Process for oxidation of organosulfur compounds
11149209 · 2021-10-19
Assignee
Inventors
- Manuel Arturo López Quintela (Santiago de Compostela-A Coruna, ES)
- David Buceta Fernández (Santiago de Compostela-A Coruna, ES)
Cpc classification
B82Y30/00
PERFORMING OPERATIONS; TRANSPORTING
International classification
Abstract
The present invention refers to process for oxidation of organosulfur compounds comprising metal AQCs having between 5 and 13 metal atoms as catalyst. Additionally, the present invention refers to the use of the metal AQCs having between 5 and 13 metal atoms as catalyst in the oxidation of organosulfur compounds and to a chemical composition comprising organosulfur compounds and metal AQCs having between 5 and 13 metal atoms.
Claims
1. A process for oxidation of an organosulfur compound comprising the following steps: i) providing a catalyst comprising metal Atomic Quantum Clusters (AQCs) consisting of between 5 and 13 metal atoms; wherein the metal of the metal Atomic Quantum Clusters (AQCs) is selected from Ag, Co, Cu, Pt, Fe, Pd, Ni or their bi-metal and multi-metal combinations; and ii) contacting the catalyst of step (i) with an organosulfur compound to oxidize said organosulfur compound; wherein the contacting of step (ii) is performed in a liquid having oxygen dissolved; wherein the step (ii) is performed at room temperature and atmospheric pressure; and wherein the organosulfur compound is selected from sulfur-containing heterocyclic chemical compounds, asphaltenes and mixtures thereof.
2. A process for oxidation of an organosulfur compound as defined in claim 1, wherein the metal of the metal AQCs is selected from Ag, Cu and combinations thereof.
3. A process for oxidation of an organosulfur compound as defined in claim 1, wherein the metal AQCs have 5 metal atoms.
4. A process for oxidation of an organosulfur compound as defined in claim 1, wherein the metal AQCs is supported in a support material.
5. A process for oxidation of an organosulfur compound as defined in claim 1, wherein the contacting step (ii) is performed by mixing the catalyst and the organosulfur compound in a solvent or in a mixture of solvents.
6. A process for oxidation of an organosulfur compound as defined in claim 1, wherein the contacting step (ii) is performed by passing the organosulfur compound dispersed in a solvent through the catalyst, wherein the catalyst comprises the metal AQCs supported in a support material.
7. A process for oxidation of an organosulfur compound as defined in claim 1, wherein the organosulfur compound of step (ii) is comprised within a hydrocarbon mixture.
8. A process for oxidation of an organosulfur compound as defined in claim 1, wherein the organosulfur compound is selected from thiophene, bithiophene, thienothiophene, benzothiophene, dibenzothiophene, tetrabenzothiophene, polythiophene, phenylthiophene, tetraphenylthiophene, thianthrene, dibenzyl sulfide, phenyl sulfide, phenyl disulfide, asphaltenes and mixtures thereof.
9. A process for oxidation of an organosulfur compound as defined in claim 1, wherein a sulfate is formed as a result of the oxidation of the organosulfur compound of step (ii).
10. A process for oxidation of an organosulfur compound as defined in claim 1, wherein the catalyst of step (i) is a homogeneous catalyst in dispersion.
Description
FIGURES
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DETAILED DESCRIPTION OF THE INVENTION
(7) Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood to one of ordinary skill in the art to which this disclosure belongs.
(8) As defined above, in a first aspect, the present invention refers to a process for oxidation of an organosulfur compound comprising the following steps:
(9) i) providing a catalyst comprising metal Atomic Quantum Clusters (AQCs) having between 5 and 13 metal atoms; wherein the metal of the metal Atomic Quantum Clusters (AQCs) is selected from Ag, Co, Cu, Pt, Fe, Pd, Ni or their bi-metal and multi-metal combinations; and
(10) ii) contacting the catalyst of step (i) with an organosulfur compound to oxidize said organosulfur compound; wherein the contacting of step (ii) is performed in a liquid having oxygen dissolved.
