RU2459861C2 - Neutraliser/absorbent for hydrogen sulphide and volatile mercaptans - Google Patents

Abstract

FIELD: chemistry.

SUBSTANCE: invention relates to a reactant - absorbent for hydrogen sulphide and volatile mercaptans in liquid fuel, which is a composition containing 1,3,5-tri-(-hydroxyethyl)-hexahydro-S-triazine (compound I), hydroxymethylurea (compound II) and 1,3-bis (hydroxymethyl)urea (compound III) in an organic solvent (compound IV) in concentration of 68-88, 1.5-4.5, 0.5-2.5, 10-25 wt%, respectively, whose structure is given below

(compound I)

(compound II)

(compound III) ROH, where R is C₁-C₄, HOCH₂CHROH, where R is H or C₁-C₂, ROCH₂CH₂OH, where R is C₁-C₄ (compound IV).

EFFECT: reagent, having high binding capacity with respect to active sulphur compounds, which does not contain free formalin and amines and, on the hazard class, relates to class 3 moderately hazardous substances.

10 ex, 1 tbl

Description

The invention relates to the field of oil refining and petrochemicals, and in particular to a converter / scavenger of hydrogen sulfide and volatile mercaptans in fuel oil and other petroleum products with a reduced level of toxicity.

Toughening environmental requirements for oil products is a modern trend in the global market. In accordance with the requirements of European standards, as well as the technical regulation "On requirements for automobile and aviation gasoline, diesel and marine fuel, jet fuel and heating oil", which came into force in Russia in 2008, fuel oil should not contain hydrogen sulfide and volatile mercaptans.

Hydrogen sulfide and volatile mercaptans are found in crude oil, and are formed during its direct distillation and in secondary refining processes as a result of thermal and thermocatalytic destruction of the initial sulfur-containing compounds, and are undesirable components in commercial fuel oil and other petroleum products. The content of hydrogen sulfide and mercaptans in the residues of secondary processes is significantly higher compared to straight-run fuel oil due to higher temperatures. In addition, the content of hydrogen sulfide and mercaptans in dark oil products naturally increases with the involvement of heavy and sour crude oils in processing.

Hydrogen sulfide contained in fuel oil, during storage, pumping and transportation, is concentrated in the gas phase of tanks and tanks, which can lead to the creation of explosive concentrations, as well as to exceed its maximum permissible concentration (MPC) in air.

Hydrogen sulfide is extremely toxic. Air containing 300 ppm hydrogen sulfide is already considered hazardous. LD ₅₀ (the concentration in which a substance present in air kills 50% of experimental mice or rats with an experiment duration of 1 or 4 hours) for hydrogen sulfide is 713 ppm. A typical concentration of hydrogen sulfide in air above a fuel oil, an untreated additive, in an airtight tank reaches 1000 ppm. In addition, hydrogen sulfide and mercaptans have a strong unpleasant odor.

The use of reagents - neutralizers / absorbers allows you to chemically bind toxic and corrosive sulfur compounds - hydrogen sulfide and mercaptans present in the fuel, preventing them from entering the atmosphere. Due to this, the use of the reagent makes it possible to minimize the content of free hydrogen sulfide in fuel oil to meet the requirements of European standards, which is especially important when exporting fuel oil. It should be noted that the reagents do not remove sulfur compounds from the fuel, but bind them (convert sulfur compounds from the active form to inactive), while neutralizing the smell.

The working concentration of additives depends on the concentration of hydrogen sulfide in fuels and is usually 5-20 ppm per 1 ppm concentration of H ₂ S in a liquid state.

As additives, mainly used are compounds from the group of organic bases, usually ethanolamines, as well as formalin and the products of the interaction of formalin with various amines, alcohols or urea.

Known neutralizer of hydrogen sulfide and light mercaptans (patent RU 2302523), which includes formalin 30-58 wt. %, alkali metal hydroxide or carbonate, mainly sodium 0.1-3%, hexamethylenetetramine 15-25% and tertiary amino alcohol, preferably triethanolamine and / or methyldiethanolamine, the rest. Another variant of a catalyst is described that additionally contains a bactericidal preparation, preferably of the brand “Bacid” or “Soncid”.

