La/Hβ-Al2O3复合材料改善轻汽油醚化活性

La/Hβ-Al2O3 composite materials improve light gasoline etherification activity

  • 摘要: 采用La3+交换法制备La/Hβ-Al2O3复合材料,用于改善轻汽油的低温醚化活性。借助XRD、XRF、BET、FTIR、NH3-TPD、PyIR、FETEM-EDX等分析手段对复合材料的理化性能进行表征,其中XRD、XRF、BET和FTIR的表征结果显示,少量La3+的引入对复合材料的晶相结构和骨架结构无明显破坏作用,而适度的La3+交换反而具有扩孔效果;NH3-TPD和PyIR的分析结果表明,经La3+交换后复合材料的酸量和酸强度有所减弱,但引入的La3+可以形成新的B酸中心,使中强酸比例和B酸中心数目得到提高;FETEM-EDX分析结果证实镧物种主要存在于复合材料中的Hβ分子筛上。对该复合材料的低温醚化活性评价结果显示,La3+交换法可以改善复合催化剂的轻汽油醚化活性,催化剂0.1 La/Hβ-Al2O3表现出最佳活性,产物甲基叔戊基醚收率最高可达58.13%。对该催化剂进行300 h寿命考察,证实其具有较好稳定性及可再生性。

     

    Abstract: The La/Hβ-Al2O3 composite materials were prepared by method of lanthanum ion-exchange and used to improve the low-temperature etherification activity of light gasoline. The physical chemical properties of composite materials were characterized by a series of analytical methods, such as XRD, XRF, BET, FTIR, NH3-TPD, PyIR and FETEM-EDX. The results of XRD, XRF, BET and FTIR show that introduction of a small amount of lanthanum ions has no obvious effect on the crystalline phase and skeleton structure of the composite materials, on the contrary, moderate lanthanum ion exchange has the effect of pore-enlarging. The analysis results of NH3-TPD and PyIR show that acid content and acid strength of the composite materials have been weakened, but the introduction of lanthanum ions can form a new Brønsted acid site, which increases the ratio of medium strong acid and the amount of Brønsted acid sites. The results of FETEM-EDX analysis confirm that the lanthanum species are mainly present in the Hβ molecular sieve of composite materials. The evaluation results of etherification activity of this composite material show that the method of lanthanum ion-exchange can improve the light gasoline etherification activity of composite catalyst, in which the sample 0.1 La/Hβ-Al2O3 shows the best activity, and the yield of methyl tertiary amyl ether is up to 58.13%. The 300 h life test results show that it has good stability and reproducibility.

     

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