Isobutane/2-butene alkylation over faujasite type zeolites in a slurry reactor. Effect of operating conditions and catalyst regeneration Original Research Article

The isobutane/2-butene alkylation has been catalysed by acidic cubic faujasites (H-FAU and CeY-98) and a hexagonal faujasite (H-EMT) in a semibatch slurry reactor. H-EMT exhibited the best results during the reaction with respect to an improved deactivation profile and moderate loss of alkylate selectivity compared to both CeY-98 and H-FAU. Additionally, H-EMT proved to be regenerable. The different catalytic behaviour between H-EMT and H-FAU has been discussed in terms of differences in their crystal structure. Furthermore, we have focused on the influence of isobutane:2-butene molar ratio and temperature (simultaneously varied) on the catalytic behaviour at constant butene WHSV fed to the slurry reactor at optimum stirring conditions. CeY-98 was used as a model catalyst and the results were treated statistically by principal component and partial least square analyses. The dependence of alkylate selectivity as well as yield related to temperature (T) and isobutane:2-butene molar ratio (M) were found to be: Selectivity = 0.53 + 0.017 [M − 12.5] + 0.0003 [T − 90] + 0.0004 [T − 90] [M − 12.5]; Yield = 0.55 + 0.016 [M − 12.5] + 0.001 [T − 90] + 0.0004 [T − 90] [M − 12.5], within the employed parameters (T∈80–100°C, M∈5–20). Both equations showed optima at low butene concentrations, while the temperature was of minor importance. A high stirring speed was essential to achieve optimal reaction conditions enlarging the alkylate yield and selectivity.