The leidenfrost reactor: a new general purpose direct-cooled reactor and its use for low temperature polymerizations

Abstract

Inspired by the Leidenfrost phenomenon a direct-cooled general purpose low-temperature reactor has been developed and its applicability for polymerizations was demonstrated. The Leidenfrost reactor is efficiently cooled by introducing relatively inexpensive liquid N2 (LN2) directly into the bulk of polymerization charges and the rapid evaporation of the coolant chills the system. The gaseous N2 generated provides an inert gas blanket that protects moisture and/or air sensitive charges. The installation of expensive cooling jackets or coils is superfluous and stirring is optional. The virtually complete recovery of cooling energy is possible. In the Leidenfrost reactor the LN2 heat sink is virtually in contact with the heat source so that the path of heat transfer is practically nil. Reactor fouling is eliminated which is of particular interest in butyl rubber manufacture. Constant temperature control is readily accomplished by regulating the input rate of the coolant and undesirable temperature jumps are suppressed. Continuous operation is possible. The operation of the Leidenfrost reactor is illustrated by the polymerization of isobutylene at −60°C.