Dehydrogenation of Alcohols: Formaldehyde

Dai, Wei‐Lin; Ren, Liping

doi:10.1002/9783527610044.hetcat0165

Cited by 8 publications

(8 citation statements)

References 53 publications

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“…The ratio of rates of production of acetaldehyde to formaldehyde is about 300 at 500 K, decreasing to about 200 and 100 at 600 and 700 K, respectively. Overall, the simulated results here are reasonably consistent with the experimental observations of the lower production efficiency of formaldehyde ,,, compared to acetaldehyde − on Cu. A high temperature is needed to produce anhydrous formaldehyde on Cu; however, an upper bound of temperature should exist to avoid its further decomposition into CO and H 2 .…”

Section: Resultssupporting

confidence: 87%

“…Overall, the decreased production efficiency of formaldehyde ,,, compared to acetaldehyde − on Cu can be qualitatively understood by their reaction kinetics. The critical differences in C–H bond-breaking barriers between methoxy and the other alkoxides are much larger than errors in the calculations, which are typically <0.05 eV.…”

Section: Resultsmentioning

confidence: 99%

“…Aldehydes, especially formaldehyde (CH 2 O), with millions of tons produced per year, are key precursors to many important chemical compounds. Currently, formaldehyde is manufactured by oxidative dehydrogenation of methanol (CH 3 OH) using silver-based catalysts, with water as a byproduct: 2 CH 3 OH + O 2 → 2 CH 2 O + 2 H 2 O. − It is desirable to dehydrogenate methanol to formaldehyde in an anhydrous manner, CH 3 OH → CH 2 O + H 2 , that is, without production of water, at moderate temperatures over nonprecious metals, such as Cu or Ni, so that the high energy-cost process of formaldehyde/water separation can be eliminated, − with the H 2 byproduct being useful as a clean fuel. Copper catalyzes anhydrous acetaldehyde (CH 3 CHO) production from ethanol (CH 3 CH 2 OH) at around 200–300 °C, − while the production of formaldehyde from methanol requires either the addition of a promoter (preadsorption of oxygen or water) or extremely high reaction temperatures. ,,, Given that methanol and ethanol, which differ by only one carbon atom in the carbon skeleton, are the two simplest alcohols, it is important to explain the mechanisms responsible for their very different dehydrogenation behavior over Cu.…”

Section: Introductionmentioning

confidence: 99%

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A Comparative Ab Initio Study of Anhydrous Dehydrogenation of Linear-Chain Alcohols on Cu(110)

et al. 2018

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The catalytic behavior of Cu surfaces in the anhydrous production of aldehydes from alcohols, a process of industrial significance, is puzzling: the two simplest alcohols (methanol and ethanol) show dramatically different decomposition behavior on Cu. Here, we study the thermodynamic and kinetic processes involved in the anhydrous dehydrogenation of linear-chain alcohols including methanol, ethanol, 1-propanol, and 1-butanol on the Cu(110) surface using multiscale approaches. First, we obtain the adsorption structures and energies of the reaction intermediates, in which van der Waals (vdW) interactions play a crucial role. Then, we determine the kinetic barriers for the two dehydrogenation steps, namely, the O−H and the subsequent C−H bond-breaking on Cu. The reaction of methoxy-to-formaldehyde has a rather high-energy transition state, in contrast to that of alkoxide-to-aldehyde in the longer-chain systems. This difference qualitatively explains the lower production efficiency of formaldehyde on Cu. Finally, we simulate the production rates of aldehydes based on which we optimize reaction conditions and propose possible avenues for enhancing the production of anhydrous formaldehyde using Cu-based catalysts.

