Removal of contaminants from coal tar derived crude phenols

Abstract

A process for removing contaminants from coal-derived phenols is described. The process combines an extraction process with at least two adsorption zones containing adsorbents. Liquid-liquid extraction and acid-base extraction processes can be used. The adsorbents can be clays and / or zeolites. The process can be used to reduce organic nitrogen compounds and organic sulfur compounds to levels below 10 ppmw and produce a colorless product.

Description

Background of the Invention

[0002] Low-temperature and medium-temperature coal tar contains a large amount of valuable phenols, especially in distillation fractions below 300°C. Various physical and chemical methods can be used to extract phenolic mixtures (crude phenols) from distillation fractions, such as extraction with an aqueous sodium hydroxide solution followed by neutralization with a strong inorganic acid, selective solvent extraction, and adsorption using ion exchange resins.

[0003] Typically, low-temperature and medium-temperature coal tar has a nitrogen and sulfur content of less than or equal to 1.0%. The extraction methods described above effectively remove some organosulfur and organonitrogen compounds from crude phenols. Any remaining trace amounts of organosulfur and organonitrogen compounds in crude phenols must be removed because they act as catalyst poisons in downstream upgrading methods, such as the conversion of lower-value phenolic compounds into higher-value phenolic and aromatic compounds via catalytic dealkylation and alkyl transfer.

[0004] In industry, hydrotreating is the most common method for removing organic nitrogen and organic sulfur from oil. However, hydrotreating is not a selective method for removing nitrogen and sulfur. In addition to hydronitrogen removal (HDN) and hydrosulfurization (HDS), other methods are performed in parallel, including hydrodemetallization (HDM), hydrodeoxygenation (HDO), hydroaromatic removal (HAD), and olefin saturation. Of the most abundant heteroatoms (S, N, and O) in oil, nitrogen is the most difficult to remove by hydrotreating. Furthermore, both HDO and HDA destroy phenols. It is generally accepted that nitrogen is the most difficult to remove, and because hydrotreating destroys phenols, it is not a good method for removing nitrogen contaminants from phenols. "Simultaneous hydrodenitrogenation and hydrodeoxygenation of model compounds in a tricklebed reactor", Journal of Catalysis (1983), 81(2): 335-346; "Hydrorefining Coal-TarNaphthalene, Hydrogenolysis over cobalt molybdate catalyst removes impurities containing sulfur, oxygen, and nitrogen and yields a refined product of highpurity", Industrial and Engineering Chemistry, Vol. 53, No. 12, 1961, pp. 993-996; "Hydrotreatment of model compounds with catalysts of NiW / Al2O3 and NiWP / Al2O3 to simulate low temperature coal tar oil", RSC Adv., 2017, 7, 54512. Furthermore, the removal of sulfur contaminants from phenols by catalytic hydrodesulfurization (HDS) is not efficient because HDS is inhibited by phenols such as cresol."Catalytic hydrodeoxygenation: II.Interactions between catalytichydrodeoxygenation of m-cresol and hydrodesulfurization of benzothiophene anddibenzothiophene", Journal of Catalysis (1983), 80(1): 65-75.

[0005] Other methods have also been used to remove sulfur and / or nitrogen. For example, in GB 738177, phenols in coal tar distillates are extracted with an aqueous solution of alkali, and the resulting phenolate solution is purified by treatment with one or more of the following adsorbents: bleaching clay made from montmorillonite group clays (bleaching clay, bentonite, chlorite, bedesulfurite, and lithium montmorillonite (Mg-bentonite)), alumina, basic oxides, hydroxides, or carbonates of Fe, Mg, or Ca, obtained by heating the phenolate alkali residue with lime. After neutralization with acid, particularly CO2, phenols are obtained in a clear liquid form with an acceptable odor. No nitrogen contaminant removal is addressed.

[0006] Another method is described in US 2,247,523. Phenolic compounds are extracted from coal tar distillates into an aqueous sodium hydroxide solution. The resulting phenolate solution is then treated with adsorbents such as bleaching clay, diatomaceous earth, and activated carbon. The phenolate solution is treated with acids such as HCl, H₂SO₄, or CO₂ to release the phenols. The phenols remain colored or at least darken upon standing, especially under light, and in some cases have an unpleasant odor. The odor and color of the phenols are ultimately improved by adding a small amount of formaldehyde and subsequent vacuum distillation. No nitrogen or sulfur contaminant removal is involved.

[0007] US 2,744,938 describes a method for decolorizing alkylphenols that have undergone oxidation. The method involves contacting a solution of alkylphenols in a solvent with an adsorbent selected from activated carbon, alumina, clay, and silica gel at a temperature of about 40 to about 150°C in the presence of hydrogen under atmospheric pressure. The removal of nitrogen and sulfur contaminants is not addressed.

