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Catalytic Oxidation Of Toluene To Benzaldehyde Over Keggin-type Heteropolyacid Compounds

Posted on:2012-11-05Degree:MasterType:Thesis
Country:ChinaCandidate:G WangFull Text:PDF
GTID:2131330335466997Subject:Chemical processes
Abstract/Summary:PDF Full Text Request
Selective oxidation of toluene to benzaldehyde is one of the typical reactions in the selective oxidation of aromatic hydrocarbon. Benzaldehyde is important interme- diates in the organic synthesis industry,and its derivatives were widely used in synthesis of many kinds of chemicals,such as pharmaceuticals,spiceries,cosmetics, dyes,pesticide,etc.It has high annualdemands,promising market and good economic benefits.At present,alkyl chlorination of toluene in the industrial production,but the prevalence of selectivity is not high or serious equipment corrosion and complex process,production,which prevents all admriable product-benzaldehyde fromfurther usage in the line of pharmaceutics and flavor,due to some chlorides included among products.With the increasing demand of benzaldehyde,people trying to find a new processes.The Keggin type of heteropoly compounds(HPC)is very common and possess of unique properties:the double-functional property of acidity and redox,and the pseudoliquid-phase characteristic.They have been investigated extensively in catalytic field and material chemistry for their high catalytic performance and selectivity,moderate reaction conditions,non-corrosion,their easy synthesis,low cost,good thermal stability,especially for their redox and acidic properties can be controlled at atomic or molecular levels by changing the chemical composition.This study on direct partial oxidation of toluene to benzaledhyde was presented,Heteropolyacid Compounds,Heteropoly Acid Cobalt Salt Immobilized on Silylated Palygorskite as reaction catalysts,Tert-butyl hydrogen peroxide and H2O2 as oxidative reagents.The main progress and research results have been obtained as follows:1. Catalytic Oxidation of toluene to benzaldehyde over Keggin-type heteropoly CompoundsOxidation of toluene to benzaldehyde catalyzed by Keggin-type heteropoly compound Co3H2PV2Mo10O40 using TBHP(tert-butyl hydrogen peroxide)as oxidant and acetonitrile as solvent was investigated. Using infrared spectroscopy(IR),X-ray diffraction(XRD)were used to characterize the catalysts.Experiments showed that reaction temperature 90℃and reaction time 6h,the conversion of toluene was 28.50% and the selectivity of benzaldehyde was 55.50%.2. Oxidation of Toluene to Benzaldehyde with Heteropoly Acid Cobalt Salt Immobilized on Silylated PalygorskiteThe catalyst(Co4H1PV2Mo10O40/PaAPTES)of heteropoly acid cobalt salt support- ed on acid activated and silanizing palygorskite(PaAPTES)by 3-aminopropyl-triethoxy silane(APTES)was prepared via chemical bonding.The properties of the catalyst was characterized by infrared spectroscopy,X-ray diffraction,Brunauer–Emmett–Teller(B ET)specific area measurement.The catalytic activity of the catalyst was determined by the oxidation of toluene to benzaldehyde.The results show that benzaldehyde is the main product in the reaction.With the acetonitrile as solvent, the amount of catalyst is 0.3 g,the amount of H2O2(50% in volume)solution is 9.6 mL, after reaction at 90℃for 9 h,the conversion of toluene is 58% and the selectivity of benzaldehyde is 75%.The recycling tests show that the catalyst can be easily separated from the reaction system.
Keywords/Search Tags:heteropoly acid, toluene, catalytic oxidation, benzaldehyde, tert-butyl hydrogen peroxide, finc chemical intermediates, palygorskite
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