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Jun-2015

Managing uncertainties and 
increasing profits (TIA)

In response to the rare-earth supply crisis in 2010, and the tight oil revolution in the United States, Grace commercialised eight new low- or no-rare earth FCC catalysts and additives.

Christophe Chau and Rosann Schiller
Grace Catalysts Technologies

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Article Summary
The first in the series, Achieve 400 FCC catalyst, addresses the octane debits that were being encountered by North American refiners. The technology has delivered an economic uplift on the order of $3-7M/yr in multiple commercial applications due to the boost in slurry conversion, FCC naphtha octane, and butylene yield.

Five key functionalities were developed in the development of the new catalyst series, to provide yield flexibility for refiners:
•    Increase distillate yields with high diffusivity matrices
•    Reduce dry gas with advanced metals traps
•    Drive conversion with ultra-high activity zeolites
•    Maximise resid processing with leading coke selectivity
•    Boost refinery octane with dual-zeolite technology.

The following examples illustrate how Achieve catalysts have been applied commercially to improve FCC unit yield and profitability.

Maximising conversion
When processing lighter feedstocks, insufficient catalytic activity requires that the catalyst circulation rate increases so that conversion, and thus the coke yield from the catalyst, increases to satisfy the FCC heat balance. If the FCC unit cannot physically circulate enough catalyst, it will be necessary to either reduce the unit charge rate or the reaction severity to stay within the catalyst circulation limit. Use of a high activity catalyst can counter the effects of low delta coke, but it is important to select a catalyst with the proper coke selectivity (coke to conversion relationship). Achieve 100 catalysts are formulated with ultra-high activity zeolite to counter the effects of low delta coke, while delivering the proper coke. In commercial application, Achieve 100 delivered enhanced activity over a competitive catalyst. At constant coke, the switch to Achieve 100 resulted in higher activity, higher gasoline and lower bottoms and an economic uplift of ~$0.40/bbl.

Maximising fuels yields
Grace has been successful at incorporating both nickel and vanadium metals trapping into FCC catalyst, mitigating the negative impacts of the metals. An example of metals trapping performance is evident in Achieve 200 catalyst. Refinery operating data after reformulation to Achieve 200 catalyst resulted in higher gasoline yields and lower hydrogen, delta coke and slurry yield. The superior metals tolerance of the catalyst allowed the refiner to increase conversion without increasing catalyst addition rate. The increase in gasoline yield and drop in slurry resulted in a benefit of ~$0.70/bbl for the refinery.

Maximising refinery octane
A common challenge reported by refiners operating on unconventional feeds, such as shale or tight oil, is a loss of gasoline pool octane, caused by reduced volume of alkylation feedstock. Achieve 400 catalyst is formulated with multiple zeolites with tailored acidity, to deliver an optimum level of butylenes to keep the alkylation unit full and maintain refinery pool octane. Incorporation of isomerisation activity into the catalyst particle itself results in a more desirable yield pattern than would be realised by use of a traditional octane boosting FCC additive. In addition, Achieve 400 has been shown to increase the octane of FCC naphtha. In multiple commercial trials, the catalyst is delivering incremental octane and butylene, worth on average $0.6/bbl.

Managing unconventional metals
A resid unit experienced deteriorating performance as a result of processing high carbon, high iron opportunity feedstock and experienced iron poisoning. The symptoms of iron poisoning include a loss of bottoms cracking, as feed particles are blocked from entering the catalyst particle, and a drop in conversion. Catalyst design can be optimised to resist the effects of contaminant iron (and calcium) found in many opportunity feedstocks. The high diffusivity matrices in Achieve possess an optimum distribution of mesoporosity, maintaining performance because diffusion to active sites remains unhindered, even at high-contaminant metals loadings. Commercial data demonstrate an improvement in gasoline and distillate yield, and a reduction in both dry gas and bottoms yields due to improved coke selectivity. Using base case economics, the shift to Achieve resulted in an annualised yield improvement of $10M over the base catalyst formulation.

As refiners adjust their operating conditions and yield objectives, Grace’s newest FCC catalytic solutions will help them maximise profit and manage the uncertainties of increased opportunity crude processing.

This short case study originally appeared in PTQ's Technology In Action feature - Q3 2015 issue.
For more information: greg.teneyck@grace.com
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