[0008] CN 102188962 discloses a catalytic adsorbent for refining coal-based phenols. The catalytic adsorbent comprises the following active ingredients by mass percentage: 0 to 99% kaolinite, 15 to 99% activated clay, 0 to 20% sepiolite, 0 to 45% diatomaceous earth, 0 to 80% mordenite, and 0 to 99% ZSM zeolite. The optimal result achieved is a reduction in sulfur content from approximately 1000 ppm to 27 ppm (removal of 97.3% of S). No mention is made of reducing nitrogen content.

[0009] Therefore, there is a need for a method to recover crude phenol from coal tar and remove nitrogen and sulfur contaminants from the crude phenol, which enables the crude phenol to be efficiently upgraded. Brief description of the attached diagram

[0011] Figure 1 The illustration shows one embodiment of the method of the present invention.

[0012] Figure 2 This is the GC-NCD chromatogram of sample 1 before adsorption.

[0013] Figure 3A This is the GC-NCD chromatogram of sample 1 after adsorption with bentonite-HCl.

[0014] Figure 3B This is the GC-NCD chromatogram of sample 1 after adsorption using HZSM-5 zeolite.

[0015] Figure 4A This is the GC-NCD chromatogram of sample 1 after adsorption with sepiolite.

[0016] Figure 4B This is the GC-NCD chromatogram of sample 1 after adsorption using HZSM-5.

[0017] Figure 5A This is the GC-NCD chromatogram of sample 1 after adsorption with sepiolite.

[0018] Figure 5B This is the GC-NCD chromatogram of sample 1 after adsorption with bentonite-HCl.

[0019] Figure 6A This is the GC-NCD chromatogram of sample 1 after adsorption with bleaching clay.

[0020] Figure 6B This is the GC-NCD chromatogram of sample 1 after adsorption with bentonite-HCl.

[0021] Invention Description

[0022] This method provides a way to remove contaminants from coal-derived phenols. Nitrogen compounds are much less reactive than oxygen and sulfur compounds, and they are strongly adsorbed onto the active sites of catalysts, which hinders the modification of crude phenols.

[0023] It has been found that a combination of extraction and subsequent adsorption methods can produce cleaner crude phenols from coal-derived feed streams with sulfur and nitrogen contents of less than 100 ppmw and, in some cases, less than 10 ppmw.

[0024] Coal-derived feed streams, such as low-temperature coal tar, medium-temperature coal tar, high-temperature coal tar, toluene-based acids, or crude phenol mixtures, contain phenol, alkylphenols (methylphenol (cresol), ethylphenol, dimethylphenol (xylenol), propoxyphenol, butylphenol, methylethylphenol, etc.), and heavier alkylphenols (such as indanol and naphthol). Coal tar is derived from coal dry distillation and gasification processes and is classified based on the temperature used for these processes (400–600 °C (low temperature), 600–1000 °C (medium temperature), and above 1000 °C (high temperature)). Toluene-based acids are a general term referring to combinations of phenols and alkylphenols, and can be obtained, for example, from coal or petroleum processing. Crude phenol mixtures can be obtained through coal tar processing and purification of phenol-containing waste from, for example, coking ovens, low-temperature carbonization, and hydrogenation units. The composition of the feed stream will vary depending on its source.

[0025] The coal-derived feed stream can be separated into various streams. Suitable separation methods include, but are not limited to, distillation, acid / base extraction, and solvent extraction. The crude phenol stream may contain a portion of the coal-derived feed stream. The crude phenol stream may contain one or more of the following: low-temperature coal tar stream, medium-temperature coal tar stream, high-temperature coal tar stream, toluene-based acid stream, or a mixture of crude phenols. The crude phenol stream may have a boiling point of approximately 300°C or lower. For example, the crude phenol stream may contain a portion of, for example, a low-temperature or medium-temperature coal tar distillate stream having a boiling point of approximately 300°C or lower.

[0026] Extraction methods are applied to crude phenol streams to produce an extract effluent stream with minimal impurities (organic nitrogen, organic sulfur, and neutral oil) to facilitate subsequent adsorption methods. Liquid-liquid extraction can be used to efficiently separate phenolic compounds from coal tar distillates (e.g., at approximately 300°C or lower). Suitable liquid-liquid extraction methods include, but are not limited to, acid-base liquid extraction and aqueous methanol liquid extraction. Acid / base liquid extraction has been found to be more effective for the removal of nitrogen and sulfur contaminants, although aqueous methanol extraction is safer and easier to operate. Other liquids can be used in the extraction, including but not limited to ethanol, propanol, glycols, and alkanolamines. For the removal of nitrogen and / or sulfur contaminants, these two extraction methods are superior to hydrogenation treatment because they do not destroy phenols.

[0027] In some embodiments, acid-base extraction reduces organic nitrogen in the coal tar distillate stream to below 100 ppmw and organic sulfur to below 100 ppmw or 50 ppmw. The coal tar distillate stream or a solution thereof in an aromatic solvent (e.g., toluene, benzene, xylene) is extracted multiple times with an alkaline aqueous solution (e.g., 3M sodium hydroxide solution). The combined extract solutions are then washed with an 80:20 mixture of hexane and dichloromethane to remove residual neutral and alkaline coal tar components. After acidification with an acidic solution (e.g., hydrochloric acid, sulfuric acid), crude phenols are collected as an oil, or extracted multiple times with dichloromethane to improve phenol recovery. The solvent is removed to obtain crude phenols in oil form.

