The method of producing gasoline from hydrocarbon gas feedstock

 

(57) Abstract:

Usage: petrochemistry. Essence: eco-friendly high-octane gasoline is produced by a synthesis gas, diluted or not diluted ballast nitrogen, one-step catalytic synthesis of dimethyl ether from synthesis gas, the synthesis of gasoline from gases of the second stage of the process and extraction of gasoline from the gas stream. 11 C. p. F.-ly, 1 table.

The present invention relates to the field of petrochemical and refining industries, and more specifically to the field of synthetic motor fuel from gaseous hydrocarbons.

The problem of obtaining liquid products for various purposes from gaseous hydrocarbons for decades is in the field of view of researchers virtually all industrialized countries of the world. Relative to the direction of the fuel processing hydrocarbon gases economists usually say that such a production in itself is at the limit of profitability and can not compete with fuels derived from oil. At the same time, it is noted that the fuel market can take almost any amount of gasoline and">

The economic aspect of the problem should also take into account the cost parameters for motor fuels in remote and inaccessible areas, as well as environmental problems associated with a large number of associated petroleum gases, often flared, particularly on offshore platforms. Another aspect of ecology in light of the possibility of using synthetic motor fuels is their advantage over fuel oil in relation to the exhaust gas.

For these reasons, in the last years of the twentieth century interest in the industrial use of hydrocarbon gas as raw material for the production of motor fuels received a new impetus in several industrialized countries, including in Russia.

From the analysis of patent and technical literature, implemented in industry the classical scheme for the production of motor fuels from hydrocarbon gas feedstock includes stages for production of synthesis gas for production of liquid hydrocarbon products in one way or another modification of the Fischer-Tropsch synthesis and, finally, the production of motor fuel quality. Know the use of coal as raw materials for the production Sint is in can be obtained in the sequence of processes: the production of synthesis gas, synthesis of oxygen-containing products (methanol or dimethyl ether), the production of gasoline.

Economic analysis of different technological schemes of production of synthetic motor fuels shows that at least 50% of investment in the industrial sector accounted for the stage of synthesis gas production, and its share in the cost of the final product is 55-60%. In this regard, in recent years several companies have paid attention to this stage of technology.

Up to the present time to produce synthesis gas almost exclusively used the process of conversion of methane with steam in the presence of oxygen on the catalyst based on Nickel

CH4+H2O=CO+3H2(1)

This process has two major drawbacks: its intensity and the fact that its implementation requires the creation of a special plant for the production of oxygen. This not only places a heavy burden on the economy, but also increases technical risk. Indeed, it is known that in 1997 on one of the plants to produce synthetic fuels was struck by a devastating explosion at the plant for the production of oxygen. In the presence of oxygen reactions occur

CH4+2O2=CO2+2H22close to two.

To address the first of these disadvantages high energy steam reforming reaction (1) (or, as it is called, steam reforming) were combined in a single device with the power generation reaction partial (partial) oxidation of methane with oxygen (3). This combined process is called "autothermal reforming".

Depending on the excess air coefficient (the ratio of the amount of oxygen in the reacting system to its stoichiometric amount for the reaction of complete oxidation of the hydrocarbon to carbon dioxide and water) the composition of the products of partial oxidation varies widely. At the same time it should be emphasized that the process of partial oxidation when the value of 0.25, which corresponds to the stoichiometry of reaction (3), almost always accompanied by a noticeable creamatorium. Therefore, in practice, the process of partial oxidation is carried out at sverdsrikhimmash values .

Recently it became known option autothermal reforming, in which the partial oxidation is conducted with oxygen, air or air enriched with oxygen is in the process of partial oxidation of methane. This technology firms Texaco Inc. and Royal Dutch/Shell Group has received an industrial application. The process is carried out at high temperatures (1200-1500oC) and pressures (up to 150 ATM). As oxidant on a powerful industrial plants use oxygen.

Method for production of synthesis gas from methane implement application process, high-temperature (1200 K) catalytic carbon dioxide conversion

CH4+CO2-2SD+2H2(4)

This allows you to recycle the carbon dioxide formed in different processes specific chemical production or produced specially.

