Catalyst and method for removing mercaptans from hydrocarbon streams

Abstract

The present invention relates to a catalyst for use in a process for removing mercaptans and optionally disulfides (if present) from hydrocarbon streams (especially C4 streams) in the presence of higher diolefins (especially C5 dienes). At the same time, the present invention also relates to a process for removing mercaptans and disulfides (if present) from hydrocarbon streams (especially C4 streams) by thioetherification of mercaptans with polyunsaturated hydrocarbons, in one embodiment, in the presence of 1-butene, wherein the process is carried out in a reactor fed with hydrogen in the presence of higher diolefins (especially C5 dienes).

Description

[0001] The present invention relates to a catalyst for use in a process for removing mercaptans and optionally disulfides from hydrocarbon streams, especially C4 streams, in the presence of higher diolefins, especially C5 dienes. The present invention also relates to a process for removing mercaptans from hydrocarbon streams, especially C4 streams, by thioetherifying mercaptans with polyunsaturated hydrocarbons, in one embodiment in the presence of 1-butene, wherein the process is carried out in the presence of higher diolefins, especially C5 dienes, in a reactor fed with hydrogen.

[0002] Mixtures of C4 hydrocarbons are raw materials for the downstream petrochemical industry. They come from steam crackers (so-called "cracked C4") or from fluid catalytic crackers (so-called "FCC C4"). Mixtures of C4 hydrocarbons from different sources are also available, so-called "C4 cuts". In order to utilize the individual components, C4 mixtures need to be separated into their components with the highest possible purity.

[0003] Mercaptans are R-SH compounds, wherein R is a hydrocarbon group, S is sulfur and H is hydrogen. Mercaptans are also referred to as thiols. Important representatives of mercaptans are methyl mercaptan and ethyl mercaptan, also referred to as methyl mercaptan and ethyl mercaptan, respectively. In the context of the present invention, disulfides are organic compounds with SS bonds. An important representative is dimethyl disulfide. Mercaptans occur in C4 hydrocarbon mixtures at most 200 ppm as undesirable accompanying substances.

[0004] Industrial C4 hydrocarbon mixtures from catalytic crackers (FCC C4) or steam crackers (cracked C4) generally contain not only saturated and monounsaturated compounds, but also polyunsaturated compounds. Before the individual compounds can be separated from these mixtures, it is generally necessary to remove the other compounds as completely as possible. This can be done by physical methods, such as distillation, extractive distillation or extraction, but can also be done by selective chemical conversion of the components to be removed. Special attention must be paid here to the fullest possible removal of pollutants present in the C4 hydrocarbon mixture, such as oxygen-containing components, nitrogen-containing components and sulfur-containing components, because these pollutants can have an adverse effect on individual process steps as catalyst poisons. Although these pollutants are usually present only in trace amounts in cracked C4, they may also be present in higher concentrations in FCC C4 streams.

[0005] The composition of the raw materials may vary significantly depending on the source of the material.The C4 components listed are additionally accompanied by hydrocarbons having fewer or more carbon atoms and small amounts of contaminants such as mercaptans, sulfides, disulfides and nitrogen- and oxygen-containing compounds.

[0006] In a variant, FCC C4 can be post-treated so that the concentration of isobutane is first reduced by a distillation step. At the same time, the low boilers present in the mixture (e.g., C3 hydrocarbons, light oxygen-containing, nitrogen-containing and sulfur-containing compounds) are removed or minimized. In the following steps that take place in the tower, all high boilers (e.g., C5 hydrocarbons, heavy oxygen-containing, nitrogen-containing and sulfur-containing compounds) are removed via the bottom. In the next step, isobutene is removed, for example by reacting it with methanol to obtain methyl tert-butyl ether (MTBE), which is removed by distillation. If pure isobutene is to be obtained, the methyl tert-butyl ether can then be cleaved to obtain isobutene and methanol.

[0007] In order to further post-process the C4 mixture, the still remaining polyunsaturated compounds must be converted into the corresponding monounsaturated compounds by a selective hydrogenation process. Then 1-butene and the remaining isobutane can be removed with sufficient purity by distillation, and the remaining 2-butene and normal butane are further post-processed. Usually, 2-butene is converted into octenes by dimerization, which are then converted into plasticizer alcohols by hydroformylation and hydrogenation. Saturated C4 hydrocarbons can be used as propellants, for example, for aerosols.

