Naphtha Hydrotreating Mode (Run 01)
Diesel Hydrotreating Mode (Run 02 at 60 bar and Run 03 at 120 bar)
Block 1
Block 2
Block 3
Block 4
Block 1
Block 2
Block 3
Block 4
R1 R2 R3 R4
R5 R6 R7 R8
R9 R10 R11 R12 R13 R14 R15 R16
R1 R2 R3 R4
R5 R6 R7 R8
R9 R10 R11 R12 R13 R14 R15 R16
LHSV = 2.0 I/I/h P = 15 bar Gas/oil = 50 NI/I T: 150˚C–190˚C (10˚C / 12h)
LHSV = 2.0 I/I/h P = 15 bar Gas/oil = 50 NI/I T: 200˚C–240˚C (10˚C / 12h)
LHSV = 4.0 I/I/h P = 15 bar Gas/oil = 50 NI/I T: 150˚C–190˚C (10˚C / 12h)
LHSV = 4.0 I/I/h P = 15 bar Gas/oil = 50 NI/I T: 200˚C–240˚C (10˚C / 12h)
LHSV = 0.5 I/I/h P = 60 bar T: 150˚C–190˚C (10˚C / 24h)
LHSV = 0.5 I/I/h P = 60 bar T: 200˚C–240˚C (10˚C / 24h)
LHSV = 1.0 I/I/h P = 60 bar T: 150˚C–190˚C (10˚C / 24h)
LHSV = 1.0 I/I/h P = 60 bar T: 200˚C–240˚C (10˚C / 24h)
NiMo
Blank
NiMo
CoMo
NiW
Blank
Figure 1 Experimental design
a specific order. This arrangement allows for the decoupling of axial dispersion phenomena from fluid dynamics, facilitat - ing ideal plug flow reaction conditions near the reactor inlet. For a more detailed understanding of the theory support - ing the use of single-pellet-string reactors, refer to the publi - cations by Moonen et al 1 and Ortega et al .² Test design The experimental programme aimed to evaluate the decom - position profile (by-products yield vs temperature) of the sulphiding agent TBPS at typical operating conditions used for the sulphiding of hydroprocessing catalysts. By studying the presence of the different by-products formed during the catalyst sulphiding, the objective was to identify the oper - ating conditions that favour the use of TBPS as a sulphid - ing agent without affecting the catalyst’s performance. The experimental programme for studying the decomposition of TBPS was conducted in three different runs performed at a testing unit with 16 reactors in parallel. The catalyst loading was carried out using three commer - cial catalysts: CoMo, NiMo, and NiW 1/16in trilobe extru - dates obtained from Topsoe. Before loading, no crushing, sieving, or other structural changes were performed on the catalyst particles. In all three runs, the reactors were operated under con - stant conditions for a duration of 12 hours. Following four hours of operation at each condition, the analysis of gas effluent commenced, proceeding sequentially from reactor 1 to 16. This sequential analysis spanned a total duration of four hours, allowing approximately 15 minutes per reactor. During this time, a single cumulative liquid sample was col - lected. This sampling procedure was repeated during the final four hours of operation for each testing condition, with the second sampling phase considered more representa - tive due to the longer stabilisation time. Run01 focused on simulating the sulphiding of a NiMo catalyst used in naphtha hydrotreatment. Each reactor block contained triplicate NiMo catalysts, along with a blank reactor filled with Zirblast. The reactor setup is illustrated in Figure 1 . Throughout Run01, a fixed pressure of 15 barg and a gas-to-oil ratio of 50 Nl/l were maintained. Sequential temperature changes occurred every 12 hours. In addition, the LHSV was varied by loading a smaller amount of cata - lyst in reactors 9 to 16 (blocks 3 and 4).
The test designs for Run02 and Run03 are also illustrated in Figure 1. Run02 and Run03 had identical testing proto - cols, except for the partial pressure of H₂ (60 bar in Run02, and 120 bar in Run03). Prior to introducing the liquid feed, the catalyst was heated from 50°C to 120°C at a constant heating rate of 15°C/h, with H₂ flowing at a rate of 4.7 NmL/ min/reactor. The temperature was then held constant at 120°C for two hours to ensure proper drying. Following dry - ing, the gas flow rate was reduced to 2.5 NmL/min/reactor, and the liquid feed was introduced at a flow rate of 16.7 mg/ min. This soaking step aimed to prepare the catalyst and was performed at a constant temperature of 120°C for five hours. Once soaked, the reactor’s pressure was increased to 60 bar of H₂ partial pressure for Run02 and 120 bar for Run03. The temperature was then adjusted to the setpoint for Condition 1 (150 and 200°C) at a rate of 15°C/h, which was maintained for all subsequent temperature adjustments. The reactors were maintained at a constant operating condition for 12 hours, similar to Run01. After four hours of operation at each condition, the gas effluent analysis was performed sequentially, starting with reactor 1 and conclud - ing with reactor 16. The total duration of the sequence for analysing all 16 reactors was four hours, with 15 minutes allocated for each reactor. Additionally, to assess the influ - ence of TBPS thermal decomposition, a set of four reactors (one per block) was filled with Zirblast (without catalyst) and treated and analysed under the same conditions as the reac - tors loaded with NiMo, CoMo, or NiW catalysts. These tests aimed to simulate the sulphiding of three differ - ent catalysts (NiMo, CoMo, and NiW) used in the production of ultra-low sulphur diesel (ULSD) under varying operating conditions. During the test, each reactor block maintained a fixed temperature for a period of 24 hours. For the first 12 hours, the gas-to-oil ratio was kept at 500 Nl/l, and then it was reduced to 250 Nl/l for the subsequent 12 hours, while all other operating conditions remained unchanged. Gas effluent samples were collected at each testing condi - tion, and two consecutive samples were analysed using the online GC. Liquid effluent samples were also collected during this period for the analysis of total sulphur content. TBPS by-product distribution online GC analysis The gas chromatography online analysis was conducted to identify and quantify various components in the gas effluent.
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PTQ Q4 2024
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