Methanol synthesis over Cu/SiO2 catalysts

Robbins, John L.; Iglesia, Enrique; Kelkar, C. P.; DeRites, Bruce A.

doi:10.1007/bf00764730

Cited by 53 publications

(77 citation statements)

References 32 publications

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“…However, SiO 2 provides a good model system because it is widely regarded as unreducible under synthesis conditions. Although Cu/SiO 2 is not used commercially for synthesis of methanol, the observed rate of CO/CO 2 hydrogenation to CH 3 OH with this catalyst, expressed per Cu-site, was within a factor of three of the rates reported by others over Cu/ZnO and Cu/ZnO/Al 2 O 3 catalysts under comparable conditions [6].…”

Section: Introductionsupporting

confidence: 71%

“…A Cu/SiO 2 catalyst (2.1 wt.% Cu) was prepared by urea-assisted decomposition of aqueous copper nitrate onto Davison 62 silica, as described in reference [6]. The Cu dispersion measured by N 2 O frontal chromatography was 18% [6].…”

Section: Methodsmentioning

confidence: 99%

“…The Cu dispersion measured by N 2 O frontal chromatography was 18% [6]. A pre-reduced and passivated sample (0.3 g) was pressed into a 1 in diameter wafer at 35 MPa and the wafer was mounted in an in-situ XAS cell designed and built by Lytle [30].…”

Section: Methodsmentioning

confidence: 99%

“…Recent studies agree that CO 2 rather than CO is the direct precursor to CH 3 OH on Cu-containing catalysts, based on the initial appearance of 13 CH 3 OH from CO/ 13 CO 2 /H 2 mixtures [6], on infrared spectra of adsorbed intermediates [7,8], and on transient kinetic studies [9]. It has even been reported that methanol synthesis from mixtures of H 2 and CO does not occur on Cu/SiO 2 [10].…”

Section: Introductionmentioning

confidence: 90%

“…This same catalyst was used in a previous study to establish the role of metallic Cu in methanol synthesis [6]. Silica supports have not been as extensively studied as ZnO, Al 2 O 3 , or ZrO 2 in methanol synthesis catalysts.…”

Section: Introductionmentioning

confidence: 99%

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New insights into methanol synthesis catalysts from X-ray absorption spectroscopy

Meitzner¹,

Iglesia

1999

Catalysis Today

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X-ray absorption spectroscopic studies from several different groups provide a consistent structural picture of methanol synthesis catalysts. Copper metal is the principal Cu species detected in all in-situ XAS studies. A small amount of Cu(II) persisted in many samples reduced below 600 K, but it appears to be catalytically irrelevant. Cu(I) was not detected in any of the in-situ XAS studies. The Zn structure did not change in response to chemical treatments in any of the ZnO-containing methanol synthesis catalysts.We conclude that the slow approach to steady-state rate of methanol synthesis from CO/H 2 mixtures cannot result from changes in the Cu metal component of Cu/SiO 2 catalysts. By eliminating this possibility, we provide indirect evidence for the proposal that initial induction periods reflect slow changes in the surface of the SiO 2 or ZnO component in the catalysts. A bifunctional mechanism involving the formation of formate from CO on support hydroxyl groups would increase methanol synthesis rates as OH groups are formed by hydrolysis of Si-O bonds using the H 2 O formed in slow methanation side reactions. The bifunctional mechanism is not required for the synthesis of methanol from CO 2 -containing mixtures, because formate can form on Cu directly from CO 2 and H 2 .

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Section: Introductionsupporting

confidence: 71%

Section: Methodsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 90%

Section: Introductionmentioning

confidence: 99%

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New insights into methanol synthesis catalysts from X-ray absorption spectroscopy

Meitzner¹,

Iglesia

1999

Catalysis Today

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Hydrogen Production and Synthesis Gas Reactions

Bartholomew

Farrauto²

2005

Fundamentals of Industrial Catalytic Processes

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Understanding the Origin of Structure Sensitivity in Nano Crystalline Mixed Cu/Mg−Al Oxides Catalyst for Low‐Pressure Methanol Synthesis

et al. 2021

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Cu nanoparticles of size 5-10 nm supported on MgÀ Al mixed oxide were prepared by the sol-gel method. Cu loading was varied from 2.5 to 10 wt % on the support to investigate the effect on particle size and activity/selectivity of the catalyst. The Cu/MgÀ Al catalysts containing small copper nanoparticles favor high selectivity of methanol, while the rate of CO formation was higher for larger copper particles. The high methanol selectivity (~99 %) and methanol formation rate (0.016 mol g Cu À 1 h À 1 ) over the 4.8Cu/MgÀ Al catalyst was due to the combined effect of the presence of high Cu dispersion, Cu surface area, and strong interaction between small Cu particles with MgÀ Al support. The high stability of the catalyst was attributed to the strong binding of the Cu cluster (À 179.7 kJ/mol) to the MgO/γ-Al 2 O 3 support, as shown by the DFT study. Additionally, the adsorption energy calculated using DFT showed preferential adsorption of CO 2 and H 2 at the Cu/MgO(100) active site (À 120.9 kJ/mol, À 130.4 kJ/mol) compared to the Cu/γ-Al 2 O 3 (100) (À 64.2 kJ/mol, À 85.7 kJ/mol)active site. The high selectivity of the catalyst towards methanol can be attributed to the higher stability of the formate (HCOO) intermediate (À 257.2 kJ/mol) compared to the carboxylate (COOH) intermediate (À 131.0 kJ/mol).

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Methanol synthesis over Cu/SiO2 catalysts

Cited by 53 publications

References 32 publications

New insights into methanol synthesis catalysts from X-ray absorption spectroscopy

New insights into methanol synthesis catalysts from X-ray absorption spectroscopy

Hydrogen Production and Synthesis Gas Reactions

Understanding the Origin of Structure Sensitivity in Nano Crystalline Mixed Cu/Mg−Al Oxides Catalyst for Low‐Pressure Methanol Synthesis

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