Catalysis 2026 Issue

residue (VR), deasphalted oil (DAO), and heavy coker gas- oil (HCGO) contain very high amounts of asphaltene-like carbon molecules, which are measured and reported as Conradson Carbon Residue (CCR) or Micro Carbon Residue (MCR). FCC heat balance is sensitive to changes in CCR since most CCR forms coke, also known as ‘feed coke’. It can lead to an increase in delta coke and higher regenerator temperatures. The impact of feed coke can be partially addressed by minimising the feed preheat temperature. Heavy feeds can also increase occluded coke, which can be

D ry gas

Dehydrogenation promoted by Ni (produces aromatics and H)

Elemental map of Ni on E - cat

Side chain cracking

Aromatics condensation leading to c oke and more H

C oke

Figure 2 Hydrogen and coke-making reactions promoted by nickel

• Sulphur. • Nitrogen. • Residual carbon (CCR).

minimised by optimising the stripping steam. Additionally, refiners may consider using coke-selective catalyst, which can reduce catalytic coke. When high CCR feed is to be processed for the long term and previously described ‘soft’ handles are insufficient, hardware solutions may be needed. The use of advanced feed nozzles can help create more dispersed feed atomisa- tion and minimise coke formation from non-vaporised feed. Coke formation due to post-riser thermal cracking can be minimised by an advanced riser termination device. Coke, due to inefficient stripping, can be minimised by improved stripper design and higher efficiency. When the regenera - tor’s dense bed temperature exceeds operational limits, a catalyst cooler may be considered for removing the excess heat from the regenerator.1 When some shale oils, light crudes, or pyoils derived from polypropylene or polyethylene-based plastics are co-processed in an FCC unit, it can reduce the CCR of the combined feed, which can cause a drop in regenerator tem- peratures, and the unit can face the constraint of high cata- lyst circulation. In such cases, maximising the feed preheat temperature can help, but if the unit is not equipped with a feed preheat furnace, this option may provide only limited relief. In such a scenario, refiners may consider adjusting the coke selectivity of the FCC catalyst to increase the delta coke and maintain regenerator temperature. Lower regen- erator temperatures impact combustion kinetics and cause afterburn. Use of CO promoter additive helps in reducing the afterburn and maintaining regenerator temperature. Contaminant effects Extreme feeds can cause sudden, significant increases in contaminants such as sulphur, nitrogen, metals, and chlo- rides in the combined feed to the FCC unit. Increases in feed sulphur can affect product quality, impacting downstream product treating units. Hence, checking the sulphur removal capacity of the treating unit is important before starting to process high-sulphur feeds. If an upstream pretreater for FCC feed (for example, an FCC feed hydrotreater) is

• Full metals assay, including especially nickel (Ni), vanadium (V), sodium (Na), iron (Fe), copper (Cu), calcium (Ca), and potassium (K).

• Chlorides. • Distillation. • UOP characterisation factor (KUOP).

Other important information, such as aromatic content, molecular weight, and hydrogen content, can either be measured or calculated based on these bespoke properties. Extreme feeds processing challenges Depending on the properties of extreme feeds and their impact on the combined feed to the FCC unit, many chal- lenges are observed, primarily divided into three groups: u Heat balance effects. v Contaminant effects. w Product yield and quality effects. Heat balance effects Extreme feeds such as atmospheric residue (AR), vacuum

Plant data of BoroCat catalyst processing a high Ni feed

Parameter

Previous catalyst 0.9049

Borocat

Relative

delta

Feed SG

0.9063

+0.2% -1.9% +1.7%

Feed CCR, wt% Feed Ni, ppm-wt Ecat Ni, ppm-wt Dry gas, wt%

5.3

5.2

17.5

17.8

10,300

5.5 8.3

4.7 8.3

-14.5%

LPG, wt%

Gasoline, wt%

44.4 29.9

44.8 30.6

+0.9% +2.3%

LCO, wt%

Bottoms, wt%

4.4 7.6 3.7

4.4 7.2 3.5

Coke, wt%

-5.3% -5.4%

H₂/CH₄ mol ratio

Table 1

Catalysis 2026