DE1086680B - Process for the radiochemical conversion of hydrocarbons - Google Patents

Description

Process for the radiochemical conversion of hydrocarbons The present invention relates to the conversion of hydrocarbons by Irradiation in the presence of activated carbon as a catalyst. The irradiation takes place mainly by gamma rays and / or neutrons.

In one embodiment, the catalyst is with a neutron trapping, alpha-particle-emitting material.

It is known to use hydrocarbons by means of ionizing radiation high energy, such as B. beta and gamma rays and neutrons, convert.

The use of radiation to carry out reactions provides a number of significant advantages over methods according to the previous state of the art of the technique. For example, it can be used to achieve desired equilibria in reactions which normally cannot be achieved by conventional means permit.

It has now been found that an activated carbon catalyst has a noticeable effect and surprising influence on the radiochemical conversion of hydrocarbons, in particular of petroleum hydrocarbons, such as. B. petrol and gas oils. It has surprisingly been found that an activated carbon catalyst which is known per se a carbon conversion process carried out under irradiation far beyond that Accelerates beyond what would normally be expected. It was further found that the activated carbon catalyst has a noticeable isomerization among the converted Hydrocarbons, especially hydrocarbons containing 4 to 10 carbon atoms, causes. This is surprising because one would normally have to assume that on these Free radical-generating type of catalyst due to low isomerization is.

The use of the activated carbon catalyst according to the invention is special advantageous when bombarding hydrocarbons in nuclear fission reactors, d. H. when bombarded with neutrons, because activated carbon has a very small neutron capture cross-section Has.

The invention can be applied to very different hydrocarbon feeds, like common crude oils, shale oils, tar sand oils, asphalt, synthetic (5le, natural and synthetic hydrocarbon gases, especially for the conversion of oils, which come from petroleum, such as. B. crude oils, distillate and residue fractions of these Oils, extracts or concentrates made from them, or mixtures thereof. A preferred one Feedstock is a petroleum distillate that ranges between about 65 and It boils at 510 ° C and is predominantly paraffinic in nature.

For example, the method according to the invention is for isomerization of light raw petrol useful for the purpose of increasing the octane number. It can also be used, as is known per se, to make waxes as lubricants to isomerize with a high viscosity index. By suitable selection of the feed and the operating conditions one obtains products that are in motor oils, as chemical Raw materials or as gasoline blending components are useful.

As is known per se, activated carbon catalysts can be calcined hard cellulosic materials such as B. coconut shells and apricot kernels, from chemical coke (a by-product in the production of colorless paraffin oils), from fluidized bed coke, from coal and from similar carbonaceous materials getting produced. The raw coal or coke have well-developed structures fine pores. These pores can be enlarged by various oxidizing agents reacting with the carbon, such as B. water vapor, oxygen, carbon dioxide, Sulfur. In general, the more active carbon product ultimately obtained will be the more active (larger surface, larger pore volume, larger adsorption capacity), the milder it is is the oxidizer. For example, oxygen settles at relatively low levels Temperatures easily react with carbon, but its action does not produce any particularly beneficial activated carbon. On the other hand is water vapor that is below approximately 650 ° C does not react quickly with carbon, an effective activating agent Temperatures of around 760 ° C and higher. Carbon dioxide required for conversion with the carbon at even higher temperatures, the activated carbon is the end product but a high quality catalyst.

The activated carbon catalyst which can be used in the present invention generally has the following properties: The surface area of the activated carbon catalyst is more than 50 m2 / g, preferably more than about 200 m2 / g, and the pore volume is at least 0, 20 cm3 / g. The specified surface area and pore volume values are determined with nitrogen according to the known Brunauer-Emmet-Teller (B. E. T.) method. The bulk density of the catalyst is preferably greater than 0.4 kg / l. The activated carbon catalyst can be used for a rest pouring in the form of granules of one size (clear mesh size) from 4.76 to 0.149 mm or finer, for a slurry of particle size in the range between 0.30 and 0.044 mm or finer and for a fluidized bed process mainly used with a particle size of 20 to 801 l. The temperature in the catalyst zone and the nature of the feed have a direct influence on the type of procedure used. The abrasion resistance of the activated carbon is not too important when working with a resting embankment; when working with slurries or vertebral layers, it is preferred that the loss due to abrasion is less than about 60 / o per hour, in particular less than about 3, 5% per hour, as after the Roller wear test (see Oil and Gas Journal, 1947, No. 46, p. 307), since activated carbons do not consist of pure carbon and a have residual ash content, which can be up to 40 / o or more, it is it is particularly desirable that the nature of these inorganic constituents be known, so that they will not cause any adverse effects if they are in the environment of a nuclear reactor.

