CN105732260A - Selective hydrogenation method for C2 fraction - Google Patents
Selective hydrogenation method for C2 fraction Download PDFInfo
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Abstract
The invention relates to a selective hydrogenation method for a C2 fraction. In the method, a front hydrogenation process method with front depropanization is employed, wherein a material flow discharged from the top of a front depropanizing column in an ethylene apparatus is fed into a fixed bed reactor to perform the selective hydrogenation. A Pd-Ag-series catalyst is arranged in an adiabatic bed reactor. During preparation of the catalyst, an alumina-series carrier is combined with a bipyridine derivative having a hydroxyl group, wherein a metal complex is formed from the hydroxyl bipyridine derivative combined on the carrier and an active component. The method reduces influences on an apparatus due to temperature runaway, improves operation safety, ensures qualified hydrogenation on the acetylene, and improves the stability of operation in the apparatus.
Description
Technical field
The present invention relates to a kind of a kind of method selecting method of hydrotreating, particularly C 2 fraction selective hydrogenation to remove acetylene.
Background technology
Polymer grade ethylene production is the tap of petrochemical industry, and polymer grade ethylene and propylene are the most basic raw materials of downstream polymerisation device.Wherein ethylene processing industry is had extremely important impact by the selection hydrogenation of acetylene, except the outlet acetylene content of guarantee hydrogenation reactor is up to standard, selectivity of catalyst is excellent, the generation ethane that ethylene is the least possible can be made, to the yield of ethene improving whole technical process, improve device economic benefit significant.
Cracking C-2-fraction contains the acetylene that molar fraction is 0.5%-2.5%, when producing polyethylene, a small amount of acetylene in ethylene can reduce the activity of polymerization catalyst, and make the deterioration in physical properties of polymer, so the acetylene content in ethylene must be dropped to certain limit, could as the monomer of synthetic high polymer.Therefore acetylene separation and conversion are one of processes important in ethylene unit flow process.
In ethylene unit, catalysis selective hydrogenation is divided into front-end hydrogenation and back end hydrogenation, ethylene front-end hydrogenation and back end hydrogenation refer to that acetylene hydrogenation reactor is for domethanizing column position, hydrogenation reactor is front-end hydrogenation before being positioned at domethanizing column, and hydrogenation reactor is back end hydrogenation after being positioned at domethanizing column.In current C-2-fraction acetylene hydrogenation, more and more many processes adopting carbon two front-end hydrogenation, the feature of this process is that hydrogenation reactor is before domethanizing column, importantly flow process is predepropanization front-end hydrogenation, it is characterized in that cracking fraction separates through liquid phase, carries out the hydrogenation of carbon less than three fraction, complete acetylene to convert, and remove most propine allene
The dominant response occurred in the reactor is as follows:
Primary response
C2H2+H2→C2H4(1)
MAPD+H2→CH3-CH=CH2(2)
MAPD is propine and allene
Side reaction
C2H4+H2→C2H6(3)
C2H2+2H2→C2H6(4)
2C2H2+H2→C4H6(5)
C3H6+H2→C3H8(6)
In these are answered, reaction (1) and (2) is desirable to, and had both been stripped of acetylene, propine and allene, and had increased production again ethylene and propylene；Reaction (3), (4), (5) and (6) is undesirable.
Owing to there being substantial amounts of hydrogen in reaction mass, it is particularly important that selectivity of catalyst shows, and otherwise can cause the generation that side reaction is too much, cause catalytic reactor temperature runaway.During due to low-speed, the selectivity of reaction is low, it is easy to causing temperature runaway, safe air speed minimum at present is 4500/h, say, that when device air speed is lower than this numerical value, and reactor is just easy to temperature runaway, and the operation of device is brought threat.With carbon two back end hydrogenation process, carbon two front-end hydrogenation process important differences is that in back end hydrogenation process, hydrogen is artificially allocated into, it is possible to controlled by amounts of hydrogen to react the degree carried out.And in front-end hydrogenation process, hydrogen content is higher, need not joining hydrogen in hydrogenation process again, therefore that the control device of reaction is few, the performance requirement tackling catalyst mutually is just greatly improved.
