A method for hydroconversion of light naphtha
By using ZSM-5 molecular sieves and mordenite catalyst in a graded manner, isoalkanes in light naphtha are converted into n-alkanes, solving the problem of low quality of ethylene feedstock in existing technologies and achieving efficient ethylene production.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- CHINA PETROLEUM & CHEMICAL CORP
- Filing Date
- 2024-12-05
- Publication Date
- 2026-06-05
Smart Images
Figure CN122146338A_ABST
Abstract
Description
Technical Field
[0001] This invention belongs to the field of hydrocarbon oil hydroconversion, specifically relating to a hydroconversion method for producing high-quality ethylene feedstock from light naphtha. Background Technology
[0002] Petroleum fractions mainly consist of alkanes, cycloalkanes, and aromatics, with alkanes further divided into n-alkanes and isoalkanes. Among these different molecular compositions, alkanes are the best feedstocks for ethylene, especially n-alkanes, which consistently yield high yields of ethylene and trienes when used as ethylene feedstocks. However, as the molecular weight of isoalkanes decreases, their yields of ethylene and trienes gradually decline when used as ethylene feedstocks. Therefore, converting small-molecule isoalkanes into n-alkanes is a pressing issue that needs to be addressed in petroleum processing.
[0003] CN115612524A discloses a method for increasing the concentration of n-chain alkanes in a light naphtha feed stream. The method includes separating the naphtha feed stream into a stream rich in n-chain alkanes and a stream rich in non-n-chain alkanes. An isomerization feed stream is obtained from the non-n-chain alkanes stream and isomerized on an isomerization catalyst to convert the non-n-chain alkanes into n-chain alkanes and generate an isomerized effluent. Optionally, the isomerized effluent can be separated into a propane stream and a C4 stream in a single column. + Hydrocarbon feedstock. C4 + The hydrocarbon feed stream can be recycled to the step of separating the naphtha feed stream.
[0004] CN116023214A discloses a method and system for producing n-alkanes. The method involves contacting isobutane feedstock with an isobutane conversion catalyst in an isobutane conversion unit to carry out an isobutane conversion reaction. The isobutane conversion catalyst has high catalytic activity, is chlorine-free, safe and non-toxic, and reduces corrosion and wear on equipment. The resulting reaction product containing n-alkanes is introduced into a membrane separation unit for membrane separation treatment. The membrane separation element, including a molecular sieve membrane, enables efficient separation of n-alkanes and isoalkanes. The separation efficiency is high and the method is simple and easy to implement.
[0005] The above methods can all convert small molecule isoalkanes into n-alkanes, but the energy required for the conversion of hydrocarbons with different molecular structures is different, and it is difficult to effectively guarantee the yield of the target product by using a single conversion process. Summary of the Invention
[0006] To address the problems existing in the prior art, the purpose of this invention is to provide a method for the hydrogenation conversion of light naphtha. This method uses light naphtha as raw material and can effectively convert isoparaffins in light naphtha into n-paraffins, thereby improving the quality of ethylene feedstock.
[0007] This invention provides a method for the hydroconversion of light naphtha, the method comprising:
[0008] (1) Light naphtha, optionally added olefins, and hydrogen are mixed and passed through a hydroconversion reaction zone for hydroconversion reaction. The olefin content in the total feed of light naphtha and optionally added olefins is controlled to be 1% to 8% of the total feed weight, preferably 3% to 6%. The olefin content refers to the total content of butene, pentene, and hexene. The hydroconversion reaction zone is filled with two different hydroconversion catalysts, and the active metal content in the hydroconversion catalysts decreases sequentially along the flow direction.
[0009] (2) The effluent from the hydrogenation conversion reaction in step (1) enters the separation system and is separated to obtain hydrogen and hydrogenation conversion products.
[0010] According to the present invention, the optionally added olefin refers to the olefin content in the reaction system, which is selected based on the required olefin content in the total feed, and may or may not require the addition of olefins. The additional olefins preferably include at least one of butene, pentene, and hexene. The present invention does not impose any particular limitation on the respective proportions of butene, pentene, and hexene in the additional olefins.