[0008] If the selective hydrogenation process before the removal of 1-butene does not reduce the concentration of polyunsaturated compounds to values ​​less than 10 ppm, the purity requirements for 1-butene used in the polymerization are not met. Polyunsaturated compounds also inhibit the catalytic activity of catalysts used for the dimerization of 2-butene.

[0009] The requirements on selectivity in processes for the selective hydrogenation of polyunsaturated hydrocarbons are particularly high, since overhydrogenation, i.e. hydrogenation of monounsaturated compounds, or isomerization of terminal double bonds to internal double bonds, leads to the destruction of valuable products. In the fine purification of streams which already have a low content of polyunsaturated compounds, the concentration of polyunsaturated compounds must simultaneously be further reduced to values ​​below 10 ppm by weight.

[0010] In the case of catalytic C4 streams, it can now happen that, in addition to light sulfur-containing components (e.g. H2S, COS or MeSH) which have been removed by distillation during the removal of low boilers and higher-boiling sulfur compounds (such as dimethyl disulfide which is removed later in the C5 column), there are also intermediate boilers of the mercaptan type (e.g. ethyl mercaptan). These cannot be easily removed from the C4 stream by distillation. The presence of mercaptans during the work-up of the C4 stream is undesirable or interferes with the work-up.

[0011] If mercaptans (e.g. ethyl mercaptan) and optionally disulfides are present in the feed for the selective hydrogenation, they inhibit the catalytic conversion of 1,3-butadiene. This means that branched polyunsaturated compounds can be present in the subsequent products (e.g. 1-butene) and impair their purity. If polyunsaturated compounds enter the feed for the oligomerization of n-butenes due to insufficient conversion in the selective hydrogenation caused by the mercaptan content, they deactivate the oligomerization catalyst.

[0012] It is known that feeding a selective hydrogenation catalyst together with a sulfur-containing component can lead to the formation of a hydroisomerization active catalyst. The presence of mercaptans in the feed for the selective hydrogenation can lead to the formation of such a hydroisomerization catalyst, resulting in the undesired isomerization of 1-butene to 2-butene.

[0013] DE 10 2012 212 317 A1 accordingly proposes a process for the thioetherification of mercaptans using polyunsaturated hydrocarbons, using a heterogeneous catalyst containing palladium as the catalytically active metal and adding hydrogen, the hydrogen being used in a defined ratio to the polyunsaturated hydrocarbon. DE 10 2012 212 317 A1 also provides a detailed description of the further prior art for removing mercaptans from hydrocarbon streams.

[0014] However, a disadvantage of the catalysts used therein is that the thioetherification of mercaptans is inhibited by the presence of higher diolefins (such as C5 dienes, in particular isoprene) and does not proceed to completion. This means that mercaptans (such as ethyl mercaptan and / or methyl mercaptan) remain in the hydrocarbon stream and can lead to the problems already described.

[0015] Furthermore, if isoprene and / or other long-chain polyunsaturated hydrocarbons are also present, disulfides such as dimethyl disulfide that may be present in the C4 stream are cleaved into two equivalents of methyl mercaptan. This results in the mercaptan content actually increasing, rather than being reduced by thioetherification.

[0016] It was therefore an object of the present invention to provide a catalyst which, even in the presence of higher diolefins, leads to an (almost) complete conversion of the mercaptans and optionally disulfides (if present) present in hydrocarbon streams, i.e. including mercaptans which may otherwise be formed in situ by disulfide cleavage. A further object was to provide a process which does not suffer from the abovementioned problems and which makes it possible to carry out the thioetherification of mercaptans, in particular to completion.

[0017] This object is achieved by the catalyst according to the invention and the process according to the invention.