When it comes to technology dimethyl ether (DME), the one-step method of its production was first developed by company Haldor Topsoe (scale pilot plant). As raw material in this way used a synthesis gas comprising hydrogen, carbon monoxide and minor impurities of other gases. Information about the possibility of the one receiving DME from synthesis gas, in which the addition of carbon monoxide and hydrogen are carbon dioxide and unreacted methane, and ballast nitrogen in the patent and scientific literature is not found.

Final SRA, sent directly (without additional purification and separation) in the reactor to obtain a one-stage high-octane environmentally friendly gasoline. In the patent and scientific literature is not found information about this kind of process.

To some extent, the above method is reminiscent of the famous 80's technology for producing gasoline from methanol company Mobil Oil. The plant in New Zealand, originally built Mobil, and now owned by the company Methanex, currently produces only methanol. This is due, in particular, with the fact that gasoline produced from methanol, the content of aromatic hydrocarbons is usually not less than 50%. Among them benzene, durene and Isadora. Claims ecological character of such gasoline is obvious in the light of international standards Euro-3 (operational since 2000) and Euro-4 (effective from 2005). Indeed, the total amount of aromatic hydrocarbons and benzene content in a gasoline does not meet modern requirements.

The closest analogue of the present invention is a method of obtaining gasoline fraction through the synthesis gas and dimethyl ether according to the U.S. patent 5459166 (1995). This technical solution of prpared and hydrogen, sent to the reactor for the synthesis of dimethyl ether. Then pure dimethyl ether is sent to the reactor for the production of gasoline. To do this he must be isolated from the gas synthesis process (patent not mentioned). Conversion of dimethyl ether is a maximum of 55%. The obtained liquid product on the fractional composition corresponds to the gasoline fraction.

The invention in accordance with the above U.S. patent has a number of disadvantages. First, it should be noted that at all stages to the final product use only high-purity raw materials. This requires a high cost of its preparation and cleanup, and complicates the technological scheme. Secondly, the conversion of dimethyl ether totally inadequate from the point of view of the economy, as about half of dimethyl ether remains unreacted, must be separated from the gasoline and returned to the process. In addition, the ratio of the yields of the target products (gasoline fraction) and gas, i.e., the selectivity of the process, also has not been satisfactory.

In conclusion, it should be noted that in the patent no information characterizing the final product and showing prakticheskoy fraction, it must be at least minimally, characterized by such indicators as the octane number, the total content of aromatic hydrocarbons and, separately, benzene (its content in gasoline, in accordance with the applicable both in the US and Europe regulations, is limited to 1%), and the content of unsaturated hydrocarbons. These data could provide the opportunity to judge ecological perspectives direct use gasoline fraction.

The present invention aims at eliminating the above-mentioned disadvantages of the prototype. It provides for simple and cost-effective technology environmentally friendly high-octane gasoline with a good yield of the final product, satisfying perspective (2005) the requirements of Euro-4 standard.

According to the invention the problem is solved as follows. Get at high pressure synthesis gas containing hydrogen, carbon oxides, water, remaining after its receipt unreacted hydrocarbon and containing or not containing ballast nitrogen, by condensation from synthesis gas into and remove the water and then carry out a gas-phase, adnotatione under pressure is passed over the modified high-silica zeolite for the production of gasoline and cooled gas stream for allocation of gasoline.

Obtaining synthesis gas is carried out in the process of partial oxidation of hydrocarbons under pressure, ensuring its catalytic processing without additional compression.

It can also be obtained by catalytic reforming of hydrocarbons with steam or by autothermal reforming. When this process is carried out at a flow of air, air enriched with oxygen, or pure oxygen.

Synthesis gas can also be obtained by catalytic reforming of natural gas with carbon dioxide.

Raw materials in the process for production of synthesis gas by partial oxidation fed into the reactor after contact with the hot surface of the exterior walls, and contained in the synthesis gas water is removed by condensation to a residual concentration of not more than 0.5% vol.

In the process of implementation of the method of conducting a continuous determination of the oxygen content in the synthesis gas and stop its flow into the reactor dimethyl ether, when the oxygen concentration in the synthesis gas exceeds 0,2 about. %. This synthesis gas is heated to the process temperature synthesis of dimethyl ether by passing it through those who enzina and dimethyl ether is carried out at almost equal pressures.

The process of dimethyl ether and gasoline can be carried out in one reaction apparatus.

