EA010151B1 - Method of purifying hydrocarbon mixtures from methanol - Google Patents

Abstract

A method for purification of hydrocarbon mixture from methanol comprising contacting of at least feed stock at a temperature not exceeding 450°C and volume velocity of supply at least 1 hourwith methanol decomposition catalyst or methanol conversion catalyst into hydrocarbons and water in corresponding conditions of methanol conversion.The method can be used in oil refining and petrochemistry.

Description

The invention relates to methods for the purification of hydrocarbon mixtures and can be used in refining and petrochemistry.

Methanol is used as an inhibitor of hydrate formation in gas fields. In field conditions, well production is divided into gas, unstable gas condensate and water-methanol mixture. The water-methanol mixture is separated from the condensate of wells by the separation method (Bekirov TM, Danchakov G. A. Gas and condensate treatment technology. M .: Nedra, 1999, p. 332) Part of the methanol, however, is dissolved in the gas and in the hydrocarbon condensate, and in some cases it is necessary to clean the hydrocarbon mixtures from methanol.

A known method of removing polar components from a solution of liquid components according to patent I8 No. 3922217, 25.11.1975, C 106 25/00 (prototype) when the solution comes in contact with a macroporous or gel-like cation-exchange resin containing at least 1% water, which also separates the mixture of hydrocarbons from resin and its regeneration eluting agent. As impurities, the hydrocarbon mixture may contain from 10 ppm to 10% of alcohols, glycols, sulfur oxides, esters, amides, aldehydes, and other polar components. The disadvantage is the high consumption of the elution liquid: its volume is more than twice the volume of the processed hydrocarbon mixture.

From PCT application νθ 97/40121, 10/30/1997, C 106 25/00, a method is known for removing oxidized components from hydrocarbon mixtures containing 3-8 carbon atoms, including their adsorption on an adsorbent containing silica gel, at a temperature of 0-150 ° С, pressure up to 20 atm, and the regeneration of the adsorbent in a stream of inert gas at a temperature of 100-200 ° C.

When used for the extraction of methanol from hydrocarbon mixtures of adsorbents - silica gel and zeolites - their large volume and frequent regeneration is required due to the non-selective adsorption of methanol.

It is known that methanol is converted into a mixture of hydrocarbons and water upon contact with microporous acid catalysts - zeolites (Kapustin MA, Nefedov BK Technological processes for the production of high-octane gasoline from methanol. M., TSNIITEneftekhim, 1982) and silica-alumino phosphates. When methanol comes into contact with a catalyst containing a zeolite of the pentasil group, at a temperature above 370 ° C and a space velocity of about 1 h ^-1, its almost complete conversion into a mixture of C ₁ -C ₁₀ hydrocarbons (56.2%) and water (43.8 %). With increasing temperature, the content of gaseous hydrocarbons in the composition of the product increases.

Microporous crystalline silica-alumino phosphates with molecular sieve properties, the synthesis and structure of which are described in I8 patent No. 4499327, 12.02.1985, C 07 C 01/00, are known as highly selective catalysts for the synthesis of C ₂ -C ₄ olefins from methanol, dimethyl ether, ethanol or diethyl ether . Raw materials may contain as a diluent water, nitrogen, helium, paraffin or an aromatic component to increase the selectivity of the formation of olefins. The method of producing olefins is carried out at a temperature of 200-700 ° C, a pressure of 0.1-1000 atm, with a volumetric feed rate of 0.01-100 h ^-1 .

A catalytic method for the purification of hydrocarbon mixtures from methanol is proposed, including the catalytic conversion of methanol under conditions of the stability of hydrocarbons in the feedstock. The method of purification of a hydrocarbon mixture from methanol includes its contact with a solid porous phase and is characterized in that a catalyst for decomposing methanol or a catalyst for converting methanol to hydrocarbons and water is used as a solid porous phase and at least part of the hydrocarbon mixture is contacted with a catalyst under appropriate conditions of methanol conversion , with a volumetric feed rate of 1-15 h ^-1 .

Methanol-containing raw materials include hydrocarbon gases and gasoline hydrocarbons and are usually WFLH and gas condensates. The methanol content in the hydrocarbon mixture is not limited, but in practice its content does not exceed 1% m. The raw material may include water, in which case it is separated from the raw material before cleaning or after contacting the methanol-containing raw material with the catalyst. The presence of water in the feed does not affect the conversion of methanol. In the preferred case, a fraction with a high methanol content is separated from the liquid hydrocarbon mixture and this fraction is purified. For example, during the distillation of gasoline, methanol is concentrated in a fraction of 40-80 ° C.

