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Activity still key for FCC catalyst to improve profit margin (TIA)

Nowadays, the gasoline economy still prevails in most markets. The US market has been favouring gasoline yields for a long time.

Tie-Pan Shi
HCpect FCC Catalyst 
(Qingdao Huicheng Environmental Technology)
Article Summary
Even in the Indian refining market where petrochemicals have been strongly focused, gasoil or resid feed still needs to be cracked to gasoline before they are further converted to LPG. The FCC reaction system is highly complicated but, to simplify, the ability to crack diesel range molecules to a gasoline fraction is defined as the conventional cracking activity, best facilitated by Y-zeolite. The cracking of the bottoms fraction into diesel range molecules mostly occurs on the matrix.

HCpect (Qingdao Huicheng Environmental Technology) has been focusing on improving both matrix and Y-zeolite activity to create value for refining customers, all while maintaining or improving coke selectivity. The Y synthesis and treatment has been optimised to offer improved activity, while the treatment of non-framework aluminum improves coke selectivity. On matrix technology, HCpect has a combinatorial system using compensating natural clays to form desirable pore size structure. Moreover, the clay and specialty alumina complement each other for optimised pore size distribution. Both technologies were deployed in a commercial trial in a Sinopec refinery. For a fair comparison, both the current and the incumbent catalyst were without metal trapping technology, despite notable levels of metals on the Ecat.

The FCC unit throughput is 28 000 b/d with a dual reaction zone design. The secondary reaction zone promotes hydride transfer and isomerisation reaction to reduce olefin content in the gasoline product. The catalyst inventory was 380-400 t and the catalyst addition rate was 3.0 t/d. During the otherwise smooth trials without major operating disruptions or cut point shifts, the feed API was consistent at 21.2±0.6°. The combined Ni+V content on the Ecat was approximately 4000 ppmw, with an uptick toward the end of the second trial.

The conversion showed a 1.8 wt% increase when significant inventory was replaced with HCpect catalyst (while far from an ideal catalyst inventory replacement, here comparison was done at ≥20% vs ≤20% inventory replacement levels), as shown in Figure 1. During the trial, small amounts of ZSM-5 additives were used throughout the trial. To eliminate the artefacts of the inconsistent addition of ZSM-5, the combined weight yield of LPG and gasoline is shown in Figure 2; an average increase of 1.7 wt% was evident. Also shown in Figure 3 is the slurry yield comparison against conversion. The new matrix showed improved slurry yield and selectivity when compared against the catalyst with traditional matrix and the incumbent catalyst.

Overall, the value creation through activity and bottoms cracking improvement still proved pivotal to the bottom line of the FCC optimisation. In this trial, the profit margin was improved by $1.13/bbl at the current inventory replacement level. This margin can be further improved when the catalyst replacement reaches an ideal 70-80% level, primarily due to the improved activity through bottoms cracking and Y-zeolite cracking.

This short case study originally appeared in PTQ's Technology In Action feature - Q4 2018 issue.

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