Tungsten Catalysts And Its Applications In The Synthesis Of Adipic Acid, Etc

An environmentally benign and green process is highly desirable in the development of catalysis. One of the most important fields is to rebuild the conventional processes of petrochemical production, which measurably contribute to pollution. Currently, the industrial production of adipic acid still uses the oxidation of cyclohexanol/cyclohexanone mixture with nitric acid. The yield and selectivity are both high, but erosion is severe. Besides, the emission of N₂O,NO and the waste acid damage environment remarkably. Therefore, the development of the clean process for the adipic acid is an important subject in the chemical industries.In this work, tungsten resource with ample supply in China especially in Jiangxi province was used as catalysts in the green synthesis of adipic acid, n-butyl acetate. And we mainly carried out the following aspects of research works as follows:Adipic acid was synthesized by WO₃ catalyzed oxidation of cyclohexanol with 30% hydrogen peroxide. The influence of reaction conditions such as catalyst amount, hydrogen peroxide amount, reaction temperature and time on the oxidation was investigated. Under the optimal conditions, i. e. when n (cyclohexanol) : n(hydrogen peroxide) : n (tungsten trioxide) was 100 : 600 : 4, and the reaction temperature was 100℃, the reaction time was 6 h, the isolated yield of adipic acid could reach 67.6% and its purity was 99.8%. The catalyst could be reused for 5 times and the isolated yield of adipic acid was still above 60.2%.Adipic acid was synthesized by ammonium tungstate catalyzed oxidation of cyclohexanol with 30% hydrogen peroxide. The influence of reaction conditions such as catalyst amount, hydrogen peroxide amount, reaction temperature and time on the oxidation was investigated. Under the optimal conditions, i. e. when n (cyclohexanol) : n (hydrogen peroxide) : n (ammonium tungstate) was 100 : 550 : 1, and the reaction temperature, was 90℃, the reaction time was 6 h, the isolated yield of adipic acid could reach 78.4% and its purity was 99.8%. The catalyst could be reused for 3 times and the isolated yield of adipic acid was still stable. Adipic acid was synthesized by ammonium tungstate catalyzed oxidation of cyclohexanone with 30% hydrogen peroxide. The influence of reaction conditions such as catalyst amount, hydrogen peroxide amount, reaction temperature and time on the oxidation was investigated. Under the optimal conditions, i. e. when n (cyclohexanone) :n (hydrogen peroxide) :n (ammonium tungstate) was 100 : 400 : 0.5, and the reaction temperature was 90℃, the reaction time was 5 h, the isolated yield of adipic acid could reach 80.9% and its purity was 99.8%. The catalyst could be reused for 4 times and the isolated yield of adipic acid was 95.8% and its purity was 74.3%.In this dissertation, we found that the catalyst, ammonium tungstate, could be reused for many times and the isolated yield of adipic acid was still high. This work was different from the predecendent works in that the used catalyst was simplier, cleaner and more efficient. And the activity of the catalyst would be better, the amount of hydrogen peroxide was little, the reaction temperature was low, the amount of reaction time was short. It also showed that catalyst could be reused for many times and the isolated yield of adipic acid was still stable.SO₄^2-/ZrO₂ solid acid catalyst was prepared by hydrothermal method. The catalysts were characterized with XRD and IR. The liquid phase esterification of acetic acid and 1-butanol was performed to confirm the optimal conditions. At the same time, the influence of different factors on conversion of acetic acid was studied. The test results showed in esterification reaction the technological conditions of n-butyl acetate were as follows: the reaction time was 2h, n (n-butanol): n (acetic acid)=2:1, and w(catalyst) was 0.2% based on the total mass of initial materials. Conversion of acetic acid amounted to 99.1%. However, the conversion of acetic acid would decrease when the amount of WO₃ increased. Because the addition of WO₃ led to the reduction of the catalyst's B. E. T surface area.