Method for selective dehydrocyclization and aromatization of SAF-ranged hydrocarbons into aromatic compounds having the same total carbon number

Abstract

The present invention relates to a method for selective dehydrocyclization and aromatization of linear or branched hydrocarbons in the SAF range into aromatics in the SAF range.

Description

[0001] Method for selective dehydrocyclization and aromatization of SAF- ranged hydrocarbons into aromatic compounds having the same total carbon number

[0002] The present invention relates to a method for selective dehydrocyclization and aromatization of linear or branched hydrocarbons in the SAF range into aromatics in the SAF range.

[0003] The industries in the transportation sector are faced with increasing requirements to deploy sustainable fuels. With respect to the aviation industry, these are called sustainable aviation fuels (SAF). In order to meet the respective targets, new solutions are needed.

[0004] Currently, the industry specifies aromatic compounds, or shortly aromatics, as a mandatory constituent of aviation fuel due to their sealing-swelling properties, required for the proper function of the sealings of jet engines. However, the combustion of aromatic compounds has been identified as the main cause for the contrails of planes and their very relevant negative contribution to climate change. Therefore, one of the industry's longer-term goals is to replace these aromatic compounds by SAF-ranged cycloparaffins, which are cyclic alkanes having a total number of carbon atoms per molecule (carbon count) which basically ranges from Cs to Cis. Cycloparaffins replacing the aromatics are expected to exhibit comparable sealing-swelling properties, while their combustion is much cleaner than the combustion of aromatics.

[0005] Generally, cycloparaffins can be obtained from linear alkanes, also called paraffins, and alkenes, also called olefins in the petrochemical industry, by thermochemical transformation. This transformation involves successive dehydrogenation and ring-closing reaction steps, which can be catalyzed by metals that are active in the hydrogenation and / or dehydrogenation of hydrocarbons or by acid sites.

[0006] One possible pathway to produce cycloparaffins from linear olefins and / or alkanes comprises the dehydrocyclization of linear (or branched) olefins and / or alkanes leading (mostly) to cyclic aromatic compounds, followed by hydrogenation of the aromatic compounds to yield cycloparaffins. The present invention focusses on the first of these two reaction steps.

[0007] Dehydrocyclization is defined as the action of closing the carbon ring combined with dehydrogenation. The formation of the aromatic compounds according to the first reaction step described above involves further dehydrogenation steps allowing for full conjugations of the forming double bonds. Because the invention is aimed at the production of aromatic compounds, in the context of this application dehydrocyclization and aromatization are usually named together.

[0008] Current dehydrocyclization technologies focus on the production of benzene, toluene and xylene (BTX) for applications in fuels and petrochemistry. The carbon count of these products reaches from Ce for benzene, over C7 for toluene to Cs for xylene. The known dehydrocyclizations for BTX formation are performed with the help of a catalytic reforming process unit.

[0009] The dehydrocyclization and aromatization of linear or branched olefins and / or alkanes to BTX products can be performed by using catalytically active acid sites for the equilibrium production of BTX products or by using metals that are catalytically active in hydrogenation or dehydrogenation reactions for the selective dehydrocyclization and aromatization reaction. The combined use of catalytically active acid sites and metal sites (bifunctional catalysis) is also known in the prior art. The scientific article "Dehydrocyclization of alkanes over zeolite-supported metal catalysts: monofunctional or bifunctional route" by Meriaudeau & Naccache, for example, reviews the aromatization of BTX products. It discusses in detail the conversion of n-hexane (Ce), n-heptane (C7), and n-octane (Cs) over supported platinum (Pt) catalysts, particularly over Pt-zeolite catalysts.

[0010] The aromatization of lighter hydrocarbons having a carbon count of C2 to Cs carbon atoms is also well known in the prior art. There are commercially available aromatization technologies, for example M2-forming from Mobil, Cyclar from BP- UOP, and Aroforming from IFP-Saluted.

