DD208735A3 - METHOD AND CATALYST FOR PRODUCING HYDROCARBONS - Google Patents

Abstract

The invention relates to a process for the preparation of hydrocarbons, such as paraffins, olefins and aromatics, and hydrocarbon fractions whose boiling points are in the range of the boiling limits of gasolines, starting from methanol and / or dimethyl ether, which easily by known methods from potential Kohlenstofftraegern on synthesis gas are economically available. Methanol and / or dimethyl ether are converted at temperatures above 523K in hydrocarbons, preferably C deep 6, to C deep 10-aromatics, when a catalyst consisting of a porous silica, the by precipitation or hydrolysis of soluble silicates or silicon compounds (polymeric Silicas) which is subjected to modification with aluminum compounds, preferably with aqueous aluminum salt solutions, whereby the aluminum can enter the silicate network as a substitute for silicon or as a salt of polysilicic acids.

Description

Title of the invention

Process and catalyst for the production of hydrocarbons

Field of application of the invention

The invention relates to a process and catalyst for the production of hydrocarbons, such as paraffins, olefins and aromatics, and hydrocarbon fractions whose boiling points are in the range of the boiling limits of gasolines, starting from methanol and / or dimethyl ether, which by known methods from potential carbon carriers over Synthesis gas is readily available economically ·

Characteristic of the known technical solutions

It is known to convert methanol and / or dimethyl ether to water and a mixture of different alkanes, alkenes and aromatics at temperatures above about 533 K and total pressures of 0.05 to about 10.0 IPa on zeolitic aluminosilicates.

For this purpose it is necessary to select specific aluminosilicate zeolites according to numerous physical and chemical criteria. While the high acidity, due to the high aluminum content of some zeolites, limits their use by too rapid inactivation by coke deposition, other types of zeolites are too small or too large pores that significantly affect the selectivity of forming economically interesting hydrocarbons coke formation, not suitable for the conversion of methanol or dimethyl ether.

Bs has been found to be particularly advantageous, e.g. according to DD-AP 123 446, silica-rich crystalline aluminosilicates, preferably of the ZSM type, with the particular preference of the Z3M-5 type, for the conversion of oxygen-containing hydrocarbon compounds, preferably methanol and / or dimethyl ether, into aromatic-rich hydrocarbon fractions. Silica-rich zeolitic ZSH-5-type aluminosilicates are particularly suitable for the conversion of alcohols, it being understood that methanol has the highest commercial interest, being particularly useful in addition to catalytically active acid sites which are considered to be BRÖHSSED-type in general ie Such centers, which cause the catalytic activity of the zeolites, have uniform pore sizes in the range 0.5 "to 0, -Sna, which cause an inevitable access, for example, to exit of substrate or reaction product molecules from the pore system of the zeolite.

This on the one hand, the high selectivity of the formation of CV to C ^ hydrocarbons, preferably 'aromatics ^ - made possible in the ilethanolkonversion and on the other hand hindered the formation of high molecular weight hydrogen-poor hydrocarbons ,.the gate stages for the formation of Koksabscheidungen. In this way, catalysts resulting in shape selective conversion of e.g. Methanol su hydrocarbons with limited coke formation, which leads to an inactivation of corresponding catalysts permitted.

The silica-rich crystalline aluminosilicates having the described properties belong to the class of tectosilicates or pentasils (KOKOTAILO, G.5, Meier, WM: in: Proceedings of the Conference on the Properties and Applications of Zeolites, London: Heyden & Son, 1980). From the variety of possible structural variants ha.ben have proven to be particularly effective in methanol conversion, the channel structures with

- ^ Ä, w WW? ⁵ ^

Pore sizes around 0.6 run. Such structures include, for example, those described in Uo-PS 3,702,886 ZSr.i-5 zeolites, the crystalline silica described in DE-OS, the 5 ¹ UI-zeolites described in GB-PS 1,563,345 and DE-OS 2,830,787 described in zeolitic Lietallsilicate on.

Although prepared by different synthetic routes, the corresponding silicic acid regions are structurally analogous zeolites of the ZSM-5 type with respect to low-aluminum crystalline a-silosilicates. Since it is generally assumed that IT network aluminum atoms and the corresponding associated cations represent the active sites for catalytic reactions or hydrocarbon conversions on crystalline aluminasilicates, it was surprising that SiO ₂ rich or very little Al ₂ O. Zeolites have a high catalytic activity for the conversion of hydrocarbons or hydrocarbon derivatives, such as methanol.

Of particular economic importance in this Susöinhenhang proposed methods, according to which; for example, methanol at siliceous aluminosilicates of! type Z3M-5 or its structural analogs can be preferably converted to Aromatenim region Cr to C. _Q whose boiling points are in the boiling range of gasolines, so that on this basis, from potential Kohlenstofftragem by known Sechnologien readily available compounds, such as ethanol, hydrocarbons can be produced which are suitable for internal combustion engines.

Thus, a new process for coal-based gasoline synthesis, such as, e.g. described in DS-OS 2615150 and 262S723.