[0011] According to the present invention, when the olefin content in light naphtha does not meet the requirement for the total olefin content in the feed, it is necessary to introduce additional olefins from an external source. Further, the additional olefins preferably include at least one of butene, pentene, and hexene.
[0012] According to the present invention, a fixed-bed reactor is used for the hydrogenation conversion reaction.
[0013] According to the present invention, the hydroconversion reaction zone is sequentially filled with a hydroconversion catalyst containing ZSM-5 molecular sieve and a hydroconversion catalyst containing mordenite along the material flow direction. That is, the material first reacts with the hydroconversion catalyst containing ZSM-5 molecular sieve, and then reacts with the hydroconversion catalyst containing mordenite. The hydroconversion catalyst containing ZSM-5 molecular sieve and the hydroconversion catalyst containing mordenite can be graded and packed in one or two catalyst beds along the material flow direction.
[0014] According to the present invention, along the flow direction, the ratio of the upstream catalyst loading volume to the downstream catalyst loading volume in two adjacent catalyst beds is 1:3 to 3:1, preferably 1:2 to 2:1.
[0015] According to the present invention, along the flow direction, the active metal content (in oxides) of the hydroconversion catalyst containing ZSM-5 molecular sieve is 1 to 20 percentage points higher than that of the hydroconversion catalyst containing mordenite, preferably 5 to 10 percentage points higher. Preferably, the content of Group VIB metals (in oxides) in the hydroconversion catalyst containing ZSM-5 molecular sieve is 1 to 18 percentage points higher (preferably 2 to 10 percentage points) higher than that in the hydroconversion catalyst containing mordenite, and the content of Group VIII non-precious metals (in oxides) in the hydroconversion catalyst containing ZSM-5 molecular sieve is 0 to 4 percentage points higher than that in the hydroconversion catalyst containing mordenite.
[0016] According to the present invention, the light naphtha is derived from one or more fractions obtained by processes such as hydrocracking, catalytic cracking or coking.
[0017] According to the present invention, the initial boiling point of the light naphtha is 10°C to 30°C, preferably 15°C to 25°C; and the final boiling point is 50°C to 100°C, preferably 55°C to 70°C.
[0018] According to the present invention, the content of C5-C6 isoalkanes in the hydrocracked light naphtha is 60wt% to 90wt%, preferably 70wt% to 80wt%; C 7+ The hydrocarbon content is 0-10 wt%, preferably 0.5 wt%-5 wt%; the C5-C6 n-alkanes content is 10 wt%-30 wt%, preferably 15 wt%-25 wt%; the C4 hydrocarbon content is 0-10 wt%, preferably 2 wt%-5 wt%; the cyclic hydrocarbon content is 0-10 wt%, preferably 2 wt%-5 wt%; based on a total weight of 100 wt% of the light naphtha. When the light naphtha is hydrocracked light naphtha, olefins need to be introduced from the outside, so that the olefin content in the total feed of light naphtha and the added olefins is 1%-8% of the total feed weight, preferably 3%-6%, where the olefin content refers to the total content of butene, pentene, and hexene.
[0019] According to the present invention, in the hydroconversion catalyst containing ZSM-5 molecular sieve, the SiO2 / Al2O3 molar ratio of the ZSM-5 molecular sieve is 10-50, and the specific surface area is 300-500 m². 2 / g, with a pore volume of 0.2–0.4 mL / g. In the hydroconversion catalyst containing mordenite, the SiO2 / Al2O3 molar ratio of the mordenite is 10–50, and the specific surface area is 300–600 m² / g. 2 / g, with a pore volume of 0.15~0.35mL / g.
[0020] Furthermore, in the ZSM-5 molecular sieve-containing hydroconversion catalyst, the content of ZSM-5 molecular sieve is 30wt% to 80wt%, preferably 40wt% to 70wt%, based on the weight of the catalyst.
