CN110183296A - A method of low-carbon alkene co-production gasoline is produced using Fischer-Tropsch synthesis oil - Google Patents

Abstract

The invention provides a method for producing low-carbon olefins by utilizing Fischer-Tropsch synthetic oil and producing gasoline. The C5/C6 fraction in the product obtained by the Fischer-Tropsch synthesis process is introduced into a methanol-to-olefins reactor of a methanol-to-olefins process as a raw material stream , producing light olefins and gasoline products by reacting in a methanol-to-olefins reactor; wherein the C5/C6 fractions introduced into the methanol-to-olefins reactor are used to replace part or all of them for introduction into the methanol-to-olefins reactor Recycle hydrocarbons in ; the lower olefins include ethylene, propylene and/or butene. The method of the invention can effectively couple the Fischer-Tropsch synthesis process and the methanol-to-propylene process, can significantly increase the yield of low-carbon olefins, increase the added value of the C5/C6 fraction in the Fischer-Tropsch synthesis process, and increase the profit of the methanol-to-propylene process .

Description

A method for producing low-carbon olefins and gasoline by utilizing Fischer-Tropsch synthetic oil

technical field

The invention relates to the technical field of producing low-carbon olefins from methanol, in particular to a method for producing low-carbon olefins and gasoline by utilizing Fischer-Tropsch synthetic oil in the process of producing low-carbon olefins from methanol.

Background technique

my country's coal reserves are relatively richer than oil and gas reserves. The industrialization of large-scale conversion of coal into liquid fuels and chemicals in a clean and efficient process will help reduce my country's dependence on imported petroleum resources and improve my country's basic oil and chemicals. self-sufficiency. At present, due to the Fischer-Tropsch synthesis technology has a wide range of raw materials, the products are mainly composed of alkanes and alkenes, as well as the low content of sulfur, nitrogen and aromatic hydrocarbons, clean and environmentally friendly, etc., it has achieved industrial application in my country. The synthetic oil industry will have a production capacity of about 31 million tons per year.

At present, most Fischer-Tropsch synthesis units use liquefied gas, naphtha and diesel components as the main products in the production process. However, for low value-added products such as C5/C6 fractions, there is still no solution to effectively increase their added value.

Light olefins (including ethylene, propylene and/or butene) are important chemical basic raw materials, and their demand is increasing with the growth of the national economy. The traditional production process of low-carbon olefins is the petroleum route. However, with the increasing shortage and heaviness of petroleum resources, the economical efficiency of the olefin production process of the petroleum route has been significantly reduced, and the low-carbon olefin production technology of the non-petroleum route has been greatly developed. The production of light olefins from methanol/dimethyl ether has achieved a production scale of one million tons. In the existing methanol-to-olefin process, circulating hydrocarbons are introduced into the methanol-to-olefin reactor as raw materials to participate in the reaction, and the circulating hydrocarbons contain cyclic hydrocarbons, which is not conducive to the generation of low-carbon olefins, and easily causes catalyst coking and deactivation.

SUMMARY OF THE INVENTION

In view of this, the present invention provides a method for producing low-carbon olefins and gasoline by utilizing Fischer-Tropsch synthetic oil, which can effectively couple the Fischer-Tropsch synthesis process and the methanol-to-olefins process, and The value-added C5/C6 fraction is applied to the methanol-to-olefin production process, and compared with the original methanol-to-olefin process in which all recycled hydrocarbons are recycled to the methanol-to-olefin reactor, the improved process of the present invention can significantly increase low carbon emissions. Olefin yield, increase the added value of the C5/C6 fraction in the Fischer-Tropsch synthesis process, and increase the revenue of the methanol-to-propylene process.

