Hydrorefining method for alkynes and dienes

Abstract

The present invention relates to the field of selective hydrogenation, and in particular to a method for hydrogenating alkynes and dienes. The method comprises: heating a liquid phase C3 material to a gas phase, mixing the mixture with hydrogen, and selectively hydrogenating the mixture under the action of a supported palladium catalyst; the catalyst has a basic center, and the basic center enables the catalyst to have a pyrrole adsorption in-situ infrared spectrum at 40°C, with a peak at 3250-3370 cm ‑1 The N-H bond stretching vibration absorption peak appears in the range of 3160-3420cm in the in-situ infrared spectrum of the catalyst after pyrrole adsorption at 40 ° C and nitrogen purge at 0 minutes and 15 minutes. ‑1 The ratio of the peak heights of the absorption peaks within the range is greater than 5. This method has the advantages of low content of methyl acetylene and propadiene in the outlet, can prevent polymerization and coking during gas phase hydrogenation, has better propylene selectivity and lower C4+ production, thereby extending the operating cycle of the alkyne and diene hydrorefining process.

Description

Technical Field

[0001] The present invention relates to the field of selective hydrogenation, in particular to a method for hydrogenating and refining alkynes and diolefins. Background Art

[0002] The C3 fraction in petroleum processing often contains large amounts of methylacetylene and propadiene, which adversely affect subsequent processes. Catalytic selective hydrogenation is currently commonly used to remove these two substances. Three processes are primarily used to remove these substances from C3 streams in industrial plants: vapor-phase catalytic selective hydrogenation, liquid-phase catalytic selective hydrogenation, and catalytic distillation. The vapor-phase selective hydrogenation process heats the C3 liquid fraction to vaporize it, passing it through a catalyst bed for hydrogenation. This simple process utilizes low levels of precious metal catalysts, controls the concentration of methylacetylene and propadiene at the outlet, and saves separation energy in the downstream propylene distillation tower.

[0003] The catalytic reaction in the C3 gas-phase selective hydrogenation process typically operates at relatively high temperatures, which can easily lead to olefin polymerization and coking on the catalyst surface, shortening the catalyst's operating cycle. Currently, industrial operating cycles are generally less than six months, making the process difficult to scale up. Summary of the Invention

[0004] The purpose of the present invention is to overcome the problem of short operating cycle of gas-phase selective dehydrogenation in the prior art and provide a method for hydrogenation refining of alkynes and diolefins. The method utilizes a catalyst with a specific basic center to effectively improve the catalyst selectivity, inhibit the high-temperature polymerization of alkynes and diolefins, and extend the service life of the catalyst.

[0005] To achieve the above-mentioned object, the present invention provides a method for hydrogenating and refining alkynes and diolefins, which comprises: heating a liquid C3 material from the bottom of a deethanizer and / or the top of a depropanizer to a gas phase in a reactor loaded with a supported palladium catalyst, mixing the obtained gas phase material with hydrogen, and then selectively hydrogenating methylacetylene and propadiene;

[0006] The supported palladium catalyst has a basic center, and the basic center makes the catalyst have a pyrrole adsorption in-situ infrared spectrum at 40°C, 3250-3370cm -1 Moreover, after the catalyst was adsorbed with pyrrole at 40 ° C, nitrogen was used to purge the catalyst for 0 minutes, and the in-situ infrared spectrum at 3160-3420 cm -1 The peak height of the absorption peak in the range is similar to that of the 3160-3420 cm-1 absorption peak in the in-situ infrared spectrum measured by nitrogen purge for 15 minutes. -1 The ratio of the absorption peak height within the range is greater than 5.

[0007] The method described in the present invention is combined with the specific surface basic centers of the catalyst, and has the advantage of low content of methyl acetylene and propadiene in the outlet during the gas-phase hydrogenation of C3, can effectively prevent polymerization and coking during the gas-phase hydrogenation process, has better propylene selectivity and lower C4+ generation, thereby extending the service life of the C3 gas-phase selective hydrogenation technology. BRIEF DESCRIPTION OF THE DRAWINGS

[0008] Figure 1 The corresponding in-situ infrared spectrum of pyrrole adsorption of catalyst A prepared in Example 1 is shown.

[0009] Figure 2 The in situ infrared spectrum of pyrrole adsorption of catalyst A over time is shown; from top to bottom, the infrared absorption curves correspond to 10 min, 6 min, 4 min, 25 min and 0 min respectively. DETAILED DESCRIPTION

[0010] The endpoints of the ranges and any values ​​disclosed herein are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoints of each range, the endpoints of each range and 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 considered to be specifically disclosed herein.

[0011] The present invention provides a method for hydrogenating and refining alkynes and diolefins, which comprises: heating a liquid C3 material from the bottom of a deethanizer and / or the top of a depropanizer to a gas phase in a reactor loaded with a supported palladium catalyst, mixing the obtained gas phase material with hydrogen, and then selectively hydrogenating methylacetylene and propadiene;

[0012] The supported palladium catalyst has a basic center, and the basic center makes the catalyst have a pyrrole adsorption in-situ infrared spectrum at 40°C, 3250-3370cm -1 Moreover, after the catalyst was adsorbed with pyrrole at 40 ° C, nitrogen was used to purge the catalyst for 0 minutes, and the in-situ infrared spectrum at 3160-3420 cm -1 The peak height of the absorption peak in the range is similar to that of the 3160-3420 cm-1 absorption peak in the in-situ infrared spectrum measured by nitrogen purge for 15 minutes. -1 The ratio of the absorption peak height within the range is greater than 5.

