PTQ Q3 2025 Issue

Figure 3 Scanning Electron Microscopy with Energy-Dispersive Spectroscopy (SEM-EDS) mapping of Ecat showing the ele - mental distribution on the cross-section of particles, including Ecat and Cat-Aid additive. Cat-Aid particles effectively trap iron and silica, as evidenced by the rings on the surface. Vanadium rings on Cat-Aid particles are clearly evident also (arrowed)

of iron offers the opportunity for iron to be captured by a separate particle metals trap additive. It is proposed that when an FCC base catalyst particle with a glassy and sticky iron-silica layer contacts a Cat-Aid particle, silica in this layer reacts with magnesium present in the additive to form magnesium silicate. Silica, as magnesium silicate, is made immobile on the additive surface. Consequently, iron becomes trapped on the additive particle and no longer exhibits any inter-particle mobility. Commercial trials have shown that the additive can alle- viate existing iron poisoning and reduce iron deposition on the FCC base catalyst particles. Once the base catalyst is cured of iron poisoning, the Cat-Aid additive minimises iron nodule formation, restoring access to the inner core for cracking. Figure 4 presents Ecat particles before and after the use of the additive. Prior to its addition, the Ecat particles surface exhibits typical iron poisoning nodular features. With the metals trap additive in circulation, the Ecat particles surface becomes smoother, with significantly fewer and less prominent iron nodules. To gather more solid evidence on the impact of Cat-Aid additive, an advanced statistical tool was employed to analyse the elemental distribution of thousands of Ecat particles before and after the additive use. As shown in Figure 5 , the surface iron distribution curve of Ecats shifts towards lower iron concentrations, with a notable reduction in the fraction of high-iron-content particles. Simultaneously, a significant increase in silica concen - tration on the additive is observed, indicating silica accu- mulation on its surface. These findings suggest that the additive effectively interacts with both iron and silica, reducing iron mobility within the unit and thereby mitigat- ing iron poisoning. The quantity of iron retained on the surface of Cat-Aid

particles is influenced by the extent of iron contamination in the Ecat and the iron content in the feed. When no iron nod- ules are present on the Ecat surface and the iron concen- tration in the feed is low, the iron ring observed in the EDS mapping of the additive appears less distinct. Nevertheless, the additive remains effective in targeting iron and other metal contaminants, particularly vanadium. Could a similar iron-trapping functionality be integrated into the base catalyst? Cat-Aid additive contains basic materials to enable the trapping of iron silicate. A base cat- alyst with such materials incorporated would see its activ- ity/acidity being severely penalised. Besides, since iron is not intraparticle mobile, any iron would struggle to migrate towards iron-trapping sites within a base catalyst particle and escape through the glassy layer to free the catalyst particle from poisoning. Mitigation of iron poisoning with metals trap additive – ACE study A steamed commercial Ecat sample with iron nodules (con- firmed with SEM) and nickel and vanadium levels of 2,200 wppm and 2,160 wppm, respectively, was evaluated using an Advanced Cracking Evaluation (ACE) unit to test the

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Figure 4 SEM images from Ecat samples before and after the addition of Cat-Aid additive

Figure 5 Iron oxide distribution in the Ecat nodule layer before and after adding Cat-Aid additive in two commercial samples

PTQ Q3 2025