CN113025375B

CN113025375B - Method for starting up catalytic reforming of naphtha by direct coal liquefaction

Info

Publication number: CN113025375B
Application number: CN202110292737.5A
Authority: CN
Inventors: 齐振东; 李海华; 张�杰; 韩来喜
Original assignee: China Shenhua Coal to Liquid Chemical Co Ltd; Ordos Coal to Liquid Branch of China Shenhua Coal to Liquid Chemical Co Ltd
Current assignee: China Shenhua Coal to Liquid Chemical Co Ltd; Ordos Coal to Liquid Branch of China Shenhua Coal to Liquid Chemical Co Ltd
Priority date: 2021-03-18
Filing date: 2021-03-18
Publication date: 2023-05-02
Anticipated expiration: 2041-03-18
Also published as: CN113025375A

Abstract

The invention relates to the field of catalytic reforming, and discloses a method for starting up catalytic reforming of direct coal liquefaction naphtha, which comprises the following steps: under the nitrogen atmosphere and the start-up condition, directly liquefying naphtha from coal, and contacting the naphtha with a reforming catalyst to perform dehydrogenation reaction to obtain recycle hydrogen and effluent; and when the purity of the circulating hydrogen reaches a set value, carrying out catalytic reforming reaction on the direct coal liquefied naphtha and a reforming catalyst under the reforming condition in a hydrogen atmosphere. The method provided by the invention has the advantages of low production cost and high flexibility.

Description

Method for starting up catalytic reforming of naphtha by direct coal liquefaction

Technical Field

The invention relates to the field of catalytic reforming, in particular to a method for starting up catalytic reforming of naphtha by directly liquefying coal.

Background

Catalytic reforming is a process of producing high-octane gasoline components and aromatic hydrocarbons from naphtha fractions, while being rich in hydrogen. Although catalytic reforming is a hydrogen-rich process, hydrogen circulation is required, mainly because of the prevention of catalyst coking and deactivation. Therefore, in the initial stage of catalytic start-up, hydrogen is often required to be purchased externally to satisfy the conditions in the initial stage of catalytic reforming, but the hydrogen is purchased externally at a relatively high cost and has poor flexibility.

Therefore, in order to solve the problem of hydrogen shortage at the beginning of catalytic reforming operation, the invention provides a method for directly liquefying naphtha by coal, which can reduce the production cost and improve the flexibility.

Disclosure of Invention

The invention aims to solve the technical problem of hydrogen shortage at the beginning of catalytic reforming operation in the prior art, and provides a method for catalytic reforming of directly liquefying naphtha by coal, which has the advantages of low production cost and high flexibility.

In order to achieve the above object, the present invention provides a method for starting up catalytic reforming of direct coal liquefaction naphtha, the method comprising: under the nitrogen atmosphere and the start-up condition, directly liquefying naphtha from coal, and contacting the naphtha with a reforming catalyst to perform dehydrogenation reaction to obtain recycle hydrogen and effluent; and when the purity of the circulating hydrogen reaches a set value, carrying out catalytic reforming reaction on the direct coal liquefied naphtha and a reforming catalyst under the reforming condition in a hydrogen atmosphere.

Compared with the prior art, in the start-up stage of catalytic reforming, nitrogen is firstly used as circulating gas of catalytic reforming reaction, and along with the continuous progress of the start-up stage, the nitrogen is gradually converted by the hydrogen obtained by catalytic reforming until reaching the condition (reforming condition) of the start-up stable stage. In particular, through the technical scheme of the invention, the technical defect that the catalyst is easy to coke and lose activity when nitrogen is started under the common condition in the prior art is solved. In the preferred embodiment of the invention, a specific type of catalyst and a specific raw material are adopted, and under the combined action of a specific process and process parameters, the catalyst carbon deposition deactivation caused by nitrogen reaction can be avoided, and hydrogen generated in a nitrogen starting stage can be used as circulating hydrogen for direct coal liquefaction starting, so that the running time of a direct coal liquefaction coal hydrogen production device is effectively shortened, the cost is greatly saved, the whole energy consumption is reduced, and the flexibility is improved; in addition, the aromatic hydrocarbon obtained by catalytic reforming has equivalent conversion rate in the prior art.