A known method of reducing the level of hydrogen sulfide in a liquid or gas by treating a liquid or gas with a hydrogen sulfide scavenger (US 2004/0096382 A1) obtained by reacting a compound containing carbonyl groups with an alcohol, thiol, amide, thioamide, urea or thiourea. A compound containing carbonyl groups, preferably formaldehyde. The product is obtained by reacting formaldehyde with an amine-free alcohol or urea (ethylene glycol, propylene glycol, glycerin, diethylene glycol, triethylene glycol, ethyl alcohol, n-butanol, sugar, low molecular weight polyvinyl alcohol, castor oil and urea fatty acids). The scavenger is used with amines, for example monoethanolamine. The reaction product with ethylene glycol.

In a typical procedure, one mole of ethylene glycol is reacted with two moles of formaldehyde in the presence of mineral acid (0.1-10% or <0.1%) as a catalyst. Water can be removed by distillation to finally complete the reaction. It has also been found that the reaction can easily proceed without a catalyst. The resulting product can be neutralized or alkalized to improve stability.

Mercaptans and / or hydrogen sulfide in hydrocarbons, oil, gasolines can be absorbed by introducing an absorber containing at least one azodicarboxylate of the formula R ₁ OOCN = NCOOR ₂ , where R ₁ and R _{2 are} independent alkyl, alkenyl or aromatic groups containing from 1 to 18 carbon atoms (patent WO 2009/126790 A1).

Known hydrogen sulfide scavenger for polysulfide products and a method for the absorption of hydrogen sulfide from polysulfide products WO 01/70679 A1) based on glycetyl ether of the following general formula:

,

,

where R C _2-12 alkyl, allyl or phenyl.

Glycetyl ethers are selected from the group consisting of allyl glycetyl ether, isopropyl glycetyl ether, tert-butyl glycetyl ether, phenyl glycetyl ether and ethyl hexyl glycetyl ether. Tert-butyl or ethylhexylglycetyl ether is preferred due to their low volatility and toxicity, with ethylhexyl glycetyl ether being most preferred.

A known method of reducing the amount of hydrogen sulfide contained in crude oil, which includes adding a hydrogen sulfide scavenger to crude oil, the composition of which includes glyoxal and quaternary ammonium salt (WO 2010/027353 A1).

Closest to the claimed product is the product according to patent WO 2008/027721, according to which the removal of hydrogen sulfide and other sulfohydryl compounds from a gas stream, such as natural gas or a hydrocarbon liquid, is achieved using an absorbing agent having hydroxyalkyl or alkylamine functional groups. The absorber has a higher hydrogen sulfide capacity compared to absorbers having only hydroxyalkyl functional groups.

The absorber is a triazine with hydroxyalkyl and alkylamine functionality, having the following structure:

In this structure, R is independently selected from the groups consisting of C ₁ -C ₂₀ linear or branched alkyl groups, or R ₁ OH, where R ₁ -C ₁ -C _{20 are} linear or branched alkylene groups. At least one R group is a C ₁ -C ₂₀ linear or branched alkyl group and at least one R group is R ₁ OH.

Preferred alkyl amines are methylamine, ethylamine, propylamine, isopropylamine, butylamine, isobutylamine and mixtures thereof. Preferred alkanolamines include ethanolamine (2-aminoethanol), isopropylamine (1-amino-2-propanol), aminomethylpropanol (2-amino-2-methylpropanol), tris-hydroxymethylmethylamine (2-amino-2-hydroxymethyl-1,3-propanediol) and mixtures thereof.

In one non-limiting embodiment, the absorbing agent is obtained by reacting formaldehyde with at least one primary amine and at least one alkanolamine, while the molar ratio of formaldehyde to the total amount of amines ranges from 2: 1 to 1: 2. In other versions, the ratio may vary from 1.5: 1 to 1: 1.5 and from 1.15: 1 to 1: 1.15. The molar ratio of alkylamine to alkanolamine can vary from 1:99 to 99: 1.

A common disadvantage of all the described inventions is that the claimed compositions either include formalin and / or various amines, or absorbents obtained by synthesis of the starting components in the stated molar ratios, also contain unreacted formalin and / or amine, which themselves have an increased danger to human health.

Formaldehyde is a pungent odor. It is included in the list of carcinogens, has chronic toxicity, negatively affects genetic material, reproductive organs, respiratory tract, eyes, and skin. It has a strong effect on the central nervous system. It can also potentially cause asthma and asthma attacks as a non-specific irritant. Recent medical examinations of people at occupational risk suggest that formaldehyde causes cancer in humans.

