A method for hydrogenating C4 fractions containing alkynes and dienes

Abstract

This invention provides a hydrogenation method for C4 fractions containing alkynes and dienes, comprising: sequentially passing the C4 fraction containing alkynes and dienes through a primary reactor and a secondary reactor connected in series to hydrogenate the C4 fraction; wherein the catalysts packed in the primary reactor and the secondary reactor may be the same or different, each independently selected from nickel-based non-precious metal hydrogenation catalysts; the nickel-based non-precious metal hydrogenation catalyst comprises an active component and a composite oxide support, wherein the active component is nickel, and the composite oxide support is selected from alumina-titanium oxide composite support, alumina-zirconia composite support, alumina-silica composite support, and titanium oxide-silica composite support. The method provided by this invention has the advantages of low energy consumption and high stability.

Description

Technical Field

[0001] This invention relates to the field of petrochemical technology, and more specifically to a hydrogenation method for C4 fractions containing alkynes and dienes. Background Technology

[0002] C4 fraction refers to a mixture of hydrocarbons containing four carbon atoms, including n-butane, isobutane, 1-butene, 2-butene, isobutene, 1,3-butadiene, 1,2-butadiene, 1-butyne, 2-butyne, and vinylacetylene. Separating these components from C4 fraction is extremely difficult and costly. Currently, many refineries in China face the challenge of how to rationally utilize C4 fraction. Generally, C4 fraction can only be treated as liquefied petroleum gas (LPG), which has low economic value and causes environmental pollution. In some refineries, the C4 fraction contains high levels of butadiene and alkynes, making it unstable and requiring combustion, often with the addition of a certain amount of LPG, resulting in even greater losses.

[0003] Selective hydrogenation of the C4 fraction to remove alkynes and dienes yields monoolefins that can be isomerized to produce isobutylene, enhancing the economic value of the C4 fraction and reducing environmental pollution. Complete hydrogenation of the C4 fraction to remove alkynes, dienes, and monoolefins yields alkanes that can serve as high-quality feedstock for ethylene cracking.

[0004] Patent CN1872819A provides a countercurrent selective hydrogenation method. A mixed C4 hydrocarbon feedstock and hydrogen gas are introduced into the column from the top and bottom of a countercurrent reactor via distributors. The downward-flowing hydrocarbon fraction and the upward-flowing hydrogen gas come into countercurrent contact on the catalyst surface. The reaction is carried out at a pressure of 0.1-3.0 MPa, a reaction temperature of 40-100℃, and a volume hourly space velocity of 1-20 h⁻¹. -1 The reaction proceeds downwards, while simultaneously, the lighter gases in the mixed C4 are stripped into the gas phase by hydrogen and flow out from the top of the reactor along with the unreacted hydrogen; the purified mixed C4 product flows out from the bottom of the reactor. The mixed C4 hydrocarbon feedstock referred to in this patent is a C4 mixture from an MTBE unit, and the process uses a noble metal catalyst with palladium as the main active component.

[0005] Patent CN102285859A discloses a selective hydrogenation process for C4 streams with high butadiene and alkyne content. The C4 stream is passed through one or more fixed-bed hydrogenation reactors with recirculation lines. Under the action of a hydrogenation catalyst in the reactor, butadiene and alkyne are hydrogenated and removed, producing butene. The stream then passes through a terminal reactor without recirculation lines to further remove the remaining butadiene and alkyne. This selective process is relatively complex, requiring two or more fixed-bed reactors in series. Separators, condensers, and compressors are needed between the reactors for circulation. This increases energy and material consumption, makes operation difficult, and results in high investment costs. Furthermore, this process uses a precious metal catalyst with palladium as the main active component, leading to high catalyst purchase costs. Summary of the Invention

[0006] To address the shortcomings of current methods for hydrogenating C4 fractions containing alkynes and dienes, such as high energy consumption and high equipment investment costs, one objective of this invention is to provide a hydrogenation method for C4 fractions containing alkynes and dienes. The hydrogenation method provided by this invention uses a low-temperature, highly active nickel-based non-precious metal catalyst to hydrogenate C4 fractions at a relatively low inlet temperature, reducing the unsaturated hydrocarbon content in the feedstock and increasing the added value of the product. The method employs a two-stage reactor series connection, where the second-stage reactor can directly utilize the outlet heat of the first-stage reactor, reducing energy consumption and improving operational stability.

[0007] The second objective of this invention is to provide an application of the hydrogenation method described above, corresponding to the first objective, in the full or selective hydrogenation of C4 fractions.