For predepropanization front-end hydrogenation method, raising along with reaction temperature, catalyst selectivity declines, when catalyst selectivity drops to initial reaction temperature 1/3 time, think the maximum operation (service) temperature reaching catalyst, the difference of this temperature and initial reaction temperature is called the action pane of catalyst, and this temperature range is wider, and the processing safety of catalyst is just higher.Traditional catalyst is limited to due to selectivity, and this action pane generally only has 10～15 DEG C.
Current carbon two front-end hydrogenation mainly adopts fixed bed reactors, front-end hydrogenation technique for predepropanization, three sections of adiabatic reactor reactors of main employing, the acetylene of the front two reactor mainly elimination overwhelming majority, the 3rd section of reactor is used for removing propine (MA) and the allene (PD) of more than 50%.So the 3rd section of outlet acetylene is less than 1 μ L/L, MAPD less than 0.3% (v).
Patent US4484015 discloses a kind of predepropanization front-end hydrogenation method, and the catalyst that the method adopts is with Pd for main active component, with Alpha-alumina for carrier, adds promoter silver, is prepared for the C2 hydrogenation catalyst of function admirable with infusion process.This catalyst can effectively reduce the excessive hydrogenation of ethylene, reduces the risk of bed temperature runaway.The preparation method of the catalyst disclosed in this patent is to adopt infusion process.Because the surface polar groups of alpha-alumina supports is few, the impact being subject to impregnation liquid surface tension and solvation effect in the dipping and dried process of catalyst is especially apparent, and metal active constituent presoma is deposited on carrier surface with aggregate form.It addition, can not form strong interaction between slaine species and carrier after dipping, high-temperature roasting is easily caused metallic and migrates gathering and form big crystal grain.
Patent CN201110086174.0 discloses a kind of method of C 2 fraction selective hydrogenation, the catalyst that the method adopts, and with Pd for main active component, with Alpha-alumina for carrier, adds promoter silver.By adsorbing specific macromolecular compound on carrier, macromolecule wrapped layer is formed at carrier surface certain thickness, with with the compound of function base and high molecular weight reactive, can with the function base of active component complexation so as to have, on carrier surface function base, complex reaction is there is, it is ensured that active component is in order and high degree of dispersion by active component.Adopting this patented method, the specific macromolecular compound of carrier adsorption carries out chemisorbed by the hydroxyl of aluminium oxide and macromolecule, and the amount of carrier adsorption macromolecular compound is subjected to the hydroxyl value quantitative limitation of aluminium oxide；Not strong with the complexing of Pd through the macromolecule of functionalization, activity component load quantity does not reach requirement sometimes, goes back residual fraction active component in impregnation liquid, causes catalyst cost to improve；Adopt the method to prepare C2 hydrogenation catalyst and there is also the shortcoming that technological process is complicated.
Summary of the invention
A kind of method that it is an object of the invention to provide C-2-fraction predepropanization front-end hydrogenation, by selecting Pd, Ag catalyst of alloy structure, improves hydrogenation selectivity, improves yield of ethene, and this is for the production of ethylene, has important economic worth.
