Filtering material and method for desulphurising hydrocarbons and use of said filtering material

Abstract

The present invention relates to a filtering material comprising a mixture of amorphous silica (SiO₂) and amorphous graphitic carbon (C), wherein the content of graphitic carbon (C) ranges from 15 to 25 wt.-% in the mixture, with a particle size of less than 0.6 mm.

Description

[0001] FILTER MATERIAL AND METHOD FOR THE DESULFURATION OF HYDROCARBONS AND USE OF SAID FILTER MATERIAL

[0002] DESCRIPTION

[0003] Technical sector

[0004] The present invention describes a filter material used in hydrocarbon purification and separation processes, specifically the separation of non-aqueous, low-polarity liquids in the hydrocarbon chemical industry and refineries. It also describes a method for hydrocarbon desulfurization and the use of this filter material. Advances in desulfurization techniques are fundamental for the petrochemical and energy industries, since hydrocarbon-derived fuels, such as diesel, naphtha, and gasoline, contain sulfur compounds that must be removed to comply with environmental regulations and improve the efficiency of industrial processes.

[0005] Background of the state of the art

[0006] Fuel desulfurization has become a critical environmental issue that must be addressed for the global benefit. During combustion, the sulfur present in fuels generates sulfur oxides (SOx), which not only contribute to acid rain but also damage the catalysts responsible for reducing emissions of carbon monoxide (CO) and nitrogen oxides (NOx). Furthermore, the adoption of new, high-efficiency fuel technologies, such as direct-injection internal combustion engines and ocean-going vessels, requires compliance with international regulations, such as the IMO 2020 sulfur limit, which sets a maximum of 0.5% by weight.

[0007] Currently, several industrial methods exist to reduce the sulfur content in petroleum products such as diesel and gasoline. Among the most common are hydrotreating (HDS), the most widely used process, which involves reacting sulfur compounds with hydrogen in the presence of catalysts at high temperatures and pressures. The catalysts, generally metal oxides or noble metals, convert the sulfur compounds into hydrogen sulfide (H₂S), which is easier to remove. There is also selective hydrodesulfurization (SDH), a method focused on removing sulfur compounds that are difficult to treat using conventional hydrotreating, such as refractory sulfur compounds. Enzymatic desulfurization (EDS) uses enzymes to catalyze desulfurization, making it a more selective and less energy-intensive process than other traditional methods.Absorption, on the other hand, uses absorbent materials, such as zeolites, to capture sulfur compounds, allowing the absorbent to be regenerated by desorption once saturated. Another method is extraction, which employs selective solvents to separate sulfur compounds before hydrocarbons are used as fuels. Oxidation converts sulfur compounds into sulfur dioxide (SO2), facilitating their removal in gas treatment processes. Finally, ionic liquids, which are liquid salts at room temperature, offer promising properties for capturing and removing sulfur from hydrocarbons.

[0008] It is important to note that the choice of desulfurization process depends on multiple factors, such as the type of crude oil, the product composition, and the quality standards required for the final product. Furthermore, the petroleum industry is constantly evolving, driving the development of new processes and technologies that optimize efficiency and reduce environmental impact.

[0009] The inventors of the present invention have developed an innovative filter material composed primarily of amorphous silica and amorphous graphite carbon, with an amorphous graphite carbon content ranging from 15% to 25% by weight in the mixture. This material is effective in separating hydrocarbons with different organic compounds through filtration processes. One of its most notable applications is the desulfurization of hydrocarbons in industrial settings, such as the treatment of diesel fuels, where it allows the removal of sulfur compounds at ambient temperature and low pressures. Furthermore, the granular structure of the filter material facilitates its regeneration, making it an efficient and sustainable solution for fuel purification.

[0010] Hydrocarbon desulfurization has been the first field of application for the filter material of the present invention, beginning with the purification of gas oils. The simplicity of the initial preparation of the filter material and its regeneration for subsequent use represents a significant advantage for its implementation in industrial desulfurization processes.

[0011] In the case of diesel desulfurization, the proposed process is based on filtration through a granular material, similar to that used in swimming pool filters, but adapted to the specific needs of desulfurization. This method is distinguished by its low energy consumption, making it a sustainable and environmentally friendly option.

[0012] When comparing the present invention with other desulfurization methods available in the prior art, numerous significant advantages are identified, which are detailed below:

[0013] Hydrotreating is known for its high energy consumption, due to the high temperatures and pressures required to carry out the chemical reactions, as well as the need to supply hydrogen.The main factors contributing to this high consumption are heating, as high temperatures are required to activate the catalysts and promote the desulfurization reactions, which implies a considerable energy expenditure in heating and maintaining the reactors; pressure, since the reaction is carried out at high pressures to maximize efficiency and the production of desulfurized products; compression and recycling of hydrogen needed for the process; catalyst regeneration, as catalysts degrade over time and require additional heating and cooling cycles; and the treatment of effluents generated during the process, which may require additional treatment to comply with environmental standards, implying extra energy use.Due to this high energy demand, hydrotreating desulfurization processes are often subject to optimization efforts to reduce energy consumption and improve efficiency.

