Concentration and Mixing Effects on the Production of Amine Hydrochloride Salts in a Confined Impinging Jet Reactor

Abstract

A Confined Impinging Jet Reactor (CIJR) was used to react 4, 4’-methylene dianiline (MDA) with hydrogen chloride (HCl) in order to study formation of the aminehydrochloride (AHC) salts, unwelcome byproducts in the manufacture of polyurethanes. The effects of several processing variables (local concentration of MDA and HCl and the intensity of local mixing) on the formation of AHC salts were studied. The precipitated solids were characterized using a wide range of analytical techniques: elemental analysis, FTIR, TGA, DSC, optical microscopy, SEM and EDX. The effects of each process variable on the solid compounds and composition, thermal properties, morphology and average particle size are discussed. Results show that formation of AHC salts more than anything depends on local concentration of MDA and it dominates the structure of product in terms of formation of MDA.HCl or MDA.2HCl. Mixing intensity affects product purity of and evenness of shape and average size.