[0028] An adsorption process is performed after the extraction method to remove residual trace amounts of refractory nitrogen and sulfur contaminants to obtain the low concentrations required for further processing of the stream. It has been found that improved adsorption can be achieved by using more than one adsorption zone. There can be at least two distinct adsorption zones. The first adsorption zone contains clay, and the second adsorption zone contains zeolite. The order of the adsorption zones is interchangeable.

[0029] The adsorption method can be carried out on a vibrator or column at temperatures ranging from room temperature to approximately 90°C, at atmospheric or super-atmospheric pressure for several hours to several days.

[0030] The first adsorption zone contains about 20% or more, or about 30% or more, or about 40% or more, or about 50% or more, or about 60% or more, or about 70% or more, or about 80% or more, or about 90% or more, or about 95% or more of one or more clays. Suitable clays include, but are not limited to, bentonite, HCl-activated bentonite, silica gel, sepiolite, and bleaching clay.

[0031] The second adsorption zone contains about 20% or more, or about 30% or more, or about 40% or more, or about 50% or more, or about 60% or more, or about 70% or more, or about 80% or more, or about 90% or more, or about 95% or more of one or more zeolites. Suitable zeolites include, but are not limited to, HZSM-5 zeolite and HBETA zeolite.

[0032] A third (or more) adsorption zone may exist, comprising a third adsorbent. The third adsorbent may comprise one or more clays and / or one or more zeolites. The third adsorption zone may comprise an adsorbent different from the first and / or second adsorbents. Alternatively, the third adsorbent may be the same as the first or second adsorbent. For example, in one embodiment, the clay of the first adsorbent may comprise one or more of bentonite and HCl-activated bentonite; the zeolite of the second adsorbent may comprise one or more of HZSM-5 zeolite and HBETA zeolite; and the third adsorbent may comprise one or more of HZSM-5 zeolite, HBETA zeolite, silica gel, sepiolite, and bleaching clay. In one example, the clay of the first adsorbent comprises HCl-activated bentonite, the zeolite of the second adsorbent comprises HZSM-5 zeolite, and the third adsorbent comprises one or more of bleaching clay or sepiolite.

[0033] The names of the first and second (and third or more) adsorbents are merely for distinction. It is not intended to specify which is the first in this method. In other words, the first adsorbent may be upstream of the second adsorbent, or downstream of it. The third adsorbent may be upstream of the first and second adsorbents, downstream of both, or between them (in all cases, the first adsorbent may be upstream or downstream of the second adsorbent).

[0034] The first and second adsorption zones may be located in a single container, or they may be located in different containers. When the first and second adsorption zones are located in the same container, the first adsorption zone may be located above the second adsorption zone, or the second adsorption zone may be located above the first adsorption zone.

[0035] Alternatively, when the first and second adsorption zones are located in the same container, if a third adsorption zone exists, it may be located in the same container as the first and / or second adsorption zones, or in a separate container.

[0036] Alternatively, there may be an adsorption zone containing a mixture of two or more adsorbents, wherein the adsorbents include one of clay and zeolite.

[0037] The first adsorption zone and / or the second adsorption zone may include at least one of a fixed bed, a fluidized bed, a moving bed, and a rotating bed.

[0038] The crude phenol stream can pass through the adsorbent bed in either an upward or downward flow direction.

[0039] The extract effluent stream may contain less than 200 ppmw, or less than 175 ppmw, or less than 150 ppmw, or less than 125 ppmw, or less than 100 ppmw, or less than 75 ppmw, or less than 50 ppmw. The extract effluent stream may contain less than 1500 ppmw, or less than 1250 ppmw, or less than 1000 ppmw, or less than 750 ppmw, or less than 500 ppmw, or less than 250 ppmw, or less than 100 ppmw. Organic sulfur content is measured using an Elementar trace SNcube N and S analyzer (available from Elementar Analysensysteme GmbH, Langenselbold, Germany) according to ASTM D5453-16 for sulfur analysis. Organic nitrogen content is measured using an Elementar trace SN cube N and S analyzer according to ASTM D4629-17 for nitrogen analysis.

[0040] The adsorbed effluent stream may contain less than 100 ppmw, or less than 75 ppmw, or less than 50 ppmw, or less than 40 ppmw, or less than 30 ppmw, or less than 25 ppmw, or less than 20 ppmw, or less than 15 ppmw, or less than 10 ppmw of organic sulfur compounds. The adsorbed effluent stream may contain less than 100 ppmw, or less than 75 ppmw, or less than 50 ppmw, or less than 40 ppmw, or less than 30 ppmw, or less than 25 ppmw, or less than 20 ppmw, or less than 15 ppmw, or less than 10 ppmw of organic nitrogen compounds. The presence of color in the crude phenol stream is an indication of nitrogen and / or sulfur contamination in the crude phenol, as phenolic compounds are colorless. Visually, the adsorbed effluent stream may be colorless, indicating a reduction in the content of organic nitrogen and / or organic sulfur compounds.