[0011] The dehydrocyclization and aromatization of hydrocarbons with carbon chain lengths exceeding a carbon count of Cs, however, has not been reported yet or established with satisfying results. Yet, a total carbon count spreading from Cs to Cis, preferably from C9 to C17, and more preferably from C10 to Ci6 is required for achieving the chemical and physical properties prescribed for aviation fuel - in particular the boiling point distribution. Thus, only aromatics in the SAF-range, i.e. with a carbon count between Cs and Cis, preferably between C9 - C17, and more preferably between C10 and Ci6, are interesting for direct use as a constituent of SAF, or, preferably, to produce cycloalkanes replacing the aromatics in the SAF and thus leading to an aromatics-free aviation fuel.

[0012] The object of the present invention is therefore to provide a method for the selective dehydrocyclization and aromatization of linear or branched hydrocarbons in the SAF range (i.e. having a number CE of carbon atoms, wherein E = 8 - 18, preferably E = 9 - 17, more preferably E = 10 - 16) into aromatic compounds in the SAF range (i.e. having a number CP of carbon atoms, wherein P = 8 - 18, preferably P = 9 - 17, more preferably P = 10 - 16).

[0013] Said object is solved by a method according to claim 1.

[0014] According to the present invention, a method for selective dehydrocyclization and aromatization of linear or branched hydrocarbons in the SAF range into aromatics in the SAF range is provided, wherein the hydrocarbons comprise alkanes, olefins or mixtures thereof, wherein the hydrocarbons have a number CE of carbon atoms, wherein E = 8 - 18, preferably E = 9 - 17, more preferably E = 10 - 16, wherein the aromatics have a number CP of carbon atoms, wherein P = 8 - 18, preferably P = 9 - 17, more preferably P = 10 - 16, and wherein the dehydrocyclization and aromatization is catalyzed by use of a supported metal catalyst comprising a support and a metal active for hydrogenation or dehydrogenation of hydrocarbons which is loaded to the support.

[0015] In the context of the present invention, the terms "comprise" or "comprising" refer to a meaning that a given subject-matter comprises a given feature (e.g. feature A). However, the terms "comprise" or "comprising" do not express that the given subject-matter solely consists of the given feature (e.g. feature A). Much more, the terms "comprise" or "comprising" are associated with a meaning that the given subject-matter may - in addition to the given feature (e.g. feature A) - comprise further features (e.g. features B and C).

[0016] The term "hydrocarbon" refers to an organic compound consisting entirely of hydrogen and carbon. In the process according to the invention, only linear and / or branched hydrocarbons are used as reaction educts, also called reaction feed.

[0017] Additionally, the term "alkane" as used in the present invention refers to acyclic (i.e. linear or branched) saturated hydrocarbons, wherein between all adjacent carbon atoms only single bonds occur. The term "paraffin" or "paraffinic" is used as a synonym.

[0018] Furthermore, the term "olefin" or "olefinic" as used in the present invention refers to an unsaturated hydrocarbon, comprising one or more double bonds between adjacent carbon atoms, wherein these double bonds may be internal or in the terminal position. The term "alkene" is used as a synonym. When mentioned in connection with the reaction educt, also called reaction feed, the terms "olefin" or "alkene" refer to acyclic hydrocarbons (i.e. linear or branched).

[0019] According to the present invention, the reaction educts are turned into aromatics. The synonymous terms "aromatic compounds" or "aromatics" as used in the present invention refer to conjugated cyclic compounds.

