PTQ Q4 2026 Issue

to changes in cracked stock ratio or hydrogen partial pres- sure, and a potential penalty in volume swell. Conventional catalyst strategy In broad terms, CoMo-type catalyst systems have tradition- ally been valued for strong direct desulphurisation perfor- mance, while NiMo-type systems are often preferred when hydrogenation functionality and denitrogenation capacity become more important. The latest technologies in catalysts must deliver both high HDS and HDN to reduce nitrogen inhibition and provide refiners with a lower required operat - ing temperature to meet ULSD specifications, thus resulting in a longer cycle length. The practical implication is clear: refiners need a catalyst that retains its performance as the environment shifts from bulk sulphur removal towards deep desulphurisation under refractory nitrogen constraints, requiring active phase struc - tures that are not only intrinsically active but also morpho- logically optimised to sustain the relevant pathways under real industrial conditions. Carbazole-type molecules do not simply add to the total nitrogen level; they alter the competitive environment at active sites on the surface of the catalyst and make deep sulphur removal more difficult. As a result, a catalyst must offer not only activity but also accessible, durable active functionality capable of sustaining both sulphur removal and nitrogen handling throughout the run. Next-generation ULSD catalyst solution The newest catalyst technology focuses on generating highly dispersed nanoscale sulphide structures that uti- lise reactor volume efficiently across all stages of sulphur removal, while maintaining the balance between direct desulphurisation and hydrogenation-assisted pathways, which becomes critical in nitrogen-constrained ULSD

service. This balanced response is particularly valuable when LCO or other cracked feedstocks are blended into the diesel pool, when hydrogen pressure is moderate and when sulphur specifications are low. In this operating environment, catalyst performance must be evaluated against four simultaneous demands: • Deep sulphur removal. • Nitrogen tolerance. • Stability through the cycle. • High catalyst activity across different feedstocks. Many conventional catalysts perform strongly in one or two of these areas. The developed TK-594 HyBRIM catalyst generation addresses all four requirements at the same time. Figure 2 presents scanning transmission electron micros- copy (STEM) coupled with energy-dispersive X-ray spec- troscopy (EDS) elemental maps of the active metals. The images compare the spatial distribution of Co and Mo in the conventional CoMo catalyst with the trimetallic Co-Mo-Ni distribution in TK-594 HyBRIM, which exhibits a more homogeneous distribution of active metals throughout the catalyst particle, whereas CoMo displays localised regions of higher metal concentration. A more uniform active-metal distribution improves the accessibility of catalytic edge sites, leading to better uti- lisation of the active phase under commercial operating conditions. Rather than concentrating the active metals in localised regions, the trimetallic architecture promotes a more even distribution of catalytic functionality throughout the catalyst particle. This structural difference provides a mechanistic expla- nation for the improved catalytic performance observed under refractory nitrogen conditions. A more homogene - ous active-phase distribution increases the probability that reacting molecules encounter accessible catalytic edge sites throughout the catalyst particle instead of only in localised high-concentration regions.

Improved utilisation of active metals enhances hydrogena- tion functionality while reduc- ing diffusion-related limitations inside the catalyst pore struc- ture. The resulting catalyst for- mulation therefore maintains a more balanced combination of HDS and HDN activity through- out the operating cycle. Although catalyst perfor - mance depends on several structural parameters, active- phase dispersion is one of the key characteristics govern- ing catalyst utilisation. The improved dispersion observed for TK-594 HyBRIM provides a structural explanation for its enhanced HDS and HDN per- formance, particularly when processing feeds containing refractory nitrogen compounds.

Figure 2 STEM-EDS elemental mapping illustrating homogeneous active-metal distribu- tion in TK-594 HyBRIM

PTQ Q4 2026