PTQ Q4 2025 Issue

Maximise utilisation of high-activity hydrotreating catalysts

Good practices to maximise product profit, extend run length, and improve reliability

Andrew Layton KBC (A Yokogawa Company)

I magine feeding the wrong crude blend into a refinery. The moment it hits the crude unit, there is no going back. Every downstream, unit will feel the consequences of the reduced capacity, unexpected constraints, efficiency loss, reliability incidents, and difficulty meeting product quality for the rest of the run. The right catalyst defines what a unit can produce, and its utilisation decides how much of that promise is deliv- ered. Today’s refiners operate in a tighter window than ever: stricter product specs, more variable feeds, and longer run lengths between turnarounds. At the same time, heavier crudes and higher cracked stock content raise temperature requirements and accelerate catalyst deactivation. In some commercial units, the temperature increase requirement (TIR) has exceeded 1°C per month, a rate that can shorten cycles by several months. Getting the most out of a high-activity hydrotreating cat - alyst is not about a single improvement. It takes discipline in several areas across the entire lifecycle. From the moment the catalyst is selected, every choice in handling, reactor design, loading, operation, optimisation, and monitoring influences whether that catalyst delivers its full potential or else falls short. Several of the key areas to consider are summarised in the following discussions. Each topic has many associated good practices, which are beyond the scope of this article. Catalyst selection The first crucial step for the given refinery operation is catalyst selection. With many similar products available, a structured approach ensures the choice is based on both technical and economic factors. Several vendors should always be considered to find the best catalyst for the job and keep catalyst costs down by promoting competition, rather than getting locked into long-term contracts. Key cri - teria include: • Relatively new catalyst performance compared to a well- known standard catalyst. • Operating experience band and stability. • Price and availability. • Backup plans if performance falls short. • Start-up and follow-up support. • Hydrogen consumption. • Start-of-run (SOR) and end-of-run (EOR) operating conditions.

• Yields and product properties. • Any special handling or start-up procedures. • Impact of a range of feeds (no single feed case). • Exotherm potential on loss of recycled gas (impacts emer - gency procedures). • Supplying existing vendor operational data for the prepa - ration of a realistic proposal. Performance guarantees should include correction fac- tors. Even the same catalysts in similar units can behave differently because of variations in feed, reliability, and oper - ations. Like crude blending, the choice must fit the specific unit, not just the market average. Choosing the right catalyst is much like tailoring a suit. The best material will only per - form at its best if it is cut to fit the exact shape and require - ments of the wearer. In the same way, a catalyst must be matched to the unique operating profile of its unit. It is then good to have a criteria checklist to compare the differences in the proposal. Catalyst handling and storage Once chosen, the catalyst must be protected until it is in the reactor. Obtaining samples ahead of time is important, as is checking labels on arrival. It is useful to perform rough strength tests for the associated larger inerts (non-catalytic bed materials used for support and flow distribution). Weak inerts can break down on loading, migrating, and increasing pressure drop. Catalysts should be stored in rainproof and sunproof con - ditions upon receipt. Some catalysts are pre-doped with various hydrocarbons or sulphur compounds, which can decompose if heated but make start-up easier. Always check immediately that the correct catalyst has been shipped and that inerts meet strength requirements. Protection up front prevents costly mistakes down the line. Loading and unloading under nitrogen was common from the 1970s through the early 2000s. After several incidents in the mid-2000s, perhaps as operating experience less - ened, some companies and regulators felt compelled to limit or prohibit reactor inert entry. While nitrogen-related incidents are rare, they are serious. Procedures have been further tightened to minimise incidents. Without nitrogen handling, reusable catalyst is often wet dumped, which increases catalyst cost, complicates reuse, and creates a wastewater production issue.

PTQ Q4 2025