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Abstract  

Chemical reduction of hematite with starch in air at elevated temperature was investigated using X-ray powder diffraction, FT-IR and 57Fe Mössbauer spectroscopies. On heating the starting mixture for 0.5 and 2 hours at 300 °C, magnetite and a small fraction of hematite were identified by XRD. With the heating time prolonged up to 24 hours, magnetite reoxidized and hematite was obtained again. The formation of magnetite was observed even at 580 °C. However, the magnetite formed at this temperature was substoichiometric, as shown by XRD and Mössbauer spectroscopy. Characteristic IR bands of oxide phases were monitored by FT-IR spectroscopy. Chemical reduction of hematite with starch into a Fe0 state was not observed in any sample.

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Abstract  

Results of Carr and Galwey [1] concerning copper malonate (CM) decomposition in vacuo at 510 K prompted present studies on the utility of CM as a low-temperature precursor of oxide-supported copper catalysts. CM deposited upon metal oxides has been converted to copper particles by vacuum thermal decomposition or reduction with aqueous hydrazine. Using the dehydrogenation of isopropanol to acetone as a catalytic probe reaction, comparisons are made between levels of catalytic activity and selectivity induced in TiO2, MgO and Ca(OH)2 supports by copper deposited thereon. Effects of particle size, prereduction temperature, and support reducibility are described and evidence is given for a strong metal support interaction (SMSI)-like inhibition of activity of Cu/TiO2 by prior high temperature reduction.

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. Effect of temperature on nitrate reduction Temperature is an important factor in chemical reduction that may provide some insight into the mechanisms of the reactions evaluated in this study [ 35 ]. Controlled chemical reactions are often

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Abstract  

The thermal decomposition of electrolytic manganese dioxide (EMD), in an inert atmosphere, and the effect of chemical reduction on EMD, using 2-propanol under reflux (82C), was investigated by differential scanning calorimetry (DSC). This study is an extension of a study investigating the thermal decomposition of EMD and reduced EMD by TG-MS (J. Therm. Anal. Cal., 80 (2005)625)). The DSC characterisation was carried out up to 600C encompassing the water loss region up to 390C and the first thermal reduction step. Water removal was observed in two distinct endothermic peaks (which were not deconvolved in the TG-MS) associated with the removal of bound water. For the lower degrees of chemical reduction, thermal reduction resulted in the formation of Mn2O3; for higher degrees of chemical reduction, the thermal reduction resulted in Mn3O4 at 600C. In the DSC the thermal reduction of the EMD and chemically reduced specimen was observed to be endothermic. The reduced specimens, however, also showed an exothermic structural reorganisation.

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Resolution and Discovery
Authors:
Svetlana Jovanovic
,
Olaf C. Haenssler
,
Milica Budimir
,
Duška Kleut
,
Jovana Prekodravac
, and
Biljana Todorovic Markovic

into water (200 mL) and filtrated until the pH was 7. Chemical reduction of both GO and GQDs was conducted using in situ generated hydrogen [ 7 ]. Synthesized GQD and GO were dispersed in water in a concentration of 1 mg/mL and the ccHCl acid (35

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–Ni–Mo–B amorphous catalysts with various cobalt contents were prepared by chemical reduction. Adding proper cobalt in Ni–Mo–B catalyst, the particle size became smaller and the relative content of MoO 2 on the catalyst surface was increased. The addition of cobalt

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Abstract  

Fe–B ultrafine amorphous alloy particles (UFAAP) were prepared by chemical reduction of Fe3+ with NaBHO4 and confirmed to be ultrafine amorphous particles by transmission electron microscopy and X-ray diffraction. The specific heat of the sample was measured by a high precision adiabatic calorimeter, and a differential scanning calorimeter was used for thermal stability analysis. A topological structure of Fe-B atoms is proposed to explain two crystallization peaks and a melting peak observed at T=600, 868 and 1645 K, respectively.

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To synthesize nickel(0) nanoparticles by wet chemical reduction using hydrazine with an average size distribution below 100 nm, two different reactor concepts were developed. With a cone channel nozzle, the reactant solutions were sprayed into a batch for further processing and reduction at elevated temperatures. Another concept uses a micro-coaxial injection mixer connected to a heated tube to establish a fully continuously operating reactor. To shorten the time for reduction of the nickel, salt temperatures up to 180 °C are applied. To avoid uncontrolled residence time, the whole system was pressurized up to 80 bar. Approximately 80 L reactant solution, i.e., 1 kg nickel(0) nanoparticles, could be processed within 30 h.

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Abstract

Co–Mo–O–B amorphous catalysts were prepared by the chemical reduction method and characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), inductively coupled plasma (ICP) and X-ray photoelectron spectroscopy (XPS). The hydrodeoxygenation (HDO) properties of these catalysts were tested using phenol as the model compound. The catalyst preparation time had no influence on their amorphous structure but a great effect on the catalyst surface composition and the HDO activity. With the prolongation of preparation time, the catalyst particle size and the relative content of Co on the catalyst surface were increased gradually. The conversion of phenol could be as high as 100% with a selectivity of 99.6% for deoxygenation. The aromatics content in the products could be decreased to below 2% and the total H/C atomic ratio could be improved to 1.98. The pseudo first-order reaction rate constant of the phenol transformation on Co–Mo–O–B amorphous catalyst was high to 0.67 mL/(g catalyst s). The main reaction route in the HDO of phenol on Co–Mo–O–B amorphous catalyst proceeded with hydrogenation–dehydration rather than direct hydrogenolysis.

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