[0018] The present invention provides a heterogeneous catalyst for removing mercaptans and, if present, disulfides from hydrocarbon streams in the presence of higher diolefins, wherein the catalyst is a shell catalyst, wherein the catalyst comprises aluminum oxide, silica gel or activated carbon as support material and palladium and platinum as catalytically active metals, and wherein the catalyst has a palladium concentration of at most 2.0% by weight, preferably at most 1.0% by weight, more preferably at most 0.5% by weight, a platinum concentration of at most 1.0% by weight, preferably at most 0.5% by weight, more preferably at most 0.2% by weight, and a total metal dispersion of at least 70%. The stated values ​​for the palladium and platinum concentrations refer in each case to the total catalyst. The term "shell catalyst" refers to a form of catalyst in which the core consists of a support material to which a shell of Pd / PdO and Pt / PtO is applied by a spraying process and subsequent calcination, the layer thickness of the shell and the depth of penetration into the support being in each case only a few μm.

[0019] The hydrocarbon stream preferably comprises C2-C8 olefins, more preferably C3-C6 olefins, and most preferably C4 olefins. The hydrocarbon stream to be purified of mercaptans and disulfides (if present) is particularly a C4 hydrocarbon stream (C4 stream). Suitable olefins include alpha-olefins, normal olefins and cycloolefins, preferably normal olefins. In a preferred embodiment, olefins are n-butenes. The olefins are not usually used in pure form, but as industrially available mixtures, such as the cracked C4 or FCC C4 mentioned. Therefore, the term hydrocarbon stream used in addition in the present invention is understood to mean any type of mixture containing the relevant olefins, and the amount of the olefins enables the possible process steps of the downstream to be economically purified.

[0020] In the context of the present invention, the term "higher diene" refers to at least C5 diene or a diene with more than 5 carbon atoms. Higher diene is preferably C5 diene, in particular isoprene. Diolefins are usually present in low concentrations in industrial hydrocarbon streams of mercaptans to be purified according to the present invention. Compared with, for example, butadiene, higher dienes are more difficult to react in selective hydrogenation (see also WO 2012 / 004081 A1), which means that the inhibition of the reaction by C5 diene in thioetherification is also plausible.

[0021] The catalyst used in the process of the invention is a shell catalyst consisting of a support material and palladium and platinum as catalytically active metals, by means of which the mercaptans in the hydrocarbon stream can be completely converted into thioethers. The support material is, for example, aluminum oxide, silica gel or activated carbon. The support material used is preferably aluminum oxide.

[0022] The catalyst has a palladium concentration of at most 2.0 wt%, preferably at most 1.0 wt%, more preferably at most 0.5 wt%. The catalyst also has a platinum concentration of at most 1.0 wt%, preferably at most 0.5 wt%, more preferably at most 0.2 wt%.

[0023] The internal surface area of ​​the catalyst (determined by gas adsorption according to DIN ISO 9277) is preferably 50 m 2 / g to 400m 2 / g, more preferably 100m 2 / g and 300m 2 / g, particularly preferably between 200m 2 / g and 300m 2 / g.

[0024] In a preferred embodiment, the catalyst additionally has at least 0.5 m 2 / g, preferably at least 1.0m 2 / g, more preferably at least 1.5m 2 =Total metal surface area of ​​100 Å / g (determined by CO pulse chemisorption according to AN-SOP 1954, 1st edition). Total metal surface areas smaller than the values ​​shown result in reduced catalyst activity.

[0025] The catalyst according to the invention has a total metal dispersion of at least 70%, preferably at least 80%. The total metal dispersion indicates how well the metal / metal oxide is dispersed on the surface. The dispersion on the surface can be controlled by the duration and intensity of spraying the support material with a Pd / Pt salt solution during catalyst preparation. "Dispersion" here refers to a heterogeneous mixture of dispersed phase (Pd / Pt) and dispersion medium (support). The higher the dispersion on the surface, the higher the activity of the catalyst. Surprisingly, it was found that if the total metal dispersion is below 70%, complete conversion of mercaptans cannot be achieved.

