Fast‐Geomimicking using Chemistry in Supercritical Water

Abstract

Herein we introduce a powerful and fast method to produce nanominerals using a bottom up approach. The supercritical hydrothermal flow synthesis is exploited to produce model nanominerals by mimicking natural environments at high temperatures under pressure. This innovative concept is demonstrated with the talc synthesis; this represents a major technical breakthrough since it allows decreasing the mineral-synthesis time from tens of hours to tens of seconds. Through this example, we show these nanominerals exhibit new crystal-chemistry signals and new properties. This approach provides a means to reproduce the early stages of formation of minerals in different natural environments from sedimentary environments (low temperature and pressure) to hydrothermal/metamorphic environments (high temperature and high pressure).

Local and Extended-Order Evolution of Synthetic Talc during Hydrothermal Synthesis: Extended X-ray Absorption Fine Structure, X-ray Diffraction, and Fourier Transform Infrared Spectroscopy Studies

“…Each series was composed of the talc precursor sample (PT) obtained at room temperature and talc samples (T) synthesized at 100, 200, and 300°C for 1 or 6 h. Table 1 More details about the talc precursor preparation are available in the examples of the synthetic talc patent. 2 The talc precursor was centrifuged and rinsed to remove sodium salt before being freezedried. The Ni-talc precursor then underwent three different hydrothermal treatments at 100°C (<1 bar), 200°C (15 bar), and 300°C (85 bar) for 1 or 6 h according the procedure described in the synthetic talc patent.…”

Continuous Synthesis of Nanominerals in Supercritical Water

“…One of the most interesting solutionist he nanotalc synthesis in supercritical water.D umas et al enlightened the first talc synthesis combining ac ontinuous set-up with the use of supercritical water. [47,48] To perform the talc synthesis in only few tens of seconds,a mixture of silicon and magnesiumi nw ater,w ith aS i/Mg ratio equivalent to the Si/Mg talc ratio, is introduced in ar eactor at 400 8Ca nd 25 MPa. [48] During the synthesis, synthetic nanotalc is trapped in af ilter as ag el form.Aset of synthetic nanotalc was obtained in 10-23 seconds in near-or supercritical water.…”

“…This study reveals an ultra-fast structuration of synthetic nanotalc( Figure 5). [47] Synthetic nanotalc is an ew material defined by ah igh chemical purity,ananosize ( Figure 6) and ah ydrophilic character. [47] Figure 7i llustrates the crystal size coherency (estimated from the Scherrer relation) [49] which indicates the number of stacked layers in the c* direction( estimated from the 001 and 003 reflections) or the expansion of particlesi nt he (ab) plane (calculated from the 06'-33' reflection) flawless.…”

“…[47] Synthetic nanotalc is an ew material defined by ah igh chemical purity,ananosize ( Figure 6) and ah ydrophilic character. [47] Figure 7i llustrates the crystal size coherency (estimated from the Scherrer relation) [49] which indicates the number of stacked layers in the c* direction( estimated from the 001 and 003 reflections) or the expansion of particlesi nt he (ab) plane (calculated from the 06'-33' reflection) flawless. These diagrams show ac rystallinity of the product obtained in continuous at 400 8Ca nd at 470 8Ci n2 0seconds comparable to at alc synthesized in batch at 300 8Cf or 2hours and 6hours, respectively.T hese resultsd emonstrate the "booster" effect of the supercritical domain on the crystallinity of talc particles.…”

Continuous Hydrothermal Flow Synthesis of Co1–xNixFe2O4 (x = 0–0.8) Nanoparticles and Their Catalytic Properties for CO Oxidation and Oxygen Evolution Reaction

“…As a result, a high degree of supersaturation is achieved and nucleation starts almost instantaneously upon mixing. To date, various types of nanomaterials prepared by CHFS have been reported, including oxides, metals, sulfides, metal organic frameworks (MOFs), layered double hydroxides, and minerals , . In addition, upscaled operations at industrial level have been proven at pilot scale, in a full commercial plant (Hanwha Chemical Corp., Republic of Korea), and in the European FP7 project SHYMAN (http://www.shyman.eu).…”