[0013] In the present invention, the material to which the method is applicable is a liquid C3 material from the bottom of the deethanizer tower and / or the top of the depropanizer tower. Preferably, the liquid C3 material contains propylene, propane, methylacetylene, propadiene, ethane and optionally As. The content of each component may be a conventional content in the art. For example, preferably, in terms of molar amount, the total content of methylacetylene and propadiene in the liquid C3 material is 0.5-10 mol%, more preferably 2-7 mol%; the As content is 0-500 ppb, more preferably 0-50 ppb. In the present invention, the total content of methylacetylene and propadiene is calculated as the sum of the molar amounts of methylacetylene and propadiene.

[0014] Preferably, the ethane content in the liquid C3 material is 0-4 mol%, more preferably 0.5-1.5 mol%, based on molar amount.

[0015] Preferably, the propylene content in the liquid C3 material is 90-96 mol%, based on molar amount, and the remainder is propane and other impurities.

[0016] In the present invention, the liquid phase C3 material can be heated to the gas phase by conventional means in the art, for example, by heating the material through a heat exchanger to gasify it.

[0017] Preferably, the selective hydrogenation conditions include: the reactor inlet temperature is 60-90°C (for example, 60, 70, 80, 90°C and any range between any two values), more preferably 75-85°C; the reactor outlet temperature is 90-150°C (for example, 90, 100, 110, 120, 130, 140, 150°C and any range between any two values), more preferably 125-135°C; the reaction pressure is 0.5 MPa-3 MPa (for example, 0.5, 1, 1.5, 2, 2.5, 3 MPa and any range between any two values), more preferably 1 MPa-2.2 MPa, and the gas phase space velocity is 1000-6000 h -1 , preferably 2200-4200h -1 (For example, it can be 2200, 2500, 3000, 3500, 4000, 4200h -1 and any range between any two values).

[0018] Preferably, the ratio of the molar amount of hydrogen to the total molar amount of methylacetylene and propadiene is 1-5 (for example, it can be 1, 1.5, 2, 2.5, 3, 3.5, 4, 4.5, 5 and any range between any two values), preferably 1.2-1.8.

[0019] In the present invention, the reactor may be a conventional reactor in the art, such as an adiabatic fixed bed reactor. Those skilled in the art may select an appropriate size as needed.

[0020] In the present invention, preferably, the supported palladium catalyst comprises palladium, an optional modifying component and a carrier. That is, the supported palladium catalyst of the present invention can be a single palladium supported catalyst or a composite catalyst, comprising supported palladium and a modifying component.

[0021] The palladium on the catalyst surface may exist in the form of an oxidized state, a simple state, other palladium compound forms, or a mixture of two or more thereof.

[0022] The modifying component can be a conventional modifying component in the art, for example, it can be selected from at least one of Bi, Sb, Y, Mn, Zn, Group VIII elements other than palladium (such as Fe, Co, Ni, Ru, Rh, Os, Ir, Pt), Group IB elements (such as Cu, Ag, Au), Group VIB elements (such as Mo, W), Group IIIA elements (such as Ga, In, Tl), Group IVA elements (such as Si, Sn, Pb), rare earth elements (such as La, Ce, Pr, Nd, Pm, Sm, Eu, Gd, Tb, Dy, Ho, Er, Yb, Lu, Sc), alkali metal elements (such as Na, K), alkaline earth metal elements (such as Mg, Ca, Sr, Ba) and halogen elements (such as F, Cl, Br, I), more preferably selected from at least one of Zn, Cu, Mo, In, Y, Ag, Au and F.

[0023] The modified component can be loaded on the carrier together with palladium as a co-active component, or can be used as a modifier of the carrier and uniformly distributed in the carrier.

[0024] The carrier of the catalyst can be a carrier conventionally used in the art. For example, the carrier of the catalyst can be selected from at least one of aluminum oxide, titanium oxide, zirconium oxide, gallium oxide, silicon oxide, magnesium oxide, molecular sieves, zeolites, activated carbon, clay, bentonite and polymer materials (such as polyacrylates, polystyrene, carbon carriers, etc.).

[0025] Preferably, the specific surface area of ​​the carrier is 0.5-800m 2 / g, preferably 4-200m 2 / g, more preferably 15-110m 2 / g.

[0026] The shape of the carrier may include, but is not limited to, powder, granular, spherical, toothed ball, Raschig ring, strip, cylindrical, sheet or clover, etc.

[0027] Preferably, the palladium content in the supported palladium catalyst is 0.01-70wt% of the total weight of the carrier, calculated as the metal element, for example, it can be 0.01, 0.02, 0.05, 0.1, 0.5, 1, 5, 10, 20, 40, 70wt% and any range between any two values, more preferably 0.01-20wt%, further preferably 0.02-6wt%.

[0028] Preferably, the content of the modifying component in the supported palladium catalyst is 0-20 wt% of the total weight of the carrier, calculated as metal element, for example, it can be 0, 0.01, 0.05, 0.1, 0.5, 1, 5, 10, 15, 20 wt% and any range between any two values.