Drawings

FIG. 1 is a schematic illustration of the flow of a catalytic reforming start-up process according to one embodiment of the present invention.

Description of the reference numerals

1. Naphtha feed pump 2, dewatering tank 3 and arsenic removal tank

4. Heat exchanger 5, four-in-one heating furnace 6 and first reactor

7. A second reactor 8, a third reactor 9 and a fourth reactor

10. High-pressure separator 11, stabilizer 12, and recycle hydrogen compressor

13. Hydrogen delivery supercharger

Detailed Description

The endpoints and any values of the ranges disclosed herein are not limited to the precise range or value, and are understood to encompass values approaching those ranges or values. For numerical ranges, one or more new numerical ranges may be found between the endpoints of each range, between the endpoint of each range and the individual point value, and between the individual point value, in combination with each other, and are to be considered as specifically disclosed herein.

The invention provides a method for starting up catalytic reforming of direct coal liquefaction naphtha, which comprises the following steps: under the nitrogen atmosphere and the start-up condition, directly liquefying naphtha from coal, and contacting the naphtha with a reforming catalyst to perform dehydrogenation reaction to obtain recycle hydrogen and effluent; and when the purity of the circulating hydrogen reaches a set value, carrying out catalytic reforming reaction on the direct coal liquefied naphtha and a reforming catalyst under the reforming condition in a hydrogen atmosphere.

According to some embodiments of the invention, the nitrogen atmosphere has a nitrogen purity of greater than 99% by volume, preferably greater than 99.5% by volume.

According to some embodiments of the invention, the start-up condition may include: the dehydrogenation reaction temperature is 300-500 ℃, preferably 400-450 ℃; the pressure of the dehydrogenation reaction is 0.4-1.2MPa, preferably 0.6-0.7MPa; the volume ratio of nitrogen to oil is (400-600): 1, preferably (450-550): 1.

in the invention, the preparation stage before starting can be carried out in a conventional manner in the art, for example, at the beginning of starting, the temperature and the pressure of the system are raised to meet the condition of dehydrogenation (starting condition), wherein the temperature raising rate is 10-50 ℃/h, preferably 20-40 ℃/h; the rate of pressure increase is 0.05-0.2MPa/h, preferably 0.1-0.15MPa/h.

In the present invention, it is preferable that the system temperature and pressure be raised to satisfy the conditions for dehydrogenation reaction in multiple stages.

According to some embodiments of the invention, preferably, the method may further comprise: injecting a chlorine injection agent into the dehydrogenation reaction while the coal direct liquefied naphtha is in contact with a reforming catalyst.

In the invention, in order to improve the octane number of the mixed aromatic hydrocarbon research method and not to cause the inactivation of the catalyst, the process of injecting the chlorine injection agent is preferably carried out in two stages; wherein the chlorine injection weight concentration of the first stage chlorine injection is 0.4-1.5ppm, preferably 0.8-1.2ppm; the chlorine injection weight concentration of the second stage chlorine injection is 0.4-1.5ppm, preferably 1-1.5ppm.

In the present invention, "ppm" refers to the concentration expressed as a percentage by mass of chlorine injection agent relative to the mass of the direct coal liquefaction naphtha, also referred to as the percentage by mass concentration.

According to some embodiments of the present invention, the chlorine injecting agent may be selected from at least one of tetrachloroethylene, dichloroethane (EDC), trichloroethane (methyl chloroform), and carbon tetrachloride, preferably tetrachloroethylene.

In the present invention, it is preferable that the analysis of the effluent of the dehydrogenation reaction is continued during the dehydrogenation reaction, and the concentration by weight of the injected chlorine is adjusted according to the analysis result.

In the present invention, preferably, the effluent refers to mixed aromatic hydrocarbons.

According to some embodiments of the invention, the reforming catalyst is a supported catalyst; the supported catalyst comprises a support selected from alumina and/or silica and an active component comprising Pt and Re.

