Carbon monoxide adsorption/desorption processes over NaX zeolite and supported ruthenium catalyst

Journal Article · Sat Oct 01 04:00:00 EDT 1988 · Journal of Catalysis; (USA)

DOI:https://doi.org/10.1016/0021-9517(88)90267-9· OSTI ID:6854946

Kamble, V S; Gupta, N M; Iyer, R M ^[1]

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1. Bhabha Atomic Research Centre, Bombay (India)

The binding states of CO on NaX zeolite and RuNaX were investigated by thermal desorption spectroscopy. Desorption peaks centered at around 390, 430, 490, and 520 K were observed from NaX following room-temperature adsorption of CO. The activation energy values corresponding to these peaks were calculated to be 41.4, 45.7, 53.8, and 57.7 kJ mol{sup {minus}1}, respectively. These peaks were also observed in desorption profiles from RuNaX although their temperatures were higher by 10 to 20 K. In addition, the desorption spectra from RuNaX also comprise two high-temperature peaks at around 575 and 640 K. With both the RuNaX and the NaX samples the temperature and relative intensities of the desorption peaks depended on pretreatment conditions and on the lapsed time between CO exposure to the sample and the commencement of programmed heating. Mass spectral analysis revealed that the gas desorbed at 300-500 K consisted mainly of CO while at higher temperatures CO{sub 2} was the main component. The desorption peaks below 500 K are attributed to the release of carbon monoxide from structural and intragranular or intergranular zeolitic pores. Lewis sites on the zeolite surface are found to facilitate activation of CO, resulting in its transformation to CO{sub 2}. The initial adsorption of carbon monoxide in zeolite pores and subsequent diffusion to metal sites leading to its disproportionation/oxidation is found to play an important role in the CO adsorption/desorption process on RuNaX.

• OSTI ID: 6854946
• Journal Information: Journal of Catalysis; (USA), Journal Name: Journal of Catalysis; (USA) Vol. 113:2; ISSN 0021-9517; ISSN JCTLA
• Country of Publication: United States
• Language: English

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