In terms of toxicity, formaldehyde belongs to highly hazardous substances of hazard class 2 (similar to chlorine, dichloroethane, carbon disulfide, etc.). The maximum permissible concentrations of formaldehyde are extremely small:

- for the air of settlements, the maximum permissible maximum one-time concentration of formaldehyde is MPCm.r. = 0.035 mg / m ³ ;

- the maximum allowable daily average concentration of MPC.s. = 0.003 mg / m ³ ;

- the maximum permissible concentration of formaldehyde in the air of the working area - MPC = 0.5 mg / m ³ .

The lethal dose of a 35% solution of formaldehyde (formalin) is from 10 to 50 g.

Amines are also very toxic substances. Almost all amines are highly hazardous substances of hazard class 2. Inhalation of their fumes and contact with skin are dangerous. Amines are able to be absorbed through the skin into the bloodstream and disrupt hemoglobin functions, which can lead to death. Symptoms of amine blood poisoning are blue fingertips, nose, lips, shortness of breath, rapid breathing and palpitations, loss of consciousness.

The objective of the present invention is to provide an absorber of hydrogen sulfide and volatile mercaptans, which, having a high binding ability with respect to active sulfur compounds (hydrogen sulfide and volatile mercaptans), does not contain free formalin and amines and is classified as moderately hazardous hazard class 3 hazard class.

To solve this problem, a hydrogen sulfide scavenger is proposed, which is a composition of 1,3,5-tri - (- hydroxyethyl) -hexahydro-S-triazine (compound I), hydroxymethylurea (compound II) and 1,3-bis (hydroxymethyl urea (compound III) in an organic solvent (compound IV).

Fatty alcohols of the general formula ROH, where R — C ₁ —C ₄ , glycols of the general formula HOCH ₂ CHROH, where RH or C ₁ —C ₂ , cellosolves ROCH ₂ CH ₂ OH, where R — C ₁ —C, are used as an organic solvent. ₄ .

The structure of the compounds that make up the composition is presented below.

The ratio of compounds that make up the reagent:

- compound I - 1,3,5-tri - (- hydroxyethyl) -hexahydro-S-triazine - 68-88% wt.

- compound II - 1.5-4.5% wt.

- compound III - 0.5-2.5% wt.

- compound IV - 10-25% wt.

According to the present invention, a hydrogen sulfide scavenger reagent is obtained by reacting monoethanolamine with paraformaldehyde in a molar ratio of components of 1: 1-1: 1.07 at temperatures of 30-60 ° C with stirring for 3-7 hours with further addition of urea to the reaction mass 2.5-4.5% per reaction mass and with the further addition of an organic solvent.

The introduction of urea into the reaction allows you to bind free paraformaldehyde, which is introduced into the reaction in a small excess to ensure the completeness of the reaction and to ensure the absence of a free amine.

The following examples illustrate the proposed technical solution, without limiting it.

Example 1

183.0 g (3 mol) of monoethanolamine are charged into a flask equipped with a mechanical stirrer and a reflux condenser, while stirring over 2 hours, 91.8 g of paraformaldehyde (3.06 mol) is added so that the temperature of the reaction mixture does not rise above 30 ° C. After the addition is complete, the reaction mixture is heated to 50 ° C and maintained at this temperature until the paraformaldehyde residues are completely dissolved (within 1-2 hours). Next, the reaction mass is cooled to 25 ° C, add 40 g of methanol, mix for 15 minutes, then add 3.6 g of urea (0.06 mol) and mix until completely dissolved (30-60 minutes).

Example 2

183.0 g (3 mol) of monoethanolamine are charged into a flask equipped with a mechanical stirrer and reflux condenser, 94.5 g of paraformaldehyde (3.15 mol) is added over 2 hours with stirring so that the temperature of the reaction mixture does not rise above 30 ° C. After the addition is complete, the reaction mixture is heated to 50 ° C and maintained at this temperature until the paraformaldehyde residues are completely dissolved (within 1-2 hours). Next, the reaction mass is cooled to 25 ° C, 40 g of methanol are added, stirred for 15 minutes, then 9.0 g of urea (0.15 mol) is added and stirred until complete dissolution (30-60 minutes).