According to some embodiments of the present invention, preferably, the Pt is present in an amount of 0.2 to 0.3 wt%, the Re is present in an amount of 0.2 to 0.3 wt%, and the support is present in an amount of 98 to 99.5 wt%, based on the total weight of the reforming catalyst;

more preferably, the Pt is present in an amount of 0.24 to 0.26 wt%, the Re is present in an amount of 0.23 to 0.27 wt% and the support is present in an amount of 98.8 to 99.3 wt%, based on the total weight of the reforming catalyst.

In the present invention, the reforming catalyst may be purchased from China petrochemical group, changling oil refining chemical industry, inc. (trade mark PRT-C or PRC-D).

In the present invention, it is preferable that the purity of the recycle hydrogen is increased as the dehydrogenation reaction proceeds until the start-up condition is changed to the reforming condition when a set value is reached. Wherein the transition from the start-up condition to the reforming condition may include an increasing system pressure and temperature (at 15-30 ℃/h) until the reforming condition is met.

According to some embodiments of the invention, the set point is a purity of hydrogen greater than 90% by volume, preferably greater than 95% by volume.

According to some embodiments of the invention, the reforming conditions include: the reforming temperature is 400-600 ℃, preferably 420-550 ℃; the reforming pressure is 0.5-1.5MPa, preferably 0.8-1.2MPa, and the hydrogen-oil volume ratio is (450-1000): 1, preferably (500-900): 1, a step of; the hydrogen partial pressure is 0.2-2MPa, preferably 0.5-1.6MPa; liquid hourly space velocity of 0.2-3h ^-1 Preferably 0.5-2h ^-1 。

According to some embodiments of the invention, the method may further comprise pre-treating the coal direct liquefaction naphtha prior to the dehydrogenation reaction;

wherein the preprocessing comprises: prefractionation, dehydration and dearsenification.

In the invention, preferably, the prefractionation is carried out to obtain the reaction feed naphtha with the distillation range of 105-185 ℃ so as to avoid exceeding the heavy benzene content of mixed aromatic hydrocarbon after reforming reaction.

In the present invention, preferably, the present invention, the dehydrating agent for dehydration can be a 5A (calcium) molecular sieve drying agent purchased from China petrochemical group Changling oil refining chemical industry Limited liability company; the dearsenifying agent for dearsenifying can be purchased from China petrochemical group dearsenifying agent (trademark SR-18) of the company responsible for refining chemical industry, inc. of Changling.

According to some embodiments of the invention, preferably, the coal direct liquefied naphtha meets the following requirements:

As＜2μg/kg，Pb＜20μg/kg，Cu＜50μg/kg，S＜3mg/kg，N＜1.5mg/kg，Cl＜2mg/kg，H ₂ O＜50mg/kg；

preferably, as < 1. Mu.g/kg, pb < 10. Mu.g/kg, cu < 10. Mu.g/kg, S < 0.5mg/kg, N < 0.5mg/kg, cl < 0.5mg/kg, H ₂ O＜20mg/kg。

In the present invention, preferably, the direct coal liquefaction naphtha further satisfies: the distillation range is 90-200deg.C, more preferably 105-180deg.C; density (at 20 ℃) of 0.5-1g/cm ³ More preferably 0.7-0.8g/cm ³ The method comprises the steps of carrying out a first treatment on the surface of the The aromatic hydrocarbon potential is 50 to 150 wt%, more preferably 65 to 100 wt%; the olefin content is less than 1mg/kg, more preferably less than 0.5mg/kg.

In the present invention, in the case where the raw materials (including naphtha and catalyst) do not satisfy the above-described requirements of the present invention, the technical object of the present invention cannot be achieved.

