CN101928600A - A method for producing diesel or diesel blending components - Google Patents

Abstract

A method for producing diesel oil or diesel blending components. Fischer-Tropsch synthetic oil is mixed with coal direct liquefaction oil to obtain mixed oil, and the mixed oil is fractionated after hydrofining and hydroisomerization cracking to obtain diesel product or diesel blending components. According to the method provided by the invention, the two kinds of coal-derived oils can be converted into clean diesel oil meeting the Euro IV standard or diesel blending components with high cetane number. Compared with the hydro-upgrading of direct liquefied oil from coal, the present invention has moderate reaction conditions and low device investment and operation costs.

Description

A method for producing diesel or diesel blending components

technical field

The present invention relates to a method for producing diesel or diesel blending components from oil produced from coal. More specifically, it is a method for producing diesel oil or diesel blending components from direct coal liquefied oil and coal indirect liquefied oil in the presence of hydrogen.

Background technique

The rapid development of my country's national economy has a strong demand for energy. Since my country became a net importer of oil in 1993, the gap between oil supply and demand has expanded year by year, and the dependence on foreign crude oil has increased year by year. In 2006, the foreign dependence of crude oil was 43%. It is more than 46% in 2020 and is expected to reach 60% in 2020. Fluctuations and changes in the international oil market will directly affect the security and stability of our country's economy and politics. Solving the supply and demand problem of liquid fuels by synthesizing liquid fuels through non-petroleum routes not only meets the national energy strategic security requirements, but also plays an important role in promoting the long-term stable and sustainable development of the national economy.

Among many alternative energy technologies, Fischer-Tropsch synthesis technology has become a hot spot in the technology development of various countries and major oil companies. The raw materials for Fischer-Tropsch synthesis come from a wide range of sources. Coal, natural gas, associated gas from oil fields, light hydrocarbons from refineries, and low-quality residual oil can all be used as raw materials for syngas production. Fischer-Tropsch synthesis reaction has two technical routes: high-temperature method and low-temperature method according to different target products. The high temperature method mainly produces gasoline and various high value-added chemicals, and the low temperature method mainly produces heavy hydrocarbons. The liquid fuel produced by Fischer-Tropsch synthesis technology has good combustion performance and low emission pollution, which is called clean energy. The indirect coal liquefaction technology has the advantages of strong raw material adaptability and good oil quality, and there are already successful examples of commercial operation in foreign countries: Sasol has three factories with an annual output of about 7.4 million tons of synthetic oil in South Africa; Shell has three factories in Malaysia It has a factory with an annual output of about 540,000 tons of synthetic oil products. Other petroleum companies, such as ExxonMobil, Chevron, Topsoe, IFP, etc., have vigorously researched and developed in the field of Fischer-Tropsch synthesis technology.

CN1780899A discloses a method for producing synthetic low-sulfur diesel fuel from low-temperature Fischer-Tropsch feedstock. In the method, diesel fuel is obtained by distilling Fischer-Tropsch synthetic oil fraction into diesel fraction, and mixing diesel fraction with petroleum-based diesel oil.

US6858127 discloses a process for producing middle distillates. The Fischer-Tropsch synthetic oil processed in the method contains at least 40% by weight of C30+ hydrocarbons, the raw material is subjected to hydroisomerization cracking reaction, the reaction product is fractionated to obtain middle distillate oil and hydrogenated tail oil, and the hydrogenated tail oil is processed Hydroisomerization cracking reaction.

US5378348 discloses a process for producing middle distillates from Fischer-Tropsch wax. In this method, the Fischer-Tropsch synthetic wax is divided into light and heavy fractions (the cut point is 260° C.), the heavy fraction is subjected to hydroisomerization treatment, and the light fraction is subjected to hydrotreatment and hydroisomerization. Wherein the isomerization catalyst is a noble metal catalyst.

US6787022 discloses a method for producing diesel from Fischer-Tropsch wax. The >149°C distillate of the Fischer-Tropsch synthesis product is used as the raw material. The raw material first undergoes isomerization reaction in the first reaction zone, and then the reaction product enters the second reaction zone for catalytic dewaxing reaction. The isomerization catalyst is a noble metal catalyst loaded on amorphous silica-alumina, and the dewaxing catalyst is a spherical catalyst compounded by the isomerization catalyst and the dewaxing catalyst.