[0020] The present invention focusses on hydrocarbons in the SAF range, which are hydrocarbons having a total number CE of carbon atoms, wherein E = 8 - 18, preferably E = 9 - 17, more preferably E = 10 - 16. Thus, the linear or branched hydrocarbons comprising the reaction feed each comprise between 8 and 18, preferably between 9 and 17 and more preferably between 10 and 16 carbon atoms per molecule. In particular the reaction feed may comprise all paraffinic and olefinic isomers of hydrocarbon molecules containing 8 to 18, preferably 9 to 17 and more preferably 10 to 16 carbon atoms per molecule. Examples of reaction educts according to the present invention include octene, octane, nonene, nonane, decene, decane, undecene, undecane, dodecene, dodecane, tridecene, tridecane, tetradecene, tetradecane, pentadecene, pentadecane, hexadecene, hexadecane, heptadecene, heptadecane, octadecene and octadecane as well as their isomers. For octene, for example, these isomers include 2-methylheptene, 3- methylheptene, 4-methylheptene, 2,2-dimethylhexene, 2,3-dimethylhexene, 2,4- dimethylhexene, 2,5-dimethylhexene, 3,3-dimethylhexene, 3,4-dimethylhexene, 3-ethylhexene, 2,2,3-trimethylpentene, 2,2,4-trimethylpentene, 2,3,3- trimethylpentene, 2,3,4-trimethylpentene, 3-ethyl-2-methylpentene, 3-ethyl-3- methylpentene, and 2,2,3,3-tetramethylbutene. For octane, as another example, these isomers include 2-methylheptane, 3-methylheptane, 4-methylheptane, 2,2- dimethylhexane, 2,3-dimethylhexane, 2,4-dimethylhexane, 2,5-dimethylhexane,

[0021] 3.3-dimethylhexane, 3,4-dimethylhexane, 3-ethylhexane, 2,2,3- trimethylpentane, 2,2,4-trimethylpentane, 2,3,3-trimethylpentane, 2,3,4- trimethylpentane, 3-ethyl-2-methylpentane, 3-ethyl-3-methylpentane, and

[0022] 2.2.3.3-tetramethylbutane.

[0023] According to the present invention, the reaction product is an aromatic compound having a total number CP of carbon atoms, wherein P = 8 - 18, preferably P = 9 - 17, more preferably P = 10 - 16. This means that the reaction product comprises an equal number of carbon atoms per molecule as the reaction educt. In other words, employing the method according to the invention is suitable to convert linear or branched hydrocarbons to aromatic compounds having the same carbon count. Additionally, aromatic compounds may be formed, having an increased or decreased number of carbon atoms per molecule compared to the educt molecule. Additionally, olefins, polyolefins, cycloolefins, paraffins, cycloparaffins, polyaromatics bicyclic olefins may form as by-products.

[0024] A chemical conversion without a change in the carbon count as described in the present invention may occur via dehydrocyclization. The term "dehydrocyclization" as used in the present invention refers to the chemical conversion of linear or branched hydrocarbons (i.e. alkanes or olefins in this context) into cyclic compounds while splitting off (molecular) hydrogen gas (H2). Further dehydrogenation steps then lead to the formation of aromatic compounds, which is referred to "aromatization" in the present invention.

[0025] The dehydrocyclization (and aromatization) according to the present invention is catalyzed by a dehydrocyclization catalyst. According to the invention, the catalyst used for dehydrocyclization (and aromatization) is a supported metal catalyst. These catalysts comprise a metal which is active for the hydrogenation and dehydrogenation of hydrocarbons. The bulk metal, however, usually shows no or little catalytic activity. In order to increase the metal's activity for reactions, it needs to be prepared in small particles, whereby the particle size is a crucial parameter influencing the activity, selectivity and lifetime of the catalyst. Further, the small metal particles need to be loaded to a support. These supports usually have a high-surface area, which facilitates the homogenous distribution or dispersion of the metal particles deposited on the support and influences the particle size. The selection of a suitable support and / or preparation method for the catalyst is very important, as the textural and physicochemical properties of the support have a great impact on the formation of metal particles and, consequently, the catalyst's performances.

[0026] Surprisingly, supported metal catalysts according to the present invention are able to catalyze the dehydrocyclization and aromatization of hydrocarbons in the SAF range (i.e. having mostly a higher carbon count compared to BTX), without changing the total number CE of carbon atoms in each molecule.

[0027] According to an embodiment of the invention, the dehydrocyclization is performed at a reaction temperature of 400°C to 600°C, preferably 450°C to 550°C, and at pressure of 0.1-10 bara, preferably between 1-3 bara, more preferably at atmospheric pressure. These reaction conditions are suitable to yield aromatic compounds.

