Vapor-phase catalytic dehydration of butanediols to unsaturated alcohols over yttria-stabilized zirconia catalysts

• Published in: Applied catalysis. A, General General, 2019-04, Vol.575, p.48-57
• Main Authors: Ohtsuka, Shota, Nemoto, Takuma, Yotsumoto, Rikako, Yamada, Yasuhiro, Sato, Fumiya, Takahashi, Ryoji, Sato, Satoshi
• Format: Article
• Language: English
• Subjects: Butanediols; Dehydration; Tetragonal phase; Unsaturated alcohols; Yttria-stabilized zirconia
• ISSN: 0926-860X; 1873-3875
• DOI: 10.1016/j.apcata.2019.02.013

[Display omitted] •Vapor-phase dehydration of butanediols was studied over Y-stabilized ZrO2 catalysts with tetragonal phase.•Unsaturated alcohols were preferentially produced in the dehydration of 1,3-butanediol over Y-stabilized ZrO2.•Catalytic activity was greatly enhanced by calcination temperature of Y-stabilized ZrO2 catalysts.•Stable 1,3-butanediol conversion with high unsaturated alcohols selectivity of 96.9% was obtained at 325 oC.•Catalytic activity was sensitively dependent upon the flow rate of nitrogen carrier gas. Vapor-phase catalytic dehydration of butanediols (BDOs) such as 1,3-, 1,4-, and 2,3-butanediol was investigated over yttria-stabilized tetragonal zirconia (YSZ) catalysts as well as monoclinic zirconia (MZ). BDOs were converted to unsaturated alcohols with some by-products over YSZ and MZ. YSZ is superior to MZ for these reactions in a view point of selective formation of unsaturated alcohols. Calcination temperature of YSZ significantly affected the products selectivity as well as the conversion of BDOs: high selectivity to unsaturated alcohols was obtained over the YSZ calcined at high temperatures over 800 °C. In the conversion of 1,4-butanediol at 325 °C, the highest 3-buten-1-ol selectivity of 75.3% was obtained over the YSZ calcined at 1050 °C, whereas 2,3-butanediol was less reactive than the other BDOs. In the dehydration of 1,3-butanediol at 325 °C, in particular, it was found that a YSZ catalyst with a Y2O3 content of 3.2 wt.% exhibited an excellent stable catalytic activity: the highest selectivity to unsaturated alcohols such as 2-buten-1-ol and 3-buten-2-ol over 98% was obtained at a conversion of 66%. Structures of active sites for the dehydration of 1,3-butanediol were discussed using a crystal model of tetragonal ZrO2 and a probable model structure of active site was proposed. The well-crystalized YSZ inevitably has oxygen defect sites on the most stable surface of tetragonal ZrO2 (101). The defect site, which exposes three cations such as Zr4+ and Y3+, is surrounded by six O2− anions. The selective dehydration of 1,3-butanediol to produce 3-buten-2-ol over the YSZ could be explained by tridentate interactions followed by sequential dehydration: the position-2 hydrogen is firstly abstracted by a basic O2− anion and then the position-1 hydroxyl group is subsequently or simultaneously abstracted by an acidic Y3+ cation. Another OH group at position 3 plays an important role of anchoring 1,3-butanediol to the catalyst s