Structural identification of ZnxZryOz catalysts for Cascade aldolization and self-deoxygenation reactions

Baylon, Rebecca A. L.; Kovařík, Libor; Engelhard, Mark H.; Li, Houqian; Winkelman, Austin D.; Wang, Yong

doi:10.1016/j.apcatb.2018.04.051

Cited by 50 publications

(56 citation statements)

References 66 publications

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“…The crystalline structure of Zn x Zr y O z catalysts have already been rigorously determined and reported and will only be briefly discussed here . Figure shows the XRD patterns recorded between 2θ=10°–70° for the Zn x Zr y O z catalysts and the ZrO 2 material.…”

Section: Resultsmentioning

confidence: 91%

“…For direct conversion of oxygenates (i. e., ethanol, acetic acid and ketones feed mixtures) to olefins over Zn x Zr y O z catalysts, it was proposed that the mechanism involves cascade reactions including aldol condensation followed by decomposition . In this work, the high concentration of water in the reactor system is likely to favor in‐situ formation of Brønsted acid sites and can also modify the surface species interactions both of which could impact the reaction mechanism.…”

Section: Resultsmentioning

confidence: 99%

“…In this work, the high concentration of water in the reactor system is likely to favor in‐situ formation of Brønsted acid sites and can also modify the surface species interactions both of which could impact the reaction mechanism. For instance, the decomposition of MEK to acetone and ethane could be favored because of the presence of water . A space velocity study was thus conducted with Zn 1 Zr 10 O x catalyst to gain insights regarding the reaction pathway for the formation of olefins from aqueous MEK and under inert environment (i. e. N 2 atmosphere).…”

Section: Resultsmentioning

confidence: 99%

“…This was recently confirmed by a detailed study from Wang et al. who demonstrated ∼80 % olefins selectivity at ∼98 % conversion using a mixture of acetone+MEK as feedstock …”

Section: Introductionmentioning

confidence: 99%

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Single‐step Conversion of Methyl Ethyl Ketone to Olefins over Zn_xZr_yO_z Catalysts in Water

Dagle

Kovařík

et al. 2019

ChemCatChem

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In this study we investigated the conversion of aqueous methyl‐ethyl‐ketone (MEK) to olefin fuel precursors over ZnxZryOz mixed oxide catalysts. Experiments were carried out in water as MEK is intended to be produced from the dehydration of 2,3‐butanediol in fermentation broth which is highly diluted in water. We demonstrated that ZnxZryOz catalysts are highly effective for converting aqueous MEK to C4−C5 olefins. High selectivity to olefins equal to 85 % was reached at 92 % per pass conversion when under H2 atmosphere. Catalyst stability was demonstrated for 60 hours’ time on stream, highlighting the potential for upgrading 2,3‐butanediol contained in fermentation broth without the need for energy‐intensive water separation. Increased concentration of MEK in the aqueous feed results in increased activity towards olefin production. However, water inhibits catalyst deactivation from coking. A mechanistic investigation revealed the impact of the reaction environment (inert or reducing atmosphere) on the reaction pathways. In an inert environment, the mechanism involves consecutive aldol condensation of MEK and 3‐pentanone intermediate. Under reducing conditions two reaction pathways compete with each other as MEK hydrogenation to butenes occurs concurrently with the aldol condensation/decomposition.

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Section: Resultsmentioning

confidence: 91%

Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

“…This was recently confirmed by a detailed study from Wang et al. who demonstrated ∼80 % olefins selectivity at ∼98 % conversion using a mixture of acetone+MEK as feedstock …”

Section: Introductionmentioning

confidence: 99%

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Single‐step Conversion of Methyl Ethyl Ketone to Olefins over Zn_xZr_yO_z Catalysts in Water

Dagle

Kovařík

et al. 2019

ChemCatChem

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“…The main peaks at 24.2, 28.2, 31.4, 40.8, 45.0, 50.0 and 55.6 • are assigned to the monoclinic phase of ZrO 2 (m-ZrO 2 , JCPDS cards no. 37-1484) [38,39]. While the four peaks at 30.2, 35.2, 50.4 and 60.0 • belong to the tetragonal phase of ZrO 2 (t-ZrO 2 , JCPDS cards no.…”