The choice of the application of the proposed method of purification of hydrocarbon mixtures from methanol depends on the composition of the raw materials, the content of methanol in it and the requirements for the methanol content in the product.

The decomposition of methanol in a mixture of hydrocarbons is carried out on the known catalysts used for the synthesis of methanol, at a temperature of 220-400 ° C, at a pressure of up to 1.8 MPa, with a bulk feed rate of 1-15 h ^-1 . Preferably the use of low-temperature copper-zinc (copper-zinc-chromium or copper-zinc-aluminum) catalysts for the purification of sulfur-free hydrocarbon mixtures at temperatures of 220-270 ° C or zinc-chromium catalysts at temperatures of 330-400 ° C. The composition, method of preparation of these catalysts and methods for their reduction are known (Karavayev MM, Leonov VE, etc. Synthetic methanol technology. M .: Chemistry, 1984, pp. 51-60).

The catalysts can be used in reduced or non-reduced form. If necessary, the reduction of catalysts before their use for the purification of raw materials is carried out by known methods using hydrogen, carbon monoxide or

- 1 010151 methanol mixed with inert gases. When using a non-reduced catalyst, it is reduced by methanol upon contact with methanol-containing raw materials.

The heating of the catalyst and its drying is preferably carried out on contact with non-oxidizing heated gases — dry hydrocarbon gases, nitrogen, or their mixtures.

When using a non-reduced zinc-chromium catalyst as it is reduced by the raw material methanol, it can be periodically oxidized using known methods of passivating methanol synthesis catalysts in contact with nitrogen or water vapor containing oxygen. Before oxidation, hydrocarbons and decomposition products of methanol are blown off from the surface of the cooled catalyst with an inert gas or water vapor, into which the oxidant is then supplied with oxygen of air and stepwise oxidation of the catalyst is carried out with a gradual increase in temperature, preferably not higher than 420 ° C.

The contact conditions of the feedstock with the catalyst in the preferred case provide the desired degree of conversion of methanol without the conversion of hydrocarbons. So, the higher the temperature of contact of the methanol-containing raw material with the catalyst (from the operating temperature range of the catalyst), the shorter the contact time may be. The hydrocarbon mixture after contact with the catalyst for the decomposition of methanol contains carbon oxides and hydrogen, in some cases - a small amount of gases that can be separated from the liquid raw material after cooling.

The conversion of methanol to hydrocarbons and water is carried out by contacting the feedstock with a catalyst containing a zeolite of the pentasil group, at a temperature of 330-450 ° C, pressure up to 1.8 MPa and at a volume feed rate of the feedstock of 1-15 h ^-1 . Use known catalysts for the synthesis of hydrocarbons from methanol, described, for example, in the review Nefyodova BK, Konovalchikova LD, Rostanina N.N. "Catalysts for oil refining and petrochemistry based on high-silica zeolites", Moscow: TsNIITEneftekhim, 1987, p. 35-52. The catalyst includes zeolites Ζ8Μ-5 and Ζ8Μ-11 in decationized or cation-substituted form and may contain metal cations or metals of the second and third groups of the Periodic Table of the Elements, as well as P, δί and other elements whose compounds are used to reduce the zeolite acidity. The catalyst may be subjected to thermocouple treatment in order to reduce its acidity and increase the stability of its work. As a binder component, the catalyst typically includes alumina or silica. Zeolite content of the catalyst is preferably maximally at sufficient for practical use and the strength of the catalyst is 60-70% m. At temperatures of raw methanol-contact with an acid catalyst occurs cracking and dehydrocyclization of C ₅₊ hydrocarbons and to a lesser extent C3 and C4 hydrocarbons. With a raw material consumption of at least 3 liters per 1 liter of catalyst containing decationized zeolite (its most active form), the conversion of hydrocarbons at 330 ° C or practically does not occur and when the temperature rises only slightly, whereas the residual methanol in the product is less than 0 , 01% or not determined by chromatography. The presence of a small amount of water in a mixture of hydrocarbons does not affect the conversion of methanol. Formed during the conversion of methanol water can be separated from the hydrocarbon mixture in the separator and complete drying of the product can be carried out by known methods, for example, using zeolites. The resulting gases are separated from the liquid product by conventional methods. If the hydrocarbon mixture contains up to 3% of methanol and contains almost no dissolved gases, then when cleaning it under optimal conditions, stabilization of the product is not required.

As the active component of the catalyst for the conversion of methanol to hydrocarbons and water, silica-alumino-phosphate of the type 8ΆΡΘ-34 can be used. The contact of the feedstock with the catalyst is carried out at a temperature of 300-450 ° C, at a pressure of up to 1.8 MPa, at a volumetric feed rate of the feedstock of 1-15 h ^-1 .

