Christian Schrage

A new route to porous monolithic organic frameworks via cyclotrimerization

Cyclotrimerization of bifunctional acetyl compounds is used to obtain highly porous organic frameworks. Syntheses in solution induced by silicon tetrachloride result in highly disperse powders while syntheses in molten 4-toluene sulfonic acid result in polymeric monoliths with a hierarchical pore structure containing micro- and macropores allowing for direct impregnation of textiles with a porous polymer. The materials show specific BET surface areas up to 895 m2 g−1 and large pore volume (1.99 cm3 g−1) combined with a highly hydrophobic character. The amorphous materials are thermally stable below 300 °C in air and show no decomposition effects in aqueous environment. These outstanding properties in combination with the opportunity to generate shapes of any kind desired for an application render the materials as highly promising for application in air filtration systems and individual protection, as well as gas storage and separation.

Flexible and Transparent SWCNT Electrodes for Alternating Current Electroluminescence Devices

The application of transparent single-walled carbon nanotube (SWCNT) electrodes in rigid and flexible alternating current electroluminescence (ACEL) devices is demonstrated. SWCNT thin-film electrodes (50-160 nm) were made using a spray-coating process suitable for adjusting the transparency and sheet resistance. The dispersing procedure was optimized by comparing the transparency to sheet resistance ratio (T/R) of the electrodes. The emission intensity was as high as that for indium-tin oxide (ITO)-based ACEL devices with transparencies comparable to those of ITO-coated polymer slides.

Assessment of hydrogen storage by physisorption in porous materials

As a basis for the evaluation of hydrogen storage by physisorption, adsorption isotherms of H2 were experimentally determined for several porous materials at 77 K and 298 K at pressures up to 15 MPa. Activated carbons and MOFs were studied as the most promising materials for this purpose. A noble focus was given on how to determine whether a material is feasible for hydrogen storage or not, dealing with an assessment method and the pitfalls and problems of determining the viability. For a quantitative evaluation of the feasibility of sorptive hydrogen storage in a general analysis, it is suggested to compare the stored amount in a theoretical tank filled with adsorbents to the amount of hydrogen stored in the same tank without adsorbents. According to our results, an “ideal” sorbent for hydrogen storage at 77 K is calculated to exhibit a specific surface area of >2580 m2 g−1 and a micropore volume of >1.58 cm3 g−1.

Decomposition of 2-chloroethylethylsulfide on copper oxides to detoxify polymer-based spherical activated carbons from chemical warfare agents

For the decomposition of chemical warfare agents, a hybrid material concept was applied. This consists of a copper oxide-containing phase as a component with reactive functionality supported on polymer-based spherical activated carbon (PBSAC) as a component with adsorptive functionality. A corresponding hybrid material was prepared by impregnation of PBSAC with copper(II)nitrate and subsequent calcination at 673K. The copper phase exists predominantly as copper(I)oxide which is homogeneously distributed over the PBSAC particles. The hybrid material containing 16 wt.% copper on PBSAC is capable of self-detoxifying the mustard gas surrogate 2-chloroethylethylsulfide (CEES) at room temperature. The decomposition is related to the breakthrough behavior of the reactant CEES, which displaces the reaction product ethylvinylsulfide (EVS). This leads to a combined breakthrough of CEES and EVS. The decomposition of CEES is shown to occur catalytically over the copper-containing PBSAC material. Thus, the hybrid material can even be considered to be self-cleaning.

Supported ionic liquid phase (SILP) materials for removal of hazardous gas compounds – efficient and irreversible NH3 adsorption

Novel supported ionic liquid phase (SILP) gas purification materials have been developed to remove ammonia irreversibly from an ambient gas flow of nitrogen (1000 ppm NH3 in N2, wet and dry). In the applied SILP materials, thin films of imidazolium based ionic liquids and ionic solutions of metal complexes, namely [C8C1Im][NTf2], [C8C1Im][NTf2]/Cu(NTf2)2, [C8C1Im][NTf2]/Co(NTf2)2 and [CnC1Im]Cl/CuCl2 (n = 2, 4, 8), were dispersed onto the large surface area of polymer-based spherical activated carbon supports. For the [CnC1Im]Cl/CuCl2 (n = 2, 4, 8) based SILP materials the use of a humid gas flow significantly enhances NH3 absorption as demonstrated by a clear increase of breakthrough times. The irreversibility of the ammonia sorption and the broadband capability (e.g. Cl2, H2S and cyclohexane) of the prepared SILP absorber materials are reported and compared to typical standards for gas purification adsorber materials (ABEK regulations).