PTQ Q4 2024 Issue

pt q&a

More answers to these questions can be found at www.digitalrefining.com/qanda

Q How can refiners overcome challenges during FCC fast pyrolysis bio-oils (FPBO) co-processing with vacuum gasoil (VGO)? A Guillaume Vincent, Technology Manager, BASF Refinery Catalysts, Guillaume.vincent@basf.com FPBO, most often called bio-oils, have already demonstrated crackability in FCC units but can introduce operational chal- lenges in FCC co-processing applications, such as: • Miscibility issues with fossil feedstocks due to high polar- ity molecules and free water, requiring dedicated storage, pumping, and piping metallurgy. • Instability of bio-oils during transportation and at feed injection temperatures, requiring specific vessels and dedi - cated injection line delivery systems, respectively. If a dedi- cated injection nozzle is required, its location needs to be optimised within the FCC riser. • High variability in alkali, earth alkaline metals, acidity, and oxygen contents. Bio-oils differ from crude oils due to the presence of oxy- gen and elevated levels of alkali metals (such as Na, K), earth alkaline metals (such as Ca, Mg), chlorides, and phosphorus. Since these contaminants can cause catalyst deactivation and operational issues, such as fouling or corrosion issues, it is recommended to reduce their concentration prior to co- processing. At commercial scale, several pretreatment pro- cesses exist to remove contaminants, such as: Particles and other solids in these bio-oils can lead to instability. Filtration has been shown to remove particu- lates such as char and alkali metals. Degumming is another technique that has demonstrated the ability to remove phospholipids and trace metal ions from crude vegetable oils and could be further applied to bio-oils. Water degum- ming is effective for phospholipid removal, while alkali salts require acid degumming. As such, the introduction of alkali and earth alkaline metals should be limited by feed man- agement and careful catalyst selection, such as in-situ cata- lyst technology. In fact, in-situ manufactured catalyst contains the low- est Na content in the FCC industry, which helps mitigate the effect of added alkali metals. Moreover, in-situ manu- factured catalysts exhibit a very high surface porosity that helps mitigate added earth alkaline metals and/or added iron, which typically accumulate at the catalyst edges. In opposition, incorporated catalysts show surface densifica - tion in their fresh state due to the usage of alumina or silica chloride-based binders during the manufacturing process, resulting in a diffusion barrier limiting pore accessibility for further cracking reactions. • Filtration • Desalting • Degumming • Hydrotreating applications • Purification adsorbents.

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100% Gasoil

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Bio-oils might also contain elevated chloride levels, which should be minimised prior to FCC introduction. Chemically, chlorides can result in the reactivation of nickel deposited on equilibrium catalyst, leading to unwanted dehydrogenation reactions (higher hydrogen and delta coke). Operationally, since there is often an excess of NH 3 from feed cracking, any additional chlorides can lead to the formation of incre- mental NH 4 Cl deposits at the overhead of the main frac- tionator. As such, the introduction of chlorides should be limited by feed management and careful catalyst selection to minimise chlorides in FCC catalyst, such as with in-situ catalyst technology. Indeed, in-situ manufactured catalysts do not use chlo- ride-based binders during the in-situ manufacturing pro- cess, as opposed to many incorporated catalysts utilising binders containing chlorides. Feed chlorides can be reduced with purification adsorbents. A chloride guard oriented towards organic chlorides removal is preferred for maxi- mising the dechlorination process. However, preliminary evaluation is highly recommended to assess and confirm its efficiency on a specific bio-oil. Bio-oils also contain significant levels of oxygen-con - taining molecules, resulting in a polar phase immiscible with fossil feedstocks. Additionally, high oxygen levels in feed present challenges in that much of the oxygen can go through reaction pathways to become water, CO, and CO 2 non-value-adding FCC products (an example is shown in Figure 1 using vegetable oil – the increase in non-value products could be even more pronounced for an FPBO). Thus, consideration should be taken for how the use of a bio-oil might impact the FCC yield slate. The mild hydrotreatment of bio-oils could improve mis- cibility through oxygen removal via hydrodeoxygenation. However, the oxygen content at which miscibility is no lon- ger an issue is variable. Catalytic pyrolysis has also been used to stabilise the bio-oil before co-processing through the FCC unit. In catalytic pyrolysis, oxygen is removed as water and carbon oxides over a zeolite-based catalyst. Figure 1 Result of lab-scale cracking tests using FCC catalyst. Originally published in PTQ Q4 2023

PTQ Q4 2024