Preferably the total neutron capture cross section is Coal catalyst and the impurities less than 75 barn.

In addition to the impurities inherent in the activated carbon, which either catalytically or as a result of their nuclear properties the conversion of hydrocarbons, the activated carbon catalyst can be smaller Additional amounts, less than about 10%, of catalytic components which are generally known as such in the art. Examples of such catalyzing additives are platinum, nickel, cobalt, copper, molybdates, oxides, tungstates, Chromates, phosphates and sulfides.

A particularly preferred embodiment of the invention consists in that smaller amounts of so-called »radiochemically catalytic Components «incorporated. Of particular interest are the isotopes t ° B and 6Li, which emit a strongly ionizing alpha radiation after capturing a neutron. You can use the pure isotopes, but the natural ones can also be used Occurring elements boron and lithium are used as they are significant amounts these isotopes contain. The isotopes can be used as pure elements or as compounds these elements are used.

Examples of such compounds are boron oxide (B203) and lithium oxide (Li2O). It is preferable to use less than 10 percent by weight lithium oxide and less than 2 percent by weight boron oxide, based on the catalyst. It is preferable to impregnate the active charcoal with these compounds or elements, them however, they can also be oil soluble in the hydrocarbon reactant in the form Connections such as B. boron triethyl, triphenylboron, phenyllithium and the I, ithiumsalz high molecular weight phenols.

The activated carbon catalyst can be used as a suspension in the liquid hydrocarbons or used as quiescent bed, as a fluidized bed or as a sinking layer will ; all of these methods of use are known in the art. If the catalyst is contaminated, it can by known methods, e.g. B. by burning, acid treatment, chemical processing, treatment with steam at high temperatures or by the aforementioned treatment with C 02 can be regenerated. The solid particles can be in place or outside the reactor, continuously or periodically regenerated as required.

The irradiation used according to the invention can be carried out by elementary particle accelerators, obtained from reactor waste products or products which, e.g. B. Cobalt 60, made particularly radioactive. For example, you can use spent fuel from a nuclear reactor or aluminum-clad cobalt rods that use a bombardment exposed to neutrons.

If radioactive materials are used, the average is Gamma ray flux in the reaction zone greater than about 105 roentgen per hour. the Reaction conditions are preferably also designed so that the hydrocarbon oil receives exposure to gamma rays of at least 106 X-rays. This material can be exposed to the action of the radiation source simply in that it is conducted in pipes through the radioactive material or past it or but by adding the radioactive material to the hydrocarbon being treated moved past.

However, it is preferred to use a nuclear reactor as the radiation source to use. In general, a higher radiation intensity is achieved, and the irradiation times can be shortened. The one obtainable through a nuclear reactor Neutron radiation also makes the conversion of hydrocarbons much easier. In this embodiment of the invention, the average gamma ray flux is in the reaction zone preferably more than 105 roentgen per hour and the average Neutron flux more than 10t ° neutrons / cm2 sec. The radiation dose obtained is preferably above about 107 X-rays; When using a nuclear reactor is the hydrocarbon oil simply by being in the fissile material or around this material is pumped around arranged pipes. cliché braking substances, such as carbon, light and heavy water are used to generate thermal neutrons. In some cases, the hydrocarbon reactant itself can act as a braking substance to serve.

The method according to the invention can be applied to conversion reactions apply, in which the hydrocarbon used as a reactant is wholly or partially in the gas phase. It will be most appropriate to responses is applied in the liquid phase and the pressure applied is therefore preferred sufficiently high to maintain essentially a liquid phase. The temperature can can be very different, the preferred range is between 93 and 482 ° C.