[0008] To achieve one of the above objectives, the technical solution adopted by the present invention is as follows:

[0009] A method for hydrogenating a C4 fraction containing alkynes and dienes, comprising:

[0010] The C4 fraction containing alkynes and dienes is hydrogenated by passing it sequentially through a first-stage reactor and a second-stage reactor connected in series.

[0011] The catalysts packed in the first-stage reactor and the second-stage reactor may be the same or different, and each is independently selected from nickel-based non-precious metal hydrogenation catalysts.

[0012] The nickel-based non-precious metal hydrogenation catalyst comprises a composite oxide support and an active component. The composite oxide support is selected from one or more of alumina-titanium oxide composite supports, alumina-zirconia composite supports, alumina-silica composite supports, titanium oxide-silica composite supports, and alumina-titanium oxide-zirconia composite supports, preferably alumina-titanium oxide composite supports or alumina-titanium oxide-zirconia composite supports. The active component is nickel.

[0013] In some preferred embodiments of the present invention, the hydrogenation treatment is carried out under liquid phase conditions.

[0014] In some preferred embodiments of the present invention, by adjusting the operating conditions of the first-stage reactor and the second-stage reactor, the C4 fraction can be fully hydrogenated to obtain alkanes, or the C4 fraction can be selectively hydrogenated to obtain monoolefins and alkanes.

[0015] In some preferred embodiments of the present invention, the operating conditions include one or more of the following: pressure, inlet temperature, volume hourly space velocity, hydrogen to fresh feed volume ratio, and recycle ratio.

[0016] In some preferred embodiments of the present invention, the C4 fraction is subjected to full hydrogenation under operating condition a to obtain the product alkane, wherein operating condition a includes:

[0017] The operating conditions for the first-stage reactor are: pressure 2.0 MPa–3.5 MPa, inlet temperature 25℃–60℃, and volumetric hourly space velocity (VHSV) 0.3 h⁻¹. -1 ~1.0h -1 The volume ratio of hydrogen to fresh feedstock is 20–500:1, and the recycling ratio is 10–30:1.

[0018] The operating conditions for the two-stage reactor are: pressure 2.0 MPa–3.5 MPa, inlet temperature 50°C–80°C, and volumetric hourly space velocity (VHSV) 0.5 h⁻¹. -1 ~3.0h -1 The volume ratio of hydrogen to fresh feedstock is 30–300:1, and the recycling ratio is 0–15:1.

[0019] According to the present invention, under operating condition a, the pressure of a reactor section can be listed as 2.0 MPa, 2.1 MPa, 2.2 MPa, 2.3 MPa, 2.4 MPa, 2.5 MPa, 2.6 MPa, 2.7 MPa, 2.8 MPa, 2.9 MPa, 3.0 MPa, 3.1 MPa, 3.2 MPa, 3.3 MPa, 3.4 MPa, 3.5 MPa, and any value between them.

[0020] According to the present invention, under operating condition a, the inlet temperature of a reactor section can be listed as 25°C, 26°C, 27°C, 28°C, 29°C, 30°C, 31°C, 32°C, 33°C, 34°C, 35°C, 36°C, 37°C, 38°C, 39°C, 40°C, 41°C, 42°C, 43°C, 44°C, 45°C, 46°C, 47°C, 48°C, 49°C, 50°C, 51°C, 52°C, 53°C, 54°C, 55°C, 56°C, 57°C, 58°C, 59°C, 60°C, and any value between them.

[0021] According to the present invention, under operating condition a, the volumetric space velocity of a reactor section can be listed as 0.3 h⁻¹. -1 0.4h -1 0.5h -1 0.6h -1 0.7h -1 0.8h -1 0.9h -1 1.0h -1 And any values ​​in between.

[0022] According to the present invention, under operating condition a, the volume ratio of hydrogen to fresh feed in a reactor section can be listed as 20:1, 50:1, 100:1, 150:1, 200:1, 250:1, 300:1, 350:1, 400:1, 450:1, 500:1 and any value between them.

[0023] According to the present invention, under operating condition a, the recycle ratio of a reactor section can be listed as 10:1, 15:1, 20:1, 25:1, 30:1 and any value between them.

[0024] According to the present invention, under operating condition a, the pressure of the two-stage reactor can be listed as 2.0 MPa, 2.1 MPa, 2.2 MPa, 2.3 MPa, 2.4 MPa, 2.5 MPa, 2.6 MPa, 2.7 MPa, 2.8 MPa, 2.9 MPa, 3.0 MPa, 3.1 MPa, 3.2 MPa, 3.3 MPa, 3.4 MPa, 3.5 MPa, and any value between them.

