Advantages of SPSR SPSR units have many advantages. They require far less catalyst and feed. They provide excellent temperature con - trol and reproducible reactor loading because the diameter of the extrudates is slightly smaller than the reactor diam- eter. In addition, extrudates automatically align as a string of extrudates which, in combination with the narrow reac- tor, avoids maldistribution of gas and liquid over the cata- lyst bed, thereby eliminating catalyst bed channelling and incomplete catalyst wetting. When an inert diluent is used, it can be introduced after catalyst pellets are loaded over the full length of the tube, resulting in embedded extru- dates but not going between them. Due to the size and feedstock consumption of such small- scale reactor systems, it becomes feasible to implement these in a compact platform while still operating under rel- evant conditions. This enables not only the testing of mul - tiple options under identical conditions but also allows for a true replication of tests. This increases data quality and allows the estimation of confidence intervals, thus improv - ing over the more common ‘single point’ tests. Results Four experimental conditions were used to evaluate the catalysts during each run, in addition to the initial lining-out step after the sulphiding of the catalysts. The following sec - tion presents a summary of the main results obtained dur- ing the evaluation test for comparing catalyst performance with the three levels of LCO: 15%, 30%, and 45%. Hydrogen consumption Gas and liquid effluent were measured and analysed during each testing condition (using a specific feed and tempera - ture). GC analysis of the gas effluent (combined with the use of Helium as an internal standard) allowed for estima- tion of hydrogen consumption at each operating condi- tion. Figure 5 shows the hydrogen consumption results for different catalyst designs evaluated using an SRGO feed blended with different amounts of LCO.
Loading scheme
R1 R2 R3 R4 R5 R6 R7 R8
Top beads bed
Catalyst bed
Bottom beads bed
Bottom frit
Catalyst (CoMo)
Catalyst (NiMo)
Figure 4 Reactor loading schemes
on top of each other, forming a continuous bed of catalyst with the maximum possible length-to diameter ratio (see advantages of SPSR in the following discussion) to ensure minimal axial dispersion and the closest behaviour to plug flow. Also, some inert ceramic beads (Zirblast) were used to fill empty spaces between the catalyst particles and the reactor walls (within the catalytic bed) and to provide a top layer of fines for the distribution and mixing of the gas and liquid feeds. As a best practice, all catalysts were pre-weighed inside the nitrogen glove box after drying to ensure the most accurate catalyst weights before the reactor loading, with a maximum weight deviation (target vs measured) of 0.3%. For this study, the average deviation was only 0.21%. As shown in Figure 4, different catalyst configurations were tested during the experiment to determine the opti- mum one. Each catalyst stacking and rationing strategy yielded different levels of relative volume activity (RVA) and total hydrogen consumption. A balance between cat - alyst activity and hydrogen consumption can be achieved by strategically stacking and rationing both CoMo and NiMo hydrotreating catalysts into a constant reactor volume.
900
SRGO + 30% LCO
800
SRGO + 15% LCO
700
SRGO + 15% LCO
SRGO feed
600
500
SRGO + 45% LCO
400
300
200
100
0
50
100
150
200
250
300
350
400
450
500
Elapsed run time , h
CoMo
CoMo/NiMo/CoMo
NiMo
NiMo/CoMo
Figure 5 Hydrogen consumption trend
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Catalysis 2023
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