DE1418654B - Process for the isomerization of up to 10 wt .-% methylcyclopentane containing C deep 6-paraffin hydrocarbons - Google Patents

Description

1 2

The isomerization of paraffinic hydrocarbons which can be removed is the process according to FIG

In the gasoline boiling range, a known method of the invention is relatively simple, but has considerable

Increasing the octane number of gasoline fractions. Remaining advantages. Since methylcyclopentane and cyclo-

Hexane hexane isomers are particularly suitable for this treatment, a reversible reaction takes place

or pentane-hexane fractions. These fractions are held, which indicate the proportions of each compound in the

But not only normal and inoparaffins hold, reaction zone determined; the removal of cyclo-

but also cycloparaffins that do not improve hexane out of the system shifts the reaction in

and can even be disadvantageous in the isomeric direction of a further conversion of methyl

affect the sation process. From the following cyclopentane in cyclohexane. In this way, the

led to boiling points of various C ₆ carbon io enrichment of methylcyclopentane and slowed down

Hydrogen can be seen, however, that methylcyclo- even effectively kept below an upper limit

Pentane boils so close to η-hexane that a separation will be caused by the equilibrium between the

of the two compounds by fractional distillation two cycloparaffins under the iso-

tion is practically impossible. merization conditions is determined. At one too

"-. T ^ - ι n *. "" "" 15 strong accumulation of cycloparaffins can

2,2-Dimethy butane 49.7 C cycle can be interrupted for a time.

, -Uimetliylbutan Λ '" _ο ^ The method is suitable for the treatment of

2-Methy pentane ^ 'oo- typesetting materials, their content of methylcyclopentane

3-methylpentane «.30 is _{less than} 10 percent by weight. Fractionation

?: ^H f ^ ⁿ ·, · S ' _o ^ so to remove cyclohexane from the product

Methylcyclopentane 71.8 C _{is advantageous with one or} more

^ f ⁰ / Qn7 ° r fractionation columns carried out fractionation

Cyclohexane SU, / C _{for the} separation of the desired isoparaffins combined

If, therefore, an isomerization process does not interfere. If, for example, a C ₆ fraction is treated in a process for the separation of hydrocarbons, the product can be combined into an overhead fraction which contains types of substances, for example with selective adsorption on dimethylbutane, an intermediate fraction, the molecular sieves, finds the isomeri - η-hexane and any existing methylcyclopentan sation in the presence of cycloparaffins instead, and, contains and which is recycled, and what is more important, if the unreacted products cyclohexane are separated from the bottom fraction are recycled, the cyclo - 30 The methylpentanes can be found in the head or intermediate paraffins in the system. This problem has already been discussed in a fraction - preferably the latter - in U.S. Patent 2,905,736. To the detriment, since they can be further converted into the higher octane dimethylbutanes, preventing the undesired build-up of cyclo-. A complete separation of paraffins is proposed there, so much hydrocarbon material 35 is not possible from the material cycle between the dimethylbutanes and methylpentanes, since the boiling points are to be separated close together that the range is undesirably higher, so that the fractions are not pure in practice Cycloparaffins concentrations are not reached.

will. According to this U.S. patent proposal The feed to the isomerization process

However, not only is cycloparaffin, but can also be fractionated to remove

mix with it also a proportion of the non-cyclic Pa- 40 cyclohexane and optionally of isoparaffins, the

Refined hydrocarbons are in the process cycle and do not require conversion, e.g. B. of dimethyl

thus withdrawn from the overall proceedings. This will cause butanes to be subjected. In this case, before

inevitably a reduction in the yield of the desired isomerization zone, a single fractionation system

th connections. used in which the insert is introduced and

In contrast, the invention proceeds from the task to which the reaction product is returned. There

position, by taking suitable measures to build up the boiling points of cyclohexane and benzene tightly

an undesirably high concentration of cyclo- lie together, there is the possibility that a

to prevent paraffins without the desired Pa- certain amount of benzene from the use with the cyclo-

refined hydrocarbons hexane is removed from the process cycle if the feed contains benzene,

to have to remove. 50 The removal of benzene by fractionation is

The invention therefore relates to a process, however, through the formation of an azeotropic mixture

for isomerizing up to 10 percent by weight Me- complicated, and the use is before the fractionation

ethylcyclopentane-containing Ce paraffin hydrocarbons, preferably treated by other methods,

substances by heating in the presence of hydrogen to remove any benzene present. On that

and catalysts, with unconverted Pa- 55 being discussed in more detail below.

The preferred catalysts for isomerization and an enrichment of the methylcyclopentane present in the isomerization process of the invention are an aluminum stage, halide and a hydrogenating metal on a heat that is characterized by being resistant Oxide as a carrier. The process is isomerized in the starting material at 65-177 ⁰ C and 60 performed the presence of hydrogen,
product obtained by distillation into a base material containing essentially only cyclohexane is preferably used as the halide in the catalyst, but aluminum fraction, an η-hexane and methylcyclopentane bromide can also be used. The middle fraction containing aluminum halide and a top fraction containing dimethylbutane are preferably separated in an amount of 3 to 20% by weight, based on the catalyst, and methylcyclopentane consisting of n-hexane 65%. The halide can be recycled into the catalyst to the isomerization step. by working with aluminum halide

Because cyclohexane is brought into contact by known fractionating methogenide vapors. A roughly-

Any excess of aluminum halide can then be removed by heating.