[0025] According to the present invention, under operating condition a, the inlet temperature of the two-stage reactor can be listed as 50℃, 51℃, 52℃, 53℃, 54℃, 55℃, 56℃, 57℃, 58℃, 59℃, 60℃, 61℃, 62℃, 63℃, 64℃, 65℃, 66℃, 67℃, 68℃, 69℃, 70℃, 71℃, 72℃, 73℃, 74℃, 75℃, 76℃, 77℃, 78℃, 79℃, 80℃, and any value between them.

[0026] According to the present invention, under operating condition a, the volumetric space velocity of the two-stage reactor can be listed as 0.5 h⁻¹. -1 0.6h -1 0.7h -1 0.8h -1 0.9h -1 1.0h -1 1.1h -1 1.2h -1 1.3h -1 1.4h -11.5h -1 1.6h -1 1.7h -1 1.8h -1 1.9h -1 2.0h -1 2.1h -1 2.2h -1 2.3h -1 2.4h -1 2.5h -1 2.6h -1 2.7h -1 2.8h -1 2.9h -1 3.0h -1 And any values ​​in between.

[0027] According to the present invention, under operating condition a, the volume ratio of hydrogen to fresh feed in the two-stage reactor can be listed as 30:1, 50:1, 100:1, 150:1, 200:1, 250:1, 300:1 and any value between them.

[0028] According to the present invention, under operating condition a, the recycle ratio of the two-stage reactor can be listed as 0:1, 5:1, 10:1, 15:1 and any value between them.

[0029] In some preferred embodiments of the present invention, the C4 fraction is selectively hydrogenated under operating condition b to obtain monoolefins and alkanes, wherein operating condition b includes:

[0030] The operating conditions for the first-stage reactor are: pressure 1.0 MPa–2.0 MPa, inlet temperature 20℃–35℃, and volumetric hourly space velocity (VHSV) 0.3 h⁻¹. -1 ~1.0h -1 The volume ratio of hydrogen to fresh feedstock is 20–500:1, and the recycling ratio is 10–30:1.

[0031] The operating conditions for the two-stage reactor are: pressure 0.5 MPa to 1.5 MPa, inlet temperature 30℃ to 55℃, and volumetric hourly space velocity (VHSV) 1.5 h⁻¹. -1 ~5.0h -1 The volume ratio of hydrogen to fresh feedstock is 30–300:1, and the recycling ratio is 0–15:1.

[0032] According to the present invention, the outlet temperature is determined by the inlet temperature and the recycle ratio. Under the above conditions, in operating condition a, the outlet temperature of the first-stage reactor is approximately 70°C to 90°C, and the outlet temperature of the second-stage reactor is approximately 90°C to 120°C. In operating condition b, the outlet temperature of the first-stage reactor is approximately 40°C to 55°C, and the outlet temperature of the second-stage reactor is approximately 50°C to 150°C.

[0033] According to the present invention, under operating condition a, the outlet temperature of a reactor section can be listed as 70°C, 71°C, 72°C, 73°C, 74°C, 75°C, 76°C, 77°C, 78°C, 79°C, 80°C, 81°C, 82°C, 83°C, 84°C, 85°C, 86°C, 87°C, 88°C, 89°C, 90°C, and any value between them.

[0034] According to the present invention, under operating condition a, the outlet temperature of the two-stage reactor can be listed as 90℃, 91℃, 92℃, 93℃, 94℃, 95℃, 96℃, 97℃, 98℃, 99℃, 100℃, 101℃, 102℃, 103℃, 104℃, 105℃, 106℃, 107℃, 108℃, 109℃, 110℃, 111℃, 112℃, 113℃, 114℃, 115℃, 116℃, 117℃, 118℃, 119℃, 120℃, and any value between them.

[0035] According to the present invention, under operating condition b, the pressure of a reactor section can be listed as 1.0 MPa, 1.1 MPa, 1.2 MPa, 1.3 MPa, 1.4 MPa, 1.5 MPa, 1.6 MPa, 1.7 MPa, 1.8 MPa, 1.9 MPa, 2.0 MPa and any value between them.

[0036] According to the present invention, under operating condition b, the inlet temperature of a reactor section can be listed as 20°C, 21°C, 22°C, 23°C, 24°C, 25°C, 26°C, 27°C, 28°C, 29°C, 30°C, 31°C, 32°C, 33°C, 34°C, 35°C, and any value between them.