As early as 1913, Germany had started research on the technology of direct coal liquefaction to produce liquid hydrocarbon products, and industrialized the technology of producing gasoline by direct liquefaction of lignite in 1927. Since the first world oil crisis occurred in 1973, the direct coal liquefaction technology has attracted the attention of developed countries, and many direct coal liquefaction processes have been developed successively.

CN1896181A discloses a method for producing high cetane number diesel oil by direct liquefaction of coal. Coal direct liquefied oil can produce diesel with a cetane number higher than 45 through hydrorefining and hydroupgrading.

The liquid hydrocarbons prepared by Fischer-Tropsch synthesis have the advantage of extremely low sulfur and nitrogen content, and the cetane number of diesel oil can reach more than 70-80, but its density is low, generally lower than 0.78g/cm ³ , and cannot be directly used as a vehicle. Diesel oil can only be used as a blending component. Coal direct liquefaction is another way of coal to oil, but the quality of direct coal liquefaction oil is very poor, the cetane number of diesel fraction is very low, generally lower than 30, it is difficult to produce high quality under conventional hydro-upgrading conditions diesel fuel.

Contents of the invention

The purpose of the present invention is to provide a method for producing diesel products or high cetane number diesel oil blending components from coal to oil production on the basis of the prior art.

Method provided by the invention comprises the following steps:

(1) mixing Fischer-Tropsch synthetic oil and coal direct liquefaction oil to obtain mixed oil;

(2) Mixed oil and hydrogen enter the hydrorefining reaction zone after being mixed, and contact with the hydrofinishing catalyst under hydrofinishing conditions to obtain hydrorefined oil; fractionate hydrorefined oil to obtain diesel fraction I and tail oil fraction Fractions including I;

(3) The tail oil fraction I enters the hydroisomerization cracking reaction zone, contacts with the hydroisomerization cracking catalyst under the hydroisomerization cracking condition, obtains the hydrocracking oil; fractionates the hydrocracking oil, obtains the diesel fraction II and tail oil fraction II;

(4) The tail oil fraction II obtained in step (3) is recycled back to the hydroisomerization cracking reaction zone to carry out the hydroisomerization cracking reaction;

(5) Mixing the diesel fraction I and the diesel fraction II to obtain a diesel product or a diesel blending component.

The mixing ratio of the Fischer-Tropsch synthetic oil and the direct coal liquefied oil is 5:95 (weight ratio) to 95:5 (weight ratio), and the preferred mixing ratio is 30:70 (weight ratio) to 70:30 (weight ratio) Compare).

Coal direct liquefaction oil is the product oil obtained by hydrogenation of coal and solvent under reaction conditions. The coal direct liquefaction reaction conditions are a reaction temperature of 250-550° C. and a hydrogen partial pressure of 15-40 MPa. The distillation range of the direct coal liquefaction oil described in the present invention is 50-500°C.

The Fischer-Tropsch synthetic oil is a low-temperature Fischer-Tropsch synthetic oil with a distillation range of 20-680°C. Low-temperature Fischer-Tropsch synthetic oil is a liquid hydrocarbon obtained by contacting hydrogen and carbon monoxide with a Fischer-Tropsch synthesis catalyst under low-temperature Fischer-Tropsch synthesis conditions. The low-temperature Fischer-Tropsch synthesis conditions are reaction temperature 160-250° C., pressure 1.5-4.0 MPa, space velocity 300-3000 h ^-1 , hydrogen/carbon monoxide molar ratio 1.5-2.5. The Fischer-Tropsch synthesis catalyst is a cobalt-based Fischer-Tropsch synthesis catalyst.

Most of the olefins, oxygen and gums are removed from the mixed oil in the hydrotreating reactor, and the polycyclic aromatic hydrocarbons are partially saturated. The hydrofining conditions are hydrogen partial pressure 2.0-15.0 MPa, reaction temperature 250-400°C, hydrogen-oil volume ratio 100-1000v/v, volume space velocity 0.5-10.0h ^-1 .

The hydrorefining catalyst is a metal-supported catalyst, the carrier is amorphous alumina, and the metal component is VIB or/and VIII group non-noble metal, wherein the VIB group metal is Mo or/and W, and the VIII group metal is Co or/and Ni.