[0014] Selective hydrodesulfurization, while effective, also exhibits high energy consumption compared to the filtration process using the filter material of the present invention. On the other hand, enzymatic hydrodesulfurization has the potential to be more energy-efficient than conventional methods. However, its development and application are still ongoing, requiring further research to evaluate its technical and economic feasibility in an industrial context.

[0015] Desulfurization by adsorption using zeolites is limited compared to other conventional methods, such as hydrodesulfurization. Although the adsorption process does not require a large amount of energy in terms of heat and pressure, the regeneration of zeolites saturated with sulfur compounds involves the application of heat, which can increase overall energy consumption. Furthermore, the production and regeneration costs of zeolites limit their economic viability on an industrial scale.

[0016] Regarding selective solvent extraction, the choice of solvent depends on several factors, such as the types of sulfur compounds present and the solvent's regeneration capacity. However, the need to regenerate solvents laden with sulfur compounds can lead to additional energy consumption. In contrast, the filtration process of the present invention does not face these challenges.

[0017] Desulfurization by oxidation to sulfur dioxide (SO2) may require a significant amount of energy for heating and preparation of the reactors, although it may be less energy intensive than hydrotreating.

[0018] Finally, ionic liquid desulfurization processes, while promising due to their unique properties, are still in the research stages. The technical and economic feasibility of industrial-scale ionic liquid desulfurization remains under evaluation and may vary depending on specific conditions and the types of sulfur compounds present.

[0019] In conclusion, the low energy consumption of the desulfurization process using the filtration method with the filter material of the present invention is not only more efficient, but also contributes to environmental sustainability in industrial processes, representing a clear advantage over the options available in the prior art.

[0020] A primary objective of the present invention is to disclose a filter material characterized by being composed of a mixture of amorphous silica (SiO2) and amorphous graphite carbon (C), where the content of amorphous graphite carbon (C) varies between 15% and 25% by weight in the mixture, and with a particle size of less than 0.6 mm. The percentage ratio between amorphous silica and amorphous graphite carbon used defines the type of separation to be performed.

[0021] In the present invention, the term amorphous silica refers to a form of silicon dioxide (SiO2) that, unlike crystalline silica, does not have an ordered, repeating crystalline structure. In amorphous silica, the silicon and oxygen atoms are arranged in a disordered manner, which gives it physical and chemical properties distinct from crystalline varieties such as quartz.

[0022] In the present invention, the term amorphous graphite carbon refers to a form of carbon that, while sharing some characteristics with graphite, does not have an ordered crystalline structure. Instead of having stacked sheets of carbon atoms in a hexagonal arrangement, like crystalline graphite, amorphous graphite carbon has a disordered structure, which gives it distinctive properties.

[0023] In the present invention, granulometry refers to the particle size of the filter material. Specifically, it indicates that the particles of the amorphous silica and amorphous graphite carbon mixture are smaller than 0.6 mm. Granulometry is a key property in filtration materials, as it influences filtration efficiency and particle retention capacity.

[0024] Preferably, the silicon (Si) content in the mixture is between 30% and 40% by weight.

[0025] Preferably, the oxygen (O) content in the mixture is between 35% and 45% by weight. Preferably, the filter material has an average porosity of between 0.30 and 0.60 µm. 3 / g. More preferably, the filter material has an average porosity of 0.45 m 3 / g.

[0026] In the present invention, porosity refers to the volume of pores present in the filter material relative to its mass. It is expressed in units of cubic meters per gram (m³). 3 / g), which indicates the amount of empty space within the material that can accommodate or retain liquids or gases.

[0027] Preferably, the filter material has an average apparent density of between 0.30 and 0.65 kg / l. More preferably, the filter material has an average apparent density of between 0.45 and 0.5 kg / l.

[0028] In the present invention, the apparent average density refers to the mass of the filter material per unit volume, including both solids and voids (pores) within the material. It is expressed in kilograms per liter (kg / l) and represents an overall measure of how compact or lightweight the filter material is, taking into account its porous structure.

[0029] Preferably, the filter material is regenerable and recyclable.

[0030] To regenerate the filter material after its use in filtering hydrocarbons containing organosulfur compounds, it undergoes heat treatment in an inert nitrogen atmosphere, with temperatures ranging from ambient to 500 °C. During this process, the organic compounds retained in the filter are removed, allowing the material to be regenerated and returned to optimal condition for reuse.

