DE3813689A1 - Process for the reaction of branched olefins with alkanols - Google Patents

Abstract

A process for the reaction of branched olefins with alkanols in the presence of hydrogen and catalytically active lamellar clays at elevated temperatures and pressure offers particular advantages, in particular in the economical respect, if instead of the hitherto customary catalyst-loaded ion exchange resins lamellar clays are used which are loaded with catalytically active amounts of hydrogenation-active metals.

Description

The invention relates to a method for implementing branched Olefins with alkanols in the presence of hydrogen and catalytically effective layer tones at elevated temperatures and pressure.

The aim of the invention is generally the production of ethers and especially the use of heterogeneous catalysts the production of ethers by reacting a branched C₄-C₇ olefins or a mixture of these olefins with one suitable alcohol.

The manufacture of ethers is for the manufacture of chemical ones Individual compounds and additives for gasoline are important. The production of methyl tert-butyl ether (MTBE) from methanol and isobutene or Hydrocarbons contained in isobutene. In this context is also the production of tert-amyl methyl ether (TAME) by the reaction of methanol with 2-methylbutene-2- (or To mention 2-methylbutene-1), which, for. B. in one C₅ / C₆ olefin mixture from a light cat cracking gasoline (LCCS) is included. One commonly mentioned in these The catalyst used is an acidic cation exchange resin, e.g. B. a strongly acidic cation exchange resin, which essentially consists of a sulfonated polystyrene resin, in particular a polystyrene matrix crosslinked with divinylbenzene with 0.5 to 20%, in particular 4 to 16%  copolymerized divinylbenzene, to the ionizable or functional sulfonic acid groups are bound. Such Resins are manufactured industrially and are sold under ver sold various trade names. Typical examples are those under the registered trademarks LEWATIT (Fa. Bayer AG) and AMBERLYST (Rohm and Haas), which act as Etherification catalysts in MTBE production known are. Furthermore, as catalysts for the production of Clays formed in layers have been described. So describe EP-A-00 31 252 and 00 31 687 processes for Production of ethers by reacting an alcohol or several with one olefin or more in the presence of one Cation-interchangeable layered clay, the cation being either is a metal or hydrogen.

A commonly used in the manufacture of ethers heterogeneous, strongly acidic catalyst problem is the formation of so-called "gums", which by dimerization or oligomerization of reactive unsaturated hydrocarbons, especially dien, which as impurities in the used hydrocarbon fractions occur will. The gum formation can lead to the formation of polymers or near the catalytic sites, the in turn to a loss of activity and in extreme cases leads to a complete deactivation of the catalyst. A The solution to this gum formation problem is that a hydrogenation component in the strongly acidic exchange resin, especially palladium, built in and with the addition of hydrogen is working. The exchange resins containing palladium can not by means of common working techniques, e.g. B. by Impregnation with a thermally decomposable palladium compound and then thermally decomposing them be produced because the exchange resins even in the elevated temperatures are unstable for thermal Decomposition of the palladium compound to palladium required are. There are therefore other measures that are required a very expensive catalyst.  

Accordingly, the invention is based on a heterogeneous acid Catalyst directed to reduced effectiveness in terms of gum formation and relatively inexpensive is in the making. The invention is further based on the Use of the catalysts mentioned in the process of directed at the beginning.

This object is achieved in that instead of the previously used acidic ion exchange resins Layered clays used with catalytically active Amounts of hydrogen-active metals are loaded.

The process of the invention is an etherification process in which the branched olefins, especially the composition C₄ to C₇, with an alcohol at elevated temperature in the presence of hydrogen and of metals with hydrogenation activity, with which load a catalytically effective form of a layered tone is to be implemented.

The layered clay catalysts to be used according to the invention are much cheaper than the corresponding acidic ones Ion exchange catalysts, since layered clays are sufficient are thermally stable to the catalysts using conventional To produce work techniques. Although all branched C₄-C₇ monoolefins could be used, it is advantageous either isobutene, which is essentially pure or used together with monoolefinic impurities can be, or a penten, e.g. B. a methyl butene, which in essentially in pure form or in a mixture with lower or higher olefins, e.g. B. butenes, including isobutene or witches, can be used.

Preferred alcohols for the process of the invention are e.g. B. Methanol, ethanol, propanols, butanols, pentanols and hexanols or similar.  