Present disclosure is: a kind of C 2 fraction selective hydrogenation method, adopt the front-end hydrogenation process of predepropanization, undertaken selecting hydrogenation by ethylene unit enters fixed bed reactors from the tower top effluent of predepropanization tower, to remove alkynes therein and alkadienes, it is characterized in that equipped with Pd-Ag series catalysts in adiabatic reactor reactor, Pd-Ag series catalysts refers to employing Al2O3Being carrier, with the quality of catalyst for 100%, wherein Pd content is 0.015～0.050%；Ag content is 0.030～0.20%, and the specific surface area of catalyst is 1～20m2/ g, pore volume is 0.15～0.50ml/g；This catalyst, in preparation process, is combined with hydroxyl dipyridyl derivatives by alumina series carrier, and hydroxyl dipyridyl derivatives forms metal complex with active component；Reaction condition is: adiabatic reactor reactor inlet temperature 45～100 DEG C, reaction pressure 3.5～4.5MPa, gas space velocity 3500～25000h-1。
The feature of the Pd-Ag series catalysts used in the present invention is: this catalyst is the PdAg-hydroxyl-bipyridyl/Al adopting the present invention2O3Prepared by the method for precursor.
The catalyst preparation process recommended, at least includes: loaded to by hydroxyl dipyridyl derivatives on alumina series carrier, and the cation of the hydroxyl unnecessary again through hydroxyl dipyridyl derivatives and/or nitrilo and Pd, Ag forms complex ion.
The hydroxyl dipyridyl derivatives of the present invention, preferably hydroxyl 2,2,-dipyridyl derivatives, hydroxyl 3,3 ,-dipyridyl derivatives, preferably hydroxyl 2,2 ,-dipyridyl derivatives, can there is good complex reaction with Pd, Ag in two nitrilo at hydroxyl unnecessary after being combined with aluminium oxide and ortho position because of it.
Defining the catalyst type of use in the present invention, such catalyst selectivity and traditional catalyst have bigger difference.
Principles of the invention is: in selective hydrogenation reaction, along with the catalyst activity component Pd, the Ag that use form alloy, the quantity of the hydrogen that caltalyst phase is adsorbed is greatly reduced, and the trend of acetylene generation deep hydrogenation is substantially reduced, and catalyst selectivity significantly improves.
The acquisition of this catalyst preferably includes following steps: by the organic solution of hydroxyl dipyridyl derivatives, impregnate Al2O3It is carrier, obtains hydroxyl-bipyridyl/Al after drying2O3Precursor, the mixed-cation solution impregnation hydroxyl-bipyridyl/Al of preparation Pd, Ag2O3Precursor, dry at 60 DEG C～150 DEG C, obtain PdAg-hydroxyl-bipyridyl/Al2O3Precursor.At 300～600 DEG C of roasting temperature 2～12h, obtain required catalyst.
Carrier of the present invention is alumina series carrier, for Al2O3Or mainly contain Al2O3, wherein also doped with other hopcalite, other oxide is titanium oxide, magnesium oxide and/or calcium oxide.Described Al2O3For θ, α or its mixing crystal formation.
In the present invention, carrier can be spherical, cylindrical, annular, bar shaped, cloverleaf pattern, Herba Galii Bungei shape etc..
Catalyst preparing of the present invention can adopt procedure below to implement, and this process can be divided into 3 steps to carry out.
A. hydroxyl-bipyridyl/Al2O3The preparation of precursor
By the organic solution of hydroxyl dipyridyl derivatives and Al2O3It is carrier mixing, makes solution be absorbed, at 20 DEG C～60 DEG C temperature, react 2～24h, take out solid particle, dry at 60 DEG C～150 DEG C, obtain hydroxyl-bipyridyl/Al2O3Precursor.The molal quantity of hydroxyl-bipyridyl/(Pd+Ag) is preferably 1～100.
B.PdAg-hydroxyl-bipyridyl/Al2O3The preparation of precursor
The mixed-cation solution of preparation Pd, Ag, with step A gained hydroxyl-bipyridyl/Al at 30 DEG C～100 DEG C temperature2O3Precursor reaction 2～24h, takes out solid particle, dry at 60 DEG C～150 DEG C, obtains PdAg-hydroxyl-bipyridyl/Al2O3Precursor.The volume of the mixed-cation solution of Pd, Ag is hydroxyl-bipyridyl/Al preferably2O3The 80%～120% of precursor cumulative volume；The ratio of the molal quantity of Ag and the molal quantity of Pd is preferably 0.4～5；Regulate pH value and be preferably 2.0～4.0.
