Method and system for prolonging service life of fixed bed reactor and application

Abstract

The invention discloses a method and system for prolonging the service life of a fixed bed reactor and application, the method is carried out in one or more fixed bed reactors, the fixed bed reactors are connected in series and / or in parallel, the feeding and discharging position of at least one fixed bed reactor is switched in the reaction process, and the fixed bed reactors are connected in series and / or in parallel. And feeding from the original discharging position and discharging from the original feeding position. The method and the system can prolong the operation period of toluene disproportionation and alkylation transfer, heavy aromatics lightening or hydrodealkylation and other reactions, the reaction temperature is more stable under the condition of controlling the same total conversion rate, and the actual service life of the catalyst is prolonged.

Description

Technical Field

[0001] The invention belongs to the field of toluene disproportionation and alkylation, and in particular relates to a method, a system and an application for improving the service life of a fixed bed reactor. Background Art

[0002] The aromatics complex is the core unit for producing PX. It mainly uses straight-run naphtha as raw material to produce aromatic products such as benzene, paraxylene and o-xylene. It usually includes catalytic reforming, aromatics extraction, xylene separation, disproportionation and transalkylation, adsorption separation and xylene isomerization. In the traditional aromatics complex, the aromatic feedstock generated by reforming is split by a deheptanizer, and the top component is extracted to remove non-aromatics, and benzene or toluene is extracted. The bottom component is removed from the alkali tower by removing the olefin component, and then enters the xylene tower for separation. The C8A extracted from the top of the xylene tower enters the PX adsorption separation unit for separation. The C9(+) component is extracted from the bottom of the tower, and toluene and heavy aromatics (C9 + A) Transalkylation is an effective way to increase xylene production by using heavy aromatics, and is widely used. Since the reforming products contain a large amount of olefins, it is easy to form carbon deposits on the surface of the catalyst and adsorbent, resulting in the deactivation of the catalyst or adsorbent. Therefore, it is generally necessary to optimize the aromatic raw materials.

[0003] In the traditional aromatics complex, deolefination of reforming oil is an important step. The aromatic raw materials generated by reforming are divided into C7 - and C8 + Components, including C7 - After extraction to remove non-aromatic hydrocarbons, the trace olefins are removed through a bleaching clay tower. The benzene or toluene after olefin removal is used as the raw material for the transalkylation unit reaction. After the olefins are removed from the C8+ component through a bleaching clay tower, it enters a xylene tower for separation, and the C8A enters a PX adsorption separation unit for separation. The de-olefin process usually uses bleaching clay as an adsorbent. In the de-olefin process, bleaching clay is usually used as an adsorbent, and olefins undergo polymerization reactions on its surface and are adsorbed and removed. The disadvantage of bleaching clay adsorbent is that the service life is short and must be frequently replaced (cannot be regenerated). Abandoned bleaching clay will cause serious environmental pollution during the landfill process. The de-olefin catalyst uses a modified molecular sieve as an active component, and its life is significantly longer than that of bleaching clay, and it can be recycled, which can reduce the emission of waste solids to a certain extent. The olefin selective hydrogenation technology route can further improve the catalyst life, but the disadvantage is that it will cause a certain loss of aromatics.

[0004] US20080067053A1 discloses a method for producing xylene, which integrates a transalkylation reaction with a xylene isomerization reaction. The transalkylation reaction and the xylene isomerization reaction can be carried out in the same reaction zone, and the reaction product is separated into C6, C7 and C8 by a stabilization tower.+ A, C6 obtains pure benzene product through the benzene tower, C7 is used as the raw material for the alkyl transfer unit, C8+A is separated into xylene and heavy aromatics through the xylene tower and the heavy aromatics tower, and the heavy aromatics are returned to the alkyl transfer unit as raw materials. Xylene is separated by adsorption to obtain PX-depleted C8 aromatics and returned to the alkyl transfer unit.

[0005] CN1282733C discloses a catalyst for selective hydrogenation and deolefination of reforming oil, containing 0.1-1.0wt% of precious metal and 0.05-0.50wt% of alkali metal or alkaline earth metal as auxiliary agent. Under hydrogenation reaction conditions, reaction temperature is 150-250℃, pressure is 1.5-3.0MPa, volume space velocity is 2.0-4.0h -1 Under the above conditions, the bromine index of the product is less than 100mgBr / 100g oil, and the loss of aromatics is less than 0.5wt%. The above-mentioned deolefination catalyst is only for the removal of olefins from the C8 component, just to ensure that the bromine index of the PX adsorption separation feed is qualified. In order to extend its service life, the removal of olefins in components C9 and above and components C7 and below is often ignored, resulting in the subsequent entry of C9 heavy aromatics into the toluene disproportionation and alkyl transfer unit, causing the catalyst to accelerate carbon deposition and rapid decrease in activity.

[0006] In recent years, with the breakthrough of key issues such as large-scale crystallization separation equipment, PX crystallization separation technology has developed rapidly. Due to the advantages of low energy consumption, simple operation, and stable products, crystallization separation has been more and more widely used and is one of the development directions of PX separation technology in the future. Since PX crystallization separation technology does not involve the use of adsorbents, it has no strict restrictions on the olefin components in the raw materials. Therefore, it is not necessary to de-olefin the reformed oil in the process, which can greatly reduce waste solid emissions. However, the olefin content in the C9+A component that has not been de-olefinated is relatively high, which will accelerate the carbon deposition and deactivation of the catalyst and seriously affect the long-term operation of the process. The existing major disproportionation catalysts at home and abroad have restrictions on the olefin content in the raw materials and are not suitable for directly processing C9+A raw materials with a high bromine index. Summary of the invention

[0007] In order to overcome the problems existing in the prior art, the present invention provides a method and system for improving the life of a fixed bed reactor and its application, which can extend the operation cycle of reactions such as toluene disproportionation and alkylation transfer, heavy aromatics lightening or hydrodealkylation, etc., and the reaction temperature is more stable when the total conversion rate is controlled at the same level, or the conversion rate does not decrease significantly when the reaction temperature is controlled at the same level, thereby improving the actual service life of the catalyst. Among them, the improvement of the life of the fixed bed reactor can be to maintain the temperature of the fixed bed reactor at a gentle level or to extend the operation time of the fixed bed reactor.

