A study of catalytic activity, constituent, and structure of V-Ag catalyst for selective oxidation of toluene to benzaldehyde

Journal Article · Sat Jun 01 04:00:00 EDT 1991 · Journal of Catalysis; (USA)

DOI:https://doi.org/10.1016/0021-9517(91)90046-7· OSTI ID:5537962

Hui-Liang, Zhang; Wei, Zhong; Xiang, Duan; Xian-Cai, Fu ^[1]

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1. Nanjing Univ. (China)

A series of V-Ag mixed oxide catalysts with various atomic ratios of V and Ag were prepared by a solution-mixing method. XRD, TEM, SMEA (surface micro-area element analysis), ESR, FT-IR, etc., were used to study the physicochemical properties of the catalysts. The experimental results showed that when silver was introduced into the vanadium pentoxide, the V{double bond}O bond was weakened, and the specific activity of the sample increased. When the atomic ratios of V/Ag were set between 3/1 and 1/1, the selectivity for benzaldehyde increased. In particular, when the V/Ag ratio equaled 2.16, the selectivity for benzaldehyde was greatest, the absorption peak of 900 cm{sup {minus}1} in FT-IR shifted to lower energy, and the relative quantity of V{sup 4 {minus}} measured with ESR appeared the highest. After reaction, XRD showed the main phases of the catalyst to exist as Ag{sub 0{center dot}80}V{sub 2}O{sub 5}, and Ag{sub 0{center dot}68}V{sub 2}O{sub 5}, with a minor Ag phase. Small amounts of VO{sub 2} and V{sub 2}O{sub 4} were also detected. On the two component oxides of vanadium-silver, the toluene oxidation appeared to proceed through two parallel reaction paths: side-chain oxidation of toluene and oxidation coupling. The sample of pure silver promoted cleavage of the carbon ring of toluene and produced deep-oxidation products in large quantity, while the sample of pure V{sub 2}O{sub 5} promoted the oxidative coupling of toluene. After the addition of silver to V{sub 2}O{sub 5}, however the oxidative coupling reaction was depressed, and the silver-vanadium oxide phases, Ag{sub 0{center dot}80}V{sub 2}O{sub 5} and Ag{sub 0{center dot}68}V{sub 2}O{sub 5} were formed. These two phases are responsible for the selective oxidation of toluene.

• OSTI ID: 5537962
• Journal Information: Journal of Catalysis; (USA), Journal Name: Journal of Catalysis; (USA) Vol. 129:2; ISSN 0021-9517; ISSN JCTLA
• Country of Publication: United States
• Language: English

Related Subjects

02 PETROLEUM
020400* -- Petroleum-- Processing
ABSORPTION SPECTROSCOPY
ALDEHYDES
ALKYLATED AROMATICS
AROMATICS
BENZALDEHYDE
CATALYTIC EFFECTS
CATALYTIC REFORMING
CHALCOGENIDES
CHEMICAL PREPARATION
CHEMICAL REACTION KINETICS
CHEMICAL REACTIONS
COHERENT SCATTERING
DIFFRACTION
ELECTRON MICROSCOPY
ELECTRON SPIN RESONANCE
FOURIER TRANSFORMATION
HYDROCARBONS
INFRARED SPECTRA
INTEGRAL TRANSFORMATIONS
KINETICS
MAGNETIC RESONANCE
MICROANALYSIS
MICROSCOPY
ORGANIC COMPOUNDS
OXIDATION
OXIDES
OXYGEN COMPOUNDS
PHASE STUDIES
QUANTITY RATIO
REACTION KINETICS
REFORMER PROCESSES
RESONANCE
SCATTERING
SILVER COMPOUNDS
SILVER OXIDES
SPECTRA
SPECTROSCOPY
SYNTHESIS
TOLUENE
TRANSFORMATIONS
TRANSITION ELEMENT COMPOUNDS
TRANSMISSION ELECTRON MICROSCOPY
VANADIUM COMPOUNDS
VANADIUM OXIDES
X-RAY DIFFRACTION