[0041] In one adsorption method, the first adsorbent is HCl-activated bentonite, the second is H-ZSM5, and the third is bleaching clay (after extraction), resulting in a colorless adsorbent effluent stream. Conversely, the same three adsorbents in a single mixed bed did not completely eliminate color from the adsorbent effluent stream. However, downstream methods may offer acceptable levels of nitrogen and sulfur contaminants.

[0042] This method can provide phenol recovery rates of 75% or greater, or 80% or greater, or 85% or greater, or 90% or greater, or 92% or greater, or 93% or greater, or 94% or greater, or 95% or greater. This can be compared with hydrogenation methods in which more than 90% of the phenols are destroyed.

[0043] The phenol recovery rate is calculated using the following formula:

[0044]

[0045] For example, no significant compositional changes were observed after using the 3-zone adsorption method with bentonite-HCl / H-ZSM5 / bleaching clay. The changes in phenolic composition before and after the adsorption method were determined by GC-MS analysis.

[0046] Figure 1 The illustration depicts method 100. A coal tar or crude phenol feed stream 105 is separated into one or more streams in one or more distillation columns 110. For example, the coal tar or crude phenol feed stream 105 may be separated into a stream 115 with a boiling point less than about 150°C, a crude phenol stream 120 with a boiling point from about 150°C to about 300°C, and a stream 125 with a boiling point greater than 300°C. Those skilled in the art will recognize that other fractions within the coal tar or crude phenol feed stream 105 are possible.

[0047] Crude phenol stream 120 contains most of the phenolic compounds from coal tar or crude phenol feed stream 105. It is fed to one or more extraction towers 130. A portion of the organosulfur and organonitrogen compounds are removed from crude phenol stream 120 to obtain an extract effluent stream 135 with reduced organosulfur and organonitrogen compound content compared to the incoming crude phenol stream 120, and an oil stream 140 containing reduced phenolic content and the organosulfur and organonitrogen compounds removed from crude phenol stream 120. The extraction method can be acid-base liquid extraction or aqueous methanol liquid extraction.

[0048] The extract effluent stream 135 is fed to an adsorption unit 145, which includes first and second adsorption zones containing first and second adsorbents. As is known in the art, the adsorption unit 145 may include one or more adsorption containers, each containing one or more adsorption zones. The adsorption unit may include three or more adsorption zones as described above. Additional portions of organosulfur and organonitrogen compounds are removed from the extract effluent stream 135 in the adsorption unit 145 to obtain an adsorbed effluent stream 150 with a reduced content of organosulfur and organonitrogen compounds compared to the incoming extract effluent stream 135.

[0049] The adsorbed effluent stream 150 can be sent downstream for phenol separation and / or further processing.

[0050] The selection of the adsorbent combination was based on findings from adsorbent selectivity studies of coal tar. Adsorption was measured using gas chromatography-nitrogen chemiluminescence detector (GC-NCD). NCD is a nitrogen-specific detection tool that is highly sensitive and can be used to detect residual nitrogen contaminants in coal tar samples because only nitrogen-containing compounds appear in the chromatogram.

[0051] It was found that a single adsorbent was insufficient to efficiently reduce contaminants to the desired levels. However, comparisons of the resulting GC-NCD chromatograms when the extract effluents were subjected in parallel to different single adsorbents under the same experimental conditions provided valuable information about the nitrogen adsorption selectivity of these adsorbents.

[0052] For example, Figure 2 The image shows the GC-NCD chromatogram of sample 1 before adsorption. Sample 1 is the effluent from acid-base extraction.

[0053] Figure 3A and 3B The use of bentonite-HCl (and) is shown separately. Figure 5B and 6B The same material, but different in scale) and HZSM-5 zeolite (with Figure 4B The GC-NCD chromatogram of sample 1 (using the same material but at different scales) after adsorption shows that the remaining peaks are different, which means that the two adsorbents adsorb different nitrogen molecules.

[0054] Figure 4A and 4B Showing the use of sepiolite (and) Figure 5A The same materials, same scale) and HZSM-5 zeolite (with Figure 3B The GC-NCD chromatogram of sample 1 after adsorption (using the same material but at different scales). The remaining peaks differ for both adsorbents, indicating that they adsorb different nitrogen molecules.

[0055] Figure 5A and 5B Showing the use of sepiolite (and) Figure 4A The same materials (same scale) and bentonite-HCl (with) Figure 3A and 6B The GC-NCD chromatogram of sample 1 (using the same material but at different scales) after adsorption. The difference in the remaining peaks indicates that they adsorbed different nitrogen molecules.

