Vapor-phase catalytic dehydration of butanediols to unsaturated alcohols over yttria-stabilized zirconia catalysts
Vapor-phase catalytic dehydration of butanediols to unsaturated alcohols over yttria-stabilized zirconia catalysts
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DOI：
10.1016/j.apcata.2019.02.013
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发表时间：
2019-04
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影响因子：
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通讯作者：
Shota Ohtsuka;Takuma Nemoto;Rikako Yotsumoto;Yasuhiro Yamada;F. Sato;Ryōji Takahashi;S. Sato
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文献类型：
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作者：
Shota Ohtsuka;Takuma Nemoto;Rikako Yotsumoto;Yasuhiro Yamada;F. Sato;Ryōji Takahashi;S. Sato
研究了使用氧化钇稳定的四方氧化锆 (YSZ) 和单斜氧化锆 (MZ) 催化剂对 1,3-、1,4- 和 2,3-丁二醇等丁二醇 (BDO) 进行气相催化脱水。 BDO 在 YSZ 和 MZ 上转化为不饱和醇，并产生一些副产物。从选择性形成不饱和醇的角度来看，YSZ 在这些反应中优于 MZ。 YSZ的煅烧温度显着影响产物的选择性以及BDO的转化率：与800℃以上高温煅烧的YSZ相比，对不饱和醇的选择性较高。在 325°C 下转化 1,4-丁二醇时，与 1050°C 下煅烧的 YSZ 相比，获得了 75.3% 的最高 3-丁烯-1-醇选择性，而 2,3-丁二醇的反应性低于其他 BDO。特别是在1,3-丁二醇在325℃下脱水时，发现Y2O3含量为3.2wt.%的YSZ催化剂表现出优异的稳定催化活性：在66%的转化率下获得了对不饱和醇如2-丁烯-1-醇和3-丁烯-2-醇的最高选择性，超过98%。利用四方ZrO2晶体模型讨论了1,3-丁二醇脱水活性位点的结构，并提出了可能的活性位点模型结构。结晶良好的YSZ不可避免地在四方ZrO2(101)最稳定的表面上存在氧缺陷位点。缺陷位点暴露了三种阳离子，例如 Zr4+ 和 Y3+，被六个 O2− 阴离子包围。 1,3-丁二醇在YSZ上选择性脱水生成3-丁烯-2-醇可以通过三齿相互作用随后顺序脱水来解释：2位氢首先被碱性O2−阴离子夺去，然后1位羟基随后或同时被酸性Y3+阳离子夺去。 3 位的另一个 OH 基团在将 1,3-丁二醇锚定到催化剂表面方面发挥着重要作用。因此，1,3-丁二醇的选择性脱水可以通过推测的碱-酸协同机制进行。
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 Y2O3content 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 ZrO2and 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 surface. Thus, the selective dehydration of 1,3-butanediol could proceed via the speculative base-acid-concerted mechanism.