ABSTRACT
School of Chemical Engineering and Industrial Chemistry, The University of New South Wales, UNSW Sydney 2052, Australia
m.wainwright@unsw.edu.au
Abstract The oxidative dehydrogenation of ethanolamine to sodium glycinate in 6.2 M NaOH was investigated using unpromoted and chromia promoted skeletal copper catalysts at 433 K and 0.9 MPa. The reaction was first order in ethanolamine concentration and was independent of caustic concentration, stirrer speed and particle size. Unpromoted skeletal copper lost surface area and activity with repeated cycles but a small amount of chromia (ca. 0.4 wt%) resulted in enhanced activity and stability. Introduction The oxidative dehydrogenation of ethanolamines to their corresponding aminocarboxylic acids is of considerable commercial interest for the production of agricultural and other chemicals. The reactions can be carried out in an alkaline environment without a catalyst but the reaction is slow with low yields (1). The first attempts to develop a catalyst were carried out with water absent. Chitwood (2) disclosed that cadmium oxide exhibited the highest activity but yields were moderate and the use of cadmium oxide is highly undesirable due to its toxicity. Copper was found to exhibit an activity only slightly less than that of cadmium oxide but the duration of maximum catalytic activity was shorter. Goto et al. (1) invented a new method in which copper, or a mixture of copper and zirconium compounds, was used in the presence of aqueous NaOH or KOH to manufacture aminocarboxylic acid salts more quickly with very high yields under milder reaction conditions. More recent patents carry claims for improved copper catalysts and for their use to produce other target compounds in a similar way (3-6).
