阅读说明：本技术 通过确定酸性催化的比例使丁烯低聚的方法 (Method for oligomerizing butenes by determining the proportion of acid catalysis ) 是由 F·纳多尔尼 S·派茨 G·施托赫尼奥 R·弗兰克 F·阿尔舍 C·布赖特科普夫 W·雷 于 2019-07-25 设计创作，主要内容包括：本发明提供使用含镍的硅铝酸盐催化剂使正丁烯低聚、以生产产物混合物的方法,确定并监测产物混合物中的4,4-二甲基己烯与3,4-二甲基己烯的比率。本发明进一步涉及用于确定所形成的4,4-二甲基己烯的量或所形成的3-乙基-2-甲基戊烯的量与所形成的3,4-二甲基己烯的量的比率的方法。(The present invention provides a process for oligomerizing n-butene using a nickel containing aluminosilicate catalyst to produce a product mixture, the ratio of 4, 4-dimethylhexene to 3, 4-dimethylhexene in the product mixture being determined and monitored. The invention further relates to a method for determining the amount of 4, 4-dimethylhexene formed or the ratio of the amount of 3-ethyl-2-methylpentene formed to the amount of 3, 4-dimethylhexene formed.)

1. Process for oligomerizing n-butenes using a mesoporous, nickel-containing aluminosilicate catalyst through which a reactant stream containing the n-butenes is passed to form a product mixture, characterized in that the ratio of the amount of 4, 4-dimethylhexene formed to the amount of 3, 4-dimethylhexene formed in the product mixture is monitored, the catalyst is replaced when a threshold value for the ratio (amount of 4, 4-dimethylhexene/amount of 3, 4-dimethylhexene) is exceeded,

wherein the threshold value for the ratio (amount of 4, 4-dimethylhexene/amount of 3, 4-dimethylhexene) does not exceed 0.05.

2. The process according to claim 1, wherein the process for oligomerisation is carried out at a temperature in the range of 50 ℃ to 200 ℃, preferably 60 ℃ to 130 ℃.

3. The process according to claim 1 or 2, wherein the process for oligomerisation is carried out at a pressure in the range of 10 to 70 bar, preferably 15 to 42 bar.

4. The process according to any one of claims 1 to 3, wherein the mesoporous nickel-containing aluminosilicate catalyst used in the process for oligomerization contains nickel in an amount of 0.1 to 51 wt. -%, preferably 1 to 42 wt. -%, particularly preferably 5 to 33 wt. -%, based on the total composition of the mesoporous nickel-containing aluminosilicate catalyst, calculated as nickel oxide NiO.

5. The process according to any one of claims 1 to 4, wherein the mesoporous nickel containing aluminosilicate catalyst used in the process for oligomerisation has a Si/Al ratio of 1-100, preferably 2-80, particularly preferably 3-50.

6. The process of any one of claims 1 to 5, wherein the mesoporous nickel containing aluminosilicate catalyst is free of titania and/or free of zirconia.

7. A method for determining the amount of 4, 4-dimethylhexene formed or the ratio of the amount of 3-ethyl-2-methylpentene formed to the amount of 3, 4-dimethylhexene formed, wherein the method comprises the steps of:

a) oligomerizing n-butenes using a mesoporous, nickel-containing aluminosilicate catalyst;

b) quantitatively analyzing the product stream obtained from the oligomerization to determine the amount of C8 isomer formed in the oligomerization, in particular the amount of n-octene, 3-methylheptene, 3, 4-dimethylhexene, 4-dimethylhexene, 2, 3-dimethylhexene and 3-ethyl-2-methylpentene; and

c) determining the ratio of the amount of 4, 4-dimethylhexene formed or the amount of 3-ethyl-2-methylpentene formed to the amount of 3, 4-dimethylhexene formed, wherein the ratio does not exceed 0.05.

8. The process according to claim 7, wherein the oligomerization in step a) is carried out at a temperature in the range of from 50 ℃ to 200 ℃, preferably from 60 ℃ to 130 ℃.

