Filtration and degumming Modification: Install filtration systems to remove impurities and solids from feedstocks like vegetable oils. Relevance: Impurities can lead to catalyst poisoning and operational issues. For instance, the presence of phospho - lipids in crude vegetable oils can hinder catalytic activity. Heating and viscosity reduction Modification: Preheat feedstocks to reduce viscosity and improve flow characteristics. Relevance: Heavier feedstocks, like used cooking oils, may benefit from preheating to allow for better mixing and improved processing in the FCC or hydrotreater. Mixing and emulsification Modification: Use emulsification techniques to create a homogenous mixture for coprocessing. Relevance: Certain feedstocks may not blend well with conventional feeds without emulsification, leading to incon - sistent processing and lower yields. These modifications are integral for optimising the copro - cessing of renewable feedstocks in FCC and hydrotreaters. Each type of alternative feedstock may require specific adaptations in both equipment and processing conditions to maximise yield and performance. By implementing these changes, refineries can better integrate renewable feed - stocks into their existing processes, thereby enhancing sustainability while maintaining economic viability. A Darrell Rainer, Global FCC VGO Specialist, darrel. rainer@ketjen.com , Jon Strohm, R&D advisor, james. strohm@ketjen.com, Cliff Avery, Global FCC Process Advisor, cliff.avery@ketjen , Ketjen Modifications necessary to enable renewable feedstock inte - gration within existing operations are dependent primarily on the differences in feed properties compared to conventional petroleum feedstocks. Renewable feedstock properties related to increased and new contaminant levels, thermal stability and reactivity, and high oxygen content are gener - ally the main factors influencing operational, process, and equipment modifications. Based on chemical composition
and feedstock properties, renewable feedstocks for copro - cessing can be summarised in two categories. The first category is fats, oils, and greases (FOG), which are triglycerides from edible oils, non-edible oils, used cooking oil (UCO), and animal fats. The second category is bio-oil derived from either pyrolysis or hydrothermal lique - faction of agricultural, forestry, municipal wastes, and other lignocellulosic materials. Common to both FOG and bio-oil is the potential for high levels of various contaminants, particularly alkali and alka - line earth metals, phosphorous, chlorine, and silica. High levels of metals can create corrosion concerns and impact catalyst activity and lifetime. The most difficult of the FOG group to treat would be UCO with elevated chlorides, acid - ity, metals, and other contaminates. Crude FOGs are the next most challenging, with elevated metals and contaminates. UCO, crude FOGs, and bio-oils will exhibit elevated contaminant metals and chlorides with attendant corrosion concerns that may require lining storage tanks and selection of corrosion-resistant metals for process equipment and piping. These materials are not commonly processed at this time. They are not compatible with fossil fuels and have stability concerns. They will have extremely high water (~20 wt%) and oxygen (~20 wt%) levels with extremely high metals and impurities. Since they do not compete with food, they are considered substan - tially more desirable as a renewable feedstock. Since bio-oils are far less commonly used, this response will focus primarily on the FOG effect on hardware changes/ additions. FCC unit Shipping/receiving and storage: Typically, feedstocks are delivered by ship or truck and should be diverted to a sepa - rate storage tank. Time-dependent feed quality degrada - tion is a greater concern for FOGs and bio-oils relative to conventional feedstocks (a storage life of three months is usually considered acceptable, depending on ambient tem - perature and specific feedstock characteristics). Ageing of FOGs can result in increased fatty acid content, leading to higher acidity and corrosion concerns, while ageing of bio- oils can result in gumming and fouling of process vessels
Renewable source Edible and non-edible oils Used cooking oil (UCO) Animal fats (tallow) Renewable source Agricultural wastes Forestry wastes Municipal wastes Other lignocellulosic materials
Main hydrocarbon types Natural oils and fats, virgin or processed: Tryglycerides and fatty acids Main hydrocarbon types Products from pyrolysis or hydrothermal liquefaction: Unsaturated compounds but also high oxygenates
Characteristics Known and predictable composition Some impurities present: Na, K, Si, P Characteristics Not compatible with fossil fuels and stability concerns No competition with food High impurities present: O, alkalis, Ca, Fe, Mg, P, Cl
FOG
Flue gas
Bi o -oils
Steam
Steam
Air
Common catalytic requirements to successfully process these feeds: Catalyst technologies with high accessibility and materials resistance Control of deoxygenation pathways to minimise impact on product slate and FCC unit operations
Feed
Steam
Figure 1 Overview of FCC unit renewable coprocessing feed options
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PTQ Q1 2025
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