Impact of cationic lanthanum species on zeolite Y: an infrared, excess infrared and Raman spectroscopic study

Abstract

The recently proposed technique of excess infrared spectroscopy was extended for the first time to a solid system to explore the host-guest interactions between the framework of zeolite Y and the encapsulated lanthanum species. By employing infrared, excess infrared and Raman spectroscopies, the physical insights into the band shifts/intensity variations of asymmetric TO 4 (T ¼ Si, Al) stretching and T-O-T bending were revealed. In the ion-exchange process, the ring distortions were sensitively distinguished by the red shift of the T-O-T bending bands. Upon dehydration, the strengthening effect on the T-O bond was demonstrated by the absorption of the interaction pair between the zeolite framework and dehydrated lanthanum species ([La(OH) n ] (3Àn)+ (n ¼ 1, 2) and La 3+ ), revealing the mechanism of the stabilization effect of lanthanum species on the zeolite framework. Also, the Raman band located at 362 cm À1 was found to be directly related to the 6-membered rings in the hexagonal prisms of zeolite Y. Moreover, Raman spectroscopy showed the capability to describe the distinction between rare earth oxides within and outside the microporous zeolites. XPS, 27 Al and 29 Si MAS NMR were also performed for further validations.

A green method to increase yield and quality of bio-oil: ultrasonic pretreatment of biomass and catalytic upgrading of bio-oil over metal (Cu, Fe and/or Zn)/γ-Al2O3

“…[12][13][14] For instance, the acidic components in the bio-oil could lead to the corrosion of reactor and make the oil unstable. [12][13][14] For instance, the acidic components in the bio-oil could lead to the corrosion of reactor and make the oil unstable.…”

Halogen-bond and hydrogen-bond interactions between three benzene derivatives and dimethyl sulphoxide

“…In order to get rid of the overlap in the C-H stretching vibration region of C 6 F 5 H/ C 6 F 4 ClH and DMSO, deuterated dimethyl sulphoxide (DMSO-d 6 ) was used in the FTIR study. In particular, excess infrared spectroscopy [30][31][32][33][34][35][36][37][38][39] and two-dimensional correlation spectroscopy (2D-COS) 40,41 have been employed to reveal details of the molecular interactions.…”

Stability evaluation of ethanol dry reforming on Lanthania‐doped cobalt‐based catalysts for hydrogen‐rich syngas generation

“…Both catalysts possessed typical Co 3 O 4 bands at Raman shift of about 187.95, 468.55, 511.94, 608.36, and 673.93 cm −1 . The presence of Co 3 O 4 phase on catalyst surface was due to Co (NO 3 ) 2 decomposition and subsequent oxidation during air‐calcination at 773 K. The Raman peaks related to La 2 O 3 phase (viz, 280, 342, and 446 cm −1 ) were not detected on La‐promoted catalyst. It could be attributed to the formation of small La 2 O 3 crystallite size with low Raman reflection.…”