RU2358004C1 - Method of refining oil, gas condensate and oil fractions from mercaptans - Google Patents

Abstract

FIELD: mining.

SUBSTANCE: invention refers to method of refining oil, gas condensate and oil fractions from mercaptans by means of catalyst alkali-free liquid phase oxidising de-mercaptanisation at temperature 20-50°C using as catalyst a homogenous liquid composition containing 15-20 wt % of copper chloride or bromide (II), 30-50 wt % of alcohol C₁-C₃ or mixture of the said alcohols, 15-45 wt % of solvating organic additive from row of alkylsulphoxides and alkylamides of linear or cyclic structure, water to 100% - the rest.

EFFECT: increased efficiency of refining.

5 ex, 2 tbl

Description

The invention relates to methods for purifying oil, gas condensate and oil fractions from mercaptans, in particular to catalysts for the oxidative demercaptanization of these products using homogeneous systems based on transition metals. Removal of foul-smelling, toxic and corrosive mercaptans is a necessary condition for using oil fractions as fuel or in the production of chemical products.

To remove mercaptans without the use of expensive and technologically complex hydrotreating, catalytic oxidation is used to form non-toxic and odorless organic disulfides, the so-called oxidative demercaptanization (ODM):

2RSH + 1 / 2O ₂ → RSSR + H ₂ O

Typically, the oxidation is carried out with oxygen or air at room or elevated temperature in the presence of a transition metal catalyst. Widespread, in particular, the so-called. MEROX process developed by UOP. A similar process ODM-DMS-1, developed by the State Unitary Enterprise VNIIUS (RF, Kazan), was implemented at the Tengiz oil field (Kazakhstan). The main disadvantages of this method are the need to use aqueous alkali, a large number of wastewater requiring treatment, and other complicating factors.

A number of ODM catalysts are known that are active only in the presence of aqueous alkalis. In most of these catalytic compositions, cobalt phthalocyanine is intended to be used (for example, European Patent No. 394571, German Patent No. 3008284, etc.). To increase the stability and activity of the catalytic system based on phthalocyanines during the catalytic process, you can use aqueous-alkaline solutions containing polar organic additives, such as primary and secondary water-soluble amines, alkyl amides and mixtures thereof (Russian patent No. 2224006, 2004).

A known method of purification of crude oil by oxidation in an aqueous solution of alkali when heated in the presence of a phthalocyanine catalyst and diethylene glycol and triethylene glycol (USSR AS No. 823418, 1981). The oxidation rate of mercaptans in the presence of these additives increases by 1.2–2 times.

The process of demercaptanization and a catalyst for the oxidation of mercaptans in an aqueous alkali solution during heating based on a phthalocyanine catalyst with polar additives, which use bromides of metals of variable valency I, VI, VII groups of the Periodic system or their complexes with monoethanolamine, are described. The process is carried out with heating and pressure up to 100 atm (AS USSR 3513069, 1974), which complicates the technology.

The known method of ODM by oxidizing mercaptans with atmospheric oxygen in the presence of chelate complexes of a transition metal (Co, Fe, Cu, Ni, Mn) with a multidentate ligand from the class of amides, in particular from aminocarboxypyridines (French patent 2573087). The main disadvantage of the method using such a catalyst is the high cost of its components.

A known catalyst for the purification of petroleum feedstock containing metal salts of variable valency (nickel, manganese, cobalt, copper or iron) or its complex with pyrophosphate or ammonia in combination with secondary or tertiary amines or amino alcohols (Russian patent No. 2167187, 2001). The main disadvantage of this method is the need to use aqueous alkali and a high consumption of nitrogen-containing reagent.

ODM catalysts based on copper complexes with tetracyanothiophenol or tetracyandithiine are proposed (French patent 2591610). The main disadvantage of such catalytic systems is the high cost of the components.

Closest to the described achieved result is the method described in US patent No. 3409543, 1966. According to the patent for the purification of oil fractions, a catalyst based on cobalt and vanadium sulfophthalocyanine and an alkaline solution containing polar organic solvents from the group of dialkyl sulfoxides, amino alcohols, aminohydroxyl esters alkyl amines and alkyl amides. The disadvantage of this method is the complexity of the technology associated with the use of expensive components in the catalyst, the difficulty of its preparation and the need to conduct the process in the presence of aqueous alkali.

