DE936885C - Process for the transformation of gasoline - Google Patents

Description

Process for transforming gasoline The invention relates to a conversion process to improve the anti-knock value of gasoline and gasoline fractions, contain the aliphatic and cycloaliphatic hydrocarbons, such as. B. Gasoline of relatively low anti-knock value, distilled from paraffinic crude oils are, and of corresponding gasoline fractions of slightly higher octane value, like them from Naphehenian crude oils or by cracking.

It has already been suggested that the propensity for knocking be low boiling aliphatic and hydroaromatic hydrocarbons of gasoline character by reducing them to temperatures above 40 ° in the vapor phase, z. B. between 450 and 600 °, at normal or increased pressure of action of fixed catalytic converters. These catalysts fail Oxides of metals belonging to the 6th group of the periodic table, namely they consist either of such oxides alone or mixed with oxides of elements the 3rd and q .. group with or without carriers. In these known methods Hexa: hydrotoluene can thereby be converted into toluene with good yield; that it is passed in a stream of nitrogen at 45o ° over a catalyst from Molybdic acid mixed with ro% alumina. The molybdic acid goes with this one Temperature in molybdenum oxide above. A synthetic gasoline fraction is also used a boiling point between z i5 and i25 ° and a specific gravity of 0.779 from a lignite tar, obtained by destructive pressure hydrogenation, in vapor form Condition treated in a hydrogen stream, which about 4% hydrocarbons contains. _ The treatment takes place at q.50 ° in contact with a molybdic acid catalyst, which has been treated with hydrogen below 60o °. In the latter case, that has Product has a specific weight of 0.851.

It is also known to carry out a non-destructive dehydrogenation of saturated hydrocarbons in order to produce unsaturated derivatives with a corresponding number of carbon atoms by using the saturated hydrocarbons at temperatures above 40 °, preferably between about 500 and 700 °, in the vapor phase exposed to the dehydrating action of a catalyst which consists mainly of aluminum oxide and chromium oxide and preferably contains chromium oxides in an amount of 6 to 40%. The process is operated at a temperature at which no noticeable pyrolytic decomposition occurs.

In contrast to these and others. similar proposals sees the Invention the transformation of gasoline and gasoline fractions, which are aliphatic and Containing cycloaliphatic hydrocarbons by means of a method of the introduction mentioned kind before, in which however the transformation of the gasoline in contact with calcined granular or shaped catalysts is carried out, which from the refractory Carrier and up to about 1 to 2 percent by weight of oxides of the elements in the left column of the 6th group of the periodic table.

The gasolines are preferably treated with catalysts in which Production one in the subsequent calcination, optionally in the presence of gases, a compound of a metal of the left which can be converted into a highly active oxide Column of the 6th group of the periodic table by the wet on the refractories Carrier was applied, which consists of aluminum oxide or magnesium oxide and- was previously activated and preferably by chemical precipitation and then obtained subsequent calcination of aluminum or magnesium oxide hydrate or carbonate became.

When using the catalysts mentioned, it can be according to the invention the action of the catalysts on the gasoline vapors for a time of less than 20 seconds.

The catalytic masses for use in. present proceedings contain as a basic component certain refractory oxides and silicates, those of raw and fireproof in character and resistant to rough use, which - the catalyst masses with respect to the temperature during use and exposed during regeneration with air or other oxidizing gas mixtures are after they have been caused by carbonaceous deposits during a period of use have been tainted. As a granular carrier for the oxidic accelerators or secondary catalysts can e.g. B. the following are mentioned: magnesium oxide, aluminum oxide, Bauxite, bentonite clays, montmorillonite clays, diatomite, broken refractory bricks, broken silica, gläuconite (green sand).

Magnesium and aluminum oxides have a weak specificity Dehydration and reshaping effects, but are significant in this relationship of minor Improved proportions of the more catalytically active accelerators. The oxides of magnesium and aluminum can be obtained by controlled annealing from either suitable ores or minerals or from, chemically represented compounds, which on heating which provide oxides.