[0037] According to the present invention, under operating condition b, the pressure of the two-stage reactor can be listed as 0.5MPa, 0.6MPa, 0.7MPa, 0.8MPa, 0.9MPa, 1.0MPa, 1.1MPa, 1.2MPa, 1.3MPa, 1.4MPa, 1.5MPa and any value between them.

[0038] According to the present invention, under operating condition b, the inlet temperature of the two-stage reactor can be listed as 30°C, 31°C, 32°C, 33°C, 34°C, 35°C, 36°C, 37°C, 38°C, 39°C, 40°C, 41°C, 42°C, 43°C, 44°C, 45°C, 46°C, 47°C, 48°C, 49°C, 50°C, 51°C, 52°C, 53°C, 54°C, 55°C, and any value between them.

[0039] In some preferred embodiments of the present invention, the nickel content is 8 wt% to 25 wt%, preferably 12 wt% to 22 wt%, based on the total mass of the nickel-based non-precious metal hydrogenation catalyst; and the content of the composite oxide support is 75 wt% to 92 wt%, preferably 78 wt% to 88 wt%.

[0040] In some preferred embodiments of the present invention, the composite oxide carrier is an alumina-titanium oxide composite carrier, and based on the total weight of the alumina-titanium oxide composite carrier, the alumina content is 60wt% to 90wt%, preferably 70wt% to 80wt%; the titanium oxide content is 10wt% to 40wt%, preferably 20wt% to 30wt%.

[0041] In some preferred embodiments of the present invention, the composite oxide carrier is an alumina-titanium oxide-zirconia composite carrier, wherein, based on the total weight of the alumina-titanium oxide-zirconia composite carrier, the alumina content is 65wt% to 75wt%; the titanium oxide content is 15wt% to 25wt%; and the zirconia content is 5wt% to 15wt%.

[0042] In some preferred embodiments of the present invention, the mass ratio of titanium oxide to zirconium oxide in the alumina-titanium oxide-zirconia composite carrier is (3-5):1, preferably (3.5-4.5):1. When the mass ratio of titanium oxide to zirconium oxide is within the above range, it is beneficial to reduce the inlet temperature of the reactor and improve the hydrogenation efficiency.

[0043] According to the present invention, the shape of the composite oxide carrier is selected from one or more of the following: granular, spherical, gear-shaped, leaf-shaped, strip-shaped, or clover-shaped, preferably clover-shaped.

[0044] In some preferred embodiments of the present invention, the total mass of the C4 fraction is used as the calculation basis, and the butadiene content in the C4 fraction is 2wt% to 30wt%, and the alkyne content is 0.5wt% to 40wt%.

[0045] In some preferred embodiments of the present invention, the reactor section is configured as one section in operation and one section in standby mode.

[0046] According to the present invention, the continuous operation of the dehydrogenation reaction can be ensured by having one reactor in operation and one in standby mode.

[0047] According to the present invention, the hydrogenation product of the first stage reactor can be directly fed into the second stage reactor as hydrogenation feedstock.

[0048] In this invention, the term "recycle ratio" refers to the volume ratio of the hydrogenated product used for recycling to the fresh feed. For example, if 50 mL of fresh C4 is fed while 200 mL of hydrogenated product is circulated, the recycling ratio is 4:1.

[0049] The beneficial effects of this invention are at least as follows:

[0050] Firstly, both reactor stages involve liquid-phase reactions, avoiding the process problems caused by the high-temperature vaporization of C4 fractions, reducing energy consumption, and making the unit's operating conditions easy to achieve, thus exhibiting excellent operability. Furthermore, the degree of hydrogenation in both stages can be flexibly adjusted to achieve diversified product production. It can produce high-quality ethylene cracking feedstock (generally requiring a monoolefin content of <5 wt%), as well as high-value C4 components such as 1-butene.

[0051] Secondly, the product from the first-stage reactor can be directly fed into the second-stage reactor as raw material, effectively utilizing the reaction temperature rise and reducing energy consumption. For example, in a 20,000-ton-per-year post-ether C4 hydrogenation unit, high-pressure steam can be saved at a rate equivalent to 700-1500 RMB per hour. Furthermore, the lower inlet temperature reduces side reactions in olefin polymerization. Detailed Implementation

[0052] The present invention will be described in detail below through embodiments, but the scope of protection of the present invention is not limited to the following description.

