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(2016) Question 7: How is propane content in the refrigeration loop optimized against the compressor capacity to minimize contractor temperature? Do you have a good process model to predict the optimum propane content?

There is an optimum propane concentration in the refrigerant that will allow the alkylation unit to operate at a maximum alkylate throughput when the unit is up against limitations of both the compressor and the reaction zone heat removal capability. That optimum concentration of propane will vary from unit to unit and can be different seasonally. It can also be different from night to day or if exchangers are fouled, etc.
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(2010) Question 85: What is the typical range that you employ for iron content on FCC equilibrium catalyst? What methods are available to determine how iron is accumulated on the catalyst surface? How does the distribution of iron on the catalyst surface impact the FCC operation, yield structure and emissions?

There are several methods available to quantify iron contamination on catalyst. Scanning Electron Microscopy (SEM) pictures are a valuable means to qualitatively assess iron laydown morphology on the catalyst particle.
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(2010) Question 86: In your experience, what are catalyst best practices to shift FCC yields rapidly between gasoline and diesel maximization and then back again? Many catalyst suppliers are recommending blended catalyst systems. Do you believe this catalyst/additive blending is the best approach?

Co-catalysts are a new product category providing the refiner with the flexibility to change the product slate of the FCC without changing the FCC catalyst. Changing between a maximum gasoline co-catalyst and a maximum LCO co-catalyst will allow the refiner to rapidly capture the most favorable economics at all times – maximizing FCC profitability. Co-catalysts are added to the base catalyst to rapidly change the core performance of the FCC.
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(2010) Question 87: In your experience, how does catalyst activity affect the catalyst's coke selectivity and the FCCU's delta coke? How are the coke selectivity and delta coke related? Lastly, discuss how to determine the proper activity to maximize conversion.

When designing an FCC catalyst, one must consider coke selectivity, delta coke and total coke yield. Coke selectivity is the relative coke-making tendency of the catalyst, or in other words, a catalyst with good coke selectivity produces higher conversion per unit of coke make than the reference catalyst.
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