Since the time of the industrial revolution, the atmospheric CO(2) concentration has risen by nearly 35 % to its current level of 383 ppm. The increased carbon dioxide concentration in the atmosphere has been suggested to be a leading contributor to global climate change. To slow the increase, reductions in anthropogenic CO(2) emissions are necessary. Large emission point sources, such as fossil-fuel-based power generation facilities, are the first targets for these reductions. A benchmark, mature technology for the separation of dilute CO(2) from gas streams is via absorption with aqueous amines. However, the use of solid adsorbents is now being widely considered as an alternative, potentially less-energy-intensive separation technology. This Review describes the CO(2) adsorption behavior of several different classes of solid carbon dioxide adsorbents, including zeolites, activated carbons, calcium oxides, hydrotalcites, organic-inorganic hybrids, and metal-organic frameworks. These adsorbents are evaluated in terms of their equilibrium CO(2) capacities as well as other important parameters such as adsorption-desorption kinetics, operating windows, stability, and regenerability. The scope of currently available CO(2) adsorbents and their critical properties that will ultimately affect their incorporation into large-scale separation processes is presented.

Adsorbent Materials for Carbon Dioxide Capture from Large Anthropogenic Point Sources

The Interaction of Water with Solid Surfaces: Fundamental Aspects Revisited

Since the discovery of organic azides by Peter Griess more than 140 years ago, numerous syntheses of these energy-rich molecules have been developed. In more recent times in particular, completely new perspectives have been developed for their use in peptide chemistry, combinatorial chemistry, and heterocyclic synthesis. Organic azides have assumed an important position at the interface between chemistry, biology, medicine, and materials science. In this Review, the fundamental characteristics of azide chemistry and current developments are presented. The focus will be placed on cycloadditions (Huisgen reaction), aza ylide chemistry, and the synthesis of heterocycles. Further reactions such as the aza-Wittig reaction, the Sundberg rearrangement, the Staudinger ligation, the Boyer and Boyer-Aube rearrangements, the Curtius rearrangement, the Schmidt rearrangement, and the Hemetsberger rearrangement bear witness to the versatility of modern azide chemistry.

Organic Azides: An Exploding Diversity of a Unique Class of Compounds

Ultrathin metal films and particles on oxide surfaces: structural, electronic and chemisorptive properties

Surface studies of supported model catalysts

http://w0.rz-berlin.mpg.de/hjfdb/pdf/133e.pdf

Hydroxyl groups on oxide surfaces: NiO(100), NiO(111) and Cr2O3(111)

We have investigated the adsorption of CO and CO2 on epitaxially grown Cr2O3(111) by means of EELS. LEED, ARUPS, NEXAFS and XPS. CO is found to adsorb on the oxide surface in an ordered (√3 × √3)R30° structure with the molecular axis oriented approximately parallel to the surface. CO2 on the other hand reacts with the chromium oxide to form a surface carbonate. Adsorption of CO, respectively reaction of CO2 only takes place on a clean, freshly flashed oxide surface. Preadsorption of oxygen leads to a surface which is rather inert to adsorption, likely due to electronic or steric reasons.

Adsorption and Reaction on Oxide Surfaces: CO and CO2 on Cr2O3(111)

Structural rearrangements of the (111) surface in the system Cr2O3(111)/Cr(110) as a function of temperature were investigated by means of low-energy electron diffraction (LEED) and electron energy loss spectroscopy (EELS). At room temperature, one observes a simple (1*1) LEED pattern of the clean (111) surface. If the temperature was lowered to 150 K a ( square root (3)* square root (3))R30 degrees superstructure was observed. The structure reached its maximum intensity at about 150 K substrate temperature. Below 150 K the superstructure vanished again and the simple (1*1) LEED pattern of the (111) surface was recovered at 90-100 K. Parallel to this, a considerable change in the electron energy loss spectra with varying temperature was observed. With the help of quantum-chemical cluster calculations the low-energy excitations in the range between 0.8 and 2.5 eV were assigned to local d-d excitations of Cr3+ ions at the Cr2O3(111) surface. Some of these peaks were quenched upon adsorption of gases such as CO, NO or CO2. We propose a model of two successive phase transitions the first of which is a disorder-to-order transition above 150 K whereas the second is an order-to-order transition below 150 K. The transitions may be driven by antiferromagnetic coupling of the surface chromium ions to those in the second layer.

/pdf/structural-rearrangement-and-surface-magnetism-on-oxide-1zpcwjkpzu.pdf

Structural rearrangement and surface magnetism on oxide surfaces: a temperature-dependent low-energy electron diffraction-electron energy loss spectroscopy study of Cr2O3(111)/Cr(110)

http://w0.rz-berlin.mpg.de/hjfdb/pdf/96e.pdf

Promoter action of alkali in the activation of CO2 on Pd(111): A HREELS case study

http://w0.rz-berlin.mpg.de/hjfdb/pdf/131e.pdf

D. Ehrlich

Papers

Hydroxyl groups on oxide surfaces: NiO(100), NiO(111) and Cr2O3(111)

Adsorption and Reaction on Oxide Surfaces: CO and CO2 on Cr2O3(111)

Structural rearrangement and surface magnetism on oxide surfaces: a temperature-dependent low-energy electron diffraction-electron energy loss spectroscopy study of Cr2O3(111)/Cr(110)

Promoter action of alkali in the activation of CO2 on Pd(111): A HREELS case study

Adsorption and reaction of molecules on surfaces of metal-metal oxide systems