Abstract

TiO₂–ZrO₂ mixed oxides with different amounts of TiO₂ were prepared by co-precipitation method and used to synthesize 1-octadecene from 1-octadecanol. The results show that the doping of TiO₂ leads to the formation of Lewis acid sites and Brønsted acid sites on the TiO₂–ZrO₂ mixed oxides. For catalysts with TiO₂ doping < 3 wt.%, the catalysts are in an intermediate state from the monoclinic and tetragonal zirconia crystalline phases to the amorphous form, and no Ti–O–Zr bond is formed. For catalysts with TiO₂ doping ≥ 3 wt.%, an amorphous structure and Ti–O–Zr bond are formed. The crystalline phase of metal oxides, amount and type of acid sites simultaneously affect the performance of the catalysts. The acid sites on TiO₂–ZrO₂ mixed oxides with monoclinic and tetragonal zirconia crystalline phases have much lower dehydration activity than those with an amorphous form. Lewis acid sites are responsible for both the dehydration of 1-octadecanol to form 1-octadecene and the double carbon bond migration of 1-octadecene to form 2-octadecene. Brønsted acid sites mainly catalyze the double carbon bond migration of 1-octadecene.

Graphic abstract

中文翻译：

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晶相和酸位对TiO 2 -ZrO 2复合氧化物上1-十八醇脱水为1-十八烯的影响

摘要

采用共沉淀法制备了不同TiO ₂含量的TiO ₂ -ZrO ₂混合氧化物，并用于由1-十八醇合成1-十八碳烯。结果表明，TiO ₂的掺杂导致在TiO ₂ -ZrO ₂混合氧化物上形成路易斯酸位和布朗斯台德酸位。对于TiO ₂掺杂<3 wt。％的催化剂，该催化剂处于从单斜晶和四方晶氧化锆晶相到无定形形式的中间状态，并且没有形成Ti–O–Zr键。用于TiO ₂催化剂掺杂≥3 wt。％，形成非晶结构和Ti–O–Zr键。金属氧化物的结晶相，酸位点的数量和类型同时影响催化剂的性能。具有单斜晶和四方晶系氧化锆晶相的TiO ₂ -ZrO ₂混合氧化物上的酸点具有比无定形形式低得多的脱水活性。路易斯酸位点负责1-十八碳烯醇的脱水形成1-十八碳烯和1-十八碳烯的双碳键迁移形成2-十八碳烯。布朗斯台德酸位点主要催化1-十八碳烯的双碳键迁移。

图形摘要