[0026] The present invention further provides a process for removing mercaptans and disulfides, if present, from hydrocarbon streams by thioetherification of the mercaptans with polyunsaturated hydrocarbons in the presence of at least one higher diolefin, wherein the process is carried out in a reactor fed with hydrogen, wherein the molar ratio of hydrogen to polyunsaturated hydrocarbon is not greater than 1. The process uses a heterogeneous catalyst as described above which comprises palladium and platinum as catalytically active metals, wherein the catalyst has a palladium concentration of at most 2.0% by weight, preferably at most 1.0% by weight, more preferably at most 0.5% by weight, a platinum concentration of at most 1.0% by weight, preferably at most 0.5% by weight, more preferably at most 0.2% by weight, and a total metal dispersion of at least 70%, preferably at least 80%. The values ​​stated for the palladium and platinum concentrations are in each case referenced to the total catalyst.

[0027] The hydrocarbon stream preferably comprises C2-C8 olefins, more preferably C3-C5 olefins, and most preferably C4 olefins. The hydrocarbon stream to be purified of mercaptans and disulfides is particularly a C4 hydrocarbon stream (C4 stream). Suitable olefins include alpha-olefins, normal olefins and cycloolefins, preferably normal olefins. In a preferred embodiment, the olefin is n-butene. Olefins are not usually used in pure form, but as industrially available mixtures, such as the cracked C4 or FCC C4 mentioned. Therefore, the term hydrocarbon stream used in addition in the present invention is understood to mean any type of mixture containing the relevant olefins, the amount of which enables the possible process steps of the downstream of the purification to be economically carried out.

[0028] In the context of the present invention, the term "higher diene" refers to at least C5 diene or a diene with more than 5 carbon atoms. Higher diene is preferably C5 diene, in particular isoprene. Diolefins are usually present in low concentrations in industrial hydrocarbon streams from which mercaptans are to be purified according to the present invention. Compared with butadiene (see also WO 2012 / 004081 A1), higher dienes react more difficultly in selective hydrogenation, which means that the inhibition of the reaction by C5 diene in thioetherification is also reasonable.

[0029] By using a heterogeneous catalyst comprising palladium and platinum as catalytically active metals, the process according to the invention makes it possible to completely convert mercaptans into high-boiling thioethers while almost completely suppressing a significant isomerization of 1-butene to internal butenes and completely preventing hydrogenation of butenes. If the concentration of 1-butene in the hydrocarbon stream is above the concentration at which the double bond of 1-butene is isomerized to 2-butene at thermodynamic equilibrium and / or hydrogenated to n-butane, the conversion of 1-butene to 2-butene by isomerization and / or hydrogenation to n-butane is less than 5%, preferably less than 3%, most preferably less than 2%.

[0030] It has been found that in the presence of polyunsaturated hydrocarbons and hydrogen, mercaptans can be converted to higher boiling sulfides below the detection limit, while the isomerization of 1-butene is greatly suppressed and the hydrogenation of butene is completely avoided. The detection limit for mercaptans is currently about 50 ppbw, i.e. 50×10 by weight. -9 proportion.

[0031] In the context of the present invention, it must be noted that the amount of hydrogen used in the process is at most 1 (equimolar) relative to the polyunsaturated hydrocarbons present in the hydrocarbon mixture. The molar ratio of hydrogen to polyunsaturated hydrocarbons is preferably between 0.01 and 0.8. It is more preferably between 0.1 and 0.5.

[0032] The main advantage of this process is that the low hydrogen content means that the 1-butene present in the C4 stream undergoes very little isomerization and remains available as a valuable product. Only by the restrictions that must be strictly met on the amount of hydrogen present in the feed, a process is obtained in which the mercaptans are etherified with polyunsaturated C4 hydrocarbons to high-boiling sulfides to a concentration below 50 ppbw, which does not require the concomitant hydrogenation of the monounsaturated butenes also present in the feed and a significant isomerization of the 1-butene. However, it is not possible to completely omit hydrogen, since without hydrogen there is no conversion of the mercaptans.

[0033] A further advantage of the process according to the invention is that it leads to a complete conversion of mercaptans even in the presence of higher dienes.

[0034] The polyunsaturated hydrocarbons thioetherified with mercaptans are preferably 1,3-butadiene and / or but-3-ene-1-yne and / or 1,2-butadiene. These dienes and acetylene are present only in small amounts in FCC C4 in particular and must be fully hydrogenated downstream in any case and are therefore no longer usable as valuable products. In cracked C4 streams with a high 1,3-butadiene content, 1,3-butadiene is first removed in a separate process and used. The residual butadiene remaining in the C4 stream can then be used for thioetherification.

