NARTC 2026 Conference Newspaper

NARTC 2026

Biofeed FCC co-processing and maximising low-carbon propylene yield

R González and S Brandt W. R. Grace

Pilot plant testing will help understand the magnitude of changes in oxygenates and water, CO, and CO₂ yields. In addition, a close collaboration with the catalyst sup- plier will help discover areas of concern and monitoring requirements. Conclusion The drive towards decarbonisation and the energy transition is prompting the refining industry to adopt a new way of thinking, reconsidering value chains and associated process schemes. The importance of the FCC process in refining, coupled with its high flexibility, makes it a key candidate for adaptation to new opportunities that are emerging. Besides lower-carbon-intensity trans- portation fuels, one of the target prod- ucts of the FCC process is propylene. The demand for low-carbon-intensity and bio- derived polyolefins is increasing, and the adaptability and sophistication of the FCC process are ideal conditions to contribute meeting the demand for bio-derived poly- mers. Grace is supporting several refining customers on their paths to decarbonise the FCC unit’s operation and products. In addition, its expertise in product purifica- tion by adsorbents or hydrogenation and downstream processing to polyolefins is providing solutions for the new challenges that can arise with the co-processing of bio-derived feed streams. References 1 Lee, G., Brandt, S. and Holder, D., Maximising renewable feed co-processing at an FCC, PTQ , July 2023. 2 Peréz, E, et al., Decarbonize the FCCU through maximizing low-carbon propylene, Hydrocarbon Processing , March 2024. 3 Cipriano, B., Cooper, C. and Brandt, S., Paving the way to low-carbon propylene from the FCC unit, Decarbonisation Technology , November 2023. 4 Gonzalez, R., Bescansa, M., Fernandez, A., Mena, A. and Rivas, C. Defossilizing the FCCU via coprocessing of biogenic feedstocks: From laboratory to commercial scale, Hydrocarbon Processing , July 2023. 5 Riley, B., Brandt, S. and Bryden, K. Co-processing of bio-based feedstocks in the FCC unit, Decarbonisation Technology , August 2022. 6 den Hollander, M., Wissink, M., Makkee, M., Moulijn, J.A. Gasoline conversion: reactivity towards cracking with equilibrated FCC and ZSM-5 catalysts, Appl. Catal. A: General , 223 (2002), 85. 7 Seiser, R., Olstad, J. L., Magrini, K. A., Jackson, R. D., Peterson, B. H., Christensen, E. D. and Talmadge, M. S. Coprocessing catalytic fast pyrolysis oil in an FCC reactor, Biomass and Bioenergy , 2022. 8 Harding, R. H., Zhao, X., Qian, K., Rajagopalan, K. and Cheng, W.-C. Fluid catalytic cracking selectivities of gasoil boiling point and hydro- carbon fractions. Industrial and Chemical Engineering Research , 35 (1996), 2561. Contact: stefan.brandt@grace.com

