Question
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What is the latest progress in FCC catalysis to boost bottoms upgrading?
Mar-2022
Answers
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Tom Ventham, G. W. Aru, LLC and Unicat Catalyst Technologies, tom.ventham@gwaru.com
Refiners with FCC units consistently aim to maximise margins at high crude oil prices, and this has led to a renewed interest in bottoms upgrading. The catalytic technology to achieve this improvement is, however, basic and traditional. Bottoms upgrading additives are simple, high-matrix additives that crack long-chain paraffinic intermediates, that would otherwise become part of the slurry product yield, to boost yields of move valuable products. UMCB is much like other additives marketed for bottoms upgrading and also contains components to reduce the effects of dilution when UMCB is used in high proportions in the FCC unit. It is being tested by major refining companies and is supported by the best-in-class technical team of FCC additives experts at G. W. Aru, LLC & Unicat. It is this ability to support a refiner around the use of this dynamically functioning FCC additive that is typically the differentiator to gaining the full improvements possible when deploying a bottoms upgrading strategy of this type. We encourage all refiners interested in this type of operation to explore all of these opportunities open to them.
Firstly, we must address how some refiners are looking to implement bottom upgrading additives to enhance margins. One benefit of improved margins is the ability to invest OPEX to further stretch profitability of the FCC. Some refiners have begun using, or increased their use of, ZSM-5 type additives (such as Ultra C3Booster or Ultra C4Booster from G. W. Aru, LLC & Unicat) to boost yields of valuable LPG olefins or economic drivers to enhance octane value of gasoline. Physical limitations moderating ZSM-5 use include wet gas compressor or gas plant hydraulic constraints. An economic pivot-point exists that can be modelled in LP software, steady-state simulation models, or simple yield calculations, which recommends a reduction in riser outlet temperature to decrease volume load to the gas concentration system to increase ZSM-5 use to produce a higher proportion of the most valuable molecules (propylene and butylene) more efficiently, and therefore more profitably, to fill that vacated space.
Downsides of a severity reduction include two areas of concern. The first most obvious is that main fractionator bottoms (also known as, slurry, DCO, CLO) yield will increase with a decrease in severity. The additive approach discussed in this question is the use of dynamic and flexible additions of bottoms upgrading additives (such as Ultra MCBuster “UMCB” from G. W. Aru, LLC & Unicat) to breakup supplementary bottoms production into more valuable products to maintain optimal product yields. The second concern that can be encountered is a reduction in riser-side severity leads to mirrored fall in regenerator temperature (at constant delta coke). At lower regenerator temperatures, kinetics of CO oxidation will be impacted and further promotion activity, in the form of a platinum or palladium containing CO promoter, will be needed to maintain control of unit afterburn as defined by the delta between dilute phase temperature and dense bed temperature. In FCC units limited by NOx emissions it may not be possible to increase use of CO promoter (particularly if the unit is operating at high rates meaning CO promoter additions are already forced higher). Furthermore, current high metal costs of platinum and palladium mean there is also a cost implication to any increase in CO promoter use.
For refiners in this difficult situation, or indeed any refiners interested in unit optimisation, the patented (US Patent number 11,224,864) Great FCC Promoter (“GFP”) range of CO promoters from G. W. Aru, LLC & Unicat gives the option to switch to a lower precious metal content CO promoter that is proven to operate equally or more effectively compared to conventional CO promoters with much higher precious metals content. As a result of this lower precious metal loading, GFP is both lower cost and produces less NOx to give a more efficient and cost-effective afterburn control within NOx constraints when targeting operational modes such as this.
Mar-2022
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