[0008] The first aspect of the present invention is to provide a method for improving the service life of a fixed bed reactor, comprising: performing the reaction in one or more fixed bed reactors, wherein the plurality of fixed bed reactors are connected in series and / or in parallel, wherein during the reaction process, the feed and discharge positions of at least one of the fixed bed reactors are switched to feed from an original discharge position and discharge from an original feed position.

[0009] The feed material of the method contains olefins and / or naphthalene series. Preferably, based on 100 wt % of the feed material, the olefins and / or naphthalene series account for 0.01 to 15 wt %, preferably 0.3 to 10 wt %.

[0010] The method is carried out in one or more fixed bed reactors, and the inlet and outlet positions of at least one of the fixed bed reactors are switched according to the reaction time or according to the online detection of catalyst performance.

[0011] The method is carried out in one or more fixed bed reactors. The method is carried out in one or more fixed bed reactors and is switched according to the reaction time as follows: the entire reaction cycle is segmented, with 3000 to 8000 hours (preferably 4000 to 6000 hours) as a reaction section, and the time of the reaction section is 100%. When the reaction section is carried out to 30% to 70% (preferably 40% to 60%), the switching is carried out to switch the feed and discharge positions of at least one fixed bed reactor (preferably one, two or more).

[0012] The method is carried out in two fixed bed reactors connected in series, and is switched according to the reaction time as follows: when the reaction section is carried out to 30% to 70% (preferably 40% to 60%), the inlet and outlet positions of at least one of the fixed bed reactors are switched; preferably, the inlet and outlet positions of the fixed bed reactor logically first in the series are switched, or the inlet and outlet positions of the fixed bed reactor logically last in the series are switched, or the inlet and outlet positions of the fixed bed reactor logically first in the series are switched and the inlet and outlet positions of the fixed bed reactor logically last in the series are switched.

[0013] The method is carried out in m fixed bed reactors connected in series, m≥3 (preferably 3-10), and is switched according to the reaction time as follows: before the reaction stage reaches 30%-70% (preferably 40%-60%), the materials are contacted in sequence in the order of 1, 2, ..., m-1, m; when the reaction stage reaches 30%-70%, one, two or more of the inlet and outlet positions of the m fixed bed reactors are switched.

[0014] The method is carried out in one or more fixed bed reactors, and the switching is carried out according to the online detection of catalyst performance as follows: when the conversion rate is lower than 40-42%, the switching is carried out, and the feed and discharge positions of at least one of the fixed bed reactors are switched to feed from the original discharge position and discharge from the original feed position; or, when the same conversion rate is controlled to be maintained, when the reaction temperature is 5-20°C higher than the initial reaction temperature, the switching is carried out, and the feed and discharge positions of at least one of the fixed bed reactors are switched. Wherein, the online detection of catalyst performance refers to the online analysis of catalyst performance according to the product.

[0015] Preferably, the conversion rate of the catalyst is analyzed online while the reaction temperature is controlled unchanged, and the switching is performed when the conversion rate is lower than 40-42%; preferably, the switching is performed when the reaction temperature is 5-20°C higher than the initial reaction temperature while the conversion rate is controlled to maintain the same.

[0016] The conditions of the fixed bed reactor include: reaction pressure of 1.0-6.0 MPa, reaction temperature of 300-600°C, hydrogen-to-hydrocarbon molecular ratio of 0.5-20, liquid weight space velocity of 0.5-20h -1 .

[0017] The second aspect of the present invention is to provide a system for improving the service life of a fixed bed reactor, which is preferably used to carry out the method described in the first aspect of the present invention. The system comprises one or more fixed bed reactors and multiple pipelines, and each fixed bed reactor can switch the inlet and outlet positions between its top or bottom; preferably, the top and bottom of each fixed bed reactor are independently connected to the pipeline, and one or more valves are arranged on the pipeline for switching the inlet and outlet positions of the fixed bed reactor.

[0018] In one embodiment, the system includes a fixed bed reactor, a feed pipeline, a discharge pipeline, a connecting pipeline I, a connecting pipeline II, a connecting pipeline III and a connecting pipeline IV, wherein the connecting pipeline I and the connecting pipeline II are each independently connected to the feed pipeline and the discharge pipeline, one end of the connecting pipeline III is connected to the top of the fixed bed reactor, and the other end is connected to the connecting pipeline I, and one end of the connecting pipeline IV is connected to the bottom of the fixed bed reactor, and the other end is connected to the connecting pipeline II;

[0019] Preferably, a valve I is provided at the position where the connecting pipeline I, the connecting pipeline II and the feed pipeline are connected to each other, a valve II is provided at the position where the connecting pipeline I, the connecting pipeline II and the discharge pipeline are connected to each other, and a valve III is provided at the position where the connecting pipeline IV is connected to the connecting pipeline II.

[0020] In another embodiment, the system includes two fixed bed reactors, a feed pipeline 1, a discharge pipeline 2 and a connecting pipeline; preferably, the tops of the two fixed bed reactors are connected by a connecting pipeline i, and the bottoms of the two fixed bed reactors are connected by a connecting pipeline ii, and valve i, valve ii, valve iii, valve iv and valve v are sequentially arranged on the connecting pipeline i from left to right, and valve vi, valve vii, valve viii, valve viii, valve ix and valve x are sequentially arranged on the connecting pipeline ii from left to right;

[0021] Preferably, a connecting pipeline iii is provided between the feed pipeline 1 and the valve x, a connecting pipeline iv is provided between the feed pipeline 1 and the valve vi, the valve i, valve v, valve viii are connected to the discharge pipeline via connecting pipeline v, connecting pipeline vi, connecting pipeline vii, respectively, the valve ii is connected to the valve ix via connecting pipeline viiii, and the valve iv is connected to the valve vii via connecting pipeline ix.