9. The process according to claim 7 or 8, wherein the oligomerization in step a) is carried out at a pressure of from 10 to 70 bar, preferably from 15 to 42 bar.

10. The process according to any one of claims 7 to 9, wherein the mesoporous nickel-containing aluminosilicate catalyst used in step a) contains nickel in an amount of 0.1 to 51 wt. -%, preferably 1 to 42 wt. -%, particularly preferably 5 to 33 wt. -%, based on the total composition of the mesoporous nickel-containing aluminosilicate catalyst, calculated as nickel oxide NiO.

11. The process according to any one of claims 7 to 10, wherein the mesoporous nickel-containing aluminosilicate catalyst used in the oligomerization in step a) has a Si/Al ratio of from 1 to 100, preferably from 2 to 80, particularly preferably from 3 to 50.

12. The process according to any one of claims 7 to 11, wherein the mesoporous nickel-containing aluminosilicate catalyst in step a) is free of titania and/or free of zirconia.

13. The process according to any one of claims 7 to 12, wherein the oligomerization is carried out for 1-190h ^-1Preferably 2 to 35h ^-1Particularly preferably 3 to 25h ^-1Weight Hourly Space Velocity (WHSV).

14. The method according to any one of claims 7 to 13, wherein the quantitative analysis in step b) is performed by gas chromatography.

Technical Field

The present invention relates to a process for oligomerizing n-butene using a nickel containing aluminosilicate catalyst to produce a product mixture, the ratio of 4, 4-dimethylhexene to 3, 4-dimethylhexene in the product mixture being determined and monitored. The invention further relates to a method for determining the amount of 4, 4-dimethylhexene formed or the ratio of the amount of 3-ethyl-2-methylpentene formed to the amount of 3, 4-dimethylhexene formed.

Background

Oligomerization is generally understood to mean that the unsaturated hydrocarbons react with themselves to form correspondingly longer-chain hydrocarbons, so-called oligomers. Thus, for example, an olefin having eight carbon atoms (octene) may be formed by oligomerization of two olefins having four carbon atoms (butene). The oligomerization of two molecules to each other is also referred to as dimerization.

The resulting oligomers are intermediates, for example, for the production of aldehydes, carboxylic acids and alcohols. The oligomerization of olefins is carried out either in a homogeneous phase using dissolved catalysts, or in a heterogeneous manner over solid catalysts, or on a large industrial scale using two-phase catalyst systems.

In the case of heterogeneous catalytic processes, oligomerization over acidic oligomerization catalysts has long been known. Commercially available systems include supported acidic catalysts such as zeolites or phosphoric acid. Here a more or less branched isomeric mixture of olefins is obtained. The name acidic catalysis or acidic catalyst Bronsted acidity (B) acidity), i.e. the catalyst provides catalytically active protons. In the art, frequently used for the non-acidic heterogeneously catalyzed oligomerization of olefins with high dimer selectivity are nickel compounds on support materials, where the nickel does not provide a proton but acts as an electron pair acceptor (Lewis acid). Thus, WO95/14647a1 describes a nickel catalyst for the oligomerization of olefins, which comprises a support material consisting of: titanium oxide and/or zirconium oxide, silicon oxide and optionally aluminium oxide. At this pointOligomerization of mixtures of linear butenes to C over these catalysts ₈Olefin, selectivity less than 75%. It is believed that the catalytic activity of heterogeneous nickel-based catalysts for oligomerizing olefins is based on the interaction between nickel cations and surface aluminum atoms.

In the case of oligomerization, there are various mechanisms by which oligomerization can be carried out. These include acidic catalysis, in which olefins form carbenium ions with the acid center of the catalyst, which can react with the double bonds of other olefins to form new C — C bonds. Since the carbenium ion is best stabilized at the highest degree of branching of the cation, highly branched oligomers are formed that are almost exclusively relevant for the production of fuels. There is a need in the industry for oligomers, particularly with relatively high linearity, to be further processed to provide chemical end products such as plasticizers or surfactants. An additional mechanism is a coordination mechanism in which the first olefin is coordinately bound to the catalyst. Additional olefins may become attached thereto and result in the formation of new C-C bonds, resulting in the formation of oligomers. The products of this mechanism are generally less highly branched.