[0029] The supported palladium catalyst of the present invention has a basic center, which makes the catalyst have a pyrrole adsorption in-situ infrared spectrum at 40°C, 3250-3370cm -1 (For example, it can be 3250, 3260, 3270, 3280, 3290, 3300, 3310, 3320, 3330, 3340, 3350, 3360, 3370 cm -1 and any range between any two values) within the range of NH bond stretching vibration absorption peak, preferably only in the range of 3250-3370cm -1 In other words, the catalyst does not have an NH bond stretching vibration absorption peak in the range of 3160-3250 (excluding 3250) cm -1 and 3370 (excluding 3370)-3420cm -1 alkaline centers within the range.

[0030] Preferably, the supported palladium catalyst has a basic center, and the basic center makes the catalyst have a pyrrole adsorption in situ infrared spectrum at 40°C, 3290-3370 cm -1 The NH bond stretching vibration absorption peak appears in the range.

[0031] Preferably, after the catalyst is subjected to pyrrole adsorption at 40°C, the in-situ infrared spectrum at 3160-3420 cm-1 measured by nitrogen purge at 0 min is -1 The peak height of the absorption peak in the range is similar to that of the 3160-3420 cm-1 absorption peak in the in-situ infrared spectrum measured by nitrogen purge for 15 minutes. -1 The ratio of the absorption peak height within the range is greater than 10.

[0032] Preferably, the preparation method of the supported palladium catalyst comprises the following steps: (1) loading palladium and an optional modifying component onto a carrier through a solution containing a palladium precursor and a solution containing a modifying component precursor, and obtaining an intermediate after drying and calcining; (2) loading an alkaline compound onto the intermediate in the form of a solution containing an alkaline compound, and then drying and optionally calcining to obtain a catalyst.

[0033] Preferably, the amount of palladium used, calculated as the metal element, is such that the palladium content in the supported palladium catalyst is 0.01-70 wt % of the total weight of the support, for example, it can be 0.01, 0.02, 0.05, 0.1, 0.5, 1, 5, 10, 20, 40, 70 wt % and any range between any two values, more preferably 0.01-20 wt %, and even more preferably 0.02-6 wt %.

[0034] Preferably, the amount of the modifying component is such that, calculated as metal element, the content of the modifying component in the supported palladium catalyst is 0-20 wt% of the total weight of the carrier, for example, it can be 0, 0.01, 0.05, 0.1, 0.5, 1, 5, 10, 15, 20 wt% and any range between any two values.

[0035] Preferably, the amount of the basic compound is 0.1-25 wt% compared to the total weight of the carrier, for example, 0.1, 0.5, 1, 2, 4, 6, 8, 10, 15, 20, 25 wt% and any range between any two values.

[0036] The palladium and modifying component precursors can be pre-formulated as a solution and loaded onto the support by spraying or impregnation. When the catalyst includes a modifying component, such as when it serves as a co-active component, it can be loaded onto the support alone or simultaneously with the palladium. If the modifying component serves as a modifier for the support, it can be added during the support preparation process.

[0037] The palladium precursor can be a conventional acid or base or water-soluble substance in the art, such as one or more selected from palladium chloride, palladium nitrate, palladium acetate, palladium sulfate, palladium oxide and palladium metal organic compounds (such as palladium pivalate, octaethylporphyrin palladium, trimethylpalladium acetate, palladium trifluoroacetate, etc.).

[0038] The content of the palladium precursor in the solution containing the palladium precursor can be selected within a wide range, for example, the content of the palladium precursor in the solution containing the palladium precursor is 1-200 g / / L.

[0039] Preferably, the precursor of the modifying component is selected from at least one of halides (such as chlorides, bromides, iodides), nitrates, acetates, carbonates, sulfates, hydroxides, ammonium compounds and metal organic compounds (such as citrates, oxalates, etc.).

[0040] The content of the precursor of the modifying component in the solution containing the precursor of the modifying component can be selected within a wide range, for example, the content of the precursor of the modifying component in the solution containing the precursor of the modifying component is 0.1-400 g / L.

[0041] The solvents in the solution of the precursor containing palladium and the solution of the precursor containing the modifying component can each independently be water, diethyl ether, ethanol, isobutanol, and the like.

[0042] In the present invention, the loading method may be a conventional method in the art, for example, the loading method may be a spraying method or an immersion method, and the specific operation will not be described in detail.

[0043] In step (2), preferably, the basic compound is loaded in the form of a solution containing the basic compound.

[0044] The solvent in the solution containing the alkaline compound can be any solution that can dissolve the alkaline compound, and is preferably selected from at least one of water, methanol, ethanol, ether, acetone, tetrahydrofuran and N,N-dimethylformamide.

[0045] The basic compound may be an inorganic basic compound and / or an organic basic compound.

[0046] Preferably, the organic alkaline compound is at least one selected from dimethylamine, acetamide, trifluoroacetamide, pyridine, tetramethylethylenediamine, N,N-diisopropylethylamine, N-methylmorpholine, potassium ethoxide, potassium tert-butoxide and n-butyllithium.

[0047] Preferably, the inorganic alkaline compound is selected from at least one of ammonia, halides (such as KF, NaF, lithium chloride), and carbonates (such as sodium carbonate, potassium carbonate), preferably KF and / or lithium chloride.

