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Syntheses of unsaturated alcohols in the vaporphase catalytic dehydration of alkanediols over rare earth oxides are reviewed. CeO 2 effectively catalyzes the dehydration of 1,3-butanediol to produce 3-buten-2-ol and trans-2-buten-1ol. Heavy rare earth oxides such as Er 2 O 3 , Yb 2 O 3 , and Lu 2 O 3 selectively catalyze the dehydration of 1,4-butanediol to produce 3-buten-1-ol. In the dehydration of 1,5-pentanediol, Yb 2 O 3 , Lu 2 O 3 , and Sc 0.5 Yb 1.5 O 3 catalysts efficiently work to produce 4-penten-1-ol. The active and selective oxides are composed of large particles with well-crystallized fluorite or bixbyite structure. Small oxide particles with poor crystallinity decrease the selectivity to unsaturated alcohols because of their dehydrogenation ability. In the reactions of different alkanediols, the reactivity of alkanediol depends on the length between the OH groups as well as on the geometry of the catalyst surface, which is affected by the distance between rare earth cations. For example, over CeO 2 , the reactivity order of the alkanediols is 1,3-butanediol > 1,4-butanediol > 1,5-pentanediol > 1,6-hexanediol. Quantum calculations support a probable reaction mechanism: OH groups and the H of the position-2 methylene group of 1,3butanediol are interacted with the surface Ce 4+ to form a tridentate coordination, and the abstraction of the position-2 H by Ce 4+ is the initial step of 1,3-butanediol dehydration in the formation of unsaturated alcohols.

The basal plane of graphene has been known to be less reactive than the edges, but some studies observed vacancies in the basal plane after reaction with oxygen gas. Observation of these vacancies has typically been limited to nanometer-scale resolution using microscopic techniques. This work demonstrates the introduction and observation of subnanometer vacancies in the basal plane of graphene by heat treatment in a flow of oxygen gas at low temperature such as 533 K or lower. High-resolution transmission electron microscopy was used to directly observe vacancy structures, which were compared with image simulations. These proposed structures contain C═O, pyran-like ether, and lactone-like groups.

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