PTQ Q2 2022 Issue

Feed to diesel hydrotreater used to perform catalyst testing



Feed to diesel hydrotreater (50% SRGO/50% cracked feeds)


Density 15°C, kg/m³

903.5 1.2587 965.9

Sulphur, wt%

Nitrogen, ppmwt

Bromine Number, gBr/100 g



Total aromatics, wt% Mono-aromatics, wt% Di-aromatics, wt% Tri-aromatics, wt% Poly-aromatics, wt%

47.7 19.1 23.9




Simulated distillation (SimDist) 10%, °C

237 417 454

95%, °C FBP, °C


Table 2

Pos. 1 ID 4.80 mm

Pos. 5 ID 4.80 mm

Pos. 8 ID 4.80 mm

Pos. 11 ID 4.80 mm

Pos. 14 ID 4.80 mm

a line-out period and start-of-run (SOR) temperature conditions. The experiments were designed in such a way that sulphur effluents at dif - ferent conditions ranged from 10 to 50 ppmwt. The feed for this test was chosen to test the catalysts with very high concentrations of nitro- gen and aromatics. For this reason, the gas-to-oil ratio (GTO) was kept at a relatively high level to ensure no more than 30% of the hydrogen introduced was consumed. This precaution was taken to mitigate the concerns of catalyst deactiva- tion due to operating in a hydrogen starved regime. Excel rejuvenation enables the recovery of equivalent activity to fresh. To detect activity differences of less than 10% in a laboratory test, every aspect of the test – from reac- tor loading, temperature control, equal feed distribution between reactors to product sample prepara- tion and analyses – has to be carried out with utmost care to minimise all possible errors. For accuracy, it is crucial when comparing catalyst activities to have a good mass bal- ance throughout the experiments. In this case, mass balances for all cata- lysts compared were in the range of 99.5 ± 1%. Results and discussion The fresh and rejuvenated catalysts were tested in parallel at various process conditions while focusing on the parameters below after the hydrotreating reaction:


SiC inert lling

SiC inert lling

Fresh NiMo

Excel NiMo

Excel CoMo


Isotherm zone start

Isotherm zone end

Figure 1 Loading configurations of fresh and rejuvenated catalysts

Loading configurations of fresh and rejuvenated catalysts


Catalyst type Fresh NiMo

Loading configuration

Pos. 1 Pos. 5 Pos. 8 Pos. 11 Pos. 14

100% 100%

Excel NiMo

Excel NiMo/Fresh NiMo Fresh NiMo/Excel CoMo Excel NiMo/Excel CoMo

30%/70% 70%/30% 70%/30%

Table 1

The catalyst volume employed was 2 mL per reactor, with catalyst stacks as small as 0.6 mL used for reactors loaded with 30% rejuve- nated and 70% fresh catalyst. The catalysts were tested as full-bod- ied extrudates, which were sorted by length to select only those with a length shorter than 4mm. The inner diameter of the reactors was 4.8mm. The feed, a blend of SRGO (50 wt%), LCO (25 wt%), and CGO (25 wt%) from a European refinery die -

sel hydrotreater, was used to carry out catalyst testing (see Table 2 ). The experiments were conducted at a hydrogen partial pressure of 75 barg, LHSV = 1.00 h -1 and H 2 /oil = 609 Nm 3 /m 3 using four different temperatures (see Table 3 ). After a dry-out step at 115°C for four hours, a common wetting and sulphiding procedure was imple- mented, where dimethyl disul- phide (DMDS) was added (2.5 wt%) to straight-run gasoil for catalyst activation. This was followed by

Operating conditions used to perform catalyst testing


ppH 2 , barg



2 /oil, Nm³/m³

Temperature, °C


6 7 8 9




358 361 363 365

Table 3

50 PTQQ 2 2022

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