C. the preparation of catalyst
PdAg-hydroxyl-bipyridyl/Al prepared by step B2O3Precursor is at 300～600 DEG C of roasting temperature 2～12h so that PdAg-hydroxyl-bipyridyl/Al2O3Precursor is changed into corresponding metal composite oxide, obtains catalyst.
Roasting preferably carries out in aerobic atmosphere.
When catalyst uses, the catalyst that above method can be prepared, use H in the reactor2Carry out reduction treatment, obtain reduction-state catalyst.
Front-end hydrogenation process to predepropanization, in entrance raw material, composition is mainly C-2-fraction 35～35% (v), wherein acetylene 0.4～0.8% (v), secondly it is methane 18～25% (v), hydrogen 12～25% (v), C3 fraction 8～15% (v), CO300～1500ppm.
After adopting this catalyst, the safe air speed of device can be reduced to 3500h-1.And safe air speed cannot be below 4500h in tradition method of hydrotreating-1, otherwise in reactor, temperature rise is too high, it may occur that temperature runaway, and the safety of device can be brought great threat.
Inventor have found that, after adopting the method for the present invention, decrease the impact that device is brought by temperature runaway, improve the safety of operation, can guarantee that the hydrogenation of acetylene is qualified simultaneously, reach to improve the stability of device operation.The method of the present invention is only limitted to the catalyst adopting the method for the present invention to prepare.
Accompanying drawing explanation
Fig. 1 is a kind of C2 hydrogenation process chart adopting predepropanization technique of the application present invention.1 oil scrubber；2 water scrubbers；3 caustic wash towers；4 exsiccators；5 predepropanization towers；6 carbon two front-end hydrogenation reactors；7 domethanizing columns；8 heat exchangers.
Detailed description of the invention
Analysis test method:
Specific surface area: GB/T-5816
Pore volume: GB/T-5816
Bulk density: Q/SY142-2006
Catalyst Pd, Ag assay: using plasma emission spectrometer records this catalyst Pd content and Ag content.Standard GB/T1537-94
Selective calculation method:
Ethylene selectivity: S=1-Δ ethane/Δ acetylene
Propylene Selectivity S=1-Δ propane/Δ (propine+allene)
Embodiment 1
Weighing Φ 4.5mm, length is 4.5mm, and specific surface area is 17m2/ g, pore volume is the column α-Al of 0.22ml/g2O3Carrier 500g.
By 39.42g4,4-dihydroxy-2,2-bipyridyl is dissolved in 700mL alcoholic solution, by above-mentioned carrier impregnation in above-mentioned solution, after standing 2h, make 4,4-dihydroxy-2,2-joins pyrrole and loads to completely after on alumina support, and 60 DEG C of dry 10h obtain hydroxyl-bipyridyl/Al2O3Precursor.
Weigh 0.18gPd (NO3)2、0.24gAgNO3, it is dissolved in 500mL deionized water, adds 10ml nitric acid and stir to being completely dissolved, adjusting pH value is 2.6, is configured to mixed solution.By above-mentioned hydroxyl-bipyridyl/Al2O3Precursor joins the solution prepared, and stirs 10min, stands 2h, pours out residual liquid, obtain PdAg-hydroxyl-bipyridyl/Al2O3Precursor (hydroxyl-bipyridyl molal quantity: (Pd+Ag)=100).After 120 DEG C of dry 4h at 550 DEG C of temperature roasting 2h in air atmosphere, obtain (Pd-Ag)/Al2O3Catalyst.Being positioned over before using in fixed-bed reactor, be 99.9% by hydrogen purity, air speed is 300h-1Gas, at 100 DEG C of temperature reduce 4h, obtain load type palladium-silver catalyst S-1.Recording this catalyst Pd content is 0.015%, and Ag content is 0.030%.
