ZSM-5 is a widely used zeolite catalyst and is employed industrially for the methanol to gasoline (MTG) process. Even so, deactivation of ZSM-5 by coke formation constitutes a major technical and also fundamental challenge. We investigate the deactivation of a range of ZSM-5 catalysts through catalytic testing, physicochemical characterization, and powder X-ray diffraction (XRD). It is demonstrated that the unit cell changes upon deactivation. Periodic density functional theory is used to show that the change is induced by certain methyl substituted benzenes in the channel intersection in ZSM-5. This finding is corroborated by Rietveld refinement of XRD data obtained for deactivated catalysts. We are able to establish a direct correlation between the difference in the length of the a- and b-unit cell vectors and the total amount of coke, the remaining acidity, and the remaining surface area of the catalysts. This a- minus b-parameter is a straightforward descriptor that carries the essential information regarding the degree of deactivation of a ZSM-5 catalyst, and a routine measurement of a diffractogram of the catalyst can be used to quantitatively assess the degree of deactivation.

中文翻译：

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沸石催化剂H-ZSM-5失活的简单描述

ZSM-5是一种广泛使用的沸石催化剂，在工业上用于甲醇制汽油（MTG）工艺。即便如此，通过结焦使ZSM-5失活仍是一项重大技术挑战，也是一项根本性挑战。我们通过催化测试，理化特性和粉末X射线衍射（XRD）研究了一系列ZSM-5催化剂的失活。已经证明，晶胞在失活时发生变化。周期性密度泛函理论用来表明这种变化是由ZSM-5通道相交处的某些甲基取代的苯引起的。Rietveld精制针对失活催化剂获得的XRD数据，证实了这一发现。我们能够建立在长度之差有直接关系一个-和b-晶胞载体和焦炭的总量，剩余的酸度和催化剂的剩余表面积。这个a减b参数是一个简单的描述符，它包含有关ZSM-5催化剂失活程度的基本信息，并且可以使用催化剂衍射图的常规测量来定量评估失活程度。