There is a continuing need to develop novel process methods that can result in improved conversion and/or selectivity when used in the oligomerization of olefins to provide linear products, as compared to known oligomerization methods. It is therefore an object of the present invention to provide an oligomerization process that makes it possible to achieve higher selectivity and higher conversion to a higher linear product using oligomerization that is monitored using certain product isomers.

It is a further object of the present invention to be able to quantify the degree of saturation of the acid centers of the catalyst with nickel, thereby enabling an improved prediction of the suitability of the catalyst for oligomerization on a large industrial scale. Other objects of the invention are to be able to interpret the catalytic data in order to identify the course of formation of the catalyst and the deactivation of specific catalytic centers during the reaction. Since oligomerization is carried out as a continuous operation at elevated pressure, extraction of catalyst samples during operation is difficult, if not impossible. Therefore, in order to anticipate further run times and to evaluate the desired product spectrum (spectrum), it is important to be able to use the product formed to determine the state of the catalyst.

The underlying object of the invention is achieved by a method for oligomerization according to claim 1 and a method for determining saturation according to claim 7. Preferred embodiments are specified in the dependent claims.

Disclosure of Invention

The process according to the invention is a process for the oligomerization of n-butene using a mesoporous nickel-containing aluminosilicate catalyst over which a reactant stream containing n-butene is passed to form a product mixture, characterized in that the ratio of the amount of 4, 4-dimethylhexene formed to the amount of 3, 4-dimethylhexene formed in the product mixture is monitored and the catalyst is replaced when a threshold value for the ratio (amount of 4, 4-dimethylhexene/amount of 3, 4-dimethylhexene) is exceeded, wherein the threshold value for the ratio (amount of 4, 4-dimethylhexene/amount of 3, 4-dimethylhexene) is not more than 0.05, preferably not more than 0.01, particularly preferably not more than 0.005.

Determining the ratio comprises first determining the amount of the individual isomers, preferably by gas chromatography, and determining the ratio from said amounts. In order to achieve better separation efficiency, the sample to be analyzed (product mixture) can be hydrogenated over a heterogeneous Pd-containing catalyst with hydrogen as carrier gas in the liner before reaching the separation column. The alkanes thus obtained are more easily distinguishable than the C8 alkene isomers formed in the oligomerization.

The ratio (amount of 4, 4-dimethylhexene/amount of 3, 4-dimethylhexene) can be determined continuously, i.e. without interruption during the course of the run, or discontinuously, i.e. by periodic withdrawal of a sample of the product mixture from the process during operation. It is preferred to determine the ratio (amount of 4, 4-dimethylhexene/amount of 3, 4-dimethylhexene) discontinuously by taking samples from the product mixture at regular intervals. The interval between regular sample draws is freely selectable and depends on the device being operated. In the case of discontinuous determination of the ratio, the intervals between the sample withdrawals can in principle be carried out at intervals of 1 to 59 minutes, 1 to 23 hours, 1 to 6 days or 1 to 20 weeks. The intervals may also vary, i.e. the intervals may be longer, for example after installation of fresh catalyst, and become shorter over time.

It has been found that, surprisingly, monitoring the ratio of 4, 4-dimethylhexene to 3, 4-dimethylhexene makes it possible, by using this monitoring in the oligomerization process according to the invention, to achieve particularly good product quality and higher conversion to linear products and/or higher selectivity. The smaller this ratio, the lower the proportion of acid catalysis in the oligomerization and thus the lower the amount of highly branched oligomers formed. However, if there is an increase in the ratio of 4, 4-dimethylhexene to 3, 4-dimethylhexene, formation has occurred on the surface of the catalyst. This allows the average degree of branching that the oligomers formed will have to be determined for further operations. If the ratio exceeds a certain threshold during the process, the catalyst must be replaced. Thus, a high linearity of the almost homogeneously formed oligomers can be achieved, since by establishing a suitable threshold for the ratio, the process can be interrupted early and the catalyst replaced before even a relatively large amount of branched by-products is formed.

