PTQ Q1 2025 Issue

Hydrotreaters, in general, are not designed to be overly selective to any conversion to jet range material, owing to quench limitations and configuration. Single-stage, once-through hydrocrackers fall into a similar category. Nonetheless, revamp activities can mitigate this problem. However, the carbon chain length of the product must fall within the jet range, C 8-C16, as excessive paraffins can lead to not meeting jet freeze point specifications. Even a kerosene hydrotreater will require modifications, the incorporation of dewaxing catalyst, and adequate quench, at the very least, to be able to feed renewable feeds that produce paraffinic product within the jet boiling range that meet freeze point requirements. At least one technology provider asserts that kerosene hydrotreater co-processing is the preferred cost-effective means to maximise SAF yield.7 Two-stage hydrocrackers have the most potential to both maximise SAF yield concurrent with fossil fuel jet yield and retain the flexibility to adjust renewables content and selec- tivity between diesel and jet. Technology providers have given some guidelines on co-processing routes, as follows:10 • Typically, <5% co-processing:  Requires feed rate adjustment or lower cycle length to manage planned cycle.  No unit revamp; uses hydroprocessing catalyst system with guard catalyst for renewable feed contaminants. • Typically, 5-10% co-processing:  Requires minor compressor modifications and metal- lurgy upgrades in a few locations.  Uses a tailored catalyst system, including significant  Requires new equipment with metallurgy upgrades.  Uses a tailored catalyst system and guard catalysts. Approximate operational impacts of co-processing have also been provided: guard catalyst for implementation. • Typically, 10-20% co-processing: • Some 40-50 Nm3/m3 (18-24 scf/bbl) of hydrogen con- sumption per percentage of renewable co-processed. • Roughly 3°C (5°F) temperature rise per percentage of renewable in feed. • Propane yield about 0.2 wt% fresh feed per 5% renewa- ble feed. HEFA applications The catalysts and catalyst systems used for hydroprocess- ing renewables have been adapted from those currently used in the hydrotreating and hydroconversion of fossil fuel feeds. As a result, they are sulphides of Group 6 (formerly VIB) and Group 9 (formerly VIIIB) elements, such as Mo, W; Ni, and Co, supported on high surface areas, typically alumina, silica-alumina, or alumina-titania, for guard cata- lyst and HDO catalyst uses. There are also zeolites, such as ZSM-5, beta, and USY, for dewaxing and hydrocracking function. Plus, all base metal systems need the addition of sulphiding agents, such as DMDS, for processing pure or near-pure renewable feeds with minimal sulphur content. For designs that comprise two stages (two separate gas recycling components), the second-stage catalyst typically will be a noble metal (Pt or Pd) on a zeolite-containing support. Multi-catalyst graded systems are employed, and

front-end layers of HDO catalyst can be Mo sulphides to mitigate exotherms and rapid hydrogen consumption as well as circumvent premature coking of the catalyst system in addition to providing selectivity to the preferred HDO pathway, limiting CO and CO 2 via decarboxylation. Sulphided NiMo/alumina catalysts have been used as higher activity components in the graded catalyst systems. Their preference is likely driven by a greater resistance to CO poisoning compared to sulphided CoMo/alumina. Dewaxing in a single-stage system can be done using sul- phided Ni, NiMo or NiW on a zeolite-containing support as is done with fossil fuel waxy diesel. In a two-stage system where the second stage is sulphur-free, Pt or Pd on a zeo- lite-containing support is highly effective, as is the case for fossil fuel diesel and jet. The question could be asked whether the sulphided base metal HDO catalysts in current use are the optimum choice for the catalyst system in view of the added cost (and car- bon intensity) for sulphiding agent addition. Sulphided NiMo and NiW catalysts are more active than their unsulphided counterparts. However, carbides, nitrides, and phosphides have been studied and could yield potential. There are sig- nificant driving forces for the continued use of sulphided base metal catalysts: • The activity of the sulphided catalysts is more than ade- quate for the purpose and aligns with existing design con- ditions used in hydroprocessing unit technologies. • Sulphided catalysts are fungible with existing fuels refin- ery hydroprocessing units and are employed in co-process- ing applications. • Economic products are in ready supply owing to a mas - sive manufacturing and support structure in place for the current hydroprocessing catalysts. • The scale of renewables units and their current demand support the existing inertia and provide little incentive for a ‘boutique’ catalyst business based on formulations that have yet to be commercialised. Conclusions Back to the question posed at the outset, ‘Is SAF a poten- tial a refuge and placeholder in the renewables arena?’ At this point, with certain caveats, the answer is only ‘maybe’. There are several sets of dynamics in play: • The European Union sets firm requirements in its direc- tives for SAF (RED III), while the US employs incentives such as IRA tax credits and grants for SAF technology and pro- duction. While the former may remain staunch in setting SAF demand and efforts in the EU, the new US Administration could potentially hinder future loan opportunities and tax credits for SAF producers and refiners. However, projects that have already secured funding commitments will con- tinue as planned. Until recently, the US was previously pro- jected to produce 40% of global SAF supply through 2028. • Global airlines are making far-reaching and highly ambi- tious commitments to SAF usage targets. These targets are only single-digit percentages in near-term demand, but growth in offtake agreements (21.7 billion litres in 2022 agreements; 11.8 billion litres in 2023) puts substance to the commitments. Early producers with suitable economics

PTQ Q1 2025