Catalysis 2025 Issue

Value of pre-activated catalyst in HEFA units

Hydroprocessing units designed for fossil feedstocks cannot easily switch to HEFA feedstock processing without a solution that addresses the significant challenges

Steve Mayo Eurecat

T he rapid increase in processing capacity for hydro- treated esters and fatty acids (HEFA) to produce renewable diesel (RD) and sustainable aviation fuel (SAF) has been nothing short of phenomenal. Starting from less than 50 KBPD capacity 10 years ago, global capacity is now approaching 500 KBPD. Despite recent setbacks in unit profitability, strong growth in HEFA processing capac - ity is expected to continue through 2030, with a projected doubling of current capacity. To date, North America has seen the largest increase in HEFA processing capacity, driven by strong incentives and subsidies for RD. By 2030, HEFA processing capacity is projected to shift from RD in favour of SAF, with all regions expected to show substantial capacity gains compared to the present level (see Figure 1 ). While similar in some respects to the hydroprocessing of fossil feedstocks in which refiners are well versed, hydro - treating HEFA introduces significant challenges: • The feedstock is sulphur-free. • High olefin and oxygen content make the feedstock very reactive. • Very high hydrogen consumption. • Large reaction exotherms. • Copious quantities of reaction byproducts (C₃H₈, H₂O, CO, CO₂). • Phospholipids may cause catalyst activity loss and pres- sure drop build-up. • Feedstock corrosivity may increase. • Long-chain n-paraffins require catalytic dewaxing and/ or hydrocracking to meet cloud point (RD) or freeze point (SAF) specifications. • Undesired conversion to lighter products (gas, naphtha) significantly reduces unit profitability. Grassroot units licensed from technology providers address all these challenges with bespoke process design and catalysts. Hydroprocessing units designed for fossil feedstocks are usually incapable of directly switching from fossil to HEFA feedstock processing. Even small amounts of a renewable feedstock (<10%) processed together with fossil feedstock in an existing unit will see compromised operation and cycle length. However, those same units can often be revamped to process 100% renewable feedstocks. Technology provid- ers can reuse much of an existing unit’s hardware along

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with a new catalyst system to switch the unit from fossil to HEFA service. This is particularly true of hydrocracking units, which already have the robust hardware needed to accommodate the HEFA feedstock’s high reactivity and hydrogen consumption as well as improve the resulting cold flow properties. Figure 2 shows the five general reactions that take place in a HEFA unit:  Phosphate removal from phospholipids. v Saturation of olefins in fatty acids. w Propane removal from the glycerol backbone of the triglyceride. x Deoxygenation of free fatty acids. y Cracking and/or isomerisation of normal paraffins. Reaction one depends on the feedstock origin as well as pretreatment steps completed ahead of the HEFA unit. Reactions two to four are common among most HEFA units and are often referred to as hydrodeoxygenation (HDO) or hydrotreated vegetable oil (HVO) reactions. The objectives of Reaction five depend upon the desired product split between RD and SAF. Ex-situ catalyst activation The sulphur-free HEFA feedstock initially seems like a pos- itive aspect of HEFA processing compared to processing fossil feeds. No sulphur and no hydrogen sulphide (H₂S) Figure 1 Current and projected HEFA processing capacity to RD and SAF Sources: EIA/USDOE, IEA, S&P Global, Argus

Catalysis 2025