If the catalyst needs to be replaced due to exceeding the threshold, the used catalyst may be replaced with fresh catalyst. Depending on the device configuration, the replacement may be performed in a manner known to those skilled in the art. The fresh catalyst may be a freshly produced catalyst or a used but regenerated catalyst.

The reactant stream containing n-butenes can also be a stream of pure butenes, although this is hardly commercially feasible. Technical mixtures containing n-butenes which can be used as reactant streams are light petroleum fractions from refineries, C from FC crackers or steam crackers ₄Fractions, mixtures from Fischer-Tropsch synthesis, mixtures from butane dehydrogenation and mixtures formed by metathesis or from other industrial processes. Mixtures of n-butenes suitable for the process according to the invention can be obtained, for example, from C of a steam cracker ₄Obtained in fractions. Here in a first step toAnd removing butadiene. This can be achieved by extraction or extractive distillation of butadiene or by selective hydrogenation thereof. In both cases, C containing almost no butadiene was obtained ₄The fraction, i.e. raffinate l. In a second step, from C ₄Isobutylene is removed from the stream, for example, by producing methyl tert-butyl ether (MTBE). Other options include reaction of isobutene from raffinate I with water to provide tert-butanol, or acid catalyzed oligomerization of isobutene to provide diisobutylene. If desired, C which is now virtually free of isobutene ₄The fraction (raffinate II) contains n-butenes and possibly butanes.

In a preferred embodiment, raffinate I (butadiene free C from steam cracker) ₄Distillate fraction) or raffinate II (a butadiene-free and isobutylene-free C4 fraction from a steam cracker) was supplied to the process as a reactant stream.

A further option for producing suitable olefin mixtures is the hydroisomerization of raffinate I, raffinate II or hydrocarbon mixtures of similar composition in a reaction column. This makes it possible in particular to provide mixtures consisting of 2-butene, a small proportion of 1-butene and possibly n-butane and isobutane and isobutene.

Depending on the source and treatment of the reactant stream, compounds comprising heteroatoms, particularly nitrogen-, sulfur-and/or oxygen-containing compounds, may be present in the stream.

The oligomerization process according to the invention is preferably carried out at a temperature in the range from 50 ℃ to 200 ℃, preferably in the range from 60 ℃ to 180 ℃, particularly preferably in the range from 60 ℃ to 130 ℃. The pressure in the process according to the invention is preferably in the range from 10 to 70 bar, particularly preferably in the range from 15 to 42 bar.

In other preferred embodiments, the reactants are present in the liquid phase in the process according to the invention. If the oligomerization is to be carried out in the liquid phase, the parameters pressure and temperature must be determined for this purpose such that the reactants are in the liquid phase.

In the process for oligomerization according to the invention, the weight-based space velocity (mass of reaction per unit time per unit mass of catalyst; Weight Hourly Space Velocity (WHSV)) is preferably in the range of per gCatalyst and 1g of reactant per hour (═ 1 h) ^-1) To 190h ^-1Preferably in the range of 2-35h ^-1Particularly preferably in the range of 3 to 25 hours ^-1Within the range of (1).

The oligomerization catalyst used according to the invention comprises at least nickel oxide and aluminosilicate as support material, preferably amorphous aluminosilicate. In the context of the present invention, "amorphous" is understood to mean the nature of a solid, which results from the fact that said solid does not have a crystalline structure, i.e. does not have long-range order. However, in the context of the present invention, the case where the amorphous silica-alumina support material has small crystalline domains cannot be excluded. The amorphous silica-alumina support material is not a crystalline material, e.g., is not a zeolitic material.

