adjusted such specificity; also has high catalytic activity, selectivity, mild reaction conditions and does not corrode equipment and so on. Therefore, catalysis and materials chemistry has been a hot research field. In this paper, heteropoly salt and immobilized cobalt salt of heteropoly acid as catalyst, tert-butyl hydrogen peroxide and hydrogen peroxide as the oxidant for the direct catalytic oxidation of toluene to benzaldehyde were studied. The main contents and conclusions are as follows: 1.Keggin heteropoly acid catalyzed oxidation of toluene was studied in order to prepare benzaldehyde TBHP (tert-butyl hydroperoxide) as oxidant and acetonitrile as solvent conditions, using Keggin type Co 3 H 2 PV 2 Mo 10 O 40 heteropoly salt as catalyst oxidation Toluene was prepared benzaldehyde. By infrared spectroscopy (IR), X-ray diffraction (XRD) method to characterize the catalysts. Experiments show that: the reaction at 90 ℃ for 6h, get toluene conversion was 28.50%, the selectivity of benzaldehyde reached 55.50%. 2 immobilized cobalt salt of heteropoly acid catalyzed oxidation of toluene to benzaldehyde prepared by acid-activated attapulgite (palygorskite, Pa) as the carrier, the use of chemical bonding was prepared 3 - aminopropyl triethoxysilane (3 -aminopropyl-triethoxysilane, APTES) silylation attapulgite (PaAPTES) load Keggin type heteropoly acid cobalt salt catalyst (Co 4 H 1 PV 2 < / sub> Mo 10 O 40 / PaAPTES), and infrared spectroscopy, X-ray diffraction, compared Brunauer-Emmett-Teller (BET) surface area of the catalysts were measured, etc. characterization. Conducted a catalytic oxidation of toluene to benzaldehyde reaction test. The results showed that: the introduction of Co 4 H 1 PV 2 Mo 10 O 40 / PaAPTES for the catalytic reaction, the formation of benzaldehyde is the main product. When the acetonitrile as the solvent, the catalyst in an amount of 0.3 g, 9.6 mL of hydrogen peroxide (H 2 O 2 in solution volume content of 50%), the reaction at 90 ℃ for 9 h obtain a toluene conversion was 58% and the selectivity of benzaldehyde reached 75%. And the catalyst is easily separated from the reaction system.
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