(583k) Catalyst-Feed Interactions in Fluid Catalytic Cracking Systems: Understanding the Feed Properties Effect

Catalyst-feed interactions in Fluid Catalytic Cracking systems:

Understanding the feed properties effect.

Dariusz Orlicki[1], Uriel Navarro, and Michelle Ni

W.R. Grace & Co., Grace Catalysts Technologies

Columbia, MD USA

Advanced Catalyst Evaluation (ACE[2]) apparatus has become an industry-dominant, high-throughput bench-top technique for catalyst evaluation and ranking.  Since feed quality is considered the most influential single factor affecting the FCC unit performance, special attention is always given to the selection of the appropriate feed that closely resembles one from field operations. Both the ACE testing experimental conditions and the laboratory deactivation techniques of fresh catalysts put some limits on the ability to laboratory-simulate FCC unit field performance. There are, however, well-established methods, based on chemistry of cracking reactions, physical laws of transport phenomena, and heuristic observations that help to bridge the gap between a laboratory experiment and a field operation.  

In this work, we have assembled a collection of over 100 feeds originated from different geographical locations and subject to special initial processing. Extra attention was paid to make sure that this collection represented the type of feeds that are used by industry today, including North American shale oil. All feeds were thoroughly characterized for physical and chemical properties using standard industry methods. The measured properties were density, boiling point temperature distribution by SIMDIS, Refractive Index, Conradson Carbon, total and basic Nitrogen, Sulfur, and metals such as Nickel and Vanadium content. While total hydrogen content was measured by combustion using LECO[3]CHN628, the quantitative assessment of hydrocarbons types was done by H-NMR. Some feed samples were also evaluated by SARA, UV-vis, and Mass Spectroscopy.  At the end, all those feeds were evaluated in the ACE apparatus using three commercial catalysts provided by Grace. These catalysts were laboratory-deactivated using the CPS metal-free deactivation protocol. The rationale for using metal-free deactivation, besides simplifying the analyses, was to focus on catalyst-feed interactions during the cracking process.

For data analyses, we have used a lump model that was originally developed in collaboration between both Professor George Bollas and Dr. Monica Navarro from University of Connecticut and the R&D group from W.R. Grace & Co. The kinetic constants from the model were correlated with feed properties that provided not only an accurate predictive tool for understanding of catalyst-feed interactions but also insight into engineering of cracking processes and scale-up methodology.