[0021] According to the present invention, the hydroconversion catalyst containing ZSM-5 molecular sieve further includes a binder, preferably alumina. Further, in the hydroconversion catalyst containing ZSM-5 molecular sieve, the binder content (based on the weight of the catalyst) is 5 wt% to 65 wt%, preferably 10 wt% to 35 wt% (calculated as oxide), at a concentration of 10 wt% to 35 wt%.
[0022] According to the present invention, in the ZSM-5 molecular sieve-containing hydroconversion catalyst, the active metal component is selected from one or more of Group VIB metals and Group VIII non-noble metals of the periodic table. The Group VIB metals are preferably selected from one or more of molybdenum and tungsten, and the Group VIII non-noble metals are preferably selected from one or more of cobalt and nickel. Further, in the ZSM-5 molecular sieve-containing hydroconversion catalyst, based on the weight of the catalyst, the content of the Group VIB metals (calculated as oxides) is 5 wt% to 30 wt%, preferably 10 wt% to 20 wt%; and the content of the Group VIII non-noble metals (calculated as oxides) is 0.5 wt% to 15 wt%, preferably 3 wt% to 10 wt%.
[0023] According to the present invention, the specific surface area of the hydroconversion catalyst containing ZSM-5 molecular sieve is 200-400 m². 2 / g, with a pore volume of 0.15~0.40mL / g.
[0024] According to the present invention, the preparation method of the ZSM-5 molecular sieve-containing hydroconversion catalyst can be carried out according to conventional methods in the art. The preparation method includes the preparation of a support and the loading of an active metal component, wherein the support preparation process is as follows: a shape-selective cracking molecular sieve and a binder are mechanically mixed, shaped, dried, and calcined to form a catalyst support. The drying and calcination of the support can be performed under conventional conditions. The drying conditions are: drying at 100℃~150℃ for 1~12 hours. The calcination conditions are: calcination at 450℃~550℃ for 2.5~6.0 hours.
[0025] According to the present invention, in the preparation method of the ZSM-5 molecular sieve-containing hydroconversion catalyst, the method for loading the active metal component is a conventional method, such as kneading, impregnation, etc., with impregnation being preferred. The impregnation method can be a saturated impregnation method, an excess impregnation method, or a complex impregnation method, that is, impregnating the catalyst support with a solution containing the desired active metal component, followed by drying and calcination to obtain the hydroconversion catalyst. The drying conditions are: drying at 100℃~150℃ for 1~12 hours. The calcination conditions are: calcination at 450℃~550℃ for 2.5~6.0 hours.
[0026] Furthermore, in the hydroconversion catalyst containing mordenite, the content of the mordenite molecular sieve is 30wt% to 80wt%, preferably 40wt% to 70wt%, based on the weight of the catalyst.
[0027] According to the present invention, the hydroconversion catalyst containing mordenite further includes a binder, preferably alumina. Further, in the hydroconversion catalyst containing mordenite, the binder content (calculated as oxide) is 5 wt% to 65 wt%, preferably 10 wt% to 35 wt%, based on the weight of the catalyst.
[0028] According to the present invention, in the mordenite-containing hydroconversion catalyst, the active metal component is selected from one or more of Group VIB metals and Group VIII non-noble metals of the periodic table. The Group VIB metals are preferably selected from one or more of molybdenum and tungsten, and the Group VIII non-noble metals are preferably selected from one or more of cobalt and nickel. Further, in the mordenite-containing hydroconversion catalyst, based on the weight of the catalyst, the content of the Group VIB metals (calculated as oxides) is 5 wt% to 30 wt%, preferably 10 wt% to 20 wt%; and the content of the Group VIII non-noble metals (calculated as oxides) is 0.5 wt% to 15 wt%, preferably 3 wt% to 10 wt%.
[0029] According to the present invention, the specific surface area of the hydroconversion catalyst containing mordenite is 200-400 m². 2 / g, with a pore volume of 0.15~0.40mL / g.
[0030] According to the present invention, the preparation method of the hydroconversion catalyst containing mordenite can be carried out according to conventional methods in the art. The preparation method includes the preparation of a support and the loading of an active metal component, wherein the support preparation process is as follows: a shape-selective cracking molecular sieve and a binder are mechanically mixed, shaped, dried, and calcined to form a catalyst support. The drying and calcination of the support can be performed under conventional conditions. The drying conditions are: drying at 100℃~150℃ for 1~12 hours. The calcination conditions are: calcination at 450℃~550℃ for 2.5~6.0 hours.