[0035] Another particular advantage of this process is that, in addition to the highly reactive mercaptan methyl mercaptan, higher mercaptans (eg ethyl mercaptan) can also react and thus be removed.

[0036] In this method, carbon monoxide can be optionally added to the hydrocarbon mixture in addition. Based on the mass of the hydrocarbon mixture, the content of carbon monoxide in the feed is between 0.05 and 20ppm carbon monoxide in this case. The amount of carbon monoxide added is preferably between 0.5 and 5ppm. The amount measured higher than 20ppm does not further improve the result. Carbon monoxide is metered into the reactor alone or mixed with the C4 stream of the feed. Carbon monoxide can be used as an additional moderator to reduce the isomerization of 1-butene to 2-butene.

[0037] The inlet temperature of the reactor feed is preferably in the range of 0 to 180° C., more preferably in the range of 60° C. to 150° C., particularly preferably in the range of 80° C. to 130° C. The pressure is preferably in the range of 2 bar to 50 bar, more preferably in the range of 6 bar to 40 bar, particularly preferably in the range of 10 bar to 30 bar. In a preferred embodiment, the hydrogen is already completely dissolved in the hydrocarbon stream. In this case, the pressure must be selected so that the hydrogen remains completely dissolved and no gas phase is generated in the reactor.

[0038] The thioetherification is preferably operated as a liquid phase process. This means that all components are present in the liquid phase at the catalyst or introduced into the reactor in liquid form. In particular, this means that the hydrogen and the carbon monoxide which is optionally present are completely dissolved in the liquid phase. The hydrogen is therefore added to the hydrocarbon mixture in finely dispersed form and in such an amount that the liquid phase is always homogeneous before being fed into the reactor.

[0039] The hydrocarbon mixture to be etherified may contain mercaptans and disulfides (if present) in the range of 0.01 to 200 ppm by weight. The thioetherification may be carried out in one or more reaction stages. If the content of mercaptans and disulfides (if present) in the feed is so high that the required amount of hydrogen is no longer soluble in the feed, the feed may be diluted by circulation. Alternatively, the hydrogen may be added in several portions distributed over the length of the reactor or over the individual reaction stages.

[0040] After the mercaptans, including those formed from the optionally present disulfides, have been converted into high-boiling sulfides, it is possible to remove these sulfides by distillation. As a result, the sulfide content of the remaining C4 hydrocarbon mixture can be reduced to less than 50 ppb by weight. Together with the possible removal of low boilers upstream of the thioetherification reactor and the distillation of high boilers downstream of the thioetherification reactor, this means that it is possible to completely remove all sulfur-containing components from the C4 hydrocarbon mixture.

[0041] The concentration of polyunsaturated olefins can be measured online by gas chromatography, allowing the amount of hydrogen to be set precisely therefrom. The same applies to the sulfur compounds.

[0042] The process is preferably used for mercaptan-containing C4 hydrocarbon mixtures originating from a catalytic cracker (FCC C4) or a steam cracker (Cracked C4). Of course, C4 fractions can also be processed.

[0043] The C4 hydrocarbon mixture used as feed is preferably initially subjected to the removal of low boilers, in particular isobutane, by distillation. Optionally, this process is employed before the removal of isobutane.

[0044] The present invention is illustrated below by way of examples. However, these examples are merely illustrative and should not be considered as limiting.

[0045] Embodiment 1 (not the present invention):

[0046] The tubular reactor was filled with 540 mL of catalyst containing 0.5 wt% Pd on Al2O3. A C4 mixture was passed through the reactor at 4 kg / h at 90°C and 20 bar pressure. The C4 mixture had the following composition:

[0047] 0.5 wt.-% 1,3-butadiene, 13.8 wt.-% butane, 40.3 wt.-% 2-butene, 20.3 wt.-% 1-butene, 22.0 wt.-% isobutene and 3.1 wt.-% C5 hydrocarbons, as well as 120 wt.-ppm isoprene, 2.8 wt.-ppm sulfur from ethanethiol and 6.0 wt.-ppm sulfur from dimethyl disulfide.

