Catalysis 2024 Issue

FCC co-processing of biogenic and recyclable feedstocks: Part I

Refinery sustainability drivers predicate a focus on renewable and recyclable feedstocks and the challenges and solutions for co-processing them in FCC units

Jon Strohm, Darrell Rainer, Oscar Oyola-Rivera and Clifford Avery Ketjen

T o adapt to the world’s energy and material transition, refiners and chemical manufacturers are challenged to rethink their processes to accommodate the use of renewable and recyclable (R&R) feedstocks. Depending on the installed assets, available feedstocks, and local incen - tives and regulations, different R&R feedstocks may be selected, and different routes towards valorisation may be taken. A number of these strategies are illustrated in Figure 1 , where the crucial role of catalytic processes such as FCC and hydroprocessing is apparent. We can follow the industry trends by reviewing the publicly available International Sustainability and Carbon Certification (ISCC) requests. Ketjen categorises the R&R feedstocks to the FCC under the three headings described in Figure 1. These categories are based on their source,

hydrocarbon types, general characteristics, and the overall process and catalytic challenges for the FCC unit. Fats, oils, and greases (FOG) are triglyceride based, with plant and animal oils as the source. Of the FOGs, used cooking oil (UCO) is the most difficult to process due to the decomposition and added metals from cooking/frying. Crude or unprocessed vegetable oils may have elevated metals if not refined (bleached, degummed). FOGs are a high molecular weight (MW) paraffinic/olefinic oil. The second classification is waste plastic oil (WPO). The WPO, with a boiling point in the naphtha/diesel range and the K-factor dependent on the source, is produced by lique - faction/pyrolysis of some type of polymer. This product will exhibit a boiling point in the diesel range, from paraffinic to aromatic, depending on the source.

Primary conversion

Upgrading

Valorisation

Hydroprocessing ReNewFine

FOG

Transportation fuels

Waste plastics

Steam cracker

WPO

Monomers & chemicals

FCC ReNewFCC

Liquefaction

Municipal solid waste

Bio oil

Biomass

FOG

Bio-oils

WPO

Sources Edible/non-edible oil Used cooking oil Animal fat (tallow) POME byproducts/off-spec biorenewable diesel Main HC types Natural oils and fats Triglycerides and fatty acids Characteristics Known and predictable composition ~8 - 12% oxygen content Some impurities: Na, K, Si, P

Sources Agricultural wastes Forestry wastes Municipal wastes Lignocellulosic materials Main HC types Products from pyrolysis or HTL Unsaturated and oxygenated compounds Characteristics Incompatible w/fossil feeds and high free water >20 wt% oxygen content High concentration of impurities: Alkalis, Ca, Fe, Mg, P, Cl

Sources

Waste plastics End-of-use tyres/rubber Electronic wastes Main HC types Products from pyrolysis or HTL Olefins/aromatics/paraffins Characteristics Highly variable Storage stability concerns High concentration of impurities: Halides, a lkalis, P, Si, Mg, m etals

Figure 1 Integration of renewable and recyclable feedstocks for the production of chemicals and transportation fuels, highlighting the role of hydroprocessing and catalytic cracking in valorisation within existing refining and petrochemical assets (top of figure). Summary of the main categories feed options for co-processing, categorised by source of feedstock, main hydrocarbon types, and characteristics as it pertains to catalytic and process challenges for hydroprocessing and FCC co-processing

Catalysis 2024