The mineral magnesite usually occurs in a massive or earthy form Variation and rarely in crystal form. The crystals are usually rhombohedral. In many natural magnesites, the magnesium oxide can penetrate up to a few percent Ferrooxide be replaced. The mineral is available in considerable quantities. The pure compound begins to decompose with formation of the oxide at 35o °, although the rate of decomposition practically only takes place at considerably higher rates Temperatures of around 80o to 90o ° becomes considerable. Magnesite is the dolomite, the mixed carbonate of calcium and magnesium, related. However, the latter mineral is Not as well suited for the present purpose as relatively pure magnesite. Magnesium carbonate obtained by precipitation or other chemical methods can also be used in place of the natural mineral. This allows his Use as an active ingredient in masses, which as dispersing substances such of a relatively inert character. In some cases this is the Production of catalysts with higher effectiveness and longer service life possible.

Aluminum hydroxide can be used to produce an aluminum oxide carrier by means of caustic alkalis or carbonates from a solution of aluminum salt, such as. B. of sulfate, nitrate or chloride are precipitated. The precipitation will filtered, washed and under such conditions as are used to produce a porous materials are best heated, and any coarse particles are ground to obtain a product of any desired size.

Instead of precipitated aluminum oxide, you can also use more or less use impure oxides such as those from mineral deposits, e.g. B. bauxite, are available. This has the approximate formula A1203-2 H20 and can be small quantities Iron sesquioxide contained in isomorphic mixture with aluminum oxide. Another, less common Aluminum mineral that can be used is the diaspore that approached that on Has formula A1203 * H20. Iron oxide can also contain a small portion of aluminum oxide replace in this mineral. Yet another mineral that is used as a source of aluminum oxide can serve, the dawsonite is of the formula Na Al (C 03) 2.2 Al (O H) 3. By heating This compound at a suitable temperature produces an oxide which is different Contains quantities of sodium carbonate.

The accelerators, which in minor proportions on the catalytic Carrier raw material used in accordance with the inventive concept generally include the oxides, especially the lower oxides of elements of the left row of the 6th Group of the periodic table. You can make use of the aqueous solutions of connections of these elements are represented that make up the connections absorbed by the granular carriers or by evaporation of the solvent thereon be deposited. Relatively insoluble compounds can also be found with the carriers be mixed either wet or dry. So much for the added one Accelerator is not an oxide itself, it will subsequently turn into an oxide Decomposition or other suitable conversion ° n transferred.

If chromium is used, the catalyst preferably contains negligible amounts Amounts of Cr03, Cr 02 and in particular of the sesquioxide Cr2 03, which in the reduction of the two higher oxides is obtained. Such compounds as chromic acid, H., Cr 04, which is formed by dissolving the trioxide in water, and chromium nitrate, Cr (N 03) 3, are easily soluble in water at ordinary temperatures. Your solutions can therefore be added to the various carriers which, when heated later, have a Residue of trioxide left behind, which is easy to use by means of hydrogen at 25o ° to the green sesquioxide is reducible. It usually becomes one at the beginning stage Passing through the vapors of some hydrocarbon reduces the gasoline fraction. If desired, chromium hydroxides can instead be obtained from aqueous solutions on the suspended carrier by precipitants, such as hydroxides and carbonates of the alkali metals or ammonium precipitated. As a source of chromium oxides are also Chromium ammonium sulfate, chromium chlorides, chromium fluoride, chromium potassium cyanide, chromium sulfates, Double salts of chromium and alkali metals such as chromium potassium sulfate and the alkali metal salts of the various chromic acids called.

In the case of molybdenum, the lower oxides, such as sesquioxide, are Mo203 and the dioxide Mo 0., especially as components in catalytic pulps for the present proceedings are effective. Numerous easily soluble molybdenum compounds can be used in solution to deposit molybdenum oxides on the support. As for the tungsten, the sesquioxide W203 and the dioxide W02 that are used in the Reduction of the trioxide WO, results in particularly effective catalyst components for uniform reactions according to the invention. Tungsten trioxide easily dissolves in water Ammonia solutions and can therefore conveniently be used as a starting source for tungstic acids corresponding to the various degrees of hydrogenation of the trioxide and below Formation of the trioxide can be heated. Tungstic acids can be used in place of oxides precipitated from solutions in oxides by ammonia or alkali hydroxides or carbonates will. The hydroxide is later formed into mixtures of the trioxide and the Dioxyds heated, the reduction by means of hydrogen or the gases and vapors in contact with the catalyst during normal operation of the process can be.

