Mesoporous Co‐Al oxide nanosheets as highly efficient catalysts for CO oxidation

Abstract

We report mesoporous Co‐Al oxide nanosheets (CoxAl‐Ns, where x denotes the Co/Al ratio in the samples) prepared by calcination of CoAl‐hydrotalcite and subsequent alkaline treatment. X‐ray diffraction, scanning electron microscopy, transmission electron microscopy, and X‐ray photoelectron spectroscopy measurements show that the prepared Co‐Al oxide nanosheets (CoxAl‐Ns) are very thin (10–15 nm) and exhibit high mesoporosity (3–5 nm). Catalytic CO oxidation tests reveal that the CoxAl‐Ns exhibit excellent catalytic performances at relatively low temperatures: for example, the Co2.5Al‐Ns catalyst could achieve 99% CO conversion at −98°C. Kinetic studies and experimental investigations indicate that the high activity of the Co2.5Al‐Ns sample is strongly related to the abundance of active sites associated with the large Brunauer–Emmett–Teller surface area. The Co2.5Al‐Ns catalyst also achieves full conversion of CO in tests performed with a gas mixture simulating automobile exhaust gas at 200°C. After loading the Co2.5Al‐Ns on a porous ceramic substrate, the obtained Co2.5Al‐Ns/PC shows high activity and stability in CO oxidation process. These features are potentially important for future industrial applications of these catalysts.

Boosting primary amines renewable tandem synthesis via defect engineering of NiCo alloy

“…37 While the Ni 0 peak of NiCo/NiCoAlO x -2 sample shifted to higher energy compared with the NiCo/NiCoAlO x -5 (0.4 eV) and NiCo/NiCoAlO x -10 (0.6 eV) catalyst. 38,39 The above results reflected with NH 3 to form 7a, and the 7a is easy to condensate with AMF to form intermediates 3a due to the intensely reactive and unstable properties. The 3a not only could convert to AMF by ammonolysis but also react with the highly reactive 7a to further form 5-hydroxymethylfurfuramide (5a) and 6a.…”

Overcoming limitations in propanedehydrogenation by codesigning catalyst-membrane systems

“…This goal can be accomplished by using hollow-fiber membranes with small diameters packed with a PDH catalyst inside the hollow-fiber membrane. These hollow-fiber geometries allow for high membrane surface areas per volume of reactor (>1000 m 2 /m 3 ), which can decrease overall reactor volumes to achieve desired conversions (21,29).…”

“…One obstacle is the limited availability of selective H 2 -transporting membranes that can operate under these conditions. Previous studies have attempted to use metal-based (palladium) (16,(18)(19)(20), zeolite (20)(21)(22), and oxide-based membranes (16,18,23,24) with very limited success owing to high cost, chemical reactivity that results in low product selectivity, and susceptibility to deactivation by carbon deposition (coking) under PDH conditions (15,18). In addition, commercial PDH catalysts are not viable for these systems because they are designed to operate with extra H 2 added to the reactant stream.…”

Ordered macro-mesoporous nanostructure of Pd/ZrO2 catalyst for boosting catalytic soot oxidation

“…13,14 The ordered mesoporous materials possess high surface area and large pore volume, which offer abundant space to disperse reaction sites for adsorbing and activating gaseous reactants. [15][16][17][18] The metal active sites can oxidize gas reactants to intermediate NO 2 with strongger oxidation ability, which results in converting reaction mechanism from gas (O 2 )-solid (catalyst)-solid (soot) to solid (catalyst)-gas (NO 2 )-solid (soot) style. 19 Thus, the ordered mesoporous nanostructure is potential to enhance contact efficiency between catalyst and gas reactants indirectly by change of reaction pathway.…”