Promoting mechanism of sulfur addition in catalytic dehydrogenation of isobutane over Mo/MgAl sub(2)O sub(4) catalysts

• Published in: Applied catalysis. A, General General, 2014-05, Vol.478, p.71-80
• Main Authors: Wang, Guowei, Sun, Nannan, Gao, Chuancheng, Zhu, Xiaolin, Sun, Yanan, Li, Chunyi, Shan, Honghong
• Format: Article
• Language: English
• Subjects: Carbon monoxide; Catalysis; Catalysts; Dehydrogenation; Formations; Molybdates; Molybdenum disulfide; Sulfur
• ISSN: 0926-860X; 1873-3875
• DOI: 10.1016/j.apcata.2014.03.025

Mo/MgAl sub(2)O sub(4) catalysts with sulfur addition were verified to exhibit excellent performance in catalytic dehydrogenation of isobutane, which could yield up to 56.3 wt% isobutene at 560 [degrees]C. Catalyst characterization and activity test results jointly revealed that MoS sub(2) formed during the induction period probably constituted the active phase for dehydrogenation. As to the formation of MoS sub(2), treatment with appropriate reducing gases (e.g., CO) was required. However, in the atmosphere of H sub(2), molybdate species were partially reduced to MoO sub(2), which inhibited the formation of MoS sub(2). Furthermore, Mo/MgAl sub(2)O sub(4) catalysts sulfided by H sub(2)S/N sub(2) exhibited a high initial activity, further confirming that MoS sub(2) species were indispensable to dehydrogenation reaction. Stability evaluation of the Mo/MgAl sub(2)O sub(4)-S catalyst indicated that the catalytic activity decreased slightly within six reaction-regeneration cycles. The irreversible deactivation probably resulted from the obvious sulfur loss. Therefore, appropriate measures to replenish sulfur should be carried out in future commercial application.