The high activity and selectivity of the 3iO _9- rich crystalline aumosilicates of the type ZSM-5 for the conversion of the most acidic compounds, which are easily produced from synthesis gas.

- * - 2 ό a υ a ι ι

Therefore, such as methanol and / or dimethyl ether, are also the basis for many proposed. Process for the preparation of olefins (see B, DS-OS 2615150), aromatics (for example, DE-OS 2321743 and DE-OS 240094-6) or other, for. B. by alkylation or isomerization reactions accessible, technically required hydrocarbons or their derivatives (eg., WP 144397) ·

In connection with the use of silicatic zeolites of the ZSM-5 type, new alternative solutions have been developed to the known processes which use carbon-containing synthesis gas methanol to develop new processes for the production of hydrocarbons, such as, for example, olefins, aromatics or even benzines , are effective in an effective way.

However, the known catalysts based on siliceous crystalline Älumosilicate have some disadvantages that affect their applicability in the above methods. These disadvantages exist mainly in the. elaborate production of particularly the silicon dioxide-rich zeolites. In general, the effort increases with increasing SiO'o proportion, so that the production of silicic acid = rich zeolites is relatively complicated. The synthesis of such zeolites is carried out in G _e genwart of sodium ions using quaternary organic nitrogen compounds or organic amines, such as n-propylamine *. In addition to the broad spectrum of organic compounds as well as different metal oxides used within the varied synthetic routes, high temperatures generally between 373 to 460 K and the application of higher pressures and longer crystallization times are required * even after the synthesis thus obtained the zeolites obtained can not yet be used as catalysts. For this purpose, the synthesized sodium form must first be converted into the H form by means of lengthy ion exchange processes with a high excess of ammonium ion and associated calcinations. These processes are energy-intensive and environmentally friendly ·

- 5 -

- 5 - ι yes υ a ζ ι

Since the zeolites are obtained after their synthesis as fine powders, a deformation with binders or their incorporation into different matrices is required in order to achieve sufficient strength for their technical use as catalysts · This causes an additional effort ·

Object of the invention

The object of the invention is the production of hydrocarbons, in particular aromatics, whose boiling points are in the range of the boiling limits of gasolines, of compounds which are readily accessible from carbon carriers via synthesis gas according to known technologies, such as, for example, methanol.

presentation; the essence of the invention

The invention is based on the object of providing a novel process and a novel catalyst for the conversion of methanol and / or dimethyl ether to hydrocarbons with the aid of catalysts whose production is simple and whose activity and selectivity for the formation of Cgbis CQ aromatics is high, to find·

This object is achieved by using as the catalyst an aluminum-modified silicic acid which is an amorphous aluminum-modified silicic acid obtained by modifying polymeric silicic acid with aluminum compounds, preferably Al (NOOo) at 303 to 373 K, preferably 363 K, during ... a period of .1 to 10 hours and subsequent calcination at 673 to 973 K is produced.

It has surprisingly been found that amorphous SiO 2 which has been modified with Al 2 O 3, the conversion of methanol and / or dimethyl ether alone or in a mixture with high activity and selectivity to water and hydrocarbons, in particular to aromatics, takes place · It is particularly surprising in that the selectivity of the catalysts used according to the invention for the aromatic fraction Cg to C ₁₀ , the boiling points of which are within the range of the boiling limits of gasolines, is high.

-J u U -Ό L · I

It is characteristic of the process according to the invention that amorphous polymeric silicas are used as catalysts for the conversion of .alpha.ethanol and / or dimethyl ether.

with specific surface areas of 100 to 500 m ~ / g and ÄlpQ -.- contents of 1 to 10 Ma. -%, Torzugsweise from 2 to 6 wt .-%, are used.

A preferred embodiment of the process according to the invention is that ethanol is converted into hydrocarbons, preferably to C 1 to C _1n aromatics, on a catalyst

ο ι u ^v

converted vd.rd, of an amorphous porous polymeric silica (silica gel) having a specific surface area of 100 to 500 m / g, preferably 200 to 450 m ^ / g, by impregnation with aqueous aluminum salt solutions, particularly preferably Aluminitunnitrat, and then calcination / at temperatures between 673 to 973 K, preferably at 773 K, for 2 to 10 hours.

The catalytic reaction for the conversion of methanol and / or dimethyl ether into water and hydrocarbons, in particular aromatics, is at temperatures between 523 to 973 K, preferably at 623 to 773 K, more preferably at 673 to 723 K, and a space velocity expressed in volumes of liquid per mole of catalyst and hour (v / vh) between 0.1 and 100, preferably at 0.3 to 4, with or without diluent, at total pressures of 0.1 to 3.0 MPa.

The catalysts of the process according to the invention are activated in an inert gas stream, preferably nitrogen, at temperatures between 673 and 773 K, preferably at 773 K, or in the methanol vapor stream, at temperatures between 523 and 723 K.

