Hydrogen chemisorption and mobility on Ru/SiO{sub 2}, K/Ru/SiO{sub 2} and Ru-Ag/SiO{sub 2}

Conference · Tue Dec 31 04:00:00 EST 1996

OSTI ID:468023

Narayan, R L; Savargaonkar, N; Pruski, M; King, T S ^[1]

---

1. Ames Laboratory IA (United States)

Microcalorimetry and {sup 1}H NMR have been used to investigate hydrogen chemisorption on Ru/SiO{sub 2}, K/Ru/SiO{sub 2} and Ru-Ag/SiO{sub 2}. Adding small amounts of K or Ag to Ru/SiO{sub 2} significantly reduces the amounts of hydrogen adsorbed and eliminates intermediate ({approx}50 kJ/mole) as well as weakly bound states (<10 kJ/mole) observed at higher pressures on Ru/SiO{sub 2}. Initial heats of adsorption ({approx}90 kJ/mole) are not affected by the presence of K or Ag on Ru. These observations combined with earlier atomistic simulations with Ru-Ag suggest that defect-like sites play an important role in adsorption and desorption behavior of hydrogen on Ru/SiO{sub 2}. Similar initial heats of adsorption and invariance of the {sup 1}H NMR Knight shift on Ag or K addition imply that there is no electronic effect. Further, the mobility of hydrogen is also reduced in the presence of K promoter. The different theories of alkali promotion in the literature is discussed in the light of the observations made in this work. It is noted that the weakly bound, atomic hydrogen observed at higher pressures can play an important role in catalysis.

• OSTI ID: 468023
• Report Number(s): CONF-960652--
• Country of Publication: United States
• Language: English

Related Subjects

01 COAL, LIGNITE, AND PEAT
ADSORPTION
CATALYSTS
CATALYTIC EFFECTS
CHEMISORPTION
DESORPTION
FISCHER-TROPSCH SYNTHESIS
HYDROGEN
HYDROGEN 1
KNIGHT SHIFT
NMR SPECTRA
POTASSIUM
RUTHENIUM
SILICA
SILVER