1.3 Process mechanism

There are several theories of the mechanism of course of the reactions of an isomerization based on type of the used catalyst i.e. depending on whether the bifunctional catalyst consisting of metal and the carrier is used or the catalyst which acidity is increased by means of halogen introduction is used. Regardless of type of the used catalyst at the intermediate stage there is a formation of a karbeniyevy ion or karbokation.

Reactions of an isomerization on bifunctional catalysts at presence of Hydrogenium can be described in general, having provided the following scheme of reaction:

Metal function of the catalyst (in this case due to platinum presence) consists in inducing of formation of olefins as the intermediate product by a dehydrogeneration of paraffin. Then transformation of olefins into karbeniyevy ions results from accession of a proton at adsorption on the acid surface of the catalyst.

Then there is a skeletal regrouping:

After a regrouping there is a desorption of a karbeniyevy ion in the form of an iso-olefin which then is exposed to hydrogenation under action threw - lichesky function of the catalyst with formation of iso-paraffin:

Bifunctional catalysts of a hydroisomerization which work at very low temperatures are characterized by more strong acid centers in comparison with catalysts for which operation high temperatures are required bo-leu. In this case, according to this theory, the karbeniyevy ion is formed as a result of a direct separation of a gidridny ion from paraffin under the influence of acid function of the catalyst.

After a skeletal regrouping isopentane is formed, and the chain uvelichi-is howled due to formation of the new acid center.

1.4 Key parameters of process

There are three main variables of technological process exerting immediate impact on overall performance of reactors:

- temperature in the reactor;

- rate of volume flow of supply of raw materials;

- fractional pressure of Hydrogenium.

1.4.1 Temperature in the reactor

Temperature increase promotes increase in activity of the catalyst and an approximation to equilibrium, however reduces equilibrium quantity of an isomer in grocery mix of the reactor. Also at temperature increase intensity of an isomerization increases, but to a particular limit. Further temperature increase leads to strengthening of reactions of hydrocracking with formation of light hydrocarbons. Hydrocracking is followed by increase in a consumption of Hydrogenium; resultants of reaction contain mainly components of a normal structure.

1.4.2 Rate of volume flow of supply of raw materials

At constant extent of transformation rate of volume flow renders antibate (counter each other) influence on isomerization speed. Increase in rate of volume flow twice requires process temperature increase approximately on 8-11 °C.

1.4.3 Fractional pressure of Hydrogenium

Hydrogenium relation to hydrocarbons is defined as quantity of moles of Hydrogenium on escaping of the reactor on each mole of fluid raw materials. Such relation interferes with adjournment of carbon on the catalyst, providing enough Hydrogenium for saturation of products of hydrocracking.