TY - JOUR
T1 - Studies of the mechanism of thiophene hydrodesulfurization
T2 - 2H NMR and mass spectral analysis of 1,3-butadiene produced in the deuterodesulfurization (DDS) of thiophene over PbMo6S8 catalyst
AU - Benson, John William
AU - Schrader, G. L.
AU - Angelici, Robert J.
N1 - Funding Information:
We appreciate the help of Chia-Mei Jen-Wang for building the flow reactor and of Jan Beane of the Iowa State University Mass Spectrometry laboratory for performing the deuterium analyses. We also thank Dr. Mark Ekman and Felix Koo for synthesizing the catalyst. This work was conducted at the Ames Laboratory, which is operated for the US Department of Energy by Iowa State University under Contract No. W-7405Eng-82. This research was supported by the Office of Basic Energy Sciences, Chemical Sciences Division.
PY - 1995/3/8
Y1 - 1995/3/8
N2 - The deuterodesulfurization (DDS) of thiophene was investigated over PbMo6S8 at 400°C using a flow-microreactor. Evidence indicates that 1,3-butadiene (BDE) is the first desulfurized product; its deuterium content was established by 2H NMR and mass spectrometries. At different levels of thiophene conversion (0.86-10.2%), the amount of deuterium incorporated into BDE remains constant at 3.47 D atoms per BDE molecule. Unconverted thiophene incorporates 0.42 D atoms at 10.2% thiophene conversion but only 0.05 D atoms at 0.86% conversion. Reaction of 2,5-dihydrothiophene (2,5-DHT) with D2 at 400°C over PbMo6S8 liberates BDE as the only hydrocarbon product. This BDE incorporates no deuterium. Thiophene and H2S effectively inhibit both BDE hydrogenation and deuterium exchange. The results indicate that during the DDS process, a total of 3.2 deuterium atoms are incorporated into the BDE; 0.83 D are in the DA-position while 1.2 D are in each of the DB-and DC-positions. Several HDS mechanisms proposed in the literature are consistent with these results; two are not. Details of all of these mechanisms are discussed.
AB - The deuterodesulfurization (DDS) of thiophene was investigated over PbMo6S8 at 400°C using a flow-microreactor. Evidence indicates that 1,3-butadiene (BDE) is the first desulfurized product; its deuterium content was established by 2H NMR and mass spectrometries. At different levels of thiophene conversion (0.86-10.2%), the amount of deuterium incorporated into BDE remains constant at 3.47 D atoms per BDE molecule. Unconverted thiophene incorporates 0.42 D atoms at 10.2% thiophene conversion but only 0.05 D atoms at 0.86% conversion. Reaction of 2,5-dihydrothiophene (2,5-DHT) with D2 at 400°C over PbMo6S8 liberates BDE as the only hydrocarbon product. This BDE incorporates no deuterium. Thiophene and H2S effectively inhibit both BDE hydrogenation and deuterium exchange. The results indicate that during the DDS process, a total of 3.2 deuterium atoms are incorporated into the BDE; 0.83 D are in the DA-position while 1.2 D are in each of the DB-and DC-positions. Several HDS mechanisms proposed in the literature are consistent with these results; two are not. Details of all of these mechanisms are discussed.
KW - Chevrel phase catalyst
KW - Deuterium labelling
KW - Hydrodesulphurization
KW - Mechanisms
KW - Thiophene
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U2 - 10.1016/1381-1169(94)00025-5
DO - 10.1016/1381-1169(94)00025-5
M3 - Article
AN - SCOPUS:0000016042
SN - 1381-1169
VL - 96
SP - 283
EP - 299
JO - Journal of Molecular Catalysis. A, Chemical
JF - Journal of Molecular Catalysis. A, Chemical
IS - 3
ER -