[0031] According to the present invention, in the preparation method of the hydroconversion catalyst containing mordenite, the method of loading the active metal component is a conventional method, such as kneading, impregnation, etc., with impregnation being preferred. The impregnation method can be a saturated impregnation method, an excess impregnation method, or a complex impregnation method, that is, impregnating the catalyst support with a solution containing the desired active metal component, followed by drying and calcination to obtain the hydroconversion catalyst. The drying conditions are: drying at 100℃~150℃ for 1~12 hours. The calcination conditions are: calcination at 450℃~550℃ for 2.5~6.0 hours.
[0032] According to the present invention, the hydroconversion reaction conditions are as follows: reaction pressure is 0.5 MPa to 10.0 MPa, preferably 2.0 MPa to 5.0 MPa; reaction temperature is 250°C to 500°C, preferably 350°C to 450°C; and liquid hourly space velocity is 0.1 h⁻¹. -1 ~15.0h -1 0.5h is preferred -1 ~5.0h -1 The hydrogen-to-oil volume ratio is 10:1 to 2500:1, preferably 100:1 to 2000:1, and even more preferably 100:1 to 1000:1.
[0033] According to the present invention, the effluent from the hydrogenation conversion reaction zone in step (2) enters the separation system, and the separated hydrogen is a hydrogen-rich gas, which is used as recycled hydrogen.
[0034] According to the present invention, the hydroconversion products are fed into a steam cracking unit to produce ethylene, yielding the main target products ethylene, propylene, and butadiene, wherein the yields of the trienes are the mass percentages of the ethylene, propylene, and butadiene production relative to the hydroconversion product feed. The operating conditions for the steam cracking to produce ethylene are: reaction temperature 860–890°C, reaction pressure 0.1–0.3 MPa, and water-to-oil mass ratio 0.2–0.6.
[0035] Compared with the prior art, the present invention has the following beneficial technical effects:
[0036] (1) In the hydroconversion process, the first step is dehydrogenation. Accelerating the dehydrogenation process is a key step in realizing the conversion of light naphtha. Our research has shown that isoalkanes with smaller molecular weights are more difficult to dehydrogenate. By controlling the olefin content in the total feed, it can act as an initiator for the dehydrogenation reaction, increasing the dehydrogenation rate and accelerating the generation of carbocations, thus enabling the subsequent hydroconversion process. Further research has revealed that the difficulty of normalization of C5-C6 isoalkanes in hydrocracking light naphtha gradually increases with increasing molecular weight. C6 components are more prone to cracking. Using a high-metal-content ZSM-5 molecular sieve catalyst first can improve the cracking performance of the hydroconversion catalyst, preferentially and selectively hydrocracking C6 isoalkanes. Then, a low-metal-content mordenite catalyst can highly selectively cause C5 isoalkanes to undergo normalization. This invention uses molecular sieves with decreasing metal content and different reaction characteristics for gradation, achieving efficient conversion of different molecular weight hydrocarbons.
[0037] (2) The hydrogenation conversion process of the present invention has a simple process flow, low equipment investment and operating costs, and significantly increases the content of n-alkane in the hydrogenation product, thereby increasing the ethylene yield and total yield of trienes in the ethylene unit, and has broad promotion value. Attached Figure Description
[0038] Figure 1 This is a schematic diagram of the process flow according to an embodiment of the present invention;
[0039] Explanation of key figure labels:
[0040] 1-Hydrocracking light naphtha, 10-Additional olefins, 2-Hydrogen, 3-Hydroconversion reaction zone, 4-Hydroconversion reaction zone effluent, 5-Separation system, 6-Hydrogen, 7-Hydroconversion products. Detailed Implementation
[0041] The following examples further illustrate the function and effect of the present invention, but the following examples do not constitute a limitation on the method of the present invention.
