Decarbonisation Technology May 2025 Issue

To meet these complex requirements, Topsoe has developed specialised catalysts for these purposes, enabling the production of on-spec renewable diesel and SAF without operational issues. Catalyst innovations for renewable fuels Central to this has been the introduction of a range of dedicated catalysts designed specifically for the hydroprocessing of renewable feedstocks. Recently launched to the market are third-generation Topsoe HDO catalysts selective for the hydrogenation route designated TK-3001, TK-3002, and TK-3003. These will provide producers with better HDO selectivity via the hydrogenation route, higher activity, and high metals, resulting in a significantly longer cycle length. The higher HDO selectivity throughout the cycle length of the catalyst will result in a significantly higher average product yield compared to the previous generation of HDO catalysts, which will increase the profitability of the plant. The catalyst loading also includes an isomerising dewaxing catalyst to ensure that the renewable diesel and SAF meet the required cloud point and freeze point of the final product. The specialised guard beds catalysts are designed to pick up the contaminants in the feedstock, such as P, Na, K, Ca, Mg, Fe, Ni, and V. The most significant poison is typically phosphorus (P). To address this, Topsoe has developed a more efficient P guard, TK-3000 PhosTrap (see Figure 1 ), which picks up four to six times as much P on a volume basis as its previous P guard in renewable service (see Figure 2 ). Reduced complexity and lower costs In addition to picking up contaminants, the guard bed catalysts are designed to use the hydrogenation route like the main bed catalyst to ensure that the oxygen in the triglyceride is converted to water instead of CO2 . The hydrogenation route improves the product yield and will not make CO2 as opposed to the decarboxylation route, which produced significant amounts of CO2 . The fact that Topsoe’s specialised HDO main bed catalysts and guard bed catalysts

Figure 1 TK-3000 PhosTrap catalyst for improved phosphorus control

these complexities, the consequences can be severe: poor product yield, byproduct formation, accelerated catalyst deactivation, and pressure drop build-up. Additionally, the hydrotreated product has to meet the required product specifications, namely ASTM D-975 for diesel and D-7566 for SAF, including the cold flow properties, which are critical for fuel performance in colder climates (diesel) or at altitude sustainable aviation fuel (SAF). To address these challenges, catalyst systems must be tailor-made for renewable feedstock processing. This involves developing catalysts that can effectively manage the hydrodeoxygenation (HDO) of renewable feeds, improve cold flow properties through isomerisation, and maintain stable operation under varying conditions.

Reference

TK-3000 PhosTrap

Figure 2 Phosphorous pick-up of TK-3000 compared to previous-generation P-trap