Patent Application
20190233738
This Application claims priority to Mexican Patent Application No. MX/a/2018/001281, filed Jan. 30, 2018, the entire contents of which is incorporated herein by reference.
The present disclosure relates to a process for extracting fluoridated (HF) and organofluoridated (R—F) compounds, from alkylation or “alkylated” gasoline, which are undesirable contaminants in the final product. The alkylated product is obtained in the refineries by means of the catalytic process of alkylation of isoparaffins with olefins and for this a hydrofluoric acid (HF) catalyst is used, later the product is transferred to a fractionating tower to effect the separation of liquid products of high octane and gases that did not react or that contain fluorine in their composition, or that do not meet the product standards, which are recycled in the process. In some cases imbalances occur in the operation of the separation process, so that variable amounts of HF or R—F are introduced into the product, above the norm specified for gasolines, e.g., <3 ppm (HF). In some cases, these amounts can reach such high values that environmental and health risks are presented, as well as potential damage to the infrastructure and operational personnel. The mitigation of this problem is important to obtain an alkylated product free of fluoridated contaminants, by means of an extraction procedure at room temperature, the main subject of the present disclosure, which consists in effecting the extraction of fluoridated compounds by means of a liquid-liquid system, from the direct contact of an ionic liquid with the alkylated hydrocarbon. This procedure is scalable to the industrial process through the use of modular extraction columns, which can be installed at the exit of the fractionating plant of the process or through the modification to the distillation column of the process (fractionating plant).
The ionic liquids of the present disclosure are immiscible in hydrocarbons and have the property of extracting fluoridated compounds (HF: hydrogen fluoride, and R—F: organofluorides) that contaminate the high octane hydrocarbon product, through a liquid-liquid extraction process, at ambient pressure (1 atm) and at temperatures between 25 and 60° C.
Specifically, the present disclosure is directed to a process for removing organofluoridated compounds (RF) and hydrogen fluoride (HF) from alkylation gasoline by using chemical agents based on ionic liquids whose general formula is C+A−, where C+ represents an organic type cation, specifically alkylpyridinium, dialkylimidazolium or tetraalkylammonium; while the type A− anions are typically halides, i.e., salts of some transition metals, especially iron and aluminum and other anions of the organic type.
The process of alkylation of isoparaffins (i-C4) with olefins (C4=) is one of the most appreciated in refineries because it imparts high quality characteristics to the “pool” of gasolines, among them the octane number (RON=94.5), low vapor pressure (P<7 psi) and the absence of contaminants such as sulfur and nitrogen. The alkylation process uses liquid acid catalysts, for example HF (hydrogen fluoride) or H2SO4 (sulfuric acid), the former being a very strong acid that efficiently promotes the alkylation reaction at low temperatures (≤32° C.); in industrial practice the alkylation process that uses HF as a catalyst is carried out under strict control and safety conditions, but the evaporation of small fractions of the acid or imbalances in some units cause some traces of HF to pass to the alkylated product, exceeding the product standards and specifications (≤3 ppm). Fluoridated compounds include HF and organic fluorides (R—F), which are not desirable products in gasoline, for various reasons related to environmental pollution, health and corrosion damage to automotive parts. The organic fluorides that have been detected in some alkylation gasolines consist of 3 to 14 carbon atoms per molecule, for example the following have been identified: 2-fluoropropane, 2-fluorobutane, 2-fluoro-2-methylpropane, 2-fluoropentane, 2-fluoro-2-methylbutane, 2-fluoro-3-methylbutane, isomers of methylfluorobutane, 2-fluorohexane, 3-fluorohexane, methylfluoropentanes, dimethylfluorobutanes, fluoroheptans, fluoromethylhexanes, dimethylfluoropentanes, fluorooctans, fluoromethylheptans, dimethylfluorohexanes, fluorotrimethylpentanes fluorononanes, fluoromethyloctans, dimethylfluoroheptanes and fluorotrimethylhexanes.
