Characterization of Activated Carbon Using X-ray Photoelectron Spectroscopy and Inelastic Neutron Scattering Spectroscopy

Abstract

The surface chemistry of a commercial activated carbon (Sutcliffe DCL 230), which is representative of carbons used as support materials in finely divided metal catalysts, has been characterized by a combination of traditional methods (surface area, porosity, Boehm titration, adsorption studies) supplemented by X-ray photoelectron spectroscopy (XPS) and inelastic neutron scattering (INS) spectroscopy. pH measurements show the carbon to be highly acidic, with Boehm titration and XPS suggesting a high proportion of carboxylic and lactonic surface groups. Adsorption of phenylacetylene and benzonitrile was followed by UV-vis spectroscopy to determine the affinity of the carbon for substituted aromatics. INS was carried out on the as-received material and also after the adsorption of pyridine on the carbon surface, which was used as a probe of surface acidity. Pyridine chemisorption yielded an excellent INS spectrum, which closely matched solid pyridine, indicating a relatively weak interaction between the carbon and the pyridine. The INS spectrum also confirmed that the number of acid sites capable of protonating pyridine was below an upper limit of 5.6 × 10 19 (g of carbon) -1 . Collectively, this work emphasizes the amphoteric nature of the carbon studied, albeit with a strong acid bias, and indicates that bulk acidity is a poor description of the carbon's chemisorption characteristics.

Adsorption of Metal Ions on an Activated Carbon/L‐Lysine Derivative Hybrid Compound

“…In agreement with the TPD data, the latter band can be decomposed into three signals corresponding to the C=O groups of carbonyl and quinone functions (at 531.7 eV), oxygen atoms of lactone functions (at 533.9 eV) and chemisorbed water (at 537.1 eV; Figure 8 and Table 5). [25][26][27][28] Bearing in mind the small proton affinities of carbonyl and lactone functions, the basic character of the AC (pH pcz = 8.3) [9] is mainly due to processes of the type C π + H 3 …”

Polymers of Intrinsic Microporosity (PIMs): Bridging the Void between Microporous and Polymeric Materials

“…Futhermore, the surface of activated carbons is chemically ill-defined with a large variety of oxygen-and nitrogen-containing functional groups present, in addition to the polycyclic aromatic units that form the graphene sheets. [18][19][20][21] The heterogeneous structure and chemical nature of the exposed surface area explains the ability of activated carbons to adsorb a wide range of organic compounds and metal ions, but limits its potential for chemo-selective processes.…”

Diamond-Like Carbon Nanofoam from Low-Temperature Hydrothermal Carbonization of a Sucrose/Naphthalene Precursor Solution

“…XPS has been successfully applied to many different carbon materials [121] such as activated carbon [122], carbon spheres [123], amorphous carbon, nanodiamonds [124], diamond-like carbon films [125], carbon nanotubes [126], or nanoporous carbons [127]. Also, it can be used to study processes such as heat and chemical treatment [128], amorphization [129], electrochemical oxidation [130], or structural deformation [131].…”