Influência do nível de metais contaminantes no desempenho catalítico do catalisador de equilíbrio de FCC

Abstract

The fluid catalytic cracking (FCC) is one of the most profitable refining processes, since it contributes effectively to the production adjustment by transforming lower value-added chains into fractions such as naphtha and LPG. This process consists in the cracking of high molecular weight hydrocarbons, present in gas oils and residues, by the action of zeolite Y based microspherical catalyst at high temperatures. It takes seconds for this reaction to occur and the catalyst undergoes deposition of coke, which is removed by combustion in the thermal regeneration stage under air flow, generating the FCC equilibrium catalyst (e-cat). In this process, the e-cat moves cyclically and its repeated contact with the regenerator s hydrothermal atmosphere associated with contaminating metals, leads to its progressive deactivation in an irreversible way. To recover the e-cat activity and compensate losses in the process, the circulating inventory is fed periodically with fresh catalyst, which causes age variation of the particles that compose this inventory. The objective of this work was to evaluate the influence of nickel and vanadium concentration level of commercial e-cats on their catalytic performance when tested using real refinery feed. The samples were characterized in terms of their chemical composition and through statistical methods, were classified into three groups that are distinguished by the level of contamination by metals. It was selected representative samples of the entire range of contaminants for each group. Besides measurements of its textural properties, the samples were submitted to catalytic evaluations at Advanced Catalytic Evaluation (ACE) unit, with the same gas oil feed and the same cracking conditions. In order to investigate the effect of particle aging on catalyst performance, an e-cat sample was fractionated using the density difference separation method. The obtained fractions were also evaluated in terms of their textural properties and catalytic performance in ACE unit. From the results obtained, it was possible to observe, for different levels and ranges of metal contamination, the impact on the catalytic performance, mainly in conversion and in the coke and hydrogen yields, not only of the metals variation, focus of this work, but also of other variables as matrix effect and the interaction between metals.