In contrast, HF is a compound relatively soluble in hydrocarbons (approximately 1% by weight is retained in the hydrocarbon layer), so it is usually recovered by the use of a column packed with aluminum (metal) rings. In turn, this column serves as a catalyst for the decomposition of organofluoridated compounds (R—F). The HF released in the packed column is recovered and returned to the reactor, while the bottoms of the reactor can be treated in a tower packed with bauxite (AlO (OH)), in order to remove the remaining organic fluorides. This stage of the process is important because the dissolved organic fluorides have a high corrosivity, which is undesirable in the alkylated product and their presence decreases the octane number of the alkylated product, besides that they are very toxic even at low concentrations. Therefore, the need arises to have a means of control of HF to avoid or reduce it below the norm (<3 ppm HF) in alkylation gasolines, therefore the technology described in the present disclosure meets this need by means of a liquid-liquid extraction process that efficiently reduces the amount of fluoridated compounds (HF and R—F) in the alkylation gasoline.
In addition, the exhaustive removal of fluoridated compounds prevents corrosion by HF of installations such as pipelines, storage tanks and industrial plants, especially those used in the process of isoparaffin alkylation (i-C4).) with olefins (C4=), which use hydrogen fluoride (HF) as a catalyst, thus reducing the problems of environmental pollution, the deterioration of facilities and the risk associated with the presence of fluoridated compounds in the product, both in the industrial facilities and in the gas tank of the final user of this chain.
On the other hand, ionic liquids have attracted a lot of attention because their properties include almost no vapor pressure, they are not flammable, they are not corrosive and have a low toxicity, resulting in excellent substitutes for the volatile organic solvents which are the most commonly used in industry (Wasserscheid, P.; Keim, W. (Eds.); these characteristics have promoted rapid development and deployment of their industrial applications (Rogers, R D; Seddon, K. R (Eds.) Ionic Liquids: Industrial Applications of Green Chemistry, ACS, Boston, 2002.). Ionic liquids have been proposed as a novel alternative for different industrial applications and these chemical agents have shown that they have an interesting potential for use as “green solvents” and as catalysts in the polymerization, alkylation and Diels-Alder reactions, among others, as well as in electrochemical and separation processes. In addition, the use of ionic liquids as solvents in the process of CO2 extraction, aromatic and sulfur compounds in hydrocarbon mixtures, represent an important potential for their application as a whole.
On the other hand, control by removing fluorine from aqueous effluents is a practice that avoids fluorosis [Luo Fang, Kedar Nath Ghimire, Masayuki Kuriyama, Katsutoshi Inoue and Kenjiro Makino. J Chem Technol Biotechnol 78: 1038-1047 (2003)], which is carried out by precipitation of the fluoride ion with calcium salts, thus generating a precipitate of insoluble CaF2 in the pH range between 4 and 10.4; also, the aluminum salts Al(OH)3 [Rongshu W, Haiming L, Ping N and Ying W, Study of a new adsorbent for fluoride removal from waters. Water Qual Rea J Canada 30: 81-88 (1995)] have been used, as well as activated carbon, alumina and bone ash [Killedar D J and Bhargava D S, Effects of stirring rate and temperature on fluoride removal by fishbone charcoal. Ind J Environ Health 35: 81-87 (1993), Haron M J, Wan Yunus W M Z and Wasay S A, Sorption of fluoride ions from aqueous solutions by a yttrium-loaded poly (hydroxamic acid) resin. Int J Environ Studies 48: 245-255 (1995); Qureshi S Z, Khan M A and Rahman N, Removal of fluoride ions by zirconium (IV) arsenate vanadate using ion-selective electrode. Water Treat 10: 307-312 (1995), Srimurali M, Pragathi A and Karthikeyan J, A study on removal of fluorides from drinking water by adsorption onto low-cost materials. Environmental Pollution 99: 285-289 (1998)]. Also, ion exchange resins and other materials have been used [Cengeloglu Y, Esengul K and Ersoz M, Removal of fluoride from aqueous solution by using red mud. Sep Sci Technol 28: 81-86 (2002) Yokabayashi Y, Oh R, Nakagawa T, Tanaka H and Chikuma M, Selective collection of fluoride ion on anion exchange resin loaded with Alizarin Fluorine Blue Sulfonate. Analyst 113: 829-832 (1998)].