(11) In the context of the present invention, the term “organosulfur compound” or “organic sulfur compound” refers to an organic compound that contains sulfur naturally present for example within fossil fuels, coal, petroleum and natural gas. As define above, their removal is a major focus of oil refineries. The most common organosulfur compounds present in all crude oil fractions are thiophene (C.sub.4H.sub.4S)-based compounds and asphaltenes. Non-limiting examples of organosulfur compounds suitable for the process of the present invention are thiol derivatives, sulfur-containing heterocyclic chemical compounds such as thiophene-based compounds, thianthrene, dibenzyl sulfide, phenyl sulfide and phenyl disulfide, asphaltenes and/or mixtures thereof; preferably thiol derivatives, thiophene-based compounds, thianthrene, dibenzyl sulfide, phenyl sulfide, phenyl disulfide, asphaltenes and/or mixtures thereof; more preferably thiophenol, thiophene, bithiophene, thienothiophene, benzothiophene, dibenzothiophene, tetrabenzothiophene, polythiophene, phenylthiophene, tetraphenylthiophene, thianthrene, dibenzyl sulfide, phenyl sulfide, phenyl disulfide, asphaltene and/or mixtures thereof; even more preferably dibenzothiophene, tetrabenzothiophene, asphaltene, thiantrene and/or mixtures thereof.
(12) In a particular embodiment, the organosulfur compound used in the process of the present invention is selected from thiol derivatives, sulfur-containing heterocyclic chemical compounds, asphaltenes and mixtures thereof; more preferably from sulfur-containing heterocyclic chemical compounds, asphaltenes and mixtures thereof; more preferably from thiophenol, thiophene, bithiophene, thienothiophene, benzothiophene, dibenzothiophene, tetrabenzothiophene, polythiophene, phenylthiophene, tetraphenylthiophene, thianthrene, dibenzyl sulfide, phenyl sulfide, phenyl disulfide, asphaltenes and mixtures thereof.
(13) In a more particular embodiment, the organosulfur compound used in the process of the present invention is selected from thiophene-based compounds, thiantrene, asphaltenes and mixtures thereof; preferably from thiophene-based compounds, asphaltenes and mixtures thereof.
(14) The term “thiophene-based compounds” refers to a family of organic compounds having the thiophene structure included in their organic skeleton and which comprises aliphatic, cyclic and aromatic derivates. The term “thiophene” refers to a heterocyclic compound with the formula C.sub.4H.sub.4S also commonly called thiofuran.
(15) Non limiting examples of thiophene-based compounds suitable in the process of the present invention include thiophene, bithiophene, thienothiophene, benzothiophene, dibenzothiophene, tetrabenzothiophene, polythiophene, phenylthiophene and tetraphenylthiophene.
(16) In a particular embodiment thiophene-based compounds suitable in the process of the present invention are selected from thiophene, bithiophene, thienothiophene, benzothiophene, dibenzothiophene, tetrabenzothiophene, polythiophene, phenylthiophene and tetraphenylthiophene; preferably selected from thiophene, dibenzothiophene, tetrabenzothiophene and tetraphenylthiophene.
(17) The term “asphaltenes” refers to molecular substances that are found in crude oil, along with resins, aromatic hydrocarbons, and saturates (i.e. saturated hydrocarbons such as alkanes). Asphaltenes consist primarily of carbon, hydrogen, nitrogen, oxygen, and sulfur, as well as trace amounts of vanadium and nickel. The C:H ratio is approximately 1:1.2, depending on the asphaltene source. Asphaltenes are defined operationally as the n-heptane-insoluble, toluene-soluble component of a carbonaceous material such as crude oil, bitumen, or coal. Asphaltenes have been shown to have a distribution of molecular masses in the range of 400 u to 1500 u, but the average and maximum values are difficult to determine due to aggregation of the molecules in solution.
(18) The process for oxidation of an organosulfur compound of the present invention comprises a step (i) of providing a catalyst comprising metal Atomic Quantum Clusters (AQCs) having between 5 and 13 metal atoms.