All metals of groups VIa and VIII of the Periodic Table can be used as the hydrogenation metal known to be effective. Preferred is a platinum group metal, e.g. B. Platinum or palladium, which is present in an amount of 0.01 to 5.0 percent by weight.

The heat-resistant oxide used as a carrier is aluminum oxide, which is expediently made from an aluminum alcoholate will be produced. The hydrogenation metal can be used during or after the preparation of the aluminum oxide be incorporated into the catalyst, for example during hydrolysis, in a slurry or in a gel of hydrated alumina or after calcination. Becomes a If the metal of the platinum group is used as the hydrogenation metal, it is preferably added by precipitation Metal from a solution with hydrogen sulfide.

The isomerization is carried out under the following conditions in the liquid or vapor phase:

Temperature 65 to 177 ⁰ C

Pressure normal pressure

up to 141 kg / cm ² , ^

preferably 16.8 to 41 kg / cm ² room flow velocity - 0.05 to 10, preferably

speed, V / V / h 0.2 to 5

Hydrogen molar ratio 0.01 to 20: 1, preferred Hydrocarbon preferably 1.5 to 15: 1

In addition to the ^ hydrocarbons, the insert can also contain C ₅ and / or C ₄ hydrocarbons. It is useful if the insert is practically free from benzene, as this is a catalyst poison. The benzene content of the insert is preferably below 0.1 percent by weight, especially below 0.01 percent by weight. The benzene can be removed by acid treatment or other known methods or converted to cyclohexane by hydrogenation. When the benzene is converted to cyclohexane it is particularly convenient to use the process according to the invention. It is also advantageous if the insert is practically free of water and sulfur, the sulfur content preferably being below 0.001 percent by weight. These two substances can be removed by any suitable method.

example

A dry, desulphurised and dearomatised hexane cut from a light gasoline that is made from crude oil from the Middle East was obtained, was isomerized over a platinum-aluminum oxychloride catalyst, the Contained 0.56 percent by weight platinum and 15 percent by weight aluminum chloride. The following working conditions were used:

Temperature 149 ° C

Pressure 36 kg / cm ²

Space flow rate 1.0 V / V / h

Molar ratio hydrogen
to hydrocarbon 3.5: 1

The key figures of the use and the product are listed in Table 1 below:

Table 1

propane

Isobutane

η-butane

Isopentane

n-pentane

2,2-dimethylbutane
2,3-dimethylbutane

Cyclopentane

2-methylpentane

3-methylpentane ....

η-hexane

Methylcyclopentane
Cyclohexane

mission product track Weight percent track track - 1.5 track 0.5 0.5 21.0 1.5 36.0 track 17.5 28.5 18.0 22.5 2.5 41.0 3.0 4.0 2.0

The product obtained in a yield of 95.5 percent by weight was in a column with 40 trays at a reflux ratio of 20: 1 into an overhead product and a soil fraction separated. The bottoms were in a second 40 tray column distilled further at a reflux ratio of 20: 1, wherein an overhead fraction, which was suitable for recycling into the isomerization reactor, and an out Cyclohexane was obtained, which was suitable for the production of benzene. The values for these distillations are listed in Table 2 below.

table

Column 1 y Column 2

fraction

Head product | Soil product | Head product | Bottom product yield in percent by weight based on input 33.6 I 66.4 I 97.0 I 3.0

Composition in percent by weight

propane

Isobutane

η-butane

Isopentane

n-pentane

2,2-dimethylbutane

2,3-dimethylbutane

Cyclopentane

2-methylpentane

3-methylpentane

η-hexane

Methylcyclopentane

Cyclohexane

track
1.0

track
5.0
3.0

59.0

30.5
1.5

2.0
43.5

26.0

22.0

3.5

3.0

2.0 45.0

26.5

23.0

3.5

track

Lane 100.0

From Table 1 it can be seen that the methylcyclopentane under the isomerization conditions in cyclohexane is converted, and Table 2 shows that virtually all of the cyclohexane is fractionated can be removed from the product. Table 2 also shows that by the distillation as well an overhead product rich in 2,2-dimethylbutane and a mainly η-hexane and methylpentane containing recycle stream can be obtained.

Claims (1)

Claim: IO Process for isomerizing up to 10 percent by weight of methylcyclopentane-containing C _e paraffin hydrocarbons by heating in the presence of hydrogen and catalysts, unconverted paraffins being returned to the isomerization stage and an enrichment of the methylcyclopentane present in the isomerization stage is prevented, characterized in that the Starting material is isomerized at 65 to 177 ° C and the resulting product is separated by distillation into a bottom fraction containing essentially only cyclohexane, a middle fraction containing η-hexane and methylcyclopentane and a top fraction containing the dimethylbutanes, and the middle fraction consisting of η-hexane and methylcyclopentane is separated into the isomerization stage returns.