[0048] 4.4 Nl / h of hydrogen were metered into this mixture upstream of the reactor. The composition of the effluent from the reactor was as follows:

[0049] 0.4 wt% of 1,3-butadiene, 14.1 wt% of butane, 40.3 wt% of 2-butene, 20.3 wt% of 1-butene, 21.8 wt% of isobutylene and 3.1 wt% of C5 hydrocarbons, as well as 100 wtppm of isoprene, 0.7 wtppm of sulfur from ethanethiol and 2.2 wtppm of sulfur from dimethyl disulfide. 1.5 wtppm of sulfur from methyl mercaptan and 4.4 wtppm of sulfur from high boiling point compounds were also detected.

[0050] This corresponds to a conversion of 75% of ethanethiol, as well as 38.3% of dimethyl disulfide into high-boiling sulfur compounds and 25% of dimethyl disulfide into methyl mercaptan.

[0051] Complete conversion of ethanethiol was not achieved and, in addition, for methyl mercaptan, additional mercaptans were formed from dimethyl disulfide.

[0052] Embodiment 2 (the present invention):

[0053] The tubular reactor was filled with 540 mL of a catalyst containing 0.5 wt% Pd and 0.2 wt% Pt on Al2O3. A C4 mixture was passed through the reactor at a continuous rate of 4 kg / h at 90°C and 20 bar pressure. The C4 mixture had the following composition:

[0054] 0.6% by weight of 1,3-butadiene, 12.3% by weight of butane, 40.5% by weight of 2-butene, 19.5% by weight of 1-butene, 23.8% by weight of isobutene and 3.3% by weight of C5 hydrocarbons, as well as 95 ppm by weight of isoprene, 3.4 ppm by weight of sulfur from ethanethiol and 3.2 ppm by weight of sulfur from dimethyl disulfide.

[0055] 4.4 Nl / h of hydrogen were metered into this mixture upstream of the reactor. The composition of the effluent from the reactor was as follows:

[0056] 0.5 wt.% of 1,3-butadiene, 12.6 wt.% of butane, 39.5 wt.% of 2-butene, 19.5 wt.% of 1-butene, 24.6 wt.% of isobutene and 3.3 wt.% of C5 hydrocarbons, as well as 80 wt.ppm of isoprene, 0.0 wt.ppm of sulfur from ethanethiol and 1.2 wt.ppm of sulfur from dimethyl disulfide, and 5.4 wt.ppm of sulfur from high boiling point compounds.

[0057] No methyl mercaptan was detected. This corresponds to 100% of ethyl mercaptan and 62.5% of dimethyl disulfide converted to high-boiling sulfur compounds.

[0058] By using the catalyst according to the invention, the conversion of mercaptans is significantly increased compared to catalysts not according to the invention.

[0059] Embodiment 3 (not the present invention):

[0060] The tubular reactor was filled with 540 mL of a catalyst containing 0.5 wt% Pd and 0.2 wt% Pt on Al2O3. The catalyst had the following characteristics determined by CO pulse chemisorption according to ANSOP 1954 1st edition.

[0061]

[0062] The C4 mixture was passed through the reactor at a continuous rate of 4 kg / h at 90°C and 20 bar pressure. The C4 mixture had the following composition:

[0063] 0.7% by weight of 1,3-butadiene, 13.6% by weight of butane, 40.4% by weight of 2-butene, 20.3% by weight of 1-butene, 22.2% by weight of isobutene and 2.9% by weight of C5 hydrocarbons, as well as 87 ppm by weight of isoprene, 5.1 ppm by weight of sulfur from ethanethiol and 5.1 ppm by weight of sulfur from dimethyl disulfide.

[0064] 5.3 Nl / h of hydrogen were metered into the mixture upstream of the reactor. The composition of the effluent from the reactor was as follows:

[0065] 0.4 wt% of 1,3-butadiene, 13.7 wt% of butane, 39.1 wt% of 2-butene, 20.8 wt% of 1-butene, 23.2 wt% of isobutylene and 2.9 wt% of C5 hydrocarbons, as well as 72 wtppm of isoprene, 1.4 wtppm of sulfur from ethanethiol and 1.7 wtppm of sulfur from dimethyl disulfide. In addition, 0.9 wtppm of sulfur from methyl mercaptan and 6.2 wtppm of sulfur from high boiling point compounds were detected.