[0028] According to another embodiment of the invention, the support is non-acidic. It was found that a non-acidic support favours the formation of SAF-ranged aromatic compounds. In contrast, the use of an acidic support in aromatization reaction conditions can lead to significant cracking and - independent of the fed hydrocarbon - to the formation of BTX products, which have a lower carbon count. Therefore, the support preferably is non-acidic, at least at the time when the synthesized catalyst is used for dehydrocyclization and aromatization. In case the support comprises silicium (Si) and aluminium (Al), the acidity of the support can, for example, be tuned using different Si / AI ratios. Alternatively, aluminium can be replaced with Boron (B) or Germanium (Ge), for instance. According to a further embodiment of the invention, the support is mesoporous, microporous or nonporous. Mesoporous in the context of this application means that the support contains pores with a diameter in the range of 2-50 nm. Microporous in the context of this application means that the support contains pores with a diameter below 2 nm. Nonporous in the context of this application means that the support has neither mesopores nor micropores. It has, thus, no pores. Preferably, the support is mesoporous, because the pores increase the surface area of the support, which leads to a better (i.e. more homogenous) metal distribution or dispersion on the support and, as a consequence, to a higher active catalyst. Moreover, mesopores help the linear or branched hydrocarbons of the reaction feed to adopt a cyclic configuration, which favours subsequent dehydrocyclization over linear, acyclic dehydrogenation. In contrast, microporous supports are less preferred as molecular diffusion rates and the accessibility to catalytically active sites might be limited for the rather bulky SAF-ranged hydrocarbons of the reaction feed. The porosity of the catalyst can be controlled by the choice of a suitable support as well as by post-synthesis support modifications, such as partial etching in acid or basic media.

[0029] According to an additional embodiment of the invention, the support is selected from SiO2, AI2O3, M(AIO2)(SiO2)x(H2O)y, CeO2, TiO2, SBA-15, MCM-41 or a zeolite. SiO2, AI2O3, M(AIO2)(SiO2)x(H2O)y, CeO2, TiO2, SBA-15 and MCM-41 are examples of supports that could be used according to the invention. Alternatively, microporous zeolites could be used. Preferably, the support is AI2O3. This support is suitable as a support for preparing catalysts that are active and selective in the dehydrocyclization and aromatization of hydrocarbons in the SAF range.

[0030] In a preferred embodiment of the invention, the support is neutralized with a neutralizing agent prior metal loading. As already discussed above, the support preferably is non-acidic when the final catalyst is used for dehydrocyclization and aromatization. However, it is possible to choose an acidic support for the synthesis of the catalyst and turn it into a non-acidic support by the addition of a neutralizing agent. Neutralizing agents can be, for example, counterions. In the case of an acidic support these counterions may be alkaline cations. Examples for alkaline cations include lithium, sodium, potassium, caesium, magnesium or calcium ions. Potassium ions (K+) are a cheap and easy source of neutralization agent, which is why they are preferably used, even more preferably in the form of KOH. The neutralization step may occur before loading the metal onto the support.

[0031] According to another embodiment of the invention, the metal is selected from Pt, Re, Pd, Ni, Ir, Cu, Cr, Te, V, Mo, or W. The named metals are able to catalyze the aromatization of hydrocarbons having a number of Cs to Cis, preferably Cg to C17, more preferably C10 to Ci6 carbon atoms. Particularly, noble metals like Pt, Pd and Ir are suitable for the dehydrocyclization of SAF-ranged hydrocarbons. Most preferred, Pt is used as it leads to an active catalyst forming aromatic compounds in the SAF range.

[0032] According to a further embodiment of the invention, the metal is loaded to the support via dry impregnation or co-precipitation. Different preparation methods lead to catalysts exhibiting diverse physicochemical properties, such as surface area, pore diameter and particle size of the metal, all of which influence the catalytic performances. While co-precipitation is more efficient in metal loading providing a controlled fine dispersion of metal particles on the support, dry impregnation is faster and simpler to conduct. Particularly when Pt is used as metal for the catalyst, co-precipitation is the preferred method of metal loading for the given reasons.

