Effects of steam on toluene hydrogenation over a Ni catalyst

• Published in: Applied catalysis. A, General Vol. 590; p. 117374
• Main Authors: Atsumi, Ryosuke, Kobayashi, Keisuke, Xieli, Cui, Nanba, Tetsuya, Matsumoto, Hideyuki, Matsuda, Keigo, Tsujimura, Taku
• Format: Journal Article
• Language: English
• Published: Amsterdam Elsevier B.V 25.01.2020; Elsevier Science SA
• Subjects: Byproducts; Conversion; Cyclic compounds; Disproportionation; Gas chromatography; Hydrogen carrier; Hydrogenation; Isomerization; Low-grade hydrogen; Methylcyclohexane; Nickel catalyst; Partial pressure; Selectivity; Silicon dioxide; Toluene; Toluene hydrogenation; Nickel catalyst; Low-grade hydrogen; Toluene hydrogenation; Hydrogen carrier; Methylcyclohexane
• ISSN: 0926-860X; 1873-3875
• DOI: 10.1016/j.apcata.2019.117374

[Display omitted] •Toluene hydrogenation with steam-containing hydrogen (wet-H2) was conducted using an industrial Ni catalyst for H2 storage.•Methylcyclohexane selectivity increased with increasing steam partial pressure.•Wet-H2 produced in a water electrolysis system can be used directly in toluene hydrogenation. The catalytic toluene hydrogenation over Ni/SiO2 was carried out using H2 or a H2/H2O mixture. The toluene conversion and MCH selectivity were evaluated under partial steam pressures 0−10 kPa, at H2/toluene molar ratios 1–5, and at temperatures 393−453 K. In the absence of steam, toluene conversion increased with increasing H2 partial pressure, and the MCH selectivity decreased with increasing temperature. In the presence of steam, the toluene conversion showed near-constant activities over the entire range of steam partial pressures, and the MCH selectivity increased with increasing steam partial pressure. This result indicated that the addition of steam inhibited byproduct formation. To clarify the effects of steam on the side-reaction, the byproducts composition was analyzed using a gas chromatograph. The results showed that the addition of steam inhibited demethylation, the ring-opening reaction of MCH, the disproportionation of toluene, and isomerization to convert six-membered ring compounds into five-membered ring compounds.