【作者】 赵训志；

【导师】 王鉴；

【作者基本信息】 大庆石油学院 ， 化学工艺， 2006， 硕士

【摘要】 复合金属氧化物(CMO)是烃类选择氧化与氨氧化中重要的催化剂,具有优良的氧化还原性能、热稳定性和机械强度以及较强的表面酸碱性,长期以来在多相催化领域发挥着重要作用。尽管CMO催化剂在化工生产上已广泛应用,但对其催化机理方面的认识还十分有限。丙烷作为重要的小分子烷烃,将其选择氧化制丙烯酸是一条很有前途的路线。CMO是该反应已知的最好的催化剂,其通过自身的氧化还原反应,活化烷烃和分子氧。在此过程中其氧化还原性质是影响发挥催化作用的重要因素。我们利用脉冲反应器,催化剂预氧化与丙烷氧化反应轮流进行,重点考察了反应条件下Mo-V-Te-Nb-O催化剂氧化丙烷的性能及其再氧化性能,并对催化剂的结构进行了表征。通过对催化剂的吹扫实验验证了其晶格氧氧化机理,发现丙烷与Mo-V-Te-Nb-O催化剂晶格氧反应的主要产物为丙烯酸(AA)。改变预氧化条件,丙烷转化率、AA产率及选择性的变化表明增加预氧化时间及提高预氧化温度能增加Mo-V-Te-Nb-O催化剂上氧物种的数量及活性;预氧化时适量水的存在,可以改善催化剂表面的结构并提高产物AA的选择性。通过对比丙烷和丙烯与催化剂晶格氧反应情况和催化剂储氧能力的考察得知,催化剂上利于丙烷活化脱氢的氧物种比选择氧化生成丙烯酸氧物种的消耗速率要快得多,不同氧物种在反应过程中所起的作用不同。催化剂的酸性表征表明,200℃左右处出现主要脱附峰;失效后催化剂出现强酸中心,推测为其失效主要原因。更多还原

【Abstract】 Complex mental oxides are important catalysts during the selective oxidation andammoxidation process of hydrocarbon. They have played an important role in the heterogeneouscatalysis field for long because of their excellent properties, such as excellent redox property,thermal stability and mechanical intensity, strong acidity-basicity. The understanding on reactionmechanism of complex mental oxides is very limited even though they have been widely used.Selective catalytic oxidation of propane has been a problem from the industrial point ofview because it is less expensive but difficult to functionalize. It is promising to convert thepropane into acrylic acid and complex mental oxides have been proposed as the most active andselective catalysts in the oxidation of propane to acrylic acid. Complex mental oxides canactivate both the oxygen and the alkane through the redox reaction of itself. Catalysis of thecomplex mental oxides can be greatly effected by it’s redox property.In the present work, a significant study on the oxidation performance and re-oxidationperformance of Mo-V-Te-Nb-O catalyst was carried out using a pulse reactor in which theoxidation of propane and the reoxidation of catalyst were taken place alternatively. theconfiguration of the catalyst was also charactered. It is confirmed that propane reacts with latticeoxygen of Mo-V-Te-Nb-O catalyst to form AA under the condition of no molecule oxygen. Thequantity and activity of the oxygen species will be improved through the increasing ofpre-oxidation time and enhancing of pre-oxidation temperature, the surface configuration of thecatalyst will be improved with the presence of water in regeneration atmosphere and theselectivity of the product can also be heightened. The results showed that the consuming speed ofthe oxygen species that helping to the oxidation dehydrogenation of propane is more prompt thanthe oxygen species that selectively oxidation to acrylic acid after the study of the catalyst’sstoring oxygen using different material propane and propylene. Different oxygen species has it’sown role in the catalytic process. The desorption behaviour of ammonia on the catalysts wasstudied by means of TPD. One key desorption peak was found at the temperature about 200 ℃and an obvious desorption peak was found on the spent catalyst at the high temperature region.更多还原