Comparative example 1
The preparation of catalyst
Weighing Φ 4.5mm, length is 4.5mm, and specific surface area is 17m2/ g, pore volume is the column α-Al of 0.22ml/g2O3Carrier 500g.
A, functionalized PVC/Al2O3Preparation
PVC8.9g is dissolved completely in 800ml oxolane (THF), makes PVC be deposited on Al 1h in the carrier impregnation weighed up to above-mentioned solution2O3Surface, pours out residual liquid, dries and obtains PVC/Al2O3Product.
Add 119.28g dicyandiamide and 2.0gNa2CO3, add above-mentioned PVC/Al2O3Reflux 4 hours, be cooled to room temperature, with deionized water wash to neutral, drying for standby.Obtain functionalized PVC/Al2O3.Reactive group Cl molal quantity=10 on chelating agent dicyandiamide molal quantity/macromolecular chain.
B, (Pd-Ag)-high-molecular complex/Al2O3The preparation of presoma
Weigh 0.18gPd (NO3)2、0.24gAgNO3, be dissolved in 500mL deionized water, add 10ml nitric acid stir to being completely dissolved, adjust pH value be 2.6, be configured to mixed solution, weigh prepared functionalized-macromolecule/Al2O3Presoma, by functionalized-macromolecule/Al2O3Join Pd (NO3)2, AgNO3Mixed solution in, adsorb 1h, pour out residual liquid, by above-mentioned product deionized water wash to neutral, 120 DEG C of dry 4h obtain (Pd-Ag)-polymer/Al2O3Presoma, reactive group Cl molal quantity/(Pd+Ag) molal quantity=100 on macromolecular chain).
C, catalyst preparation
By the presoma of above-mentioned preparation, in air atmosphere, 550 DEG C of roasting 2h, obtain oxidation state Pd-Ag/Al2O3Catalyst.Being positioned over before using in fixed-bed reactor, be 99.9% by hydrogen purity, air speed is 300h-1Gas, at 100 DEG C of temperature reduce 4h, obtain load type palladium-silver catalyst D-1.Recording this catalyst Pd content is 0.015%, and Ag content is 0.03%.
Adopting the front-end hydrogenation technique of predepropanization, reaction raw materials is from predepropanization column overhead, and composition is as shown in table 1.
Shown in table 1 hydrogenating materials table composed as follows
| Hydrogenating materials | H2 | C2H2 | C2H4 | C2H6 | CH4 | C3H6 | C3H8 | PDMA | CO | C4 + |
| Content (Φ %) | 20.0 | 0.7 | 35.1 | 4.2 | 25.0 | 12 | 2.0 | 0.50 | 0.2 | 0.3 |
Reaction condition: material air speed: 4000h-1；Operation pressure: 3.5MPa,；Loaded catalyst: 500ml.
Adiabatic reactor reactor, two-stage nitration tandem process, carry out hydrogenation reaction.Second stage reactor result after the examination of 1000 hours is as shown in table 2.
Table 2 1000 hours result of appraisal of two-stage nitration adiabatic reactor reactor
Embodiment 2
Weighing Φ 4.0 × 4.0mm, specific surface area is 7m2/ g, pore volume is the cylindrical vector 500g of 0.38ml/g, wherein containing α-Al2O3460g, TiO240g。
By 104.89g4,4-dihydroxy-2,2-bipyridyl is dissolved in 800mL alcoholic solution, by above-mentioned carrier impregnation in above-mentioned solution, after standing 8h, make 4,4-dihydroxy-2,2-bipyridyl loads to after on alumina support completely, 90 DEG C of dry 8h, obtains hydroxyl-bipyridyl/Al2O3Precursor.