[0022] More preferably, a valve xi is provided on the connecting pipeline iii, and the valve xi is connected to the valve iii via a connecting pipeline x.

[0023] The third aspect of the present invention is to provide the use of the method described in the first aspect of the present invention or the system described in the second aspect of the present invention in toluene disproportionation and alkylation transfer, heavy aromatics lightening or hydrodealkylation.

[0024] Compared with the prior art, the present invention has the following beneficial effects:

[0025] The method or system of the present invention is particularly suitable for toluene disproportionation and alkylation transfer, heavy aromatic lightening or hydrodealkylation containing olefins and / or naphthalene series in the feed raw materials;

[0026] The method or system of the present invention can extend the operating cycle of the reaction, make the reaction temperature more stable when the total conversion rate is the same, and increase the actual service life of the catalyst in the fixed bed reactor; or, extend the operating time when the reaction temperature is the same, and increase the actual service life of the catalyst in the fixed bed reactor. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 An embodiment of the system of the present invention is shown;

[0028] exist Figure 1 The reference numerals in the drawings are as follows: feed line 1, discharge line 2, connecting line I 3, connecting line II 4, connecting line III 5 and connecting line IV 6, valve I 7, valve II 8, valve III 9;

[0029] Figure 2 Another embodiment of the system of the present invention is shown;

[0030] exist Figure 2 The reference numerals in the drawings are as follows: connecting pipeline I 10', connecting pipeline ii 10", valve i 11, valve ii 12, valve iii 13, valve iv 14, valve v 15, valve vi 16, valve vii 17, valve viii 18, valve ix 19, valve x20, connecting pipeline iii 21, connecting pipeline iv 22, connecting pipeline v 23, connecting pipeline vi 24, connecting pipeline vii 25, connecting pipeline viii 26, connecting pipeline ix 27, valve xi 28, connecting pipeline x 29.

[0031] Figure 3a The operation modes of the embodiment 1 of the present invention before switching and the embodiment 2 after switching are shown;

[0032] Figure 3b The operation mode of the embodiment 1 of the present invention after switching and before switching of the embodiment 2 is shown;

[0033] Figure 3c , Figure 3d The operation modes of comparative examples 1 and 2 of the present invention are respectively shown;

[0034] Figure 4a , Figure 4b The operation modes of the embodiment 3 of the present invention before and after switching are shown;

[0035] Figure 5a , Figure 5b The operation modes of the fourth embodiment of the present invention before and after switching are shown;

[0036] Figure 5c The operation modes of Comparative Example 3 of the present invention are respectively shown;

[0037] Figure 6a , Figure 6b The operation modes of the embodiment 5 of the present invention before and after switching are shown;

[0038] Figure 7a , Figure 7b The operation modes of the sixth embodiment of the present invention before and after switching are shown;

[0039] Figure 7c The operation modes of Comparative Example 4 of the present invention are respectively shown;

[0040] Figure 8 A graph showing the relationship between reaction temperature, reaction time and conversion rate in Example 1 and Comparative Example 1;

[0041] Fig. 9A graph showing the relationship between reaction temperature, reaction time and conversion rate in Example 2 and Comparative Example 2;

[0042] Fig.10 A relationship diagram showing the reaction temperature, reaction time and conversion rate in Examples 3 to 4 and Comparative Example 3;

[0043] Fig.11 A graph showing the relationship between reaction temperature, reaction time and conversion rate in Examples 5 to 6 and Comparative Example 4;

[0044] Fig.12 A relationship diagram of reaction temperature, reaction time and conversion rate in Example 7 and Comparative Example 5 is shown. DETAILED DESCRIPTION

[0045] One of the objects of the present invention is to provide a method for improving the life of a fixed bed reactor, the method comprising: being carried out in one or more fixed bed reactors, the multiple fixed bed reactors being connected in series and / or in parallel, wherein during the reaction process, the feed and discharge positions of at least one of the fixed bed reactors are switched (in stages), and the feed and discharge positions are switched to the original feed and discharge positions, so as to maximize the use efficiency of the catalyst in each bed layer and improve the life of the fixed bed reactor (the catalyst inside).

[0046] The feeding and discharging positions are switched in stages by valve control. The fixed bed reactor may be an axial fixed bed reactor or a radial fixed bed reactor.

[0047] In a preferred embodiment, the method is carried out in one or more fixed bed reactors, and the feed and discharge positions of at least one of the fixed bed reactors are switched according to the reaction time or according to online detection of catalyst performance, and the feed and discharge positions are switched to the original feed and discharge positions.

[0048] The switching may be manual switching or automatic switching, preferably automatic online switching. The online detection is regular online detection, such as online detection once every 5 to 500 hours (e.g., 5 hours, 10 hours, 24 hours, 48 ​​hours, 72 hours, 96 hours, 120 hours, 150 hours, 168 hours, 200 hours, 240 hours, 300 hours, 360 hours, 400 hours, 450 hours or 480 hours).

[0049] Preferably, a material transport pipeline is arranged at the top or bottom of each fixed bed reactor, which can be used as a feed pipeline or a discharge pipeline, that is, the feed or discharge is preferably carried out at the top or bottom of the fixed bed reactor.

[0050] In a further preferred embodiment, the switching according to the reaction time is carried out as follows: the entire reaction cycle is segmented, with 3000-8000h (for example, any value of 3000h, 4000h, 5000h, 6000h, 7000h, 8000h or a range consisting of any two values) as a reaction section, and taking the time of the reaction section as 100%, when the reaction section has been carried out for 30%-70% (for example, any value of 30%, 40%, 50%, 60% or 70% or a range consisting of any two values), the switching is carried out to switch the feed and discharge positions of at least one fixed bed reactor.

[0051] Preferably, the switching according to the reaction time is performed as follows: the entire reaction cycle is segmented, with 4000 to 6000 hours as one reaction segment, and the time of the reaction segment is 100%. When the reaction segment has been completed for 40% to 60%, the switching is performed.