Example 3

183.0 g (3 mol) of monoethanolamine are charged into a flask equipped with a mechanical stirrer and reflux condenser, 96.3 g of paraformaldehyde (3.21 mol) are added with stirring over 2 hours so that the temperature of the reaction mixture does not rise above 30 ° C. After the addition is complete, the reaction mixture is heated to 50 ° C and maintained at this temperature until the paraformaldehyde residues are completely dissolved (within 1-2 hours). Next, the reaction mass is cooled to 25 ° C, 40 g of methanol are added, stirred for 15 minutes, then 12.6 g of carbamide (0.21 mol) is added and stirred until complete dissolution (30-60 minutes).

Example 4

183.0 g (3 mol) of monoethanolamine are charged into a flask equipped with a mechanical stirrer and reflux condenser, 94.5 g of paraformaldehyde (3.15 mol) is added over 2 hours with stirring so that the temperature of the reaction mixture does not rise above 30 ° C. After the addition is complete, the reaction mixture is heated to 50 ° C and maintained at this temperature until the paraformaldehyde residues are completely dissolved (within 1-2 hours). Next, the reaction mass is cooled to 25 ° C, 40 g of ethylene glycol are added, stirred for 15 minutes, then 9.0 g of urea (0.15 mol) is added and stirred until complete dissolution (30-60 minutes).

Example 5

183.0 g (3 mol) of monoethanolamine are charged into a flask equipped with a mechanical stirrer and reflux condenser, 96.3 g of paraformaldehyde (3.21 mol) are added with stirring over 2 hours so that the temperature of the reaction mixture does not rise above 30 ° C. After the addition is complete, the reaction mixture is heated to 50 ° C and maintained at this temperature until the paraformaldehyde residues are completely dissolved (within 1-2 hours). Next, the reaction mass is cooled to 25 ° C, 40 g of methyl cellosolve are added, stirred for 15 minutes, then 10.2 g of carbamide (0.17 mol) is added and stirred until complete dissolution (30-60 minutes).

Example 6

183.0 g (3 mol) of monoethanolamine are charged into a flask equipped with a mechanical stirrer and reflux condenser, 96.3 g of paraformaldehyde (3.21 mol) are added with stirring over 2 hours so that the temperature of the reaction mixture does not rise above 30 ° C. After the addition is complete, the reaction mixture is heated to 50 ° C and maintained at this temperature until the paraformaldehyde residues are completely dissolved (within 1-2 hours). Next, the reaction mass is cooled to 25 ° C, 40 g of butyl cellosolve are added, stirred for 15 minutes, then 10.2 g of carbamide (0.17 mol) is added and stirred until complete dissolution (30-60 minutes).

Example 7 (without the addition of urea)

183.0 g (3 mol) of monoethanolamine are charged into a flask equipped with a mechanical stirrer and a reflux condenser, while stirring over 2 hours, 91.8 g of paraformaldehyde (3.06 mol) is added so that the temperature of the reaction mixture does not rise above 30 ° C. After the addition is complete, the reaction mixture is heated to 50 ° C and maintained at this temperature until the paraformaldehyde residues are completely dissolved (within 1-2 hours). Next, the reaction mass is cooled to 25 ° C, then add 40 g of methanol and mix until smooth (15-20 min).

The following products were used as reference samples:

- example 8 (comparison sample) - commodity reagent NTN-50 TU 2411-014-48090685-2005, is a solution of paraformaldehyde (50 + 2% wt.) in an organic solvent;

- example 9 (comparative example) - commodity reagent Koltek PS 1615 TU 0251-005-17423242-2003, is a specially selected composition of alkyl amines and / or products of the condensation of amines with aldehydes in a hydrocarbon solvent;

- example 10 (comparison sample) - the sample is synthesized according to the closest to the claimed patent WO 2008/027721, obtained by the interaction of ethanolamine with formaldehyde in a molar ratio of components of 1: 1.2.

All samples were tested for their effectiveness - the ability to bind hydrogen sulfide in fuel oil.

Study of the effectiveness of the action of reagents-absorbers of hydrogen sulfide.

A method for evaluating the effectiveness of a hydrogen sulfide scavenger is to measure the hydrogen sulfide content in commercial fuel. The determination of the initial and residual hydrogen sulfide content was carried out according to the method IP 399/94 "Determination of hydrogen sulfide content in liquid fuels".

The absorber was introduced into a sample of commercial fuel oil under the following conditions, temperature 80 ° C, mixing time 1 hour, mixing speed 1200 rpm.