[0053] Unless otherwise specified in the examples, the procedures should be performed under standard conditions or conditions recommended by the manufacturer. Reagents or instruments whose manufacturers are not specified are all commercially available products.

[0054] In the following embodiments, unless otherwise specified, the Al2O3-TiO2 composite oxide support used in the first-stage reactor contains 85 wt% Al2O3 and 15 wt% TiO2. The Al2O3-TiO2 composite oxide support used in the second-stage reactor contains 75 wt% Al2O3 and 25 wt% TiO2.

[0055] In the following embodiments, unless otherwise specified, the Al2O3-TiO2-ZrO2 composite oxide support used has an Al2O3 content of 70wt%, a TiO2 content of 24wt%, and a ZrO2 content of 6wt%.

[0056] It is understood that the oxide content in the Al2O3-TiO2 composite oxide support disclosed in this invention is merely for the purpose of making the experimental samples clearer, and is not intended to emphasize the influence of the oxide content in the Al2O3-TiO2 composite oxide support on the experimental results. In the following embodiments, Al2O3-TiO2 composite oxide supports with other contents can also achieve technical effects comparable to the Al2O3-TiO2 composite oxide support described above.

[0057] In the following embodiments, unless otherwise specified, the content of each substance in the product is detected by gas chromatography.

[0058] In the following embodiments, unless otherwise specified, alkynes and dienes are not indicated, and the content of alkynes and dienes is below the detection limit.

[0059] In the following embodiments, unless otherwise specified, the component analysis of the hydrogenated feedstock is performed after the apparatus has been running for 96 hours.

[0060] Example 1

[0061] The residual liquid from a butadiene extraction unit was mixed with post-etherified C4 and used as the fresh feed at the inlet of a first-stage reactor, denoted as feed 1. The composition of feed 1 is as follows:

[0062]

[0063] In feedstock 1, C4 acetylene: 9.4 wt%, C4 diene: 3.27 wt%, mono-olefin: 58.76 wt%.

[0064] A single-stage reactor and a two-stage reactor connected in series are used as the hydrogenation unit. The hydrogenation product from the single-stage reactor is directly fed into the two-stage reactor as feedstock.

[0065] The first stage reactor is a 100mL scale-up evaluation reactor, loaded with 100mL of Ni / Al2O3-TiO2 hydrogenation catalyst, with a Ni content of 22wt% and the remainder being an Al2O3-TiO2 composite oxide support; the second stage reactor is also a 100mL scale-up evaluation reactor, loaded with 100mL of Ni / Al2O3-TiO2 hydrogenation catalyst, with a Ni content of 13wt% and the remainder being an Al2O3-TiO2 composite oxide support.

[0066] The operating conditions for the first stage reactor are: pressure 2.6 MPa, inlet temperature 22℃, and volumetric hourly space velocity (VHSV) 0.5 h⁻¹. -1 The volume ratio of hydrogen to fresh feedstock is 400:1, and the recycling ratio is 30:1.

[0067] The operating conditions for the two-stage reactor are: pressure 2.6 MPa, inlet temperature 60℃, and volumetric hourly space velocity (VHSV) 1.0 h⁻¹.-1 The volume ratio of hydrogen to fresh feedstock is 300:1, and the recycling ratio is 0:1.

[0068] The product composition at the outlet of the second-stage reactor is: no alkynes or diolefins, monoolefin content of 0.8 wt%, and the balance of C4 alkane.

[0069] Example 2

[0070] The raw materials and hydrogenation process used in this embodiment are the same as in Example 1, except that:

[0071] The first-stage reactor uses a 100mL scale-up evaluation reactor, loaded with 100mL of Ni / Al2O3-TiO2 hydrogenation catalyst, with a Ni content of 22wt% and the remainder being an Al2O3-TiO2 composite oxide support. The second-stage reactor also uses a 100mL scale-up evaluation reactor, loaded with 100mL of Ni / Al2O3-TiO2 hydrogenation catalyst, with a Ni content of 13wt% and the remainder being an Al2O3-TiO2 composite oxide support. The hydrogenation product from the first-stage reactor is fed into the second-stage reactor as a raw material.

[0072] The operating conditions for the first stage reactor are: pressure 3.2 MPa, inlet temperature 30℃, and volumetric hourly space velocity (VHSV) 0.6 h⁻¹. -1 The volume ratio of hydrogen to fresh feedstock is 400:1, and the recycling ratio is 20:1.

