Catalysis 2026 Issue

Macro pore packings for liquid feed distributors only

Coal tar liquid (2,143 B/D)

Hydrotreated coal tar liquid

Expanded HDS catalyst bed

∆P2

∆P1

MagAFS

Furnace or heater

Coal tar liquid HDS reactor

Heat exchanger

reticulated top bed packings. In the absence of smaller par- ticles (sizes in the nm range), the HDS reactor has main- tained its almost original catalyst activity and operated smoothly, without disruption, for five years after the instal - lation of the filter. Table 1 summarises the catalyst perfor- mance based on reactor WABT. As shown in Table 1, the annual average WABT of the HDS reactor increased only 1ºC (or essentially no change) since installing the MagAFS filter. In fact, the reactor WABT in 2024 was even lower due to the lower throughput required by reduced market demand. Minimising pressure drop changes After installation in October 2020, the MagAFS filter con - tinues to control (minimise) pressure drop change in the front-end heat exchanger and HDS reactor. Since installa - tion, pressure drop in the HDS reactor (R4101A) has grad- ually stabilised, requiring no unscheduled shutdowns for unplugging or cleaning. During the annual scheduled shutdown in November 2021, new SCTC top macropore packings were installed above the catalyst bed in the HDS reactor. After start-up, the pressure drop in the cleaned reactor was reduced and has been maintained at this new lower level. Similarly, pressure drop in the front-end heat exchanger (E4101G) has remained essentially unchanged during this period. Figure 5 shows the pressure drop data for both units, E4101G (heat exchanger) and R4101A (HDS reac - tor), from October 2020 to December 2025. Neither unit has experienced any unexpected shutdowns (due to rising pressure drop) or catalyst deactivation (caused by pore Figure 4 Installation of MagAFS filter in front of light coal tar HDS reactor in CSCC plant

(No changes in pressure drops of reactor & heat exchanger and no changes in reactor weight average bed temperature (WABT) during 3+ years after the MagAFS lter installation

Figure 3 MagAFS filter for coal tar liquid HDS reactor

94.9 wt% aromatics (including 92 wt% benzene), 13.16 Bromine Number, and 0.882-0.886 g/ml density. Product from the reactor required <0.2 ppmw sulphur, 20 ppmw nitrogen, 0.06-0.08 Bromine Number, and 0.882-0.886 g/ ml density. Figure 4 is a photo of the filter, installed and started up in October 2020, which has continuously processed 52,000 MT/Y (2,143 B/D) of light coal tar feed to the HDS reactor without incident or disruption for more than three years. The light coal tar stream was introduced from the feed surge tank on the left-hand side in Figure 4 through two MagAFS filters arranged in parallel positions to feed the HDS reactor. Each filter consisted of two filtration cham - bers in series. Protecting catalyst activity It has been demonstrated that, five years after installing the MagAFS filter, catalyst activity is still protected, with essentially no change in reactor weight average bed tem - perature (WABT). A previous report2 on the same coal tar naphtha stream revealed that up to 97.6% of solid particles were removed by the filter, and only 2-3% of the original particles (mostly larger particles) were allowed to enter the HDS reactor. Before installation of the MagAFS filter, the reactor required very costly shutdowns every six to nine months to skim the reactor bed, which included removal and replace - ment of about one-third of the catalyst bed and the entire

WABT of HDS reactor three years after installing the MagAFS filter

Average temperature (ºC)

1/12-31/12/2021

1/12-31/12/2022

1/12-31/12/2023

1/12-31/12/2024

Reactor inlet Reactor outlet

240

237 258

240 257

234 253

25 15

Inlet/outlet difference

WABT

247.5

248.5

243.5 *

Average flow rate (M³/hr)

6.20

5.66

5.27

4.00 *

* Lower WABT and average flow rate due to lower throughput caused by reduced market demand in 2024.

Table 1

Catalysis 2026