Ethylene kinetic measurements

We see in these formulae that the kinetically measured velocity constant has only in one special case, namely, in the case of zero order, the meaning of a real velocity constant. In all the other cases, it contains implicit adsorption coefficients, e.g., in the form kb = const., or (in retarded reactions) kb/b = const. Only in the case of broken order is it possible to determine k and b separately from kinetic measurements, as e.g., Schwab and Zorn (5) did for the ethylene hydrogenation. 

In a recent study (4) kinetic measurements in a CSTR were combined with simultaneous in situ measurement of the thermodynamic activity of oxygen adsorbed on the catalyst by using the technique of solid electrolyte potentiometry (SEP). The technique originally proposed by C. Wagner (1) utilizes a solid electrolyte oxygen concentration cell with one electrode also serving as the catalyst for the reaction under study. It has already been used to study the oxidation of ethylene on Ag (5) and on Pt (6). 

The anionic polymerization of thiiranes appears to proceed very clearly and in a well defined manner. Living systems have been found and good kinetic measurements have been possible [36]. The base catalysed polymerization of ethylene sulphide (ES) was probably one of the earliest thiirane polymerizations noted. However, the studies have been hindered because the polymer formed is highly crystalline and insoluble. Homogeneous solution studies have not been possible. Propene sulphide (PS) on the other hand gives soluble amorphous polymer and has been amenable to careful study. Indeed the formation of amorphous polypropene sulphide is the major evidence that base catalysed polymerization is ionic and proceeds by the reactions indicated by the equations... 

The kinetics measurements of the ethylene hydrogenation have been carried out in an isothermal rotating basket reactor. 

In general, chemisorption will produce new spectral bands which are not characteristic of the adsorbate or the adsorbent. However, absence of such bands cannot be taken as evidence of an absence of chemisorption. A difficulty present in any attempt to make kinetic measurements is that extinction coefficients are often significantly altered as a result of adsorption. These changes, which cannot as yet be interpreted theoretically, make it difficult to correlate the observed absorbance with the coverage of adsorbed molecules. The change in extinction coefficient is dependent on both the adsorbate and the adsorbent. For example, an increase of e was observed with increasing coverage for ethylene adsorbed on copper oxide, whereas the reverse occurred with nickel oxide . ... 

Atomic selenium was monitored in flashed CSe2 by kinetic absorption spectroscopy, and its rate of reaction with ethylene was measured in the temperature range 302-412 K. The rate of appearance of a new spectrum in the far ultraviolet (intense bands at 2259 and 2208 A) was symmetrical with atomic decay, and was assigned to ethylene selenide, i.e. selenirane (1) (Equations (la) and (lb)). Absorption spectra of flashed CSe2 and alkene mixtures show band systems in the 2000-2300 A region which do not occur in flashed saturated-hydrocarbon and CSe2 mixtures. The band centers obtained from their spectra are listed in Table 4. 

An internal-reflection prism cell has been used for reaction-kinetics measurement of styrene-unsaturated polyester resins at elevated curing temperatures and pressures [133]. Other researchers have estimated the cross-linking efficiency in methyl methacrylate-ethylene glycol dimethacrylate copolymer networks by laser Raman spectroscopy [134], while recently... 

Recent experiments (211) have shown that the lamellar thickness of poly(ethylene), PE, on oriented isotactic poly(propylene), changes from 16 to 39 nm upon annealing. This thickening is attributed to dimensional matching and secondary nucleation with the requirement (212) that the PE crystal(s) are thiimer than the PP dimension along the chain-row matching direction. However, no detailed kinetic measurements were reported on the rate of epitaxial growth here, or elsewhere in the literature. 

---