[0073] The operating conditions for the two-stage reactor are: pressure 3.1 MPa, inlet temperature 80℃, and volumetric hourly space velocity (VHSV) 1.2 h⁻¹. -1 The volume ratio of hydrogen to fresh feedstock is 200:1, and the recycling ratio is 3:1.

[0074] The product composition at the outlet of the second-stage reactor is: no alkynes or diolefins, monoolefin content of 0.2 wt%, and the balance of C4 alkane.

[0075] Example 3

[0076] The butadiene extraction unit uses C4 feedstock from tail gas (from Yanshan Petrochemical), denoted as feedstock 2. The composition of feedstock 2 is as follows: That is, the composition of the fresh feedstock at the inlet of the first reactor is as follows:

[0077] Vinylacetylene 26.21 wt%, 1-butyne 4.071 wt%, 2-butyne 0.186 wt%, 1,3-butadiene 4.582 wt%, 1,2-butadiene 0.803 wt%, trans-butene 3.18 wt%, n-butene 16.546 wt%, isobutene 28.973 wt%, cis-butene 1.029 wt%, isobutane 7.009 wt%, n-butane 7.047 wt%.

[0078] In feedstock 2, C4 acetylene: 30.467 wt%, C4 diene: 5.385 wt%, and C4 monoene: 49.728 wt%.

[0079] The first-stage reactor is a 100mL scale-up evaluation reactor, loaded with 100mL of Ni / Al2O3-TiO2 hydrogenation catalyst, with a Ni content of 15wt% and the remainder being an Al2O3-TiO2 composite oxide support; the second-stage reactor is also a 100mL scale-up evaluation reactor, loaded with 100mL of Ni / Al2O3-TiO2 hydrogenation catalyst, with a Ni content of 20wt% and the remainder being an Al2O3-TiO2 composite oxide support; the hydrogenation product from the first-stage reactor enters the second-stage reactor as feedstock.

[0080] The operating conditions for the first stage reactor are: pressure 2.8 MPa, inlet temperature 30℃, and volumetric hourly space velocity (VHSV) 0.4 h⁻¹. -1 The volume ratio of hydrogen to fresh feedstock is 500:1, and the recycling ratio is 20:1.

[0081] The operating conditions for the two-stage reactor are: pressure 2.8 MPa, inlet temperature 86℃, and volumetric hourly space velocity (VHSV) 0.6 h⁻¹. -1 The volume ratio of hydrogen to fresh feedstock is 150:1, and the recycling ratio is 10:1.

[0082] The product composition at the outlet of the second-stage reactor is: no alkynes or diolefins, and the content of monoolefins is 0.3 wt%.

[0083] Example 4

[0084] In this embodiment, raw material 2 is used, and a single-stage reactor and a two-stage reactor connected in series are employed as the hydrogenation unit. The operating conditions are:

[0085] The first-stage reactor is a 100mL scale-up evaluation reactor, loaded with 100mL of Ni / Al2O3-TiO2 hydrogenation catalyst, with a Ni content of 15wt% and the remainder being an Al2O3-TiO2 composite oxide support; the second-stage reactor is also a 100mL scale-up evaluation reactor, loaded with 100mL of Ni / Al2O3-TiO2 hydrogenation catalyst, with a Ni content of 20wt% and the remainder being an Al2O3-TiO2 composite oxide support; the hydrogenation product from the first-stage reactor enters the second-stage reactor as feedstock.

[0086] The operating conditions for the first stage reactor are: pressure 2.8 MPa, inlet temperature 26℃, and volumetric hourly space velocity (VHSV) 0.4 h⁻¹. -1 The volume ratio of hydrogen to fresh feedstock is 40:1, and the recycling ratio is 20:1.

[0087] The operating conditions for the two-stage reactor are: pressure 2.8 MPa, inlet temperature 47℃, and volumetric hourly space velocity (VHSV) 0.6 h⁻¹.-1 The volume ratio of hydrogen to fresh feedstock is 400:1, and the recycling ratio is 15:1.

[0088] The product composition at the outlet of the second-stage reactor is: no alkynes or diolefins, and the content of monoolefins is 0.3 wt%.

[0089] Example 5

[0090] In this embodiment, raw material 2 is used, and a single-stage reactor and a two-stage reactor connected in series are employed as the hydrogenation unit. The operating conditions are:

[0091] The first stage reactor is a 100mL scale-up adiabatic fixed-bed evaluation reactor, loaded with 100mL of Ni / Al2O3-TiO2 hydrogenation catalyst, with a Ni content of 12wt% and the remainder being an Al2O3-TiO2 composite oxide support; the second stage reactor is also a 100mL scale-up adiabatic fixed-bed evaluation reactor, loaded with 100mL of Ni / Al2O3-TiO2 hydrogenation catalyst, with a Ni content of 15wt% and the remainder being an Al2O3-TiO2 composite oxide support; the hydrogenation product from the first stage reactor enters the second stage reactor as feedstock.