[0042] Unless otherwise specified, all percentages in this invention refer to mass fractions.
[0043] The method of the present invention, such as Figure 1 As shown, the process includes: hydrocracking light naphtha 1, additionally added olefins 10 and hydrogen 2 are mixed and enter the hydroconversion reaction zone 3 for hydroconversion reaction, the hydroconversion reaction effluent 4 enters the separation system 5, the separated hydrogen 6 is recycled as circulating hydrogen, and the hydroconversion product 7 is directly used as ethylene feedstock.
[0044] In this invention, the hydroconversion catalysts containing ZSM-5 molecular sieves are designated as Cat-A followed by a number, such as Cat-A1, Cat-A2, Cat-A3, and Cat-A4. The hydroconversion catalysts containing mordenite are designated as Cat-B followed by a number, such as Cat-B1, Cat-B2, Cat-B3, and Cat-B4. The hydroconversion catalysts were prepared using a conventional active metal saturated impregnation method, and the physicochemical properties of the obtained catalysts are shown in Table 1.
[0045] In this invention, the properties of the ZSM-5 molecular sieve used in Cat-A are as follows: SiO2 / Al2O3 molar ratio is 30, and specific surface area is 400 m². 2 / g, pore volume 0.25cm 3 / g; The properties of the mordenite used in Cat-B are as follows: SiO2 / Al2O3 molar ratio is 20, and specific surface area is 450m². 2 / g, pore volume 0.25cm 3 / g.
[0046] The main properties of the hydrocracked light naphtha used in each example of this invention are shown in Table 3.
[0047] In this invention, the n-alkanes in Tables 4-5 include ethane, propane, n-butane, n-pentane, and n-hexane.
[0048] In this invention, the yield of n-alkanes = n-alkanes yield in hydrogenation conversion products / fresh feed amount × 100%, by mass.
[0049] In this invention, the fresh feedstock in each example includes hydrocracked light naphtha and additionally introduced olefins.
[0050] In this invention, the olefins additionally introduced into each example of hydrocracking light naphtha are a mixture of butene, pentene, and hexene.
[0051] In this invention, in the various hydroconversion reaction conditions, the hydrogen-to-oil volume ratio refers to the ratio of the total volume of hydrogen to the total feed, namely hydrocracking light naphtha and the additionally introduced olefins.
[0052] In this invention, in each example, the olefin content refers to the total content of butene, pentene, and hexene.
[0053] Example 1
[0054] The conversion method of hydrocracking light naphtha adopts, for example... Figure 1 The process is shown below. The method specifically includes:
[0055] (1) Hydrocracked light naphtha, additionally introduced olefins and hydrogen are mixed and carried out in the hydroconversion reaction zone; the hydroconversion reaction zone is sequentially filled with hydroconversion Cat-A1 and Cat-B1; the olefin content in the total feed is 3%;
[0056] (2) The hydrogenation conversion products are used directly as ethylene feedstock.
[0057] The process conditions and hydrogenation effect in this example are shown in Table 4.
[0058] Example 2
[0059] The conversion method of hydrocracking light naphtha adopts, for example... Figure 1 The process is shown below. The method specifically includes:
[0060] (1) Hydrocracked light naphtha, additionally introduced olefins and hydrogen are mixed and carried out in the hydroconversion reaction zone; the hydroconversion reaction zone is sequentially filled with hydroconversion Cat-A2 and Cat-B2; the olefin content in the total feed is 4%;
[0061] (2) The hydrogenation conversion products are used directly as ethylene feedstock.
[0062] The process conditions and hydrogenation effect in this example are shown in Table 4.
[0063] Example 3
[0064] The conversion method of hydrocracking light naphtha adopts, for example... Figure 1 The process is shown below. The method specifically includes:
[0065] (1) Hydrocracked light naphtha, additionally introduced olefins and hydrogen are mixed and hydroconverted in the hydroconversion reaction zone; the hydroconversion reaction zone is sequentially filled with hydroconversion Cat-A3 and Cat-B3; the olefin content in the total feed is 5%;
[0066] (2) The hydrogenation conversion products are used directly as ethylene feedstock.
