Sonochemical synthesis of nanostructured catalysts

Conference · Fri Dec 01 04:00:00 EST 1995

OSTI ID:126775

Suslick, K S; Cichowlas, A A; Fang, Ming Ming; Hyson, T ^[1]

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1. Univ. of Illinois, Urbana-Champaign, IL (United States)

We have discovered a sonochemical route to a general synthesis of nanostructured materials. Ultrasonic irradiation of liquids creates acoustic cavitation: the formation, growth, and implosive collapse of bubbles in a liquid, which produces intense local heating ({approx}5000 K), high pressures ({approx}1700 atm), and enormous heating and cooling rates (> 10{sup 9} K/sec). These unusual conditions can form amorphous manometer clusters of metals, metal oxides, or metal carbides from the sonolysis of volatile organometallic precursors (e.g., Fe(CO){sub 5}, Co(CO){sub 3}(NO), Mo(CO){sub 6}, W(CO){sub 6}). We have prepared nanostructured powders, polymer- stabilized colloids, and silica-supported heterogeneous catalysts of metals, alloys, oxides, and carbides. Typical particle sizes in all cases are {approx}5 nm, and the particles are amorphous at the manometer scale from XRPD, TEM microdiffraction, and neutron diffraction studies. We have examined the catalytic activity of these materials using a gas-solid flow microreactor with GC/MS detection. The sonochemically prepared Fe, Co, and Fe-Co powders are extremely active catalysts for dehydrogenation and hydrogenolysis of alkanes and the alloys show exceptionally high selectivity for dehydrogenation. In the case of Mo(CO){sub 6}, nanophase cubic molybdenum semicarbide, Mo{sub 2}C, is produced sonochemically. The nanophase Mo{sub 2}C is an active and selective heterogeneous catalyst for alkane dehydrogenation.

• OSTI ID: 126775
• Report Number(s): CONF-950402--
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
40 CHEMISTRY
ALKANES
ALLOYS
CATALYSTS
CATALYTIC EFFECTS
COBALT
COLLOIDS
DEHYDROGENATION
HETEROGENEOUS CATALYSIS
IRON
IRRADIATION
MOLYBDENUM CARBIDES
NEUTRON DIFFRACTION
ORGANOMETALLIC COMPOUNDS
SILICA
SOUND WAVES
SYNTHESIS