Some adsorbent materials are effective in reducing the fluorine content in water, but in these cases the fluoride concentration remains above the permitted levels (>5 ppm), so research is still going on for looking at the most effective systems that could reduce the fluorine content to permitted levels (1-1.5 mg/L). In contrast, the scientific and patent literature shows very few references about the removal of fluoridated species in the organic environment. For example, some patents [Randolph B. B., Hoover K. C., U.S. Pat. No. 6,878,350 (2002), Randolph B. B., Hoover K. C., U.S. Pat. No. 6,114,593 (2000)] present a process for reducing one of the organofluoridated compounds present in alkylation gasoline by using catalytic materials.
However, the present disclosure relates to the use of ionic liquids in the removal of fluoridated compounds present in the alkylation gasoline.
The present disclosure is related to the application of ionic liquids with effective properties to remove contaminating fluoridated compounds that are found in the organic phase, in particular those present in gasolines obtained by the process of alkylation of isobutanes with butenes. The disclosure relates to a process for effecting the removal of fluoridated compounds by liquid-liquid extraction (ionic liquid-fluoridated species), which is based on a greater chemical affinity of the fluoridated compounds for the medium containing the ionic liquid, with respect to the hydrocarbon continuous medium in which they are dissolved, without detriment of the hydrocarbon continuous medium. The extraction with vigorous agitation of the two phases, followed by a separation process, causes the transfer of the phase formed by the ionic liquid and, as a result, the total fluorine content is considerably reduced in the hydrocarbon phase, thus releasing the latter of the contaminants that affect its specification as a product.
The ionic liquids used in this disclosure have the general formula C+A−, where C+ represents an organic cation, specifically of the following types: alkyl pyridinium, dialkyl imidazolium and tetraalkylammonium; while the anion A− may be of the inorganic type, for example, but not exclusively, halides, nitrates, phosphates, sulfates, salts of some transition metals especially iron and aluminum and other anions of the organic type, such as, for example, but not exclusively, triflates, acetates, benzoates, trifluoroacetate, hexafluorophosphate and tetrafluoroborate.
The present disclosure uses the synthesis of ionic liquids by two methods. The first is based on the synthesis by a Radziszewski type reaction, from which primary amines, aldehydes and a mineral or organic acid react exothermically in a single step, producing an ionic liquid by condensation [Arduengo III et al., U.S. Pat. No. 5,077,414 (1991), Arduengo III et al., U.S. Pat. No. 6,177,575 B1 (2001)]. The second method consists of two stages, the first stage is based on using the alkylation process of amines by a heating process, both conventional and unconventional, for example through the use of a microwave or ultrasound source, which offer significant advantages as are the elimination of conventional solvents during the alkylation stage, as well as in the purification, hence obtaining products of greater purity and with a more rapid formation, hence increasing the yield of the reactions; it is possible to synthesize stoichiometric quantities, avoiding the excessive use of reagents and decreasing the reaction time, as well as the cost of manufacturing and, subsequently, the second stage consists of exchanging anions, which is obtained by means of a metathesis reaction of the halogenated anion or through the exchange of ion with salts or acids that contain the desired anion.
In addition, the amounts of the ionic liquid are optimixed, in relation to the amount of hydrocarbon to be treated, thus obtaining outstanding results in the removal of fluoridated compounds with 1:10 ratios of ionic liquid to hydrocarbon, hence being able to reach optimal relations from 1:20 to 1:50, in a temperature range between 25 and 45° C.
The evaluation of the performance of ionic liquids (LIs) to remove fluoridated compounds from alkylation gasoline was evaluated through the liquid-liquid extraction process, using separation funnels made of the highest quality laboratory grade polypropylene copolymer (PPCO), with a capacity of 250 mL and by extraction with vigorous stirring of the ionic liquid and gasoline, in a 1:10 ratio (1 g of LI: 10 g grams of alkylate) at room temperature and 15 minutes extraction, with a stirring speed of 900 rpm and with a phase separation time of 60 minutes. Subsequently, the gasoline and the ionic liquid are separated by decanting, quantitatively determining the amount of HF, using the method 8007-AK Philips Petroleum Co.
