TY - JOUR

T1 - FTIR study of unsupported molybdenum sulfide - In situ synthesis and surface properties characterization

AU - Tsyganenko, A. A.

AU - Can, F.

AU - Travert, A.

AU - Maugé, F.

PY - 2004/8/10

Y1 - 2004/8/10

N2 - Self-supporting molybdenum sulfide samples with high surface area were prepared by in situ thermal decomposition in vacuum of ammonium thiomolybdate. BET specific surface area of the resulting material has its highest values of about 120m2/g for samples treated in situ at 473K and decreases on further heating, while the composition of samples treated at 423-473K is close to MoS3, and after heating up to 573K corresponds to MoS2. FTIR spectra show that precursor decomposition is almost completed already after treatment at 423K, although the sample still contains admixed ammonium ions. After 473K most of contaminations are gone. Spectra of adsorbed NH 3, ND3, CO, SO2, CO2, COS and CH3SH adsorbed on samples pretreated at 423-473K are very close to those obtained for air-contacted MoS2 powder. However higher band intensities and the use of labeled compound enabled us to identify the bands of coordinately bonded NH3 molecules and to point to the existence of acidic sites capable to protonate ammonia. Molecularly adsorbed CH3SH could be distinguished from its dissociative form; this reveals the existence of acid-base pair sites on bulk molybdenum sulfide.

AB - Self-supporting molybdenum sulfide samples with high surface area were prepared by in situ thermal decomposition in vacuum of ammonium thiomolybdate. BET specific surface area of the resulting material has its highest values of about 120m2/g for samples treated in situ at 473K and decreases on further heating, while the composition of samples treated at 423-473K is close to MoS3, and after heating up to 573K corresponds to MoS2. FTIR spectra show that precursor decomposition is almost completed already after treatment at 423K, although the sample still contains admixed ammonium ions. After 473K most of contaminations are gone. Spectra of adsorbed NH 3, ND3, CO, SO2, CO2, COS and CH3SH adsorbed on samples pretreated at 423-473K are very close to those obtained for air-contacted MoS2 powder. However higher band intensities and the use of labeled compound enabled us to identify the bands of coordinately bonded NH3 molecules and to point to the existence of acidic sites capable to protonate ammonia. Molecularly adsorbed CH3SH could be distinguished from its dissociative form; this reveals the existence of acid-base pair sites on bulk molybdenum sulfide.

KW - Acidity

KW - Adsorption

KW - Ammonium tetrathiomolybdate

KW - Basicity

KW - Infrared spectroscopy

KW - MoS

KW - Surface sites

UR - http://www.scopus.com/inward/record.url?scp=2942582322&partnerID=8YFLogxK

U2 - 10.1016/j.apcata.2004.03.038

DO - 10.1016/j.apcata.2004.03.038

M3 - Article

AN - SCOPUS:2942582322

VL - 268

SP - 189

EP - 197

JO - Applied Catalysis A: General

JF - Applied Catalysis A: General

SN - 0926-860X

IS - 1-2

ER -