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Title: Selective methane oxidation over promoted oxide catalyst. Quarterly report, September--November 1993

Abstract

Dispersed metal oxide catalysts have been prepared and tested for selective oxidation of methane. The catalysts were based on multivalent cations impregnated into a number of different oxide supports: MoO{sub 3}/SiO{sub 2}, V{sub 2}O{sub 5}/SiO{sub 2}, V{sub 2}O{sub 5}/MoO{sub 3}/SiO{sub 2}, V{sub 2}O{sub 5}/TiO{sub 2}, SnO{sub 2}/SiO{sub 2}, and V{sub 2}O{sub 5}/SnO{sub 2}. Among the dispersed metal oxide catalysts studied this quarter, the most active catalyst was clearly the V{sub 2}O{sub 5}/SiO{sub 2} catalyst. High surface area silica samples impregnated with 1--5 wt% V{sub 2}O{sub 5} were found to be active catalysts with low selectivity toward CO{sub 2}. Although CO was the major product, appreciable selectivities toward formaldehyde were also observed. Indeed, with the V{sub 2}O{sub 5}/SiO{sub 2} catalysts, very high space time yields of formaldehyde of > 1 kg CH{sub 2}O/kg catal/h could be obtained even though conventional single pass %yields were <2%. These results were obtained at relatively high GHSV (70,000--280,000 {ell}/kg catal/h) but moderate temperatures (530--630C).

Authors:
; ; ;
Publication Date:
Research Org.:
Lehigh Univ., Bethlehem, PA (United States). Dept. of Chemistry
Sponsoring Org.:
USDOE, Washington, DC (United States)
OSTI Identifier:
10134776
Report Number(s):
DOE/MC/29228-3670
ON: DE94004086; BR: AB0530150/AC0535000
DOE Contract Number:
FG21-92MC29228
Resource Type:
Technical Report
Resource Relation:
Other Information: PBD: Jan 1994
Country of Publication:
United States
Language:
English
Subject:
10 SYNTHETIC FUELS; 03 NATURAL GAS; METHANE; OXIDATION; FORMALDEHYDE; CHEMICAL REACTION YIELD; CATALYSTS; PROGRESS REPORT; VANADIUM OXIDES; SILICON OXIDES; MOLYBDENUM OXIDES; TITANIUM OXIDES; TIN OXIDES; MIXTURES; 100200; 034000; PRODUCTION; COMBUSTION

