The relative activities of a low-surface crystalline and high-surface amorphous LaOCl, further denoted as S1 and S2, have been compared for the destructive adsorption of CCl 4 . It was found that the intrinsic activity of S2 is higher than that of S1. Both samples were characterized with X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), N 2 -physisorption, and Raman and infrared (IR) spectroscopy. IR was used in combination with CO 2 , CO, and methanol as probe molecules. The CO 2 experiments showed that different carbonate species are formed on both materials. For S1, a high surface concentration of bidentate carbonate species and a lower concentration of monodentate carbonate were observed. In the case of S2, bulk carbonates were present together with bridged carbonates. CO adsorption shows that S2 and S1 have very similar Lewis acid sites. However, methanol adsorption experiments showed that S2 had a higher number of stronger Lewis acid sites than S1 and that twofold coordinated methoxy species were more strongly bound than threefold coordinated methoxy species. Because of the analogy between methanol dissociation and the removal of the first chlorine atom in the destructive adsorption of CCl 4 , the sites enabling twofold coordination were likely to be the same Lewis acid sites actively involved in the destructive adsorption of CCl 4 . La 2 O 3 was less active than the two LaOCl materials, and therefore, the intrinsic activity of the catalyst increases as the strength of the Lewis acid sites increases. S2 contains more chlorine at the surface than S1, which is expressed by the higher number of sites enabling twofold coordination. Moreover, this explains the difference in destructive adsorption capacity for CCl 4 that was observed for the samples S1 and S2. Since LaCl 3 , being the most acidic phase, is not active for the destructive adsorption of CCl 4 , basic oxygen atoms, however, remain needed to stabilize the reaction intermediate CCl 3 as La-O-CCl 3 .

Activity experiments using GC analysis of reactor effluent have been combined with in situ IR spectroscopy to elucidate the reaction steps in the destructive adsorption of CHCl3, CH2Cl2, and CH3Cl over LaOCl. The IR results show that during reaction, LaOCl is covered with carbonate, formate, and methoxy groups. The relative amount of each of these surface intermediates depends on the Cl/H ratio of the reactant. The decomposition of the surface species leads to formation of the reaction products, and is influenced by the temperature and the relative amount of Cl present on the surface. The GC results show that the activity for the destructive adsorption of H‐containing chlorinated C1 compounds decreases with increasing hydrogen content of the reactant. The acquired insight into the mechanism of destructive adsorption is crucial to the design of new catalyst materials for the efficient conversion of chlorinated hydrocarbons into nonhazardous products or reusable chemicals.

Pass the parcel: Activity experiments show that LaCl3 supported on carbon nanofibers is a highly active, selective, and stable catalyst for the H–Cl exchange reaction between CCl4 and CH2Cl2 to form CHCl3 (see scheme) in the absence of either lattice or gas‐phase oxygen. Density functional calculations suggest that the reaction proceeds through the formation of weakly adsorbed Cl and H species which can be exchanged between the reactants.

Lanthanum oxide-based catalysts are active in the elimination of HCl from C 2 H 5 Cl, 1,2-C 2 H 4 Cl 2 and 1,1,2-C 2 H 3 Cl 3 leading to the formation of their respective chlorinated ethenes. An oxygen-rich catalytic surface may form CO, CO 2 and C 2 HCl as side products, whereas with chlorine-rich catalytic surfaces a stable product distribution is achieved with 100% selectivity towards the formation of ethenes, such as the valuable C 2 H 3 Cl intermediate.

Ohne O: Aktivitätsexperimente zeigen, dass auf Kohlenstoffnanofasern fixiertes LaCl3 als hochaktiver, selektiver und stabiler Katalysator für den H‐Cl‐Austausch zwischen CCl4 und CH2Cl2 unter Bildung von CHCl3 wirkt (siehe Schema), wobei weder Gitter‐ noch Gasphasensauerstoff vorhanden ist. DFT‐Rechnungen zufolge verläuft die Reaktion über die Bildung von schwach adsorbierten Cl‐ und H‐Spezies, die zwischen den Reaktanten ausgetauscht werden können.