[0033] According to an additional embodiment of the invention, the metal loaded to the support has a particle size of 0.1 to 15.0 nm, preferably 0.5 to 5.0 nm. The particle size can be determined according to the BJH desorption model. The size of the metal particles loaded to the support affects the dehydrogenation / hydrogenolysis selectivity ratio of the resulting catalyst as well as the catalyst's activity. Hydrogenolysis in the context of this application refers to carbon-hydrogen or carbon-carbon decoupling reactions. According to the invention, however, a dehydrogenation, more exactly a dehydrocyclization, is desired. A smaller particle size favours the desired hydrogenation / dehydrogenation rates. However, small metal particles are prone to deactivation by sintering. It appears that the preferred particle sizes of the catalyst's metal give a sufficient dehydrogenation / hydrogenolysis selectivity ratio, catalyst activity and catalyst stability. In a preferred embodiment of the invention, the metal is, preferably strongly, anchored to the support. Thus, preferably there is a strong interaction between the metal and the support. The strong interaction promotes metal dispersion on the support and the anchorage can help to limit or even prevent leaching and sintering of the catalyst. A strong anchorage in the context of this application could, for example, be achieved by an association of the catalytic metal on the support with anchoring sites. The anchoring sites could be introduced to the support prior metal loading, for example by isomorphous substitution of the support's crystalline lattice. Furthermore, the anchoring sites could be provided by an anchorage metal, for example by tin (Sn). Experimental data show, for example, that the association of Pt as a catalytic metal with Sn as an anchorage metal on a zeolite support leads to a strong interaction between the catalytic Pt and the anchoring Sn, which results in a high Pt dispersion on the support and stabilizes the catalytic Pt against sintering due to stronger anchoring to the support. Alternatively, the strong anchorage could be achieved by other comparable binding forces.

[0034] According to another embodiment of the invention, the catalyst has a loading of metal per mass of catalyst which is 0.1 to 25 wt%, preferably 0.5 to 10 wt%, more preferably 0.5 to 5 wt%. This amount of metal loading led to a sufficient metal dispersion with the appropriate particle size and consequently to an enhanced yield of aromatic compounds in dehydrocyclization and aromatization.

[0035] According to a further embodiment of the invention, the catalyst is neutralized with a neutralizing agent after metal loading to the support and prior the use of the catalyst for dehydrocyclization and aromatization. As already discussed above, the final catalyst used for dehydrocyclization and aromatization preferably is non- acidic. Yet, an acidic support can be chosen for the synthesis of the catalyst, which is neutralized prior metal loading. According to another embodiment of the invention, an acidic support can be chosen for the synthesis of the catalyst, which is neutralized after metal loading (but before the catalyst is used for dehydrocyclization and aromatization). Initial acidity of the support can be beneficial or even required for the structure formation during catalyst synthesis. Additionally or alternatively, initial acidity of the support can help promote the initial dispersion of the metal on the support. Suitable neutralizing agents are the same as the ones mentioned above. One example according to the invention is acidic AI2O3, which can serve as a support. According to a preferred embodiment, the acidic AI2O3 can then be neutralized by, for example, KOH (with potassium ions being the neutralizing agent according to the preferred embodiment) after metal loading and before the use of the final catalyst for dehydrocyclization and aromatization.

[0036] According to an additional embodiment of the invention, the catalyst is reduced prior its use for dehydrocyclization and aromatization. During this step, the catalyst is reduced into its metallic form.

[0037] Preferably, the catalyst is reduced by molecular hydrogen at a temperature of 300°C or below. The reduction step can be conducted under H2 flow at various temperatures. Ideally, the temperature is 300 C or below as these relatively low temperatures are suitable for a sufficient reduction while, at the same time, they help to prevent sintering of the metal.

[0038] According to another embodiment of the invention, the catalyst is regenerated after its use for dehydrocyclization and aromatization by the following steps: (a) burning off coke, (b) oxidation, (c) removal of water and (d) reduction. Regeneration primarily consists of coke removal, which usually results in metal oxidation. Therefore, a reduction step is also required in order to restore the metallic state. Also, steps for preventing sintering can be introduced. The regeneration procedure allows to re-disperse the metal particles on the support so that the catalyst can be reactivated.