[0052] In another further preferred embodiment, the switching is performed according to the online detection of catalyst performance as follows: (preferably the conversion rate of the catalyst is analyzed online while the reaction temperature is controlled unchanged) when the conversion rate is lower than 40-42%, the switching is performed; or, when the same conversion rate is controlled to be maintained, the switching is performed when the reaction temperature is 5 to 20°C higher than the initial reaction temperature (preferably 5 to 10°C higher, for example 5°C, 6°C, 7°C, 8°C, 9°C or 10°C higher).

[0053] In a preferred embodiment, the feed material of the method contains olefins and / or naphthalene derivatives, wherein the olefins and / or naphthalene derivatives may form carbon deposits during long-term operation, thereby reducing the performance or life of the catalyst.

[0054] In a further preferred embodiment, based on 100wt% of the feed raw material, the olefins and / or naphthalene series are 0.01-15wt%, preferably 0.3-10wt%, for example, 0.01wt%, 0.05wt%, 0.1wt%, 0.5wt%, 1wt%, 2wt%, 4wt%, 6wt%, 8wt%, 10wt%, 12wt%, 14wt% or 15wt%.

[0055] In a preferred embodiment, the feed raw materials of the method include toluene, C9 + Aromatic hydrocarbons and impurities, wherein the impurities are olefins and / or naphthalene series.

[0056] Wherein, the naphthalene series is selected from naphthalene and its derivatives, and the olefin is selected from at least one of indene, propylene benzene and methyl propylene benzene.

[0057] In a further preferred embodiment, based on 100 wt% of the feed raw material, the content of toluene is 0 to 99.99 wt%, the content of C9+A aromatics is 0 to 99.99 wt%, and the content of impurities is 0.01 to 15 wt%.

[0058] For example, based on 100wt% of the feed raw material, the content of toluene is 0wt%, 10wt%, 20wt%, 30wt%, 40wt%, 50wt%, 60wt%, 70wt%, 80wt%, 90wt% or 99.99wt%, the content of C9+A aromatics is 0wt%, 10wt%, 20wt%, 30wt%, 40wt%, 50wt%, 60wt%, 70wt%, 80wt%, 90wt% or 99.99wt%, and the impurities are 0.01wt%, 0.05wt%, 0.1wt%, 0.5wt%, 1wt%, 2wt%, 4wt%, 6wt%, 8wt%, 10wt%, 12wt%, 14wt% or 15wt%.

[0059] In a further preferred embodiment, based on 100 wt% of the feed raw material, the content of toluene is 20-79.7 wt%, the content of C9+A aromatics is 20-79.7 wt%, and the content of impurities is 0.3-10 wt%.

[0060] In a preferred embodiment, when the feed raw material remains unchanged or changes during the entire reaction cycle, each fixed bed reactor is loaded with the same or different catalysts; preferably, when the feed raw material remains unchanged or changes during the entire reaction cycle, each fixed bed reactor is loaded with the same catalyst.

[0061] In a preferred embodiment, the method is carried out in one or more fixed bed reactors, and is switched according to the reaction time as follows: the entire reaction cycle is segmented, and when the reaction segment is carried out to 30% to 70% (preferably 40 to 60%), the feed and discharge positions of at least one fixed bed reactor are switched, that is, the feed is fed from the original discharge position and the discharge is discharged from the original feed position.

[0062] In a preferred embodiment, the method is carried out in a fixed bed reactor and is switched according to the reaction time as follows: the entire reaction cycle is segmented, and when the reaction segment is carried out to 30% to 70% (preferably 40% to 60%), the feed and discharge positions of the fixed bed reactor are switched.

[0063] In a preferred embodiment, the method is carried out in two fixed bed reactors connected in series, and the switching is carried out as follows according to the reaction time: the entire reaction cycle is segmented, and when the reaction stage is carried out to 30% to 70% (preferably 40% to 60%), the feed and discharge position of at least one of the fixed bed reactors is switched; preferably, the feed and discharge position of the (original) logically first fixed bed reactor in the series is switched, or the feed and discharge position of the (original) logically last fixed bed reactor in the series is switched, or the feed and discharge position of the logically first fixed bed reactor in the series is switched and the feed and discharge position of the logically last fixed bed reactor in the series is switched.

[0064] In a further preferred embodiment, the method is carried out in two fixed bed reactors connected in parallel, and the switching is carried out as follows according to the reaction time: the entire reaction cycle is segmented, and when the reaction stage is carried out to 30% to 70% (preferably 40% to 60%), the feed and discharge position of any one of the fixed bed reactors is switched or the feed and discharge positions of the two fixed bed reactors are switched.

[0065] In a preferred embodiment, the method is carried out in m series-connected fixed bed reactors, m≥3 (preferably 3-10, such as 3, 4, 5, 6, 7, 8, 9 or 10), and is switched according to the reaction time as follows: before the reaction stage reaches 30%-70% (preferably 40%-60%), the materials are contacted in the order of 1, 2, ..., m-1, m; when the reaction stage reaches 30%-70%, one, two or more inlet and outlet positions in the m fixed bed reactors are switched. .

[0066] In a preferred embodiment, the method is carried out in one or more fixed bed reactors, and the feed and discharge positions of at least one of the fixed bed reactors are switched according to the online detection of catalyst performance, and the feed and discharge are switched to the original feed position and the original feed position; wherein the online detection of catalyst performance refers to the online analysis of catalyst performance based on the product.

[0067] In a preferred embodiment, the method is carried out in one or more fixed bed reactors, and the switching is carried out according to the online detection of catalyst performance as follows: when the conversion rate is lower than 40-42%, the switching is carried out, and the feed and discharge positions of at least one of the fixed bed reactors are switched to feed from the original discharge position and discharge from the original feed position; or, when the same conversion rate is controlled to be maintained, when the reaction temperature is 5-20°C higher than the initial reaction temperature, the switching is carried out, and the feed and discharge positions of at least one of the fixed bed reactors are switched. Wherein, the online detection of catalyst performance refers to the online analysis of catalyst performance according to the product.

