Hydrogen experiments

Alcorn and Sullivan (1992) faced some specific and difficult problems in connection with coal slurry hydrogenation experiments. Solving these with the falling basket reactor, they also solved the general problem of batch reactors, that is, a good definition of initial conditions. The essence of their... 

Table 4 summarizes the yield of soluble pitch for the hydrogenation experiments. Hydrogenation of WVGS 13407 at 350°C increased the pilch yield from about 66 to 84 wt% Although the incremental yield between untreated and hydrogenated coal is only 18 wt%, there were significant differences m the properties of the pitches in terms of their carbonization behavior. 

To determined if the ash removal steps could be simplified, experiments were performed on hydrogenated coals. Hydrogenation experiments were conducted at 400°C in tetralin and the piteh isolated from the insoluble mmeral matter and... 

Because hydrogenation of the double bond does not involve any of the bonds to the chirality center, the spatial ariangement of substituents in (-l-)-3-buten-2-ol must be the sane as that of the substituents in (-l-)-2-butanol. The fact that these two compounds have the sfflne sign of rotation when they have the sane relative configuration is established by the hydrogenation experiment it could not have been predicted in advance of the experiment. 

A process petrochemical plant producing a synthesis gas high in hydrogen experiences an explosion that results in the destruction of a 1500 cubic foot storage vessel normally held at 50 psig. Unprotected glass windows (i.e., no wire mesh reinforcing, nor tempered) in the plant area 150 feet away from the tank are broken. WTiat pressures were involved ... 

Hydrogenation experiments were conducted in a flow apparatus (Figure 5.24) at 97 °C using a pressure of 2 MPa [17]. A 10% solution of p-nitrotoluene in 2-propanol was the liquid phase as gas hydrogen (5.0 purity) was applied. The nitrotoluene flows normalized per unit area were 0.013 and 0.045 g h cm . The residence times were either 85 or 280 s. The recycle ratio was 21 or 43. 

Already after the first preliminary hydrogenation experiments, it became evident that diamino resorcinol carmot be manipulated in its base form, as contacting with traces of air it is oxidized, which appears in changing its pink color during seconds to daik purple. 

In a hydrogenation experiment starting with Pyroglu at 150 °C using two equivalents of base, Glu was formed as the sole product. 

The chemical and petrographic properties of the twenty coals used in the hydrogenation experiments are shown in Tables II and III. Mineral matter was determined directly using a radio frequency low temperature plasma asher at medium power rating for approximately 48 h per coal. The volatile matter was corrected for the effects of the mineral matter by applying the equation used by Given et al (5). 

Further detailed studies in this area are obviously needed to resolve the chemistry involved. Such pyrolysis studies supplemented by hydrogenation experiments with acid-form and salt-form brown coals offer promise of resolving the precise role of pyrolysis in the hydrogenation of these coals and of how the ash-forming cations participate in the hydrogenation reactions. 

The atom % 2H values of the solvent-fractionated products are also shown in Table I. In previous hydrogenation experiments conducted without the use of a donor solvent (1,18), deuterium incorporation increased from the most soluble oil fraction to the insoluble residue. In E10 and El9, contact of the coal with Tetralin resulted in a uniform incorporation of deuterium in almost all of the four product fractions. In El9, the BMI fraction s high value of 61 atom % 2H may be due to direct gas-phase exchange and deuteration. 

To summarize this section, the electrochemical hydrogenation experiments performed to date have yielded substantial penetration of low levels of hydrogen, but show promise for practical utilization despite temperature limitations and complications such as material removal. As with plasma and ion beam methods, the surface of this subject has barely been scratched. 

A comparison of the deuterium profile measured by SIMS and the spreading resistance profile obtained on deuterated samples is shown in Fig. 6. The region over which there is a reduction in thermal donor concentration matches well with the depth of deuterium incorporation. There is an excess of deuterium over the amount needed to passivate all the oxygen-donor centers. This is frequently observed in hydrogenation experiments and indicates there is hydrogen present in several states. 

One of the results of this variety in hydrogen-defect reaction pathways is that it largely clouds one of the hopes of the hydrogenation experiments, namely that the susceptibility of deactivation could provide information on the defect microstructure and the nature of the bonding with hydrogen. 

Extending partial copper passivation from one and two hydrogen atoms to three, one expects to obtain a fully passivated (Cu,H3) center. Strong support for the formation of such an electrically inactive center stems from hydrogenation experiments that have shown that the concentrations of all copper-related levels are reduced. Prolonged annealing in a vacuum regenerates the various level (Pearton, 1982). 

The same authors also reported the dispersion of palladium nanoparticles in a water/AOT/n-hexane microemulsion by hydrogen gas reduction of PdClJ and its efficiency for hydrogenation of alkenes in organic solvents [79]. UV-visible spectroscopy and TEM analysis revealed the formation of Pd nanoparticles with diameters in the range of 4 to 10 nm. Three olefins (1-phenyl-l-cyclohexene, methyl trans-cinnamate, and trans-stilbene) were used as substrates for the catalytic hydrogenation experiments under 1 atm of H2 (Table 9.12). All of the Start-... 

It was concluded that the high selectivity observed in the hydrogenation experiments using 26 b is explained by the relatively strong coordination of the alkyne to the palladium center, which only allows for the presence of small amounts of alkene complexes. Only the latter are responsible for the observed minor amounts of ( )-alkene, which was shown to be a secondary reaction product formed by a subsequent palladium-catalyzed, hydrogen-assisted isomerization reaction. Since no n-octane was detected in the reaction mixture, only a tiny... 

The mechanism for the hydrogenation probably involves Rh-jt interaction with the unsaturated systems. The selectivity of competitive hydrogenation experiments has established the relative order of the interaction forces [3] ... 

Tab. 6.1 Selected hydrogenation experiments with polymeric amphiphiles (experimental data are listed in Scheme 6.2, R, =COOMe, R2=Me).

The competihve hydrogenation of alkyl-substituted arenes was also performed with lr(0) nanoparhcles [49]. Using toluene as a standard substrate, several toluene/ benzene and toluene/monoalkylbenzene hydrogenation experiments were conducted in order to determine the selectivity constants of the transition-metal nanoparticles. These selechvity constants can be used to predict the relative reactivity of any other couple of monoalkylbenzenes. A series of initial reaction... 

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