US2339106A

US2339106A - Production of motor fuels

Info

Publication number: US2339106A
Authority: US
Publication date: 1944-01-11
Anticipated expiration: 1961-01-11

Description

Patented Jamil, 1944 2,339,106 PRODUCTION OF MOTOR. FUELS Mathias Pier, Heidelberg,

Mannheim, Germany;

erty Custodian N Drawing. Application No. 359,230, In Gem 1 Claim.

The present invention relates to a process for the production of motor fuels.

It is known that aliphatic hydrocarbon mixtures, boiling mainly within the boiling range of middle oils, 1. e., between about 200 and about 325 0., can be converted into low-boiling hydrocarbon oils of the gasoline type by cracking them in the presence of stationary catalysts. In this process, however, the catalyst loses efiiciency already after a short use owing to the deposition of high molecular weight polymerization products to such an extent that it must be reactivated or regenerated by the removal of these products. An excessive formation of undesirable deposits upon the catalyst can only be avoided by performing the reactivation of the catalyst after a short use for the reaction desired. It was only by the development of the catalytic destructive hydrogenation in the gas phase that it hecome possible to convert higher boiling hydrocarbon oils into low-boiling ones, practically without the catalysts sufiering a decrease of activity. jnlike the ordinary catalytic cracking process, however, the destructive hydrogenation must be carried out in apparatus capable of withstanding high pressures; besides, since hy drogen is consumed in the reaction provision must be made for its production.

We have now found that aliphatic hydrocarbon oils, substantially of the middle oil boiling range, can be cracked under such reaction conditions that, though hydrogen is present, it is not consumed, that high pressure is not needed, that the catalyst remains active for remarkably long periods oi time and that gaseous hydrocarbons I are formed to a comparatively slight extent only.

For this purpose, the initial materials, while in a vaporous state, are passed over one or more of the oxides of the metals of the 2nd to the 6th group of the periodic system, at temperatures between 420 and 560 C., together with hydrogen, under a total pressure between about 3 and about atmospheres and a hydrogen partial pressure amounting to at least 25 per cent of the total pressure, but to no more than half thereof, and the gases containing hydrogen leaving the reaction space are returned thereto, without adding fresh hydrogen, in an amount of from about 0.3 to about 2 cubic meters, preferably from 0.5 to 0.9 cubic meter, per kilogram of initial materlal.

As initial materials may be mentioned middle oils containing at least per cent, preferably from to per cent or more of parafflnic hydrocarbons. for example middle oils from paraffinand Ernst Donath.

vested In the Allen Prop- October 1, 1940, Serial any October 4, 1939 base mineral oils or, in particular, hydrocarbons of the boiling range of middle oils which are obtained by the reduction of carbon monoxide, as

vwell as middle oils obtained by the destructive oxide or most suitably on active alumina. Natural or artificial aluminum and/or magnesium silicates, which may he provided with a metal oxide, especially one of those named alcove, may also be employed.

The partial pressure or" the hydrogen advantageously amounts to about from 25 to 35 per cent oi the total pressure which may range from about 3 to about 25, more particularly from 5 to it atmospheres. if too large amounts of undesired gases, especially gaseous hydrocarbons, as for example methane, should collect in the gases returned to the reaction space, these may be removed, either wholly or partly, example by washing. For this purpose, from the gases leaving the reaction space, part may he branched oil and purified and the resulting hydrogen returned to the reaction space, either alone or in conjunction with unpuri'fied gas, Fresh hydrogen is required merely the outset or the operation,

but nothing is added during the operation; there is no need, therefore, of means for the preparation of hydrogen.

In contrast to the destructive hydrogenation. the process according to the present invention naturally requires the catalysts to be reactivated from time to time: however, the desired operation may last considerably longer than when working in the absence of hydrogen, for instance it may last for at least 2 hours, generally from 4 to 20 hours and may even last for substantially longer periods of, for example, several days. It may be of advantage to pass the gas containing hydrogen which is returned to the reaction space for some time over the catalyst at the reaction temperature without an addition of initial material, whereby the catalyst is reactivated in part and the requirement of a complete reactivation further put oil.

The reactivation is accomplished in known manner by means of gases containing oxygen, the

vated temperature and, if desired, under pressure. The catalysts mentioned above may be reactivated many times.

The hydrocarbon oils obtained by a single pass through the reaction chamber consist to the A paraiflnic middle oil obtained by the hydrocarbon synthesis from carbon monoxide and hydrogen, having a boiling range from 200 to 335 C. and an aniline point of 87 0., is passed over a catalyst consisting of active alumina with 6 per cent of molybdenum trioxide under a total pressure of 25 atmospheres, together with 0.6 cubic meter of circulation gas. The hydrogen partial pressure is about 40 per cent of the total pressure and the reaction temperature is 510 C. The catalyst, which is used in the form of pieces, is slowly passed through the reaction chamber in the same direction as the gases and vapors, so that its time of sojourn in the reaction vessel is about 14 hours. The catalyst, withdrawn from the catalyst chamber, is reactivated by oxidation with air at temperatures not exceeding '70 0. and used again.

Besides 16.5 per cent of gaseous hydrocarbons, a liquid product is obtained containing 44 per cent of gasoline and 56 per cent of middle oil. The gasoline has an octane number of 64 and contains per cent of constituents boiling up to 100 C. It contains 29 per cent of aromatic hydrocarbons and only 1.5 per cent of olefines. The middle oil boils between 200 and 343 C. and is strongly aromatized as compared with the initial material, which fact is evidenced by its aniline point of C.

What we claim is:

In a process for the production of knockresistant motor fuels from hydrocarbon oils by catalytic vapor phase cracking at elevated temperatures and pressures in the presence of hydrogen and recycling of hydrogen-containing reacted gases, the improvement which comprises using in combination an aliphatic starting material boiling mainly within the boiling range of middle oils, an oxide of a metal selected from the 2nd to the 6th group of the periodic system as the catalyst, a temperature of 420-560 C., a total pressure of 3-25 atmospheres, a hydrogen partial pressure of 25% to of the total pressure and a gas recycle ratio of 0.3-2 cubic meters per kilogram of starting material, partly reactivating the catalyst by passing the hydrogen-containing recycle gas over the catalyst at the cracking temperature without the addition of initial material and completely reactivating the catalyst after a reaction time of at least two hours.

MA'I'HIAS PIER. ERNST DONATH.