Hydroalkylation of benzene and ethylbenzene over metal-containing zeolite catalysts

Nature of the Polycarbonyl Species on Ru/ZrO2: Reassignment of Some Carbonyl Bands

“…Supported ruthenium catalysts provoke a steady interest because of their application in various reactions . Therefore, many researchers have studied CO interaction with supported ruthenium. − However, it seems that the biggest disagreement on the nature of the surface carbonyl species concerns ruthenium carbonyls. There is consensus neither in the number of CO ligands nor in the oxidation state of ruthenium in the carbonyl species.…”

“…Similar bands have also been observed with nonreduced samples. Most of the researchers − identified three groups of bands: (i) high-frequency (HF 1 ), in the region between 2156 and 2130 cm –1 ; (ii) bands between 2090 and 2055 cm –1 that are usually called HF 2 ; and (iii) bands at low-frequencies (LF) appearing between 2060 and 1980 cm –1 . In some cases bands at even lower frequencies have been detected. ,,,, …”

“…Then, tricarbonyls were claimed to correspond to the set of HF 1 and HF 2 bands . These ideas were adopted and developed by many researchers who supported dicarbonyl, − ,,,,,,,, tricarbonyl, ,,,,− ,,,,,,, or simply polycarbonyl ,,,,,,,,,,,− ,− structures. The species characterized by the set of the HF 1 and HF 2 bands are also called II type of carbonyls.…”

“…Note that the existence of the III type of carbonyls is not generally accepted. Alternative assignments of the HF 2 band are available: linear carbonyls of Ru 0 , or Ru n + , ,,, bridging carbonyls, or tricarbonyls…”