[0039] Brief description of the Figures

[0040] Further details, features, aims and advantages of the present invention are shown in the following, with reference to Figures 1 to 7, which show:

[0041] Figure 1 : Image of a product sample of a catalytical testing reaction during collection illuminated by UV light. Figure 2: (a) 1H NMR spectrum of a mixture of reaction products obtained from

[0042] 1-decene dehydrocyclization using 5 wt% Pt / AkCh or 5 wt% KPt / AkCh as catalyst, (b) Enlarged section of Fig. 2a. Ar. = aromatics.

[0043] Figure 3: (a) GC-FID signal of the reaction products obtained from 1-decene dehydrocyclization using 5 wt% Pt / AkCh or 5 wt% KPt / AkCh as catalyst (orange) and 1-decene feed (green), with mass spectrometry (MS) attribution of the signals, (b) Enlarged section of Fig. 3a in the Cio region with MS signal attribution.

[0044] Figure 4: GC-FID signal of the reaction products obtained from 1-decene dehydrocyclization using 5 wt% Pt / A Os (green) or 5 wt% KPt / AbC (black) as catalysts. Peaks highlighted in red correspond to aromatic compounds based on the MS analysis.

[0045] Figure 5: Conversion of n-decenes, selectivity towards Cio aromatic, and Cio aromatic production rate graphs as a function of time on stream (TOS).

[0046] Figure 6: 1H NMR. spectrum of the reaction products obtained from 1- tetradecene dehydrocyclization using 5 wt% Pt / AbC as catalyst.

[0047] Figure 7: GC-FID signal of the reaction products obtained from 1-tetradecene dehydrocyclization using 5 wt% Pt / AbC as catalyst (red) and 1- tetradecene feed (black) with MS signal attribution.

[0048] Experiments

[0049] The following examples are used to describe the invention. Based on the examples, the person skilled in the art can easily conclude that and how to vary certain parameters or structures as given in the above description.

[0050] Synthesis of dehydrocyclization and aromatization catalysts

[0051] Example 1 : 5 wt% Pt / AbC As a first example of a supported metal catalyst, commercial 5 wt% Pt / A Os (type 94 from Johnson Matthey) was used.

[0052] Example 2: 5 wt% KPt / AkCh

[0053] The commercially available catalyst of the first example was treated with KOH in order to affect its acidic properties, more exactly to neutralize it.

[0054] 300 mg of 5 wt% Pt / A Os was mixed with 9 mL of an aqueous solution of

[0055] 0.5 M KOH (252 mg of KOH dissolved in 9 mL water). After proper mixing, the resulting slurry was directly transferred in a centrifuge for separation. The retrieved powder was rinsed once with water and separated again using the centrifuge. The resulting catalyst was then dried at 120°C. No calcination step was performed.

[0056] Catalytic testing of the synthesized catalysts

[0057] Example 3: 1-decene dehydrocyclization over 5 wt% Pt / A Os

[0058] For the dehydrocyclization of 1-decene in a flow-reactor (phoenix reactor), 251 mg of 5 wt% Pt / A Os catalyst (meshed 0.25-0.5 mm, without any thermal pretreatment of the powdered catalyst) was placed within the down-flow tubular reactor (1 / 4" diameter), supported by a frit. The temperature was then raised under a constant flow of nitrogen to 450°C (reaction temperature). The flow of nitrogen was then interrupted, and the pure hydrocarbon feed was sent instead.

[0059] The reaction feed was pure 1-decene, fed at 0.01 mL / min. The reaction temperature was 450°C and the reaction pressure was 1 atm.

[0060] The reactor exhaust was cooled down with an acetone condenser (a towel saturated in acetone was wrapped along the 1 / 16" exhaust tubing to keep it cooled down). Liquid samples were collected at different times on stream (the gas was allowed to escape).

[0061] Example 4: 1-decene dehydrocyclization over 5 wt% KPt / AkCh

[0062] In this example reaction, the same reaction conditions as for the previous example reaction (example 3) were applied, the only difference being the use of 5 wt% KPt / AkCh as a catalyst instead of 5 wt% Pt / AkCh.

