Zone Reactor
Like the Solid Reactant process, the Zone Reactor uses proprietary materials based on doped metal oxides that are easily cycled between an oxide and bromide form to capture HBr and subsequently regenerate bromine. In the Zone Reactor all steps of the process can take place in a single reactor vessel with three zones. In the first zone, solid reactant in the bromide form is reacted with the oxygen in air to produce bromine while at the same time transforming the solid reactant in the oxide form. In a second zone, the bromine is reacted with methane producing methyl bromide. In a third zone, the methyl bromide reacts over a catalyst to produce the desired products and the HBr byproduct is captured by reaction with the oxide form of the solid reactant, transforming it to the bromide form. When the transformation of the solid reactants in zone 1 and zone 3 is substantially complete, the feed of air is switched from zone 1 to zone 3, thereby allowing the process to continue with roles zones 1 and 3 interchanged. By cycling between feeding air to zone 1 and zone 3, the process can be run in a continuous fashion.
The Zone Reactor configuration eliminates the need for bromine to ever leave a single reactor vessel, resulting in enhancement to safety, process simplification, and capital cost reduction.
In the simplest form of the Zone Reactor the solid reactant plays the role both of capturing HBr and catalyzing the desired coupling reaction. Such materials are called “cataloreactants”. The coupling reaction can also take place over a multifunctional material or using separate catalyst and solid reactant beds within zones 1 and 3.