[0031] A second objective of the present invention is to disclose a method for desulfurizing hydrocarbons characterized in that it comprises the following steps: a) Preparing a filter material composed of a mixture of amorphous silica (SiO2) and amorphous graphite carbon (C), wherein the content of amorphous graphite carbon (C) varies between 15% and 25% by weight in the mixture, and whose particle size is less than 0.6 mm; b) subjecting the hydrocarbons to a filtration process using said filter material, wherein the filtration is carried out at a temperature between 18 e C and 27 e C already a pressure between 1 kg / cm 2 and 4 kg / cm 2 c) separating sulfur compounds present in hydrocarbons through the interaction between the amorphous silica and amorphous graphite carbon phases; d) regenerating the filter material for reuse in subsequent filtration processes; and e) recovering the desulfurized hydrocarbons after the filtration process.

[0032] A third objective of the present invention is to disclose the use of the filter material in hydrocarbon filtration for the separation of compounds with different organic functions, especially in industrial applications.

[0033] Preferably, the hydrocarbons to be filtered are liquids with a high sulfur content, such as diesel, naphtha and gasoline.

[0034] Description of the figures

[0035] Figure 1 shows a photomicrograph of backscattered electrons at different magnifications.

[0036] Figure 2 shows a backscattered electron micrograph taken by scanning electron microscopy (SEM) indicating four points to be analyzed by Energy Dispersive X-ray Spectroscopy (EDX).

[0037] Figure 3 is a graph of Energy Dispersive X-ray Spectra (EDX) of the four analyzed grains corresponding to Figure 2.

[0038] The inventors of the present invention determined the silicon-to-carbon ratio of the filter material. This ratio is established as Si (34.8%), O (40.6%), and C (20.6%), expressed as a percentage by weight. The composition was determined using various methods, including Solid and Surface Analysis and Characterization (SACSS), X-ray Diffraction (XRD), X-ray Fluorescence (WDXRF), and Scanning Electron Microscopy (SEM-EDX). Furthermore, Elemental Analysis, Raman Spectroscopy, and Infrared Spectroscopy tests were conducted at the Elemental and Molecular Analysis Service (SAEM), leading to the following conclusions:

[0039] - Infrared Spectroscopy revealed the presence of amorphous silica (SiO2), a finding that coincides with the results obtained by X-ray Diffraction.

[0040] - The results of the Raman Spectroscopy indicated that the carbon present in the sample has a non-crystalline (amorphous) structure.

[0041] - Through Scanning Electron Microscopy, two different types of grains or particles were observed, which, according to their analysis by Energy Dispersive X-rays, appear to correspond to the two phases detected: SiO2 and C.

[0042] Finally, the morphological characterization of the sample was performed using a Scanning Electron Microscope (SEM) equipped with Energy Dispersive X-ray Spectroscopy (EDX), as shown in Figures 1 and 2. Images were obtained at different magnifications using a backscattered electron detector. This type of imagery not only provides morphological information about the size and shape of the particles but also offers data on their composition. The contrast in these images is determined by the sample composition: darker tones correspond to lighter elements, while lighter tones are associated with heavier elements. In the micrographs of Figures 1 and 2, two types of grains are observed, differentiated by their gray hue, indicating that the sample is composed of a mixture of two distinct phases.

[0043] Figure 1 is a backscattered electron micrograph showing three images obtained by scanning electron microscopy (SEM), revealing fragmented materials of varying sizes and textures. In the upper left image, irregular particles and fragments of different sizes are distributed across a surface. The fragments vary in shape, some angular and others smoother, and appear to be made of different materials. The scale indicates 500 pm, suggesting that these particles are on the order of hundreds of micrometers. The upper right image is a zoom of a region from the previous image, marked with a red box. Here, the characteristics of the fragments are shown in greater detail. The main fragment appears darker and rougher compared to the adjacent, smoother fragments. The scale of this image is 100 pm. The lower image shows more isolated particles on the surface.The large fragment in the center left has a rough texture, while the lighter fragments on the right are more angular and smooth. The scale of this image is 200 pm.

[0044] Figure 2 is a backscattered electron micrograph taken using scanning electron microscopy (SEM). The image shows various fragments and particles of different sizes and shapes distributed across a surface. Figure 2 shows a qualitative elemental analysis using Energy Dispersive X-ray Spectroscopy (EDX) of different grains, revealing that the lighter-colored grains (points 1 and 2) have a high silicon and oxygen content, while the darker grains (points 3 and 4) have a higher percentage of carbon.

[0045] Figure 3 contains four Energy Dispersive X-ray Spectra (EDX) spectra, corresponding to four different analysis points (point 1, point 2, point 3, and point 4). This type of spectrum is used to identify the elemental composition of the analyzed materials.

