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用顺磁共振(ESR)方法及程序升温脱附(TPD)技术研究了由甲醇合成催化剂(加少量助剂)和ZSM—5分子筛组成的复合催化剂,在由合成气(CO+H_2)一步直接合成汽油反应中的积炭行为。探讨了催化剂上积炭、表面酸、催化活性变化的关系。研究表明,在复合催化剂积炭中的碳含量与ESR信号强度有很好的对应关系,因此,可将ESR用于催化剂上积炭的定量监视;由于催化剂的积炭,使复合催化剂中ZSM—5分子筛的强酸及中强酸位逐渐中毒,导致甲醇转化为汽油馏分的活性降低。
The composite catalysts consisting of methanol synthesis catalyst (with a small amount of auxiliaries) and ZSM-5 zeolite were studied by means of paramagnetic resonance (ESR) and temperature programmed desorption (TPD) Carbon deposition in synthetic gasoline reaction. The relationship between coke deposition, surface acidity and catalytic activity was discussed. The results show that there is a good correspondence between the carbon content and the ESR signal intensity in the composite catalyst carbon deposition. Therefore, the ESR can be used for the quantitative monitoring of the carbon deposition on the catalyst. Due to the carbon deposition of the catalyst, the ZSM- 5 zeolite acid and strong acid sites gradually poisoning, resulting in reduced activity of methanol into gasoline fractions.