Developing the technology for producing highly concentrated iso -butylene

The technology used at Russian plants for the recovery of polymerization-grade iso-butylene is based on synthesizing tert-butanol through the hydration of iso-butylene incorporated into raw hydrocarbon fractions with the subsequent separation and decomposition of tert-butanol. The hydration of iso-butylene is performed in reactive extraction reactors with countercurrent initial reagents on a molded sulfocationite catalyst. In this paper, a version of the process performed in a flow reactor at near-stoichiometric ratios of reagents is proposed in the context of modernizing the existing technology. The dependence of iso-butylene conversion and the amount of by-products (dimers, sec-butanol) on the type of hydrocarbon feedstock and the process parameters is studied. The iso-butane-iso-butylene fraction (IIF) and the butylene-iso-butylene fraction (BIF) are used as feedstocks. It is shown that iso-butylene conversion is lower for the BIF feedstock, and the concentration of by-products is higher than for the IIF feedstock. A tert-butanol synthesis flowsheet is proposed that includes flow and reactive extraction reactors and allows us to increase the capacity of an existing plant with a simultaneous reduction in the process’s overall energy consumption due to the production of a highly concentrated tert-butanol solution at the outlet of the flow reactor, and to obtain iso-butylene with a purity of no less than 99.99 wt %.