Preparation And Study Of Keggin-type Heteropolyacid Compounds

Cyclohexyl acetate is a colorless or slightly yellow transparent liquid, it is likely to be volatile with pleasant fruit frangrance of bananas,cherries and other fruit flavor,it can be treated as vonderful organic solvent and excellent spices, often widely used in food industry as flavoring additives,it can also be further used as intermediates in the synthesis of organic macromolecules.As an important feedstock in chemical industry, phenol is called carbolic acid with colorless crystals and special smell, arousing great interesting in recently.the usage of phenol is quite wide,it can be used as an antiseptic and disinfectant in the industry,is also an important raw material for organic synthesis, can be used to synthesize phenolic resins and other polymer material.Heteropolyacids（HPAs） are transition metal oxygen anion clusters,can be designed with molecular leval,they have been widely used as excellent green catalyst and have attracted extensive attention in organic synthesis,due to their several advantages as catalysts:show excellent catalytic performance under mild operation conditions;their catalytic activity can be tuned by changing indentity of charge-compenating counter cations,heteroatoms and framework metal atoms.As a novel green catalyst,exhibiting high activity in redox/acid reaction.A series of Keggin type molybdenum substituted phosphotungstic acids(H₃PW_12-n Mon·XH₂O) have been synthesized and characterized by FT-IR, X-ray diffraction. Molybdenum substitution extent significantly affected their catalytic activity in the yield of cyclohexyl acetate, when n = 1,3,5, showing a relatively high catalytic activity, and H₃PW9Mo3O40 exhibited highest catalytic activity. The optimum reaction conditions were investigated that 0.1 mol acetic acid as reference, the mole ratio of cyclohexanol to acetic acid was 1.2, added 10 m L cyclohexane, the amount of catalyst H₃PW9Mo3O40 was 0.253 mmol, the reaction temperature was 110℃, though reacting 90 min, the yield of cyclohexyl acetate was up to 93.06%.Keggin type molybdovanadophosphoric heteropoly compound, Ni H₂PMo11VO40 prepared by acid-base neutralization method,supported on actived Ti O₂ and characterized by Fourier transform infrared Spectroscopy（FT-IR）,X-ray diffraction（XRD）,specific surface area measurements（BET）.The catalytic performances were investigated by directly hydroxylation of benzene to phenol withhydrogen peroxide as oxidant in acetic acid.various parameters,such as raction temeperature,raction time,the amouts of H₂O₂, the amouts of solvent and catalyst were studied to obtain optimal reaction conditions. As a result 35% Ni H₂PMo11VO40/Ti O₂ showed best catalytic activity compared the others,surface area changed from 6.5809m2/g to 18.2957 m2/g,the optimal reation condition were investigated that 2 m L benzene as reference,the amount of 35% Ni H₂PMo11VO40/Ti O₂ was 0.4958 g,added20 m L acetic acid and 5 m L H₂O₂,reaction temperature was 70℃,reaction time was4.5h.a convertion of benzene was 13.99% with the slectivity of phenol was 100% at the optimal reation condition.the catalytic can be used 4 times and the catalytic activity did not reduced too much,still remain high catalytic perpormance.