[0067] The process conditions and hydrogenation effect in this example are shown in Table 4.
[0068] Example 4
[0069] The conversion method of hydrocracking light naphtha adopts, for example... Figure 1 The process is shown below. The method specifically includes:
[0070] (1) Hydrocracked light naphtha, additionally introduced olefins and hydrogen are mixed and carried out in the hydroconversion reaction zone; the hydroconversion reaction zone is sequentially filled with hydroconversion Cat-A1 and Cat-B3; the olefin content in the total feed is 6%;
[0071] (2) The hydrogenation conversion products are used directly as ethylene feedstock.
[0072] The process conditions and hydrogenation effect in this example are shown in Table 4.
[0073] Example 5
[0074] The conversion method of hydrocracking light naphtha adopts, for example... Figure 1 The process is shown below. The method specifically includes:
[0075] (1) Hydrocracked light naphtha, additionally introduced olefins and hydrogen are mixed and hydroconverted in the hydroconversion reaction zone; the hydroconversion reaction zone is sequentially filled with hydroconversion Cat-A2 and Cat-B2; the olefin content in the total feed is 7%;
[0076] (2) The hydrogenation conversion products are used directly as ethylene feedstock.
[0077] The process conditions and hydrogenation effect in this example are shown in Table 4.
[0078] Example 6
[0079] The conversion method of hydrocracking light naphtha adopts, for example... Figure 1 The process is shown below. The method specifically includes:
[0080] (1) Hydrocracked light naphtha, additionally introduced olefins and hydrogen are mixed and hydroconverted in the hydroconversion reaction zone; the hydroconversion reaction zone is sequentially filled with hydroconversion Cat-A1 and Cat-B5; the olefin content in the total feed is 3%;
[0081] (2) The hydrogenation conversion products are used directly as ethylene feedstock.
[0082] The process conditions and hydrogenation effect in this example are shown in Table 4.
[0083] Example 7
[0084] The conversion method of hydrocracking light naphtha adopts, for example... Figure 1 The process is shown below. The method specifically includes:
[0085] (1) Hydrocracked light naphtha, additionally introduced olefins and hydrogen are mixed and hydroconverted in the hydroconversion reaction zone; the hydroconversion reaction zone is sequentially filled with hydroconversion Cat-A4 and Cat-B2; the olefin content in the total feed is 4%;
[0086] (2) The hydrogenation conversion products are used directly as ethylene feedstock.
[0087] The process conditions and hydrogenation effect in this example are shown in Table 4.
[0088] Comparative Example 1
[0089] The difference from Example 1 is that the hydroconversion reaction zone is only filled with one type of hydroconversion catalyst, Cat-A1, and the total olefin content in the feed is the same as in Example 1.
[0090] The process conditions and hydrogenation effect in this example are shown in Table 5.
[0091] Comparative Example 2
[0092] The difference from Example 1 is that the hydroconversion reaction zone is only filled with one type of hydroconversion catalyst, Cat-B1, and the total olefin content in the feed is the same as in Example 1.
[0093] The process conditions and hydrogenation effect in this example are shown in Table 5.
[0094] Comparative Example 3
[0095] The difference from Example 1 is that the hydroconversion reaction zone is sequentially filled with hydroconversion catalysts Cat-A3 and Cat-B1, and the total olefin content in the feed is the same as in Example 1.
[0096] The process conditions and hydrogenation effect in this example are shown in Table 5.
[0097] Comparative Example 4
[0098] The difference from Example 1 is that the hydrogenation conversion reaction zone is sequentially filled with catalysts Cat-A1 and Cat-B4, and the total olefin content in the feed is the same as in Example 1.
[0099] The process conditions and hydrogenation effect in this example are shown in Table 5.
[0100] Comparative Example 5
[0101] The difference from Example 1 is that the olefin content in the total feed is 10%.
[0102] The process conditions and hydrogenation effect in this example are shown in Table 5.
