Coke steam reforming in FCC regenerator: A new mastery over high coking feeds

[EN] One of the crucial problems of processing residual feeds in the FCC is their high coking tendency, which limits their use in the FCC and requires them to be mixed with lighter feeds to be processed in conventional FCC units. A step-out improvement of the FCC process to use in processing heavy feeds is presented, where the heat balance in the unit is maintained by removing the high coke-on-catalyst by a combination of coke combustion and reforming, i.e., coke steam reforming (CSR) in the regenerator. This option enables using feeds with more than 10% Conradson Carbon while still maintaining the possibility to control the heat balance in the unit without using partial combustion or catalyst coolers. Although the Equilibrium catalyst has little CSR activity, we have found that hydrotalcite materials, besides having an excellent catalytic cracking selectivity for heavy feeds, also have significant CSR activity. We have demonstrated that CSR can be performed together with combustion at conditions found in the FCC regenerator so that the regenerator temperature remains within traditional limits despite higher coke-on-catalyst, and the coke on the catalyst is nearly completely removed. While the reaction rate at higher temperatures seems to obey first order, steam reforming coke removal kinetics at lower (750 degrees C) temperatures seem more complex due to the heterogeneous nature of coke.The authors thank BP Products North America and Consolider-Ingenio 2010 (MULTICAT project) for their financial support and permission to publish this work.Corma Canós, A.; Sauvanaud ., LL.; Doskocil, E.; Yaluris, G. (2011). Coke steam reforming in FCC regenerator: A new mastery over high coking feeds. Journal of Catalysis. 279(1):183-195. https://doi.org/10.1016/j.jcat.2011.01.020S183195279

Quantum-chemical study of hydride transfer in catalytic transformation of paraffins on zeolites

Ab initio quantum-chemical cluster calculations demonstrate that the activated complexes of hydride transfer reaction in catalytic transformations of paraffins on zeolites very much resembles adsorbed nonclassical carbonium ions. The calculated activation energies for reactions involving propane and isobutane are in reasonable agreement with experimental data.</p

FCC testing at bench scale: New units, new processes, new feeds

As the FCC process has evolved over decades, several laboratory scale equipment have appeared to maintain a proper assessment of catalysts activity. Several laboratory equipments are available for simulating the FCC process, from the well known fixed bed, MicroActivity Test to newer, fluid bed or transported bed units. As well, a number of units have been created to simulate other parts of the process such as regenerator or stripper, The increased pressure for treating non-conventional feeds, from reprocessing gasoline to extra-heavy feeds or oils produced from biomass containing large amounts of heteroatoms, increase the needs to have a laboratory test which is as close as possible to the process so that data extraction from the laboratory test are simplified, thus less prone to errors or misunderstanding.Financial support by MICINN (Consolider-Ingenio 2010 MULTICAT) and MINECO (Project MAT2011-29020-0O2-02 and Subprogram for excellence Severo Ochoa, SEV 2012 0267) is gratefully acknowledged.Corma Canós, A.; Sauvanaud, LL. (2013). FCC testing at bench scale: New units, new processes, new feeds. Catalysis Today. 218-219:107-114. doi:10.1016/j.cattod.2013.03.038S107114218-21

A three-dimensional view of structural changes caused by deactivation of fluid catalytic cracking catalysts

Since its commercial introduction three-quarters of a century ago, fluid catalytic cracking has been one of the most important conversion processes in the petroleum industry. In this process, porous composites composed of zeolite and clay crack the heavy fractions in crude oil into transportation fuel and petrochemical feedstocks. Yet, over time the catalytic activity of these composite particles decreases. Here, we report on ptychographic tomography, diffraction, and fluorescence tomography, as well as electron microscopy measurements, which elucidate the structural changes that lead to catalyst deactivation. In combination, these measurements reveal zeolite amorphization and distinct structural changes on the particle exterior as the driving forces behind catalyst deactivation. Amorphization of zeolites, in particular, close to the particle exterior, results in a reduction of catalytic capacity. A concretion of the outermost particle layer into a dense amorphous silica–alumina shell further reduces the mass transport to the active sites within the composite

Catalytic cracking of n-alkane naphtha: The impact of olefin addition and active sites differentiation

An extended dual kinetic model allows to fit the n-heptane cracking results working in a wide range of reaction conditions. The duality of the model is provided by the contribution of monomolecular and bimolecular cracking mechanisms. It takes into account the role played by the olefins formed on the global cracking or added within the feed. Furthermore by means of this model and the kinetic parameters obtained when cracking n-heptane on ZSM-5, it has been observed that, while some characterization techniques show a homogeneous zeolite surface from the point of view of the active sites, rigorous kinetic experiments point to the possibility that the reactant sees a heterogeneous surface with, at least, two groups of cracking active sites. Those differentiated active sites give different cracking rates and different activation energies for the process and, in the case of ZSM-5, could be assimilated to sites pointing to the 10R channels and sites pointing into the crossing of the 10R channels, mainly due to differences in kid site location and confinement effects. (C) 2015 Elsevier Inc. All rights reserved.Financial support by the Ministerio de Economia y Competitividad of Spain (MINECO) [Programa Estatal (Project MAT2012-31657) and Programa Consolider-Ingenio 2010 (Project MULTICAT)] is gratefully acknowledged.Corma Canós, A.; Mengual Cuquerella, J.; Miguel Dolz, PJ. (2015). Catalytic cracking of n-alkane naphtha: The impact of olefin addition and active sites differentiation. Journal of Catalysis. 330:520-532. https://doi.org/10.1016/j.jcat.2015.04.020S52053233