Citation Formats

Klier, K., Herman, R.G., Sarkany, J., and Sun, Q.. Selective methane oxidation over promoted oxide catalyst. Quarterly report, September--November 1993. United States: N. p., 1994. Web. doi:10.2172/10134776.
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Klier, K., Herman, R.G., Sarkany, J., & Sun, Q.. Selective methane oxidation over promoted oxide catalyst. Quarterly report, September--November 1993. United States. doi:10.2172/10134776.
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Klier, K., Herman, R.G., Sarkany, J., and Sun, Q.. Sat . "Selective methane oxidation over promoted oxide catalyst. Quarterly report, September--November 1993". United States. doi:10.2172/10134776. https://www.osti.gov/servlets/purl/10134776.
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@article{osti_10134776,
title = {Selective methane oxidation over promoted oxide catalyst. Quarterly report, September--November 1993},
author = {Klier, K. and Herman, R.G. and Sarkany, J. and Sun, Q.},
abstractNote = {Dispersed metal oxide catalysts have been prepared and tested for selective oxidation of methane. The catalysts were based on multivalent cations impregnated into a number of different oxide supports: MoO{sub 3}/SiO{sub 2}, V{sub 2}O{sub 5}/SiO{sub 2}, V{sub 2}O{sub 5}/MoO{sub 3}/SiO{sub 2}, V{sub 2}O{sub 5}/TiO{sub 2}, SnO{sub 2}/SiO{sub 2}, and V{sub 2}O{sub 5}/SnO{sub 2}. Among the dispersed metal oxide catalysts studied this quarter, the most active catalyst was clearly the V{sub 2}O{sub 5}/SiO{sub 2} catalyst. High surface area silica samples impregnated with 1--5 wt% V{sub 2}O{sub 5} were found to be active catalysts with low selectivity toward CO{sub 2}. Although CO was the major product, appreciable selectivities toward formaldehyde were also observed. Indeed, with the V{sub 2}O{sub 5}/SiO{sub 2} catalysts, very high space time yields of formaldehyde of > 1 kg CH{sub 2}O/kg catal/h could be obtained even though conventional single pass %yields were <2%. These results were obtained at relatively high GHSV (70,000--280,000 {ell}/kg catal/h) but moderate temperatures (530--630C).},
doi = {10.2172/10134776},
journal = {},
number = ,
volume = ,
place = {United States},
year = {Sat Jan 01 00:00:00 EST 1994},
month = {Sat Jan 01 00:00:00 EST 1994}
}
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Technical Report:
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DOI:  10.2172/10134776
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  • ; ; ; ...
    Experimental research in the direct conversion of methane to methanol using a double bed reactor and with gaseous steam as cofeed with the CH{sub 4}/air reactant mixture continued during this quarter in order to improve the methanol space time yield. Work was carried out along several pathways that included a stability test of the second bed catalyst 1%V{sub 2}O{sub 5}/SiO{sub 2} that yielded up to 100 g methanol/kg cat/hr and investigation of the effect of pressure on methanol yields. Redox dopants were put onto several metal oxide supports in an attempt to find better second bed catalysts. A catalyst thatmore » was reasonably selective towards oxygenates was obtained when SiO{sub 2} was used as the support and low quantities of Fe or Cu were utilized. Attempts were also made to incorporate alkali ions into the catalysts to improve the surface hydrolyzability. Experiments were carried out to examine the effect of pressure and temperature on the oxygenate productivity over a double-layered catalyst bed of 0.1 g 1 wt% SO{sub 4}{sup 2{minus}}/Sr/La{sub 2}O{sub 3} as the first bed and 0.1 g 1 wt% V{sub 2}O{sub 5}/SiO{sub 2} as the second bed without H{sub 2}O cofeed in a glass-lined tubular down-flow reactor at pressures of 0.1--3.2 MPa (14.7--460 psig), temperatures of 450--500 C, and with a reactant flow rate having a ratio of CH{sub 4}/air = 150/50 ml/min. Reaction products observed were methanol, formaldehyde, carbon dioxide, acetylene, ethylene, and ethane. The overall activity of the catalyst increased at low pressures and high temperature. However, testing at low temperature and high pressure was found to favor methanol production.« less

  • ; ;
    The objective of this research is the selective oxidation of methane to C{sub 2}H{sub 4} hydrocarbons and to oxygenates, in particular formaldehyde and methanol. Air, oxygen, or carbon dioxide rather than nitrous oxide, are utilized as the oxidizing gas at high gas hourly space velocity but mild reaction conditions (500-700{degrees}C, 1 atm total pressure). All the investigated processes are catalytic, aiming at minimizing gas phase reactions that are difficult to control. During this quarter, solid state {sup 51}V NMR and double catalyst bed experiments were conducted to demonstrate the unfavorable effect of the presence of bulk crystalline V{sub 2}O{sub 5}more » in V{sub 2}O{sub 5}-SiO{sub 2} xerogel catalysts on selective oxidation of methane to methanol and formaldehyde. Results are discussed.« less

  • ; ; ; ...
    Support effects on catalytic reactions, especially of highly exothermic oxidation reactions, can be very significant. Since we had shown that a MoO{sub 3}/SiO{sub 2} catalyst, especially when used in a double bed configuration with a Sr/La{sub 2}O{sub 3} catalyst, can selectively oxidize methane to formaldehyde, the role of the SiO{sub 2} support was investigated. Therefore, partial oxidation of methane by oxygen to form formaldehyde, carbon oxides, and C{sub 2} products (ethane and ethene) has been studied over silica catalyst supports (fumed Cabosil and Grace 636 silica gel) in the 630-780{degrees}C temperature range under ambient pressure. When relatively high gas hourlymore » space velocities (GHSV) were utilized, the silica catalysts exhibit high space time yields (at low conversions) for methane partial oxidation to formaldehyde, and the C{sub 2} hydrocarbons were found to be parallel products with formaldehyde. In general, the selectivities toward CO were high while those toward CO{sub 2} were low. Based on the present results obtained by a double catalyst bed experiment, the observations of product composition dependence on the variation of GHSV (i.e. gas residence time), and differences in apparent activation energies of formation of C{sub 2}H{sub 6}, and CH{sub 2}O, a reaction mechanism is proposed for the activation of methane over the silica surface. This mechanism can explain the observed product distribution patterns (specifically the parallel formation of formaldehyde and C{sub 2} hydrocarbons).« less

