Cation Ordering in Natural and Synthetic (Cu1–xZnx)2CO3(OH)2 and (Cu1–xZnx)5(CO3)2(OH)6

Klokishner, Sophia; Behrens, Malte; Reu, Oleg S.; Tzolova-Müller, Genka; Girgsdies, Frank; Trunschke, Annette; Schlögl, Robert

doi:10.1021/jp205848s

Cited by 20 publications

(14 citation statements)

References 24 publications

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“…The geometries of Zn substituted malachite precursors (Cu 1‐ x Zn x ) 2 (OH) 2 CO 3 have been studied using first‐principles calculations based on DFT methods and experimental approaches . Based on first‐principles calculations, our previous work identified the ground structures and electronic properties of Zn substituted malachite suggesting that the (Cu 6/8 Zn 2/8 ) 2 (OH) 2 CO 3 precursor exhibits the most stable structure which is in good agreement with experimental data .…”

Section: Introductionsupporting

confidence: 62%

New Theoretical Insights into the Origin of Highly‐Effective Dispersion of Cu‐Based Catalysts As‐Synthesized Using Mg/Zn Doped Malachite as Precursors

Zheng

Narkhede

2019

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The effect of Mg substitution into malachite and Zn doped malachite structure has been precisely modeled and theoretically investigated for energetic, geometrical and electronic properties based on density functional theory. The calculations were carried out by well‐tested code Cambridge Serial Total Energy Package while the Local Density Approximation was applied to describe the exchange‐correlation potential. The Mg substitution added to the structural stability owing to its smallest formation energy and the stability of ‐Cu‐O−Mg‐ bond provides well dispersed Cu species. In addition, Mg offers higher tendency to form more stable structure with Cu than Zn at high substitution ratio of Mg/Cu. The introduction of Mg further increases the net charges of Zn atoms and reduces the covalent characteristic of Zn−O bond. The densities of states supported the strengthening of covalent characteristic of Zn−O and Cu−O while Mg−O exhibited ionic characteristic with increasing Mg/Zn. Our calculations provide fundamental understanding of Cu/Mg/Zn system resulting in effective Cu dispersion and thermodynamically stable activity.

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Section: Introductionsupporting

confidence: 62%

New Theoretical Insights into the Origin of Highly‐Effective Dispersion of Cu‐Based Catalysts As‐Synthesized Using Mg/Zn Doped Malachite as Precursors

Zheng

Narkhede

2019

ChemistrySelect

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“…Ageing critically affects the micro‐structural and consequently the catalytic properties of the resulting Cu/ZnO catalyst 31. The crystallization is associated with a change in color from blue to bluish green32 and, as expected, a change in particle size and morphology 33. The phase composition of the ageing product is mostly determined by the Cu:Zn ratio25a,34 but also by the mode of precipitation,35 and the speed of addition of the precipitating agent 34.…”

Section: The Chemistry Of Precipitate Ageingmentioning

confidence: 84%

How to Prepare a Good Cu/ZnO Catalyst or the Role of Solid State Chemistry for the Synthesis of Nanostructured Catalysts

Behrens

Schlögl

2013

Zeitschrift anorg allge chemie

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155

151

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In this research report we summarize recent progress that has been made in the field of Cu/ZnO catalyst synthesis. We briefly introduce the fields of application of this catalyst: methanol synthesis, the water gas shift reaction, and methanol steam reforming. The review is focused on the well‐documented industrial synthesis protocol and on the early stages of catalyst synthesis. The setting of the most critical synthesis parameters during co‐precipitation and ageing, like pH and temperature, is discussed in detail. We show how these parameters effect the phase formation and identify zincian malachite, (Cu, Zn)2(OH)2CO3, as the relevant precursor phase for high‐performance catalysts. A special emphasis is placed on the solid state chemistry of this precursor phase, in particular on the structural effects of Cu, Zn substitution. Based on the structural analysis, it is shown that the industrial synthesis recipe was empirically optimized to maximize the zinc incorporation into zincian malachite. From this insight a simple and generic geometric concept for the synthesis of nanostructured composite catalysts based on de‐mixing of solid solution precursors is derived. With this concept, the complex multi‐step industrial synthesis can be rationalized and the so‐called “chemical memory” of this catalyst synthesis can be understood. We also demonstrate how application of this concept can lead to new interesting catalytic materials, which help to address fundamental questions of this catalyst system like to role of the Al2O3 promoter or the so‐called Cu‐Zn synergy.

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“…The change of the position of the broad signal from 505 to 515 nm reflects a change in crystal field splitting around the Cu 2+ ions and the transition from blue to bluish green. 35 Difference plots of the normalized in situ recorded spectra are shown in Fig. 5b.…”

Section: Phase Evolutionmentioning

confidence: 99%

In situ EDXRD study of the chemistry of aging of co-precipitated mixed Cu,Zn hydroxycarbonates – consequences for the preparation of Cu/ZnO catalysts

2012

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In order to better understand the critical influence of the synthesis parameters during preparation of Cu/ZnO catalysts at the early stages of preparation, the aging process of mixed Cu,Zn hydroxide carbonate precursors was decoupled from the precipitation and studied independently under different conditions, i.e. variations in pH, temperature and additives, using in situ energy-dispersive XRD and in situ UV-Vis spectroscopy. Crystalline zincian malachite, the relevant precursor phase for industrial catalysts, was formed from the amorphous starting material in all experiments under controlled conditions by aging in solutions of similar composition to the mother liquor. The efficient incorporation of Zn into zincian malachite can be seen as the key to Cu/ZnO catalyst synthesis. Two pathways were observed: direct co-condensation of Cu(2+) and Zn(2+) into Zn-rich malachite at 5 ≥ pH ≥ 6.5, or simultaneous initial crystallization of Cu-rich malachite and a transient Zn-storage phase. This intermediate re-dissolved and allowed for enrichment of Zn into malachite at pH ≥ 7 at later stages of solid formation. The former mechanism generally yielded a higher Zn-incorporation. On the basis of these results, the effects of synthesis parameters like temperature and acidity are discussed and their effects on the final Cu/ZnO catalyst can be rationalized.

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Cation Ordering in Natural and Synthetic (Cu_1–xZn_x)₂CO₃(OH)₂ and (Cu_1–xZn_x)₅(CO₃)₂(OH)₆

Cited by 20 publications

References 24 publications

New Theoretical Insights into the Origin of Highly‐Effective Dispersion of Cu‐Based Catalysts As‐Synthesized Using Mg/Zn Doped Malachite as Precursors

New Theoretical Insights into the Origin of Highly‐Effective Dispersion of Cu‐Based Catalysts As‐Synthesized Using Mg/Zn Doped Malachite as Precursors

How to Prepare a Good Cu/ZnO Catalyst or the Role of Solid State Chemistry for the Synthesis of Nanostructured Catalysts

In situ EDXRD study of the chemistry of aging of co-precipitated mixed Cu,Zn hydroxycarbonates – consequences for the preparation of Cu/ZnO catalysts

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