So, when receiving the synthesis gas in accordance with one variant of the proposed method for the first time the pressure in the process of partial oxidation of hydrocarbons is uniquely associated with the pressure at the stage catalytic synthesis of dimethyl ether so that the synthesis gas is fed to the catalysis without additional compression. In this respect, the proposed method is significantly different from previously known methods.

Indeed, in all industrial technologies for production of synthesis gas, before it enters the catalytic reactor, komprimiert. It is known that the catalytic synthesis processes, in particular for the methanol synthesis process, the synthesis gas is pre-release from the main mass of the contained water vapor at a relatively low their partial pressure. This operation is performed before compression in order to avoid water hammer in the compressors. Only after that make compression to the pressure required for catalytic conversion of synthesis gas.

In the proposed method considers the ez-gas. Due to this, the allocation of a water vapor occurs at relatively high partial pressure and becomes more effective. For the same reasons increases and the efficiency of desulfurization source components prior to obtaining synthesis gas. At the same time decrease the dimensions of the apparatus in which these processes are.

In the present method for production of ecologically clean high-octane gasoline component part of the sequence of operations is a one-step process of obtaining DME. Obtaining DME from synthesis gas, in which the nitrogen content can exceed 50%, are not described in literature. Not found and the relevant patent data. Meanwhile, the processing technology is highly diluted with an inert component of the synthesis gas has its specificity, associated in particular with a different level of heat and other heat capacity of the gas. Therefore, the above-mentioned one-step process company Haldor Topsoe, based on the use of synthesis gas not containing ballast and other impurities, can not be directly associated with the proposed applicants method.

The final stage of the proposed method is the one getting the wysowa, although obtaining gasoline fraction (not petrol) described in the prototype, but with less selectivity and yield than in the present invention and other raw materials (from dimethyl ether, not containing ballast and other impurities).

The process of obtaining gasoline from dimethyl ether begins with the reaction of his dehydration

(CH3)2O=C2H4+H2ABOUT (5),

as a result of which there is a transition from oxygen-containing product to the hydrocarbon. Then there is a complex sequence of reactions, oligomerization, cyclization, disproportionation and isomerization, which is formed of individual and fractional composition of gasoline.

It seems obvious that the results of the proposed method of production of gasoline, based on the reaction (5), must coincide with process indicators Mobil. From the point of view of General chemistry concepts it really is. However, obtained in accordance with the present invention, the results were totally unexpected and do not fit into the traditional framework.

First, the proposed method obtained only gasoline fraction with the release of 90%. Hydrocarbons boil the Nola, the gasoline produced by the proposed method significantly higher content isoparaffinic significantly (by almost half) lower content of aromatic hydrocarbons. While no such environmentally harmful components, such as benzene, durene and Isadora. These results have important ecological value, taking into account the fact that trends in requirements for fuels for gasoline engines are characterized by limit the allowable content of aromatic hydrocarbons.

Catalytic production of gasoline according to the proposed method is conducted without separating dimethyl ether from natural gas, diluted with large quantities of impurities, inert in the process. This is a significant difference between the proposed method from all other processing technologies of oxygen-containing compounds in petroleum products.

The following are examples of the method, illustrating the invention, but not limiting of its scope.

Examples .

Example 1.

Methane and air were kompiliroval separately to a pressure exceeding the pressure in the partial oxidation reactor. After the standard adsorption from the products of partial oxidation. The mixing of components was carried out directly in the reaction zone (as a variant to this area). In this experiment, the coefficient of excess air in the methane-air mixture was 0,387.

In a flow reactor spent the partial oxidation of methane with oxygen at a pressure of 54 bar and the maximum temperature in the reactor of about 1200 K, the resulting synthesis gas was passed through a heat exchanger located between the partial oxidation reactor and a block allocation of water. Conducted Isobaric cooling the synthesis gas to condense water. The residual water content in the synthesis gas was 0.5 vol.%. The resulting synthesis gas is heated at constant pressure until the temperature of the beginning of the synthesis of dimethyl ether (500 K) and served in a flow catalytic reactor, where the working pressure was 50 bar. The obtained gas mixture containing the target product dimethyl ether was heated to a temperature of about 700 K and sent to the catalytic flow reactor filled with a modified high-silica zeolite, which made the synthesis of gasoline. Coming out of the reactor, the gas stream containing the target product gas was cooled to highlight gasoline Hildren from pressure, selected in the partial oxidation reactor can be submitted directly to the reactor after separation of water, if the pressure of the synthesis gas is greater than the pressure in the synthesis reactor DME, or otherwise, must be further compressed.