[0068] Preferably, the conversion rate of the catalyst is analyzed online while the reaction temperature is controlled unchanged, and the switching is performed when the conversion rate is lower than 40-42%; preferably, the switching is performed when the reaction temperature is 5-20°C higher than the initial reaction temperature while the conversion rate is controlled to maintain the same.

[0069] In a preferred embodiment, each fixed bed reactor is filled with a catalyst.

[0070] In a further preferred embodiment, the catalyst is selected from toluene disproportionation and transalkylation catalysts, heavy aromatics lightening catalysts or hydrodealkylation catalysts commonly used in the art.

[0071] In a preferred embodiment, the conditions of the method include: reaction pressure of 1.0-6.0 MPa, reaction temperature of 300-600°C, hydrogen-to-hydrocarbon molecular ratio of 1-20, liquid weight space velocity of 0.5-20 h -1 .

[0072] For example, the conditions of the method include: the reaction pressure is any value of 1.0MPa, 2.0MPa, 3.0MPa, 4.0MPa, 5.0MPa or 6.0MPa or a range consisting of any two values; the reaction temperature is any value of 300°C, 350°C, 400°C, 450°C, 500°C, 550°C or 600°C or a range consisting of any two values; the hydrogen-to-hydrocarbon molecular ratio is any value of 1, 2, 5, 8, 10, 12, 15, 18 or 20 or a range consisting of any two values; the liquid weight space velocity is 0.5h -1 , 1h -1 , 2h -1 , 5h -1 , 8h -1 , 10h -1 , 12h -1 , 15h -1 、18h -1 or 20h -1 Any value or range of any two values ​​in .

[0073] After a large number of experiments, the inventors found that if the method described in one of the purposes of the present invention is not used for switching, the reaction system will have a serious temperature rise problem during long-term operation. However, after switching using the method described in the present invention, the reaction system can maintain catalyst activity and a stable reaction temperature during long-term operation.

[0074] A second object of the present invention is to provide a system for increasing the life of a fixed bed reactor, comprising one or more fixed bed reactors and a plurality of pipelines, wherein the inlet and outlet positions of each fixed bed reactor can be switched between the top and the bottom thereof.

[0075] Wherein, the fixed bed reactor is an axial fixed bed reactor or a radial fixed length reactor. When the number of reactors is more than one, each reactor can be operated individually or simultaneously, and the feeding and discharging positions can be switched in stages through valve control to achieve different modes of series and parallel connection; the fixed bed reactor can be composed of one or more bed layers, and the catalyst type and catalyst storage can be determined according to the actual use conditions;

[0076] In a preferred embodiment, the top and bottom of each fixed bed reactor are independently connected to pipelines, and one or more valves are provided on the pipelines for switching the inlet and outlet positions of the fixed bed reactor.

[0077] In a preferred embodiment, (such as Figure 1 The system comprises a fixed bed reactor, a feed pipeline 1, a discharge pipeline 2, a connecting pipeline I 3, a connecting pipeline II 4, a connecting pipeline III 5 and a connecting pipeline IV 6, wherein the connecting pipeline I and the connecting pipeline II are each independently connected to the feed pipeline and the discharge pipeline, one end of the connecting pipeline III is connected to the top of the fixed bed reactor, and the other end is connected to the connecting pipeline I, and one end of the connecting pipeline IV is connected to the bottom of the fixed bed reactor, and the other end is connected to the connecting pipeline II.

[0078] In a further preferred embodiment, a valve I 7 (e.g., a three-way valve) is provided at the position where the connecting pipeline I 3, the connecting pipeline II 4, and the feed pipeline are connected to each other, a valve II 8 (e.g., a three-way valve) is provided at the position where the connecting pipeline I 3, the connecting pipeline II 4, and the discharge pipeline are connected to each other, and a valve III 9 (e.g., a three-way valve) is provided at the position where the connecting pipeline IV is connected to the connecting pipeline II.

[0079] In this way, by controlling valve I, valve II and valve III, it is possible to control whether the feed pipeline is connected to the top or the bottom of the fixed bed reactor, and it is possible to control whether the discharge pipeline is connected to the bottom or the top of the fixed bed reactor, thereby controlling the feed and discharge positions of the fixed bed reactor.

[0080] In a preferred embodiment, (such as Figure 2 The system as shown in FIG. 1 includes two fixed bed reactors, a feed line 1, a discharge line 2 and connecting lines.

[0081] In a further preferred embodiment, the tops of the two fixed bed reactors are connected by a connecting pipeline i 10', and the bottoms of the two fixed bed reactors are connected by a connecting pipeline ii 10", and valve i 11, valve ii 12, valve iii 13, valve iv 14 and valve v 15 are arranged in sequence from left to right on the connecting pipeline i 10', and valve vi 16, valve vii 17, valve viii 18, valve ix 19 and valve x 20 are arranged in sequence from left to right on the connecting pipeline ii10".

[0082] In a further preferred embodiment, a connecting pipeline iii 21 is provided between the feed pipeline 1 and the valve x 20, a connecting pipeline iv22 is provided between the feed pipeline 1 and the valve vi 16, the valve i 11, the valve v 15, and the valve vii 18 are connected to the discharge pipeline via connecting pipeline v 23, connecting pipeline vi 24, and connecting pipeline vii 25 respectively, the valve ii 12 is connected to the valve ix 19 via connecting pipeline viii 26, and the valve iv 14 is connected to the valve vii 17 via connecting pipeline ix 27.

[0083] In a further preferred embodiment, a valve xi 28 is provided on the connecting pipeline iii 21 , and the valve xi 28 is connected to the valve iii 13 via a connecting pipeline x 29 .

[0084] Among them, under such a setting, the feed pipeline can be controlled to be connected to the top of any fixed bed reactor, and the discharge pipeline can be controlled to be connected to the bottom of any fixed bed reactor, that is, the feed and discharge positions of any fixed bed reactor can be switched arbitrarily, and the two fixed bed reactors can be controlled to be connected in parallel or in series. That is, the feed and discharge positions can be switched in stages through valve control, and different modes of series and parallel connection can be realized.