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confidence: 99%

Effect of Zirconia Polymorph on Vapor-Phase Ketonization of Propionic Acid

Ding

Zhao

2019

Catalysts

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Vapor-phase ketonization of propionic acid derived from biomass was studied at 300-375 • C over ZrO 2 with different zirconia polymorph. The tetragonal ZrO 2 (t-ZrO 2 ) are more active than monoclinic ZrO 2 (m-ZrO 2 ). The results of characterizations from X-ray diffraction (XRD) and Raman suggest m-ZrO 2 and t-ZrO 2 are synthesized by the solvothermal method. NH 3 and CO 2 temperature-programmed desorption (NH 3 -TPD and CO 2 -TPD) measurements show that there were more medium-strength Lewis acid base sites with lower coordination exposed on m-ZrO 2 relative to t-ZrO 2 , increasing the adsorption strength of propionic acid. The in situ DRIFTS (Diffuse reflectance infrared Fourier transform spectroscopy) of adsorbed propionic acid under ketonization reaction reveal that as the most abundant surface intermediates, the monodentate propionates are more active than bidentate propionates. In comparison with m-ZrO 2 , the t-ZrO 2 surface favors monodentate adsorption over bidentate adsorption. Additionally, the adsorption strength of monodentate propionate is weaker on t-ZrO 2 . These differences in adsorption configuration and adsorption strength of propionic acid are affected by the zirconia structure. The higher surface concentration and weaker adsorption strength of monodentate propionates contribute to the higher ketonization rate in the steady state.Catalysts 2019, 9, 768 2 of 15 coordination of Ti 4+ cations exposed on the surface. Stubenrauch et al. studied the reaction of formic acid and acetic acid on CeO 2 (111) and (100) surface [24]. On both surfaces, CH 2 CO was produced through acetic acid dehydration near 600 K. However, acetone was detected only on the (111) surface during acetic acid decomposition at 600 K. This result is different from that obtained by Kim et al., since Ce 4+ cations of (111) surface possess one vacancy relative to the Ce 4+ cations in the bulk. Wang et al. carried out ketonization of carboxylic acid on anatase and rutile TiO 2 , monoclinic and tetragonal ZrO 2 at 503-533 K [25,26]. They showed that the reaction activity of acetic acid was higher over anatase TiO 2 than that over rutile TiO 2 , and attributed that to the more reactive monodentate acetate present on anatase TiO 2 , whereas unreactive bidentate acetate was present on rutile TiO 2 . The effect of different nanocrystals (nanocubes, nanorods and nanopolyhedra) of CeO 2 on acetic acid ketonization was studied by Snell et al. at 503 K in the condensed phase and at 623 K in the vapor phase [27]. They found that the crystal of CeO 2 was disrupted in the condensed phase with the formation of metal carboxylate, whereas the bulk structure was maintained during the vapor phase reaction. They suggested that the morphology of CeO 2 did not have a critical influence on the reaction activity in the condensed and vapor phase. Although some work has been done on the influence of the structure, no consensus has been reached. This may be due to the different reaction conditions (condensed phase and vapor phase) via the different reaction...

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Direct Catalytic Conversion of Ethanol to C₅₊ Ketones: Role of Pd–Zn Alloy on Catalytic Activity and Stability

et al. 2020

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Ethanol can be used as a platform molecule for synthesizing valuable chemicals and fuel precursors. Direct synthesis of C5+ ketones, building blocks for lubricants and hydrocarbon fuels, from ethanol was achieved over a stable Pd‐promoted ZnO‐ZrO2 catalyst. The sequence of reaction steps involved in the C5+ ketone formation from ethanol was determined. The key reaction steps were found to be the in situ generation of the acetone intermediate and the cross‐aldol condensation between the reaction intermediates acetaldehyde and acetone. The formation of a Pd–Zn alloy in situ was identified to be the critical factor in maintaining high yield to the C5+ ketones and the stability of the catalyst. A yield of >70 % to C5+ ketones was achieved over a 0.1 % Pd‐ZnO‐ZrO2 mixed oxide catalyst, and the catalyst was demonstrated to be stable beyond 2000 hours on stream without any catalyst deactivation.

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Structural identification of ZnxZryOz catalysts for Cascade aldolization and self-deoxygenation reactions

Cited by 50 publications

References 66 publications

Single‐step Conversion of Methyl Ethyl Ketone to Olefins over Zn_xZr_yO_z Catalysts in Water

Single‐step Conversion of Methyl Ethyl Ketone to Olefins over Zn_xZr_yO_z Catalysts in Water

Effect of Zirconia Polymorph on Vapor-Phase Ketonization of Propionic Acid

Direct Catalytic Conversion of Ethanol to C₅₊ Ketones: Role of Pd–Zn Alloy on Catalytic Activity and Stability

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Structural identification of ZnxZryOz catalysts for Cascade aldolization and self-deoxygenation reactions

Cited by 50 publications

References 66 publications

Single‐step Conversion of Methyl Ethyl Ketone to Olefins over ZnxZryOz Catalysts in Water

Single‐step Conversion of Methyl Ethyl Ketone to Olefins over ZnxZryOz Catalysts in Water

Effect of Zirconia Polymorph on Vapor-Phase Ketonization of Propionic Acid

Direct Catalytic Conversion of Ethanol to C5+ Ketones: Role of Pd–Zn Alloy on Catalytic Activity and Stability

Contact Info

Product

Resources

About

Single‐step Conversion of Methyl Ethyl Ketone to Olefins over Zn_xZr_yO_z Catalysts in Water

Single‐step Conversion of Methyl Ethyl Ketone to Olefins over Zn_xZr_yO_z Catalysts in Water

Direct Catalytic Conversion of Ethanol to C₅₊ Ketones: Role of Pd–Zn Alloy on Catalytic Activity and Stability