Adjustment of W-O-Zr Boundaries Boosts Efficient Nitrilation of Dimethyl Adipate with Ammonia on WO x /ZrO 2 Catalysts.

In this study, a tungstated zirconia (WO x /ZrO 2 ) catalyst was developed for the continuous synthesis of adiponitrile (ADN) by gas-phase nitrilation of dimethyl adipate (DMA) with NH 3 . The highest TOF ADN could be reached on WO x /ZrO 2 bearing ∼1D WO x species (highly dispersed and discontinuous status) at the surface, which, however, delivered the poorest selectivity toward nitrilation (S ADN+MCP ). In comparison, both efficient and selective transformation of DMA to ADN was achieved by fabricating WO x /ZrO 2 with continuously distributed oligomeric WO x species (∼2D) at the surface, either by varying the dosage of the W-reagent in the preparation of WO x (m)/ZrO 2 or by doping a proper amount of the Mn element into WO x (5.0)/ZrO 2 , bearing WO 3 NPs. Furthermore, the in situ diffuse reflectance infrared Fourier transform spectroscopy investigations of both independent and competitive adsorptions of ester functionality and NH 3 over W-O-Zr, W-O-W, and Zr-O-Zr boundaries at the surface clarified the synergistic effect of these species in the activation of DMA/NH 3 and thereby nitrilation.