Below are examples of the catalytic purification of hydrocarbon mixtures from methanol. Samples of the liquid product were accumulated over 6 hours of catalyst operation and the methanol content was determined by gas chromatography.

Example 1

The gasoline fraction of condensate 42-160 ° C contains 0.03% m. Of methanol. From the gasoline fraction emit a fraction of 42-80 ° C, in which methanol is concentrated. The output of the methanol-containing fraction of gasoline 31%, the methanol content of 0.1% m

The catalyst SNM-1 is dried in a stream of dry gas (methane / ethane = 3.2 l / l) at a temperature of 100-120 ° C. The methanol-containing gasoline fraction is contacted with a low-temperature copper-zinc catalyst for methanol synthesis SNM-1 at 220 ° C, a pressure of 0.2 MPa, and a flow rate of the feed of 1 h ^-1 . The yield of liquid product is 99.0%. Methanol is not detected in it chromatographically.

Example 2

The catalyst SNM-1 is dried in a stream of nitrogen at a temperature of 100-120 ° C and reduced with a mixture of nitrogen and hydrogen (0.7% by volume) at a temperature of 120-200 ° C.

Purification of the methanol-containing fraction of gasoline obtained in Example 1 is carried out by contact with the catalyst SNM-1 at a temperature of 260 ° C, a pressure of 0.2 MPa, and a bulk feed rate of 5 h ^-1 . The methanol content in the liquid product is less than 0.01%. Hydrocarbon gases are not formed in the process.

- 2 010151

Example 3

Purification of the methanol-containing fraction of gasoline obtained in Example 1 is carried out by contact with the recovered industrial high-temperature zinc-chromium catalyst CMC-4 at a temperature of 400 ° C, a pressure of 1.8 MPa, and a flow rate of the feed of 7 h ^-1 . The yield of liquid product is 99.0%. The methanol content in the liquid product is less than 0.01%.

Example 4

Cleaning gas condensate gasoline fraction 60-105 ° C, containing 0.17% methanol, carried out in contact with unrestored catalyst CMC-4 at a temperature of 320 ° C, a pressure of 0.8 MPa, the volumetric feed rate of raw materials 1 h ^-1 . The yield of liquid product is 99.2%. Methanol in the liquid product is not chromatographically determined.

The catalyst is cooled in a stream of nitrogen (volumetric flow rate of 100 h ^-1 ) to 170 ° C and within 8 hours methanol is fed into the nitrogen stream at a flow rate of 0.02 g / h per 1 g of catalyst, raising the temperature to 220 ° C. The restoration of the catalyst is indicated by the absence of water in the stream leaving the reactor. The reduced catalyst is cooled to 150 ° C in a stream of nitrogen and then air is fed into the reactor, raising the oxygen concentration in the stream at the entrance to the reactor to 0.7% and gradually raising the temperature in the reactor over 8 hours to 420 ° C. The end of the oxidation of the catalyst is indicated by the equalization of oxygen concentrations at the inlet to the reactor and at the outlet of the reactor.

In the repeated experiment on purification of gas condensate gasoline fraction of 60-105 ° С on an oxidized catalyst, a liquid product is obtained with a yield of 99.4%, in which methanol is not determined chromatographically.

Example 5

Cleaning the gasoline fraction in example 4 is carried out in contact with unrestored catalyst CMC-4 at a temperature of 340 ° C, a pressure of 0.8 MPa, and a bulk feed rate of 5 h ^-1 . The yield of liquid product is 99.5%. The methanol content in the liquid product is 180 ppm.

Example 6

Purification of the methanol-containing fraction of gasoline obtained in Example 1 is carried out upon contact with a catalyst for the conversion of methanol to hydrocarbons containing 65% m. Zeolite 58е-5 (81О ₂ / Л1 ₂ Oz = 43) and 35% m. A1 ₂ O ₃ , with temperature of 330 ° C, a pressure of 0.7 MPa, a bulk feed rate of 3 h ^-1 . The yield of liquid hydrocarbons is 99.3% m. The methanol content in the product is less than 0.01%.

Example 7

The methanol-containing mixture has the following composition,% m .: methanol - 5, propane - 47, n-butane - 48. Purification of the mixture from methanol is carried out with contact with the methanol conversion catalyst of example 6 at 450 ° C, pressure 1.8 MPa, bulk feed rate of 7 h ^-1 . The yield of liquid hydrocarbons is 95.8% m. The methanol content in the product is less than 0.01%.