[0063] Example 5: 1-tetradecene dehydrocyclization over 5 wt% Pt / AkCh

[0064] In this example reaction, again the same reaction conditions as for example reaction 3 were applied, but with the following differences:

[0065] The reaction feed was pure 1-tetradecene, and 354.7 mg of the meshed catalyst was introduced within the 1 / 4" diameter reactor (reactor is completely filled). The feed flow rate was set at 0.01-0.05 mL / min.

[0066] No nitrogen pre-treatment was performed, and the catalyst was heated-up already under a feed flow rate of 0.05 mb / min.

[0067] Characterization

[0068] During all catalytic testing reactions, gas release was observed. This is indicative for H2 generation and, thus, for the successful dehydrocyclization of the olefins used as reaction educts into aromatics.

[0069] Moreover, as exemplarily shown in Figure 1, the reaction products of all catalytic testing reactions were UV-responsive. This further indicates the presence of conjugated unsaturated hydrocarbons (double-bonds).

[0070] The reaction products from 1-decene dehydrocyclization with 5 wt% Pt / AkCh as catalyst (example 3) and 1-decene dehydrocyclization with 5 wt% KPt / AkCh as catalyst (example 4) were then analyzed by 1H NMR. Figure 2 shows the resulting 1 H NMR spectrum, which proves the presence of aromatics compounds. The ratio between aromatic and olefinic protons is of around 0.8 %.

[0071] Next, the mixed reaction products of catalytic testing reactions example 3 and 4 were analyzed by gas chromatography with flame ionization detector (GC-FID) and gas chromatography-mass spectrometry (GC-MS). The results of this analysis are shown in Figures 3 and 4. Figures 3 and 4 prove that the aromatics formed in the catalytic testing reactions example 3 and 4 are all within a range of CP = Cio. According to the results of GC-FID and GC-MS measurements, no lighter BTX aromatics (having a carbon count of Ce-Cs) have been formed. Furthermore, according to GC-FID and GC-MS analysis, the yield of aromatic compounds is 0.9%, which is in the same order of magnitude as the ratio between aromatic and olefinic protons observed in this sample by 1H NMR. spectroscopy.

[0072] Figure 5 illustrates the conversion of n-decenes, selectivity towards Cio aromatic, and Cio aromatic production rate graphs as a function of time on stream (TOS). The data show that Cio conversions are low to moderate (below 20%) and selectivity remains rather poor. The reason for this may be that the catalytic testing reactions example 3 and 4 were measured at a relatively low temperature and a high space velocity (which means low contact time) in comparison to literature data because of technical limitations. Higher temperature and lower space velocity are indeed expected to promote conversion and aromatic formation.

[0073] By-products are mostly linear alkene compounds, most likely coming from the hydrogenolysis of the Cio educt, i.e. 1-decene.

[0074] Figure 5 shows that the KOH treatment affected the catalyst performances significantly. Nevertheless, it must be acknowledged that straight comparison between 5 wt% Pt / A Os (example 3) and 5 wt% KPt / AbOs (example 4) is not possible since the corresponding conversion levels of the two catalysts differ. The KOH treatment seems to have resulted in a higher production of aromatic compounds and overall conversion level of the catalyst. Up to this point, however, it remains unclear how KOH treatment affects Cio conversion. KOH treatment of the 5 wt% Pt / AbOs catalyst might, for example, affect acidity, perturb the Pt sites through sintering or leaching, or change textural properties of the catalyst. Figure 6 shows a 1H NMR spectrum of the reaction products from 1-tetradecene dehydrocyclization using 5 wt% Pt / A Os as catalyst (example 5). Again, the presence of aromatics and conjugated olefins can be seen.

