Direct oxidation esterification of methacrolein with methanol: Oxygen vacancy promotion of Zr‐doped Au/CeO₂ nanorods

Abstract

A series of Zr-doped CeO 2 nanorods supported by Au nanoparticle catalysts with different morphologies were prepared for methyl methacrylate (MMA) synthesis via direct oxidation esterification of methacrolein (MAL) with methanol. Catalytic activities under mild conditions (0.3 MPa; 80 C) were evaluated in the kettle reactor. Different characterization methods, such as XRD, Raman, N 2 adsorption, ICP, TEM, SEM, XPS, and H 2 -TPR techniques, were applied to study the relationship between catalytic activity and structural characteristics, especially the form of Zr doped into the lattice of CeO 2 and the promotion mechanism of selective oxidation.The influence of Au supported on Ce 0.6 Zr 0.4 O 2 nanorods (Au/CZ-R) was also discussed. The results exhibited that the highest catalytic activity for the oxidative esterification with a MAL conversion of 99% and a MMA selectivity of 74% was achieved. The MMA synthesis performance correlated well with the surface oxygen vacancies, in particular for the active oxygen species around the Au particles. K E Y W O R D Sactive oxygen species, CeO 2 nanorods, MMA, oxidative esterification, selective oxidation

Kinetic Studies on Both Synthesis of Methacrolein Catalyzed by an Ionic Liquid and Catalyst Deactivation

“…Methacrolein (MAL) is a vital intermediate and widely used in the production of fine chemicals such as methyl methacrylate and methacrylic acid. − It is also used as a raw material to synthesize polymers, resins, and thermoplastics. The demand for MAL continues to increase with high profit margins and use value …”

Ionic liquid-mediated hexagonally porous ZnO nanocrystal-supported Au catalysts: highly stable materials for aldehyde oxidative esterification

“…The main by-product is the acetal from the condensation of 2 moles of methanol with 1 mole of MAL. 33,34 Au/ZnO-C6 presented low conversion of MAL at 39%, and the selectivity for MMA was only 52% after reaction for 2 h. In contrast, Au/…”

Experimental methods in chemical engineering: Raman spectroscopy

“…Eng. published 11 articles: six are directly related to catalysis, [27][28][29][30][31] three are in the area of combustion, [32] one combined Raman and EDS to identify a low melting lithium phosphate phase in lithium iron phosphate ingots, [33] and another applied confocal Raman to measure solute concentrations in a hanging droplet (mass transfer). [34] Raman spectrographs now record the whole spectral range (Raman shifts from 100 cm −1 to 4000 cm −1 ) at subsecond resolution and are applied to pulse experiments with isotopes, to measure reaction kinetics and spectroscopic characteristics.…”

“…Eng . published 11 articles: six are directly related to catalysis, [ 27–31 ] three are in the area of combustion, [ 32 ] one combined Raman and EDS to identify a low melting lithium phosphate phase in lithium iron phosphate ingots, [ 33 ] and another applied confocal Raman to measure solute concentrations in a hanging droplet (mass transfer). [ 34 ]…”