Isoprene, hydrogenation

Isoprene Hydrogenation on Palladium Black Influence of Diethylsulfide... 

In the isoprene hydrogenation results of Table XII, the ratio of the 1,4 addition/1,2 addition decreases on palladium with sulfur addition. Such a result is not at all in accordance with other studies dealing with nickel... 

Table 6 Initial reaction rates of styrene and isoprene hydrogenation measured as rates of substrate disappearance) and compositions of reaction products at half-life of sub-...

Esterified polystyrene-co-maleic anhydride Polyethylene-co-propylene Poly(ethylene-co-propylene diene-modified) Poly(ethylene-co-propylene-co-olefin diene-modified) Hydrogenated polystyrene-co-butadiene Hydrogenated polystyrene-co-isoprene Hydrogenated polyisoprene. 

The catalysts were tested in isoprene, benzene and naphthalene hydrogenation reactions. The catalysts prepared by oxidation of the intermetallic at 703 K were found to be more active than those oxidized at room temperature. In isoprene hydrogenation the catalyst based on mischmetal has a larger activity than the other alloys and is comparable to the catalysts prepared by other routes. In benzene hydrogenation the Ni and Ce based catalysts prepared by coprecipitation were found the most active. In naphthalene hydrogenation the fully oxidized intermetallics are four times more active than the partially oxidized ones. In addition they are independent of hydrogen pressure and selective into decaline formation. 

The initial selectivity will be independent on the pressure of B. Moreover, if the ratio k K4 CB/ ki is small enough, the selectivity remains essentially equal to unity up to high conversions, decreasing thereafter. The character of selectivity beyond the point of high conversions will be pressure dependent, so that at higher pressures (concentrations) of B, the selectivity towards C will be lower. Such dependencies have been observed for isoprene hydrogenation over a palladium catalyst (Figure 4.26). 

Figure 4.26. Selectivity as a function of conversion in isoprene hydrogenation at different ratios Pje/Pf 1- 0.7 2 -6.5 3- 10. (S.L. Kiperman, Foundations of chemical kinetics in heterogeneous catalysis, Moscow, Chimia, 1979)...

The reaction of [Bu3Sb] in heptane solution with a reduced Pd/Al203 catalyst yields a supported alloy. " When these final solids are reduced at 573 or 773 K, the second metal locates preferentially at the outer layer of the bimetallic aggregates. After reduction at 773 K, large metallic aggregates are obtained (particle size around 15 nm). The specific activity of the Pd surface atoms for isoprene hydrogenation is then lowered and the selectivity increased. 

During isoprene hydrogenation, iron added by ionization of preadsorbed hydrogen promoted the activity of Pd/Al203 catalysts while the opposite effect was observed when iron was introduced by co-impregnation or successive impregnations [67,... 

Platinum catalysts have given product distributions that were not consistent with the mechanism that seems to apply to palladium." " Isoprene hydrogenation has also been performed on Pt(lll) at 423 K, 5tot was very low (37%). Raney nickel has also been used." ... 

Second virial coefficient of poly(isoprene), hydrogenated... 

In 2-methyl-l,3-butadiene (isoprene) hydrogenation, 2-methyl-2-butene resulting from 1,4 addition of H atoms is the main product on solid base hydrogenation catalysts. Deuteration, however, results in the formation of ( ) and (2) forms of 2-methyl-2-butene-d2- The ratio of ( ) form to (2) form varies with catalyst types, and informs us of the dynamic nature of the intermediates in the reaction. The dynamic... 

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