Weigh 0.49gPd (NO3)2、0.79gAgNO3, it is dissolved in 500mL deionized water, adds 10ml nitric acid and stir to being completely dissolved, adjusting pH value is 2.5, is configured to mixed solution, by above-mentioned hydroxyl-bipyridyl/Al2O3Precursor joins the solution prepared, and stirs 60min, stands 8h, pours out residual liquid, obtain PdAg-hydroxyl-bipyridyl/Al after 110 DEG C of dry 4h of remaining solid2O3Precursor (hydroxyl-bipyridyl molal quantity: (Pd+Ag)=50).
By the presoma of above-mentioned preparation, 500 DEG C of roasting 4h in air atmosphere.Being positioned over before using in fixed-bed reactor, be 99.9% by hydrogen purity, air speed is 300h-1Gas, at 100 DEG C of temperature reduce 4h, obtain load type palladium-silver catalyst S-2.Recording this catalyst Pd content is 0.040%, and Ag content is 0.20%.
Comparative example 2
Catalyst preparing:
Weighing Φ 4.0 × 4.0mm, specific surface area is 7m2/ g, pore volume is the cylindrical vector 500g of 0.38ml/g, wherein containing α-Al2O3460g, TiO240g。
A, functionalized SAN/Al2O3Preparation
Weighing polystyrene SAN resin 30g, be dissolved in 600mlDMF solvent, under room temperature, stirring makes SAN resin be completely dissolved, and adds 40g oxammonium hydrochloride., adds 10gK2CO3, heating is completely dissolved to it.After stirring half an hour, by Al2O3Carrier 500g adds above solution, drips 400ml ethanol, and is stirred continuously, and takes out product after 1 hour, and washing, to neutral, after drying, obtains functionalized SAN/Al2O3.With molar basis, reactive group CN molal quantity=1.2 in chelating agent oxammonium hydrochloride. molal quantity/macromolecule.
B, (Pd-Ag)-polymer/Al2O3The preparation of presoma
Weigh 0.49gPd (NO3)2、0.79gAgNO3、6.34gK2CO3It is dissolved in 1200ml deionized water, takes the functionalized-SAN/Al prepared2O3Presoma joins Pd (NO3)2、AgNO3Mixed solution in, pour out residual liquid after absorption 1h, by above-mentioned product deionized water wash to neutral, at 110 DEG C, dry 6h, obtains (Pd-Ag)-polymer/Al2O3Presoma.Reactive group CN molal quantity/(Pd+Ag) molal quantity=42.10 in macromolecule.
C, catalyst preparation
By the presoma of above-mentioned preparation, 500 DEG C of roasting 4h in air atmosphere, obtain (Pd-Ag)/Al2O3Catalyst S-2.Recording this catalyst Pd content is 0.037%, and Ag content is 0.18%.
Adopt the front-end hydrogenation technique of predepropanization, as shown in Figure 1.Reaction raw materials is from predepropanization column overhead, and composition is as shown in table 3.
Table 3 hydrogenating materials forms
| Hydrogenating materials | H2 | C2H2 | C2H4 | C2H6 | CH4 | CO | C3H6 | C3H8 | PDMA |
| Content (Φ %) | 17.95 | 0.45 | 43 | 11.2 | 12 | 0.04 | 12 | 2.9 | 0.46 |
Reaction process condition: the front-end hydrogenation process of predepropanization, two sections of adiabatic reactor reactors.
Material air speed: 20000h-1, operate pressure: 3.8MPa, loaded catalyst: 500ml.
Reaction result:
Two reactor result after the examination of 1000 hours is as shown in the table:
Table 1000 hours result of appraisal of 4 three sections of adiabatic reactor reactors
Embodiment 3
Weighing Φ 3.7mm, specific surface area is 20m2/ g, pore volume is 0.38ml/g, heap spherical alumina support 500g, Al than 0.85g/ml2O3Mixing crystal formation for θ, α.