A preferred embodiment of the method of the invention relates to the reaction of isobutene with methanol for the production from MTBE. According to a further preferred embodiment a methylbutene can be converted to TAME. Preferred Sources of monoolefin reactants for use in the Methods of the invention are the refinery streams which are in the commonly referred to as LCCS (Light Cat Crack Spirit) will. These products are created during catalytic cracking heavier petroleum fractions with a boiling range of übli usually 350 to 550 ° C for lighter products. It can Crack gasoline can also be used in the splitting of Light petrol in the presence of water vapor as a by-product attack. LCCS fractions and / or steam cracked gasoline fractions, the branched C₄-C₇-, especially C₄-C₆ monoolefins can contain according to the method of the invention in a first stage can be reacted with methanol under conditions where TAME and higher ethers are formed in optimal amounts will; then again in a second stage Methanol implemented, and under conditions in which MTBE forms in optimal amounts.

The hydrogen required for the process of the invention is used in an amount sufficient to meet the requirements Suppress gum formation. The hydrogen can be pure Form or be used with the usual impurities.

A metal with hydrogenation activity on a catalytically effective form of a layered tone used. Suitable metals with a hydrogenation effect are made that of palladium, nickel, iron, rhodium and platinum Group selected; Palladium is preferred. The amount the hydrating component used depends on nature of the metal. For precious metals, e.g. B. palladium Amount preferably less than 1 wt .-%, in particular less than 0.5% by weight, preferably 0.05 to 0.5% by weight. For others Metals, e.g. B. for nickel, larger metal contents can be required to be such.  

Layer clays of natural and / or synthetic origin are suitable as catalyst supports for the process of the invention. Preferred layered clays are smectites, especially those derived from the montmorillonite, e.g. B. bentonites and fuller earths, hectorites, beidellites, vermiculites and nontronites formed group are selected. Montmorillonites are particularly preferred. In their natural state, layered clays generally have catalytically inactive interchangeable cations, e.g. B. Na⁺ and Ca ²⁺ on. In order to convert these layered clays into a catalytically active form suitable for the process of the invention, it is first necessary to use catalytically active cations, e.g. B. H⁺, Zr ⁴⁺ or Al ³⁺ to undergo an ion exchange. The cation exchange with these catalytically active cations can take place by means of conventional exchange techniques which do not significantly impair the layer structure of the clay, e.g. B. by treating the clay with an aqueous solution of a salt of the desired metal at a temperature below about 50 ° C.

The catalyst for use in the process of the invention can be suitably made by using a active form of the layered clay with a solution of a thermal decomposable and / or reducible compound of a metal impregnated with a hydrogenation effect and then the Compound thermally decomposed to form the metal and / or reduced. The impregnation can either by means of the so-called "Incipient wetness" - or the "Excess solution "technology. In the first method mentioned the activated layer tone with so little solution of the metal compound offset that practically only the pore volume with Liquid is filled, followed by the solvent Evaporation removed. The second method uses the activated one Layered clay suspended in the solution of the metal compound; then the solvent is removed by evaporation. The solution of the metal compound can be aqueous, alcoholic or be watery / alcoholic.  

Unlike the ion exchange resins, layered clays are used in the elevated temperatures that are required to maintain the thermally decomposable / reducible connections to the To decompose or reduce metals, which causes a cost cheaper catalyst can be obtained. Suitable Close thermally decomposable or reducible connections Salts of metals, especially halides and nitrates, especially the halides, one of which in turn is the Chlorides are the most beneficial. When using Palladium chloride for the impregnation must be the layer tone typically in the presence of hydrogen to a temperature of about 220 ° C to the palladium chloride reduce elemental palladium. When using other metals can have higher or lower temperatures to be required. Other commonly used work techniques can also be used to manufacture the loaded Catalysts are used.

The method of the invention is preferably used in a Temperature in the range between 40 to 120 ° C and a pressure in Range from 4 to 80 bar carried out in the liquid phase. For example, B. at a temperature of the aforementioned range of selected pressure not to work in the liquid phase to enable, the pressure is appropriately appropriate increased to allow working in the liquid phase. Otherwise, the method of the invention can also be carried out in the vapor phase.

The optimal temperatures and pressures within the aforementioned Areas depend on the nature of the reactants and the catalysts used in each case. The procedure of The invention can be carried out continuously or batchwise will; continuous operation is preferred.

The method of the invention is hereinafter referred to explained in more detail on the exemplary embodiments.