[0092] The operating conditions for the first stage reactor are: pressure 1.2 MPa, inlet temperature 30℃, and volumetric hourly space velocity (VHSV) 0.7 h⁻¹. -1 The volume ratio of hydrogen to fresh feedstock is 40:1, and the recycling ratio is 20:1.

[0093] The operating conditions for the two-stage reactor are: pressure 1.0 MPa, inlet temperature 45℃, and volumetric space velocity 3 h⁻¹. -1 The volume ratio of hydrogen to fresh feedstock is 40:1, and the recycling ratio is 1:1.

[0094] The effluent composition of the second-stage reactor consists of: no alkynes, no diolefins, a monoolefin content of 77.09 wt%, and the balance being alkanes. Furthermore, the effluent gas contains 32.37 wt% butene-1.

[0095] Example 6

[0096] In this embodiment, raw material 2 is used, and a single-stage reactor and a two-stage reactor connected in series are employed as the hydrogenation unit. The operating conditions are:

[0097] The first-stage reactor is a 100mL scale-up evaluation reactor, loaded with 100mL of Ni / Al2O3-TiO2 hydrogenation catalyst, with a Ni content of 12wt% and the remainder being an Al2O3-TiO2 composite oxide support; the second-stage reactor is also a 100mL scale-up evaluation reactor, loaded with 100mL of Ni / Al2O3-TiO2 hydrogenation catalyst, with a Ni content of 15wt% and the remainder being an Al2O3-TiO2 composite oxide support; the hydrogenation product from the first-stage reactor enters the second-stage reactor as feedstock.

[0098] The operating conditions for the first stage reactor are: pressure 1.6 MPa, inlet temperature 25℃, and volumetric hourly space velocity (VHSV) 0.5 h⁻¹. -1 The volume ratio of hydrogen to fresh feedstock is 35:1, and the recycling ratio is 18:1.

[0099] The operating conditions for the two-stage reactor are: pressure 1.0 MPa, inlet temperature 38℃, and volumetric hourly space velocity (VHSV) 2.5 h⁻¹. -1 The volume ratio of hydrogen to fresh feedstock is 40:1, and the recycling ratio is 1:1.

[0100] The effluent composition of the second-stage reactor consists of no alkynes or diolefins, with a monoolefin content of 73 wt% and the remainder being alkanes. Furthermore, the effluent gas contains 28 wt% butene-1.

[0101] Example 7

[0102] The only difference from Example 1 is that the support used is an Al2O3-TiO2-ZrO2 composite oxide support, and the inlet temperature of the reactor is 16°C.

[0103] Under otherwise identical conditions, the product composition at the outlet of the two-stage reactor was measured to be: no alkynes or diolefins, a monoolefin content of 0.1 wt%, and the remainder being C4 alkane.

[0104] Comparative Example 1

[0105] Comparative Example 1 employed a one-stage reaction method, using IFP (Institute of Petroleum & Chemicals in France) LD365 type Pd / Al2O3 noble metal catalyst, with palladium as the main active component, as the catalyst for hydrogenation of feedstock 1. Specific methods included:

[0106] The reactor was a 100 mL scale-up evaluation reactor, loaded with 100 mL of Pd / Al₂O₃ catalyst, in which the Pd content was 0.33 wt% and the balance was Al₂O₃ support. The operating conditions were: pressure 2.6 MPa, inlet temperature 40 °C, and volumetric space velocity 0.8 h⁻¹. -1 The volume ratio of hydrogen to fresh feedstock is 400:1, and the recycling ratio is 20:1.

[0107] The reactor outlet product composition is as follows: alkyne content 0 wt%, diolefin content 0 wt%, and monoolefin content 3.5 wt%.

[0108] Comparing Comparative Example 1 with Example 1 of this application, it can be seen that the hydrogenation effect of the present invention is better than that of using expensive precious metal catalysts.

[0109] Comparative Example 2

[0110] The only difference between Comparative Example 2 and Example 1 is that the catalyst support for both the first and second stages in Comparative Example 2 is Al2O3. Under otherwise identical conditions, the hydrogenation result was the following product composition at the outlet of the second-stage reactor: 0 wt% alkyne, 0.2 wt% diolefins, and 15.6 wt% monoolefins.

