甲基噻吩在HY分子筛上的吸附、脱附及转化行为

Adsorption, desorption and conversion of methylthiophene on HY zeolite

    摘要
  • 摘要: 由NH4Y分子筛制备了HY分子筛,运用N2吸附、NH3-TPD和Py-FTIR等手段表征HY分子筛的物化性能;采用智能重量分析仪(IGA)方法研究了甲基噻吩(2-甲基噻吩、3-甲基噻吩)在HY分子筛上的吸附-脱附行为;采用程序升温脱附-质谱(TPD-MS)联用手段研究了甲基噻吩在HY分子筛上的转化行为。结果表明,在200 ℃下 2-甲基噻吩和3-甲基噻吩在HY分子筛中的强B酸上发生强化学吸附作用,与B酸结合后生成了甲基噻吩的碳正离子结构进而发生了歧化反应、脱烷基反应以及裂化反应;与2-甲基噻吩不同的是,3-甲基噻吩与HY通过一定的氢转移反应生成了3-甲基四氢噻吩,且200 ℃吸附条件下3-甲基噻吩比2-甲基噻吩更容易发生裂化反应。

     

    Abstract: HY zeolite obtained from NH4Y was characterized by N2 physisorption, NH3-TPD, and in-situ Py-FTIR. The adsorption, desorption, and conversion of methylthiophene on the HY zeolite was investigated by using the intelligent gravimetric analysis (IGA) and temperature programmed desorption-mass spectrum (TPD-MS). The results indicated that 2-methylthiophene and 3-methylthiophene are strongly chemisorbed on the strong Brnsted acid sites of HY zeolite, which promote the disproportionation, dealkylation and cracking reactions at 200 ℃. Compared with 2-methylthiophene, 3-methylthiophene is prone to crack and form 3-methyltetrahydrothiophene via the hydrogen transfer reactions.

     

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