The aim of the invention is to simplify the process technology by lowering the cost of the catalyst and avoiding the use of aqueous alkali. The latter will allow to abandon complex operations for the separation and treatment of effluents and will provide a significant reduction in corrosion of equipment.

The problem is achieved by using a homogeneous catalytic composition containing copper (II) chloride or bromide, solvating organic additives from a number of alkyl sulfoxides or alkylamides of linear and cyclic structure, alcohol (C ₁ -C ₃ ) and water. The catalyst is well soluble in oil raw materials without changing the color index, actively oxidizes mercaptans and hydrogen sulfide with atmospheric oxygen at a temperature of 20-50 ° C and atmospheric pressure. All of these components of the catalyst composition are equally necessary, since, for example, replacing copper halide with another salt (nitrate, sulfate, stearate, etc.) leads to a loss of catalyst activity. The refusal to use sulfoxide or amide dramatically reduces the effectiveness of the catalyst and the crude oil turns dark in the first hour of the reaction. If the catalyst composition does not contain alcohol, then its solubility in the substrate is sharply reduced. Removing water from the catalyst leads to the formation of an insoluble precipitate - a complex of copper with sulfoxide or amide.

Thus, a new method of oxidizing alkali-free demercaptanization of oil, gas condensate or oil fractions using a homogeneous catalyst of the above composition obtained by dissolving chloride or copper bromide in an aqueous-alcoholic solution containing 20-30 wt.% Solvating additives is proposed.

The invention is illustrated in examples 1-2. Comparative examples 3-5 illustrate the impossibility of achieving the goal if the composition of the catalyst deviates from that defined in the claims of the invention.

Catalyst Preparation

Example 1

In a 200 ml flat-bottomed flask at room temperature, 50 ml of ethanol, 20 ml of water, 20 ml of DMSO and 15 g of CuCl ₂ · 2H ₂ O are placed. The contents of the flask are stirred with a magnetic stirrer until copper chloride is completely dissolved. The resulting catalyst is a green clear solution. Catalyst A was prepared. Catalysts BE were similarly prepared. Example G illustrates the use of copper bromide instead of chloride. In Example I, diethyl sulfoxide (DESO) was used instead of dimethyl sulfoxide. The composition and parameters of the catalyst preparation process are given in table 1.

Example 2

The catalyst was prepared as in example 1, instead of dimethyl sulfoxide, dimethylformamide was used. Catalysts KM are obtained in this way. In Example H, dimethylacetamide was used instead of dimethylformamide. In Example O, N-methylpyrrolidone was used as a solvating additive.

Table 1
Catalysts for oxidative demercaptanization of oil fractions Catalysis
tor The content in the initial solution, wt.%. Water Alcohol Solvating Additive CuCl ₂ · 2H ₂ O BUT twenty- Ethanol - 55 10 (DMSO) fifteen B 40 Ethanol - 20 20 (DMSO) twenty AT twenty Methanol - 40 25 (DMSO) fifteen G twenty Isopropanol - 45 20 (DMSO) fifteen D twenty Propanol-1 - 40 25 (DMSO) fifteen E twenty Ethanol - 20
Methanol - 25 20 (DMSO) fifteen F * twenty Ethanol 55 20 (DMSO) fifteen AND 40 Ethanol - 55 10 (DESO) fifteen TO twenty Ethanol - 20 45 (DMF) fifteen L twenty Methanol - 20 40- (DMF) twenty M twenty Propanol-1 - 20 40- (DMF) twenty N twenty Ethanol - 20 40-dimethylacetamide twenty O twenty Ethanol - 20 40-N-methylpyrrolidone twenty * - in this example, bromide was used instead of copper chloride.

