The quiet fight to keep reforming catalysts alive

In catalytic reforming—where paraffins become high‑octane aromatics—deactivation is a game of microns and minutes. Platinum (Pt)‑based catalysts are exquisitely sensitive to sulfur and nitrogen; even trace levels poison active sites, drive up coke, and crush hydrogen yield. The industry answer is a three‑part playbook: ultra‑deep feed cleanup, precise regeneration, and smarter catalyst chemistry.

Consider the numbers. Many plants hydrotreat naphtha (“NHT”) down to less than 0.5 ppm (wt) sulfur and less than 0.5 ppm (wt) nitrogen (ppm = parts per million by weight), because “even trace S or organic N irreversibly poison active sites” (ResearchGate; ResearchGate). And with Indonesia tightening gasoline sulfur from about 500 ppm to about 50 ppm under planned “Euro IV” standards, upstream naphtha will need ultra‑deep hydrotreating (TransportPolicy; The Jakarta Post).

Feed pretreatment to ppb levels

Modern NHT operation not only removes heteroatoms; it also saturates olefins to less than 0.5–1 wt% (wt% = weight percent) and drives sulfur and nitrogen down to ppb (ppb = parts per billion) to protect precious metals (ResearchGate). The reason is stark economics: for a 25,000 BPD (barrels per day) CCR (continuous catalyst regeneration) reformer, just 0.5 ppm of organic nitrogen in the feed can deposit approximately 2 tonnes per year of ammonium chloride (NH₄Cl) downstream, fouling exchangers and tying up carryover chloride (ResearchGate).

Sulfur—often as hydrogen sulfide, H₂S—binds platinum as inactive PtS, dropping hydrogen yield and overall activity (ResearchGate). Pushing feed sulfur and nitrogen to ≪0.1 ppm (by multi‑stage hydrotreating or adsorbents—adsorbents: materials that trap impurities on surfaces) extends reformer cycle life by months or years; one refinery processing dirty coker naphtha roughly tripled its NHT cycle from about 9 to 27 months after improved treatment (DigitalRefining). Catalyst textbooks and handbooks (Springer/IFP)* echo the typical feed specification of ≤0.5 ppm S/N and quantify poison effects with the same orders of magnitude (ResearchGate; ResearchGate).

CCR regenerator design and modes

Coke formation is inevitable in reforming. CCR units therefore continuously circulate catalyst through a regenerator that burns off carbon. A well‑designed unit can combust on the order of 5 wt% coke per pass at full catalyst flow—operators size oxygen/air flows and residence time around this design point (AFPM). In practice, many UOP Platforming CCR regenerators will tolerate higher coke loads if flow zones are clean and uniform (AFPM).

Operations balance reactor coking rate against regenerator burn rate. If coke exceeds design, many sites shift to “black‑burn” mode—reduced catalyst circulation with excess air—to remove coke more aggressively (AFPM). Black burns maximize coke removal (diffusion is less limiting) but must be time‑limited to avoid sintering; prolonged black burn can cause Pt/Re agglomeration and activity loss, making “white‑burn” phases (lower duty) necessary to restore metal dispersion (AFPM).

Hardware matters, too. Regenerators rely on distribution grids and lift/riser sections to keep catalyst residence uniform at about 650–700°C for efficient combustion. Design also makes room for chloride (Cl) re‑insertion: once coke is burned, catalysts are re‑chlorinated to maintain surface acidity, and THT or NH₄Cl by‑products are managed in cooler zones. Re‑chlorination is a chemical injection step (accurate chemical dosing: dosing pump). The through‑line: CCR regenerator systems are engineered to balance continuous coke burn with minimal thermal damage, using black/white burn modes to handle excess coke while preserving metal dispersion (AFPM; AFPM).

Stabilized supports and multi‑metal catalysts

On the materials side, catalyst makers are extending life by stabilizing supports and tuning metals. Axens reports that advanced alumina supports minimize specific surface area loss over hundreds of regenerations, which preserves acid sites; when area collapses, units need higher chloride injection (and see higher losses) and risk platinum sintering (Axens blog). New formulations use optimized calcination and dopants to lock crystallite structure and maintain pore volume (Axens blog).

Metals are engineered as well. Bimetallic Pt–Sn and Pt–Re catalysts broaden the balance of dehydrogenation vs hydrogenation and improve coking resistance. Axens’ Symphony family includes Pt–Sn and Pt–Re on dense gamma‑Al₂O₃ aimed at high octane and aromatics output (Axens). In practice, these innovations enable much lower‑pressure operation: moving from 20 barg semi‑regen reforming to modern low‑pressure CCR with advanced catalyst increased reformate yield by about 10 wt% and hydrogen output by about 50% in one study (ResearchGate).

The latest formulations also feature engineered pore architectures (meso/macropores) to accommodate coke and trace poisons. The net effect: longer run lengths via stabilized supports that limit area loss and metal sintering (Axens blog), multi‑promoter metals (Pt–Sn, Pt–Re) that maintain activity in the presence of traces, and pores that blunt deactivation. Producers report that such catalysts routinely achieve cycle lives of 18–24+ months (versus about 12–18 months for earlier catalysts) under high‑severity feeds, with dozens of commercial CCR units—40+ references in 8 years—using these advanced families (Axens).

What the references say

Industry reviews, technical reports and standards converge on the same themes. Catalyst textbooks and handbooks (Springer/IFP)* cite ≤0.5 ppm sulfur/nitrogen in feed and document poison impacts—such as approximately 2 tonnes per year of NH₄Cl from a 25,000 BPD CCR reformer at 0.5 ppm organic nitrogen (ResearchGate; ResearchGate; ResearchGate). Trade publications and vendor data detail CCR operation—5 wt% design coke burn, black/white burn practices, and regenerator balancing (AFPM; AFPM)—and regulators in Indonesia signal the macro drivers by tightening fuel sulfur limits from about 500 ppm toward about 50 ppm (TransportPolicy; The Jakarta Post).