In another embodiment of the process according to the invention, the conversion of the methanol, alone or in admixture with dimethyl ether, can also be carried out as a two-stage process by dehydration in a first stage

-t- 239092

of the methanol to dimethyl ether is carried out on known catalysts or those used according to the invention and in a second stage by the process according to the invention dimethyl ether is reacted alone or in a mixture with methanol to give hydrocarbons.

It is a particularly advantageous form of the process according to the invention to use those catalysts which have been produced spherically and which have subsequently been subjected to a modification with aluminum compounds. In this way, deformation or incorporation into any matrices in the case of the catalysts used according to the invention is not required.

With the process according to the invention, it is possible to produce hydrocarbons, such as paraffins, olefins and aromatics, from methanol and / or dimethyl ether, preferably aromatic hydrocarbons in the range from Gg to C, and the unreacted starting materials methanol and / or diethyl ether of / i ed he be returned to the reaction cycle.

Depending on the reaction conditions, such as temperature, pressure and space velocity, are obtained by the novel process of methanol as paraffins with the chain length C ₁ to Cg , as olefins preferably ethene and Propenj "and as aromatics preferably those in the range Gg to G ₁₀ .

It is therefore obvious that also with feedstocks which, in addition to methanol, both lower alcohols, such as e.g. Ethanol or propanol, as well as other aliphatic oxygen-functional hydrocarbons, such as 3. Ethers, as well as lower olefins, e.g. Ethene or propene, can be prepared according to the process of the invention hydrocarbons or aromatics.

-Q

-23-

Sa is also within the scope of the method according to the invention, for. Conversion.yon methanol. And / or dimethyl ether to use aluminum-modified porous silicic acids, which with 'metal ions, such as. nickel, zinc, copper, platinum, iron, palladium, cadmium or silver, or mixtures thereof, are exchanged and / or impregnated.

The catalysts used according to the invention are characterized by a very low formation of hydrocarbon deposits over known catalysts for the conversion of methanol. Sine regeneration may be performed by known methods, e.g. by passing air or oxygen-containing gas streams at temperatures between 673 "to 873 K, preferably at 823 K.

Example 1.:

In this example, the preparation of a catalyst according to the invention is described.

Porous polymeric silicic acid (silica gel) with a spe-

2 zifischen surface of 46O m / g is stirred with a grain size of 0.3 to 0.5 nom for 6 hours with 3 η HCl at 333 K with a solid-liquid ratio of 1:10. ! laughing air drying, the porous polymeric silicic acid is stirred at 90 ⁰ C with a 1M .Aluminiumnitratlösung with a solid-Plüssigkeitsverhältnis of 1:10 for 6 hours. Subsequently, the aluminum nitrate solution is removed by decanting again and the porous polymeric silicic acid is washed several times with deionized water and dried at 383 K. The resulting porous polymeric silicic acid has an aluminum content of 2.3% by mass, based on the air-dry porous polymeric silicic acid used.

Example 2:

This example shows the preparation of a catalyst used according to the invention on the basis of an aluminum-modified porous polymeric silica.

"*> Q Π

A Dorösen polymeric silicic acid (silica gel) with a spe-

2 ^w sifischen surface of 4oO m / g was stirred with a particle size of 0.3 to 0.5 mm β hours with 3n KCl at 90 ⁰ G with a solid-liquid ratio of 1:10, after drying in air the porous silica impregnated with an aluminum nitrate solution, so that these 2 Ma. Contains ~% aluminum. It is then calcined at 773 K for 4 hours.

Example 3:

In this example, the use of the catalysts according to the invention for the conversion of methanol is demonstrated. In

3. A flow reactor was fitted with 5 cm of the porous polymeric silica each time, and after activation for one hour in nitrogen flow (1.5 l / h) at 773 K, methanol was loaded at 723 K with a load of 0.1 to 4 ₅ O v / vh were metered in. The reaction products excluding the water formed were obtained:

Catalyst according to Example 1:

Temperature in K: '673 723

Load in v / vh; 0.1

Sales in % 82.5 98.2

Product distribution in Ma .- $ 5:

Methanol 14, Q 2,4

Whore thyle ther 21.5 2.1

Total hydrocarbon 63.7 65.5

Hydrocarbons in a> based on the total carbonyl hydrogen formation:

G ₁ - Cg paraffins and olefins 7.1 16.6

Gg - C _1O aromatics 48.4. 43.1

G ₁₁ aromatics 44.6 40.0

Claims (2)

* J! <J% J Invention claims A catalyst consisting of aluminum-modified silica for the production of hydrocarbons by the conversion of methanol and / or dimethyl ether at temperatures above 523 K, characterized in that it contains amorphous aluminum-modified silica obtained by modifying polymeric silicic acid with aluminum compounds, preferably Al (MU ) ₃ , at 303 to 373 K, preferably 363 K, over a period of 1 to 10 hours and subsequent calcination at 673 to 973 K 2. Process for the preparation of hydrocarbons by the conversion of methanol and / or dimethyl , ether at temperatures above 523 K, characterized in that the catalyst used is amorphous aluminum-modified silica obtained by modifying polymeric silicic acid with aluminum compounds.