ASTM International

Standard Guide for Metals Free Steam Deactivation of Fresh Fluid Cracking Catalysts
 N D4463/D4463M

Annotation

This guide covers the deactivation of fresh fluid catalytic cracking (FCC) catalyst by hydrothermal treatment prior to the determination of the catalytic cracking activity in the microactivity test (MAT).

The hydrothermal treatment of fresh FCC catalyst, prior to the MAT, is important because the catalytic activity of the catalyst in its fresh state is an inadequate measure of its true commercial performance. During operation in a commercial cracking unit, the catalyst is deactivated by thermal, hydrothermal and chemical degradation. Therefore, to maintain catalytic activity, fresh catalyst is added (semi) continuously to the cracking unit, to replace catalyst lost through the stack or by withdrawal, or both. Under steady state conditions, the catalyst inventory of the unit is called equilibrium catalyst. This catalyst has an activity level substantially below that of fresh catalyst. Therefore, artificially deactivating a fresh catalyst prior to determination of its cracking activity should provide more meaningful catalyst performance data.

Due to the large variations in properties among fresh FCC catalyst types as well as between commercial cracking unit designs or operating conditions, or both, no single set of steam deactivation conditions is adequate to artificially simulate the equilibrium catalyst for all purposes.

In addition, there are many other factors that will influence the properties and performance of the equilibrium catalyst. These include, but are not limited to: deposition of heavy metals such as Ni, V, Cu; deposition of light metals such as Na; contamination from attrited refractory linings of vessel walls. Furthermore, commercially derived equilibrium catalyst represents a distribution of catalysts of different ages (from fresh to >300 days). Despite these apparent problems, it is possible to obtain reasonably close agreement between the performances of steam deactivated and equilibrium catalysts. It is also recognized that it is possible to steam deactivate a catalyst so that its properties and performance poorly represent the equilibrium. It is therefore recommended that when assessing the performance of different catalyst types, a common steaming condition be used. Catalyst deactivation by metals deposition is not addressed in this guide, but is addressed in Guide D7206/D7206M.