[0048] Preferably, the content of the alkaline compound in the solution containing the alkaline compound is 0.1-70 wt %, for example, it can be 0.1, 0.5, 1, 5, 10, 20, 30, 40, 70 wt % and any range between any two values.

[0049] In a preferred embodiment of the present invention, the method comprises: (1) loading palladium on a carrier, drying and calcining to obtain an intermediate; (2) loading a basic compound on the intermediate, drying and optionally calcining to obtain a catalyst.

[0050] In another preferred embodiment of the present invention, the method comprises: (1) loading palladium and a modifying component onto a carrier, drying and calcining to obtain an intermediate; and (2) loading an alkaline compound onto the intermediate, drying and optionally calcining to obtain a catalyst.

[0051] In another preferred embodiment of the present invention, the method comprises: (1) loading a first modifying component onto a carrier, drying and calcining to obtain a modified carrier; loading palladium and an optional second modifying component onto the carrier, drying and calcining to obtain an intermediate; and (2) loading an alkaline compound onto the intermediate, drying and optionally calcining to obtain a catalyst.

[0052] In steps (1) and (2), when preparing the intermediate, modified support, or catalyst, the drying temperature can be independently 60-180°C, for example, 60, 80, 120, 160, 180°C, and any range between any two values. The drying time can be independently 1-48 hours, for example, 1, 5, 10, 20, 30, 40, 48 hours, and any range between any two values. It should be understood that the drying can be performed at least once, and the drying conditions can be different each time.

[0053] In step (1), the calcination temperature may be 300-1500°C, for example, 300, 400, 600, 800, 1000, 1200, 1400, 1500°C, and any range between any two values. Preferably, in the process of preparing the intermediate, the calcination temperature is 600-1500°C, for example, 600, 800, 1000, 1200, 1400, 1500°C, and any range between any two values. In the process of preparing the modified support, the calcination temperature is preferably 300-1000°C, for example, 300, 400, 600, 800, 1000°C, and any range between any two values.

[0054] In step (2), the calcination temperature is preferably 250-500°C, for example, it can be 200, 250, 300, 350, 400, 450, 500°C and any range between any two values.

[0055] In steps (1) and (2), the calcination time can be independently 2-24 h, for example, 2, 4, 8, 12, 16, 20, 24 h and any range between any two values.

[0056] In the steps (1) and (2) of the preparation method of the present invention, the drying and calcining can be independently carried out in an air atmosphere or under vacuum, preferably independently carried out in an air atmosphere.

[0057] In the present invention, the in-situ infrared spectrum of pyrolysis adsorption of the catalyst can be measured by the following method:

[0058] a) placing a powdered catalyst sample in an infrared cell, vacuum-treating it, and then heating it to 350°C at a rate of 20°C / min;

[0059] b) keeping the temperature at 350°C for 2 h in a vacuum state, and then cooling to 40°C at a cooling rate of 20°C / min;

[0060] c) Maintaining the temperature at 40°C, introduce nitrogen gas for 30 minutes at a nitrogen flow rate of 5 mL / min;

[0061] d) maintaining the temperature at 40° C., introducing gaseous pyrrole for adsorption for 10 minutes at a gas flow rate of 5 mL / min, and recording the in situ infrared spectrum of the sample;

[0062] e) Maintaining the temperature at 40°C, purge with nitrogen at a flow rate of 5 mL / min for 30 minutes, and record the in situ infrared spectrum of the sample.

[0063] Before testing, the granular catalyst sample should be ground into powder and filled into the in-situ sample cell with the surface kept flat. The purpose of steps a to c is to remove water and impurities adsorbed on the catalyst surface.

[0064] In the pyrrole adsorption step (step d), the in-situ infrared spectrum of the sample can be recorded at different times as needed, for example, the in-situ infrared spectrum of the sample can be recorded at 1 minute, 2 minutes, 3 minutes, 4 minutes, 5 minutes, 6 minutes, 7 minutes, 8 minutes, 9 minutes, and 10 minutes. In the in-situ infrared spectrum of pyrrole adsorption, 3160-3420 cm -1 The NH bond stretching vibration absorption peak appears in the range of 3160-3420cm, which corresponds to the base strength of the basic center on the catalyst surface. The higher the wave number of the peak position, the weaker the base strength of the basic center. -1 There are multiple NH bond stretching vibration absorption peaks in the range, indicating that the basic centers on the catalyst surface are diversified. The peak positions of pyrrole adsorption on different catalysts are quite different. Usually two or more peaks will overlap. In some cases, one peak will become the shoulder of another peak. In order to calculate the peak positions of each absorption peak, the commonly used data processing software can be used to analyze the peaks at 3160-3420cm -1 The absorption curve of the interval was fitted with peaks.

[0065] After purging with nitrogen, the intensity of the pyrrole infrared absorption peak gradually weakened. Spectrum 3160-3420cm after purging for 15 minutes -1 Absorption peak in the range 3160-3420cm and purge 0 minute spectrum -1 The peak height ratio of the absorption peaks within the range can be used to illustrate the adsorption capacity of the basic center on the catalyst surface for pyrrole, proving the existence of the basic center.

[0066] After the measurement, nitrogen purging can be maintained until the temperature drops to room temperature, with a nitrogen flow rate of 3-7 mL / min.