The methane content in the mixture was varied in the range of values of the excess air coefficient from 0.35 to 0.55.

The resulting synthesis gas, while maintaining an approximately constant pressure, cooled to select from it water vapor to a level not in excess of 0.4-0.5 vol.%. Then freed from excess moisture synthesis gas is heated in the heat exchanger. When the ratio of methane/air, the appropriate value =0,41 derived synthesis gas (after drying) had the following composition: CO - 13,2%, H2- 21,7%, CO22.5%, AND CH4- 2,7%, nitrogen up to 100%.

Diluted with nitrogen synthesis gas, the composition of which is given above, was filed in the catalytic reactor, in which at a pressure of 50 ATM over a combined synthetic-dehydrating catalyst was the synthesis of DME.

Outputs DME depend on the amount of CO in the synthesis gas, pressure and other process conditions. At 50 bar up to 65-70% of the carbon goes into the DME, which is close to its equilibrium copaamerica or in any other way, and then fed into a catalytic reactor for the synthesis of gasoline. The process was carried out at the same pressure (50 ATM), and the synthesis of DME. Conversion of DME was almost 100%, the yield of gasoline fraction of 91.5%, the yield of dry gas (C1-C3) was 8.5%.

It is important to note that gasoline is obtained according to the proposed method, on such an important ecological characteristic as the sulfur content (less than 0.5 ppm), significantly exceeds that of all types of fuels for gasoline engines. The table contains data, confirming its high quality.

Example 2.

Methane and air were kompiliroval separately to a pressure exceeding the pressure in the partial oxidation reactor. After the standard desulfurization methane source components passed through the heat exchangers, in which they were heated by the heat of the products of partial oxidation. The mixing of components was carried out directly in the reaction zone. The methane content in the mixture was varied in the range of values of the excess air coefficient from 0.35 to 0.55.

When the pressure in the reactor partial oxidation greater than that in the reactor for the synthesis of dimethyl ether, obtained synthesis gas used in two ways. In pellaeon - the resulting synthesis gas, while maintaining an approximately constant pressure, cooled to select from it water vapor to a level not exceeding 0,4-0,5 about. %. Then freed from excess moisture synthesis gas is heated in the heat exchanger. When the ratio of methane/air, the appropriate value =0,41 derived synthesis gas (after drying) had the following composition: CO - 13,2%, H2- 21,7%, CO32.5%, AND CH4- 2,7%, nitrogen up to 100%.

Diluted with nitrogen synthesis gas, the composition of which is given above, was filed in the catalytic reactor, in which at a pressure of 50 ATM over a combined synthetic-dehydrating catalyst was the synthesis of DME. Outputs DME depend on the amount of CO in the synthesis gas, pressure and other process conditions. At 50 bar up to 65-70% of the carbon goes into the DME, which is close to its equilibrium content in these conditions.

The gas obtained in the catalytic reactor for the synthesis of DME were heated in the heat exchanger or in any other way, and then fed to the catalytic reactor for the synthesis of gasoline. The process was carried out at the same pressure (50 ATM), and the synthesis of DME. Conversion of DME was almost 100%, the yield of gasoline fraction ranged from 91.5%, and the yield of dry gas (C1-C3

Example 3.

All the conditions of example 1 are left unchanged, except under the conditions of mixing the starting components at the entrance to the partial oxidation reactor. They were mixed in a special mixer to feed in the reaction zone. If this were obtained, in General, similar results but to a residual content of methane in the synthesis gas decreased from 2.7 to 2.3%.

Example 4.

As a source of raw materials used hydrocarbon gas composition of CH4- 86,9%, WITH2H6TO 10.1%, C3H8- 3%. At the same time (after drying) was obtained synthesis gas of the following composition: CO - 14,1%, N2- 21,5%, CO2- 2,9%, the content of residual methane was 2.9%. The increase in CO had a favourable impact on the product yield of the process, which increased almost proportionally to the increase in CO in the synthesis gas, i.e., Rel. 7%.

Example 5.

