Monophasic solid

The Sb Mossbauer parameters (79) of tin-antimony oxides calcined at 600°C were related to the preparative procedure. The white precipitates, formed in alkaline media that contain hydrated tin(IV) and antimony(V) species, were considered to dehydrate after 16-hr calcination at 600°C to give blue, poorly crystalline, highly defective rutile type solids. The Mossbauer spectra revealed the presence of tin(IV), antimony(V), and anti-mony(III) species in oxygen environments and were consistent with the dehydration process inducing the reduction of antimony(V) as is observed in the pyrolysis of antimonic acid (26) and the transformation of the tin(IV) hydroxide gel to tin(IV) oxide (30). The coexistence of random arrays of such units in a noncrystalline monophasic solid is consistent with the X-ray diffraction study (72) that described these materials as single-phase amorphous solids. 

The shoulder can be attributed to a deeper reduction leading to Fe°. For the HT monophasic solid, it can be seen two H2-consumption peaks at ca. 387 and 687°C. The peak, at lower temperature, could be due to the reduction of Ni species and the one at higher temperatuie to Fe into Fe species and probably, in less extent, to the reduction of Fe to the metallic oxidation state. The hydrogen consumption, during TPR, is similar for all samples (14-15 mmol.g ). The HT-sample reduction, starting at lower temperature, is in agreement with the smallest grain size observed by SEM for this solid. 

In perovskite-type catalysts the formation of the final phase is completed already at 973 K. XRD and skeletal FTIR/FTFIR data for LalCol, LalMnl and LalFel calcined at 973 K evidence that only LalFel-973 is actually monophasic and consists of a perovskite-type phase with orthorombic structure. A perovskite type phase with hexagonal-rombohedral structure represents the main phase of LalCol-973, but traces of C03O4 and La2C05 are also present. In the case of LalMnl-973 two phases have been detected both with perovskite-type structure, one orthorombic and the other rombohedral. The calculated cell parameters of the dominant perovskite-type phase are reported in Table 1 for the three samples. The results compare well with those reported in the literature [JCPDS 37-1493, 32-484, 25-1060] which refer to similar samples prepared via solid state reartion. All the perovskite-type samples are markedly sintered... 

The use of the "closed system" to describe the assemblages in these closed basins seems justified in that frequently, most always, in fact, the number of clay minerals present in the sediments discussed above is two or more. The omnipresence of amorphous silica or chert raises the total number of phases to three. In an essentially three-component system, Mg-Si-Al or possibly four if H+ is considered, this indicates that the chemical components of the minerals are present in relatively fixed quantities in the chemical system which produces the mineral assemblages. None of the first three components is "mobile", i.e., its activity is independent of its relative mass in the solids or crystals present. However, there are sediments which present a monophase assemblage where only one variable need be fixed. Under these conditions sepiolite can be precipitated from solution and pre-existing solid phases need not be involved. 

Similar to the AlCl3/[EMIM]TFSA mixture, the mixture of AlCh/IPyip] TFSA shows biphasic behavior with increase in the concentration of AlCh up to 1.6 M. In contrast to the AlQj/tEMIMJTFSA mixture, the lower phase is colorless while the upper one is pale and more viscous. By adding more AICI3 the volume of the lower phase decreases till a concentration of 2.7 mol L-1 is reached, then only one solid phase can be formed at room temperature. The biphasic mixture of AlCb/ITyi TFS A becomes monophasic by heating to a temperature of about 80 0 C. The electrodeposition of aluminum occurs only from the upper phase at AICI3 concentrations > 1.6 mol L . 

The first step is the split of the initial mixture in essentially monophase submixtures, as gas, liquid and solid. This operation, called the first separation step, can employ simple flash or a sequence of flashes, adsorption/desorption and reboiled stripping, or the combination of the above techniques. Next, the process synthesis activity can be further handled by specialized managers, namely gas split manager (GSM), liquid split manager (LSM) and solid split manager (SSM). 

Fig. 1 a-c Biphasic solid/liquid separations of a soluble polymer a beginning with a biphasic mixture of reactants and polymeric catalyst but with an intermediate monophasic reaction mixture and a biphasic solid/liquid separation b beginning with a monophasic mixture of reactants and polymeric catalyst, with an intermediate monophasic reaction mixture but with formation of a biphasic mixture of polymer and products that is separated or c beginning with a biphasic mixture of reactants and polymeric catalyst that remains biphasic throughout the reaction and through the separation stage... 

In practice, the nuances within this manifold of separation strategies reflect the fact that a reaction basically has three stages - the initial stage of the reaction, the time during the reaction itself, and the end of the reaction. At each stage, a polymeric catalyst can be present either as a solid with a soluble reactant, as a cosolute with a reactant in a monophasic reaction, or in one of two liquid phases in a biphasic mixture. The review below discusses recent examples... 

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