According to a preferred embodiment, the method comprises:

under the nitrogen atmosphere and the start-up condition, directly liquefying naphtha from coal, and contacting the naphtha with a reforming catalyst to perform dehydrogenation reaction to obtain recycle hydrogen and effluent; and when the purity of the circulating hydrogen reaches a set value, carrying out catalytic reforming reaction on the direct coal liquefied naphtha and a reforming catalyst under the reforming condition in a hydrogen atmosphere. Wherein the reforming catalyst is a supported catalyst; the supported catalyst comprises a carrier and an active component, wherein the carrier is selected from alumina and/or silicon oxide, and the active component comprises Pt and Re; the content of Pt is 0.24-0.26 wt%, the content of Re is 0.23-0.27 wt% and the content of carrier is 98.8-99.3 wt% based on the total weight of the reforming catalyst. The coal direct liquefaction naphtha meets the following requirements: as < 1. Mu.g/kg, pb < 10. Mu.g/kg, cu < 10. Mu.g/kg, S < 0.5mg/kg, N < 0.5mg/kg, cl < 0.5mg/kg, H ₂ O＜20mg/kg。

In the present invention, the direct coal to liquid naphtha catalytic reforming of the present invention may preferably be performed in an apparatus as shown in fig. 1:

pretreating direct coal liquefaction naphtha until the contact requirement with the reforming catalyst is met; under the nitrogen atmosphere, nitrogen in the reforming system is boosted, then the four-in-one heating furnace is ignited and heated to 200-300 ℃ at a certain heating rate, warm-up is carried out, and after the warm-up is finished, the temperature is continuously raised to 350-400 ℃; then controlling a certain nitrogen-oil volume ratio and system pressure, introducing pretreated naphtha and a reforming catalyst into a reactor, and continuously heating to the dehydrogenation reaction temperature for dehydrogenation reaction to obtain circulating hydrogen and effluent; chlorine injection is carried out while oil is fed; along with the progress of dehydrogenation reaction, when the purity of the circulating hydrogen reaches a set value, the system continuously rises to 400-600 ℃ at a certain temperature rising rate, the pressure in the system rises to 0.5-1.5MPa, and a certain hydrogen-oil ratio and liquid hourly space velocity are controlled to perform catalytic reforming reaction, so that a reformate is obtained.

The present invention will be described in detail by examples.

Example 1

Pretreating direct coal liquefaction naphtha until the contact requirement with the reforming catalyst is met; under the nitrogen atmosphere, nitrogen in the reforming system is boosted, then the four-in-one heating furnace is ignited and heated to the temperature of 250 ℃ at the inlet of the reactor at the heating rate of 30 ℃/h, warm-up is carried out, and after the warm-up is finished, the temperature is continuously raised to 370 ℃; the nitrogen oil volume ratio is controlled to be 400: 1. introducing pretreated naphtha and a reforming catalyst into a reactor at the pressure of 0.6MPa, continuously heating to 450 ℃ at the speed of 20 ℃/h, and carrying out dehydrogenation reaction to obtain circulating hydrogen and effluent; chlorine injection is carried out while oil is fed, the chlorine injection amount of the first section of chlorine injection is 1.2ppm, and the chlorine injection amount of the second section of chlorine injection is 1.4ppm; wherein the chlorine injection agent is tetrachloroethylene; along with the progress of dehydrogenation reaction, when the purity of the circulating hydrogen reaches 95% by volume, the system continuously rises to 500 ℃ at a heating rate of 20 ℃/h, the pressure in the system rises to 1.1MPa, and the hydrogen-oil volume ratio is controlled to be 600: 1. liquid hourly space velocity of 0.8h ^-1 And (3) carrying out catalytic reforming reaction at the hydrogen partial pressure of 1MPa to obtain a reformate.

In the obtained reformate, the research octane number of mixed aromatic hydrocarbon is 99, the aromatic hydrocarbon content is 75%, and the purity of hydrogen is 95%.