(19) The term “Atomic Quantum Cluster”, abbreviated as AQC, is understood as metal Atomic Quantum Cluster. Metal AQCs are formed exclusively by zero-oxidation-state metal atoms, M.sub.n, with less than approximately 200 metal atoms (M.sub.n, n<200), and with a size of less than 2 nm. The AQCs are stable over time. In addition, AQCs are known for no longer behaving like a “metal” and their behavior becomes molecular like. Therefore, new properties which are not observed in nanoparticles, microparticles or bulk metal appear in these clusters. Therefore, the physical-chemical properties of the AQC cannot be simply extrapolated from those of the nano/microparticles.
(20) Metal AQCs suitable in the process of the present invention are further characterized by being made up of less than 200 metal atoms (M.sub.n, n<200), preferably less than 100 metal atoms (M.sub.n, n<100), more preferably between 5 and 13 metal atoms (M.sub.n, 5≤n≤13) even more preferably 5 metal atoms (M.sub.n, n=5).
(21) The metal AQCs used in the process of the present invention are synthesized according to the process described in patent ES2277531, its corresponding WO 2007/017550 A1 and in documents N. Vilar-Vidal et al. [N. Vilar-Vidal et al. Small 2014, 10, No. 18, 3632-3636] and Huseyinova S. et al. [Huseyinova S. et al. J. Phys. Chem. C 2016, 120, 15902-15908]. The method for obtaining metal AQCs described in said documents are based on reduction of the salt or metal ion (metal salts or ions) while maintaining a kinetic control for a slow reduction and a low concentration of reagents in the reaction medium. Thus, the clustering formation is not limited to the type of synthesis, or the metallic element, for which reason any other chemical method of reduction of metal salts in solution can be used for the production of these AQCs, provided that the reaction slowdowns later enough as to observe the evolution of the AQC and stop the reaction (eg. by cooling, dilution and/or fixation/separation of the clusters of the reaction medium) at the time that interests one AQC of a determined size.
(22) The metals of the metal AQCs suitable in the process of the present invention are transition metals, preferably the metals are selected from Au, Ag, Co, Cu, Pt, Fe, Pd, Ni or their bi-metal and multi-metal combinations, the metals are selected from Ag, Co, Cu, Pt, Fe, Pd, Ni or their bi-metal and multi-metal combinations, even more preferably are selected from Ag, Cu and a combination thereof. In a particular embodiment, the metals of the metal AQCs suitable in the process of the present invention are Ag or Cu.
(23) The authors of the present invention has surprisingly observed that metal AQCs having between 5 and 13 metal atoms can completely oxidize the most difficult to oxidize organosulfur compounds, i.e., thiophene-based compounds and asphaltenes, to compounds of sulfur oxidation state +6.
(24) Without being bound to any theory in particular it is believed that the surprising catalytic activity of AQCs as oxidation catalyst of organosulfur compounds is due to the oxygen adsorption and activation by the clusters, but detailed theoretical calculations, including the presence of solvent and oxygen, are needed to fully understand such exceptional catalytic activities.
(25) In a preferred embodiment, the metal AQCs are monodispersed metal AQCs, more preferably monodispersed metal AQCs having 5 metal atoms, even more preferably the metal AQCs are monodispersed metal AQCs having 5 metal atoms with the exception of monodispersed Au AQCs having 5 metal atoms.
(26) In addition, the metal AQCs as defined above can be provided as homogenous catalyst in dispersion, or as heterogeneous catalyst wherein the metal AQCs are supported in a support material.
(27) As a non-limiting example, the metal AQCs supported on a support material can be prepared just by dropping the corresponding AQCs solution onto the support and left drying. The drying process can be alternatively done under vacuum to accelerate the process. Other standard supporting methods well-known in the technical field of the present invention can be also used such as spin coating an AQC solution onto planar substrates.