[0103] Table 1. Composition and physicochemical properties of hydroconversion catalysts
[0104] catalyst Cat-A1 Cat-A2 Cat-A3 Cat-A4 Catalyst properties <![CDATA[Pore volume, cm 3 / g]]> 0.28 0.30 0.31 0.32 <![CDATA[Specific surface area, m 2 / g]]> 296 308 316 290 Catalyst composition ZSM-5 molecular sieve, wt% 50 50 50 45 Alumina, wt% 20 25 30 30 <![CDATA[MoO3,wt%]]> 25 20 15 20 NiO, wt% 5 5 5 5
[0105] Table 2 Composition and physicochemical properties of hydroconversion catalysts
[0106]
[0107]
[0108] Table 3. Main Properties of Hydrocracked Light Naphtha
[0109] raw material Hydrocracking light naphtha <![CDATA[C4 isoparaffin content, wt%]]> 1 <![CDATA[Content of n-C4 paraffin, wt%]]> 2 <![CDATA[Content of C5-C6 normal paraffin, wt%]]> 16 <![CDATA[C5-C6 isoparaffin content, wt%]]> 78 <![CDATA[C 7+ Hydrocarbon and cyclic hydrocarbon content, wt% 3 Initial boiling point, ℃ 24 Final boiling point, ℃ 64
[0110] Table 4. Process conditions and conversion results of each embodiment
[0111]
[0112] Table 5. Process conditions and conversion results for each comparative example.
[0113]
[0114]
[0115] Application examples
[0116] The products obtained from hydrogenation conversion in Examples 1 and 5 of this invention were fed into a steam cracking unit to produce ethylene, yielding the main target products ethylene, propylene, and butadiene. The operating conditions for the steam cracking to produce ethylene were: reaction temperature 880°C, reaction pressure 0.2 MPa, and water-to-oil mass ratio 0.4. The reaction results are shown in Table 6.
[0117] Table 6
[0118] Example 1 Comparative Example 5 Ethylene yield, wt% 35.4 32.7 Propylene yield, wt% 16.5 17.7 Butadiene yield, wt% 3.7 3.8
[0119] The specific embodiments of the present invention have been described in detail above; however, the present invention is not limited thereto. Within the scope of the inventive concept, various simple modifications can be made to the technical solutions of the present invention, including combining the various technical features in any other suitable manner. These simple modifications and combinations should also be considered as the content disclosed in the present invention and are all within the protection scope of the present invention.
Claims
1. A method for the hydroconversion of light naphtha, the method comprising: (1) Light naphtha, optionally added olefins, and hydrogen are mixed and passed through a hydroconversion reaction zone for hydroconversion reaction. The olefin content in the total feed of light naphtha and optionally added olefins is controlled to be 1% to 8% of the total feed weight, preferably 3% to 6%. The olefin content refers to the total content of butene, pentene, and hexene. The hydroconversion reaction zone is filled with two different hydroconversion catalysts, and the active metal content in the hydroconversion catalysts decreases sequentially along the flow direction. (2) The effluent from the hydrogenation conversion reaction in step (1) enters the separation system and is separated to obtain hydrogen and hydrogenation conversion products.
2. The method according to claim 1, characterized in that: The additional olefins include at least one of butene, pentene, and hexene.
3. The method according to claim 1, characterized in that: The light naphtha is derived from one or more fractions obtained through hydrocracking, catalytic cracking, or coking processes. Preferably, the initial boiling point of the light naphtha is 10℃~30℃, more preferably 15℃~25℃; and the final boiling point is 50℃~100℃, more preferably 55℃~70℃.
4. The method according to any one of claims 1-3, characterized in that: The light naphtha is hydrocracked light naphtha, and the content of C5-C6 isoalkanes in the hydrocracked light naphtha is 60wt% to 90wt%, preferably 70wt% to 80wt%; C 7+ The hydrocarbon content is 0-10 wt%, preferably 0.5 wt%-5 wt%; the C5-C6 n-alkanes content is 10 wt%-30 wt%, preferably 15 wt%-25 wt%; the C4 hydrocarbon content is 0-10 wt%, preferably 2 wt%-5 wt%; the cyclic hydrocarbon content is 0-10 wt%, preferably 2 wt%-5 wt%; and the total weight of the hydrocracked light naphtha is 100 wt%.
