The diffusion rates
of feedstocks and intermediate products in
fluid catalytic cracking (FCC) catalysts have relevance for the product
selectivities obtained from the conversion of feedstocks in the FCC
process. A simple and robust method was developed to determine the
diffusion of probe molecules in such catalysts by means of inverse
gas chromatography. This procedure is described in detail, and its
relevance in FCC is illustrated by several examples. It is shown that
catalytic properties of FCC catalysts can be rationalized with the
diffusion coefficient parameter in cases where traditional analytical
tools (nitrogen sorption and X-ray diffraction) reach their limits.
The fluid catalytic cracking (FCC) unit is the primary hydrocarbon conversion unit in the modern petroleum refinery. It uses heat and catalyst to convert a variety of high molecular weight feed types (eg, gas oils, cracked gas oils, deasphalted gas oils, and atmospheric/vacuum resids) into lighter, more valuable products such as gasoline, light fuel oil, and petrochemical feedstocks such as propylene and butylene. This article reviews the role of catalyst in the fluid catalytic cracking process. The design of catalyst, catalyst poisons, and the effect of catalyst on product yields and selectivity are covered. Also, the role of catalytic additives in maximizing light olefins and in controlling emissions is discussed. In addition, the importance of catalyst testing is covered, along with unconventional feedstocks and processes that are extending the role of FCC catalyst to areas beyond the original FCC process scope of converting heavy petroleum feedstocks into transportation fuels.
A fluid catalytic cracking (FCC)
catalyst is used in refineries
to upgrade crude oil into valuable products. To fulfill the increasing
demand for propylene, additives are used to boost propylene production.
The hydrothermal conditions in a FCC unit gradually deactivate the
Y-zeolite in the catalyst and the ZSM-5 zeolite in the additive by
a dealumination of the framework structure. By powder X-ray diffraction,
the change in the lattice parameter of the Y-zeolite over time is
used to monitor the deactivation process. In this paper, we have shown
that with a combination of powder X-ray diffraction and Rietveld analysis
we can monitor the deactivation of ZSM-5. The lattice parameters measured
for ZSM-5 are used to calculate the unit cell volume, which shows
a good correlation with physical properties, such as total acidity
and surface area, and the catalytic properties of ZSM-5 based additives.
The data demonstrate that the technology can be applied to both laboratory
and field deactivated ZSM-5 based additives.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.