(28) Non-limiting examples of suitable supports include carbon black, graphite, mesoporous carbon, graphene, graphene oxide, glassy carbon, silicium oxide, mesoporous silica, cerium oxide, titanium oxide, tin oxide, manganese oxide, zinc oxide, zirconium oxide, aluminium oxide, iron oxide, nickel oxide, cobalt oxide, zeolites, polytetrafluorethylene, polyethylene, reinforced plastics, steel and combinations thereof.
(29) In a preferred embodiment, the support material is a solid with a high surface area.
(30) In another preferred embodiment, the support material is graphite, more preferably porous graphite.
(31) The process the present invention further comprises a step (ii) of contacting the catalyst of step (i) with the organosulfur compound to oxidize said organosulfur compound.
(32) The expression “contacting” of step (ii) refers to a physical contact between the catalyst and the organosulfur compound.
(33) In a particular embodiment, the contacting of step (ii) is performed in a liquid having oxygen dissolved. In the context of the present invention the term “liquid” refers to a solvent, a mixture of solvents or an organosulfur compound, suitable for the process of the present invention, in liquid phase having oxygen dissolved.
(34) In a more particular embodiment, the contacting of step (ii) is performed in a solvent or in a mixture of solvents; preferably in a solvent or in a mixture of solvents having oxygen dissolved; more preferably in a solvent or in a mixture of solvents having oxygen dissolved at atmospheric pressure and at room temperature.
(35) In a preferred embodiment, the contacting of step (ii) is performed in liquid phase having oxygen dissolved in a concentration of between 0.1 and 30 mg/l at room temperature and atmospheric pressure; preferably between 1 and 20 mg/l at room temperature and atmospheric pressure. In the context of the present invention the expression “room temperature” refers to what is commonly understood by an expert in the art.
(36) The process for oxidation of an organosulfur compound of the present invention works at atmospheric pressure and room temperature, but, if necessary, oxygen pressure may be added to the solvent or mixture of solvents suitable for the process of the present invention by commonly known means in the art such as by introducing pressurized oxygen, preferably by introducing between 1 and 10 bars of pressurized O.sub.2; more preferably by introducing between 3 and 7 bars of pressurized O.sub.2; even more preferably by introducing about 5 bars of pressurized O.sub.2.
(37) In a more particular embodiment, the contacting of step (ii) is performed in a solvent or in a mixture of solvents having oxygen dissolved; wherein the oxygen dissolved has reached at least a 40% oxygen saturation, preferably at least a 70% oxygen saturation, more preferably at least a 90% oxygen saturation, even more preferably a 100% oxygen saturation. The oxygen saturation suitable for the process of the present invention can be achieved at a certain pressure and temperature by means commonly known by the expert in the art such as applying oxygen pressure.
(38) In the context of the present invention the expression “oxygen saturation” refers to a relative measure of the concentration of oxygen that is dissolved or carried in a given liquid medium, such a solvent or a mixture of solvents, as a proportion of the maximal concentration that can be dissolved in that medium at a certain temperature and pressure, usually at room temperature and at atmospheric pressure and it is generally expressed as a percentage (%). It may be measured with a dissolved oxygen probe such as an oxygen sensor.
(39) In even a more particular embodiment the contacting step (ii) is performed at room temperature and at atmospheric pressure. In a particular embodiment, the catalyst in step (ii) is used as homogenous catalyst in dispersion together with the organosulfur compound. Thus, in this particular embodiment, the contacting step (ii) is performed by physically mixing both the catalyst and the organosulfur compound in liquid phase by for example well-known mechanical devices, such as static mixers, rotor-stator systems, sonifiers and high-pressure homogenizers.
(40) In another particular embodiment, the catalyst in step (ii) is used as heterogeneous catalyst, preferably as a supported catalyst, i.e., the metal AQCs are supported in a support material as defined above. Thus, in this particular embodiment, the contacting step (ii) is preferably performed by passing the organosulfur compound dispersed in a solvent through the metal AQCs supported in a support material.
