关键词: 烷基化, 混合丁烯, 反应动力学, 碳正离子, 动力学模型, 参数估值

Abstract:

The alkylation kinetics of isobutane with mixed butenes using sulfuric acid as catalyst was investigated by batch experiments at temperatures from 276.2 K to 285.2 K under the conditions of industrial interest. With the decrease of reaction temperature, both the production of main product trimethylpentanes (TMPs) and RON of alkylates increased, and byproducts dimethylhexanes (DMHs) changed a little, but heavy ends components (HEs) reduced significantly. By using the alkylation kinetics model based on the classic carbonium ion mechanism, the concentration profiles with time regarding three groups of key alkylates, including TMPs, DMHs, and HEs, were compared against experiments. The regression results showed that the kinetics model fitted experimental data very well. An anti-Arrhenius behavior was found in the chain initiation step of the addition reaction of H⁺ to isobutene, and the apparent activation energies of itself and the reverse reaction were 45.14 kJ·mol^-1 and 41.44 kJ·mol^-1. The calculation of reaction rates of the TMPs⁺ and DMHs⁺ forming steps was added, and most of the reaction rates of chain transfer and chain termination reactions remained the same as those in literature.

Key words: alkylation, mixed butenes, reaction kinetics, carbocation, kinetics modeling, parameter estimation