[0075] Figure 7 illustrates the GC-FID and GC-MS results of example 5. According to the data of 1-tetradecene dehydrocyclization, some shorter BTX aromatics seem to have formed (Ce-Cs aromatics), but the vast majority of aromatic products are Ci4 species. Some polyaromatics were also highlighted (bi- and tricyclic aromatics) as evidenced by the presence of some naphthalene and anthracene m / z contribution in MS data. The Ci4 fraction of the reaction products is approximately composed of 13% aromatic products (with only about 1% being bi- or tricyclic aromatics, with the contribution of anthracene being below 0.01%).

[0076] Due to the unstable space velocity of this measurement (due to experimental issues with the used HPLC pump), the actual residence time (1 / WHSV) and time on stream for this experiment could not be determined.

[0077] In summary, the data show that contacting Cio or Ci4 linear olefins (1-decene or 1-tetradecene) with 5 wt% Pt supported on alumina (AI2O3) at room pressure and at a temperature of 450°C resulted in dehydrogenation, while converting the linear olefins into polyolefins, cyclic olefins and aromatics (as well as polyaromatics).

[0078] Moreover, the modification of the Pt catalyst with KOH significantly affected the conversion level and selectivity, which might be due to the absence of acidic moieties.

Claims

Claims1. A method for selective dehydrocyclization and aromatization of linear or branched hydrocarbons in the SAF range into aromatics in the SAF range,- wherein the hydrocarbons comprise alkanes, olefins or mixtures thereof,- wherein the hydrocarbons have a number CE of carbon atoms, wherein E = 8 - 18, preferably E = 9 - 17, more preferably E = 10 - 16,- wherein the aromatics have a number CP of carbon atoms, wherein P = 8 - 18, preferably P = 9 - 17, more preferably P = 10 - 16,- and wherein the dehydrocyclization and aromatization is catalyzed by use of a supported metal catalyst comprising o a support and o a metal active for hydrogenation or dehydrogenation of hydrocarbons which is loaded to the support.

2. Method according to claim 1, wherein the dehydrocyclization and aromatization is performed at a reaction temperature of 400°C to 600°C, preferably 450°C to 550°C, and at a pressure of 0.1-10 bara, preferably between 1-3 bara, more preferably at atmospheric pressure.

3. Method according to claim 1 or 2, wherein the support is non-acidic.

4. Method according to one of claims 1 to 3, wherein the support is mesoporous, microporous or nonporous, preferably mesoporous.

5. Method according to one of claims 1 to 4, wherein the support is selected from SiO2, AI2O3, M(AIO2)(SiO2)x(H2O)y, CeO2, TiO2, SBA-15, MCM-42 or ZSM- 5, preferably the support is AI2O3.

6. Method according to one of claims 1 to 5, wherein the support is neutralized with a neutralizing agent prior metal loading.

7. Method according to one of claims 1 to 6, wherein the metal is selected from Pt, Re, Pd, Ni, Ir, Cu, Cr, Te, V, Mo, or W, preferably it is Pt.

8. Method according to one of claims 1 to 7, wherein the metal is loaded to the support via dry impregnation or co-precipitation, preferably via coprecipitation.

9. Method according to one of claims 1 to 8, wherein the metal loaded to the support has a particle size of 0.5 to 15.0 nm, preferably 0.5 to 5.0 nm.

10. Method according to one of claims 1 to 9, wherein the metal is, preferably strongly, anchored to the support.

11. Method according to one of claims 1 to 10, wherein the catalyst has a loading of metal per mass of catalyst which is 0.1 to 25 wt%, preferably 0.5 to 10 wt%, more preferably 0.5 to 5 wt%.

12. Method according to one of claims 1 to 5 or 7 to 11, wherein the catalyst is neutralized with a neutralizing agent after metal loading to the support and prior the use of the catalyst for dehydrocyclization and aromatization.

13. Method according to one of claims 1 to 12, wherein the catalyst is reduced prior its use for dehydrocyclization and aromatization.

14. Method according to claim 13, wherein the catalyst is reduced by molecular hydrogen at a temperature of 300°C or below.

15. Method according to one of claims 1 to 14, wherein the catalyst is regenerated after its use for dehydrocyclization and aromatization by the following steps:(a) burning off coke,(b) oxidation,(c) removal of water and(d) reduction.

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