5. The method according to claim 1, characterized in that: The hydroconversion reaction zone is sequentially filled with a hydroconversion catalyst containing ZSM-5 molecular sieve and a hydroconversion catalyst containing mordenite along the material flow direction. Preferably, along the flow direction, the ratio of the upstream catalyst loading volume to the downstream catalyst loading volume in two adjacent catalyst beds is 1:3 to 3:1, more preferably 1:2 to 2:
1.
6. The method according to claim 5, characterized in that: In the ZSM-5 molecular sieve-containing hydroconversion catalyst, the active metal component is selected from one or more of Group VIB metals and Group VIII non-noble metals of the periodic table. The Group VIB metals are preferably selected from one or more of molybdenum and tungsten, and the Group VIII non-noble metals are preferably selected from one or more of cobalt and nickel. Preferably, the hydroconversion catalyst containing ZSM-5 molecular sieve further includes a binder, and the binder is preferably alumina.
7. The method according to claim 5 or 6, characterized in that: In the ZSM-5 molecular sieve-containing hydroconversion catalyst, based on the weight of the catalyst, the content of the ZSM-5 molecular sieve is 30wt% to 80wt%, preferably 40wt% to 70wt%; the content of the Group VIB metal, calculated as oxides, is 5wt% to 30wt%, preferably 10wt% to 20wt%; the content of the Group VIII non-noble metal, calculated as oxides, is 0.5wt% to 15wt%, preferably 3wt% to 10wt%; and the content of the binder, calculated as oxides, is 5wt% to 65wt%, preferably 10wt% to 35wt%.
8. The method according to claim 5, characterized in that: In the hydroconversion catalyst containing mordenite, the active metal component is selected from one or more of Group VIB metals and Group VIII non-precious metals of the periodic table. The Group VIB metals are preferably selected from one or more of molybdenum and tungsten, and the Group VIII non-precious metals are preferably selected from one or more of cobalt and nickel. Preferably, the hydroconversion catalyst containing mordenite further includes a binder, and the binder is preferably alumina.
9. The method according to claim 5 or 8, characterized in that: In the hydroconversion catalyst containing mordenite, based on the weight of the catalyst, the content of the mordenite molecular sieve is 30wt% to 80wt%, preferably 40wt% to 70wt%; the content of the Group VIB metal as oxide is 5wt% to 30wt%, preferably 10wt% to 20wt%; the content of the Group VIII non-precious metal as oxide is 0.5wt% to 15wt%, preferably 3wt% to 10wt%; and the content of the binder as oxide is 5wt% to 65wt%, preferably 10wt% to 35wt%.
10. The method according to any one of claims 6-9, characterized in that: Along the logistics direction, the active metal content of the hydroconversion catalyst containing ZSM-5 molecular sieve, calculated as oxides, is 1 to 20 percentage points higher than that of the hydroconversion catalyst containing mordenite, calculated as oxides, preferably 5 to 10 percentage points higher. Preferably, the content of Group VIB metals in the hydroconversion catalyst containing ZSM-5 molecular sieve, calculated as oxides, is 1 to 18 percentage points higher than that in the hydroconversion catalyst containing mordenite, preferably 2 to 10 percentage points higher; and the content of Group VIII non-precious metals in the hydroconversion catalyst containing ZSM-5 molecular sieve, calculated as oxides, is 0 to 4 percentage points higher than that in the hydroconversion catalyst containing mordenite.
11. The method according to claim 1, characterized in that: The hydrogenation conversion reaction conditions are as follows: reaction pressure is 0.5 MPa to 10.0 MPa, preferably 2.0 MPa to 5.0 MPa; reaction temperature is 250℃ to 500℃, preferably 350℃ to 450℃; liquid hourly space velocity is 0.1 h⁻¹. -1 ~15.0h -1 0.5h is preferred -1 ~5.0h -1 The hydrogen-to-oil volume ratio is 10:1 to 2500:1, preferably 100:1 to 2000:1, and even more preferably 100:1 to 1000:1.