Structural properties and chemical bonds in double metal cyanide catalysts

摘要: Double metal cyanide (DMC) catalysts are commonly applied at industrial ring-opening polymerization of the epoxides, being initial stage polyurethanes manufacturing route. This group is frequently used in industry, but knowledge on molecular nature their high activity and selectivity limited to some phenomenological hypotheses based overall chemical premises. To shine light relation between structural properties DMC activity, complementary X-ray powder diffraction, photoelectron spectroscopy, energy dispersive spectroscopy absorption studies were performed. The comprehensive characterization catalyst synthesized from ZnCl2 potassium hexacyanocobaltate(III) solution, presence organic ligand (tBuOH), confirmed that a significant part material reveals features non-crystalline structure. Extended fine structure (EXAFS) analysis established only Zn atoms active metallic centers catalyst. coordination around was changed octahedral reference tetrahedral catalysts, Cl detected near atoms, no amount oxygen detected, which agrees with XPS analysis. performed experimental give direct evidence for model deduced by Zhang et al., calculation Wojdel al. Moreover, generally accepted formula Zn3[Co(CN)6]2•xZnCl2•ytBuOH•zH2O describing this not valid, because none compounds XRD or EXAFS techniques. Regarding catalyst, we conclude content very important, also fraction phase, formation stimulated ligand. may offer easier access center Cl. Copyright © 2015 John Wiley & Sons, Ltd.