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

Abstract

The presented work evaluates the implementation of adsorption and desorption experiments with Cl2 over carbon materials towards the development of more active and stable catalysts for industrial phosgene synthesis. By using a soft templating method as a tool, ordered mesoporous carbon materials with tunable porosity, surface area, and degree of graphitization were synthesized and utilized as model system. The Cl2 adsorption/desorption properties of these materials were studied and compared to commercial activated carbon. To draw correlations between Cl2 adsorption/desorption behavior and catalytic performance, the materials were further tested in the phosgene formation in a plug flow reactor. However, the chemical reaction of Cl2 with carbon during the adsorption/desorption experiment hinders a direct correlation.

A Theoretical Study on the Phosgenation of 2,4-Toluenediamine (2,4-TDA)

“…The distillation residue formed is hydrolyzed at <230 °C under absolute pressures of less than 30 bar [ 5 ]. For these process, the reactive phosgene compound is produced by passing purified carbon monoxide and chlorine gas through a bed of porous activated carbon [ 6 , 7 ].…”

Phosgene formation via carbon monoxide and dichlorine reaction over an activated carbon catalyst: Towards a reaction model

“…A dichlorine capacity of 4.3  0.4 mmol Cl2 g -1 cat represents the total chlorine capacity of the catalyst, carbon as a reference material [14]. The extent of Cl2 adsorption exhibited a temperature dependence.…”

“…The extent of Cl2 adsorption exhibited a temperature dependence. For Cl2 adsorption at 683 K, EDAX analysis showed residual chlorine content to be in the range 4-8 wt % [14].…”

“…chlorine adsorbed in high energy sites) would not be detectable in this sequence of TPD measurements. In their study of Cl2 adsorption on ordered mesoporous carbon materials, Bähr et al report on a Cl2 desorption feature at 683 K after Cl2 adsorption at 623 K [14].…”

Composite Carbon Foams as an Alternative to the Conventional Biomass-Derived Activated Carbon in Catalytic Application

“…Template carbonization is the simplest method, and uses foam templates such as polyurethane (PU), melamine and zeolite foams [ 2 , 3 , 4 ]. By choosing a suitable template, porous materials can be synthesized with defined porosity, surface area, particle size, and crystallinity [ 5 ]. Carbon foams are used extensively as electrodes in energy storage devices, for heavy metal and organic dye removal, and for CO 2 adsorption [ 6 , 7 , 8 , 9 ].…”