[0056] Figure 6A and 6B The use of bleaching clay and bentonite-HCl (with) are shown respectively. Figure 3A and 5B The GC-NCD chromatogram of sample 1 (using the same material but at different scales) after adsorption. The difference in the remaining peaks indicates that they adsorbed different nitrogen molecules.

[0057] Experiments using the effluent from aqueous methanol extraction yielded similar results, indicating that different adsorbents adsorbed different nitrogen molecules.

[0058] Adsorbent selectivity studies have demonstrated that different adsorbents adsorb different nitrogen compounds from the extract effluent. This indicates that the properties of adsorbents are complementary in terms of nitrogen pollutant removal, and that when used in combination, they produce a synergistic effect.

[0059] Therefore, it can be expected that different adsorbents adsorb different sulfur molecules.

[0060] Although the method for coal tar is described below for convenience, those skilled in the art will recognize that it can also be used for other coal-derived liquids, including but not limited to liquids produced by coal liquefaction methods. Example

[0061] Example 1 - Extraction Method

[0062] A portion of the coal tar distillate (150-250 °C, initial N content 4200 ppmw and S content 700 ppmw) was subjected to acid / base extraction. The distillate (2.3 kg) was dissolved in 5.6 kg of toluene. The resulting toluene solution was extracted three times at room temperature with 3.0 M NaOH aqueous solution (8.6 kg for the first extraction, 6.3 kg for the second, and 4.0 kg for the third). The combined aqueous phases were extracted twice with hexane / dichloromethane (4:1 v / v) (2.6 kg each time) to remove residual neutral and basic components. 6 M hydrochloric acid (9.5 kg) was slowly added to the aqueous phase at 10 °C with stirring to acidify to pH 1.0. The acidified aqueous phase was extracted three times with dichloromethane (5.3 kg each time). The combined dichloromethane solution was washed twice with distilled water (DI) (0.5 L each time) to remove residual salts. Dichloromethane and residual water were removed by rotary evaporation to obtain a crude phenol stream (1.25 kg, yield 55% by weight).

[0063] The effluent from the acid / base extraction method contained 96 ppmw nitrogen and 47 ppmw sulfur (Sample 1).

[0064] Another portion of the same distillate was subjected to an aqueous methanol extraction method. The distillate (1.0 kg) was dissolved in 4.0 L of methanol, followed by the addition of 1.7 L of DI water. The volume ratio of methanol to water was 70:30. A turbid mixture was produced as the less polar components (non-phenolic compounds) became insoluble. The turbid mixture in the aqueous methanol was extracted three times with hexane (1.0 L each time). Methanol and water were removed by rotary evaporation to obtain crude phenol oil, which was further extracted twice with 1.0 M hydrochloric acid (200 mL each time) to remove basic organic nitrogen compounds. Residual water was removed by rotary evaporation at 50 °C under vacuum (10 mmHg) for 4 hours, yielding a crude phenol stream (0.56 kg, 52 wt%).

[0065] The effluent from the aqueous methanol extraction method had 1468 ppmw nitrogen and 174 ppmw sulfur (sample 2).

[0066] Example 2 - Adsorption Method

[0067] Then, various adsorbents were used to adsorb samples 1 and 2.

[0068] Pretreatment of adsorbent:

[0069] Acid-activated bentonite (bentonite-HCl):

[0070] Add 80 mL of 3.0 M hydrochloric acid (HCl) to 40.0 g of bentonite. Heat the resulting mixture at 70 °C for 12 hours with gentle stirring. After filtration, dry the collected solid at 105 °C for 12 hours. Crush the dried HCl-treated bentonite and sieve it to 30-50 mesh before use. Store the dried bentonite under nitrogen atmosphere.

[0071] Zeolite adsorbents (HZSM-5, HBETA, etc.) were sieved (30-50 mesh) and calcined at 540℃ for 3 hours. All other adsorbents were pretreated at 150℃ for 1 hour before use to remove adsorbed compounds.

[0072] Adsorption Method 1 Sample 1 (10.0 g) was dissolved in 30.0 g of toluene, and then 5.0 g of bentonite-HCl was added. The resulting mixture was shaken for 2–24 hours. After filtration to remove the first adsorbent, 5.0 g of the second adsorbent HZSM-5 (Zeolvst, CBV3024E) was added. The resulting mixture was shaken for 2–24 hours. After filtration to remove the second adsorbent, 5.0 g of the third adsorbent sepiolite was added. The resulting mixture was shaken for 2–24 hours. After filtration to remove the third adsorbent and the solvent, a colorless oil with N and S contents of 5 ppmw and 6 ppmw, respectively, was obtained.

[0073] Adsorption Method 2 Sample 1 (10.0 g) was dissolved in 30.0 g of toluene, and then 5.0 g of bentonite-HCl was added. The resulting mixture was shaken for 2–24 hours. After filtration to remove the first adsorbent, 5.0 g of the second adsorbent HZSM-5 (Zeolyst, CBV3024E) was added. The resulting mixture was shaken for 2–24 hours. After filtration to remove the second adsorbent, 5.0 g of the third adsorbent bleaching earth was added. The resulting mixture was shaken for 2–24 hours. After filtration to remove the third adsorbent and the solvent, a colorless oil with N and S contents of 8 ppmw and 6 ppmw, respectively, was obtained. The phenol recovery rate was 93%.

