Preparation Of Keggin-and Dawson-Structured Heteropoly Compounds And Their Catalytic Performances

Heteropoly acid and its salts are paid wide attention by the researchers because of their special acidic compounds, "quasi-liquid phase behavior", and multi-functional (acid, oxidation, Photoelectrocatalytic) advantages in the field of catalysis. They can be used as high performance acid,oxidational or dual-function catalyst in the homogeneous and heterogeneous systems. The heteropoly acid, being loaded, can improve the catalytic activity of stability, be easy to recycle, and be more conducive to non-homogeneous catalytic reaction. In this dissertation, twelve kinds of heteropoly acid catalysts were prepared, and characterized by IR and XRD. They were applied to the esterification of citric acid, synthesis of acetals and ketals from pentaerythritol with carbonyl compounds and prepration of anthraquinone from liquid-phase oxidation of anthracene. Some receive satisfied results were obtainded.1. The acid catalysis reaction of Keggin-type heteropoly acid(1) Esterification of citric acidSynthesis of tributyl citrate from citric acid and butanol catalysed by phosphotungstic acid supported on active carbon (HPW/C), the reaction conditions such as the impactors of esterification rate and the catalyst's reusing stability were studied, and the results show that molar ratio of citric acid and butanol was 1:6, catalyst amount was 1.2% (silicon tungsten acid loading 18.0%), reaction temperature 150℃and reaction time 4h, the esterification rate is up to 92.3%. Catalyst is of stability and good performance. Even re-used five times, the esterification yield only fell by about 0.7%.(2) The acetals and ketals reactions of pentaerythritolSynthesis of ketals from 2,2-bis(hydroxymethyl)propane-1,3-diol and acetophenone catalysed by phosphotungstic acid supported on active carbon (HPW/C), and the reaction conditions as follows:the amount of catalyst 0.2g (phosphotungstic acid loading of 22.1%), acetophenone/pentaerythritol in the molar ratio 3.2:1, toluene as solvent, reaction temperature 130-140℃and reaction time 2.5 h. and the yield was 91.2%. Catalyst is of stability and good performance. Even re-used five times, the esterification yield only fell by about 3%.2. The oxidation catalysis of Heteropoly compounds(1) The oxidation catalysis of Keggin-and Dawson-type heteropoly compounds Prepared more than 10 types of heteropoly acid catalysts, used IR identified the structure of the prepared catalysts and applied in prepration of anthraquinone from liquid-phase oxidation with anthracene, some meaningful results were obtained.(2) The oxidation catalysis of Mo-V-P-Dawson-type heteropoly acid under Microwave radiationUsing self-made Dawson-type vanadium phosphorus molybdenum heteropoly acid as a catalyst to synthesis of anthraquinone with anthracene under microwave radiation, examined a variety of factors on the oxidation reaction, its yield was reached 93.8%. This method is mild, short reaction time, catalytic effect is good and non-polluting the environment.