Alcohol Dehydration Reactions over Tungstated Zirconia Catalysts

Larsen, Gustavo; Lotero, Edgar; Petkovic, Lucı́a M.; Shobe, David S.

doi:10.1006/jcat.1997.1698

Cited by 75 publications

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“…Zirconia (or doped zirconia) dispersed in ceramics has long been applied to increase the fracture toughness, strength, and hardness [1 3]. A widely used catalyst and catalyst support, zirconia catalyzes alcohol dehydration [4,5], CO/CO 2 hydrogenation [6], alkane isomerization [7], selective oxidation of alcohols and alkanes [8,9], hydrogenation of olefins [10], and isomerization of olefi ns and epoxides [11,12]. Different zirconia phases (monoclinic and tetragonal) exhibit different catalyst selectivities, such as in the selective hydrogenation of CO and alkane isomerization reactions [13 15].…”

Section: Introductionmentioning

confidence: 99%

Fine tuning of the sizes and phases of ZrO2 nanocrystals

Wang

2009

Nano Res.

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Monodisperse and pure phase zirconia (tetragonal: T-ZrO 2 ; monoclinic: M-ZrO 2 ) nanocrystals with fi nely tuned sizes as well as ultrathin T-ZrO 2 nanowires have been selectively synthesized by a facile solvothermal method. For the fi rst time, a diagram of the size to effective strain was mapped for both T-ZrO 2 and M-ZrO 2 , which gives a good explanation for the size-and cation doping-dependent stability of the two phases on the sub-10 nm scale. This work may expand our understanding of the phase properties of not only zirconia, but also various other polymorphic nanocrystals.

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Section: Introductionmentioning

confidence: 99%

Fine tuning of the sizes and phases of ZrO2 nanocrystals

Wang

2009

Nano Res.

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“…Three crystal structures of ZrO 2 , tetragonal, monoclinic and cubic phases have been reported. 39,40 However, in the case of ZrO 2 modified with MoO 3 , the crystalline structures of the samples were different from that of pure ZrO 2 . For the 5-MoO 3 /ZrO 2 , as shown in Figure 5, X-ray diffraction data indicated tetragonal ZrO 2 form at 400-600 o C, and a two-phase mixture of the tetragonal and monoclinic ZrO 2 forms at 700-900 o C. It is assumed that the interaction between molybdenum oxide and ZrO 2 hinders the transition of ZrO 2 from amorphous to tetragonal phase.…”

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confidence: 95%

Spectroscopic Studies on ZrO₂Modified with MoO₃and Activity for Acid Catalysis

2003

Bulletin of the Korean Chemical Society

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Zirconia modified with MoO 3 was prepared by impregnation of powdered Zr(OH) 4 with ammonium heptamolybdate aqueous solution followed by calcining in air at high temperature. Spectroscopic studies on prepared catalysts were performed by using FTIR, Raman, XRD, and DSC and by measuring surface area. Upon the addition of molybdenum oxide to zirconia up to 15 wt%, the specific surface area increased in proportion to the molybdate oxide content, while acidity measured by irreversible chemisorption of ammonia exhibited a maximum value at 3 wt% of MoO 3 . Since the ZrO 2 stabilizes the molybdenum oxide species, for the samples equal to or less than 30 wt%, molybdenum oxide was well dispersed on the surface of zirconia and no phase of crystalline MoO 3 was observed at any calcination temperature above 400 o C. The catalytic activities for cumene dealkylation were roughly correlated with the acidity of catalysts measured by ammonia chemisorption method, while the catalytic activities for 2-propanol dehydration were not correlated with the acidity because weak acid sites are necessary for the reaction.