The reactant stream in the hydrofining reaction zone is cooled and then separated from gas and liquid, the hydrogen-rich gas obtained from the separation can be recycled back to the reaction zone, and the liquid stream obtained from the separation enters the fractionation tower. The fractionation tower is cut to obtain naphtha fraction I, diesel fraction I and tail oil fraction I, wherein the cutting point between naphtha fraction I and diesel fraction I is 140°C to 180°C, and the cut point between diesel fraction I and tail oil fraction I is The cutting point between them is 300°C to 360°C.

The obtained tail oil fraction I enters the hydroisomerization cracking reaction zone to carry out the isomerization and/or cracking reaction of hydrocarbons. The hydroisomerization cracking conditions are hydrogen partial pressure 2.0-15.0MPa, reaction temperature 300-450°C, hydrogen-oil volume ratio 100-1500v/v, and volume space velocity 0.5-5.0h ^-1 .

The hydroisomerization cracking catalyst is an amorphous silica-alumina supported noble metal catalyst or a non-noble metal catalyst, and the metal component of the non-noble metal catalyst is a VIB or/and VIII group non-noble metal, wherein the VIB group metal is Mo or/and W , the Group VIII metal is Co or/and Ni; the metal component of the noble metal catalyst is Pt or/and Pd.

The reactant stream in the hydroisomerization cracking reaction zone is cooled and then subjected to gas-liquid separation, the separated hydrogen-rich gas can be recycled back to the reaction zone, and the separated liquid stream enters the fractionation tower. The fractionation tower is cut to obtain naphtha fraction II, diesel fraction II and tail oil fraction II, wherein the cutting point between naphtha fraction II and diesel fraction II is 140°C to 180°C, and the cut point between diesel fraction II and tail oil fraction II The cutting point between them is 310°C to 370°C.

Advantages of the present invention:

(1) Diesel oil obtained by upgrading Fischer-Tropsch synthetic oil has the characteristics of low density and high cetane number, the density is generally lower than 0.78g/cm ³ , and the cetane number can generally reach more than 75; Diesel oil has the characteristics of high density and low cetane number, the density is generally higher than 0.86g/cm ³ , and the cetane number is generally lower than 30. Neither of the modified diesel oils can be directly used as commercial diesel oil. With the method provided by the present invention, Fischer-Tropsch synthetic oil and coal direct liquefied oil are modified by mixing and hydrogenation, and the diesel fractions thereof can be directly used as commercial diesel oil.

(2) Compared with the hydro-upgrading of direct coal liquefied oil, the reaction conditions of mixed hydro-upgrading of Fischer-Tropsch synthetic oil and direct coal liquefied oil are milder, which reduces the operating cost of the unit.

Description of drawings

The accompanying drawing is a schematic flow chart of the method for producing diesel or diesel blending components provided by the present invention.

Detailed ways

The method provided by the present invention will be further described below in conjunction with the accompanying drawings, but the present invention is not limited thereto.

The schematic flow chart of the process principle of the present invention is shown in the accompanying drawings. The process is described as follows: the mixture stream 1 of mixed oil and hydrogen enters the hydrofinishing reactor A for reaction, and the effluent 2 of the hydrofinishing reactor A enters the hydrotreating fractionator B for fractionation and cutting into naphtha fraction 3 and diesel fraction 4 and the tail oil fraction 5; the tail oil fraction 5 is mixed with the unconverted tail oil fraction 10 from the fractionating tower D and enters the hydroisomerization cracking reactor C as stream 6, and is added at the inlet of the hydroisomerization cracking reactor Hydrogen 11 to adjust the hydrogen-to-oil ratio in the hydroisomerization cracking reaction zone. Hydrocracking and/or isomerization reactions occur under the action of a hydroisomerization cracking catalyst, and the reaction product, stream 7, enters the fractionating tower D and cuts to obtain a naphtha fraction 8, a diesel fraction 9 and a tail oil fraction 10, which are not converted The heavy fraction, that is, the tail oil fraction 10, is recycled to the hydroisomerization cracking reactor C to continue the reaction, and finally realize the full conversion of the heavy fraction.

The following examples will further illustrate the method provided by the present invention, but do not limit the present invention thereby.

The properties of Fischer-Tropsch synthetic oil and coal direct liquefaction oil used in the test are shown in Table 1, and the two are mixed according to a certain ratio to obtain a blended oil.

The trade name of the hydrofinishing catalyst used in the test is RTF-1, and the trade name of the hydroisomerization cracking catalyst is RCF-1. Both are produced by Changling Catalyst Factory of Sinopec Catalyst Branch.