Under conditions analogous to example 1, synthesis of dimethyl ether was carried out at a pressure of 100 ATM. Up to 85% of the carbon FROM the passed in DME, which is close to ravnovesie gas received partial oxidation of methane with oxygen at elevated up to 52 ATM pressure and maximum temperature in the reactor of about 1600 To flow chemical reactor with cooled walls, created on the base of the rocket engine. The process was carried out at =0,425. The composition of the synthesis gas after drying was as follows (vol.%): hydrogen - 53,0; CO - 39,9; CO2- 5,8; CH4- 1,3;/N2=0,75.

Further procedures were performed as described in example 1, i.e. in the first catalytic reactor at a pressure of 50 atmospheres used combined synthesizing-dehydrating catalyst, with about 70% of the carbon goes into DME. The gas stream from the catalytic reactor for the synthesis of DME were heated in a heat exchanger and fed into a catalytic reactor for the synthesis of gasoline at the same pressure. The composition of the obtained products was not significantly different from the composition of the products obtained in example 1.

Example 7.

Synthesis gas received partial oxidation of methane with oxygen at elevated up to 53 ATM pressure and maximum temperature in the reactor of about 1640 in flow chemical reactor with cooled walls, created on the base of the rocket engine. The process was carried out at =0,445. The composition of the synthesis gas after drying was as follows (vol.%): hydrogen - 55; CO - 38,4; CO2- 6; CH4- 0,6;/N2=0,7. Follow-up procedures and the composition of the products obtained, as in example 6.

1. Spoonerized, characterized in that the gain at high pressure synthesis gas containing hydrogen, carbon oxides, water, remaining after its receipt unreacted hydrocarbon and containing or not containing ballast nitrogen, by condensation from the specified synthesis gas is isolated and remove the water and carry out gas-phase, single-stage catalytic synthesis of dimethyl ether, the obtained gas mixture without separating dimethyl ether under pressure is passed over the modified high-silica zeolite for the production of gasoline and cooled gas stream for allocation of gasoline.

2. The method according to p. 1, characterized in that the synthesis gas produced in the process of partial oxidation of hydrocarbons under pressure, ensuring its catalytic processing without additional compression.

3. The method according to p. 1, characterized in that the synthesis gas obtained by the catalytic reforming of hydrocarbons with steam.

4. The method according to p. 1, characterized in that the synthesis gas obtained by autothermal reforming.

5. The method according to p. 2 or 4, characterized in that the process is performed in air, or air enriched kislorodchiki reforming of natural gas with carbon dioxide.

7. The method according to p. 1 or 2, characterized in that the raw materials of the process for production of synthesis gas by partial oxidation fed into the reactor after contact with the hot surface of external walls.

8. The method according to p. 1, characterized in that contained in the synthesis gas water is removed by condensation to a residual concentration of less than 0.5. %.

9. The method according to p. 1, characterized in that conduct continuous determination of the oxygen content in the synthesis gas and stop its flow into the reactor dimethyl ether, when the oxygen concentration in the synthesis gas exceeds 0,2 about. %.

10. The method according to p. 1, characterized in that the synthesis gas is heated to the process temperature synthesis of dimethyl ether by passing it through a heat exchanger located between the reactor for the synthesis of gasoline and block condensation of gasoline.

11. The method according to p. 1, characterized in that the process of synthesis of gasoline and dimethyl ether is carried out at almost equal pressures.

12. The method according to p. 1, characterized in that the process of dimethyl ether and gasoline is carried out in one reaction apparatus.

 

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FIELD: hydrocarbon manufacturing.

SUBSTANCE: natural gas is brought into reaction with vapor and oxygen-containing gas in at least one reforming zone to produce syngas mainly containing hydrogen and carbon monoxide and some amount of carbon dioxide. Said gas is fed in Fisher-Tropsh synthesis reactor to obtain crude synthesis stream containing low hydrocarbons, high hydrocarbons, water, and unconverted syngas. Then said crude synthesis stream is separated in drawing zone onto crude product stream containing as main component high hydrocarbons, water stream, and exhaust gas stream, comprising mainly remained components. Further at least part of exhaust gas stream is vapor reformed in separated vapor reforming apparatus, and reformed exhaust gas is charged into gas stream before its introducing in Fisher-Tropsh synthesis reactor.

EFFECT: increased hydrocarbon yield with slight releasing of carbon dioxide.

7 cl, 3 dwg, 1 tbl, 5 ex

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