According to the drawing, hydrocarbons, e.g. B. an unedited Gas oil distillate, fed through line 1 to the process. One through the line 2 fed activated carbon catalyst is mixed with the gas oil, and the mixture is introduced into the irradiation zone 3. The amount of catalyst used usually ranges between 0.05 and 1.0 kg / kg of feed. The flow velocity the mixture is adjusted so that the above dosage is obtained.

In the arrangement shown, a suspension of the catalyst in the irradiated product through line 4 from the irradiation zone into the separation zone 5 transported. This separation zone contains devices through which the catalyst for example, is recovered by distillation, filtration and absorption. The recovered catalyst can optionally be fed directly through line 7 returned or discarded. Before repatriation he can first by burning, Steam treatment, chemical work-up and the like to remove Impurities and / or to improve its properties are treated.

The hydrocarbon products are also separated in zone 5. For example, distillation, extraction and absorption or similar procedures can be used. Optionally, a portion of the hydrocarbon product can be used be returned through line 6. The end product is withdrawn through line 8.

The separation zone 5 also contains devices through which the radioactivity the products are eliminated or neutralized. With these devices can they are radioactivity decay containers, ion exchange devices, Act as distillation columns, filters and solvent extraction systems.

The invention can be better understood from the following examples.

Example 1 The feed consisted of cetane. As an activated carbon catalyst Columbia G was used from the Carbide and Carbon Chemical Company Coconut shells and hard nuts with the following data: surface area 1397 m2lg, determined according to the standard B. E. T. nitrogen adsorption process, Bulk density 465 kg / m3, an abrasion rate of 2.6% hour (standard test according to Roller) and an ash content of 2.7%.

For comparison, an identical experiment was carried out using a Silica-alumina catalyst carried out. This silica-alumina catalyst was obtained by impregnating silica gel with an aluminum salt solution and precipitated the clay by adding ammonia. The hydrogel obtained was washed with water until it was free of dissolved salts. After drying in Oven and calcining at 540 ° C, the catalyst had the following data : Surface area 417 m2 / g (B.E.T. method); Pore volume 0.35 cm3 / g; Abrasion speed (Roller test) 2.5% / hour and an Al203 content of 13% and SiO2 of 87 ° / o.

For the irradiation of the samples the air-cooled, with natural Brookhaven National's uranium-powered and graphite-braked research reactor Laboratories used. The nuclear reactor was with a total performance of about 24 Megawatts operated at the time of the experiments. The flow of thermal neutrons in the reaction zone was 3, 4'10 / cmsec. The flow of fast neutrons (over 1 MeV) was 0.68 # 1012 / cm2 # sec, and the gamma ray flux was 1.8 106 roentgen / hour.

The core of the reactor consisted of a graphite grid with the dimensions from about 6-6-6 6 # 6 m, from its north face to its south face in the same Spaced in the reactor, aluminum-clad uranium rods with a diameter extended by 2.54 cm. The core was of a concrete shield about 1.5 m thick completely surrounded. The test holes used for irradiation consisted of square holes with an edge length of 10, 16 cm, which extend through the 1, 5 m thick concrete shield and another 3.05 m extended into the carbon core. the normal operating temperatures in the test hole were around 120 to 205 ° C. 600 each cc of the catalyst and the cetane were in one on a horizontal aluminum slide arranged aluminum container with a diameter of 7, 62 cm irradiated, the was provided with a vent pipe. The ventilation pipes made of aluminum extended from the vapor space in the containers to one outside the shield located test acquisition system. Gases and condensable liquids from the Vent pipes were measured and collected. The samples were scheduled during Decommissioning used in the nuclear reactor, irradiated for 10 days and then during the taken from the kiln following shutdown.

The following table shows the data for the gaseous products obtained during bombardment: Table I Silica Activated carbon Clay Mole percent H2 88.987.1 Mole percent hydrocarbon substances, calculated H2-free C1 ..................... 13, 7 9, 9 C2 33, 8 24, 6 C3 ll, l 23, 3 C4 20, 3 25, 4 Ces 15, 6 15, 0 Ratio of olefin to paraffin C2 1, 2 0 C 0, 0 0, 5 C4 0. 8 0.6 C5 0, 5 0, 3 Isoparaffin to ratio n-paraffin C4 ..................... 0.9 Ce 4, 4 20 Ingredient converted into gas rate, percent by weight ... 7, 4 5, 2 The absence of normal paraffins in the C4 and C5 range and the high ratios of isoparaffin to n-paraffin should be noted. The combination of neutron irradiation and activated carbon results in extensive isomerization of the fragments obtained by cracking.

