Ethylene with heterogeneous catalysts from

This chapter has focused on inorganic and heterogeneous catalysts, because historically these are the major systems with which chemical engineers have been concerned. There are number of important homogeneous catalytic processes such as the Wacker process to make vinyl acetate from ethylene and acetic acid, and there are many acid and base homogeneous catalyst systems. 

The first report of the copolymerization of an epoxide, namely, ethylene oxide and C02 is contained in a patent by Stevens [6]. However, this process, when carried out in the presence of polyhydric phenols, provided polymers which were viscous liquids or waxes possessing copious polyether linkages with only a few incorporated C02 units. The earliest metal-catalyzed copolymerization of epoxides and C02 was reported in 1969 by Inoue and coworkers, who employed a heterogeneous catalyst system derived from a 1 1 mixture of diethylzinc and H20 [7, 8], Subsequently, Kuran and coworkers investigated a group of related catalysts prepared from diethylzinc and di- and triprotic sources such as pyrogallol, with a slight improvement over Inoue s system for the production of polypropylene carbonate) from PO and C02 [9],... 

For the commercial production of vinyl acetate, a procedure with a heterogeneous fixed-bed catalyst is exclusively applied today. The catalysts usually consist of palladium salts, mostly the acetate, or palladium metal together with alkali acetate supported on a carrier such as alumina, silica, or carbon without any additional oxidant. This process avoids the formation of larger amounts of by-products. Thus, from ethylene vinyl acetate and from propene, allyl acetate is obtained exclusively. 

Earlier and continuing work from our laboratories has shown that the introduction of small quantities of tetrachloromethane (TCM) into the feedstream for methane partial oxidation or oxidative coupling produces benefrcial increases in the selectivides to hydrocarbons, particularly ethylene, with many heterogeneous catalysts [19]. Consequently it is of interest to examine the effect of this additive with other oxidation processes, such as the conversion of CO to COj. 

Random copolymers of ethylene and ct-olefins (1-alkenes) can be obtained with Ziegler-Natta catalysts, the most important being those of ethylene and 1-butene (LLDPE) and ethylene with propylene (EPM or EPR and EPDM). Representative reactivity ratios are presented in Table 9.7. It is seen from these values that ethylene is much more reactive than higher alkenes, and the ratios vary with the nature and physical state of the catalyst. In most Instances, riV2 is close to unity. Heterogeneous Ziegler-... 

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