Catalysis 2022 issue

Low-cost mesoporous zeolites deliver catalytic benefits Improved catalystsmake compelling business cases in refining, petrochemicals, and the conversion of methanol, biomass, andwaste plastics

KURT DU MONG and DANNY VERBOEKEND Zeopore Technologies

I n the refining and petrochemi - cal industry, zeolitic catalysts are widely used to produce automo - tive fuels and petrochemical base chemicals efficiently and sustaina - bly. Still, a significant disadvantage is their narrow micropore structure, which instills severe access and dif - fusion limitations. As a result, only a minor part of the zeolites’ poten - tial (the crystal surface) is utilised. Complementing the zeolite’s micropores (0.5-1 nanometer) with a network of larger high-quality mesopores (2-20 nanometer) signif - icantly increases accessibility to the active sites inside the zeolite crys - tals. It boosts the catalysts’ selectiv - ity, activity, and lifetime (see Figure 1 ). As a result, mesoporous zeolites have been identified as a supe - rior catalyst in a plethora of crack - ing, isomerisation, and alkylation reactions. 1,2 However, based on the fre - quent use of exotic chemicals and case-specific challenging unit oper - ations, mesoporous zeolites have gained a reputation for having a high price tag and poor industrial scalability. 2 In addition, established mesoporisation technologies often imply a reduction of desired intrin - sic zeolitic properties, especially for challenging zeolite frameworks like faujasites. Unsurprisingly, initia - tives to commercialise mesoporous zeolites have often met a silent end. Zeopore aims to restore the rep - utation of mesoporous zeolites. Its technology platform allows it to convert not just USY or ZSM-5 but any commercially and readily available zeolite into a high-quality mesoporous zeolite at an afforda -

Active sites in narrowmicropores

Conventional zeolite

Mesoporous zeolite

100 nm

Zeolite crystal

1 nm

Mesopores

Utilised

Not utilised

Oil molecule

Figure 1 Schematic impact on the increased accessibility of the active sites located in mesoporous zeolites

ble price. Such high-quality meso - porous zeolite fully retains desired intrinsic properties, such as acidity, microporosity, and crystallinity. The company uses standard unit opera - tions and commodity chemicals to accomplish this (see Figure 2 ). As a result, its processes imply industrially relevant produc - tivity and a low fingerprint in terms of required chemicals and resulting wastewater (see Figure 3 ). Moreover, scale-up has been proven within months from opti -

mised gram-scale recipes to indus - trially required volumes, delivering on-spec materials in a reproducible manner (see Figure 4 ). Synergy with zeolite crystallisation and catalyst making Post-synthetic mesoporisation is typically applied to zeolite powders and is, therefore, best applied after zeolite crystallisation and before catalyst production. Zeopore has established that its mesoporisation process offers significant synergies with both steps (see Figure 5 ). For example, in established zeolite crystallisation, growing small crys - tals is often preferred, as smaller crystals (‘nanozeolites’) imply larger external surfaces and yield superior catalytic performance. However, the manufacture of such crystals is often associated with low crystal - lisation yields, long crystallisation (and lead) times, excessive use of expensive ingredients, and difficult filtration and scalability. 4 Mesoporisation removes the need

Tunable

Any zeolite

Accessibility

Economic & scalable

Retained intrinsic properties

Figure 2 Zeopore has a unique offering in accessible mesoporous zeolites

Catalysis 2022 45