(41) Non-limiting examples of solvents suitable in the above defined particular embodiments include water, tetrahydrofurane (THF), dimetilsulphoxide (DMSO), ether, toluene, acetonitrile (ACN), alkanes, halogenated alkanes, cycloalkanes, fuels and mixtures thereof, preferably water and THF-water and toluene-water mixtures.
(42) The authors of the present invention have surprisingly observed that after contacting as defined above the catalyst of step (i) with the organosulfur compound said organosulfur compound is effectively oxidized, particularly to sulfur oxidation states +4 (sulfones) and +6 (sulfates).
(43) In a preferred embodiment, a sulfate is formed as a result of the oxidation of the organosulfur compound of step (ii).
(44) In the context of the present invention, the term “sulfate” refers to either inorganic sulfate (SO.sub.4.sup.2−) or organic compounds in which one or two of the hydrogen atoms of sulfuric acid have been replaced by carbon-containing combining groups such as methyl (CH.sub.3) or ethyl (C.sub.2H.sub.5).
(45) In another preferred embodiment, the organosulfur compound of step (ii) is comprised within a hydrocarbon mixture, more preferably within petroleum or a petroleum-based fuel.
(46) In the context of the present invention, the term “hydrocarbon mixture” refers to a mixture of organic compounds which are the result of a cracking process in the field of petroleum chemistry whereby complex organic molecules such as kerogens or long chain hydrocarbons are broken down into simpler molecules such as light hydrocarbons, by the breaking of carbon-carbon bonds in the precursors. The rate of cracking and the end products are strongly dependent on the temperature and presence of catalysts. Cracking is the breakdown of a large alkane into smaller, more useful alkanes and alkenes. Simply put, hydrocarbon cracking is the process of breaking a long-chain of hydrocarbons into short ones. This process might require high temperatures and high pressure.
(47) The term “petroleum” refers to a naturally occurring, yellow-to-black liquid found in geological formations beneath the Earth's surface, which is commonly refined into various types of fuels. Components of petroleum are separated using a technique called fractional distillation. It consists of hydrocarbons of various molecular weights and other organic compounds such as organosulfur compounds. In the context of the present invention, term “petroleum” covers both naturally occurring unprocessed crude oil and petroleum products which are made up of refined crude oil, such as petroleum based-fuels.
(48) The term “petroleum-based fuels” refers to the most common distillation fractions of petroleum and petroleum-derived products including, but not-limited to, naphtha, liquefied petroleum gas (LPG), butane, gasoline, jet fuel, kerosene, fuel oil and diesel fuel.
(49) Thus, in another aspect, the present invention refers to a chemical composition comprising an organosulfur compound and metal AQCs having between 5 and 13 metal atoms.
(50) In a particular embodiment, the chemical composition of the present invention comprises an organosulfur compound selected from thiol derivatives, sulfur-containing heterocyclic chemical compounds, asphaltenes and mixtures thereof, and metal AQCs having between 5 and 13 metal atoms; preferably the organosulfur compound is selected from sulfur-containing heterocyclic chemical compounds, asphaltenes and mixtures thereof; more preferably the organosulfur compound is selected from thiophenol, thiophene, bithiophene, thienothiophene, benzothiophene, dibenzothiophene, tetrabenzothiophene, polythiophene, phenylthiophene, tetraphenylthiophene, thianthrene, dibenzyl sulfide, phenyl sulfide, phenyl disulfide, asphaltenes and mixtures thereof; even more preferably the organosulfur compound is selected from dibenzothiophene, tetrabenzothiophene, asphaltene, thiantrene and mixtures thereof.
(51) In a particular embodiment, the organosulfur compound of the present invention is selected from thiophene-based compounds, thiantrene, asphaltenes and mixtures thereof; preferably from thiophene-based compounds, asphaltenes and mixtures thereof.
(52) In a preferred embodiment, the organosulfur compound of the chemical composition as defined above is comprised within a hydrocarbon mixture, more preferably within petroleum or a petroleum-based fuel.
(53) In another preferred embodiment, the catalyst and the organosulfur compound of step (ii) are in a weight ratio higher than 1.Math.10.sup.−4.
