Catalysis 2023 Issue

each temperature adjustment was 24 hours. At least one liquid sample was collected at the end of this period, while the composition of the gas effluent from each reactor was anal- ysed sequentially using a GC analyser (Agilent 7890B). The liquid sampling time was eight hours, so the amount of liquid collected was around 5 ml. The total concentration of sulphur and nitrogen was measured on the liquid product samples using an Xplorer TN/TS analy- ser according to the standard method ASTM D2622.

MFC

Diluent gas distribution

Gas 1

MFC

Gas 2

MFC

Mixed gas feed distribution

Gas 3

MFC

Gas 4

MFC

Active liquid distribution (ALD) system

Gas 5

MFC

Feedback

Coriolis

Reactors

Low P N

Liquid feed

Heated blocks of 4 reactors

All the catalysts evaluated were tested at the same tem- perature during each condition to compare their performance. The results obtained at the beginning of this test indicated some over-treatment of the feed (product S & N below the detection limit), so the tem- perature was reduced sequen- tially, requiring a longer time for stabilisation of the catalyst activity. The temperature program is graphically presented in Figure 2. Equipment, feedstocks, and reactor loading The testing program was conducted in a 16-parallel fixed bed reactor system with a reactor diameter of 2.0-2.6 mm. Figure 3 shows a schematic overview of the 16-parallel reactors pilot plant. This unit employs Avantium’s propri- etary Flowrence technology, which enables tight control of process conditions – temperature, flow rates, and pressure.2 Both the SRGO + LCO liquid feeds and the hydrogen feed gas were equally distributed to the 16 reactors. The pres- sure of each channel was measured before and after the catalyst bed using electronic pressure sensors. Based on these measurements, the reactor pressures were individu- ally controlled to ensure equal process conditions. Feedstocks The feeds used during the test consisted of different blends of SRGO and LCO obtained from the feed of the diesel hydrotreating unit at the customer’s refinery. Around 5 litres of three different feed blends were prepared by mix - ing SRGO and LCO in different proportions (15 vol% LCO, 30 vol% LCO, and 45 vol% LCO). The properties of the feed blends used during the test are presented in Table 1 . Catalyst loading The catalyst loading schemes were based on the commer- cial operation of diesel hydrotreating units. Four catalyst configurations were loaded in duplicates in eight reactors, N PIC

Pressure controller

PIC

Vent

200˚C

Vent

2nd analyser

Cooling tray 10–80˚C

Euent stove (max 120˚C)

Figure 3 Schematic representation of the Avantium pilot plant with 16 parallel SPSRs

as presented in Figure 4 . The amount of catalyst loaded in each reactor (2.0 mm internal diameter) was based on the weight of catalyst required to fill a compact bed of the cata - lyst, so the required weight of catalyst was calculated using the Compact Bed Density (CBD) according to Equation 1:

Weight Catalyst (g) = Cat. volume target (ml) * CBD ( g )

(1)

The targeted volume of catalyst bed was 0.6 ml for all the reactors. The actual bed length (catalysts loaded in a single string of pellets stacked on top of each other) for the reac- tors was around 33 cm. The total number of catalyst par- ticles loaded into each reactor was around 60. No crushing, sieving or other structural change was performed on the catalyst particles before loading. The catalyst particles were carefully loaded into the reactors following Avantium’s pro- prietary single-pellet string reactor (SPSR) loading. Here, the catalyst extrudates are vertically aligned and placed It is important to evaluate the implications of introducing more LCO in diesel hydrotreating units and effectively evaluate the impact on HDS conversion and hydrogen consumption

Catalysis 2023