The mathematical simulation of a Loop-Venturi Reactor (LVR), batch and continuous reactors was investigated for the reaction engineering of a gas-liquid (or on a suspended catalyst) process. A new model describing the LVR system for different operation modes is proposed. The model allows to calculate the liquid and gas dissolved concentration in the reaction mixture during the reaction. The model has been analyzed for a commercial nitrozation process of diphenilamine (DPHA) in threechlorethylene (TCHE), The experiments were carried out in a pilot continuous LVR with a volume of 181. Separately measured N2O3 dissolution in the solvent and kinetic studies of the reaction as well as proposed mathematical models allow to describe adequately experimentally obtained data of the gas-liquid process during the reaction pass when the equation rate is zero order with respect to DPHA and first order with respect to nitrogen oxides. The temperature range varied between 10 and 30 degrees C, and a total pressure of the gas mixture (NG-NO2 = 1-1) was 0.1 MPa.