[0067] The present invention will be described in detail below through examples.

[0068] Unless otherwise specified, in the examples and comparative examples, the reagents used are all reagents commonly used in the art, and the methods adopted are all conventional methods in the art.

[0069] The Al2O3 carriers used below were purchased from Sinopec Catalyst (Beijing) Co., Ltd., with a specific surface area of ​​50-60m 2 / g.

[0070] Example 1

[0071] Prepare 250 mL of an aqueous solution of [(NH4)2Pd]Cl4 containing 0.3 g of Pd, [(NH4)2Ag]Cl3 containing 0.5 g of Ag, and ZnCl2 containing 1.1 g of Zn. Impregnate 500 g of a spherical Al2O3 support in the solution, dry at 105°C for 12 h, and calcine at 650°C for 15 h to obtain a Pd-Zn-Ag / Al2O3 intermediate.

[0072] Prepare 250 mL of an aqueous solution of KF containing 1.0 g of K, impregnate the Pd-Zn-Ag / Al2O3 intermediate in the solution, dry at 160°C for 4 h, and calcine at 300°C for 4 h to obtain catalyst A.

[0073] Example 2

[0074] Prepare 300 mL of an aqueous solution of Pd(NO3)2 containing 0.3 g of Pd and (NH4)2MoO4 containing 1.2 g of Mo, impregnate 500 g of a toothed ball-shaped carrier Al2O3 into the solution, dry at 140°C for 6 h, and calcine at 410°C for 3 h to obtain a Pd-Mo / Al2O3 intermediate;

[0075] Prepare 400 mL of a tetrahydrofuran solution containing 50 mL of N-methylmorpholine, impregnate the Pd-Mo / Al2O3 intermediate in the solution, and dry at 70°C for 20 h to obtain catalyst B.

[0076] Example 3

[0077] Prepare 300 mL of an aqueous solution of Pd(NO3)2 containing 0.3 g of Pd and (NH4)2MoO4 containing 1.2 g of Mo, impregnate 500 g of a toothed ball-shaped carrier Al2O3 into the solution, dry at 140°C for 6 h, and calcine at 410°C for 3 h to obtain a Pd-Mo / Al2O3 intermediate;

[0078] Prepare 400 mL of tetrahydrofuran solution containing 2 g of n-butyl lithium, impregnate the Pd-Mo / Al2O3 intermediate in the solution, and dry at 70°C for 20 h to obtain catalyst C.

[0079] Example 4

[0080] 400 mL of an ethanol solution of copper acetate containing 3.1 g of Cu was prepared, 500 g of a toothed spherical carrier Al2O3 was impregnated in the solution, dried at 75°C for 40 h, and calcined at 1100°C for 20 h to obtain a Cu-modified carrier Al2O3.

[0081] Prepare 300 mL of an aqueous solution of Pd(NO3)2 containing 0.5 g of Pd, impregnate the Cu-modified support Al2O3 in the solution, dry at 105°C for 6 h, and calcine at 700°C for 4 h to obtain a Pd-Cu / Al2O3 intermediate;

[0082] Prepare 250 mL of an aqueous solution containing 50 mL of tetramethylethylenediamine, immerse the Pd-Cu / Al2O3 intermediate in the solution, and dry at 75°C for 20 h to obtain catalyst D.

[0083] Comparative Example 1

[0084] Prepare 400 mL of ether solution containing 1.2 g of Pd in ​​Pd(Ac)2 solution and 5.0 g of Cs in Cs(Ac), impregnate 500 g of cloverleaf-shaped support Al2O3 into the solution, dry at 80°C for 48 h, and calcine at 450°C for 8 h to obtain Pd-Cs / Al2O3 intermediate;

[0085] 400 mL of K(Ac) ethanol solution containing 2.0 g of K was prepared, the Pd-Cs / Al2O3 intermediate was impregnated in the solution, and dried at 80°C for 30 h to obtain catalyst a.

[0086] Comparative Example 2

[0087] Prepare 265 mL of an isobutanol solution of HAuCl4 containing 0.5 g of Au, impregnate 500 g of a columnar Al2O3 support into the solution, dry at 110°C for 2 h, and calcine at 1270°C for 6 h to obtain an Au-modified Al2O3 support;

[0088] Prepare 300 mL of an aqueous solution of Pd(NO3)2 containing 4.8 g of Pd and Ga(NO3)3 containing 0.8 g of Ga, impregnate the Au-modified support Al2O3 in the solution, dry at 140°C for 12 h, and calcine at 820°C for 14 h to obtain a Pd-Ga-Au / Al2O3 intermediate;

[0089] Prepare 300 mL of acetone solution containing 110 mL of 4-dimethylaminopyridine (DMAP), immerse the Pd-Ga-Au / Al2O3 intermediate in the solution, and dry it at 165°C for 20 h to obtain catalyst b.

[0090] Comparative Example 3

[0091] Prepare 180 mL of a PdSO4 aqueous solution containing 2.5 g of Pd, spray the solution onto 500 g of a spherical Al2O3 carrier, dry at 140°C for 12 h, and calcine at 620°C for 10 h to obtain a Pd / Al2O3 intermediate;

[0092] 180 mL of an aqueous solution of NaHCO 3 containing 0.6 g of Na element was prepared and sprayed onto the Pd / Al 2 O 3 intermediate. The mixture was dried at 125° C. for 10 h and calcined at 445° C. for 16 h to obtain catalyst c.