(54) In a preferred embodiment, the organosulfur compound of step (ii) is dispersed in a solvent.
(55) Non-limiting examples of solvents suitable in the process of the present invention include water, tetrahydrofurane (THF), dimetilsulphoxide (DMSO), ether, toluene, acetonitrile (ACN), alkanes, halogenated alkanes, cycloalkanes, fuels and mixtures thereof, preferably water and THF-water and toluene-water mixtures.
(56) In a preferred embodiment, the step (ii) of the process of the present invention is performed at room temperature and atmospheric pressure.
(57) This is an important advantage over the desulfurization methods of the prior art since normally harsh reaction conditions are needed so they often cause degradation of the fuel itself, thereby lowering the quality of the fuel and make the process expensive.
(58) As explained above, metal AQCs have surprisingly shown a great efficiency as oxidation catalyst of organosulfur compounds. In particular, metal AQCs having between 5 and 13 metal atoms can be used to completely oxidize the most difficult to oxidize organosulfur compounds to compounds having sulfur in oxidation state +6.
(59) Thus, in another aspect, the present invention is directed to the use of metal AQCs having between 5 and 13 metal atoms as catalyst in oxidation of organosulfur compounds.
(60) In a particular embodiment, the use of metal AQCs having between 5 and 13 metal atoms as catalyst in oxidation of organosulfur compounds; wherein the organosulfur compound is selected from thiol derivatives, sulfur-containing heterocyclic chemical compounds, asphaltenes and mixtures thereof; preferably the organosulfur compound is selected from sulfur-containing heterocyclic chemical compounds, asphaltenes and mixtures thereof; more preferably the organosulfur compound is selected from thiophenol, thiophene, bithiophene, thienothiophene, benzothiophene, dibenzothiophene, tetrabenzothiophene, polythiophene, phenylthiophene, tetraphenylthiophene, thianthrene, dibenzyl sulfide, phenyl sulfide, phenyl disulfide, asphaltenes and mixtures thereof; even more preferably the organosulfur compound is selected from dibenzothiophene, tetrabenzothiophene, asphaltene, thiantrene and mixtures thereof.
(61) In a particular embodiment, the organosulfur compound of the present invention is selected from thiophene-based compounds, thiantrene, asphaltenes and mixtures thereof; preferably from thiophene-based compounds, asphaltenes and mixtures thereof.
EXAMPLES
(62) The present invention will now be described by way of examples which serve to illustrate the construction and testing of illustrative embodiments. However, it is understood that the present invention is not limited in any way to the examples below.
Example 1. Oxidation of Dibenzothiophene Using Ag AQCs
(63) 5 μg of monodispersed Ag AQCs of 5 metal atoms dispersed in THF-water were mixed with 20 mg of dibenzothiophene.
Example 2. Oxidation of Tetrabenzothiophene Using Ag AQCs
(64) 5 μg of monodispersed Ag AQCs of 5 metal atoms dispersed in THF-water were mixed with 20 mg of tetrabenzothiophene.
Example 3. Oxidation of Dibenzothiophene Using Supported Ag AQCs
(65) 0.1 μg of monodispersed Ag AQCs of 5 metal atoms in water were dropped onto a porous graphite support and dried under vacuum. Then, 1 mg of dibenzothiophene dispersed in THF was passed through the Ag AQCs/graphite support.
Example 4. Oxidation of Asphaltene Using Supported Ag AQCs
(66) 5 μg of monodispersed Ag AQCs of 5 metal atoms were dispersed in toluene-water mixture together with 20 mg of asphaltene.
Example 5. Oxidation of Dibenzothiophene Using Cu AQCs
(67) 30 μg of monodispersed Cu AQCs of 5 metal atoms were dispersed in THF-water with 20 mg of dibenzothiophene.
Example 6. Oxidation of Thiantrene Using Cu AQCs
(68) 3.5 μg of monodispersed Cu AQCs of 5 metal atoms dispersed in THF-water were mixed with 20 mg of thiantrene.