[0066] This corresponds to 72.5% of ethanethiol, and 35.3% of dimethyl disulfide converted to high-boiling sulfur compounds and 17.6% of dimethyl disulfide converted to methyl mercaptan. Complete conversion of ethanethiol was not achieved, and methyl mercaptan also meant that additional mercaptans were formed from dimethyl disulfide.

[0067] Embodiment 4 (the present invention):

[0068] The tubular reactor was filled with 540 mL of a catalyst containing 0.5 wt% Pd and 0.2 wt% Pt on Al2O3. The catalyst had the following characteristics determined by CO pulse chemisorption according to ANSOP 1954 1st edition.

[0069]

[0070] The C4 mixture was passed through the reactor at a continuous rate of 4 kg / h at 90°C and 20 bar pressure. The C4 mixture had the following composition:

[0071] 0.7% by weight of 1,3-butadiene, 13.0% by weight of butane, 39.8% by weight of 2-butene, 19.2% by weight of 1-butene, 23.9% by weight of isobutene and 3.4% by weight of C5 hydrocarbons, as well as 112 ppm by weight of isoprene, 5.7 ppm by weight of sulfur from ethanethiol and 5.4 ppm by weight of sulfur from dimethyl disulfide.

[0072] 5.6 Nl / h of hydrogen were metered into the mixture upstream of the reactor. The composition of the effluent from the reactor was as follows:

[0073] 0.4 wt% of 1,3-butadiene, 13.0 wt% of butane, 40.4 wt% of 2-butene, 18.9 wt% of 1-butene, 23.8 wt% of isobutene and 3.4 wt% of C5 hydrocarbons, as well as 96 wtppm of isoprene, 0.0 wtppm of sulfur from ethanethiol and 0.7 wtppm of sulfur from dimethyl disulfide.

[0074] No methyl mercaptan was detected. This corresponds to 100% of ethyl mercaptan and 87% of dimethyl disulfide converted to high-boiling sulfur compounds.

[0075] Embodiment 5 (the present invention):

[0076] The tubular reactor was filled with 540 mL of a catalyst containing 0.5 wt% Pd and 0.2 wt% Pt on Al2O3. The catalyst had the following characteristics determined by CO pulse chemisorption according to ANSOP 1954 1st edition.

[0077]

[0078] The C4 mixture was passed through the reactor at a continuous rate of 4 kg / h at 90°C and 20 bar pressure. The C4 mixture had the following composition:

[0079] 0.6% by weight of 1,3-butadiene, 12.4% by weight of butane, 39.8% by weight of 2-butene, 19.9% ​​by weight of 1-butene, 23.9% by weight of isobutene and 3.8% by weight of C5 hydrocarbons, as well as 124 ppm by weight of isoprene, 3.3 ppm by weight of sulfur from ethanethiol and 2.2 ppm by weight of sulfur from dimethyl disulfide.

[0080] 4.4 Nl / h of hydrogen were metered into this mixture upstream of the reactor. The composition of the effluent from the reactor was as follows:

[0081] 0.4 wt% of 1,3-butadiene, 12.6 wt% of butane, 39.8 wt% of 2-butene, 19.7 wt% of 1-butene, 23.4 wt% of isobutene and 3.8 wt% of C5 hydrocarbons, as well as 104 wtppm of isoprene, 0.0 wtppm of sulfur from ethanethiol and 0.6 wtppm of sulfur from dimethyl disulfide.

[0082] No methyl mercaptan was detected. This corresponds to 100% of ethyl mercaptan and 72.7% of dimethyl disulfide converted to high-boiling sulfur compounds.

[0083] In a comparison of Examples 3 to 5, it is shown that when a catalyst with a total metal dispersion of less than 70% is used, full conversion of mercaptans cannot be achieved. Full conversion is only achieved in Examples 4 and 5 when the total metal dispersion on the catalyst is above 70%.