[0046] Spectrum of point 1: The graph shows significant peaks corresponding to elemental vapors. The most prominent peaks are located between 0 and 2 keV, suggesting the presence of elements that emit X-rays at these energies, possibly light or intermediate elements. Labeled vapor peaks are identified, likely assigned to elements such as carbon (C), oxygen (O), aluminum (Al), silicon (Si), etc.

[0047] Spectrum of point 2: Similar to point 1, this spectrum also exhibits marked peaks around 0-2 keV. However, the distribution and intensity of the peaks appear slightly different, suggesting a variation in elemental composition compared to point 1. The identified elements are likely the same or similar, but with different concentrations or intensities.

[0048] Spectrum of point 3: This spectrum shows a different peak pattern compared to the previous two. A higher peak in the 0 keV region is notable, suggesting the possible predominance of a different element or a greater quantity than in the other points. Again, labels identifying vapor elements can be observed, indicating a complex composition.

[0049] Spectrum of point 4: This spectrum looks very similar to the Spectrum of point 3.

[0050] Examples

[0051] Example 1:

[0052] The diesel underwent a pre-oxidation treatment, which reduced the sulfur content from 2500 ppm to 510 ppm in a first filtration using the filter material of the present invention. In a second filtration, the sulfur content was further reduced to 95 ppm. The ratio used was 1 g of filter material per 10 g of diesel. As a result, a diesel fuel was obtained that complies with the MGO 2020 standard, making it suitable for use in ocean navigation due to its low sulfur content.

[0053] Example 2:

[0054] In a filtration process without prior oxidation treatment, a 1:10 weight ratio (filter material of the present invention: diesel) was used, filtering 85.6 g of diesel with an initial sulfur content of 3100 ppm over 8.4 g of granulated sand of the filter material of the present invention. In the first filtration, the sulfur content was reduced to 2446 ppm, representing a 12.67% decrease in sulfur content.

[0055] Example 3:

[0056] A pre-oxidation treatment was carried out on the organic sulfur compounds present in the diesel. In this case, 8.4 g of the filter material of the present invention were treated with 100 g of diesel containing 3100 ppm of sulfur. After the first filtration, the sulfur content in the filtered diesel was reduced to 623 ppm, thus achieving a 79.9% reduction in sulfur content.

[0057] Additionally, using the same diesel with 3100 ppm sulfur, 400 g of diesel were filtered through 33.6 g of sand from the filter material of the present invention, obtaining diesel with 600 ppm sulfur. The reduction in sulfur content was 80%.

[0058] Although the invention has been described with respect to examples of preferred embodiments, these should not be considered limiting to the invention, which will be defined by the broadest interpretation of the following claims.

Claims

CLAIMS 1. Filter material characterized in that it is composed of a mixture of amorphous silica (SiO2) and amorphous graphite carbon (C), in which the content of amorphous graphite carbon (C) varies between 15% and 25% by weight of the mixture, and with a granulometry of less than 0.6 mm.

2. Filter material, according to claim 1, characterized in that the silicon (Si) content in the mixture is between 30% and 40% by weight.

3. Filter material, according to any of the preceding claims, characterized in that the oxygen (O) content in the mixture is between 35% and 45% by weight.

4. Filter material, according to any of the preceding claims, characterized in that the filter material has an average porosity of between 0.30 and 0.60 m 3 / g.

5. Filter material, according to claim 4, characterized in that the filter material has an average porosity of 0.45 m 3 / g.

6. Filter material, according to any of the preceding claims, characterized in that the filter material has an apparent average density of between 0.30 and 0.65 kg / l.

7. Filter material, according to claim 6, characterized in that the filter material has an apparent average density of between 0.45 and 0.5 kg / l.

8. Filter material according to any of the preceding claims, characterized in that it is regenerable and recyclable.

9. Method for the desulfurization of hydrocarbons, characterized in that it comprises the following steps: a) Preparing a filter material composed of a mixture of amorphous silica (SiO2) and amorphous graphite carbon (C), in which the carbon (C) content amorphous graphite varies between 15% and 25% by weight in the mixture, and whose particle size is less than 0.6 mm, according to any of claims 1 to 8; b) subjecting the hydrocarbons to a filtration process using said filter material, wherein the filtration is carried out at a temperature between 18 e C and 27 e C already a pressure between 1 kg / cm 2 and 4 kg / cm 2 c) separating sulfur compounds present in hydrocarbons through the interaction between the amorphous silica and amorphous graphite carbon phases; d) regenerating the filter material for reuse in subsequent filtration processes; and e) recovering the desulfurized hydrocarbons after the filtration process.

10. Use of the filter material, according to any of the preceding claims, in the filtration of hydrocarbons for the separation of compounds with different organic functions, especially in industrial applications.

11. Use of the filter material, according to any of the preceding claims, wherein the hydrocarbons are liquids with a high sulfur content.

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