Nitrogen Modified Carbon Nano-Materials as Stable Catalysts for Phosgene Synthesis

Abstract

The carbon-catalyzed reaction of Cl2 and CO constitutes the most important industrial route to phosgene. Although defects in carbon lead to surface chemical reactions, direct polarization of C-heteroatom bonds induces a more successful Cl2 catalytic activation, the rate-determining step in the overall catalytic cycle. The interplay between the electron-donating and -withdrawing ability of the incorporated nitrogen substituents on the formation and stabilization of active sites was examined by X-ray photoelectron and Raman spectroscopy. Mechanistic studies indicate that the polarized Cl2 induced by the direct interaction of Cl2 with a strongly electron-deficient carbon site in close proximity to a nitrogen substituent is essential for phosgene production. Nitrogen substitution into ordered carbon materials led to very active and stable carbon catalysts for COCl2 synthesis.

Opening the internal structure for transport of ions: improvement of the structural and chemical properties of single-walled carbon nanohorns for supercapacitor electrodes

“…For r-SWCNH-ox-1.5, we observed the appearance of N-H bonds at 399.8 eV, pyrrolic or amine moieties at 400.2 and 400.6 eV, and quaternary N at 401.8 eV. 64,70,71 We observed the hydrophilization of the SWCNH surface by the creation of surface oxides. The ratio of C 1s/O 1s peaks decreases rapidly aer a short oxidation process (aer 0.5 h), from 15.110 to 4.143, and subsequently changes during a longer oxidation time, reaching a value of 2.603 for SWCNH-ox-3 (Table 2) and a value of 4.05 for r-SWCNH-ox-1.5.…”

A Metal-Free Carbon-Based Catalyst: An Overview and Directions for Future Research

“…Gupta et al [178] reported an effective method for the preparation of phosgene gas by nitrogen-modified carbon nanomaterials, which was derived from the N-modified polymer material. The incorporation of active nitrogen into graphitic carbon materials resulted in the formation of porous carbon catalysts that are active and stable for the generation of phosgene (COCl 2 ) with very high selectivity.…”

Cl2 Adsorption and Desorption over Ordered Mesoporous Carbon Materials as an Indicator for Catalytic Phosgene Formation

“…Although the process of phosgene production [3,4], the kinetics of the reaction [5][6][7][8] and catalytic active commercial activated carbons for this reaction are well investigated [9][10][11], there are only a few mechanistic studies. Noteworthy are the studies by Lercher and co-workers, who propose an Eley-Rideal mechanism for the formation of phosgene [12][13][14]. There, the Cl 2 forms a charge-transfer complex with the activated carbon surface, before the Cl-Cl bond is cleaved by a CO molecule attacking from the gas phase.…”