PTQ Q3 2022 Issue

four decades has targeted improving the performance of distillate hydroprocessing units around the world. In 2013, Topsoe researchers commercialised the proprietary HyBRIM technology based on an improved production technique that maximises the nickel promotion of molyb- denum slabs. This resulted in higher hydrodesulphurisa- tion (HDS) and hydrodenitrogenation (HDN) activity. In recent years, HyBRIM technology was further improved, and a new generation of premium HyBRIM catalysts was commercialised. For the HCU, considering the varying nature of VGO resultant from varying crude sources and the severe nature of HCGO, Topsoe designed a staged activity load utilising both first-generation HyBRIM catalysts and the latest pre - mium HyBRIM catalysts. This approach ensures that the relatively easy sulphur and nitrogen species are removed in the first three beds. The final bed with premium HyBRIM catalyst treats the most sterically hindered sulphur and nitrogen species and maximises aromatic saturation in the pretreat reactor (see Figure 9 ). This staged activity load has demonstrated deep HDN of the severe feedstocks processed in the HCU and has three- pronged benefits for the hydrocracking catalysts:  Low organic nitrogen slip ensures low inhibition of acid sites in the first-stage hydrocracking catalysts. Hence, the full activity potential of first-stage catalysts is realised. This helps manage activity balance between the two stages.  Ar omatic compounds are difficult to crack. Once they are saturated to naphthenes in the pretreat reactor, they are more easily and selectively cracked in the downstream hydrocracking reactor. This improves volume swell and middle distillate yield.  Saturation of aromatics helps improve product proper- ties such as jet fuel smoke point and diesel cetane inde x. Hydrocracking catalysts Topsoe manufactures its own hydroprocessing catalysts, including its own zeolites and aluminas, which are key carrier components in hydrotreating and hydrocracking catalysts. This allows for full control of the entire catalyst manufacturing process. The performance of hydrocrack- ing catalysts depends on several factors, including zeolite types, zeolite porosity, zeolite acidity, and acid site proxim- ity. Topsoe also controls the production of metal-support relationships and this, coupled with tight quality control in manufacturing, enables catalysts to achieve desired perfor- mance. This understanding is further enhanced by the use of advanced pilot plants and analytical tools. As Figure 10 shows, Topsoe’s base metal hydrocrack- ing portfolio offers three main types of catalysts. The red series offers maximum hydrogenation to enhance volume well, maximise naphtha and kerosene yields, and upgrade UCO for base oil or steam cracker services. The blue series offers a balanced high yield of middle distillates and opti- mised diesel cold flow properties. The D-sel series offers excellent yields of middle distillates in both kerosene and diesel ranges. From this wide portfolio, selecting the optimal combination

TK-939 D-sel™

TK-926

TK-921

TK-949 D-sel™

TK-925/TK-927

TK-931

TK-943

TK-969 D-sel™

TK-947

TK-941

TK-951

TK-961

TK-971

Activity

Figure 10 Topsoe catalyst portfolio

of hydrocracking catalysts for maximising HCU profitability required the following considerations:

 Maximise middle distillate yield  Control HPNA in the second stage

 Operate at max conversion for four years’ cycle length  Provide flexibility to increase naphtha in response to changes in market demand  Provide flexibility to navigate operational constraints that limit reactor temperatures and conversion. Four options comprising the following catalysts were evaluated: Cat A: Catalyst from the D-sel series showing high middle distillate selectivity Cat B: Amorphous catalyst showing high middle distillate selectivity Cat C: Catalyst from the red series having higher activity than Cat B Cat D: Catalyst from the red series having higher saturation activity than Cat C. From the previous comparisons and listed in Table 4 , it becomes clear that there is a trade-off between boosting middle distillate yield and controlling HPNAs over the entire cycle. It is important to operate the HCU in a stable and reli- able way over a full four-year cycle, preventing unplanned shutdown or mid-cycle skim. Hence, it was decided to evaluate options 3 and 4 in more detail. Among these two options, option 3 was selected, as this catalyst combination has the following advantages:

Comparison of different catalyst systems from Topsoe’s hydrocracking catalyst portfolio

Option 1 Option 2 Option 3 Option 4

1st stage HC catalyst 2nd stage HC catalyst

Cat A Cat A

Cat A Cat B

Cat A Cat C

Cat A Cat D

Overall middle distillate yield BASE

Control HPNA in 2nd stage Flexibility in operation over a complete four-year cycle

BASE

- -

+ +

Flexibility to increase naphtha BASE

Table 4

PTQ Q3 2022