The nickel-containing aluminosilicate catalyst used in the process according to the invention is mesoporous, i.e. comprises at least mesopores. The mean pore diameter of the aluminosilicate catalyst used is preferably at least 0.7 nm. The mean pore diameter can be determined by mercury porosimetry in accordance with DIN 66133(1993-06 edition).

The nickel-containing aluminosilicate catalyst according to the invention preferably comprises nickel in an amount of from 0.1 to 51% by weight, preferably from 1 to 42% by weight, particularly preferably from 5 to 33% by weight, based on the total composition of the mesoporous nickel-containing aluminosilicate catalyst. In a particularly preferred embodiment of the present invention, the oligomerization catalyst is substantially free of titanium dioxide and/or zirconium dioxide, and the oligomerization catalyst comprises in particular less than 0.5% by weight, preferably less than 0.1% by weight, particularly preferably less than 0.01% by weight, of titanium dioxide and/or zirconium dioxide in its total composition.

According to the present invention, the nickel-containing aluminosilicate catalyst may have a molecular weight of 150-700m ²G, preferably 190- ²Per g, particularly preferably 220-550m ²Specific surface area in g (calculated according to BET). The BET surface area is measured by physical adsorption of nitrogen according to DIN ISO 9277(2014-01 edition).

In other preferred embodiments, the nickel-containing aluminosilicate catalyst has a silicon to aluminum ratio (Si/Al) of from 1 to 100, preferably from 2 to 80, particularly preferably from 3 to 50.

Reactors which may be used and which are suitable for carrying out the process according to the invention include reactors known to the person skilled in the art in which the oligomerization can be carried out continuously or discontinuously. In a preferred embodiment, a fixed bed reactor or a slurry reactor, operating continuously or discontinuously, is used for carrying out the oligomerization process according to the invention. The process is carried out in particular under heterogeneous catalysis.

In a preferred embodiment, the degree of dimerization (also referred to as "percent selectivity based on dimerization") of the product/product stream obtained from the conversion reactant-based oligomerization is at least 60%, more preferably at least 75%, and particularly preferably at least 80%.

The linearity of the formed oligomeric product/dimer is described by the ISO index and represents the value of the average number of methyl branches in the dimer. For example (for butene as reactant) for ISO index of C8 fraction, n-octene contributes 0, methylheptene 1 and dimethylhexene 2. The lower the ISO index, the more linear the conformation of the molecules in each fraction. The ISO index is calculated by the following formula:

thus, a dimer mixture with an ISO index of 1.0 has on average exactly 1 methyl branch per dimer molecule.

The ISO index of the product from the oligomerization process according to the invention is preferably from 0.8 to 1.2, more preferably from 0.8 to 1.15.

The oligomers produced by the process according to the invention are used in particular for the production of aldehydes, alcohols and carboxylic acids. Thus, for example, a dimer of linear butenes (dimerizate) provides a mixture of nonanals by hydroformylation. This provides either the corresponding carboxylic acid by oxidation or C by hydrogenation ₉An alcohol mixture. C ₉The acid mixture can be used to produce lubricants or desiccants. C ₉The alcohol mixture is a precursor for the production of plasticizers, in particular dinonyl phthalate or DINCH.

The present invention still further provides a method for determining the amount of 4, 4-dimethylhexene formed or the ratio of the amount of 3-ethyl-2-methylpentene formed to the amount of 3, 4-dimethylhexene formed, wherein the method comprises the steps of:

a) oligomerizing n-butenes using a mesoporous, nickel-containing aluminosilicate catalyst;

b) quantitatively analyzing the product stream obtained from the oligomerization to determine the amount of C8 isomer formed in the oligomerization, in particular the amount of n-octene, 3-methylheptene, 3, 4-dimethylhexene, 4-dimethylhexene, 2, 3-dimethylhexene and 3-ethyl-2-methylpentene; and

c) determining the ratio of the amount of 4, 4-dimethylhexene formed or the amount of 3-ethyl-2-methylpentene formed to the amount of 3, 4-dimethylhexene formed, wherein the ratio is not more than 0.05, preferably not more than 0.01, particularly preferably not more than 0.005.

