Among other fuel additives — such as MTBE, ETBE, or TAME — 2-methoxy-2-methyl heptane (MMH) can increase the fuel octane number and reduce the CO emission. MMH can be obtained through the exothermal etherification of 2-methyl-1-heptene and methanol. Lately, many researchers have developed more and more efficient processes considering the kinetics corresponding to an endothermal reaction. However, in this work we demonstrate that the reaction is actually quite exothermal, and this has strong impact on the designed process. Also, the vapor–liquid equilibrium data predicted by UNIQUAC model for 2-methoxy-2-methyl heptane and 2-methyl-2-heptanol mixture reveals that product purification is more difficult, and it requires more energy to recover and obtain MMH with high purity. Considering these aspects, the 54.87 ktpy process developed in this paper is more realistic and energy intensive (1.82 kW h/kg MMH), with a TAC of 5.3 M$/year. The controllability of the process is proven for ±20% changes of 2-methoxy-2-methyl-heptane production rate.

There are only a handful of process control structures applied to the neat operation of both homogeneous and heterogeneous reactive distillation, for two-reactants / two-products one-reaction systems. All of these control structures employ inferential temperature control (or concentration analyzers) at some location in the column to balance the reaction stoichiometry. This original study proposes a new class of control structures applicable to heterogeneous reactive distillation. The novel idea, common to all control structures, is based on monitoring the inventory of the reactant involved in the heterogeneous azeotrope. The organic reflux (or the organic reflux / aqueous distillate ratio) is used to detect the excess or deficiency of the reactant, based on which the fresh feed rate is adjusted such that the reaction stoichiometry is balanced. This control philosophy is simple and easy to implement in different ways as illustrated by several case studies. The performance of the proposed control structures depends on the system studied. For some systems, the performance is better, as good or nearly as good as that of the literature control structures. But for other systems, the performance is poor or the structure even fails to control the process, due to the insufficient feedback from inventory measurements.