Preparation of Er2O3 Nanorod Catalyst without Using Organic Additive and Its Application to Catalytic Dehydration of 1,4-Butanediol

Abstract

Er 2 O 3 nanorods were successfully prepared with hydrothermal treatment without using organic additives such as surfactant, fatty acid, or alcohol. Er 2 O 3 nanorods were obtained under high temperature and/or long reaction times. Er 2 O 3 nanorods mainly exposed {440} and {400} facets on the surface. Er 2 O 3 nanorods showed excellent catalytic activity compared to commercial Er 2 O 3 nanoparticles in the dehydration of 1,4-butanediol to produce 3-buten-1-ol. 9 Other REO nanorods are also prepared with organic additives. 10 There is only one report on CeO 2 nanorods prepared without organic substance but with sodium hydroxide.2 Unfortunately, organic additives and residual metal cations often work as catalytic poison. It is desired that oxide catalysts are prepared without organic additives and metal-containing bases.In our previous work, 11 1,4-butanediol was dehydrated to 3-buten-1-ol with selectivity higher than 90% over commercial Er 2 O 3 nanoparticles, and it was speculated that active sites of this reaction exist on {222} facet. Much more data, however, are required to discuss active crystal facets on the catalysis. The purpose of this work is to prepare Er 2 O 3 nanorods without organic additives and to investigate catalytic activity of Er 2 O 3 nanorods in order to ascertain whether the active sites exist on {440} and {400} facets.Commercial Er 2 O 3 nanoparticles, supplied by Kanto Chemical Co., Ltd., Japan, were calcined at 500, 650, 800, and 1000°C, which have specific surface areas of 33.5, 26.8, 21.5, and 13.6 m 2 g ¹1 , respectively. Er 2 O 3 nanoparticle or nanorod catalyst was prepared with a HT method. Er(NO 3 ) 3 ¢5H 2 O (4.64 g, as 2.0 g of Er 2 O 3 , Sigma-Aldrich, USA) was dissolved in 50mL of distilled water. Then, the pH of the solution was adjusted to 10 with 25 wt % aqueous ammonia (Wako, Japan) with stirring. No additives such as amine, fatty acid, or alcohol were added. The solution was transferred into a 100-cm 3 Teflon-lined autoclave. Hydrothermal treatment was carried out at a prescribed temperature for a prescribed period. The resulting precipitate was filtered, washed, dried at 110°C for 12 h, and calcined at 400°C for 3 h. Here, commercial Er 2 O 3 is named as "CM-(calcination temperature (°C))," and the prepared Er 2 O 3 is named as "HT-(HT temperature (°C))-(HT time (h))."Specific surface area (SA) of the sample was calculated by the BrunauerEmmettTeller (BET) method using the N 2 adsorption isotherm at ¹196°C. Scanning electron microscope (SEM) and high-resolution transmission electron microscope (TEM) images were taken on a JEOL JSM-6510 microscope operated at 2030 kV and on a Hitachi HF-2200 microscope operated at 200 kV, respectively.Vapor-phase catalytic dehydration of 1,4-butanediol to produce 3-buten-1-ol was performed at 350°C in a fixed-bed down-flow reactor under atmospheric pressure of N 2 at a flow rate of 30 cm 3 min ¹1 . After 0.3 g of catalyst was preheated at 400°C for 1 h, 1,4-butanediol was fed into the reactor at a liquid flow rate of 1.8 cm 3 min ¹1 . A ...

Selective Dehydration of Alkanediols into Unsaturated Alcohols over Rare Earth Oxide Catalysts

“…We have successfully prepared Er 2 O 3 nanorods using an aqueous ammonia solution as a precipitation reagent without organic additives, such as surfactant, fatty acid, or alcohol . The Er 2 O 3 nanorods are obtained at an appropriate pH under hydrothermal conditions at temperatures higher than 100 °C, for long reaction times, or both.…”

“…High-resolution TEM image of Er 2 O 3 nanorods prepared under hydrothermal conditions at 200 °C for 24h. Republished with permission from ref .…”

“…Dehydration of 1,4-butanediol over Er 2 O 3 catalysts with (solid circle, numbers indicate hydrothermal temperature and duration) nanorods and (open triangle, number indicates calcination temperature) nanoparticles. Republished with permission from ref .…”

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