A fixed-bed hydrogenation reactor is adopted and operated in double reactors, one of which is filled with hydrofining catalyst RTF-1, with a catalyst loading capacity of 100ml; the second is loaded with hydroisomerization cracking catalyst RCF-1, with a catalyst loading capacity of 60ml.

Example 1

Fischer-Tropsch synthetic oil and coal direct liquefied oil are mixed according to the ratio of 30:70 to obtain stock oil A, whose properties are shown in Table 2. According to the method provided by the present invention, the hydrotreating and upgrading of the mixed oil is carried out, and the feed amount of the mixed oil is 123g/h.

The operating conditions of the hydrofining reaction zone are: temperature 320°C, hydrogen partial pressure 6.4MPa, hydrogen-to-oil volume ratio 450.

The operating conditions of the hydroisomerization cracking reaction zone are: temperature 365°C, hydrogen partial pressure 6.4MPa, hydrogen to oil volume ratio 800.

The temperature range of fractionation tower B cutting distillate oil is: naphtha fraction I is <150°C, diesel fraction I is 150-340°C, tail oil fraction I is >340°C.

The temperature range of fractionation tower D cutting distillate oil is: naphtha fraction II is <150°C, diesel fraction II is 150-370°C, tail oil fraction II is >370°C.

Diesel oil fraction I and diesel oil fraction II of fractionation tower B and fractionation tower D were mixed to obtain diesel oil 1, the properties of which are shown in Table 3.

Example 2

Fischer-Tropsch synthetic oil and coal direct liquefied oil are mixed according to the ratio of 50:50 to obtain raw oil B, its properties are shown in Table 2, and the hydrotreating and upgrading of the mixed oil is carried out according to the method provided by the present invention, and the feed amount of the mixed oil is 138g/h.

The operating conditions of the hydrofining reaction zone are: temperature 315°C, hydrogen partial pressure 6.4MPa, hydrogen to oil volume ratio 400.

The operating conditions of the hydroisomerization cracking reaction zone are: temperature 365°C, hydrogen partial pressure 6.4MPa, hydrogen to oil volume ratio 800.

The temperature range of fractionation tower B cutting distillate oil is: naphtha fraction I is <150°C, diesel fraction I is 150-330°C, tail oil fraction I is >330°C.

The temperature range of fractionation tower D cutting distillate oil is: naphtha fraction II is <150°C, diesel fraction II is 150-370°C, tail oil fraction II is >370°C.

Diesel fraction I and diesel fraction II of fractionation tower B and fractionation tower D were mixed, and the properties of diesel oil 2 obtained are shown in Table 3.

Example 3

Fischer-Tropsch synthetic oil and coal direct liquefied oil are mixed according to the ratio of 80:20 to obtain raw material oil C, whose properties are shown in Table 2. According to the method provided by the present invention, the hydrotreating and upgrading of the mixed oil is carried out, and the feed amount of the mixed oil is 150g/h.

The operating conditions of the hydrofining reaction zone are: temperature 310°C, hydrogen partial pressure 6.0MPa, hydrogen-to-oil volume ratio 400.

The operating conditions of the hydroisomerization cracking reaction zone are: temperature 365°C, hydrogen partial pressure 6.0MPa, hydrogen to oil volume ratio 800.

The temperature range of fractionation tower B cutting distillate oil is: naphtha fraction I is <150°C, diesel fraction I is 150-320°C, tail oil fraction I is >320°C.

The temperature range of fractionation tower D cutting distillate oil is: naphtha fraction II is <150°C, diesel fraction II is 150-370°C, tail oil fraction II is >370°C.

Diesel fraction I and diesel fraction II of fractionation tower B and fractionation tower D were mixed, and the properties of diesel oil 3 obtained are shown in Table 3.

As can be seen from the data of Example 1 and Example 2 in Table 3, the diesel oil obtained by the method of the present invention meets the European IV vehicle diesel standard. As can be seen from the data in Example 3, when the Fischer-Tropsch synthetic oil mixing ratio in the raw material is high, the density of the product diesel oil is low, which cannot meet the European IV vehicle diesel standard, and the remaining indicators can reach the European IV vehicle diesel Standard, but the cetane number of the resulting diesel product is very high, which is a high-quality high-cetane number diesel blending component.