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“…Current dehydration methods use strong acids, such as sulfuric acid or p-toluenesulfonic acid (pTSA), [1] or solid acids, such as zeolites [2] or metal oxides. [3,4] The major problems with these methods are their low selectivity and low functional group tolerance. Therefore a selective, widely useable dehydration method is highly desirable.…”

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Catalytic Dehydration of Benzylic Alcohols to Styrenes by Rhenium Complexes

2010

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The catalytic dehydration of (poly)alcohols represents a facile route to (functionalized) olefins. Current dehydration methods use strong acids, such as sulfuric acid or p-toluenesulfonic acid (pTSA), [1] or solid acids, such as zeolites [2] or metal oxides. [3,4] The major problems with these methods are their low selectivity and low functional group tolerance. Therefore a selective, widely useable dehydration method is highly desirable. Such a method might prove useful in the dehydration of biomassbased compounds, which are very rich in hydroxyl groups. Dehydration of both the (hemi)cellulosic components of biomass as well as aromatic lignin components could provide very interesting building blocks for the chemical industry. [5,6] To date only a few alcohol-to-olefin dehydration reactions catalyzed by homogeneous catalysts have been reported. Catalysts based on ruthenium [7,8] have proven active in the combined dehydration/hydrogenation of diols, and also palladium- [9] and zinc-based [10] catalysts have been reported for the dehydration of alcohols. A remarkable non-metal-based dehydration of glycerol and erythritol that makes use of formic acid was recently reported by Ellman et al. [11] High-valent rhenium complexes have also shown promising activity in dehydration reactions. Multiple methods were reported: Methyltrioxorhenium(VII) (MTO; CH 3 ReO 3 ) showed good results at room temperature in the dehydration of various alcohols, [12] while in the presence of hydrogen at higher temperature and pressure epoxides were deoxygenated in good and diols in moderate yield.[13] Cp*ReO 3 performed very well in the presence of PPh 3 in the deoxygenation of various diols and polyols, [14] however, phosphine oxide was obtained as a byproduct in quantitative amounts. Herein, we report on a study into various rhenium-based catalysts for the dehydration of alcohols to olefins under mild conditions. We initially focused on the dehydration of various benzylic alcohols.Following the original procedure by Zhu and Espenson, [12] the first attempts using MTO as a catalyst for the dehydration of 1,2,3,4-tetrahydronaphthol 1 to 1,2-dihydronaphthalene 2 (Scheme 1) at room temperature gave surprisingly poor results. The yield of 2 using benzene as a solvent was only 4 %, while 71 % was originally reported. In our hands, the highest yield of 2 obtained was 10 %, using THF as solvent, a reaction time of 3 days, and 10 mol % MTO as catalyst at room temperature. Using the same procedure at elevated temperature, however, gave very good results. In toluene at 100 8C, complete conversion was obtained after as little as 30 min reaction time, yielding olefin 2 as the single product. Lowering the amount of catalyst to 1 mol % also resulted in complete conversion after 30 min. Next, different commercially available rhenium complexes were tested for their activity in reaction 1. A blank reaction gave low conversion after 3 days of reaction time, yielding a mixture of both olefin and ether. Re 2 (CO) 10 did show some activity, yet poor selectivity...

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Alcohol Dehydration Reactions over Tungstated Zirconia Catalysts

Cited by 75 publications

References 0 publications

Fine tuning of the sizes and phases of ZrO2 nanocrystals

Fine tuning of the sizes and phases of ZrO2 nanocrystals

Spectroscopic Studies on ZrO₂Modified with MoO₃and Activity for Acid Catalysis

Catalytic Dehydration of Benzylic Alcohols to Styrenes by Rhenium Complexes

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Alcohol Dehydration Reactions over Tungstated Zirconia Catalysts

Cited by 75 publications

References 0 publications

Fine tuning of the sizes and phases of ZrO2 nanocrystals

Fine tuning of the sizes and phases of ZrO2 nanocrystals

Spectroscopic Studies on ZrO2Modified with MoO3and Activity for Acid Catalysis

Catalytic Dehydration of Benzylic Alcohols to Styrenes by Rhenium Complexes

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Spectroscopic Studies on ZrO₂Modified with MoO₃and Activity for Acid Catalysis