  • ; ; ; ...
    At 550{degree}C, the 1 wt % SO{sub 4}{sup 2}{minus}/l wt % Sr/La{sub 2}O{sub 3} catalyst, one of the most active catalyst for the selective conversion of methane at these moderate temperatures, showed a very good stability with a reactant mixture of CH{sub 4}/air = 1/1 with GHSV = 70,040 {ell}/kg catal/hr. During a 25 hr catalytic test, the conversion of CH{sub 4} and the C{sub 2}{sup +} selectivity did not change, indicating good stability of the catalyst. At the same time, the CO{sub 2}/CO ratio remained steady at about 2.2, but the C{sup 2}{sup =}/C{sub 2} ratio shifted slightly withmore » time from 0.74 to 0.68. The oxidative coupling of CH{sub 4} to C{sub 2}-hydrocarbons was very sensitive at 550{degree}C to the alteration of the CH{sub 4}/air reactant ratio at GHSV = 70,040 {ell}/kg catal/hr. It was observed that the conversion of CH{sub 4}, the C{sub 2}{sup +} selectivity, and the %yield of C{sub 2}{sup +} hydrocarbon products decreased very rapidly with increasing CH{sub 4}/air ratio from 1 to 3-4. At the largest CH{sub 4}/air ratio of 40.77 that was used utilized, the CH{sub 4} conversion was less than 0-5 C-mol%. The reverse process of decreasing the CH{sub 4}/air ratio from {approx}40 to 1 showed nearly reversible catalytic performance, but some deactivation was apparent at the lowest reactant ratios. The 1 wt % SO{sub 4}{sup 2}{minus}/1 wt % Sr/La{sub 2}O{sub 3} catalyst used in the experiments in which the CH{sub 4}/air ratio was varied subsequently revealed a good stability in the CH{sub 4} conversion level during testing at 550{degree}C for 15 hr (GHSV = 70,040 {ell}/kg catal/hr and CH{sub 4}/air = 1/1). Indeed, the C{sub 2}{sup +} selectivity even increased by 3 to 4 C-mol%. Increasing the temperature from 550 to 600{degree}C resulted in a further recovery of the activity of the partially deactivated catalyst.« less

  • ; ; ; ...
    A 1 wt% SO{sub 4}{sup 2{minus}}/1 wt% Sr/La{sub 2}O{sub 3} catalyst has been shown by us to be one of the most active catalyst for the oxidative coupling of CH{sub 4} to C{sub 2} hydrocarbons. One of the by-products is CO{sub 2} and this is a potential strong poison for the formation of C{sub 2}{sup +} products. Hence, various pretreatments of this catalyst were studied in terms of effect on the catalytic performance. Before the reaction was carried out at 500 or 550{degrees}C, the catalyst was pretreated in flowing air or He at 500, 700, or 800{degrees}C. Relative to themore » 500{degrees}C treatment, the pretreatment in air at 700{degrees}C only slightly decreased the C{sub 2}{sup +} selectivity while the CO{sub x} selectivity increased. This effect was larger when the pretreatment was carried out at 800{degrees}C. It was observed that the deactivation effect was slightly smaller when the pretreatments were carried out in He instead of air. For both air and He, the CH{sub 4}, conversion and the C{sub 2} %yield showed more or less parallel changes (small decreases) with increasing pretreatment temperature. After a standard pretreatment (air, 500{degrees}C, 1 hr), the reaction temperature was increased stepwise from 500 to 700{degrees}C and then lowered to 550 (or 500){degrees}C. It was observed that the catalytic performance showed deactivation towards the C{sub 2}{sup +} products. Decreasing stepwise the total flow rate (GHSV) of the reacting gas mixture (CH{sub 4}/air = 1/1) from 70,175 to 5,388 {ell}/kg catal/hr at a reaction temperature of 550{degrees}C caused large changes in both the activity and selectivity. After going back at 550{degrees}C to the original GHSV = 70,175 {ell}/kg catal/hr, the temperature was increased stepwise up to 600{degrees}C. Up to 580{degrees}C, the catalytic activity and selectivity did not change very much.« less