The present invention adopts following technical scheme to achieve its purpose:

The invention provides a method for producing low-carbon olefins by utilizing Fischer-Tropsch synthetic oil and producing gasoline. The C5/C6 fraction in the product obtained by the Fischer-Tropsch synthesis process is introduced into a methanol-to-olefins reactor of a methanol-to-olefins process as a raw material stream , producing light olefins and gasoline products by reacting in a methanol-to-olefins reactor; wherein the C5/C6 fractions introduced into the methanol-to-olefins reactor are used to replace part or all of the original process for introduction into methanol-to-olefins reactors. Recycle hydrocarbons in an olefin reactor; the light olefins include ethylene, propylene and/or butenes. Specifically, it includes the following steps:

1) the first stage: methanol enters the DME reactor to carry out the reaction of synthesizing dimethyl ether from methanol to obtain a first product stream, the first product stream comprising dimethyl ether, water and methanol;

2) The second stage: the first product stream enters the methanol-to-olefins reactor for reaction, and from the obtained product, recycle hydrocarbons, low-carbon olefins and gasoline products are separated and obtained, and the low-carbon olefins include ethylene, propylene and/or butylene. alkene;

Wherein, in the second stage, the C5/C6 fraction from the product obtained from the Fischer-Tropsch synthesis process and the recycle hydrocarbons obtained in the second stage are introduced into the methanol-to-olefins reactor as a feedstock stream to participate in the reaction; and, In the total amount of the C5/C6 fraction and the circulating hydrocarbons introduced into the methanol-to-olefins reactor, the C5/C6 fraction accounts for 10wt%-100wt% (for example, 10wt%, 20wt%, 30wt% %, 40wt%, 50wt%, 60wt%, 70wt%, 80wt%, 90wt%, 100wt%, etc.), more preferably the ratio is 50wt%-100wt% (eg 50wt%, 60wt%, 70wt%, 80wt%, 90wt% , 100wt%, etc.).

In a preferred embodiment of the present invention, the C5/C6 fraction includes the following components by mass percentage: 15%-70% (eg 15%, 25%, 35%, 45%, 55%, 65%, 70%, etc.) C5-C6 alkanes, 15%-70% (eg 15%, 25%, 35%, 45%, 55%, 65%, 70%, etc.) of C5-C6 alkenes and 1%-20% (1%, 5 %, 10%, 15%, 20%, etc.) of oxygen-containing compounds; wherein, the oxygen-containing compounds are mainly alcohols, preferably the oxygen-containing compounds contain more than 80% (for example, 80%, 90%, 95%, etc. ) alcohols in a mass proportion, the alcohols are preferably methanol and/or ethanol; the oxygen-containing compound may also contain a small amount of ketones, aldehydes, acids and other components.

In some specific embodiments, in the methanol-to-olefin reactor, the catalyst used is a molecular sieve catalyst; preferably, the catalyst is a commercially available Clariant HZSM-5 catalyst, and the catalyst model is MTPROP-1.

The present invention is a technical scheme formed by improving the existing methanol-to-olefin process. The improvement is mainly that: in the existing methanol-to-olefin process, all circulating hydrocarbons are recycled to the methanol-to-olefin reactor to participate in the reaction. And the present invention replaces part or all of the circulating hydrocarbon, and the replacement is the C5/C6 fraction in the product obtained from the Fischer-Tropsch synthesis process; the replacement ratio is controlled at 10wt%-100wt%.

As for the methanol-to-olefins process itself, it is well known to those skilled in the art. The process mainly includes two stages. The first stage is the reaction of methanol entering the DME reactor to synthesize dimethyl ether from methanol to obtain the first product stream, Mainly contains dimethyl ether, water, methanol, etc.; the second stage is to introduce the first product stream into the methanol-to-olefins reactor, contact with the catalyst in the reactor, and react to generate gaseous products containing low-carbon olefins (low-carbon olefins). ) and liquid product; the liquid product is separated and then obtains downstream products such as C5/C6 circulating hydrocarbons and gasoline products, and the specific separation process that separates and obtains circulating hydrocarbons and gasoline products from the liquid products is the prior art in the art, and will not be repeated. For example, as known to those skilled in the art, the C5/C6 circulating hydrocarbons can be obtained by separation in this way: the liquid product is fed into the debutanizer, and the bottom product obtained at the bottom of the debutanizer is fed into the dehexanizer, The C5/C6 circulating hydrocarbons are produced at the top of the dehexane tower, and the gasoline product is produced at the bottom of the dehexane tower; the details of separating the C5/C6 circulating hydrocarbons and the gasoline product from the liquid product of the methanol-to-olefin reactor The process operation is the prior art in the art, and is well known to those skilled in the art, and will not be repeated here. Among them, the recycled hydrocarbons (the components include C5-C6 n-isomeric olefins, n-isoparaffins and cyclic hydrocarbons) will be recycled to the methanol-to-olefins reactor of the second stage. For specific process operations, reference can be made to the existing processes in the art, which will not be described in detail.

