Coprocessing of Alternatives Feeds in the FCC: a point of view with Melissa Clough Mastry, BASF

Ahead of ME-TECH 2023, we caught up with Melissa Clough Mastry, Global Director of Technology and Technical Services at BASF Refining Catalyst Group to find out which alternative feeds are suitable and available for co-processing in FCC units, how the process differs from conventional FCC operations and how BASF helps refiners with its technologies.

1. What are the available alternative feeds suitable for co-processing in FCC units and can the products be classified as a “drop-in” solutions?

There are a wide variety of possible feeds that refiners are looking to co-process or have already coprocessed in an FCC. The decision of which feed to use comes down to availability, cost, incentive (such as RIN credits in the United States or how close does an alternative feed type bring a refinery to meeting the GHG reduction target laid out by the EU Renewable Energy Directive, or the premium placed on product produced), and impact on FCC operation and product yields. We can think of a number of broad categories to describe alternative feeds, including vegetable oils, waste oils and fats, and pyrolysis oil made from waste products. Waste products can include (in varying quality and quantity) sorted plastics, mixed plastic waste, biomass waste, or municipal solid waste. Depending on the amount of alternative feed co-processed, typically expressed as a % versus traditional fossil fuel, and the quality of the oil, any of these could be considered as a drop-in. This especially applies to vegetable oils, about which there has been a lot of knowledge shared in the open literature. These tend to be the most similar (in terms of contaminants, hydrogen and carbon content) to traditional fossil fuels. For certain types of plastic pyrolysis oils, these can also be considered drop-in solutions, especially those originating from sorted plastic waste, and especially those consisting mostly of polyolefin plastics. For the rest, it comes down to the contaminant, hydrogen, and oxygen levels, among other variables, to determine if it can be a drop in or if further considerations are required. 

2. How does co-processing alternative feeds differ from conventional FCC operation? What are the main challenges identified and will producers be able to overcome them? 

The answer to this question is unequivocally "it depends". That being said, we can define some rules of thumb based on recent experience. The answer depends on the feed quality and characteristics, how much a refiner plans to co-process alongside the traditional fossil feed, and what goals the refiner has in mind. Generally, vegetable oils are very easy to process in an FCC but can bring along some oxygen which will go to non-valuable water or CO2. Plastic waste can range from easily crackable to being very difficult to crack. In the case of polyolefin rich plastic waste, these tend to be easy to crack and contain lower amounts of contaminants. Other plastic waste, especially those containing PVC and PET, bring unique challenges. PVC for example can bring high amounts of chlorides, which increase coke and hydrogen by reactivating contaminant nickel and can cause major problems downstream the FCCU in the main fractionator. PET brings difficulty to manage oxygen leading to low-value products. Biomass waste varies to an even greater extent, given the richness in possible starting materials. In general, they contain high amounts of con carbon, contaminants, water, and oxygen. Municipal solid waste is highly variable, but depending on the pre-processing done by the pyrolysis oil producer, these can be managed while paying attention to water, contaminant, and con carbon contents.  

There are hardware solutions refiners can consider investing in to mitigate some of these issues, but there are steps that can be taken with an FCC catalyst to improve performance with these feeds. For example, it is important to be aware of how much contaminant (such as Cl or Na) is being introduced with the fresh catalyst - lowering this number increases the amount that can come in with feed. Similarly, the activity of the catalyst could be increased through a higher surface area or rare earth to counteract the impact of contaminants. FCC catalysts can also be designed with vanadium or nickel passivation technologies - these increase activity and lower coke yield which can further increase a refiner's flexibility to process newer, more challenging feeds. In the case of product yield shifts, especially between gasoline and LPG, a refiner should consider a catalyst change to maintain desired yield patterns. This would include adding or removing an olefins' additive or changing the acid site density of the base catalyst. 

3. If an FCC is considering to co-process alternative feeds, what are some steps they can take to prepare themselves?

The process should start with many questions. One of the first questions to ask is about the quality of the oil - for this, we always suggest refiners to work very closely with their alternative feed supplier, including asking for a full set of specifications, including water content, con carbon, traditional contaminants, more unique contaminants like special alkali metals, chlorides, and feed distillation data. Furthermore, understanding what exactly went into the oil, in the case of pyrolysis processes, helps. For example, if the pyrolysis oil is of plastic origin, what type of origin was fed into the pyrolizer? Was it a single plastic stream, was it sorted plastics, is it mostly polyolefins, does it contain any PVC and/or PET? If the pyrolysis oil is of biogenic waste origin, what type of crops/plans/mass was fed into the pyrolizer? This can give an idea of the content of lignan and/or cellulosic material that went into making the oil. The next question revolves around understanding what others have done with this unique oil, if anything. In the cases of vegetable oils, there is much published work that can help guide refiners to answer some of the initial questions. In cases of under-studied oils, we always suggest refiners to prepare by undertaking some lab testing, whether that involves analytical/characterization and/or performance testing at varying ratios of alternative feed versus traditional feed. This can give an idea of the impacts the oil can have in the FCC and can help define what is possible in terms of co processing %. Additionally, simulations and calculations should be done to predict contaminant content on catalyst, and impacts on conversion and yields, in case lab performance testing was not done. Lastly, the refiner should understand what the contaminants, con carbon, and feed characteristics/distillation will do to the catalyst performance - and the refiner should take this information into consideration and decide whether a catalyst change or tweak is necessary to combat the incoming changes.

4. What FCC catalysts are available for co-processing in an FCC?

We have had refiners using various BASF technologies co-process a variety of different alternative feeds. All of them have done this with their existing catalyst technologies. In most cases, the catalysts came from our resid portfolio to deal with the contaminant metals and heavy molecules, and in other cases with cleaner feeds, the catalysts came from our VGO portfolio. More generally, as it stands today where most (albeit not all) are considering co-processing in the 1-15% range, we find that today's catalysts are more than equipped to handle the contaminants, yield shift pattern, and con carbon content of today's alternative feeds. We might see the use of advanced metals trapping technologies such as Boron Based Technology and Valor increase in the near future as the trend continues. This landscape can change in the future when refiners push above the 15-20% and even look to more adventurous alternative feeds with higher contaminants and a higher degree of differentiation versus today's oils.

?? Would you like to hear more?

BASF is one of the official sponsors of the upcoming ME-TECH, the Premier Technical Downstream Event for Refiners & Petrochemicals, taking place on 16-18 May in Dubai.

Don’t miss the opportunity to meet and network with the BASF team and learn more about all the challenges and benefits of alternative feeds' coprocessing in FCC units.

?? Check out the full conference's agenda: ME-TECH Agenda