The most common method of adding accelerators to the preferred catalytic base material which, if carefully prepared, has a high Has adsorptive capacity, consists in that the prepared grains of approximately 1.5 to 8 meshes per centimeter in solutions of salts durahgewirbelt that the desired accelerating oxides when heated under suitable conditions deliver. In some cases, the grains can simply be soaked in moderately warm salt solutions be stirred, after which the particles of the excess solvent through Separate settling or filtering with water to remove excess Solution washed and then heated to the desired accelerating residual compound to create. With certain compounds of relatively low solubility it may be necessary to add the solution in successive proportions to the basic adsorbent material add with the interposition of heating to drive off the solvent, so that you get the desired amount of accelerator on the surface and in the pores of the catalyst base material to deposit. The ones to dry and glow after Temperatures used from the solutions depend entirely on the addition of accelerators on the individual properties of the added compound, and it can be do not specify general temperature ranges for this.

In some cases, accelerators can be made from a solution by adding them precipitants are deposited on the catalyst bodies. Usually is mechanical mixing is not to be preferred, although in some cases hydrated or easily meltable compounds these in suitable proportions of the catalyst base mixed and during the melt or flow state can be evenly distributed in it.

With regard to the relative proportions of catalyst base material and accelerator oxides In principle it can be stated that the latter is generally less than zo percent by weight of Total mass. The influence on the catalytic activity of the catalyst base material by changing the percentage cannot be calculated exactly, but rather has to be determined by experiment will. There are often good increases in catalytic effectiveness through deposition of 1% or 2% accelerator compound on the surface and in the pores of the catalyst base achieved, although the average is generally about 5%.

Catalysts of the present type can be used in any of the conventional flow processes can be used as they are customary in industrial forming plants. the The majority of today's metal forming systems work with a snake and a chamber, wherein the oil to be formed migrates through a continuous rotary element and more or is brought less rapidly to a temperature at which the cracking rate is high enough for industrial purposes. The heated products are then put into a extended reaction zone, in which the conversion reactions essentially expire to the end. The other elements adjoining this chamber or zone of the plant deal with the fractionation of the products under exaggeration light distillates, with the circulation of intermediate products and partially transformed cuts and with the removal of heavy and slightly charred Residue. In systems of this type it is more convenient to have a catalyst in the reaction chamber to use as a filler, usually in the form of shaped bodies, e.g. B. cylinders, or in the form of bodies of about 2.4 to 4 meshes per centimeter Diameter is present.

The method according to the invention can also be used in special plants be performed. So z. B. omitted the conversion chamber and the catalyst be introduced into the tubes of a continuous row of heaters. As a result of the present of the catalytic filler material, a better heat distribution is achieved, and the pipes can be made larger than usual. An operating mode be used in which the catalyst alone or with other refractory Substances are used as filling material in regenerative ovens, which alternate through the flow of flue gases is heated and then used as a means of heating and reshaping the petrol vapors are used.

Although the temperatures suitable for the process are around 40o to 75o °, the range from 500 to 600 ° is generally particularly useful. In most cases, temperatures of about 5 ° -0 ° or a little higher are preferred. Contact times less than 20 seconds have been found to be satisfactory, and those of 3 to 5 seconds is generally preferred.

Any of those made according to the method described above If desired, catalysts can be pretreated at elevated temperatures, to increase his activity. During the heat treatment, gases such as air, steam, Carbon dioxide, hydrogen, nitrogen, etc., passed over the catalyst particles. There can be no general rule for the temperature and the activation of the Specify the required length of time for the catalysts. Sometimes the best activation temperature is here higher and sometimes lower than the most favorable temperature at which it is for the Treatment of the hydrocarbons can be used. As a rule, the best Accelerator compounds, which are the lower oxides, are usually made by use of hydrogen or a reducing gas mixture before the catalyst is put into operation there is no need for a special tempering period, that for the reduction of the oxides into those of lower value would correspond to required time.

In some cases it may be most beneficial to use the catalysts by the steam mixture to be treated either alone or in admixture with one to activate the gases mentioned. It has been observed that the activation by means of hydrocarbon vapors sometimes from a small carbon deposit connected is. The a41-common 'measures briefly listed here for activation can also be used to regenerate after a certain period of use to effect.