The improvement point of the present invention mainly lies in the second stage, that is, the C5/C6 fraction in the product obtained by the Fischer-Tropsch synthesis process partially or completely replaces the circulating hydrocarbons originally used for recycling to the methanol-to-olefins reactor.

Preferably, in the step 2) of the method of the present invention, the total mass flow of the C5/C6 fraction and the recycled hydrocarbons introduced into the methanol-to-olefins reactor is about 60-60% of the mass flow of the first product stream. 80% (eg 60%, 70%, 80%, etc.), wherein the first product stream mass flow is also equivalent to the methanol mass flow entering the DME reactor in step 1).

In the present invention, the process of synthesizing dimethyl ether from methanol in the DME reactor in the first stage is a mature technology in the art, which is well known to those skilled in the art, and will not be repeated here.

In the present invention, in the second stage, preferably, in step 2), in the methanol-to-olefin reactor, the reaction temperature is controlled to be 350-550°C, and the reaction pressure is -0.1MPa to 0.3MPa.

Preferably, the methanol to olefin reactor is a fixed bed reactor.

The Fischer-Tropsch synthesis process is well known in the art. For example, patent documents CN 1511188, CN101297022B, CN104204141B, etc. all disclose methods for converting synthesis gas into hydrocarbons by Fischer-Tropsch synthesis. The Fischer-Tropsch synthesis process described in the present invention is not particularly limited, and may be a low-temperature Fischer-Tropsch synthesis process or a high-temperature Fischer-Tropsch synthesis process. The C5/C6 fractions of the present invention can be obtained from various specific Fischer-Tropsch synthesis processes in the art. In the literature "Indirect Coal Liquefaction Technology and Research Progress", the principle and typical process of indirect liquefaction of coal through synthesis gas to synthesize liquid fuel are introduced in detail. The article points out that the indirect coal liquefaction process can be divided into low temperature coal indirect liquefaction process and high temperature coal indirect liquefaction process according to the reaction temperature of Fischer-Tropsch synthesis. It is called high temperature coal indirect liquefaction process. The indirect liquefaction of low temperature coal adopts fixed bed or slurry bed reactor; the indirect liquefaction of high temperature coal adopts fluidized bed (circulating fluidized bed, fixed fluidized bed) reactor. In the present invention, the catalysts used in the Fischer-Tropsch synthesis process are not particularly limited, and any catalysts commonly used in the art can be used. It is preferably an iron-based or cobalt-based catalyst, more preferably an iron-based catalyst.

The technical scheme provided by the invention has the following beneficial effects:

The present invention couples the Fischer-Tropsch synthesis process and the methanol-to-olefin process, and the inventors of the present application find that the C5/C6 fraction (Fischer-Tropsch synthetic oil) of the low value-added product of the Fischer-Tropsch synthesis process is introduced into the methanol-to-olefin reaction of the methanol-to-olefin process In the reactor, it is used to partially or completely replace the circulating hydrocarbons used therein. On the one hand, the introduction of C5/C6 fractions can improve the yield of low-carbon olefins, and the yield can reach higher than 65%; on the other hand, it can also obtain an octane number greater than 92% gasoline product, and the economic benefit is improved; and the method also increases the added value of the C5/C6 fraction obtained by the Fischer-Tropsch synthesis process, and simultaneously improves the economic benefit of the methanol-to-olefin process.

Detailed ways

In order to better understand the technical solutions of the present invention, the content of the present invention is further described below with reference to the examples, but the content of the present invention is not limited to the following examples.

In the following examples or comparative examples, the method for producing low-carbon olefins and co-producing gasoline comprises the steps:

1) The first stage: 10g/hr of methanol enters the DME reactor for the reaction of methanol to synthesize dimethyl ether. The reaction temperature of the DME reactor is 280°C and the reaction pressure is 0.1MPa. The CNM-3 of Southwest Chemical Research and Design Institute is used. type catalyst, the loading amount is 5g; the first product stream is obtained through the reaction, and the first product stream includes dimethyl ether, water and methanol.

