Platinum solution

Ruch and Bartell [84], studying the aqueous decylamine-platinum system, combined direct estimates of the adsorption at the platinum-solution interface with contact angle data and the Young equation to determine a solid-vapor interfacial energy change of up to 40 ergs/cm due to decylamine adsorption. Healy (85) discusses an adsorption model for the contact angle in surfactant solutions and these aspects are discussed further in Ref. 86. 

Determination as metallic platinum Discussion. The platinum solution is treated with formic acid, best at pH 6, and the precipitated platinum weighed. A 2 per cent solution of hypophosphorous (phosphinic) acid may also be used as the reducing agent. 

Schuldiner, determination of the capacitance of platinum-solution interfaces, 129... 

Tennant investigated it carefully m an attempt to alloy lead with it, and concluded that it contained a new metal (17). In the autumn of the same year H.-V. Collet-Descotils, a friend and pupil of N.-L. Vauquelin, found that this powder contains a metal which gives a red color to the precipitate from an ammoniacal platinum solution (18). When Vauquelin treated the powder with alkali he obtained a volatile oxide which he believed to be that of the same metal with which Descotils was dealing (19). 

To a solution of hydrogen peroxide, add some of the colloidal platinum solution. The catalytic action of the finely divided platinum is plainly evidenced by the evolution of oxygen. 

Figure 13.5 Potential modulated reflectance spectrum of p-aminonitrobenzene (PANB) on platinum (solution phase 0.5 mM Na2S04 + 0.05 mM PANB). Applied dc 0.44 V vs. SHE. Modulation amplitude 50 mV. Modulation frequency 33 Hz. Incidence angle 65°. 11 signifies incident polarization parallel to incident plane and perpendicular to electrode surface. J signifies incident polarization perpendicular to incident plane (hence parallel to electrode surface). [From Ref. 50.]...

Triethylamine was obtained in a yield of 16% by alkylating ethylamine drop by drop with acetaldehyde in a 1 2 molar ratio in a colloidal platinum solution at room temperature and 0.1 MPa H2.12 Benzyldiethylamine was prepared in a 31% yield from ethylamine, benzaldehyde, and acetaldehyde in a 1 1 1 molar mixture over a colloidal platinum in H20-AcOH-EtOH at room temperature and 0.3 MPa H2. The yield of the tertiary amine, however, was improved to more than 50% by alkylating ethylbenzy-lamine with acetaldehyde. 

Carbon monoxide combines with oxygen to yield carbon dioxide when shaken at ordinary temperatures with colloidal platinum solution,1 whilst hydrogen and oxygen gases unite under similar conditions to yield water.2... 

In our process we make use of a 10% solution of hydrochloroplatinic acid for preparation of our colloidal metal, and precipitate the activated metal in aU aqueous solution of gum arabic by reduction with hydrogen gas without first introducing any colloidal metal to promote the reduction of the platinum chloride solution. Skita used in many cases a promoter to stimulate the formation of colloidal metal (Impfmethode). This was prepared by reducing platinum solution with formaldehyde in alkaline solution. 

Studies In our laboratories (43-51) have concentrated on the effects of quaternary salts on electrochemical oxidations on platinum electrodes In emulsion and micelle systems. In addition studies have been made of the effect of these surfactants on a noncatalytlc process occurring at the platinum solution Interface. The quaternary salt used for most of the experiments was Hyamlne 2389 (predominantly methyldodecylbenzyl trlmethylammonlum chloride) and the aqueous solution was strongly basic. Under these conditions It was concluded (49) that the anode was covered... 

Ion adsorption. A catalyst was also prepared by dispersing the support in an aqueous solution of (NH4)2PtCl4 (Acros). The Pt concentration (10 M) and the initial loading in solution (3 vrt%) were kept identical to those used in the DP method. The TiOz support was poured into the platinum solution (pH 4.3) heated at 60°C. The suspension was stirred at room temperature for 2 h, during which electrostatical interactions and exchange reactions were expected to occur between the charged surface and the ionic precursor. The filtered product was washed 4 times with distilled water, dried in a vacuum oven at 60°C for 18 h and finally heated 4 h at 300°C in a flowing mixture of Hz/He (10/90). 

The filtered platinum solution is heated in a beaker or porcelain vessel and treated with NH4CI. The (NH4)3ptCla deposit is then filtered off and extracted by boiling with distilled water to dissolve any small quantities of (NH4)3Pdda still remaining. 

Other experimental method at a eomparable level of detail, although in some eases the conclusions reached support previous work by XANES using synchrotron radiation. Our results clearly demonstrate that due to a quantum mechanical electron density spillover from platinum, the interface is metallized, as evidenced by Korringa relaxation and Knight shift behavior. Thus, the adsorbate on a platinum electrode belongs to the metal part of the platinum-solution interface, and most likely other d-metal interfaces, and should be considered as such in any realistic models of the structure of the electrical double layer of interest to electrocatalysis. 

One hundred and thirty-five milliliters of this platinum solution is added to a 320 g quantity of the deionized silica sol of Example 1 as there described including the addition of a polyethylene glycol. 

As demonstrated in the previous Section, temperature effects on platinum] solution interphases can be rigorously characterized through the evaluation of the entropies of formation of the interphase and double-layer. Moreover, these results can be employed to obtain an independent evaluation of the entropy of charge-transfer adsorbed species. 

In situ optical techniques should be considered as a very im-poitant tool, because of their natural compitability with the usual configuration of electrochemical cells. The limiting factor is always a model of optical signal, and a lot of important experimental results for platinum/solution interface still wait for physically grounded interpretation. 

Second harmonic generation (SHG) of platinum/solution interface was pioneered by Com and coworkers,who managed to get the resportse of hydrogen adatoms and coadsorbed anions despite platintrm signal is rather low as compared with SHG of Cu, Ag and An. Frrrther steps " resulted in a nttmber of particular... 

Platinum/solution interface is also studied by some techniques with less comprehensible background, like contact electric resistance. " Probably the progress of other techniques can later result in some clarification of the meaning of these data. The same is related to immersion techniques applied to determine the potentials of zero charge. "" Who knows, probably what looks mistaken now can be helpful later, when the nature of disagreement of various techniques shall be interpreted. 

Scheffer states that the new element is not one of the six metals hitherto known in aU countries. It is not gold or silver and does not contain copper, tin, lead or iron. It is a seventh metal, a new noble metal, as resistant as gold and silver. It is hard but also malleable. He observed - like Lewis and Marggraf- that when ammonium chloride was added to a platinum solution in aqua regia a red precipitate was formed. This... 

If the concentration of the platinum solution is decreased in geometrical proportion from 2 to 1, the reaction constant decreases from 3 to 1. The reaction is of the first order, although the constant [decreases considerably during the reaction. The rate is increased by small amounts of alkali, but large amounts retard it. It is noteworthy that the effect of alkalis on platinum and enzyme solutions is very similar, as shown by Fig. 19. 

The platinum hexachloroplatinic acid was used as precursor (Aldrich), usually employed in the preparation of supported catalysts. The aqueous solution was prepared shortly before impregnation and kept in dark bottle due to the instability of the platinum solution when exposed to light. Figure 7.14 shows the platinum particles of the Pt/Al2 O3 catalyst observed by TEM [12] and particle sizes as shown in Table 7.2. 

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