[0085] The third object of the present invention is to provide an application of the method or system of the present invention in toluene disproportionation and alkylation transfer, heavy aromatics lightening or hydrodealkylation.

[0086] The endpoints and any values ​​of the scope disclosed in the present invention are not limited to the precise scope or value, and these scopes or values ​​should be understood to include values ​​close to these scopes or values. For numerical ranges, the endpoint values ​​of each scope, the endpoint values ​​of each scope and the individual point values, and the individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be regarded as specifically disclosed in this article. Hereinafter, in principle, each technical solution can be combined with each other to obtain a new technical solution, which should also be regarded as specifically disclosed in this article.

[0087] [Example and Comparative Example]

[0088] The present invention is described in detail below in conjunction with specific embodiments. It is necessary to point out that the following embodiments are only used to further illustrate the present invention and cannot be understood as limiting the scope of protection of the present invention. Some non-essential improvements and adjustments made to the present invention by those skilled in the art based on the contents of the present invention still fall within the scope of protection of the present invention.

[0089] It should also be noted that the various specific technical features described in the following specific embodiments can be combined in any suitable manner without contradiction. To avoid unnecessary repetition, the present invention will not further describe various possible combinations.

[0090] In addition, the various embodiments of the present invention may be arbitrarily combined as long as they do not violate the concept of the present invention. The technical solutions thus formed belong to part of the original disclosure of this specification and also fall within the protection scope of the present invention.

[0091] The raw materials used in the examples and comparative examples, unless otherwise specified, are disclosed in the prior art, for example, they can be directly purchased or prepared according to the preparation methods disclosed in the prior art.

[0092] The raw materials used in the embodiments and comparative examples include: 50wt% toluene + 50wt% C9 + A (based on the total weight of 50wt% toluene + 50wt% C9 + A as 100wt%, which includes 2wt% naphthalene and 0.03wt% olefins).

[0093] The fixed bed reactors of the examples and comparative examples are filled with a catalyst, which is the catalyst A1 in Example 1 of CN105272803A.

[0094] [Example 1]

[0095] Feed raw materials into the Figure 3a In the system with a single fixed bed reactor shown in FIG. 1 , the reaction cycle in Example 1 is 5000 h. With one reaction stage of 5000 h, the fixed bed reactor is fed from top to bottom. After running for 2500 hours (50% of the reaction stage), the fixed bed reactor is switched to Figure 3b The lower feed and upper discharge were operated for 2500 hours. The reaction pressure was controlled to be 3.0 MPa, the hydrogen-to-hydrocarbon molecular ratio was 3.0, and the liquid weight space velocity was 3.0 h -1 The reaction temperature, reaction time and conversion rate are as follows: Figure 8 shown.

[0096] [Comparative Example 1]

[0097] Feed raw materials into the Figure 3c The system with a single fixed bed reactor was operated for 5000 hours. The reaction pressure was controlled to be 3.0 MPa, the hydrogen-to-hydrocarbon molecular ratio was 3.0, and the liquid weight space velocity was 3.0 h -1 The reaction temperature, reaction time and conversion rate are as follows: Figure 8 shown.

[0098] Depend on Figure 8 It can be seen that under the same conditions of raw material composition, feed space velocity, reaction pressure, and hydrogen-to-hydrocarbon molecular ratio, the same total conversion rate is controlled. After switching the feed method, the reaction temperature increases more slowly than that of the comparative example, indicating that the catalyst life is extended.

[0099] [Example 2]

[0100] Feed raw materials into the Figure 3b In the system with a single fixed bed reactor, the reaction cycle in Example 2 is 5000 hours. With one reaction stage of 5000 hours, the fixed bed reactor is fed from bottom to top. After running for 2500 hours, Figure 3a The upper feed and lower discharge were operated for 2500 hours. The reaction pressure was controlled to be 2.5 MPa, the hydrogen-to-hydrocarbon molecular ratio was 3.2, and the liquid weight space velocity was 3.5 h -1 The reaction temperature, reaction time and conversion rate are as follows: Fig. 9 shown.

[0101] [Comparative Example 2]

[0102] Feed raw materials into the Figure 3d The system with a single fixed bed reactor was operated for 5000 hours. The reaction pressure was controlled to be 2.5 MPa, the hydrogen-to-hydrocarbon molecular ratio was 3.2, and the liquid weight space velocity was 3.5 h -1 The reaction temperature, reaction time and conversion rate are as follows: Fig. 9 shown.

[0103] Depend on Fig. 9 It can be seen that under the same conditions of raw material composition, feed space velocity, reaction pressure, and hydrogen-to-hydrocarbon molecular ratio, the same total conversion rate is controlled. After switching the feed method, the reaction temperature increases more slowly than that of the comparative example, indicating that the catalyst life is extended.

[0104] [Example 3]

[0105] Feed raw materials into the Figure 4a In the system with two fixed bed reactors shown in FIG. 1 , the reaction cycle in Example 3 is 5000 h. With one reaction period of 5000 h, each fixed bed reactor is fed from top to bottom. After 2500 hours of operation, Figure 4bThe second fixed bed reactor was switched to bottom feed and top discharge and continued to operate for 2500 hours. The reaction pressure was controlled to be 3.5 MPa, the hydrogen-to-hydrocarbon molecular ratio was 2.5, and the liquid weight space velocity was 3.0 h -1 The reaction temperature, reaction time and conversion rate are as follows: Fig.10 shown.

[0106] [Example 4]

[0107] Feed raw materials into the Figure 5a In the system with two fixed bed reactors shown in the figure, the reaction cycle in Example 4 is 5000 hours. With the 5000-hour reaction period, the first fixed bed reactor is fed at the bottom and discharged at the top, and the last fixed bed reactor is fed at the top and discharged at the bottom. After 2500 hours of operation, Figure 5b At the end of the switching logic shown, the fixed bed reactor continued to operate for 2500 hours with feeding from the bottom and discharging from the top. The reaction pressure was controlled to be 3.5 MPa, the hydrogen-to-hydrocarbon molecular ratio was 2.5, and the liquid weight space velocity was 3.0 h -1 The reaction temperature, reaction time and conversion rate are as follows: Fig.10 shown.