Example 2

Pretreating direct coal liquefaction naphtha until the contact requirement with the reforming catalyst is met; under the nitrogen atmosphere, nitrogen in the reforming system is boosted, then the four-in-one heating furnace is ignited and heated to the temperature of 250 ℃ at the inlet of the reactor at the heating rate of 30 ℃/h, warm-up is carried out, and after the warm-up is finished, the temperature is continuously raised to 370 ℃; the nitrogen oil volume ratio was then controlled to 500: 1. introducing pretreated naphtha and a reforming catalyst into a reactor, continuously heating to 400 ℃ at the speed of 20 ℃/h, and carrying out dehydrogenation reaction to obtain circulating hydrogen and effluent, wherein the pressure is 0.7MPa; chlorine injection is carried out while oil is fed, the weight concentration of chlorine injection of the first section of chlorine injection is 1ppm, and the weight concentration of chlorine injection of the second section of chlorine injection is 1.2ppm; wherein the adopted chlorine injection agent is tetrafluoroethylene; along with the progress of dehydrogenation reaction, when the purity of the circulating hydrogen reaches 95% by volume, the system continuously rises to 420 ℃ at a heating rate of 20 ℃/h, the pressure in the system rises to 1.2MPa, and the hydrogen-oil volume ratio is controlled to be 600 respectively: 1. liquid hourly space velocity of 1h ^-1 And (3) carrying out catalytic reforming reaction at the hydrogen partial pressure of 0.8MPa to obtain a reformate.

In the obtained reformate, the research octane number of mixed aromatic hydrocarbon is 97, the aromatic hydrocarbon content is 72 percent, and the purity of hydrogen is 95 percent.

Example 3

The procedure of example 1 was followed, except that the dehydrogenation reaction was carried out at 380℃at the start-up stage.

In the obtained reformate, the research octane number of mixed aromatic hydrocarbon is 92, the aromatic hydrocarbon content is 67, and the purity of hydrogen is 92%.

Example 4

The procedure of example 1 was followed except that the dehydrogenation reaction was carried out at the start-up stage at a pressure of 1.2MPa.

In the obtained reformate, the research octane number of mixed aromatic hydrocarbon is 95, the aromatic hydrocarbon content is 71, and the hydrogen purity is 94.

Example 5

The procedure of example 1 was followed except that a one-stage chlorine injection process was used instead of a two-stage chlorine injection process.

In the obtained reformate, the research octane number of mixed aromatic hydrocarbon is 88, the aromatic hydrocarbon content is 61, and the hydrogen purity is 89.

Example 6

The procedure of example 1 was followed except that the chlorine injection agent dichloroethane was replaced with tetrachloroethylene.

In the obtained reformate, the research octane number of mixed aromatic hydrocarbon is 95, the aromatic hydrocarbon content is 73, and the hydrogen purity is 93.

Comparative example 1

The dehydrogenation reaction was performed as in the examples except that the dehydrogenation reaction was performed under a hydrogen atmosphere and under start-up conditions.

In the obtained reformate, the research octane number of mixed aromatic hydrocarbon is 99, the aromatic hydrocarbon content is 75, and the hydrogen purity is 95.

The results show that the starting method (nitrogen starting) of the catalytic reforming of the direct coal liquefaction naphtha provided by the invention has basically the same properties as reformate obtained by hydrogen starting, but in the invention, the nitrogen starting greatly reduces the running cost of the device and the production is more flexible.

The preferred embodiments of the present invention have been described in detail above, but the present invention is not limited thereto. Within the scope of the technical idea of the invention, a number of simple variants of the technical solution of the invention are possible, including combinations of the individual technical features in any other suitable way, which simple variants and combinations should likewise be regarded as being disclosed by the invention, all falling within the scope of protection of the invention.

Claims

1. A method for starting up catalytic reforming of a direct coal liquefaction naphtha, the method comprising: under the nitrogen atmosphere and the start-up condition, directly liquefying naphtha from coal, and contacting the naphtha with a reforming catalyst to perform dehydrogenation reaction to obtain recycle hydrogen and effluent; when the purity of the circulating hydrogen reaches a set value, under the hydrogen atmosphere, directly liquefying coal to obtain naphtha, and carrying out catalytic reforming reaction on the naphtha and a reforming catalyst under a reforming condition;

wherein the reforming catalyst is a supported catalyst; the supported catalyst comprises a carrier and an active component, wherein the carrier is selected from alumina and/or silicon oxide, and the active component comprises Pt and Re;

