Pilot plant studies of lubes hydrotreating catalysts
Studies of catalysts for hydrotreating lubricant base oil delivered similar results from conventional and high throughput pilot plant
For a commercial evaluation of two different catalyst loading schemes for a lubricant base-oil hydrotreater two pilot plant studies were executed.
One pilot plant is a conventional unit with a single-reactor pilot and an available catalyst volume of above 500 cc. The second is an Flowrence® XR unit with 16 parallel single-pellet-string reactors (SPSRs) system, which ensures stable and highly accurate control of gas flow, liquid flow, and pressure across all reactors. Performance data like hydrogen consumptions and liquid product properties were determined independently per reactor. For this, the products from each SPSR were collected separately and various offline analysis performed, e.g., distillation, sulfur, nitrogen, and aromatics.
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Due to excellent hydrodynamics of the SPSR and sophisticated process control, the Avantium unit achieved high reproducibility resulting in average deviations of less than 0.2 wppm for hydrodesulfurization (HDS) and hydrodenitrogenation (HDN) across the quadruple reactors with the same loading scheme.
Results from the conventional pilot plant corresponded closely to results from the Avantium pilot plant. For Catalyst System A, the relative average deviations were less than 1% for HDS and HDN. For Catalyst System B, all relative HDS deviations two of three HDN deviations were less than 1%.
These observations indicate transitively that the Avantium unit is a suitable alternative to the conventional pilot plant for the customer’s lube oil hydrotreater. Moreover, due to the small scale of testing, safe operation can be accomplished in a laboratory setting which would be difficult to achieve with the same number of reactors at a conventional scale. Furthemore they require far less catalyst and feed, provide excellent temperature control and reproducible reactor loading. In addition, extrudates automatically align as a string of extrudates which, in combination with the narrow reactor, avoids maldistribution of gas and liquid over the catalyst bed, thereby eliminating catalyst-bed channeling 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 extrudates while not going between them.
Comparison of the results with the customer single-reactor unit
The customer executed a similar study in a larger scale without duplications. The Figures here show a comparison of the results from these tests and indicate that results from the Avantium unit are in line with client data obtained from much larger scale reactors. Results from the two pilot plants corresponded closely. For Catalyst System A, average deviations were less than 1% for HDS and HDN. For Catalyst System B, all HDS deviations and two of three HDN deviations were less than 1%.as quantification.
Two catalyst loading schemes were evaluated for a change out in a commercial lubricant base oil hydrotreater. The tests were executed in a unit with single-pellet-string reactors (SPSRs) from Avantium as well as in a conventional pilot plant. The comparison of both units showed that the small-scale results are well in line with the conventional technology, especially for HDS and HDN. The study demonstrated several advantages for SPSR systems, including the following:
· Avantium systems can replicate results from conventional pilot plants
· A feed far heavier than diesel can be handled and processed reliably
· Different catalyst schemes can be tested simultaneously at several sets of process conditions
· Replication provides the means for statistical evaluation of data
· Hydrogen consumption can be determined with high repeatability
With the additional information about the LHSV within the same testing time, the customer could evaluate more economic options and ultimately make a better decision.
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