Optimum washing conditions for the preparation of Cu/ZnO/ZrO2 for methanol synthesis from CO hydrogenation: Effects of residual sodium

Suh, Young-Woong; Rhee, Hyun‐Ku

doi:10.1007/bf02706869

Cited by 14 publications

(9 citation statements)

References 9 publications

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“…This material is synthesized through the coprecipitation of a hydroxycarbonate (HC) precursor followed by calcination to form CuO/ZnO 4. 5 The properties of the activated catalyst are dictated by the kinetic details of the synthesis of the solid, that is, by the properties of the precursor HC material;3, 5–7 the catalyst retains a “chemical memory”.…”

Section: Characteristics Of the Hc Product From Microreactor Precipitmentioning

confidence: 99%

Continuous Coprecipitation of Catalysts in a Micromixer: Nanostructured Cu/ZnO Composite for the Synthesis of Methanol

et al. 2003

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Bulk catalysts are indispensable for the production of primary chemicals. A Cu/ZnO system, which has been tremendously improved through promotion with Al, is used for the lowpressure synthesis of methanol. [1][2][3] This material is synthesized through the coprecipitation of a hydroxycarbonate (HC) precursor followed by calcination to form CuO/ZnO. [4,5] The properties of the activated catalyst are dictated by the kinetic details of the synthesis of the solid, that is, by the properties of the precursor HC material; [3,[5][6][7] the catalyst retains a "chemical memory".The precipitation of large quantities of material is an illdefined process. Even under "constant" precipitating conditions, the chemical potential of the reagents are neither spatially nor temporally constant when a drop of the precipitating agent is added to the reactor in which precipitate and dissolved ions already coexist. During ageing, washing, and drying of the catalyst precursor, complex exchange reactions occur, particularly between the anions (carbonate/ hydroxide and hydroxide/nitrate). These exchange reactions are not controlled and thus result in variations in the properties of materials that are synthesized in a similar manner. [8] A remedy for such a situation could be a continuous precipitation process in which, in the shortest possible time, a precipitate is formed in a small volume of solution, and is then collected under inert conditions (room temperature, water) followed by conventional processing. The kinetically controlled steps of nucleation and growth are thus carried out under much more reproducible boundary conditions. Furthermore, one can hope to minimize ensuing processes such as redissolution, reprecipitation, and ion exchange.In our studies, a commercial microreactor designed for reactions in solution was used for the precipitation.[9] The reactor consists of a plate (with parallel channels approximately 100 mm long and about 200 m wide), which is sealed between two temperature-controlled plates. The reagent solutions (0.15 m metal nitrate and 0.18 m sodium carbonate; pH = 7.0) are combined in the channels at a constant throughput (5 mL min À1 ) under fully defined flow conditions (very short residence time and rapid, intense mixing in the reaction zone). Heat transfer is thus rapid and precise temperature control (328 K) is ensured. The product is collected in a cooled settling container and is processed with the conventional washing and drying steps, followed by calcination. In a future, improved version of this method, the postprecipitation steps of collection, washing, and drying could also be organized into a continuous processing system to produce an even more uniform product.The fundamental experiments described herein demonstrate that such a production scheme, which above all distinguishes itself from standard batch precipitation in that the precipitate is rapidly isolated from the reactive mother liquor, does not produce a worse catalyst. Thus, such a continuous (parallel) precipitation technique is possible.T...

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Section: Characteristics Of the Hc Product From Microreactor Precipitmentioning

confidence: 99%

Continuous Coprecipitation of Catalysts in a Micromixer: Nanostructured Cu/ZnO Composite for the Synthesis of Methanol

et al. 2003

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“…Effective synthesis of methanol has been investigated during the past decades since methanol is considered to be one of the materials that can overcome the forthcoming shortage of petroleum [4]. Methanol synthesis from CO/H 2 and CO 2 /H 2 mixtures using Cubased catalysts has received considerable attention and various reaction mechanisms have been proposed.…”

Section: Introductionmentioning

confidence: 99%

In situ IR studies on the mechanism of methanol synthesis from CO/H2 and CO2/H2 over Cu-ZnO-Al2O3 catalyst

Wang

Zhang

2010

Korean J. Chem. Eng.

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Methanol synthesis from CO/H 2 and CO 2 /H 2 was carried out at atmospheric pressure over Cu/ZnO/Al 2 O 3 catalyst. The formation and variation of surface species were recorded by in situ FT-IR spectroscopy. The result revealed that both CO and CO 2 can serve as the primary carbon source for methanol synthesis. For CO/H 2 feed gas, only HCOOZn was detected; however, for CO 2 /H 2 , both HCOO-Zn and HCOO-Cu were observed, and without CH 3 O-Cu. HCOOZn was the key intermediate. A scheme of methanol synthesis and reverse water-gas shift (RGWS) reaction was proposed.

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“…It was assumed that small NO3 -residue inhibits the formation of HT-CO3. Also, the washing effect on the removal of sodium ion was studied as shown in Figure 8 [47]. As the Na content increased up to 1.7 wt%, the methanol selectivity in CO hydrogenation was maintained and the further increase declined the methanol selectivity drastically.…”

Section: Step 3: Filtering and Washingmentioning

confidence: 99%

Preparation of Active Cu/ZnO-based Catalysts for Methanol Synthesis

Jeong¹,

Suh²

2016

Applied Chemistry for Engineering

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In recent years, methanol has attracted much attention since it can be cleanly manufactured by the combined use of atmospheric CO2 recycling and water splitting via renewable energy. For the concept of "methanol economy", an active methanol synthesis catalyst should be prepared in a sophisticated manner rather than by empirical optimization approach. Even though Cu/ZnO-based catalysts prepared by coprecipitation are well known and have been extensively investigated even for a century, fundamental understanding on the precipitation chemistry and catalyst nanostructure has recently been achieved due to complexity of the necessary preparation steps such as precipitation, ageing, filtering, washing, drying, calcination and reduction. Herein we review the recent reports regarding the effects of various synthesis variables in each step on the physicochemical properties of materials in precursor, calcined and reduced states. The relationship between these characteristics and the catalytic performance will also be discussed because many variables in each step strongly influence the final catalytic activity, called "chemical memory". All discussion focuses on how to prepare a highly active Cu/ZnO-based catalyst for methanol synthesis. Furthermore, the preparation strategy we deliver here would be utilized for designing other coprecipitation-derived supported metal or metal oxide catalysts.

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Optimum washing conditions for the preparation of Cu/ZnO/ZrO2 for methanol synthesis from CO hydrogenation: Effects of residual sodium

Cited by 14 publications

References 9 publications

Continuous Coprecipitation of Catalysts in a Micromixer: Nanostructured Cu/ZnO Composite for the Synthesis of Methanol

Continuous Coprecipitation of Catalysts in a Micromixer: Nanostructured Cu/ZnO Composite for the Synthesis of Methanol

In situ IR studies on the mechanism of methanol synthesis from CO/H2 and CO2/H2 over Cu-ZnO-Al2O3 catalyst

Preparation of Active Cu/ZnO-based Catalysts for Methanol Synthesis

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