[0108] [Comparative Example 3]

[0109] Feed raw materials into the Figure 5c In the system with two fixed bed reactors shown in the figure, both fixed bed reactors were operated for 5000 hours with upper feeding and lower discharging. The reaction pressure was controlled to be 3.5 MPa, the hydrogen-to-hydrocarbon molecular ratio was 2.5, and the liquid weight space velocity was 3.0 h -1 The reaction temperature, reaction time and conversion rate are as follows: Fig.10 shown.

[0110] Depend on Fig.10 It can be seen that under the same conditions of raw material composition, feed space velocity, reaction pressure, and hydrogen-to-hydrocarbon molecular ratio, the same total conversion rate is controlled. After switching the feed method, the reaction temperature increases more slowly than that of the comparative example, indicating that the catalyst life is extended.

[0111] [Example 5]

[0112] Feed raw materials into the Figure 6a In the system with two fixed bed reactors shown in FIG. 1 , the reaction cycle in Example 5 is 5000 h. With one reaction period of 5000 h, each fixed bed reactor is fed from bottom to top. After 2500 hours of operation, Figure 6b At the end of the switching logic shown, the fixed bed reactor continued to operate for 2500 hours with upper feeding and lower discharging. The reaction pressure was controlled to be 3.5 MPa, the hydrogen-to-hydrocarbon molecular ratio was 2.5, and the liquid weight space velocity was 3.0 h -1 The reaction temperature, reaction time and conversion rate are as follows: Fig.11shown.

[0113] [Example 6]

[0114] Feed raw materials into the Figure 7a In the system with two fixed bed reactors shown in FIG. 1 , the reaction cycle in Example 6 is 5000 h. With one reaction period of 5000 h, each fixed bed reactor is fed from top to bottom. After 2500 hours of operation, Figure 7b At the end of the switching logic shown, the fixed bed reactor continued to operate for 2500 hours with feeding from the bottom and discharging from the top. The reaction pressure was controlled to be 3.5 MPa, the hydrogen-to-hydrocarbon molecular ratio was 2.5, and the liquid weight space velocity was 3.0 h -1 The reaction temperature, reaction time and conversion rate are as follows: Fig.11 shown.

[0115] [Comparative Example 4]

[0116] Feed raw materials into the Figure 7c In the system with two fixed bed reactors shown in the figure, both fixed bed reactors were operated for 5000 hours with upper feeding and lower discharging. The reaction pressure was controlled to be 3.5 MPa, the hydrogen-to-hydrocarbon molecular ratio was 2.5, and the liquid weight space velocity was 3.0 h -1 The reaction temperature, reaction time and conversion rate are as follows: Fig.11 shown.

[0117] Depend on Fig.11 It can be seen that under the same conditions of raw material composition, feed space velocity, reaction pressure, and hydrogen-to-hydrocarbon molecular ratio, the same total conversion rate is controlled. After switching the feed method, the reaction temperature increases more slowly than that of the comparative example, indicating that the catalyst life is extended.

[0118] [Example 7]

[0119] Feed raw materials into the Figure 2 In the system shown, the catalyst performance is switched according to online detection. When the conversion rate is lower than 42%, the feed and discharge positions are switched in time and the operation continues. The reaction pressure is controlled to be 3.0 MPa, the hydrogen-to-hydrocarbon molecular ratio is 3.0, and the liquid weight space velocity is 2.5 h -1 The reaction temperature, reaction time and conversion rate are as follows: Fig.12 shown.

[0120] use Figure 2 In the system shown, the reactor on the left is numbered A, the reactor on the right is numbered B, the upper end of reactor A is numbered A1, and the lower end of reactor A is numbered A2; the upper end of reactor B is numbered B1, and the lower end of reactor B is numbered B2. The specific feeding method and switching method are shown in the following table:

[0121]

[0122]

[0123] Taking "reaction feed-A1-A2-B1-B2-product discharge" as an example, it means that the feed is fed from the upper end A1 of reactor A and the discharge is from the lower end A2 of reactor A, and the material from the lower end of reactor A is fed from the upper end B1 of reactor B and the discharge is from the lower end B2 of reactor B.

[0124] The initial feed is carried out according to mode 1; when the operation is around 1800h, the conversion rate drops to 42%, and the conversion rate is switched to mode 2 at this time, and the conversion rate is improved; when the operation is around 3000h, the conversion rate drops to 42%, and the conversion rate is switched to mode 3 at this time, and the conversion rate is improved; when the operation is around 5800h, the conversion rate drops to 42%, and the conversion rate is switched to mode 4 at this time, and the conversion rate is improved; when the operation is around 7200h, the conversion rate drops to 42%, and the conversion rate is switched to mode 5 at this time, and the conversion rate is improved; when the operation is around 9500h, the conversion rate drops to 42%, and the conversion rate is switched to mode 6 at this time, and the conversion rate is improved; when the operation is around 11000h, the conversion rate drops to 42%, and the conversion rate is switched to mode 7 at this time, and the conversion rate is improved; when the operation is around 12500h, the conversion rate drops to nearly 42%, and the conversion rate is switched to mode 8 at this time. It can be seen from this embodiment that the method and system of the present invention can be operated for a long period of time and achieve unexpected technical effects.

[0125] [Comparative Example 5]

[0126] use Figure 2 The system shown in the figure was initially fed according to Mode 1 in Example 7, and the feed and discharge positions were not switched. It was found that the conversion rate kept decreasing. After 5000 hours of operation, the conversion rate had dropped below 40%. There was no need to continue the operation, and long-term operation was not possible. The reaction pressure was controlled to be 3.0 MPa, the hydrogen-to-hydrocarbon molecular ratio was 3.0, and the liquid weight space velocity was 2.5 h -1 The reaction temperature, reaction time and conversion rate are as follows: Fig.12 shown.