The oligomerization in step a) is preferably carried out at a temperature in the range from 50 ℃ to 200 ℃, preferably in the range from 60 ℃ to 180 ℃, particularly preferably in the range from 60 ℃ to 130 ℃. The pressure in the oligomerization in step a) is preferably in the range from 10 to 70 bar, particularly preferably in the range from 15 to 42 bar.

In other preferred embodiments, in step a) of the determination method according to the invention, the reactants are in the liquid phase and the oligomerization is carried out in said liquid phase. If the oligomerization is to be carried out in the liquid phase, the parameters pressure and temperature must be determined for this purpose such that the reactants are in the liquid phase.

In step a) of the determination method according to the invention, the weight-based space velocity (mass of reaction substance per unit time per unit mass of catalyst; weight Hourly Space Velocity (WHSV)) is preferably at 1g of reactants per g of catalyst and per hour (═ 1 h) ^-1) To 190h ^-1Preferably 2 to 35h ^-1Particularly preferably 3 to 25h ^-1Within the range.

The oligomerization catalyst of the invention used for the oligomerization in step a) of the defined process comprises at least nickel oxide and aluminosilicate as support material, preferably amorphous aluminosilicate. In the context of the present invention, "amorphous" is understood to mean the nature of a solid, which results from the fact that said solid does not have a crystalline structure, i.e. does not have long-range order. However, in the context of the present invention, the case of amorphous silica-alumina support materials with small crystalline domains cannot be excluded. The amorphous silica-alumina support material is not a crystalline material, e.g., is not a zeolitic material.

The nickel-containing aluminosilicate used in step a) of the process according to the invention is mesoporous, i.e. comprises at least mesopores. The mean pore diameter of the aluminosilicate catalyst used is preferably at least 0.7 nm. The mean pore diameter can be determined by mercury porosimetry in accordance with DIN 66133(1993-06 edition).

The nickel-containing aluminosilicate catalyst of the invention used for the oligomerization in step a) preferably comprises nickel in an amount of from 0.1 to 51% by weight, preferably from 1 to 42% by weight, particularly preferably from 5 to 33% by weight, based on the total composition of the mesoporous nickel-containing aluminosilicate catalyst. In a particularly preferred embodiment of the present invention, the oligomerization catalyst in step a) is substantially free of titanium dioxide and/or zirconium dioxide, and in particular comprises less than 0.5% by weight, preferably less than 0.1% by weight, particularly preferably less than 0.01% by weight, of titanium dioxide and/or zirconium dioxide in its total composition.

Nickel-containing aluminosilicate catalysts for determining saturation can be produced in particular by impregnation of the aluminosilicate with a solution containing a nickel salt or by coprecipitation from a single solution. In both cases, the nickel-containing aluminosilicate catalyst is subsequently calcined in an air stream or a nitrogen stream or a mixture of both at a temperature of at least 450 ℃.

According to the invention, the oligomeric nickel-containing aluminosilicate catalyst used in step a) may have a particle size of 150-700m ²G, preferably 190- ²Per g, particularly preferably 220-550m ²Specific surface area in g (calculated according to BET). BET surface area was measured by nitrogen physisorption according to DINISO 9277(2014-01 edition).

In other preferred embodiments, the oligomeric nickel-containing aluminosilicate catalyst used in step a) has a silicon to aluminum ratio (Si/Al) of from 1 to 100, preferably from 2 to 80, particularly preferably from 3 to 50.

Reactors which may be used and which are suitable for carrying out the determination process according to the invention include reactors known to the person skilled in the art in which the oligomerization can be carried out continuously or discontinuously. In a preferred embodiment, a fixed bed reactor or a slurry reactor, operating continuously or discontinuously, is used for carrying out the determination process according to the invention. The process is carried out in particular under heterogeneous catalysis.

