First‐Principles Design of Highly Active and Selective Catalysts for Phosgene‐Free Synthesis of Aromatic Polyurethanes

Abstract

Catalyst design: First principles calculations predict that phosgene can be substituted by dimethyl carbonate (DMC) in the carbamoylation of aromatic amines when using a CeO2 catalyst preferentially exposing the low energy {111} facet. Experimental results confirm the theoretical predictions, and CeO2 nano‐octahedra terminated by low energy {111} facets show high activity and selectivity toward the desired dicarbamoylated product.

Methyl N-phenyl carbamate synthesis over Zn/Al/Ce mixed oxide derived from hydrotalcite-like precursors

“…15 However, due to the high reactivity of the intermediates decomposed from DMC, carbamoylation and methylation proceed simultaneity during the aminolysis reaction, which, respectively, leads to the formation of MPC and N-methylaniline (NMA) and/or N,N 0 -dimethylaniline (DMA), as shown in Scheme 1. 2,[16][17][18] Thus, developing catalysts with high activity is quiet necessary so as to enhance the selectivity as well as yield of MPC.…”

Carbon2Polymer – Chemical Utilization of CO2 in the Production of Isocyanates

“…The oxidative carbonylation of primary aromatic amines to generate the corresponding carbamates is well known , and is also the key step from TDA to TDC in the alternative (CO 2 ‐based) route towards TDI as high‐value polymer precursor (Scheme ). Apart from this, the synthesis of TDC via reductive carbonylation of nitro compounds and reactions of amines with organic carbonates , CO 2 or corresponding ureas with alcohols are competing concepts – but do not address our needs in such a completive way.…”

Bridging the gap between insightful simplicity and successful complexity: From fundamental studies on model systems to technical catalysts

“…Zhou et al [113] first reported that CeO 2 nanorods, exposing preferentially {0 0 1} and {1 1 0} facets, showed a substantially higher surface-specific activity for CO oxidation than CeO 2 nanocrystals of irregular shapes, for which the majority of the surface facets corresponded to more compact {1 1 1} planes. More recently, Laursen et al found CeO 2 octahedra nanocrystals terminated by {1 1 1} facets to exhibit the highest activity and selectivity toward the desired dicarbamoylated products in the carbamoylation of aromatic amines with dimethyl carbonate, a reaction which is crucial in potential ''greener,'' phosgene-free processes to produce polyurethanes [114]. Given that many oxides play a non-innocent role when applied as support material in metal catalysts, similar facetdependent catalytic properties have been revealed for metal nanoparticles deposited on morphologically tailored oxide supports.…”