Catalysis 2023 Issue

Shaping

Zeopore

Figure 1 Zeopore’s technology entails incorporation of metals (green) on the zeolite (blue) during mesoporisation, which is followed by catalyst shaping

mesoporisation technology is highly controlled and bonds the metal to the zeolite, yielding a blanket of single metal atoms over the zeolite’s external surface. As the technology employs wet chemistry, it does not require energy-demand- ing evaporation steps, as is the case with state-of-the-art impregnations. This highly controlled metal mesoporisation also does not yield metal nitrates, avoiding undesired NOx emissions in subsequent metal activation steps. On the spatial level, the deposition of the metal, specifi - cally on the external surface of the zeolites, enables benefits on several levels (see Figure 2 , bottom). First and foremost, the proximity of the metal to the acid site in the zeolite is

hereby minimised, opening the door to pronounced catalytic benefits, as demonstrated in hydrocracking, for example.2 In addition, controlled dispersion of the metal on the zeo- lite enables complete avoidance of the complications from metal inhomogeneity on the extrudate level. Phenomena such as gravity-based settling of the metal and metal sup- port interaction-based eggshell/yoke distributions are no longer concerns. Zeolites containing highly porous, dispersed and stable metals The unique properties of these metal-containing zeolites become obvious from almost any method of characteri- sation. A typical zeolite impregnation (such as incipient wetness impregnation, IWI) yields a reduction in overall porosity (see Table 1 ), which can be attributed to the dilu- tion of the zeolite phase, the latter being the most porous. Conversely, the metal mesoporisation technology, even at exceptionally high metal loadings, allows for total sur- face areas (TSA) that are similar to or larger than the starting conventional zeolite. Moreover, the mesopore surface (MSA) and total pore volume (PV) are substan- tially increased. This is the case for large pore zeolites, such as USY, and also for very dense frameworks, such as MRE. When using metals in catalysis, the metal dispersion is crucial and is typically assessed using chemisorption. For this purpose, a chemisorption methodology specific for alkaline earth, transition metals and lanthanoids has been developed. This analytical technique proves that Zeopore’s metal mesoporisation yields dispersions typically around 80%, regardless of metals or zeolite (see Figure 3 ). High dispersions were confirmed by microscopy analysis, show - ing that even with 10 wt% of Ni, it is hard to trace the atomically dispersed Ni atoms (see Figure 4 ).

Zeopore

Conventional

Crystal

Extrudate

Figure 2 The difference between conventional and Zeopore’s method of metal incorporation illustrated on crystal (top) and extrudate level (bottom)

Porosities of several zeolites prepared using Zeopore’s metal mesoporisation process

Type

Framework

Metal, wt%

TSA, m 2 /g

MSA, m 2 /g

PV, ml/g

Parent

MFI MFI MFI FAU FAU MRE MRE

none

380 330 362 724 720 156 286

25 24

0.22 0.19 0.33 0.50 0.75 0.19 0.44

Parent + IWI

9.6 (Ni) 9.8 (Ni)

Metal mesoporisation

136 194 338

Parent

None

Metal mesoporisation

Parent

None

Metal mesoporisation

9.6 (Mg)

189

Table 1

Catalysis 2023