[0111] Comparative Example 3

[0112] The only difference between Comparative Example 3 and Example 1 is that the catalyst support for both the first and second stages in Comparative Example 3 is TiO2 (specific surface area 70 μm). 2 / g, pore volume 0.3mL). Under otherwise identical conditions, the hydrogenation results showed the following product composition at the outlet of the two-stage reactor: alkyne content 0wt%, diene content 0wt%, and monoolefin content 4.7wt%.

[0113] Comparative Example 4

[0114] The only difference between Comparative Example 4 and Example 1 is that the catalyst support for both the first and second stages in Comparative Example 4 is Al2O3-SiO2 (SiO2 content is 20 wt%). Under otherwise identical conditions, the hydrogenation result was the following product composition at the outlet of the second-stage reactor: 0 wt% alkyne, 0.1 wt% diolefin, and 6.8 wt% monoolefin.

[0115] Comparative Example 5

[0116] The only difference between Comparative Example 5 and Example 1 is that the catalyst support for both the first and second stages in Comparative Example 5 is an alumina-zirconia composite support, with an alumina content of 96 wt% and a zirconia content of 4 wt%. Under otherwise identical conditions, the hydrogenation result was as follows: the product composition at the outlet of the second-stage reactor was 0 wt% alkyne, 0 wt% diolefin, and 4.3 wt% monoolefin.

[0117] It should be noted that the embodiments described above are only for explaining the present invention and do not constitute any limitation on the present invention. The present invention has been described with reference to typical embodiments, but it should be understood that the words used therein are descriptive and explanatory terms, not limiting terms. Modifications can be made to the present invention within the scope of the claims, and revisions can be made to the present invention without departing from the scope and spirit of the present invention. Although the present invention described herein relates to specific methods, materials, and embodiments, it does not mean that the present invention is limited to the specific examples disclosed herein; on the contrary, the present invention can be extended to all other methods and applications with the same function.

Claims

1. A method for hydrogenating a C4 fraction containing alkynes and dienes, comprising: The C4 fraction containing alkynes and dienes is hydrogenated by passing it sequentially through a first-stage reactor and a second-stage reactor connected in series. The catalysts packed in the first-stage reactor and the second-stage reactor may be the same or different, and each is independently selected from nickel-based non-precious metal hydrogenation catalysts. The nickel-based non-precious metal hydrogenation catalyst comprises a composite oxide support and an active component. The composite oxide support is an alumina-titanium oxide-zirconia composite support. Based on the total weight of the alumina-titanium oxide-zirconia composite support, the alumina content is 65wt%~75wt%, the titanium oxide content is 15wt%~25wt%, and the zirconia content is 5wt%~15wt%. The active component is nickel. By adjusting the operating conditions of the first-stage reactor and the second-stage reactor, the complete hydrogenation of the C4 fraction to obtain the product alkane is achieved. The operating conditions of the first-stage reactor are: pressure 2.0 MPa~3.5 MPa, inlet temperature 25℃~60℃, and volume hourly space velocity (VHSV) 0.3 h⁻¹. -1 ~1.0h -1 The hydrogen-to-fresh feed volume ratio is 20-500:1, and the recycle ratio is 10-30:

1. The operating conditions for the two-stage reactor are: pressure 2.0 MPa-3.5 MPa, inlet temperature 50℃-80℃, and volume hourly space velocity (VHSV) 0.5 h⁻¹. -1 ~3.0h -1 The volume ratio of hydrogen to fresh feedstock is 30~300:1, and the recycling ratio is 0~15:

1.

2. The hydrogenation method according to claim 1, characterized in that, The hydrogenation process is carried out under liquid phase conditions.

3. The hydrogenation method according to claim 1, characterized in that, Based on the total mass of the nickel-based non-precious metal hydrogenation catalyst, the nickel content is 8wt%~25wt%; the composite oxide support content is 75wt%~92wt%.

4. The hydrogenation method according to claim 3, characterized in that, The nickel content is 12wt% to 22wt%; and / or the content of the composite oxide support is 78wt% to 88wt%.

5. The hydrogenation method according to any one of claims 1-4, characterized in that, Based on the total mass of the C4 fraction, the butadiene content in the C4 fraction is 2wt%~30wt%, and the alkyne content is 0.5wt%~40wt%.

6. The hydrogenation method according to any one of claims 1-4, characterized in that, The reactor section is configured with one operating and one standby unit.

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