Supportive conversations timing importance

The products were solvent fractionated into hexane soluble (HS), hexane insoluble-benzene soluble (HI-BS), and benzene insoluble (Bl) fractions. The yields of these solvent-fractionated products after hydrotreatment of SRC are plotted against the reaction time in Fig. 13. The overall activities of the catalysts were very similar to those of the commercial catalyst in spite of their lower surface areas. Both exploratory catalysts (Cat-A and Cat-B) showed similar reaction profiles, which were markedly different from those of the commercial catalyst. The BI fraction decreased over the exploratory catalysts equally as well as the over the commercial catalyst. However, the HS fraction hardly increased as long as the BI fraction was present. As the result, the HI-BS fraction increased to a maximum just before the BI fraction disappeared and then rapidly decreased to complete conversion after about 9 hr. The rate of HS formation increased correspondingly during this time. Thus, the exploratory catalysts were found to exhibit a preferential selectivity for conversion of heavier components of SRC, compared to the commercial catalyst. These results emphasize that the chemical and physical natures of the support are important in catalyst design (49). 

A time-resolved ion yield study of the adenine excited-state dynamics yielded an excited-state lifetime of 1 ps and seemed to support the model of internal conversion via the nn state along a coordinate involving six-membered ring puckering [187]. In order to determine the global importance of the tict channel, a comparison of the primary photophysics of adenine with 9-methyl adenine will be useful, as the latter lacks a tict channel at the excitation energies of concern here. The first study of this type revealed no apparent changes in excited-state lifetime upon methylation at the N9 position [188] a lifetime of 1 ps was observed for both adenine and 9-methyl adenine. This was interpreted as evidence that the tict is not involved in adenine electronic relaxation. 

The initial activity of the carbon and alumina supported catalysts are compared in Table 2. The alumina supported catalyst is five times more active than the carbon supported one which is even less active than alumina alone. Nevertheless, carbon and alumina display an important difference of selectivity in the products of the conversion of methoxyphenol. The production of phenol is reported in Fig. 2 as a function of the production of hydroxyphenol for the two catalysts. The catalyst supported on carbon produces much less rapidly hydroxyphenol than the alumina supported one while it has a slightly higher activity for the production of phenol. The result is a much higher phenol to hydroxyphenol ratio. 

Supported Cobalt Catalysts. Experiments were conducted with [Co(PC)]/Si02 at 340°C to determine the important variables for the catalysis of a typical [M(PC)]. Table IV gives the results for runs which were conducted for varying periods of time. It is seen that even at 100 hr. the conversion only reached 36%. The equilibrium conversion at 342°C can be estimated to be 97%. (9) Thus, the reaction is quite far from equilibrium even at long times. This may be taken as evidence for product inhibition of the catalysis. This might be expected since tetrahydroquinoline is a stronger Lewis base than quinoline. Thus, the product could bind to the metal center and prevent activation of the substrate and/or hydrogen. One important conclusion is that the reaction is not over in 24 hours and it can be assumed that the difference in conversions noted in Table I with different [M(PC)] are due to differences in inherent activity of the [M(PC)]. 

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