Example 2 This example explains the catalytic properties of activated carbon with cetane when there is no irradiation by nuclear radiation. In this case and under the temperature conditions used in Example 1 above, namely at 120 to 205 ° C, neither activated carbon nor silica-alumina catalysts for the use of cetane have any catalytic effectiveness. At higher temperatures, namely about 343 ° C and more, cleavage takes place in the presence of these catalysts. The following table shows the data on the gaseous products obtained from cracking cetane at a temperature of 500 ° C. without irradiation: Table II Silica activated carbon Clay Mole percent H2 5, 0 9, 9 Mole percent hydrocarbon substances, calculated H2-free Cl 4, 6 13, 5 C2 11, 7 26, 0 Cs 32, 9 25, 4 C4 32, 7 19, 0 C5 18, 1 16, 1 Ratio of olefin to paraffin C2 ................. 1, 9 0, 3 C3 3, 6 0, 6 C4 2, 0 0, 5 1, 1, 9 0, 6 Isoparaffin to ratio n-paraffin C4 2.6 6 0.0 Cs 4, 7 0, 0 Isoolefin to ratio n-olefin C4 .................... 0.7 0.0 C5 1.5 0.0 Converted to gas (C5) Use, percent by weight 10, 0 9, 2 Attention should be paid to the complete absence of iso-olefins and iso-paraffins in the cleavage products when using an activated carbon catalyst.

Since the feed material in this case is cetane (normal Ci6H34) shows the fact that there are no isomers in the cleavage products branched chain occur that activated carbon under the structural isomerization does not favor the cracked products.

A comparison of the data in Tables I and II shows the by Radiation in the case of activated carbon Differences caused by the catalyst. the High yield of branched products shown in Table I with activated charcoal The chain must be traced back to the combined effect of the activated carbon and the radiation will.

The distribution of the cetane with a silica-alumina catalyst obtained cleavage products is not too different from that of normal cracking 500 ° C, compared with the product distribution when cracking at 177 to 204 ° C under irradiation. It should also be noted that both the activated carbon catalyst as well as the silica-alumina catalyst when cracking under irradiation is high Yield proportions of hydrogen compared to conventional catalytic cracking, result.

Claims (8)

PATENT CLAIMS: 1. Radiochemical hydrocarbon conversion process, characterized in that one has a hydrocarbon in the presence of one per se known activated carbon catalyst of a strongly ionizing, mainly from gamma rays and / or exposing neutrons to existing radiation. 2. The method according to claim 1, characterized in that the radiation consists of gamma rays and the average gamma ray flux in the reaction zone is above 105 roentgen / hour. 3. The method according to claim 1 and 2, characterized in that the Radiation consists of neutrons and gamma rays and the average flux in the reaction zone from more than 105 X-rays / hour of gamma rays and from more than 10 "neutrons / cmsec. 4. The method according to claim 1 to 3, characterized in that one as a hydrocarbon, a proportion of petroleum boiling in the range between 66 and 510 ° C used. 5. The method according to claim 1 to 4, characterized in that the Activated carbon catalyst has the following properties: surface area over 50 m2 / g, Pore volume more than 0, 20 cma / g, abrasion speed less than 6a / o / hour, Bulk density more than 0.4kg / l and a total neutron absorption cross-section of carbon plus impurities of less than 75 barn total. 6. The method according to claim 1 to 5, characterized in that the Activated carbon catalyst impregnated with materials known to be catalytically effective is. 7. The method according to claim 1 to 6, characterized in that a Activated carbon catalyst is used, which is impregnated with 1 ° B and / or 6Li. 8. The method according to claim 1 to 7, characterized in that the The radiation dose acting on the petroleum content is more than 106 roentgen. Publications considered: German Patent No. 423 542.