wherein, based on the total weight of the reforming catalyst, the content of Pt is 0.2 to 0.3 weight percent, the content of Re is 0.2 to 0.3 weight percent, and the content of the carrier is 98 to 99.5 weight percent;

wherein, the start-up condition includes: the temperature of dehydrogenation reaction is 400-450 ℃; the pressure of the dehydrogenation reaction is 0.6-1.2MPa; the volume ratio of nitrogen to oil is (400-600): 1, a step of;

wherein a chlorine injection agent is injected into the dehydrogenation reaction while the direct coal liquefied naphtha is in contact with a reforming catalyst;

wherein the chlorine injection process is carried out in two stages; the chlorine injection weight concentration of the first stage chlorine injection is 0.4-1.2ppm relative to the direct coal liquefaction naphtha; the weight concentration of the injected chlorine in the second section is 0.4-1.4ppm;

the reaction device comprises a naphtha feed pump, a dehydration tank, an arsenic removal tank, a heat exchanger, a four-in-one heating furnace, a first reactor, a second reactor, a third reactor, a fourth reactor and a high-pressure separator which are connected in sequence;

wherein the first section chlorine injection position is between the arsenic removal tank and the heat exchanger; the second stage chlorine injection is positioned between the second reactor and the third reactor.

2. The method of claim 1, wherein the nitrogen atmosphere has a nitrogen purity of greater than 99% by volume.

3. The method of claim 2, wherein the nitrogen atmosphere has a nitrogen purity of greater than 99.5% by volume.

4. The method of claim 1, wherein the start-up condition comprises: the volume ratio of nitrogen to oil is (450-550): 1.

5. the method of claim 1, wherein the first stage injection of chlorine has an injection weight concentration of 0.8 to 1.2ppm relative to the coal direct liquefied naphtha; the weight concentration of the injected chlorine in the second section is 1-1.4ppm;

and/or the chlorine injection agent is at least one selected from tetrachloroethylene, dichloroethane, trichloroethane and carbon tetrachloride.

6. The method of claim 5, wherein the chlorine injecting agent is tetrachloroethylene.

7. The process of any of claims 1-6, wherein Pt is present in an amount of 0.24-0.26 wt%, re is present in an amount of 0.23-0.27 wt%, and the support is present in an amount of 98.8-99.3 wt%, based on the total weight of the reforming catalyst.

8. The method of any of claims 1-6, wherein the set point is a purity of greater than 90% by volume of hydrogen.

9. The method of claim 8, wherein the set point is a purity of greater than 95% by volume of hydrogen.

10. The method of any of claims 1-6, wherein the reforming conditions comprise: the reforming temperature is 400-600 ℃, the reforming pressure is 0.5-1.5MPa, and the hydrogen-oil volume ratio is (450-1000): 1, hydrogen partial pressure of 0.2-2MPa and liquid hourly space velocity of 0.2-3h ^-1 。

11. The method of claim 10, wherein the reforming conditions comprise: the reforming temperature is 420-550 ℃, the reforming pressure is 0.8-1.2MPa, and the hydrogen-oil volume ratio is (500-900): 1, hydrogen partial pressure of 0.5-1.6MPa, liquid hourly space velocity of 0.5-2h ^-1 。

12. The process of any of claims 1-6, further comprising pre-treating the coal direct liquefaction naphtha prior to the dehydrogenation reaction;

13. The method of any of claims 1-6, wherein the direct coal liquefaction naphtha meets the following requirements:

As＜2µg/kg，Pb＜20µg/kg，Cu＜50µg/kg，S＜3mg/kg，N＜1.5mg/kg，Cl＜2mg/kg，H ₂ O＜50mg/kg。

14. the method of claim 13, wherein the coal direct liquefied naphtha meets the following requirements:

As＜1µg/kg，Pb＜10µg/kg，Cu＜10µg/kg，S＜0.5mg/kg，N＜0.5mg/kg，Cl＜0.5mg/kg，H ₂ O＜20mg/kg。