Atomic force and scanning electron microscopic investigation of the in operandi creation of selective sites on MoO3 mixed with α-Sb2O4 in the isobutene to methacrolein oxidation

Oxyfunctionalization of Alkanes

“…It is remarkable to see that the feed change from alkane to olefin also results in a reduction of the hydrocarbon conversion of over two orders of magnitude! Results indicate that oxygen transfer into the uppermost surface layer can take place from over 10 to 15 unit cells within the bulk of the catalyst [134,135]. From these studies it becomes apparent that the transitionally occurring adsorbed olefinic intermediates in n-butane oxidation must either be present at very low concentrations, or be of a different nature compared to alkenes dosed via the feedstream.…”

Synergistic Effects between Acid and Base Sites and Kinetic for Synthesis of Methylacrolein on the Cs-P/γ-Al2O3 Catalyst

“…Methyl methacrylate (MMA) as a very important chemical feedstock is widely used in the field of optical elements, aviation units, optical fibers, optical mirrors, robots, and transistor fabrication. − Meanwhile, methylacrolein (MAL) is the key stock for synthesis of MMA through selective oxidation followed by esterification or direct oxidative esterification with methanol. − Until now, the approaches to MAL are mainly focused on selective oxidation of isobutene or isobutane − and sec -amine-catalyzed Mannich reactions between propanal and formaldehyde, − which are summarized in Scheme .…”

“…In addition, a new crystal phase of α-Bi 2 Mo 3 O 12 , which was the source of cooperation effects, would form when the reaction temperature exceeded 400 °C. Under the optimal condition, the conversion and selectivity could reach up to 90 and 87%. , Except for these published papers, a lot of international patents have been applied and granted in the research area of Mo–Bi catalysts, and the conversion and selectivity changes from 95.4 to 99.5% and 83.3 to 97.1%, respectively, at the temperatures of 300–365 °C. − Also, further experimental studies in combination with theoretical calculation revealed the cooperation interaction existing among the composite oxides, which significantly affects the conversion and selectivity, and the catalytic sites formed through an oxygen spillover. − In addition to Mo–Bi catalysts, other bicomponent oxides and noble metal-supported catalysts are reported. Liu synthesized a series of Re–Sb–O compounds, which were active for oxidation of isobutylene to MAL with 83% selectivity at 350–450 °C, but the conversion was only 15% .…”

Probing the reduction state of Mo oxide catalysts by the deoxygenation of carboxylic acid

“…It progressively becomes well accepted that a key to optimize the performances of Mo oxide catalysts in selective oxidation processes is to stabilize them in a slightly reduced state during the reaction [1][2][3][4]. Now, a crucial aspect to be understood in order to further improve performances of such processes is to identify the optimal reduction state of the catalysts in terms of location and of concentration of the reduced features.…”

“…The bulk and the surface can equilibrate their coordination and structure with the composition (i.e. the reduction/oxidation strength) of the reaction gas and the temperature, eventually resulting in reconstruction phenomena [2,3]. In situ characterization (with the catalysts maintained in reaction conditions during the characterization) and operando characterization (an in situ characterization coupled to a simultaneous measurement of the catalytic performances) are efficient approaches to handle such a delicate behavior.…”