Examples Preparation of kata suitable for the process of the invention lysators Precursor of catalyst A

100 g of montmorillonite (in the H⁺-exchanged form) were in 1 l of deionized water dissolved. To the layered clay suspension an aqueous palladium chloride solution (0.83 g / 500 ml) given; the reaction mixture was rotated in vacuo evaporator evaporated to dryness. The solid received Catalyst precursor was in an oven overnight at 100 ° C dried.

Precursor to catalyst B

100 g of in the preparation of the catalyst precursor A montmorillonite used was mixed with palladium nitrate (1.30 g in 500 ml) in a similar manner as for the catalyst precursor A described, impregnated.

Precursor to catalyst C

100 g of montmorillonite (in the H⁺-exchanged form) was overnight at ambient temperature in an aqueous palladi umchloric acid solution (0.83 g in 2 l deionized water) stirred. The layered clay was washed with deionized water and suspended again in a palladium chloride solution overnight. The layer clay was deionized with 4 x 500 ml Washed water and dried in an oven at 100 ° C.

Reduction of the catalyst precursors

The catalyst precursors A to C were used to form the active form of the catalyst using the following procedure reduced:  

The catalyst precursor (60 cm³; 0.5 to 1.0 mm particles) was placed in a reactor. Hydrogen (2 l / h) became about For 1 hour at ambient temperature over the precursor headed. The temperature rose within an hour Increased 100 ° C; this temperature was maintained for 2 hours. The temperature was then raised to 220 ° C (within of about 1.5 hours); this temperature became 4 Maintain hours. The catalyst obtained was allowed to pass Night under a constant stream of hydrogen on ambient cool down temperature.

Testing the catalysts Examples 1 to 3

An etherification stream of the following composition:

Component weight%

Methanol 11.6 2-methylbutene-2 9.9 Isoprene 2.7 Raffinate II *) 63.5 Isobutene 12.4

*) The Raffinate II is the exhaust gas from a steam cracker Separation of i-butene and contains n-butane, butene-1, trans Butene-2 and cis-butene-2 as main components.

was passed together with hydrogen in a ratio corresponding to about a 2: 1 molar excess, based on diene content, into a reactor containing a fixed catalyst bed. All tests were carried out under standard conditions, ie at 75 ° C (middle of the catalyst bed), 15 bar total pressure and an LHSV of 2 h ^-1 . The products were analyzed on-line and off-line by means of packing and capillary gas chromatography. The results are shown in Table 1. As explained above, in Table 1 and thereafter the abbreviation MTBE means methyl tert-butyl ether and the abbreviation TAME means tert-amyl methyl ether.

Comparative experiment 1

The procedure of Examples 1 to 3 was followed a commercially available acidic polystyrene containing palladium / Divinylbenzene cation exchange resin instead of the Catalyst A repeated.

Table 1

Example 4

The procedure of Example 3 was repeated with the Modification that the temperature was 78 to 80 ° C. The products were analyzed by gas chromatography; the components are shown in Table 2 as% GC areas.

Comparative Example 2

The procedure of Example 4 was repeated with the Modification that no hydrogen is added to the feed has been. The results are summarized in Table 2.  

Table 2

Claims (8)

1. Process for the reaction of branched olefins with alkanols in the presence of hydrogen and catalytically active layer clays at elevated temperatures and pressures, characterized in that layer clays are used which are loaded with catalytically active amounts of hydrogenation-active metals. 2. The method according to claim 1, characterized in that the hydrogenation-active metals from that of palladium, nickel, Iron, rhodium and platinum formed group selected are. 3. The method according to claim 1 or 2, characterized in that one uses palladium-laden layer clays. 4. The method according to at least one of claims 1 to 3, characterized in that less than 1, in particular less than 0.5% by weight of palladium-loaded layer clays used.   5. The method according to at least one of claims 1 to 4, characterized in that layered clays are used which from that of synthetic and / or natural smectites, in particular montmorillonites, such as bentonites and Fuller earths, hectorites, beidellites, vermiculites and Nontronites, formed group are selected. 6. The method according to at least one of claims 1 to 5, characterized in that one loaded with palladium Montmorillonite used. 7. The method according to at least one of claims 1 to 6, characterized in that the reaction at temperatures from 40 to 120 ° C and a pressure of 4 to 80 bar carried out in the liquid phase. 8. The method according to at least one of claims 1 to 7, characterized in that catalytically active Layered clays are used, which are made from cation-exchanged Layer toning by impregnating them with thermal decomposable or reducible compounds of the hydrogenation active Metals and thermal treatment of the impregnated Layered clays are made.