[0074] Adsorption method 3Sample 1 (10.0 g) was dissolved in 30.0 g of toluene, and then a mixture of bentonite-HCl, HZSM-5 (Zeolyst, CBV3024E), and bleaching clay (5 g each) was added. The resulting mixture was shaken for 2–24 hours. After filtration to remove the adsorbent mixture and solvent, a light brown oil with N and S contents of 42 ppmw and 10 ppmw, respectively, was obtained. The phenol recovery rate was 92%.

[0075] Adsorption method 4 Sample 1 (10.0 g) was dissolved in 30.0 g of toluene, and then 5.0 g of bentonite-HCl was added. The resulting mixture was shaken for 2–24 hours. After filtration to remove the first adsorbent, 5.0 g of the second adsorbent HZSM-5 (Zeolyst, CBV3024E) was added. The resulting mixture was shaken for 2–24 hours. After filtration to remove the second adsorbent, 5.0 g of the third adsorbent HBETA (Clariant, HCZB150) was added. The resulting mixture was shaken for 2–24 hours. After filtration to remove the third adsorbent and the solvent, a pale yellow oil with N and S contents of 18 ppmw and 9 ppmw, respectively, was obtained.

[0076] Adsorption method 5 Sample 1 (10.0 g) was dissolved in 30.0 g of toluene, and then 5.0 g of bentonite-HCl was added. The resulting mixture was shaken for 2–24 hours. After filtration to remove the first adsorbent, 5.0 g of the second adsorbent HZSM-5 (Zeolyst, CBV3024E) was added. The resulting mixture was shaken for 2–24 hours. After filtration to remove the second adsorbent and the solvent, a light brown oil with N and S contents of 29 ppmw and 15 ppmw, respectively, was obtained. The phenol recovery rate was 95%.

[0077] Adsorption Method 6 Sample 1 (10.0 g) was dissolved in 30.0 g of toluene, and then 5.0 g of bentonite was added. The resulting mixture was shaken for 2–24 hours. After filtration to remove the first adsorbent, 5.0 g of the second adsorbent HZSM-5 (Zeolyst, CBV3024E) was added. The resulting mixture was shaken for 2–24 hours. After filtration to remove the second adsorbent and the solvent, a light brown oil with N and S contents of 62 ppmw and 22 ppmw, respectively, was obtained.

[0078] Adsorption Method 7Sample 1 (10.0 g) was dissolved in 30.0 g of toluene, and then 5.0 g of bentonite was added. The resulting mixture was shaken for 2–24 hours. After filtration to remove the first adsorbent, 5.0 g of the second adsorbent HZSM-5 (Zeolyst, CBV3024E) was added. The resulting mixture was shaken for 2–24 hours. After filtration to remove the second adsorbent, 5.0 g of the third adsorbent silica gel was added. The resulting mixture was shaken for 2–24 hours. After filtration to remove the third adsorbent and the solvent, a light brown oil with N and S contents of 42 ppmw and 12 ppmw, respectively, was obtained.

[0079] Adsorption method 8 Sample 1 (10.0 g) was dissolved in 30.0 g toluene, and then 5.0 g bentonite was added. The resulting mixture was shaken for 2–24 hours. After filtration to remove the first adsorbent, 5.0 g of the second adsorbent HZSM-5 (Zeolyst, CBV3024E) was added. The resulting mixture was shaken for 2–24 hours. After filtration to remove the second adsorbent, 5.0 g of the third adsorbent silica gel was added. The resulting mixture was shaken for 2–24 hours. After filtration to remove the third adsorbent, 5.0 g of the fourth adsorbent bleaching earth was added. The resulting mixture was shaken for 2–24 hours. After filtration and solvent removal, a colorless oil with N and S contents of 15 ppmw and 4 ppmw, respectively, was obtained. The phenol recovery rate was 93%.

[0080] Adsorption Method 9 Sample 1 (10.0 g) was dissolved in 30.0 g of toluene, and then 5.0 g of bentonite was added. The resulting mixture was shaken for 2–24 hours. After filtration to remove the first adsorbent, 5.0 g of the second adsorbent HZSM-5 (Zeolyst, CBV3024E) was added. The resulting mixture was shaken for 2–24 hours. After filtration to remove the second adsorbent, 5.0 g of the third adsorbent HBETA (Clariant, HCZB150) was added. The resulting mixture was shaken for 2–24 hours. After filtration to remove the third adsorbent and the solvent, a light brown oil with N and S contents of 26 ppmw and 9 ppmw, respectively, was obtained.