[0127] Depend on Fig.12 It can be seen that, under the conditions of the same raw material composition, feed space velocity, reaction pressure, and hydrogen-to-hydrocarbon molecular ratio, Example 7 and Comparative Example 5 control the same reaction temperature. After switching the feed method, the conversion rate of Example 7 is improved, while the conversion rate of Comparative Example 5 continues to decrease.

[0128] The present invention has been described in detail above in conjunction with specific implementations and exemplary examples, but these descriptions cannot be understood as limiting the present invention. Those skilled in the art understand that, without departing from the spirit and scope of the present invention, a variety of equivalent substitutions, modifications or improvements may be made to the technical solution of the present invention and its implementation methods, all of which fall within the scope of the present invention. The scope of protection of the present invention shall be subject to the attached claims.

Claims

1. A method for increasing the life of a fixed bed reactor, comprising: The reaction is carried out in one or more fixed bed reactors, wherein the multiple fixed bed reactors are connected in series and / or in parallel, wherein the feed and discharge positions of at least one of the fixed bed reactors are switched during the reaction process, and the feed and discharge positions are switched to the original feed and discharge positions.

2. The method according to claim 1, characterized in that: The feed material of the method contains olefins and / or naphthalene series. Preferably, based on 100 wt % of the feed material, the olefins and / or naphthalene series account for 0.01 to 15 wt %, preferably 0.3 to 10 wt %.

3. The method according to claim 1, characterized in that The method is carried out in one or more fixed bed reactors, and the inlet and outlet positions of at least one of the fixed bed reactors are switched according to the reaction time or according to the online detection of catalyst performance.

4. The method according to claim 3, characterized in that The method is carried out in one or more fixed bed reactors, and is switched according to the reaction time as follows: the entire reaction cycle is segmented, with 3000 to 8000 hours (preferably 4000 to 6000 hours) as a reaction section, and the time of the reaction section is 100%. When the reaction section has been completed for 30% to 70% (preferably 40% to 60%), the switching is carried out to switch the feed and discharge positions of at least one fixed bed reactor.

5. The method according to claim 3, characterized in that: The method is carried out in one or more fixed bed reactors, and switching is performed as follows according to online detection of catalyst performance: when the conversion rate is lower than 40-42%, the switching is performed to switch the feed and discharge positions of at least one of the fixed bed reactors.

6. The method according to claim 3, characterized in that The switching is performed according to the online detection of catalyst performance as follows: while controlling to maintain the same conversion rate, the switching is performed when the reaction temperature is 5 to 20° C. higher than the initial reaction temperature, and the feed and discharge positions of at least one of the fixed bed reactors are switched.

7. The method according to any one of claims 1 to 6, characterized in that: The conditions of the fixed bed reactor include: reaction pressure of 1.0-6.0 MPa, reaction temperature of 300-600°C, hydrogen-to-hydrocarbon molecular ratio of 0.5-20, liquid weight space velocity of 0.5-20h -1 .

8. A system for improving the life of a fixed bed reactor, preferably used for carrying out the method according to any one of claims 1 to 7, the system comprising one or more fixed bed reactors and a plurality of pipelines, each fixed bed reactor being capable of switching the inlet and outlet positions between the top and the bottom thereof; preferably, the top and the bottom of each fixed bed reactor are independently connected to the pipeline, and one or more valves are provided on the pipeline for switching the inlet and outlet positions of the fixed bed reactor.

9. The system according to claim 8, characterized in that The system comprises a fixed bed reactor, a feed pipeline, a discharge pipeline, a connecting pipeline I, a connecting pipeline II, a connecting pipeline III and a connecting pipeline IV, wherein the connecting pipeline I and the connecting pipeline II are independently connected to the feed pipeline and the discharge pipeline, one end of the connecting pipeline III is connected to the top of the fixed bed reactor, and the other end is connected to the connecting pipeline I, and one end of the connecting pipeline IV is connected to the bottom of the fixed bed reactor, and the other end is connected to the connecting pipeline II; Preferably, a valve I is provided at the position where the connecting pipeline I, the connecting pipeline II and the feed pipeline are connected to each other, a valve II is provided at the position where the connecting pipeline I, the connecting pipeline II and the discharge pipeline are connected to each other, and a valve III is provided at the position where the connecting pipeline IV is connected to the connecting pipeline II.

10. The system according to claim 8, characterized in that The system comprises two fixed bed reactors, a feed pipeline 1, a discharge pipeline 2 and a connecting pipeline; preferably, the tops of the two fixed bed reactors are connected by a connecting pipeline i, and the bottoms of the two fixed bed reactors are connected by a connecting pipeline ii, and valve i, valve ii, valve iii, valve iv and valve v are sequentially arranged on the connecting pipeline i from left to right, and valve vi, valve vii, valve viii, valve ix and valve x are sequentially arranged on the connecting pipeline ii from left to right; Preferably, a connecting pipeline iii is provided between the feed pipeline 1 and the valve x, a connecting pipeline iv is provided between the feed pipeline 1 and the valve vi, the valve i, the valve v, and the valve viii are connected to the discharge pipeline through the connecting pipeline v, the connecting pipeline vi, and the connecting pipeline vii respectively, the valve ii is connected to the valve ix through the connecting pipeline viiii, and the valve iv is connected to the valve vii through the connecting pipeline ix; More preferably, a valve xi is provided on the connecting pipeline iii, and the valve xi is connected to the valve iii via a connecting pipeline x.

11. Use of the method according to any one of claims 1 to 7 or the system according to any one of claims 8 to 10 in toluene disproportionation and alkylation transfer, heavy aromatic hydrocarbon lightening or hydrodealkylation, and is particularly suitable for toluene disproportionation and alkylation transfer, heavy aromatic hydrocarbon lightening or hydrodealkylation containing olefins and / or naphthalene series in the feed raw materials.

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