[0093] Comparative Example 4

[0094] Prepare 400 mL of an aqueous solution of NaHCO3 containing 0.6 g of Na element, impregnate 500 g of a spherical carrier Al2O3 into the solution, dry at 125°C for 10 h, and calcine at 1050°C for 20 h to obtain a Na / Al2O3 intermediate.

[0095] 180 mL of a PdSO4 aqueous solution containing 2.5 g of Pd was prepared, and the solution was sprayed onto 500 g of a spherical carrier Al2O3. The solution was dried at 140°C for 12 h, and calcined at 620°C for 10 h to obtain catalyst d.

[0096] Comparative Example 5

[0097] 220 mL of a PdSO4 aqueous solution containing 2.5 g of Pd was prepared, and the solution was sprayed onto 500 g of a spherical carrier Al2O3, dried at 140°C for 6 h, and calcined at 620°C for 10 h to obtain catalyst e.

[0098] Comparative Example 6

[0099] 240 mL of an aqueous solution containing 2.5 g of Pd in ​​PdSO4 and 0.6 g of Na in NaHCO3 was prepared, and the solution was sprayed onto 500 g of a spherical carrier Al2O3, dried at 140°C for 6 h, and calcined at 620°C for 10 h to obtain catalyst f.

[0100] Test Example 1

[0101] This test example is used to illustrate the in-situ FTIR analysis of pyrrole adsorption on palladium-based catalysts.

[0102] The catalysts prepared in the examples and comparative examples were tested for pyrrole adsorption using a pyrrole in situ infrared analyzer (Thermo Nicolet 380). About 10 mg of powder sample was pressed into a thin sheet, fixed in an infrared cell, and first vacuum-purified (400°C, 1×10 -3 Pa) for 3 hours, cooled to 40°C, and the spectrum was scanned as background. The method for determining the in-situ infrared spectrum of pyrolyte adsorption of the catalyst is as follows:

[0103] a) placing a powdered catalyst sample in an infrared cell, vacuum-treating it, and then heating it to 350°C at a rate of 20°C / min;

[0104] b) maintaining the temperature at 350°C for 2 hours in a vacuum state, and then cooling the temperature to 40°C at a cooling rate of 20°C / min;

[0105] c) Maintaining the temperature at 40°C, introduce nitrogen gas for 30 minutes at a nitrogen flow rate of 5 mL / min;

[0106] d) Maintaining the temperature at 40°C, introduce gaseous pyrrole for 10 minutes at a gas flow rate of 5 mL / min, and record the sample's concentration at 1000-4000 cm-1 at 2, 4, 6, 8, and 10 minutes after the introduction of gaseous pyrrole. -1 In situ infrared spectra in wavenumber regions;

[0107] e) Maintaining the temperature at 40°C, purge with nitrogen at a flow rate of 5 mL / min for 30 minutes;

[0108] f) Maintain nitrogen purge until the temperature drops to room temperature with a nitrogen flow rate of 5 mL / min.

[0109] in, Figure 1 The corresponding in-situ infrared spectrum of pyrrole adsorption of catalyst A prepared in Example 1 is shown.

[0110] Figure 2 The in situ infrared spectra of pyrrole adsorption over time on Catalyst A are shown. From top to bottom, the infrared absorption curves correspond to 10 minutes, 6 minutes, 4 minutes, 25 minutes, and 0 minutes, respectively. 0 minutes represents the infrared absorption curve at the end of nitrogen purge; 4 minutes, 6 minutes, and 10 minutes represent the infrared absorption curves at the 4th, 6th, and 10th minutes of pyrrole adsorption; and 25 minutes represents the infrared absorption curve after 15 minutes of nitrogen purge after the end of pyrrole adsorption.

[0111] The in situ infrared spectrum of pyrrole adsorption was analyzed. Table 1 shows the peaks at 3160-3420 cm-1 at 10 minutes. -1 Within the range, the peak positions of the infrared absorption peaks of pyrrole of the catalysts prepared in the examples and comparative examples, as well as the peak height ratio H 10min / H 25min , where H 10min 3160-3420 cm-1 at 10 min of pyrrole adsorption -1 The highest peak height within the range (when there are two or more peaks, the highest peak height is used for calculation), H 25min 3160-3420 cm-1 at the end of pyrrole adsorption and nitrogen purge for 15 min -1 The highest peak height within the range (when there are two or more peaks, the peak height of the highest peak is used for calculation), and the peak height ratio is H 10min and H 25min The ratio.

[0112] Table 1

[0113]

[0114]

[0115] As shown in Table 1, the infrared peak position of pyrrole adsorption of the catalyst prepared by the method of the embodiment of the present invention is at a wavelength of 3250-3370 cm -1 The pyrrole adsorption infrared peak positions of the catalysts prepared in the comparative example are all greater than 3370 cm -1 After pyrrole adsorption was completed and nitrogen was used for purging, the pyrrole adsorbed on the catalyst surface was rapidly desorbed, and the peak height ratios of each catalyst were all above 10.

[0116] Test Example 2

[0117] This test example is used to illustrate the effect evaluation of liquid phase selective hydrogenation.