Example 8

The methanol-containing mixture according to example 7 is contacted with the catalyst according to example 6 at a temperature of 330 ° C, a pressure of 0.8 MPa, and a bulk feed rate of 1 h ^-1 . The yield of liquid hydrocarbons is 92.6% m. The methanol content in the product is less than 0.01%.

Example 9

The methanol-containing mixture has the following composition,% m .: methanol - 1.5, pentane - 31.3, n-hexane 33.5, n-heptane - 33.7. Purification of the mixture from methanol is carried out in contact with the catalyst for conversion of methanol according to example 6, at a temperature of 360 ° C, a pressure of 0.7 MPa., The volumetric feed rate of the raw material is 5 h ^-1 . The yield of liquid hydrocarbons is 98.6% m. Methanol is not detected chromatographically in a liquid product.

Example 10

Cleaning gas condensate gasoline fraction 60-105 ° C, containing 0.24% methanol, is carried out in contact with a catalyst for the conversion of methanol to hydrocarbons containing 70% sodium-free silica gel 8APO-34 and 30% δίθ ₂ , at a temperature of 360 ° C, pressure 1, 8 MPa, a volumetric feed rate of 5 h ^-1 . The yield of liquid product is 99%. Methanol in the liquid product is not chromatographically determined.

Example 11

Carry out the contact of the gasoline fraction with a catalyst for the conversion of methanol according to example 10, but at a temperature of 450 ° C, a pressure of 0.8 MPa, and a bulk feed rate of 7 h ^-1 . The yield of liquid product is 98%. Methanol in the liquid product is not chromatographically determined.

Example 12

Carry out the contact of the gasoline fraction with a catalyst for the conversion of methanol according to example 10, but at a temperature of 300 ° C, a pressure of 0.8 MPa, and a bulk feed rate of 1 h ^-1 . The yield of the liquid product is 98.1%. The methanol content in the liquid product is less than 0.01%.

Example 13

A gas condensate fraction of 60-90 ° C containing 0.08% of methanol is contacted with the methanol conversion catalyst of Example 10, but at a temperature of 450 ° C, a pressure of 0.4 MPa, and a feed flow rate of 15 h ^-1 . The yield of liquid product is 99.4%. The methanol content in the liquid product

- 3 010151

0.03%.

Example 14

Contact gas condensate fraction 60-90 ° C, containing 0.08% m. Of methanol with reduced in example 2, the catalyst SNM-1 at a temperature of 300 ° C, a pressure of 0.4 MPa, the volumetric feed rate of the raw material 15 h ^-1 . The yield of liquid product is 99.6%. The methanol content in the liquid product is 0.04%.

Claims (7)

1. A method of purifying a hydrocarbon mixture from methanol, comprising contacting it with a solid porous phase, characterized in that a methanol decomposition catalyst or a catalyst for converting methanol to hydrocarbons and water is used as a solid porous phase, and at least part of the hydrocarbon mixture is contacted with the catalyst in appropriate conditions for the conversion of methanol at a temperature of not more than 450 ° C and a volumetric feed rate of at least 1 h ^-1 . 2. The method according to claim 1, characterized in that a fraction containing methanol is isolated from the hydrocarbon mixture and contacted with the catalyst. 3. The method according to claim 1 or 2, characterized in that the reduced or unreduced zinc-chromium or copper-zinc methanol synthesis catalyst is used as a methanol decomposition catalyst, and contact with the methanol-containing hydrocarbon mixture is carried out at a temperature of 220-400 ° C and pressure up to 1.8 MPa. 4. The method according to claim 3, characterized in that the heating of the catalyst and its drying is carried out in contact with heated nitrogen or dry hydrocarbon gas that does not contain oxidizing agents. 5. The method according to claim 3, characterized in that an unreduced zinc-chromium catalyst is used, which is reduced by contact with a methanol-containing hydrocarbon mixture, and the reduced zinc-chromium catalyst is oxidized by contact with nitrogen or water vapor containing oxygen. 6. The method according to claim 1 or 2, characterized in that they use a catalyst for the conversion of methanol to hydrocarbons and water, including a zeolite of the pentasil group, and contact with the methanol-containing hydrocarbon mixture is carried out at a temperature of 330-450 ° C and a pressure of up to 1.8 MPa . 7. The method according to claim 1 or 2, characterized in that they use a catalyst for the conversion of methanol to hydrocarbons and water, including silica-aluminum phosphate type 8APO-34, and contact with the methanol-containing hydrocarbon mixture is carried out at a temperature of 300-450 ° C and a pressure of up to 1, 8 MPa.