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A comparison was performed between the performances of a MAT-type reactor (flow fixed bed) and a CREC Riser Simulator reactor (batch fluidized bed) in the conversion of two VGO feedstocks (aromatic and paraffinic types) over three commercial equilibrium FCC catalysts under similar conditions. In both units the reaction temperatures were 500 and 550 °C. The catalyst to oil relationships were from 2.3 to 6.2 (cumulative) and 6.2, and the times were from 15 to 40 s (time on stream) and from 5 to 30 s (reaction time) in the MAT reactor and the CREC Riser Simulator reactor, respectively. A comparison of the product yield structure in each unit at the same conversion showed that they were very different due to the significant differences in the contact between reactants and catalyst and operative modes. Results were compared in terms of VGO conversion and the yields of the most important hydrocarbon groups LPG, gasoline, and coke. Some advantages were observed with data from the CREC Riser Simulator reactor, derived from the fact that yields are in general closer to commercial values, mainly concerning gasoline and coke. The yields of the main hydrocarbon groups also followed linear behaviors in this reactor, thus being easier to analyze, as selectivities did not depend on the conversion reached. On the contrary, yields showed a strong dependency on conversion in the MAT reactor, particularly in the case of gasoline and coke. The high coke yield in the first moments of the experiments in the MAT reactor could lead to modifications in the selectivities to certain reactions and products.

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A comparison was performed between the performances of a MAT type reactor (flow fixed bed) and a CREC riser simulator reactor (batch fluidized bed) in the conversion of two VGO feedstocks (aromatic and paraffinic types) over three commercial equilibrium FCC catalysts, under similar conditions. In both units the reaction temperatures were 500 and 550 °C. The catalyst-to-oil relationships were from 2.3 to 6.2 (cumulative) and 6.2, and the times were from 15 to 40 s (time on stream) and from 5 to 30 s (reaction time) in the MAT reactor and the CREC riser simulator reactor, respectively. Results were compared in terms of the composition of the naphtha, in view of its contribution to the gasoline pool. Advantages were observed with data from the CREC riser simulator reactor, mainly derived from the fact that naphtha yields were, in general, closer to commercial values and showed a stable primary product behavior. Thus, they are easier to analyze as naphtha selectivities did not depend on the conversion reached. On the contrary, naphtha yields in the MAT reactor showed a maximum as a function of conversion. The comparison of the product distributions observed in the naphthas from each unit at the same conversion level showed that they can be very different; the naphtha obtained in the CREC riser simulator reactor was more paraffinic and less aromatic than the one obtained with the MAT reactor, and the proportions were similar to commercial values. Ranks of catalysts based on the various hydrocarbon fractions observed in the naphtha from each setup also differed in most of the cases. The differences in the results could be the consequence of notoriously different contact between reactants and catalyst and operative modes in each reactor, then impacting on the complex set of reactions occurring in FCC.

The feasibility of reconversion of a highly olefinic cut (OLEF; 60−110 °C), obtained from the bottoms of depentanizer columns used to separate the C5 fraction from fluidized catalytic cracking (FCC) naphtha, was studied under realistic FCC conditions over two equilibrium commercial catalysts. A riser simulator reactor was used at 500 and 550 °C, a catalyst-to-oil ratio of 5.6, and short reaction times of up to 15 s to assess (a) the crackability and the products of the conversion of the cut OLEF, (b) the conversion of a standard vacuum gas oil feed (VGO) to be used as a reference, and (c) the conversion of a mixture with a mass ratio of 20:80 OLEF−VGO. The gas fraction in the conversion of OLEF showed high yields of propene and isobutane, while aromatics and i-paraffins appeared among products with the same range of molecular weights as the feedstock, thus determining a research octane number value in the gasoline cut that is higher than the feedstock's. Olefins showed to be converted selectively. The conversion of the mixture OLEF−VGO showed the following main characteristics that differ from the standard operation (VGO feedstock):  (i) an increase in the yield of gasoline, which is higher than the one expected from the separate conversion of equivalent masses of the individual feedstocks, (ii) an increase in the yield of liquified petroleum gas and some individual hydrocarbons, like propene or isoamylenes, and (iii) a better octane-barrel balance in gasoline. The particular characteristics of each catalyst (activity and hydrogen transfer capability) reflected clearly on the product distributions obtained in the conversion of the various feedstocks. This recycling option appears as very interesting because it could contribute to improve the refinery's economy through the improvement of different issues.