In the following examples, which illustrate the general nature of the Using the forming process according to the invention results to be expected explain, the operation without the addition of any diluent gases to the gasoline vapors causes. Example i A catalyst was prepared by first adding chromium trioxide added to an activated clay. This was done by making a paste with a chromic acid solution, evaporation to dryness, grinding, sifting and then Reduction of the trioxide to sesquioxide by means of hydrogen at approximately 370 °. Of the finished catalyst consisted of 94 weight percent alumina, 4 weight percent Chromium sesquioxide and 2 percent by weight water.

The catalyst particles were placed in a vertical cylindrical treatment chamber brought. This moved the vapors of a Pennsylvania naphtha fraction from the initial boiling point 130 ° and final boiling point 225 'at Soo ° under atmospheric pressure with a contact time of 4 Seconds passed. The naphtha fraction obtained represented 92% of the starting material and had an octane number of 70 compared to an original value of 4o of untreated naphtha. The loss was entirely due to gas formation. That Gas had an average molecular weight of 10, which shows that it is proportionate large percentages of hydrogen were present. The activity of the catalyst remained practically constant for 5 days, followed by oxidation with air at the treatment temperature practically on its original Value was returned. In doing so, the precaution was observed that the tower was opened before the air intake was dampened.

Beisp'ie12 The general procedure in the manufacture of the catalyst consisted in ammonium molybdate dissolved in concentrated ammonia and this Solution was used as a means of bringing molybdenum oxide onto the support. 2o Parts by weight of ammonium molybdate were added to about 50 parts by weight of concentrated aqueous Dissolved ammonia. Then the solution was made by adding approximately the same amount of space Water diluted. The solution was then about 250 parts by weight activated alumina added by annealing bauxite at about 700 ° with subsequent grinding and screening to obtain a particle size of about 3 to 5 meshes each Centimeter had been made. When using the specified proportions the clay exactly absorbed the solution. The particles only became at about 100 ° Dried for two hours, then the temperature was at 350 ° for an additional 8 hours increased. After this annealing treatment, the particles were placed in a reaction chamber brought, and the molybdenum oxides were reduced in a hydrogen stream at about 50 °, whereupon they were operational.

The catalyst prepared by the process described in the preceding paragraph was used to treat a California naphtha fraction with an initial boiling point of 140 °, an end boiling point of 225 °, an octane number of 30 and a sulfur content of 0.30%. The vapors of this naphtha were passed over the catalyst at 50 ° under atmospheric pressure. The recovered naphtha has an octane number of 65 and a sulfur content of 0.07 with a yield of 93% of the starting material. The loss was due to gas formation. The gas had an average molecular weight of 12.1, indicating a significant amount of hydrogen. The catalyst retained its activity for 5 days, after which it was worked up again by simple oxidation with air at 50 °.

Claims (3)

PATENT CLAIMS: i. Process for reforming gasoline and gasoline fractions containing aliphatic and cycloaliphatic hydrocarbons in the vapor phase at over 400 °, preferably between 50o and 60o °, under about atmospheric pressure or only slightly higher pressure with catalysts made of refractory supports, in particular aluminum oxide, and Oxides of metals of the 6th group of the periodic system, in particular of chromium, are characterized in that the reshaping of the gasoline is carried out in contact with calcined granular or shaped catalysts which consist of the refractory carrier and up to about 10 percent by weight of oxides Elements of the left column consist of the 6th group of the periodic table. 2. The method according to claim i, characterized in that the gasoline vapors with catalysts are treated, during the production of which one in the subsequent calcination, possibly in the presence of gases, into a highly active oxide compound of a metal of the left column of the 6th group of the periodic table on wet Ways on the refractory support, which was made of aluminum oxide or magnesium oxide exists and has been activated beforehand and which is preferably by chemical precipitation and subsequent calcination of aluminum and magnesium oxyhydrate or carbonate was obtained. 3. The method according to claim i and 2, characterized in that the gasoline vapors of the catalyst action for less than 20 seconds be subjected. Reference documents: French patent specifications No. 8o5 69o, 8o6 847, 629 838; British Patent Nos. 445 797, 445 757.