Preparation of Spherical Rhodium Triiodide Based on Reaction Crystallization

Abstract

Reaction crystallization/precipitation in the industrial practice has a widely applications. To obtain easily solid-liquid separation process, it is necessary to control the morphology and the particle size of the product. The process of preparation rhodium(III) triiodide (RhI₃, the catalyst precursor for the Monsanto process) based on the different procedures 1, 2 and 3 have been optimized in order to minimize the cost of solid-liquid separation. The morphology and size of RhI₃ particles were investigated by scanning electron microscope. The results show that with the change of the physicochemical properties the critical parameters of control the morphology and size of the precipitation were different. The particle morphology based on the three routes was similar to spherical agglomeration and the particle diameter was ca. 20 μm. Furthermore, the filterability of the precipitation has also been greatly improved. Further research to find out why and how these factors working in industrial practice is underway.