Co-precipitation methods

It was reported that various catalysts and reductants have been utilized in DSRP for the SO2 reduction [1-5]. In this study, appropriate catalysts were developed for DSRP. The Sn02-Zr02 catalyst was prepared by co-precipitation method and used for the catalysts in DSRP. The characteristics of SO2 reduction were investigated with CO as a reducing gas. 

CO oxidation over Au/CeOi prepared by a co-precipitation method... 

The activity of the Au/metal oxide catalysts is extremely sensitive to the method of preparation. The Au/metal oxide catalysts were prepared by the co-precipitating method [1]. During the course of this study, we have determined that the activity and the stability of the catalyst for room temperature CO oxidation were a function of Ph of the solution, temperature of precipitation, aging temperature and time, catalyst wash procedure, and calcination. 

In order to confirm the hypothesis made on the role of catalyst components, we carried out the reaction with a ratile-type V/Sb/0 catalyst, having V/Sb atomic ratio equal to 1/1 (Table 40.1). This catalyst was prepared with the conventional sluny method, and therefore had a surface area of 10 mVg, lower than that obtained with the Sn/V/Nb/Sb/0 catalysts prepared with the co-precipitation method. However, despite this difference, with V/Sb/0 the conversion of n-hexane was similar to that one obtained with Sn/V/Nb/Sb/0. This is shown in Figure 40.7, which reports the conversion of n-hexane, the selectivity to CO2, to / -containing compounds and the carbon balance as a function of the reaction temperature. 

Ni-Fe/Fe204 with Ni/Fe ratio = 1-2.5 200-300 °C 0.2 g catalyst, 02/EtOH = 0-2 Total flow rate = 35 mL/min. catalysts with different Ni/Fe ratios were prepared by co-precipitation method. Among them, the catalyst with Ni/Fe = 1 was found to be the most active and selective for H2 at 300 °C, 02/EtOH = 1.5. The selectivity to CO decreased with increasing 02/EtOH ratio 108... 

Effect of Solvents on Photo-catalytic Properties of SnCh Nanoparticles Synthesized by Chemical Co-precipitation Method... 

SnC>2 nanoparticles have been successfully synthesized by chemical co-precipitation method using ethanol, acetone, tetrahydrofuran (THF) and ether as solvents. X-ray Diffraction (XRD), Field Emission Electron Microscopy (FESEM) and Transmission Electron Microscopy (TEM) have been used to study the crystallographic and morphological properties of synthesized SnC>2 nanoparticles, while their optical properties have been studied by UV-Visible absorption spectroscopy. UV-Vis absorption spectra shows a weak quantum confinement in all the synthesized SnCL samples. The photo-catalytic activity of as-synthesized SnC>2 nanoparticles under UV irradiation has been evaluated using Methylene Blue (MB) dye as a test contaminant in water. The results showed that solvents played a key role to control the morphology and photo-catalytic activity of SnCE nanoparticles. 

Cu-Mn mixed-oxide binary spinel catalysts (CuxMn3 x04, where x = 0, 0.25, 0.5, 0.75 and 1) prepared through co-precipitation method exhibit phenol methylation activity imder vapor phase conditions [75]. All of the catalysts, irrespective of the compositions, produced only C-methylated phenols. However, a total ortho selectivity of 100% with 2,6-xylenol selectivity of 74% was observed over x = 0.25 compositions at 400°C. This composition was found to be relatively stable under reaction conditions compared with the other compositions studied. The catalysts with high copper content suffered severe reduction under methylation conditions whereas, catalysts with low copper content had a hausmannite phase (Mu304) that sustained... 

The Unipnre Environmental, Unipnre process technology is a unique iron co-precipitation method for removal of heavy metals from waste streams or groundwater. It can act as a primary metal-removal system or as a polishing step to an existing treatment system. The reactor mod-nle replaces the nentrahzation tank in a conventional wastewater treatment system. The process prodnces solids that are extremely insolnble in water and mild acid solutions. 

Processing and Fabrication, Ceramics are traditionally prepared from powders formulated from the individual oxides however, early attempts to produce the PLZT powders by this method proved to be inadequate from the standpoint of chemical and optical uniformity. As a result, a chemical co-precipitation method designed specifically for the PLZT materials which utilized liquid precursor materials was developed and successfully implemented as a production process (15),... 

