PTQ Q4 2026 Issue

≥15 wt ppm lower at all WABT

Consistently lower at all WABT

WABT (˚F)

Figure 3 HDS and HDN activity from conventional CoMo catalysts (blue) and TK-594 HyBRIM (red)

The significance of Figure 2 extends beyond morphology alone. The more uniform active phase distribution helps explain why the new catalyst is able to maintain a more balanced response between direct desulphurisation and hydrogenation-assisted pathways. That balance is critical in nitrogen-constrained ULSD service, where refractory nitro- gen compounds can suppress the hydrogenation route and reduce overall sulphur removal efficiency. A catalyst with a more accessible and better dispersed active phase is better equipped to preserve activity under these conditions. This structural advantage becomes particularly important when processing feeds containing LCO or other cracked components, where sulphur species are more refractory and nitrogen inhibition is more severe. Under these conditions, a highly dispersed active phase provides stronger HDS, HDN, and hydrodearomatisation (HDA), and more effective utilisa- tion of the hydrogenation function. This combination is particularly important when treating feeds containing straight-run diesel and LCO blends, or feeds in which carbazole-type molecules materially influ- ence EOR sulphur performance. In these cases, the unit benefits not simply from a more active catalyst, but from one that remains functionally balanced as conventional catalyst systems begin to shift too much towards one reaction path- way at the expense of another. Pilot plant evidence and commercial implication Prior to commercial launch in ULSD, an extensive pilot plant test matrix programme was conducted. In ULSD services, the catalyst was tested using 100% straight-run diesel, straight- run diesel blended with LCO, and 100% LCO to bracket the operating conditions from low to high nitrogen inhibition. Under these demanding conditions, the new catalysts consistently demonstrated enhanced HDS and HDN perfor- mance compared with the current conventional CoMo cat- alysts. The improvement was particularly evident for feeds containing elevated concentrations of carbazole-type nitro- gen compounds, where catalyst hydrogenation functionality becomes increasingly important. Figure 3 demonstrates that TK-594 HyBRIM consistently provides improved HDS and HDN performance when tar- geting ULSD conditions across a range of hydrogen partial pressures relevant to ULSD service. For enhanced under- standing of the sulphur and nitrogen removal mechanisms,

both GC-AED nitrogen- and sulphur-selective analyses were performed on feed and products from both catalysts, as shown in Figures 4 and 5 . In Figure 4, TK-594 HyBRIM achieves approximately 98% removal of refractory carbazole species, compared with approximately 80% for conventional CoMo catalysts under identical operating conditions, thereby significantly reduc- ing nitrogen inhibition. By more effectively converting these refractory nitrogen compounds, TK-594 HyBRIM preserves hydrogenation functionality for the conversion of the most refractory sulphur species. Carbazole HDN proceeds through a sequence of partially hydrogenated intermediates before C-N bond cleavage occurs. When carbazole conversion is incomplete, these intermediate species remain adsorbed on hydrogenation-ac- tive sites and continue competing with refractory sulphur molecules for catalytic access. Their presence becomes increasingly important in the lower zone of the catalyst bed, where the remaining sul- phur compounds are predominantly sterically hindered (and therefore highly refractory) dibenzothiophene derivatives that rely heavily on hydrogenation-assisted desulphurisa- tion pathways. The higher carbazole conversion achieved by TK-594 HyBRIM therefore not only lowers the concentration of refractory nitrogen compounds entering the lower catalyst sections but also minimises the concentration of partially hydrogenated carbazole intermediates that would other- wise continue occupying hydrogenation-active sites. As a result, a greater fraction of the catalyst hydrogenation func- tionality remains available for conversion of refractory sul- phur compounds throughout the catalyst bed. The near-complete removal of carbazole species therefore represents considerably more than improved HDN activity. It demonstrates that the catalyst maintains the hydrogena- tion-active sites available throughout the catalyst bed, pre- serving the hydrogenation functionality required for deep HDS of the remaining refractory sulphur species. Consequently, improved carbazole removal directly con- tributes to sustained deep HDS performance under indus- trial operating conditions, as demonstrated by both pilot plant testing and commercial applications. These observa- tions further illustrate the close relationship between nitro- gen removal and deep sulphur conversion.

PTQ Q4 2026