2) the second stage: the first product stream obtained above enters the methanol-to-olefins reactor to react, the catalyst used is the HZSM-5 catalyst of Clariant MTPROP-1 specification, the reaction temperature is 480 ° C, and the reaction pressure is 0.1MPa , the catalyst loading amount is 10g; light olefins and liquid products are separated from the reaction product; wherein, the liquid product enters the debutanizer, and the bottom product enters the dehexane tower, and the top of the dehexane tower produces C5/ C6 recycles hydrocarbons and produces gasoline products at the bottom of the tower.

Wherein, in the second stage, according to the specific situation of each embodiment or comparative example, the C5/C6 fraction in the C5/C6 circulating hydrocarbon and/or the product obtained from the Fischer-Tropsch synthesis process is introduced into the methanol-to-olefins reactor. C5/C6 fraction and recycle hydrocarbons introduced into the methanol-to-olefins reactor had a total mass flow of 7 g/hr.

Example 1

In the total amount of C5/C6 fractions and circulating hydrocarbons introduced into the MTO reactor, the proportion of high-temperature iron-based Fischer-Tropsch synthesis C5/C6 products (ie C5/C6 fractions, or Fischer-Tropsch synthetic oil) accounted for 10wt % (that is, the Fischer-Tropsch synthesis C5/C6 product substitution % in Table 2, the same applies to the following examples), and the typical components of Fischer-Tropsch synthetic oil are shown in 1# in Table 1. The outlet product of the methanol-to-olefin reactor was analyzed by on-line gas chromatography Agilent 7890A, and the test results are shown in Table 2.

Example 2

In the total amount of C5/C6 fraction and circulating hydrocarbons introduced into the MTO reactor, the proportion of low-temperature iron-based Fischer-Tropsch synthesis C5-C6 products (ie C5/C6 fraction, or Fischer-Tropsch synthetic oil) accounted for 10wt %, the typical components of Fischer-Tropsch synthetic oil are shown in 2# in Table 1. The outlet product of the methanol-to-olefin reactor was analyzed by on-line gas chromatography, and the test results are shown in Table 2.

Example 3

In the total amount of C5/C6 fraction and circulating hydrocarbons introduced into the MTO reactor, the proportion of high-temperature iron-based Fischer-Tropsch synthesis C5-C6 products (ie C5/C6 fraction, or Fischer-Tropsch synthetic oil) accounted for 20wt %, the typical components of Fischer-Tropsch synthetic oil are shown in 1# in Table 1. The outlet product of the methanol-to-olefin reactor was analyzed by on-line gas chromatography, and the test results are shown in Table 2.

Example 4

In the total amount of C5/C6 fractions and circulating hydrocarbons introduced into the MTO reactor, the proportion of low-temperature iron-based Fischer-Tropsch synthesis C5-C6 products (ie C5/C6 fractions, or Fischer-Tropsch synthetic oil) accounted for 30wt %, the typical components of Fischer-Tropsch synthetic oil are shown in 2# in Table 1. The outlet product of the methanol-to-olefin reactor was analyzed by on-line gas chromatography, and the test results are shown in Table 2.

Example 5

In the total amount of C5/C6 fractions and circulating hydrocarbons introduced into the MTO reactor, the proportion of high-temperature iron-based Fischer-Tropsch synthesis C5-C6 products (ie C5/C6 fractions, or Fischer-Tropsch synthetic oil) accounted for 30wt %, the typical components of Fischer-Tropsch synthetic oil are shown in 3# in Table 1. The outlet product of the methanol-to-olefin reactor was analyzed by on-line gas chromatography, and the test results are shown in Table 2.

Example 6

In the total amount of C5/C6 fractions and circulating hydrocarbons introduced into the MTO reactor, the proportion of high-temperature iron-based Fischer-Tropsch synthesis C5-C6 products (ie C5/C6 fractions, or Fischer-Tropsch synthetic oil) is 100 % (that is, without introducing circulating hydrocarbons), the typical components of Fischer-Tropsch synthetic oil are shown in 3# in Table 1. The outlet product of the methanol-to-olefin reactor was analyzed by on-line gas chromatography, and the test results are shown in Table 2.

