Self- regeneration of Au/CeO2 based catalysts with enhanced activity and ultra-stability for acetylene hydrochlorination

Abstract

Replacement of Hg with non-toxic Au based catalysts for industrial hydrochlorination of acetylene to vinyl chloride is urgently required. However Au catalysts suffer from progressive deactivation caused by auto-reduction of Au(I) and Au(III) active sites and irreversible aggregation of Au(0) inactive sites. Here we show from synchrotron X-ray absorption, STEM imaging and DFT modelling that the availability of ceria(110) surface renders Au(0)/Au(I) as active pairs. Thus, Au(0) is directly involved in the catalysis. Owing to the strong mediating properties of Ce(IV)/Ce(III) with one electron complementary redox coupling reactions, the ceria promotion to Au catalysts gives enhanced activity and stability. Total pre-reduction of Au species to inactive Au nanoparticles of Au/CeO2&AC when placed in a C2H2/HCl stream can also rapidly rejuvenate. This is dramatically achieved by re-dispersing the Au particles to Au(0) atoms and oxidising to Au(I) entities, whereas Au/AC does not recover from the deactivation.

Facile synthesis of Au embedded CuOx-CeO2 core/shell nanospheres as highly reactive and sinter-resistant catalysts for catalytic hydrogenation of p-nitrophenol

“…After the hightemperature calcination, only 70.5% Au(0) can be preserved for Au@CeO2_700 CSNs, indicating the frangible oxidation of Au@CeO2 CSNs. The above results further demonstrated the efficient protective effect of CuOx-CeO2 nanospheres on the entrapped Au NPs, and thus resulted in the improved resistance to sintering [55].…”

Designing a 0D/2D S‐Scheme Heterojunction over Polymeric Carbon Nitride for Visible‐Light Photocatalytic Inactivation of Bacteria

“…As expected, a large number of tiny CeO 2 particles are uniformly dispersed on the surface of the PCN nanosheets (Figure b). The high‐resolution TEM (HRTEM) image (inset, Figure b) shows that the measured lattice fringe space of CeO 2 NPs is 0.316 nm, which is assigned to its (111) plane . High‐angle annular dark field transmission electron microscopic (HAADF‐TEM) images confirm that these tiny CeO 2 nanocrystallines are homogeneously anchored on the PCN nanosheets (Figure c,d; Supporting Information, Figure S3).…”

A colorimetric sensing platform based on self-assembled 3D porous CeGONR nanozymes for label-free visual detection of organophosphate pesticides

“…36 Ce(III) was partly oxidized in situ, then co-deposited on GONRs and formed nanoceria. 33 The NPs function not only as another efficient catalytic center, but also as a ''glue'' connecting the GONRs through a process of 1D to 3D self-assembly (Fig. 1A).…”