Catalysis 2024 Issue

Bio-oils Although the bulk of available plant-derived oils for fuel applications are directed towards hydroprocessing (renew- able diesel and SAF), there are several FCC units frequently processing FOGs. One driver for the increase in FCC co-processing trials is the flexibility of the FCC to handle feeds with increased contamination, such as tallow and UCO, which may be challenging for hydroprocessing. Bio-oils, as the other biogenic feed option, have distinct advantages over FOGs because they do not compete with food resources. They utilise lower-valued waste streams from the agricultural (corn stover, bagasse) and forestry (forest residues, sawmill wastes) industries, biogenic frac- tions of municipal wastes (paper/cardboard, food waste), non-food crops (such as switchgrass), and animal/livestock manure and sewage. Over the last 30 years, a diversity of conversion technol- ogies, including the thermochemical conversion of these waste streams through fast pyrolysis (FPBO), slow pyrol- ysis, catalytic pyrolysis (CPO), hydrothermal liquefaction (HTL), hydro-pyrolysis, and gasification technologies, have been developed at various universities, national laborato- ries, private companies, and start-ups. FPBO has reached commercial scale. HTL technology demonstrations and commercial plants are coming online and are expected to increase over the next several years, particularly for wet biomass feedstocks such as sewage sludge. 3 Variability in bio-oil properties The biomass feed and conversion technologies result in signif- icant variability in bio-oil properties, including acidity, stability, solubility, oxygen, and free water content, influencing oper - ational and catalytic challenges in FCC co-processing. Poor thermal stability of bio-oils leads to an increased propensity for the formation of carbon deposits. High oxygen content and elevated concarbon residue (CCR) levels can lead to changes in heating value and increased delta coke in the FCC unit. The increased delta coke of bio-oils may be a concern in units with maximum regen temperature and main air blower

limits. Because of the challenges associated with bio-oils, some refiners have considered alternative insertion points, such as coking units or as a fuel for utilities. However, with proper consideration for feed injection, FCC co-processing has been demonstrated commercially, with a few short- term commercial trials introducing small amounts of bio-oil (<<2 wt%). Confidence to conduct their commercial trials stems from some of the pioneering work by Petrobras over the last few decades, demonstrating FCC co-processing of various bio-oils from laboratory through pilot and demonstration scales. 4,5 Petrobras recently announced a commercial-scale trial scheduled for June 2024 for FCC co-processing Bio-oils, as the other biogenic feed option, have distinct advantages over FOGs because they do not compete with food resources of bio-oil after successfully processing 100% SBO in its Riograndense refinery in 2023 with the proprietary ReNewFCC catalyst technology produced at FCC SA (a joint venture between Ketjen and Petrobras). 6 Operational challenges 3,7 FCC co-processing will create unique process challenges for the various feed options. These challenges may vary depending on refinery equipment, logistics, process con - ditions, and the type of oil planned for co-processing. Most oils considered for processing have a short shelf life relative to conventional hydrocarbon feeds. With time and temperature, these oils are likely to undergo oxidation and other reactions during storage or feed injection. Above 100°F (38°C), oil decomposition will increase. Above 300°F (150°C), carbonisation may occur. In general, lower

Metal and other contaminants found in various FCC feedstock options and impacts on catalytic performance Concern Parameter VGO FOG WPO Bio-oils base feed refined/crude liquefaction oils from agricultural & forestry vegetable oils/UCO waste plastics liquefaction oils Dehydrogenation V, Ni, Cu, other, wppm <50 <10 <660 <50 Zeolite poison Na & K, wppm <20(Na) <300 <10 <200 Eutectic Ca, Mg, Fe, wppm <0.1-20 <200 <750 <600 and pore Si, wppm Trace <25 <7,500 <50 plugging P, wppm Trace <250 <200 <50 CI, wppm Trace <50 <2,700 <60 Corrosion and Br & F, wppm – N/A <6,800 N/A potential TAN, mgKOH/g <0.25 <1.4 <0.25 <128 poisons N, wt% <1 <0.1 <2 <1.4 wt% O <1 8-12 <2.5 15-54 Other wt% H 2 O <0.5 <0.5 <0.5 5-25 S, wt% <2.3 <0.2 <1.2 <0.3 CCR <3 <0.5 <4.5 <20

Table 1

Catalysis 2024