After the oligomerization in step a), the composition of the resulting product/resulting product stream, in particular n-octene, 3-methylheptene, 3, 4-dimethylhexene, 4-dimethylhexene, 2, 3-dimethylhexene and 3-ethyl-2-methylpentene, is quantitatively analyzed. This can be achieved using gas chromatography methods known to those skilled in the art. Other methods known to those skilled in the art for structural identification of eluted hydrocarbons, such as IR spectroscopy or other spectroscopic methods, can likewise be used to determine the amount of individual isomers.

The product/product stream from step a) can be hydrogenated in step b) before it is sent to quantitative analysis, in particular gas chromatography, in order to obtain better separation efficiency in the analysis by gas chromatography. This can be achieved in particular using palladium-containing catalysts. The hydrogenation can in particular also be carried out using a gas chromatograph in the form of a hydrogenolysis gas chromatograph, in particular using hydrogen as carrier gas. Hydrogenation of the injected sample greatly reduces the number of isomers to be determined. The double bond isomers are no longer distinguished here, only the backbone isomers are identified. This information is sufficient to determine the average degree of branching of the product and to determine the ratio of 4, 4-dimethylhexene to 3, 4-dimethylhexene. The injected samples were separated by means of a commercially available non-polar column. The temperature program is optimized such that an effective baseline separation of octene backbone isomers is achieved. The detection is performed by a flame ionization detector (FID for short). The assignment of isomers (assignment) can be achieved by the residence time of the respective pure substances under the same measurement conditions and by using a mass spectrometer as detector.

When changes in the oligomerization catalyst are to be monitored by the method according to the invention, the determination method should be calibrated beforehand. The catalyst used must be an aluminosilicate containing no nickel to determine how high the ratio of the amount of 4, 4-dimethylhexene formed or the amount of 3-ethyl-2-methylpentene formed to the amount of 3, 4-dimethylhexene formed is when no nickel is present (zero value) and the oligomerization is carried out virtually completely by acid catalysis. The calibration process carried out before the inventive method for determining saturation comprises in particular the following steps:

aa) oligomerization of n-butenes using a mesoporous, nickel-free aluminosilicate catalyst at different temperatures and/or loadings (different WHSV);

bb) quantitative analysis of the product stream obtained from the oligomerization to determine the amount of the C8 isomer formed in the oligomerization, in particular the amount of n-octene, 3-methylheptene, 3, 4-dimethylhexene, 4-dimethylhexene, 2, 3-dimethylhexene and 3-ethyl-2-methylpentene; and

cc) determining the amount of 4, 4-dimethylhexene formed or the ratio of the amount of 3-ethyl-2-methylpentene formed to the amount of 3, 4-dimethylhexene formed.

Optionally, step aa) or step a), i.e. the oligomerization of the method of determination of the invention, can be carried out by adding oxygen-, sulfur-and/or nitrogen-containing compounds, such as, for example, water, carbon monoxide, carbon dioxide, alkylamines having 1 to 5 carbon atoms, aldehydes and ketones having 1 to 6 carbon atoms, alcohols having 1 to 6 carbon atoms, carboxylic acids and ethers and esters having 1 to 8 carbon atoms, and sulfides, disulfides, thioethers and/or mercaptans having 1 to 4 carbon atoms. The addition should not exceed 10ppmw based on the elements O, S and/or N present in the compound. This enables the identification of the formation and deactivation processes caused by oxygen-, sulphur-and/or nitrogen-containing compounds or otherwise caused by sintering of nickel species due to long process run times (uptime), based on the development of product pedigrees, in particular the ratio of 4, 4-dimethylhexene to 3, 4-dimethylhexene.

These data allow prediction of oligomerization in continuous operation. Depending on the source of the reactant stream, heteroatom-containing compounds which may be present in very small amounts in the industrial reactant stream lead to changes in the catalyst during the reaction, which can be better predicted by the determination process according to the invention.

Detailed Description