The precipitation of aluminium hydroxocarbonates powders from aqueous solution: Precipitate compositions and precipitation mechanisms

Packter, A.; Panesar, K. S.

doi:10.1002/crat.2170220805

Cited by 5 publications

(1 citation statement)

References 2 publications

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“…19 The use of the latter as a precipitation agent additionally leads to the formation of aluminium hydroxyl carbonates. 20,21 Carbonate species are reversibly adsorbed on the aluminium hydroxide planes, and their content is a function of pH and temperature. 22,23 In recent years, the role of methanol as a basic chemical has strongly increased, and therefore the further investigation and development of the ternary Cu/ZnO/Al 2 O 3 catalyst for methanol synthesis became more and more important.…”

Section: Introductionmentioning

confidence: 99%

On the precipitation mechanism and the role of the post-precipitation steps during the synthesis of binary ZnO–Al2O3 composites with high specific surface area

Kaluza

2009

J. Mater. Chem.

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Zinc oxide, aluminium oxide and binary ZnO-Al 2 O 3 composites were synthesized using a novel preparation method that combines continuous precipitation in a microreactor with an immediate spray drying process. The sequence of the post-precipitation processes as well as the type of drying can therefore be investigated in detail and turn out to be crucial parameters to achieve high specific surface areas. By optimizing those unit operations the formation of hydrotalcite during the synthesis can be suppressed resulting in an increase of the BET surface area up to 144 m 2 g À1 for the co-precipitated, washed, freeze-dried and subsequently calcined Zn-Al precursor.

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Section: Introductionmentioning

confidence: 99%

On the precipitation mechanism and the role of the post-precipitation steps during the synthesis of binary ZnO–Al2O3 composites with high specific surface area

Kaluza

2009

J. Mater. Chem.

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The coprecipitation of magnesium aluminium hydroxocarbonate powders from aqueous solution: Precipitate compositions and coprecipitation mechanisms

Packter

Panesar

1989

Cryst. Res. Technol.

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Magnesium aluminium hydroxocarbonate hydrates were coprecipitated from mixed metal nitrate solutions, a t total Cfi~ = 0.2 M and Mg/Al, = 1 ratio, with four sodium hydrogen carbonate-sodium carbonate solutions (of p H 8.1 to 11.5) a t ambient temperature. The course of precipitation was monitored by potentiometric (pH) titration, and the compositions of the primary and final precipitates were determined by chemical analysis, infrared spectrophotometry and X-ray diffraction.Precipitation generally occurred through three stages, primary precipitation (of low CO, aluminium hydroxocarbonates) at low pH with evolution of carbon dioxide, their dissolution by complexing to form hydroxocarbonatoaluniinate anions and then secondary precipitation of the final coprecipitate a t higher pHs. The final product from coprecipitation by sodium hydrogen carbonate solution (pH 8.1) was mainly the magnesium hydroxocarbonatoaluminate 'MAHC I' ; the final products from coprecipitation by sodium hydrogen carbonate-sodium carbonate solutions (pH 9.4 and 10.3) were 'MAHC

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Numerical modeling of injection and mineral trapping of CO2 with H2S and SO2 in a sandstone formation

et al. 2007

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Abstract. Carbon dioxide (CO 2 ) injection into deep geologic formations could decrease the atmospheric accumulation of this gas from anthropogenic sources. Furthermore, by co-injecting H 2 S or SO 2 , the products respectively of coal gasification or combustion, with captured CO 2 , problems associated with surface disposal would be mitigated. We developed models that simulate the co-injection of H 2 S or SO 2 with CO 2 into an arkose formation at a depth of about 2 km and 75°C. The hydrogeology and mineralogy of the injected formation are typical of those encountered in Gulf Coast aquifers of the United States. Six numerical simulations of a simplified 1-D radial region surrounding the injection well were performed. The injection of CO 2 alone or co-injection with SO 2 or H 2 S results in a concentrically zoned distribution of secondary minerals surrounding a leached and acidified region adjacent to the injection well. Co-injection of SO 2 with CO 2 results in a larger and more strongly acidified zone, and alteration differs substantially from that caused by the co-injection of H 2 S or injection of CO 2 alone. Precipitation of carbonates occurs within a higher pH (pH > 5) peripheral zone. Significant quantities of CO 2 are sequestered by ankerite, dawsonite, and lesser siderite. The CO 2 mineral-trapping capacity of the formation can attain 40-50 kg/m 3 medium for the selected arkose. In contrast, secondary sulfates precipitate at lower pH (pH < 5) within the acidified zone.Most of the injected SO 2 is transformed and immobilized through alunite precipitation with lesser amounts of anhydrite and minor quantities of pyrite. The dissolved CO 2 increases with time (enhanced solubility trapping). The mineral alteration induced by injection of CO 2 with either SO 2 or H 2 S leads to corresponding changes in porosity. 2Significant increases in porosity occur in the acidified zones where mineral dissolution dominates. With co-injection of SO 2 , the porosity increases from an initial 0.3 to 0.43 after 100 years. However, within the CO 2 mineral-trapping zone, the porosity decreases to about 0.28 for both cases, because of the addition of CO 2 mass as secondary carbonates to the rock matrix. Precipitation of sulfates at the acidification front causes porosity to decrease to 0.23. The limited information currently available on the mineralogy of naturally occurring high-pressure CO 2 reservoirs is generally consistent with our simulations.

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The precipitation of aluminium hydroxocarbonates powders from aqueous solution: Precipitate compositions and precipitation mechanisms

Cited by 5 publications

References 2 publications

On the precipitation mechanism and the role of the post-precipitation steps during the synthesis of binary ZnO–Al2O3 composites with high specific surface area

On the precipitation mechanism and the role of the post-precipitation steps during the synthesis of binary ZnO–Al2O3 composites with high specific surface area

The coprecipitation of magnesium aluminium hydroxocarbonate powders from aqueous solution: Precipitate compositions and coprecipitation mechanisms

Numerical modeling of injection and mineral trapping of CO2 with H2S and SO2 in a sandstone formation

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