Unsupported V2Os—Mo03 catalysts were also studied by Bielanski and Ingolt [49,50], using an integral flow reactor at 350° C. Several hours of pre-treatment with the reaction mixture were needed to obtain a stable and selective catalyst (the catalyst was prepared from a melt instead of by the usual co-precipitation method). In this period, partial reduction and formation of V4+ (ESR analysis) take place. The activity increases with the actual V4+ concentration in the working catalyst (Fig. 7) until a 100%... 

Hence, there is already an abnormally high concentration of silica on the Ni(OH)a surface prior to the reduction, and this situation will persist after reduction. The phenomenon of silica skin formation according to this hypothesis is hence inherently connected with the co-precipitation method of preparing Ni-Si02 catalysts. 

DEAE-dextran. Like the calcium phosphate co-precipitation method, the DEAE-dextran technique was originally developed to increase the viral infectivity of animal cells, and its application was later extended to transfection processes. Although it is simple, efficient, and appropriate for transient expression, its use for stable transfections has not given satisfactory results. The transfection efficiency of this method can be increased by treating cells with glycerol or DMSO. The DNA is incorporated by endocytosis, and thus exposed to extreme pH levels and cellular nucleases, which may explain, to a certain extent, the high frequency of mutations observed when transfecting by this method (Calos et al., 1983). This transfection technique can be applied to both adherent and suspension cell lines. For detailed transfection protocols, the works by Keown et al. (1990) and Kaufman (1997, 2000) are recommended. 

The hydrophobic nano-MH was produced by the co-precipitation method [15] as described in Scheme 13.2 and a TEM image of the nanoparticle is shown in Figure 13.1. 

When impregnated with Ce(N03)3 solution and calcined the resulting catalysts are extremely active towards SOx abatement (Table I, Figure 4). The solid solution spinel catalyst is nearly 25% more active than the stoichiometric spinel catalyst. This can be explained by assuming that -MgO- structural fragments of the spinel are the chemisorption active sites (1). There are more active sites in Mg2Al20c than in MgA1 04. We also see that the catalyst prepared by co-precipitation method is 4 times more active than the catalyst prepared by the thermal co-condensation method. In Zone D we see that the sulfated catalyst is very effectively reduced by H. Nearly 70% of the absorbed species is reduced within 2 min. of reduction. 

The physical properties such as surface area and pore volume of these spinels are very similar to the ones prepared by co-precipitation method (Table I). 

Figure 3. X-Ray Diffraction Patterns of MgAl C (A) and Mg2Al2C>5 (B) Prepared by Co-Precipitation Method.

Compared to conventional solid-state reaction and co-precipitation method [1,2], sol-gel method offer promising approaches for preparing ultrafine, homogeneous, high-purity powders at temperatures far below other required methods. Currently, there are no literatures reporting that nanometer BaTiOj was used as support to prepare catalyst. In this paper, performance of the catalyst with nanometer BaTiO, as support in the reaction of CO2 reforming CH4 to syngas was described. 

The combination of ceria with another oxide from a group 111 metal (boria, alumina, gallia and india) using either a co-precipitation method or a sol-gel route has led to mixed oxide samples with specific acid-base and redox features, as evidenced by thermal techniques [91]. 

Three different Cr-Co spinels were prepared and tested as catalysts for the oxidation of methane in the presence of SO2, a typical catalyst poison. The spinels were prepared from nitrate precursors using a co-precipitation method, followed by calcining at three different temperatures, (400, 600 and 800 °C) for 5 hours. Characterisation results indicate that the catalyst calcined at 800 C presents a structure of pure spinel, whereas the presence of single oxides is observed in the catalyst calcined at 600 C, and the catalysts calcined at 400 C presents a very complex structure (probably a mixture of several single and binary oxides). Experiments show an important influence of calcining temperature on the catalyst performance. In absence of SO2, catalysts calcined at 400"C and 600 C performs similarly, whereas the activity of the catalysts calcined at 800 C is worse. When sulphur compounds were added to the feed, catalyst calcined at 600"C deactivated faster than the other two catalysts. 

The solid-state method requires high temperature heating or high mechanical energy for diffusion of reactants. Synthesis in liquid phase is useful to prepare solid compounds that contain the different cations in an ideally atomic dispersion. There are two methods concerning this concept one is a precursor method and the other is a co-precipitation method. 

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