[0118] The process flow for the gas-phase hydrogenation of a C3 fraction stream utilizes a single-stage adiabatic fixed-bed reactor design. The C3 fraction stream composition at the reactor inlet is 93% propylene (mol), 4.7% methylacetylene and propadiene (mol), 1.2% ethane (mol), 10 ppb As, and the balance propane. The hydrogenation reaction space velocity is 3000 h / min. -1 , the pressure is 1.65MPa; the reactor inlet is equipped with hydrogen in a ratio of 1.55-1.85 of the molar amount of hydrogen to the total molar amount of methylacetylene and propadiene, the reactor inlet temperature is 82°C, and the outlet temperature is 130°C.

[0119] The commercially available catalyst is a supported palladium catalyst, and its operating cycle in industrial use is about 6 months.

[0120] The catalysts prepared in the examples and comparative examples and the above catalyst were used for gas phase hydrogenation, and the operating cycle (h), propylene selectivity (%) and C4+ production (mol%) were measured. The results are shown in Table 2.

[0121] The operating cycle refers to the time the system can operate when the total content of methylacetylene and propadiene at the outlet is controlled below 10 ppm.

[0122] The selectivity to propylene is calculated as:

[0123]

[0124] The amount of C4+ generated is the sum of the contents of C4 and above components in the analysis of the reactor outlet components.

[0125] Table 2

[0126] catalyst Operation cycle (h) Propylene selectivity (%) C4+ production (mol%) A 320 73 0.0001 B 310 69 0.0001 C 285 66 0.0002 D 280 64 0.0001 a 210 43 0.0005 b 205 39 0.0004 c 175 51 0.0005 d 120 26 0.1 e 80 20 0.4 f 130 32 0.2 Commercially available catalysts 260 30 0.1

[0127] As shown in Table 2, the gas-phase hydrogenation of methylacetylene and propadiene from the C3 fraction demonstrates that, while ensuring that the outlet methylacetylene and propadiene concentrations were less than 10 ppm, the run times and propylene selectivities of the various catalysts varied. The catalysts prepared in the Examples exhibited longer run times, better propylene selectivity, and lower C4+ formation than the catalysts prepared in the Comparative Examples and commercially available catalysts, demonstrating that modification of the catalyst surface with basic sites improves the catalyst's gas-phase hydrogenation performance.

[0128] The gas phase selective hydrogenation method provided in the present invention can effectively improve the selectivity of the catalyst, inhibit the high-temperature polymerization of alkynes and dienes, and extend the service life of the catalyst.

[0129] The preferred embodiments of the present invention have been described in detail above, but the present invention is not limited thereto. Within the technical concept of the present invention, various simple variations of the technical solution of the present invention may be made, including combining the various technical features in any other appropriate manner. These simple variations and combinations should also be regarded as disclosed in the present invention and fall within the scope of protection of the present invention.

Claims

1. A method for hydrogenating alkynes and diolefins, characterized in that: The method comprises: heating a liquid C3 material from the bottom of a deethanizer and / or the top of a depropanizer to a gas phase in a reactor loaded with a supported palladium catalyst, mixing the obtained gas phase material with hydrogen, and then performing selective hydrogenation of methylacetylene and propadiene; The supported palladium catalyst comprises palladium, a modifying component and a carrier. The supported palladium catalyst has a basic center. The basic center enables the catalyst to have a pyrrole adsorption in-situ infrared spectrum at 40°C, with a wavelength of 3250-3370 cm -1 Moreover, after the catalyst adsorbed pyrrole at 40 ° C, nitrogen was used to purge for 0 minutes, and the in-situ infrared spectrum at 3160-3420 cm -1 The peak height of the absorption peak in the range is similar to that of the 3160-3420 cm-1 absorption peak in the in-situ infrared spectrum measured by nitrogen purge for 15 minutes. -1 The ratio of the absorption peak height within the range is greater than 5; The pyrrole adsorption in-situ infrared spectrum of the catalyst was measured using the following method: a) The powdered catalyst sample was placed in an infrared cell, vacuum treated, and then heated to 350°C at a rate of 20°C / min. b) Keep at 350°C for 2 h in a vacuum state, then cool to 40°C at a cooling rate of 20°C / min; c) Maintain the temperature at 40°C and introduce nitrogen purge for 30 minutes at a nitrogen flow rate of 5 mL / min; d) Maintaining the temperature at 40°C, introduce gaseous pyrrole for adsorption for 10 minutes at a gas flow rate of 5 mL / min, and record the in situ infrared spectrum of the sample; e) Maintaining the temperature at 40°C, switch to nitrogen purge for 30 minutes at a nitrogen flow rate of 5 mL / min, and record the in situ FTIR spectrum of the sample.

2. The method according to claim 1, wherein The liquid phase C3 material contains propylene, propane, methylacetylene, propadiene, ethane and optionally As.

3. The method according to claim 2, wherein: Calculated by mole, the total content of methylacetylene and propadiene in the liquid phase C3 material is 0.5-10 mol%, and the As content is 0-500 ppb.

4. The method according to claim 3, wherein: Calculated by mole, the total content of methylacetylene and propadiene in the liquid phase C3 material is 2-7 mol%, and the As content is 0-50 ppb.

