CrAPO_4-5的合成及对环己烷选择性氧化的研究

SYNTHESIS OF CrAPO_4-5 MOLECULAR SIEVES AND THE RESERCHMENT OF CYCLOHEXANE SELECTIVE OXIDATION

以三乙胺为模板剂,拟薄水铝石为铝源,磷酸为磷源,在55℃恒温水热合成过程中加入硝酸铬,制备出CrAPO4-5分子筛,通过粉末X射线衍射(XRD)、红外光谱(IR)、氨程序升温脱附(NH3-TPD)、魔角核磁共振(MAS NMR)等手段进行了表征,发现所合成的分子筛具有良好的晶体结构,且证明了Cr原子进入分子筛骨架。以CrAPO4-5分子筛为催化剂,以空气为氧源,考察了反应温度、时间、引发剂等因素对环己烷选择性氧化的影响。结果表明,在环己酮为引发剂情况下,反应压力为1.6 MPa,温度为160℃,反应6 h后,环己烷转化率可达20.6%,醇酮总选择性为95.7%。说明CrAPO4-5分子筛具有良好选择性和活性,是一种温和的氧化催化剂。

By constant temperature hydrothermal method, using triethylammonium as template agent, diaspore and phosphoric as aluminium and phosphor sources respectively, adding chromic nitrate directly at 55°C and then the molecular sieve CrAPO4-5 was synthesized. The product was characterized by means of powder X-ray diffraction (XRD), framework IR spectra, NH3-TPD and MAS NMR. The result indicates that the molecular sieve has the favourable crystal structure and the Cr has been incorporated in the framework of the molecular sieve. Using CrAPO4-5 molecular sieve as catalyst and air as oxidant, the effects of temperature, time and initiator on cyclohexane selective oxidation reaction were studied. The results show that under the reaction condition of cyclohexanone as initiator, the pressure of 1.6 MPa, the temperature of 160°C and reaction time of 6 h, the conversion ratio of cyclohexane reached to 20.6% and the total selectivity of cyclohexanone and cyclohexanol can come to 95.7%. All these indicate that CrAPO4-5 molecular sieve has high selectivity and activity, and it is a mild catalyst for cyclohexane oxidation reaction.