[0081] Adsorption method 10Sample 1 (10.0 g) was dissolved in 30.0 g of toluene, and then 5.0 g of bentonite was added. The resulting mixture was shaken for 2–24 hours. After filtration to remove the first adsorbent, 5.0 g of the second adsorbent HZSM-5 (Zeolyst, CBV3024E) was added. The resulting mixture was shaken for 2–24 hours. After filtration to remove the second adsorbent, 5.0 g of the third adsorbent HBETA (Clariant, HCZB150) was added. The resulting mixture was shaken for 2–24 hours. After filtration to remove the third adsorbent, 5.0 g of the fourth adsorbent, bleaching earth, was added. The resulting mixture was shaken for 2–24 hours. After filtration and removal of the solvent, a colorless oil with N and S contents of 17 ppmw and 5 ppmw, respectively, was obtained.

[0082] Adsorption Method 11 Sample 2 (10.0 g) was dissolved in 30.0 g of toluene, and then 5.0 g of bentonite-HCl was added. The resulting mixture was shaken for 2–24 hours. After filtration to remove the first adsorbent, 5.0 g of the second adsorbent HZSM-5 (Zeolyst, CBV3024E) was added. The resulting mixture was shaken for 2–24 hours. After filtration to remove the second adsorbent, 5.0 g of the third adsorbent silica gel was added. The resulting mixture was shaken for 2–24 hours. After filtration to remove the third adsorbent and the solvent, a brown oil with N and S contents of 403 ppmw and 96 ppmw, respectively, was obtained.

[0083] Adsorption method 12 Sample 2 (10.0 g) was dissolved in 30.0 g of toluene, and then 5.0 g of bentonite-HCl was added. The resulting mixture was shaken for 2–24 hours. After filtration to remove the first adsorbent, 5.0 g of the second adsorbent HZSM-5 (Zeolyst, CBV3024E) was added. The resulting mixture was shaken for 2–24 hours. After filtration to remove the second adsorbent, 5.0 g of the third adsorbent silica gel was added. The resulting mixture was shaken for 2–24 hours. After filtration to remove the third adsorbent, 5.0 g of the fourth adsorbent HBETA (Clariant, HCZB150) was added. The resulting mixture was shaken for 2–24 hours. After filtration and solvent removal, a brown oil with N and S contents of 299 ppmw and 59 ppmw, respectively, was obtained.

[0084] Table 1

[0085] Adsorption feed from acid-base extraction (sample 1)

[0086] (N 96npmw, S 47ppmw)

[0087] Adsorption methods Effluent N ppmw Effluent S ppmw Phenolic recovery rate, % 1 5 6 2 8 6 93 3 42 10 92 4 18 9 5 29 1 5 95 6 62 22 7 42 12 8 15 4 93 9 26 9 10 17 5

[0088] Table 2

[0089] Adsorption feed from 70% aqueous methanol extraction (sample 2)

[0090] (N 1468ppmw, S 174ppmw)

[0091] Adsorption methods Effluent N ppmw Effluent S ppmw Phenolic recovery rate, % 11 403 96 12 299 59

[0092] Although acid / base extraction and 70% aqueous methanol extraction are comparable in their ability to extract phenols from coal tar, acid / base extraction is significantly more efficient at removing nitrogen and sulfur contaminants than aqueous methanol extraction.

[0093] The optimal adsorbent combinations for nitrogen and sulfur pollutant removal efficiency are bentonite-HCl / HZSM-5 / bleaching clay and bentonite-HCl / HZSM-5 / sepiolite. Both combinations reduce nitrogen and sulfur pollutant levels to below 10 ppm.

[0094] The term “approximately” means within 10%, 5%, or 1% of that value.

[0095] Although at least one exemplary embodiment has been given in the foregoing detailed description of the invention, it should be recognized that numerous variations exist. It should also be understood that the one or more exemplary embodiments are merely examples and are not intended to limit the scope, applicability, or configuration of the invention in any way. Rather, the foregoing detailed description provides convenient guidance to those skilled in the art for implementing exemplary embodiments of the invention. It is to be understood that various changes can be made to the function and arrangement of the elements described in the exemplary embodiments without departing from the scope of the invention as set forth in the appended claims.

Claims

1. A method for removing contaminants from coal-derived crude phenols, comprising: Extraction methods are used to remove organosulfur compounds and organonitrogen compounds from a crude phenol stream containing coal-derived crude phenols to form one or more extract effluent streams with reduced contents of organosulfur compounds and organonitrogen compounds compared to the crude phenol stream. and An adsorption method is used to remove one or more portions of organosulfur compounds and organonitrogen compounds from an extract effluent stream. The adsorption method includes a first adsorption zone having a first adsorbent and a second adsorption zone having a second adsorbent to form an adsorbed effluent stream having a reduced content of one or more organosulfur compounds and organonitrogen compounds compared to the extract effluent stream. The first adsorbent comprises clay, and the second adsorbent comprises zeolite.

2. The method according to claim 1, wherein the reduced organic sulfur compound content in the extraction effluent stream is less than 100 ppmw; or wherein the reduced organic nitrogen compound content in the extraction effluent stream is less than 100 ppmw; or both.

