This series of experiments presents the well known fact about the different concentration increases as well as the different decreases of the conversion efficiency with the increasing pressure depending upon the kinds of catalysts in greater detail. At extremely high space velocities, the ammonia concentration remains constant independent of the change of the total pressure when the mixture of a constant gas ratio (H2: N2=3: 1) is used; however, it increases with increasing nitrogen pressure when the mixtures of different initial compositions are used at a constant pressure. As predicted by Temkin’s equation, the nitrogen percentage or hydrogen percentage, at which a maximum ammonia concentration or a minimum conversion efficiency is observed, shifts towards the higher percentage with the increasing space velocity; however, the nitrogen percentage corresponding to the maximum shifts further through the critical value predicted by Temkin. The shifting is-more or less rapid depending on the kind of catalyst. To the extent that the space velocity is very high and the total pressure remains constant the equation by S. L. Kiperman can represent the shifting in a better agreement together with the observed proportionality between the ammonia concentration and the reciprocal space velocity. The rate equations of M. I. Temkin and M. Shindo, which are based on different concepts, have been compared with the present results, and neither M. I. Temkin’s nor M-Shindo’s (unimproved) is in satisfactory agreement with the results. An equation based on the concept by M. I. Temkin and provided with another factor characteristic of the kind of catalyst has been proposed. The equation is in better agreement with the experimental results concerning the ammonia concentration expressed as functions of the space velocity and the pressure. The maximum of the ammonia concentration or the minimum of the conversion efficiency related to the ratio of hydrogen to nitrogen is represented in a somewhat better agreement with the singly promoted catalyst, while yet unsatisfactorily with the triply promoted.
(1) Isonicotinic acid methyl ester gives a single reduction wave and the half-wave potential shifts to more negative potential with increasing pH. (2) Isonicotinic acid methyl ester is saponified in the alkaline medium and the velocity constant of saponification is determined polarographically on the basis of the second order reaction equation. (3) The velocity constant is scarcely influenced by the addition of neutral salts, but increases with rising temperature. The activation energy of saponification is calculated according to the Arrhenius equation.
The irreversible photobleaching of eosine in the aqueous solution and in alcohol-water mixtures was studied and it was found that the rate of photobleaching depends only on and is proportional to the quantity of ab-sorbed light when the dye concentration is 10−5 mol./1. The overall unimolecular rate constant k or the quantum yield, when the quantity of dissolved oxygen is varied, does not change over a wide region but begins to decrease below a certain critical point. The values of k in water-alcohol mixtures were found to be expressed by the following equation in the low concentration region of alcohol. (Remark: Graphics omitted.) where k° is the rate constant of the pure aqueous solution and K is a certain constant. The possible schemes were given particularly on the bases of the rate formula (6) and of the effect of the quantity of dissolved oxygen. It is most probable that the irreversible photobleaching of eosine by oxygen is a successive reaction as represented by the following scheme Ib) D\xrightarrowhνD*→Dt\xrightarrowO2Dt···O2\xrightarrowH2O··· Product. In this case, the probability with which Dt···O2 is deactivated by alcohol is about 100 times greater than that of Dt···O2 being attacked by water. There is some possibility that the reaction may proceed in the following way. IIb) D\xrightarrowhνD*→Dt\xrightarrowH2ODt···H2O\xrightarrowO2··· Product Two cases corresponding to this scheme are possible. When a moderate fraction of Dt contributes to the reaction, the intermediate Dt···H2O must be deactivated by alcohol far more frequently than it reacts with oxygen, while when a very small fraction of Dt participates in the reaction, the probability with which Dt deactivated by alcohol is much larger than that of the reaction with water. The former case is rather improbable, while, the latter one seems to conform to a newly discovered fact that eosine in alcoholic solution is photobleached quite easily under evacuated conditions. The kinetic studies of the vacuum-state-photobleaching of eosine in alcohol, the comparison of the effects of various alcohols upon the rate of oxygen-water-bleaching and the measurement of the rate of the possible vacuum-bleaching in various alcohols, all these investigations now in progress will give a more definite conclusion.
Various aluminate phosphors were prepared and some of their emissions were measured. When activated by manganese, aluminate phosphors emit green, orange, or red light, while those activated by lead show blue or violet emission. Cerium acts as an activator only for calcium aluminate and emits violet light under ultraviolet excitation Strontium aluminate activated by manganese and lead shows a weak emission under short wavelength ultraviolet excitation. This may be caused by the double activation due to manganese and lead.
The amount of activators, which are now used for the present phosphors, was determined by means of polarography. The results obtained shows that manganese or copper is not dissipated during firing, while antimony or lead is dissipated in that period. As for calcium silicate phosphors activated by manganese and lead, the residual amounts of activators were analysed by polarography and, these amount being taken as the additional factorial effects, the analysis of covariance was carried out to see the effects of atmosphere and firing time on the brightness. The results obtained show that the amount of lead has a more significant effect upon the brightness than manganese and the change of atmosphere causes that of the amount of activators and the brightness.
The photopolymerization induced by the excited cyanine dyes was investigated, and it was established that the direct interaction between excited dye and monomer initiates the polymerization. The quantum yields for photobleaching and for the initiation process in the polymerization were both found to be of the order of 10−4. It was further found that one dye molecule produces one or two kinetic chains of polymerization.
Choosing pinacyanol iodide as a sensitizer, the authors studied the effects of temperature, concentration of dye and the wave lengths of incident light upon the photo-polymerization of styrene in a mixture of styrene and butanol (15:1). It was found that the number of initiation processes as for polymerization produced by one decomposed dye molecule is decidedly less than 1 at 40°C, while it is about 2 at 60°C, and, from this result and other facts, it was concluded that the initiation of polymerization and the photobleaching are not necessarily an identical process though the two processes are related quite closely. As for the probable scheme of the polymerization in light, it was proposed that the addition of dye and illumination only increases the initiation process without any effects upon the remaining processes in the polymerization. It was further found that, in favorable conditions, the fragment of decomposed dye molecule is attached to the polymer, which can also initiate the polymerization photochemically. A more detailed account of the experiments will be reported in Journ. Instit. of Polytech., Osaka City Univ.