5. The method according to claim 1, wherein The selective hydrogenation conditions include: a reactor inlet temperature of 60-90° C.; a reactor outlet temperature of 90-150° C.; a reaction pressure of 0.5 MPa-3 MPa; and a ratio of the molar amount of hydrogen to the total molar amount of methylacetylene and propadiene of 1-5.

6. The method according to claim 1, wherein The carrier of the supported palladium catalyst is selected from at least one of aluminum oxide, titanium oxide, zirconium oxide, gallium oxide, silicon oxide, magnesium oxide, molecular sieves, activated carbon, clay and polymer materials; and / or The specific surface area of ​​the carrier is 0.5-800 m 2 / g; and / or The modified component in the supported palladium catalyst is selected from at least one of Bi, Sb, Y, Mn, Zn, Group VIII elements other than palladium, Group IB elements, Group VIB elements, Group IIIA elements, Group IVA elements, rare earth elements, alkali metal elements, alkaline earth metal elements and halogen elements.

7. The method according to claim 6, wherein: The specific surface area of ​​the carrier is 4-200m 2 / g.

8. The method according to claim 7, wherein: The specific surface area of ​​the carrier is 15-110m 2 / g.

9. The method according to any one of claims 1 to 8, wherein: The content of palladium in the supported palladium catalyst is 0.01-70 wt % of the total weight of the carrier, calculated as metal element; Calculated on the basis of the elements of the modifying component, the content of the modifying component in the supported palladium catalyst is less than 20 wt % of the total weight of the carrier and is not 0.

10. The method according to claim 9, wherein: Calculated as metal element, the content of palladium in the supported palladium catalyst is 0.01-20 wt % of the total weight of the carrier.

11. The method according to claim 10, wherein: Calculated as metal element, the content of palladium in the supported palladium catalyst is 0.02-6wt% of the total weight of the carrier.

12. The method according to claim 1, wherein The supported palladium catalyst has a basic center, and the basic center enables the catalyst to have a pyrrole adsorption in-situ infrared spectrum at 40° C. at 3290-3370 cm -1 NH bond stretching vibration absorption peak appears in the range; and / or After the catalyst adsorbed pyrrole at 40°C, nitrogen was used to purge the catalyst for 0 minutes, and the in-situ infrared spectrum at 3160-3420 cm -1 The peak height of the absorption peak in the range is similar to that of the 3160-3420 cm-1 absorption peak in the in-situ infrared spectrum measured by nitrogen purge for 15 minutes. -1 The ratio of the absorption peak height within the range is greater than 10.

13. The method according to claim 1, wherein The preparation method of a supported palladium catalyst comprises the following steps: (1) loading palladium and a modifying component onto a carrier through a solution containing a precursor of palladium and a solution containing a precursor of a modifying component, and obtaining an intermediate after drying and calcining; and (2) loading an alkaline compound onto the intermediate in the form of a solution containing an alkaline compound, and then drying and optionally calcining to obtain a catalyst.

14. The method according to claim 13, wherein The amount of palladium used is such that the content of palladium in the supported palladium catalyst is 0.01-70 wt % of the total weight of the support, calculated as the metal element; and / or The amount of the modifying component is such that the content of the modifying component in the supported palladium catalyst is less than 20 wt % of the total weight of the support and is not 0, calculated as the element of the modifying component; and / or Compared to the total weight of the carrier, the amount of the basic compound is 0.1-25 wt %.

15. The method according to claim 14, wherein Calculated as a metal element, the amount of palladium used is such that the palladium content in the supported palladium catalyst is 0.01-20 wt % of the total weight of the carrier.

16. The method according to claim 15, wherein Calculated as a metal element, the amount of palladium used is such that the palladium content in the supported palladium catalyst is 0.02-6 wt % of the total weight of the carrier.

17. The method according to claim 13, wherein: The palladium precursor is selected from at least one of palladium chloride, palladium nitrate, palladium acetate, palladium sulfate, palladium oxide and a metal organic compound of palladium; and / or The precursor of the modifying component is selected from at least one of halides, nitrates, acetates, carbonates, sulfates, hydroxides, ammonium compounds and metal organic compounds of the modifying component.

18. The method according to any one of claims 13 to 17, wherein: The solvent in the solution containing the basic compound is selected from at least one of water, methanol, ethanol, ether, acetone, tetrahydrofuran and N,N-dimethylformamide; and / or The basic compound is an inorganic basic compound and / or an organic basic compound.

19. The method according to claim 18, wherein The organic alkaline compound is at least one selected from dimethylamine, acetamide, trifluoroacetamide, pyridine, tetramethylethylenediamine, N,N-diisopropylethylamine, N-methylmorpholine, potassium ethoxide, potassium tert-butoxide and n-butyllithium; and / or The inorganic alkaline compound is selected from at least one of ammonia, halides and carbonates; and / or The content of the alkaline compound in the alkaline compound-containing solution is 0.1-70 wt %.

20. The method according to any one of claims 13 to 17, wherein: In step (1), the drying conditions include: temperature of 60-180°C; time of 1-48h; and / or The calcination temperature is 300-1500° C. and the calcination time is 2-24 hours.

21. The method according to any one of claims 13 to 17, wherein: In step (2), the drying temperature is 60-180°C; the drying time is 1-48 hours; and / or The calcination temperature is 250-500° C. and the calcination time is 2-24 hours.

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