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Section: Resultssupporting

confidence: 87%

Section: Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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A Comparative Ab Initio Study of Anhydrous Dehydrogenation of Linear-Chain Alcohols on Cu(110)

et al. 2018

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“…Aldehydes are important precursors or reactants in the production of a large number of industrial chemicals, such as plastics, resins, explosives, and drugs. , The oxidative dehydrogenation of alcohols over noble-metal-based catalysts in the presence of O 2 is generally used for commercial catalytic processes, − which creates a significant energy cost because of the need to separate the water byproduct . Therefore, there is considerable interest in the development of catalytic non-oxidative alcohol dehydrogenation pathways in which, instead of water, valuable H 2 is produced.…”

Section: Introductionmentioning

confidence: 99%

Surface Structure Dependence of the Dry Dehydrogenation of Alcohols on Cu(111) and Cu(110)

Wang

Xiao-min²,

El-Soda

et al. 2017

J. Phys. Chem. C

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The non-oxidative dehydrogenation of alcohols is considered as an important method to produce aldehydes for the chemical industry and hydrogen gas. However, current industrial processes are oxidative, meaning that the aldehydes are formed along with water, which, in addition to being less energy efficient, poses separation problems. Herein the production of aldehydes from methanol and ethanol on clean and dry Cu(111) and Cu(110) surfaces was investigated in order to understand the catalytic anhydrous dehydrogenation of alcohols. Both ethanol and methanol preferentially react under ultrahigh vacuum conditions at surface defects to yield acetaldehyde and formaldehyde, respectively, in the absence of surface oxygen and water. The amount of alkoxide reaction intermediates measured by scanning tunneling microscopy, and aldehyde and hydrogen products detected by temperature programmed reaction, are increased by inducing more defects in the Cu substrates with Ar ion sputtering. This work also reveals that the Cu model surfaces are not poisoned by the reaction and exhibit 100% selectivity for alcohol dehydrogenation to aldehyde and hydrogen.

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“…All the parameters of the microkinetic model were performed as described in Section 3 of the Supplementary information. The steadystate numerical solutions to the microkinetic model were obtained assuming a 0.1% approach to equilibrium (95% CH 3 OH, 1% CH 2 O, 1% CO, and 3% H 2 ) at 823 K and 1 bar to achieve reasonable rates and simulate reactor operation under differential conditions [28].…”

Section: Microkinetic Modelingmentioning

confidence: 99%

Using microkinetic analysis to search for novel anhydrous formaldehyde production catalysts

Lausche

Peterson

et al. 2015

Surface Science

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a b s t r a c tDirect dehydrogenation of methanol to produce anhydrous formaldehyde is investigated using periodic density functional theory (DFT) and combining the microkinetic model to estimate rates and selectivities on stepped (211) surfaces under a desired reaction condition. Binding energies of reaction intermediates and transition state energies for each elementary reaction can be accurately scaled with CHO and OH binding energies as the only descriptors. Based on these two descriptors, a steady-state microkinetic model is constructed with a piecewise adsorbate-adsorbate interaction model that explicitly includes the effects of adsorbate coverage on the rates and selectivities as well as the volcano plots are obtained. Our results show that most of the stepped (211) puremetallic surfaces such as Au, Pt, Pd, Rh, Ru, Ni, Fe, and Co are located in a region of low activity and selectivity toward CH 2 O production due to higher rate for CH 2 O dehydrogenation than CH 2 O desorption. The selectivities toward CH 2 O production on Zn, Cu, and Ag surfaces are located on the boundary between the high and low selectivity regions. To find suitable catalysts for anhydrous CH 2 O production, a large number of A 3 B-type transition metal alloys are screened based on their predicted rates and selectivities, as well as their estimated stabilities and prices. We finally propose several promising candidates for the dehydrogenation of CH 3 OH.Published by Elsevier B.V.

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Dehydrogenation of Alcohols: Formaldehyde

Abstract: The sections in this article are Introduction Direct Dehydrogenation of Methanol to Formaldehyde Silver‐Containing Catalysts Copper‐Containing Catalysts Zinc‐Containing Catalysts Other Catalysts Industrial Applications

Cited by 8 publications

References 53 publications

A Comparative Ab Initio Study of Anhydrous Dehydrogenation of Linear-Chain Alcohols on Cu(110)

A Comparative Ab Initio Study of Anhydrous Dehydrogenation of Linear-Chain Alcohols on Cu(110)

Surface Structure Dependence of the Dry Dehydrogenation of Alcohols on Cu(111) and Cu(110)

Using microkinetic analysis to search for novel anhydrous formaldehyde production catalysts

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