Table 1 shows the removal percentages obtained from alkylation gasoline contaminated with fluoridated compounds, e.g., >150 ppm (HF).
Some additional benefits in accordance with this disclosure are the optimization of the amounts used in the process of removal of fluoridated compounds, on the use of the ionic liquid in relation to the amount of hydrocarbon, thus obtaining optimum results with 1:10 ratios of ionic liquid to hydrocarbon, thus being able to reach ratios of 1:20 and up to 1:50.
Once the extraction time and the molar ratio of alkylate/ionic liquid to obtain the highest extraction efficiency of HF were defined, the following extractions were made as illustrated in Tables 5 to 8, with the ionic liquids reported in Table No 0.1; the extraction time was 15 minutes, with a molar ratio of 1/100 Ionic Liquid/Alkylate, respectively; Tables No. 5, 6, 7, 8 show the results corresponding to the percentage of HF extracted, as well as the percentage of extraction after the ionic liquid was regenerated.
A mixture of 1-methylimidazole (0.086 mol) and 1-bromobutane (0.086 mol) was placed in a ball flask with approximately 30 ml of toluene, the flask was fitted with a magnetic stirrer and a reflux system on an electric plate to maintain the temperature of the reaction at 60° C. for 48 hours until two phases are present. The upper phase contains the raw material that did not react, decanted, while the lower phase is the product, which was washed with approximately 60 ml of ethyl acetate. The ethyl acetate and the product are stirred vigorously and separated by means of a separating flask (60 ml×2). The residual ethyl acetate is removed by heating the product [BMI] [Br] in a rotary evaporator at 70° C. The pure product is a clear viscous yellow liquid. Performance 95.5%. IR (film): 2963.1575, 1152, 760, 613 cm−1. 1H NMR (300 MHz, D2O, ppm): 0.92 (t, J=7.4.3H), 1.31 (sx, 2H), 1.86 (q, 2H), 3.92 (s, 3H), 4.22 (t, 2H), 7.49 (dd, 2H), 8.8 (s, 3H). 13C NMR (75 MHz, D2O, ppm): 13.1, 19.2, 31.7, 36.2, 49.7, 122.7, 123.9, 136.2
The Ionic liquids are shown in Table 1, which are based on imidazole type rings with different substitutions on the amino groups and having in common the bromide counterion (Table inputs 1-5), were synthesized as indicated in example 1. As shown by Table 1, these liquids have the property for HF removal in the range between 60-70%, which is lower than ionic liquids shown in the following examples of this document.
For the synthesis of [BMI] [NTf2], 0.01 mol [BMI] [Br] was used, which was transferred to a beaker and dissolved with deionized water, an aqueous solution of 0.01 mol was added to the solution LiNTf2, and was left stirring for 3 hours. The purification process was followed, by decanting and washing the product with H2O, since the product is immiscible. The final product is colorless, obtaining a yield of 90%. IR (Film): 3161, 2970, 2878, 1578, 1352, 1196, 1052, 743, 617, 574. 1H NMR (300 MHz, D2O, ppm): 0.93 (t, 3H), 1.36 (sx, 2H), 1.90 (q, 2H), 4.04 (s, 3H), 4.34 (t, 2H), 7.73 (dd, 2H), 8.99 (s, 1H). 13C NMR (300 MHz, D 2 O, ppm): 12.8, 19.1, 31.9, 35.8, 49.5, 118.1, 122.6, 124.0, 136.6, 206.7
The list of ionic liquids based on the imidazole ring and type N(Tf)2 counterions follow the synthetic procedures as described above (Table No. 1, entry 23-27). This shows a series of ionic compounds that meet the defined characteristics but are not unique or exclusive to the ionic species mentioned in Table No. 1. These ionic liquids have outstanding properties, as illustrated in Table No. 2, although they are not unique or exclusive to the class of ionic liquids of the present disclosure. EMI.N(Tf)2 liquids have an HF extraction capacity of 86.8%, which decreases to 82.3% in the second extraction cycle, hence reaching 85.5% removal of HF after its regeneration by means of water washing.