Table 1 Properties of Fischer-Tropsch synthetic oil and direct coal liquefaction oil

Fischer-Tropsch synthetic oil Coal direct liquefied oil Density (20℃), g/ ^cm3 0.7910 0.9869 Viscosity (20℃), mm ² /s / 42.21 Freezing point, ℃ / 12 Carbon residue, wt% / 13.2 Bromine value, gBr/100g 11.3 20.8  PAHs, % by weight 0 31.0 Sulfur content, μg/g <5 396 Oxygen content, wt% 1.01 1.29 Distillation range, ℃ 5% 101 248 50% 372 326 90% 555 420 95% 616 453

Table 2 Mixed oil properties

Mixed oil A Mixed oil B Mixed oil C Density (20℃), g/ ^cm3 0.9282 0.8890 0.8301 Carbon residue, wt% 9.36 6.82 2.70 Bromine value, gBr/100g 18.63 16.38 13.25

Oxygen content, wt% 1.21 1.15 1.07 Distillation range, ℃ 5% 195 169 135 50% 341 351 365 90% 480 489 516 95% 532 543 597

Table 3 Diesel properties

Claims (11)

1. method of producing diesel oil or diesel oil blending component comprises:

(1) mixes Fischer-Tropsch synthesis oil and coal direct liquefaction oil, obtain mixing oil;

(2) mixing oil and hydrogen enter the hydrofining reaction district after mixing, and contact with Hydrobon catalyst under the hydrofining condition, obtain hydrofined oil; The fractionation hydrofined oil obtains comprising the cut of diesel oil distillate I and tail oil cut I;

(3) tail oil cut I enters hydroisomerizing cracking reaction district, contacts with the hydroisomerizing cracking catalyst under the hydroisomerizing cracking conditions, obtains hydrocrackates; The fractionation hydrocrackates obtains comprising the cut of diesel oil distillate II and tail oil cut II;

(4) the tail oil cut II of step (3) gained loops back hydroisomerizing cracking reaction district and carries out the hydroisomerizing cracking reaction;

(5) Medium diesel oil cut I and diesel oil distillate II obtain diesel product or diesel oil blending component.

2. in accordance with the method for claim 1, the blending ratio that it is characterized in that described Fischer-Tropsch synthesis oil and coal direct liquefaction oil is 5: 95 (weight ratio)～95: 5 (weight ratio).

3. in accordance with the method for claim 1, the blending ratio that it is characterized in that described Fischer-Tropsch synthesis oil and coal direct liquefaction oil is 30: 70 (weight ratio)～70: 30 (weight ratio).

4. in accordance with the method for claim 1, the boiling range that it is characterized in that described coal direct liquefaction oil is 50～500 ℃.

5. in accordance with the method for claim 1, it is characterized in that Fischer-Tropsch synthesis oil is the low temperature Fischer-Tropsch synthesis oil, boiling range is 20～680 ℃.

6. in accordance with the method for claim 1, it is characterized in that described hydrofining condition is hydrogen dividing potential drop 2.0～15.0MPa, 250～400 ℃ of temperature of reaction, hydrogen to oil volume ratio 100～1000v/v, volume space velocity 0.5～10.0h ^-1

7. in accordance with the method for claim 1, it is characterized in that described hydroisomerizing cracking conditions is hydrogen dividing potential drop 2.0～15.0MPa, 300～450 ℃ of temperature of reaction, hydrogen to oil volume ratio 100～1500v/v, volume space velocity 0.5～5.0h ^-1

8. in accordance with the method for claim 1, it is characterized in that described Hydrobon catalyst is a kind of metal load type catalyst, carrier is unformed aluminum oxide, and metal component is that VIB is or/and VIII family base metal, wherein the group vib metal is Mo or/and W, and VIII family metal is that Co is or/and Ni.

9. in accordance with the method for claim 1, it is characterized in that noble metal catalyst or non-precious metal catalyst that described hydroisomerizing cracking catalyst is the amorphous silicon aluminium load, the metal component of non-precious metal catalyst is that VIB is or/and VIII family base metal, wherein the group vib metal is Mo or/and W, and VIII family metal is that Co is or/and Ni; The metal component of noble metal catalyst is that Pt is or/and Pd.

10. in accordance with the method for claim 1, it is characterized in that diesel oil distillate I and the cut point between the tail oil cut I in the described step (2) are 300 ℃～360 ℃.

11. in accordance with the method for claim 1, it is characterized in that diesel oil distillate II and the cut point between the tail oil cut II in the described step (3) are 310 ℃～370 ℃.

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