Gasoline, diesel, and aviation fuel are still expected to dominate refinery markets to 2030; what reactor and catalyst systems will be the most effective in maximising fuel production?Jan-2024
Kurt du Mong, Zeopore Technologies, email@example.com
A key value creator in the refinery, specifically to yield fuels, remains the hydrocracker. These units feature multicomponent catalysts involving NiW or NiMo hydrogenation components supported on acidic zeolite/alumina carriers. These types of catalysts have gone through generations of remarkable developments, particularly with respect to the optimisation of the zeolite component.
Over the last decade, it has become clear that optimising the zeolite’s mesoporosity and macroporosity enables the control of the degree of cracking, thereby maximising the yield of fuels, which was demonstrated in a selection of refineries. However, thus far, mesoporous zeolite-based hydrocracking catalysts have been associated with inhibitive cost increases and lower conversion levels, limiting their widespread application.
Zeopore helps to overcome such limitations via a platform of affordable USY zeolites, yielding selectivity and activity benefits of a wide range of catalyst types and zeolite contents.
Zeopore’s mesoporised hydrocracking zeolites have recently been tested in a high throughput facility of a major refiner, generating up to 4 wt% more middle distillates at retained activity levels, generating $15 million more profit per average hydrocracker (see Zeopore press release: www.zeopore.com/post/zeopore-enables-breakthrough-in-hydrocracking-by-leveraging-zeolite-mesopore-quality)
Ioan-Teodor Trotus, hte GmbH, Ioan-Teodor.Trotus@hte-company.de
Which reactor system will be the most effective depends on multiple factors, such as the feed or feed mix to be converted, the actual fuel to be produced – diesel, gasoline, or aviation fuel – and, of course, on which reactors are already operating in the refinery.
For a refinery that aims to convert mainly crude oil with existing plants – be it hydrotreaters, hydrocrackers or FCC units – pilot plant tests will yield the most reliable results for choosing the right catalyst system.
The right catalyst system must show a reasonable level of activity and stability to maximise the duration of an operating cycle. This can be determined in pilot plant testing either as the start-of-run activity or by performing accelerated deactivation studies to estimate the mid-run or end-of-run activity.
At the same time, pilot plant testing will give information about the yields and properties of each fuel fraction, allowing one to feed a techno-economic model with actual plant data and make a like-for-like comparison of all the catalyst systems to be compared.
For a refinery aiming to co-process or process renewable feedstocks in existing equipment, a pilot plant test is even more important because it also allows the operator to see a new application in action before testing in a production unit. The number of industrial references for the conversion of renewable fuels is still relatively low compared to the number of references for the conversion of crude-derived feeds. Simply relying on models and paper studies is particularly risky in these cases, as such models still have relatively little data on which to build their estimates.
In short, the most effective catalyst – be it for hydroprocessing or FCC applications aimed at the production of fuels and the conversion of renewables – will most likely be the one that was determined by a pilot plant test.
Johanna Fernengel, Clariant Catalysts, Johanna.Fernengel@clariant.com
Besides topping upgrading, the key to maximising fuel production is the right balance of hydrocracking (HC), delayed coking (DC), and catalytic cracking (FCC), as this gives the highest flexibility in utilising nearly any crude source, including renewable sources. In particular, utilisation of the light olefins from the FCC off-gas with alkylation and oligomerisation with alternative concepts can give a higher flexibility, moving from sole gasoline focus towards distillates as potential diesel and jet blending components.
Pierre-Yves le-Goff, AXENS, Pierre-Yves.LE-GOFF@axens.net
For gasoline production, among the building blocks of the gasoline pool, we can mention isomerate and reformate. For reforming, maximisation of gasoline production is linked to a reduction of cracking while ensuring a stable operation. The addition of modifiers is one of the possibilities to reduce cracking; however, rigorous selection process is needed to ensure that stability and regenerability are not impacted. Axens, formerly Procatalyse, has been involved in such a field of expertise since the mid-1990s.
From a process standpoint, reduction of the pressure will improve the fuel production. However, such a reduction needs to be compatible with unit constraints (for example, pressure drop). To mitigate these pressure drops, a possibility is to move from a standard axial flow reactor to a radial flow reactor. Axens has already performed such modifications and has proprietary internals to improve gas distribution.
On the isomerisation side, depending on the octane target and feed composition, different schemes can be proposed. For example, if the feed is rich in C6 paraffin, the deisohexaniser (DIH) column can be implemented to maximise octane without selectivity debit. In addition, to reduce cracking, the use of high-activity catalyst is of paramount importance. Therefore, Axens process expertise with ATIS-2L catalyst provides the best combination for isomerisation unit optimisation.