Structural Effects of Cu/Zn Substitution in the Malachite–Rosasite System

Behrens, Malte; Girgsdies, Frank

doi:10.1002/zaac.201000028

Cited by 94 publications

(128 citation statements)

References 24 publications

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“…It can be seen in Fig. 2 that the lattice parameters evolve-similarly to the zincian malchite case 16 -anisotropically in a linear Vergard-type fashion in the range 0 r x r 0.21. For x > 0.21, the crystallinity decreased rapidly resulting in broad and asymmetric peak profiles and no reliable refinement was possible.…”

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confidence: 82%

Knowledge-based development of a nitrate-free synthesis route for Cu/ZnO methanol synthesis catalysts via formate precursors

et al. 2011

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High-performance Cu/ZnO/(Al 2 O 3 ) methanol synthesis catalysts are conventionally prepared by co-precipitation from nitrate solutions and subsequent thermal treatment. A new synthesis route is presented, which is based on similar preparation steps and leads to active catalysts, but avoids nitrate contaminated waste water.High concentrations of nitrate in aqueous solutions are environmentally harmful, require extensive waste water treatment, and-according to the principles of green chemistryshould be avoided during chemical synthesis processes. Industrial preparation of Cu/ZnO/(Al 2 O 3 ) catalyst 1 precursors by co-precipitation creates large amounts of concentrated nitrate waste water due to the application of nitrate salts as soluble metal sources. It is therefore highly desirable to find new synthesis routes for high-performance methanol synthesis catalysts. A variety of alternative methods, like citrate 2 or cyanide 3 precursor decomposition, sol-gel 4 or colloidal methods, 5 or mechano-chemical synthesis 6 have been reported in the literature. The big success, however, of the industrially applied conventional catalyst synthesis, which was introduced already in 1966 by ICI company, has so far prevented its substitution by usually less feasible or less successful alternative approaches.This success is based on a sequential meso-and nanostructuring of the catalyst precursor, 7 allowing a high dispersion of the active Cu phase as well as an intimate contact between Cu and ZnO, which is beneficial for the methanol synthesis activity of the resulting catalyst, 8-11 and on the highly optimized synthesis conditions. 12 In more detail, a mixed basic carbonate precursor, zincian malachite (Cu 1Àx Zn x ) 2 (OH) 2 CO 3 , is prepared by co-precipitation and ageing in form of needles. These needles decompose into nano-particulate CuO/ZnO mixtures upon calcination, in which the CuO component can be reduced to Cu(0) during the activation step. The precursor plays a key role for preparation of a good catalyst and one critical property is a low thickness of the crystallite needles on the order of the final Cu particle size (few nanometres), allowing high porosity of the resulting catalyst aggregates (mesostructure). In addition, a high Zn content x is desired, which, depending on the exact synthesis conditions, is around 0.3 in zincian malachite, allowing an effective nano-structuring and homogeneous Fig. 1 Cartoon of the industrially applied preparation of Cu/ZnO catalysts via needle-like zincian malachite precursors (a), SEM of the (Cu 0.78 Zn 0.22 ) 2 (OH) 3 HCO 2 precursor before and after calcination (b) and TEM of an ex-formate Cu/ZnO catalyst (Cu : Zn = 81 : 19); inset shows a power spectrum of the Cu particle (c).

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confidence: 82%

Knowledge-based development of a nitrate-free synthesis route for Cu/ZnO methanol synthesis catalysts via formate precursors

et al. 2011

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“…1,16,20,27,28 The optimum Cu : Zn molar ratio is close to 2 : 1, since 27 at% Zn is the maximum amount which can be substituted into the malachite lattice. 12,16,28 Higher Zn contents are desirable to facilitate further dilution of the Cu component, thereby enhancing synergistic interactions, but this results in a phase separated zincian malachite/aurichalcite precursor. However, it should be noted that aurichalcite and hydrotalcite precursors have been reported as being the optimum phases for producing catalysts for the LTS reaction.…”

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confidence: 96%

A new class of Cu/ZnO catalysts derived from zincian georgeite precursors prepared by co-precipitation

et al. 2017

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“…28,29 When some Zn 2+ ions were added (Cu/Zn molar ratio >2.7), single-phase rosasite with a general formula of ĳ(Cu,Zn) 2 ĲCO 3 )ĲOH) 2 ] can be obtained. 31 Addition of higher amounts of Zn 2+ ions (Cu/Zn molar ratio <2.7) results in the formation of aurichalcite which has a general formula of ĳ(Cu,Zn) 5 ĲOH) 6 ĲCO 3 ) 2 ]. The main difference between them is the orientation of the Jahn-Teller elongated axes of the CuO 6 octahedra.…”

Section: Brief Introduction Of the Precursorsmentioning

confidence: 99%

Efficient synthesis of 2,5-dihydroxymethylfuran and 2,5-dimethylfuran from 5-hydroxymethylfurfural using mineral-derived Cu catalysts as versatile catalysts

Zhu

Kong

Zheng

et al. 2015

Catal. Sci. Technol.

143

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Selective conversion of 5-hydroxymethylfurfural (HMF) can produce sustainable fuels and chemicals.Herein, Cu-ZnO catalysts derived from minerals (malachite, rosasite and aurichalcite) were employed for selective hydrogenation of HMF for the first time. High yields of 2,5-dihydroxymethylfuran (~99.1%) and 2,5-dimethylfuran (~91.8%) were obtained tunably over the catalyst with a Cu/Zn molar ratio of 2, due to the well-dispersed metal sites tailored by mineral precursors, well-controlled surface sites and optimized reaction conditions. The relationship between catalytic performance and catalyst properties was elucidated by characterization based on the composition and the structural and surface properties, and catalytic tests.The catalyst can also be extended to selective hydrogenation of other bio-derived molecules (furfural and 5-methylfurfural) to target products. The construction of mineral-derived Cu-ZnO catalysts and the revelation of the structure-performance relationship can be applied to further rational design and functionalization of non-noble Cu catalysts for selective conversion of bio-derived compounds.Catal. Sci. Technol. This journal is

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Structural Effects of Cu/Zn Substitution in the Malachite–Rosasite System

Cited by 94 publications

References 24 publications

Knowledge-based development of a nitrate-free synthesis route for Cu/ZnO methanol synthesis catalysts via formate precursors

Knowledge-based development of a nitrate-free synthesis route for Cu/ZnO methanol synthesis catalysts via formate precursors

A new class of Cu/ZnO catalysts derived from zincian georgeite precursors prepared by co-precipitation

Efficient synthesis of 2,5-dihydroxymethylfuran and 2,5-dimethylfuran from 5-hydroxymethylfurfural using mineral-derived Cu catalysts as versatile catalysts

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