3. The method according to any one of claims 1-2, wherein the reduced organic sulfur compound content in the adsorbed effluent stream is less than 10 ppmw; or wherein the reduced organic nitrogen compound content in the adsorbed effluent stream is less than 10 ppmw; or both.

4. The method according to any one of claims 1-2, wherein the phenol recovery rate is 90% or greater.

5. The method according to any one of claims 1-2, wherein the extraction method comprises an acid-base liquid extraction method or an aqueous methanol liquid extraction method.

6. The method according to any one of claims 1-2, wherein the clay comprises one or more of bentonite and HCl-activated bentonite.

7. The method according to any one of claims 1-2, wherein the zeolite comprises one or more of HZSM-5 zeolite and HBETA zeolite.

8. The method according to any one of claims 1-2, wherein the adsorption method further comprises a third adsorption region containing a third adsorbent.

9. The method according to claim 8, wherein the third adsorbent is different from the first adsorbent and the second adsorbent.

10. The method according to claim 8, wherein the clay of the first adsorbent comprises one or more of bentonite and HCl-activated bentonite, wherein the zeolite of the second adsorbent comprises one or more of HZSM-5 zeolite and HBETA zeolite, and wherein the third adsorbent comprises one or more of HZSM-5 zeolite, HBETA zeolite, silica gel, sepiolite and bleaching clay.

11. The method according to any one of claims 1-2, wherein the adsorption method further comprises a third adsorption zone having a third adsorbent, and wherein the first adsorbent comprises HCl-activated bentonite, the second adsorbent comprises HZSM-5 zeolite, and the third adsorbent comprises one or more of bleaching clay or sepiolite.

12. The method according to any one of claims 1-2, wherein the first adsorption region and the second adsorption region are in separate containers.

13. The method according to any one of claims 1-2, wherein the first adsorption region and the second adsorption region are in a container, wherein the first adsorption region is located above the second adsorption region, or wherein the second adsorption region is located above the first adsorption region.

14. The method according to any one of claims 1-2, wherein the crude phenolic stream passes through the adsorbent bed in an upward or downward flow direction.

15. The method according to any one of claims 1-2, wherein the adsorbed effluent stream is colorless.

16. The method according to any one of claims 1-2, wherein the crude phenol stream comprises a portion of a coal-derived feed stream having a boiling point of 300°C or lower.

17. The method according to any one of claims 1-2, wherein the crude phenol stream comprises one or more of a low-temperature coal tar stream, a medium-temperature coal tar stream, a high-temperature coal tar stream, a toluene acid stream, or a mixture of crude phenols.

18. The method according to any one of claims 1-2, wherein at least one of the first adsorption zone and the second adsorption zone comprises at least one of a fixed bed, a fluidized bed, a moving bed, and a rotating bed.

19. A method for removing contaminants from coal-derived crude phenols, comprising: Extraction methods are used to remove organosulfur compounds and organonitrogen compounds from a crude phenol stream containing coal-derived crude phenols to form an extract effluent stream having a reduced content of one or more organosulfur compounds and organonitrogen compounds compared to the crude phenol stream; wherein the extraction method includes one or more of acid-base liquid extraction and aqueous methanol liquid extraction. and An adsorption method is used to remove one or more portions of organic sulfur compounds and organic nitrogen compounds from an extract effluent stream. The adsorption method includes a first adsorption zone having a first adsorbent and a second adsorption zone having a second adsorbent to form an adsorbed effluent stream having a reduced content of one or more organic sulfur compounds and organic nitrogen compounds compared to the extract effluent stream. The first adsorbent comprises one or more of bentonite, HCl-activated bentonite, silica gel, sepiolite, and bleaching clay, and the second adsorbent comprises HZSM-5 zeolite and HBETA zeolite.

20. A method for removing contaminants from coal-derived crude phenols, comprising: Extraction methods are used to remove organosulfur compounds and organonitrogen compounds from a crude phenol stream containing coal-derived crude phenols to form one or more extract effluent streams with reduced contents of organosulfur compounds and organonitrogen compounds compared to the crude phenol stream. and An adsorption method is used to remove one or more portions of organosulfur compounds and organonitrogen compounds from an extraction effluent stream. The adsorption method includes a first adsorption zone having a first adsorbent, a second adsorption zone having a second adsorbent, and an optional third adsorption zone having a third adsorbent to form an adsorbed effluent stream having a reduced content of one or more organosulfur compounds and organonitrogen compounds compared to the extraction effluent stream. The first adsorbent comprises one or more of bentonite, HCl-activated bentonite, silica gel, sepiolite, and bleaching clay. The second adsorbent comprises one or more of HZSM-5 zeolite and HBETA zeolite. The third adsorbent comprises one or more of bentonite, HCl-activated bentonite, silica gel, sepiolite, bleaching clay, HZSM-5 zeolite, and HBETA zeolite.

Images