During the tests, commercial fuel oil produced by Moscow Refinery OJSC (MNPZ) with an initial hydrogen sulfide content of 71 ppm and commercial fuel oil produced by Ryazan NPK CJSC (RNPK) with an initial hydrogen sulfide content of 7.62 ppm were used. The test data are presented in table 1.

The residual content of hydrogen sulfide in fuel oil - less than 2 ppm is considered absent.

From table 1 it can be seen that all the studied samples of hydrogen sulfide absorbers are used in concentrations of 5-10 ppm reagent per 1 ppm of hydrogen sulfide. Moreover, the efficiency of the samples synthesized according to the invention is either at or slightly higher than that of the comparison samples.

Table 1 Data on the results of checking the effectiveness of the action of reagents-absorbers of hydrogen sulfide. Example for example Absorber sample concentration, ppm absorber / ppm H ₂ S Fuel oil manufacturer The initial content of hydrogen sulfide in heating oil, ppm The residual content of hydrogen sulfide in heating oil, ppm one 5 MNPZ 71 2.98 one 10 MNPZ 71 1.95 2 10 MNPZ 71 1.90 3 10 MNPZ 71 1.92 four 10 MNPZ 71 1.90 5 10 MNPZ 71 1.91 6 10 MNPZ 71 1.91 7 (no carbamide added) 10 MNPZ 71 1.93 8 (comparison sample) 10 MNPZ 71 1.90 9 (comparison sample) 10 MNPZ 71 2.9 69 (sample comparison) fifteen MNPZ 71 1.97 10 (comparison sample) 10 MNPZ 71 2.0 one 10 RNPK 7.62 0.37 one 5 RNPK 7.62 0.74 2 5 RNPK 7.62 0.64 3 5 RNPK 7.62 0.55 four 5 RNPK 7.62 0.63 5 5 RNPK 7.62 0.62 6 5 RNPK 7.62 0.61 7 (no carbamide added) 5 RNPK 7.62 0.57 8 (comparison sample) 5 RNPK 7.62 0.25 9 (comparison sample) 5 RNPK 7.62 2.95 9 (comparison sample) 10 RNPK 7.62 1.15 10 (comparison sample) 5 RNPK 7.62 2.15 10 (comparison sample) 10 RNPK 7.62 1,57

Checking samples for the presence of free formaldehyde.

The samples were checked for the presence of free formaldehyde by nuclear magnetic resonance analysis on a Broker AM-300 instrument (300 MHz), D ₂ O.

The ¹³ C spectra of samples 1, 2, 3, 4, 5, and 6 (the structure is given above) contain 54 ppm (C3), 58 ppm (C2), and 73 ppm (C1) signals.

Free formaldehyde signals (82 ppm) were not observed in the spectra.

At the same time, this signal is present in the spectra of samples 8, 9, and 10. In sample 7, there are traces.

Simultaneously, the samples obtained in examples 1-10 were investigated by infrared and ultraviolet spectroscopy.

In the IR spectra of samples 8, 9 and 10 there is a characteristic band of 1740 cm ^-1 , which indicates the presence of free formaldehyde. The same band in the spectrum of sample 7 is weak, which indicates the presence of formaldehyde in an insignificant amount. In the spectra of samples 1, 2, 3, 4, 5, and 6, the characteristic band of formaldehyde is absent.

In the UV spectra of samples 1, 2, 3, 4, 5, and 6, there is no band of the carbonyl group of 280 nm, clearly expressed in the spectra of samples 8, 9, and 10; in sample 7 it is weakly expressed.

All research data show that all comparison samples (8-10), as well as sample 7 (obtained without the addition of urea) incorporate free formaldehyde. In this case, sample 8 (even according to TU standards) is 50% wt. consists of paraformaldehyde.

Samples 1-6 do not contain free formaldehyde.

The absence of free formalin in the sample synthesized according to the present invention is confirmed by the data of the sanitary-epidemiological conclusion No. 50.RA.02.025.P.00802.05.10 from 05/13/2010 (formaldehyde was not found).

Claims (1)

The reagent is an absorber of hydrogen sulfide and volatile mercaptans in liquid fuels, which is a composition comprising 1,3,5-tri - (- hydroxyethyl) -hexahydro-S-triazine (compound I), hydroxymethylurea (compound II) and 1,3-bis (hydroxymethyl) urea (compound III) in an organic solvent (compound IV) at a concentration of 68-88, 1.5-4.5, 0.5-2.5, 10-25 wt.%, respectively, the structure of which is presented below