Comparative Example 1

The Fischer-Tropsch synthesis C5/C6 product was not used to replace the circulating hydrocarbons of the original process (that is, the replacement amount was 0 wt%), that is, only the circulating hydrocarbons were introduced, and the remaining conditions were the same as those in Example 1. The outlet product of the methanol-to-olefin reactor was analyzed by on-line gas chromatography, and the test results are shown in Table 2.

Table 1 Fischer-Tropsch synthesis C5/C6 product composition

serial number 1# 2# 3# component Mass content % Mass content % Mass content % Pentane 2.98 24.01 11.22 Pentene 25.23 3.25 17.50 Hexane 12.81 45.21 24.05 Hexene 43.71 12.58 45.03 methanol 5.11 3.47 0.04 Ethanol 9.68 10.50 1.16

Table 2

Those skilled in the art will appreciate that some modifications or adaptations of the present invention may be made under the teachings of this specification. These modifications or adjustments should also be within the scope defined by the claims of the present invention.

Claims (10)

1. a kind of method using Fischer-Tropsch synthesis oil production low-carbon alkene co-production gasoline, which comprises the steps of:

1) first stage: methanol enters in DME reactor the reaction for carrying out methanol-fueled CLC dimethyl ether, obtains the first product stream；

2) second stage: first product stream, which enters in methanol to olefins reaction device, to react, isolated from products therefrom Recycle hydrocarbons, low-carbon alkene and gasoline products, the low-carbon alkene include ethylene, propylene and/or butylene；

Wherein, it in the second stage, is introduced into methanol to olefins reaction device in fischer-tropsch synthesis process products obtained therefrom Recycle hydrocarbons obtained in C5/C6 fraction and the second stage participate in reacting as raw material flow stock；And introduce the methanol alkene In the total amount of the C5/C6 fraction in hydrocarbon reactor and the recycle hydrocarbons, the C5/C6 fraction proportion is 10wt%- 100wt%.

2. the method according to claim 1, wherein introducing the C5/C6 of the methanol to olefins reaction device In the total amount of fraction and the recycle hydrocarbons, the C5/C6 fraction proportion is 50wt%-100wt%.

3. method according to claim 1 or 2, which is characterized in that the C5/C6 fraction includes following mass percent Ingredient: C5-C6 alkane, the C5-C6 alkene of 15%-70% and the oxygenatedchemicals of 1%-20% of 15%-70%；Wherein, institute Stating oxygenatedchemicals is mainly alcohols, and the preferably described oxygenatedchemicals contains the alcohols of 80% or more mass ratio, the alcohols Preferably methanol and/or ethyl alcohol.

4. method according to claim 1-3, which is characterized in that in the methanol to olefins reaction device, institute It is molecular sieve catalyst with catalyst；It is preferred that the catalyst is HZSM-5.

5. method according to claim 1-4, which is characterized in that the second stage, products therefrom include gas The product liquid is inputted debutanizing tower by state product low-carbon alkene and product liquid, and tower bottom products obtained therefrom inputs de- hexane Tower, obtains the recycle hydrocarbons in dehexanizer tower top, obtains the gasoline products in dehexanizer tower bottom.

6. method according to claim 1-5, which is characterized in that in the step 2), introduce the methanol system The C5/C6 fraction in olefin hydrocarbon reactor and the total mass flow rate of the recycle hydrocarbons are the first product stream mass flow 60-80%.

7. method according to claim 1-6, which is characterized in that in step 2), the methanol to olefins reaction In device, reaction temperature control is 350-550 DEG C, and reaction pressure is -0.1MPa to 0.3MPa.

8. method according to claim 1-7, which is characterized in that the methanol to olefins reaction device is fixed bed Reactor.

9. method according to claim 1-8, which is characterized in that the fischer-tropsch synthesis process is Low Temperature Fischer Tropsch conjunction At technique or high temperature fischer-tropsch synthesis technology.

10. -9 described in any item methods according to claim 1, which is characterized in that catalysis used in the fischer-tropsch synthesis process Agent is iron-based or cobalt-base catalyst, preferably ferrum-based catalyst.