The ionic liquids with general formula PMI.N(Tf)2 were synthesized similarly as shown in example 2, and are characterized by having a side chain formed by a propyl radical, with an extraction capacity as illustrated in Table No. 3, wherein it is observed the variation of the percentage of extraction of HF as a function of time, as well as its extraction capacity after regeneration by means of water washing.
The variation of the extraction capacity with the contact time (10, 15 and 30 minutes) is illustrated in Table No. 4, without limiting the type of extractants of the present disclosure, on the contrary, the ionic liquids EMI.N(Tf)2 and PMI.N(Tf)2 show increasing rates for removal of HF from the alkylated product, as a function of contact time, thus reaching 90% removal when the IL's side chains are shorter, i.e., EMI.N(Tf)2; the HF removal can reach up to 96.7% when the side chain is longer, i.e., PMI.N(Tf)2. The percentage of extraction increases with the contact time for both types of ionic liquids, thus reaching values of 90 and 96% removal after 30 minutes of contact time, respectively.
The synthesis of the ionic liquid [BMI]Cl, was carried out by adding 37% formaldehyde (1 mole) and hydrochloric acid (1 mole) in a 37% aqueous solution to a ball flask with constant agitation for 30 minutes at room temperature. Then, it is left to cool down using an ice bath until temperature is below 10° C., then butylamine (1 mol) and methylamine (1 mol) are added and when the addition is over, it is allowed to reach room temperature, hence it is kept stirring for 30 minutes more, then glyoxal is added slowly in 40% aqueous solution, thus leaving it 30 minutes more, with both mixtures at room temperature. Then, the temperature is increased to 35-40° C. for 5 hours. Hence, this is placed in the roto-evaporator at 70° C. at 50 mbar. In these conditions the yield is 96%. IR (film) 3311, 3123, 2910, 1658, 1561, 1159, 1067 cm-1; 1H NMR (300 MHz, DMSO-d6, ppm) 3.7-3.3 (m, 4H), 4.4 (m, 4H), 7.8 (d, 2H), 9.23 (s, 1H); 13C NMR (300 MHz) δ (ppm) 51.66, 58.0, 122.6, 136.6.
The ionic liquids synthesized by this procedure are shown in Table 1, entry 7-10, varying only the type of amine, in the same Table the percentage of hydrocarbon HF extraction is shown according to the general procedure described in the first section.
For the synthesis of [BMI]CF3SO3, 0.01 mol of [BMI][Cl] was synthesized according to example 4, then was transferred to a beaker and dissolved with deionized water, mixed with an aqueous solution 0.01 mol LiCF3SO3, hence was kept under stirring for 3 hours. The purification process is followed by washing with deionized H2O (20 ml×2). The product is colorless and not very viscous; the yield was 94%. IR (film): 161, 2970, 2878.1578, 1352, 1196, 1052, 743, 617, 574. 1H NMR (300 MHz, D2O, ppm): 0.93 (t, 3H), 1.36 (sx, 2H), 1.90 (q, 2H), 4.04 (s, 3H), 4.34 (t, 2H), 7.73 (dd, 2H), 8.99 (s, 1H). 13C NMR (300 MHz, D2O, ppm) 12.8, 19.1, 31.9, 35.8, 49.5, 118.1, 122.6, 124.0, 136.6, 206.7.
According to the data shown in Table 1 (entry 16) an ionic liquid with anion CF3SO3 presents an HF extraction capacity of 83%.
The ionic liquids that are not described in this section were synthesized according to example 4, using different types of amines and acids.
As shown in Table 1, the removal capacity of fluoridated compounds is between 50% and 99% extraction, as well as in Tables 2-8 it is shown that the extraction capacity of the fluoridated compounds with ionic liquids can be determined in a contact time range, as well as the number of extractions per batch of each extraction.
| Number | Date | Country | Kind |
|---|---|---|---|
| MX/A/2018/001281 | Jan 2018 | MX | national |
