Production of Isooctane from Isobutene: Energy Integration and Carbon Dioxide Abatement via Catalytic Distillation

Isooctane is a valuable octane enhancer for gasoline and the primary component of aviation gasoline, also known as Avgas, because of its high antiknock quality. Conventional industrial processes for isooctane production involve the steps of dimerization of isobutene, dimer separation, and hydrogenation. The efficacy of catalytic distillation (CD) and its merits, in terms of energy savings and reduction of greenhouse gas emissions, for the production of isooctane are quantitatively presented. The feed considered for the isooctane production is composed of isobutene (C-4) and inerts (isopentane) produced in refineries as byproducts of steam cracking of naphtha and light gas oil. Process flow sheets for the two routes for the production of isooctane, with and without CD, are modeled. The conventional industrial flow sheet composed of a dimerization reactor, distillation column, and a hydrogenation reactor (configuration A), is simulated using Aspen Plus. The intensified process flow sheet comprising a CD column for the dimerization, hydrogenation, and separation (configuration B) is modeled using gPROMS. A validated, nonequilibrium, three-phase model is developed in a gPROMS environment and is used to quantify the energy savings and reduction of carbon dioxide emissions achieved using a CD column for the intensified process. Results demonstrate CD to be a promising candidate to replicate the conversions and product purity obtained in the conventional process while resulting in significant energy savings, more efficient utilization of isobutene feed, and reduced carbon dioxide emissions.