Catalyst test

(A) Into a reactor with a magnetic stirrer, which is a 350 ml four-necked flat-bottomed flask made of molybdenum glass, equipped with a reflux condenser, an air or oxygen supply system and a glass tube for sampling. A solution of dodecyl mercaptan in isooctane (25 ml) with a sulfur content of 0.18 wt.%, Catalyst A (0.1 ml) and a Teflon magnetic stirrer were placed in the reactor. The reaction time was 2 hours. During this time, the sulfur content decreased to 0.001 wt.%. Sampling was carried out at intervals of 0.5 hours. The content of mercaptans was determined by potentiometric titration according to GOST 17323-71.

(B) The catalyst was tested as in example (A), but mixture G from table 1 containing copper bromide was used as a catalyst. The reaction time was 1.5 hours. During this time, the sulfur content decreased to 0.001 wt.%.

Other catalysts are similarly tested. The test results are shown in table.2.

table 2
Catalyst Test Results Catalysis
tor Refined Oil Product Temperature ° C The content of mercaptan sulfur, wt.% In source After the end of the reaction BUT Solution of dodecyl mercaptan in isooctane 22 0.18 2 hours - 0.001 F Solution of dodecyl mercaptan in isooctane 22 0.18 2 hours - 0.001 BUT Gas condensate * 22 0.13 2 hours - 0.005 BUT Gas condensate 45 0.13 2 hours - 0.005 B Solution of dodecyl mercaptan in isooctane 22 0.18 1 hour - 0.0015 AT Solution of dodecyl mercaptan in isooctane 25 0.18 2 hours - 0.001 G Gas condensate 25 0.13 4 hours - 0.003 D Gas condensate 25 0.13 4 hours - 0.0025 E Solution of dodecyl mercaptan in isooctane 25 0.18 2 hours - 0.001 E Crude oil ** 25 0.23 6 hours - 0.015 AND Solution of dodecyl mercaptan in isooctane 22 0.18 2 hours - 0.001 TO Solution of dodecyl mercaptan in isooctane 22 0.18 2 hours - 0.001 L Solution of dodecyl mercaptan in isooctane 22 0.18 1 hour - 0.0015 AND Gas condensate 45 0.13 2 hours - 0.007 M Solution of dodecyl mercaptan in isooctane 22 0.18 1 hour - 0.0015 N Solution of dodecyl mercaptan in isooctane 22 0.18 2 hours - 0.001 O Solution of dodecyl mercaptan in isooctane 22 0.18 2 hours - 0.0015 * gas condensate was used, distillating in the range 56-354 ° С with a density of 0.77 g / cm ³ and a moisture content of 0.04 wt.%;
** used oil with a density of 0.80 g / cm ³ with a yield of fractions of 28-360 ° C 88%, the content of paraffin hydrocarbons 65%, naphthenic - 26%.

Example 3

The process is conducted, as in example 2, but in the preparation of the catalyst does not use organic solvating additives. 2 hours after the start of work, the content of mercaptan sulfur is 0.08 wt.%, The condensate becomes dark brown.

Example 4

The process is carried out as in example 2, but instead of copper chloride, copper (II) sulfate is used in the preparation of the catalyst. The catalytic composition thus obtained quickly exfoliates, and when it is added to a solution of dodecyl mercaptan in isooctane, a dark precipitate forms. After 5 hours of operation, the concentration of mercaptan sulfur is 0.07 wt.%.

Example 5

The process is carried out as in example 2, but instead of copper chloride, copper (II) stearate is used in the preparation of the catalyst. The resulting catalyst is homogeneous and does not form a precipitate, but its activity is low. After 6 hours of operation, the concentration of mercaptan sulfur in isooctane is 0.06 wt.%.

Claims (1)

The method of purification of oil, gas condensate and oil fractions from mercaptans by catalytic alkali-free liquid-phase oxidative demercaptanization at a temperature of 20-50 ° C using a homogeneous liquid composition containing 15-20 wt.% Copper (II) chloride or bromide as a catalyst, 30-50 wt.% alcohol C ₁ -C ₃ or a mixture of these alcohols, 15-45 wt.% solvating organic additives from a number of alkyl sulfoxides and alkylamides of linear or cyclic structure, the rest up to 100% is water.