Claims

1. Use of a heterogeneous catalyst for removing mercaptans and optionally disulfides from hydrocarbon streams in the presence of higher diolefins, wherein the catalyst is a shell catalyst, characterized in that The catalyst comprises alumina, silica gel or activated carbon as support material and palladium and platinum as catalytically active metals, wherein the catalyst has a palladium concentration of at most 2.0 wt. %, a platinum concentration of at most 1.0 wt. %, and a total metal dispersion of at least 70%.

2. The use according to claim 1, characterized in that The catalyst has at least 0.5 m 2 / g total metal surface area.

3. The use according to claim 2, characterized in that: The catalyst has at least 1.0 m 2 / g total metal surface area.

4. The use according to claim 2, characterized in that: The catalyst has at least 1.5 m 2 / g total metal surface area.

5. The use according to any one of claims 1 to 4, characterized in that The catalyst has a total metal dispersion of at least 80%.

6. A process for removing mercaptans and optionally disulfides from hydrocarbon streams by thioetherification of mercaptans with polyunsaturated hydrocarbons in the presence of at least one higher diolefin, wherein the process is carried out in a reactor to which hydrogen is fed, wherein the molar ratio of hydrogen to polyunsaturated hydrocarbon is not greater than 1, characterized in that The heterogeneous catalyst used in the process comprises palladium and platinum as catalytically active metals, wherein the catalyst has a palladium concentration of at most 2.0 wt. %, a platinum concentration of at most 1.0 wt. %, and a total metal dispersion of at least 70%.

7. The method according to claim 6, characterized in that The higher diene is a C5 diene.

8. The method according to claim 7, characterized in that The higher diene olefin is isoprene.

9. The method according to any one of claims 6 to 8, characterized in that: The mercaptan is thioetherified with a polyunsaturated hydrocarbon, wherein the polyunsaturated hydrocarbon is selected from the group consisting of 1,3-butadiene, but-3-ene-1-yne and 1,2-butadiene.

10. The method according to any one of claims 6 to 8, characterized in that: At least ethanethiol and / or methyl mercaptan are present as mercaptans.

11. The method according to any one of claims 6 to 8, characterized in that: The molar ratio of hydrogen to polyunsaturated hydrocarbon is between 0.01 and 0.

8.

12. The method according to claim 11, characterized in that The molar ratio of hydrogen to polyunsaturated hydrocarbon is between 0.1 and 0.

5.

13. The method according to any one of claims 6 to 8, characterized in that: It is carried out in the presence of carbon monoxide, wherein the carbon monoxide content in the reactor feed is less than 20 ppm, based on the mass of the feed.

14. The method according to any one of claims 6 to 8, characterized in that: The inlet temperature of the reactor feed was between 0°C and 180°C.

15. The method according to claim 14, characterized in that The inlet temperature of the reactor feed was between 60°C and 150°C.

16. The method according to claim 14, characterized in that The inlet temperature of the reactor feed was between 80°C and 130°C.

17. The method according to any one of claims 6 to 8, characterized in that: It operates in a liquid phase process, and hydrogen is completely dissolved in the liquid phase.

18. The method according to any one of claims 6 to 8, characterized in that: A C4 hydrocarbon stream is used as feed to the reactor.

19. The method according to any one of claims 6 to 8, characterized in that: If the concentration of 1-butene in the hydrocarbon stream is above the concentration at which the double bond of 1-butene is isomerized to 2-butene at thermodynamic equilibrium, the conversion of 1-butene by isomerization to 2-butene and / or hydrogenation to n-butane is less than 5%.

20. The method according to claim 19, characterized in that If the concentration of 1-butene in the hydrocarbon stream is higher than the concentration at which the double bond of 1-butene is isomerized to 2-butene at thermodynamic equilibrium, the conversion of 1-butene by isomerization to 2-butene and / or hydrogenation to n-butane is less than 3%.

21. The method according to claim 19, characterized in that If the concentration of 1-butene in the hydrocarbon stream is higher than the concentration at which the double bond of 1-butene is isomerized to 2-butene in thermodynamic equilibrium, the conversion of 1-butene by isomerization to 2-butene and / or hydrogenation to n-butane is less than 2%.

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