With the refining industry’s strive towards decarbonising operations and pivoting towards the production of lower-carbon- intensity products, new challenges and opportunities arise. Close collaborations between partners are vital to the adoption of existing refining industry assets and ensuring rapid progress in the world’s jour- ney towards lower CO₂ emissions.¹ Propylene is one of the main petrochemi- cal products from crude oil refinery opera- tion. While current global market conditions for propylene are suppressed, C₃= demand is projected to grow by an annualised 4% through 2030, which will drive demand for fluid catalytic cracking (FCC) propylene accordingly.² Propylene produced by FCC already has a favourable carbon intensity compared to other on-purpose processes.³ Additionally, the application of ZSM-5- containing technology to increase FCC pro- pylene yields is preferred because of its neutral impact on the heat balance of FCC units and therefore Scope 1 emissions. In addition to its favourable carbon intensity, the carbon impact of FCC C₃= can be further reduced by the use of ZSM- 5-based technology and/or co-process- ing biogenic feedstocks to the FCC unit. Grace has been partnering with a num- ber of refineries globally to contribute to assessing the opportunities and risks of co-processing bio-derived feeds, as well as closely monitoring commercial trials and servicing continuous operation. 1,2,4,5 FCC proceeds via a β -scission mecha- nism on the active sites of the catalyst ( Figure 1 ).⁶ The end product of β -scission is C₃=. To further reduce the carbon inten- sity of the FCC C₃= co-processing, bio- derived feed streams to the FCC unit can be considered.³ The higher the co-processing rate, the bigger the impact on the carbon intensity of the related FCC products. Assuming an equal distribution of renewable car- bon among the FCC products, the co-pro- cessing rate (mass-based) can be directly related to a reduction in carbon inten- sity; consideration of the oxygen content of the renewable feed source is required. The oxygen content in the renewable feed is mostly converted to water, carbon mon- oxide (CO), and CO2 yields. It can be esti- mated that, considering a co-processing rate of 10 wt% renewable feed with an oxygen content of about 10 wt% (in the range of many seed oils), the carbon inten- sity of the resulting C₃= would reduce by 9%. The ultimate impact of co-processing renewable feed components on the yield structure is likely to be different to this the- oretical mass balance approach. However, this must be determined in FCC unit pilot plant testing and commercial applications, as they depend on the fossil feed type, unit conditions, and FCC catalyst proper-

Catalyst (Acid site)

H +

H H H H

Protonation

H H H H

Carbenium ion

H H

β-scission

H H H H

Olen product

Figure 1 Catalytic cracking reaction mechanisms²

mental yield concept,⁸ it is estimated that palm oil yields 6-7 wt% FF C₃=, nearly dou- ble the yield of the fossil-based VGO in this particular case. While Figure 2 illustrates the potential increase in C₃= from renewable co-pro- cessing, challenges with co-processing should be considered. These challenges are often associated with the significantly higher oxygen content of the renewa- ble feed component relative to traditional feedstocks. Despite the absence of added hydrogen (H₂), the FCC process offers a high degree of deoxygenation of renew- able feed streams. Most oxygen species are converted to hydrocarbons and water, CO₂, and CO, which exit the FCC unit on the reactor side and could pose challenges downstream. In pilot plant testing of renewable feed co-processing, the effects of trace oxygenates are often not considered. Nevertheless, these are likely to occur with oxygen-containing feed streams. Trace amounts of oxygenates are commonly found in fossil feed-based FCC product streams like liquefied petroleum gas (LPG) or cracked naphtha. Increasing the com- bined FCC feed oxygen content by the co- processing of renewable feed streams like vegetable oils will increase the number of these oxygenate species. This might neg- atively influence the downstream process- ing of the FCC unit products, while also causing products to exceed specification limits.

ties. To assess the amount of C₃= stem- ming from the renewable feed component, highly sophisticated analytical methods for modern carbon determination might be required.⁷

DID YOU know? The importance of the FCC process in refining, coupled with its high

Data from testing some renewable feed types within Grace showed that the renew- able carbon-containing feed might be pref- erentially converted to C3= compared to fossil feed (FF) components. Figure 2 shows bench-scale pilot plant testing results, which indicate that the C₃= yield in this case increased by about 0.3 wt% FF by blending 9 wt% palm oil with the vac- uum gas oil (VGO). Considering the incre- flexibility, makes it a key candidate for adaptation to new opportunities that are emerging

SR-SCT MAT pilot plant test result

91% VGO + 9% Palm o il

100% VGO

3.8

2.6 3.0 3.8 3.4 4.2 4.6 5.0

3.6

3.4

9% Palm oi l

100% VGO

3.2

2.2

1.5

2.5

3.5

4.5

Cat - to -oi l

3.0

Figure 2 SR-SCT MAT results of C3= yield for 100% fossil-based VGO and a blend with 9 wt% palm oil²