By 4.4g6,6'-dihydroxy-3,3'-bipyridyl is dissolved in 600mL alcoholic solution, by above-mentioned carrier impregnation in above-mentioned solution, after standing 12h, make 6,6'-dihydroxy-3,3'-bipyridyl loads to after on alumina support completely, 120 DEG C of dry 4h, obtains hydroxyl-bipyridyl/Al2O3Precursor.
Weigh 0.61gPd (NO3)2,1.57gAgNO3, it is dissolved in 500mL deionized water, adds 10ml nitric acid and stir to being completely dissolved, adjusting pH is 3.0, is configured to mixed solution, by above-mentioned hydroxyl-bipyridyl/Al2O3Precursor joins the solution prepared, and stirs 60min, stands 12h, pours out residual liquid, and at remaining solid 100 DEG C, dry 8h obtains PdAg-hydroxyl-bipyridyl/Al2O3Precursor (hydroxyl-bipyridyl molal quantity: (Pd+Ag)=2).
By the presoma of above-mentioned preparation, 450 DEG C of roasting 6h in air atmosphere.Being positioned over before using in fixed-bed reactor, be 99.9% by hydrogen purity, air speed is 300h-1Gas, at 100 DEG C of temperature reduce 4h, obtain load type palladium-silver catalyst S-3.Recording this catalyst Pd content is 0.050%, and Ag content is 0.20%.
Comparative example 3
Weighing Φ 3.7mm, specific surface area is 27m2/ g, pore volume is 0.38ml/g, heap spherical alumina support 500g, Al than 0.85g/ml2O3Mixing crystal formation for θ, α.
Weigh 0.61gPd (NO3)2,1.57gAgNO3, it is dissolved in 500mL deionized water, adds 10ml nitric acid and stir to being completely dissolved, adjusting pH is 3.0, and by concussion after this solution spraying to above-mentioned carrier 0.5 hour, after drying, in air atmosphere, 500 DEG C of roasting 8h obtained (Pd-Ag)/Al2O3Catalyst.Being positioned over before using in fixed-bed reactor, be 99.9% by hydrogen purity, air speed is 300h-1Gas, at 100 DEG C of temperature reduce 4h, obtain load type palladium-silver catalyst D-3.Recording this catalyst Pd content is 0.050%, and Ag content is 0.20%.
Adopting the front-end hydrogenation technique of predepropanization, reaction raw materials is from predepropanization column overhead, and composition is as shown in table 5.
Table 5 hydrogenating materials forms
| Hydrogenating materials | H2 | C2H2 | C2H4 | C2H6 | C3H6 | C3H8 | PDMA | CO | C4 + |
| Content (v/v%) | 17.0 | 0.9 | 40.0 | 10.0 | 29.0 | 2.0 | 0.7 | 0.1 | 0.3 |
Reaction process condition: predepropanization front-end hydrogenation technique, three sections of adiabatic reactors；Material air speed: 10000h-1；Operation pressure: 3.9MPa, loaded catalyst: 500ml.
Table 1000 hours result of appraisal of 6 three sections of adiabatic reactor reactors
Embodiment 4
Weighing Φ 4.0mm, high 4.0mm, specific surface area is 20m2/ g, pore volume is spherical alumina support 500g, the Al of 0.40ml/g2O3Mixing crystal formation for θ, α.
By 47.2g6,6'-dihydroxy-3,3'-bipyridyl is dissolved in 600mL alcoholic solution, by above-mentioned carrier impregnation in above-mentioned solution, after standing 10h, make 6,6'-dihydroxy-3,3'-bipyridyl loads to after on alumina support completely, 100 DEG C of dry 6h, obtains hydroxyl-bipyridyl/Al2O3Precursor.
Weigh 0.37gPd (NO3)2,1.18gAgNO3, it is dissolved in 450mL deionized water, adds 10ml nitric acid and stir to being completely dissolved, adjusting pH is 2.5, is configured to mixed solution, by above-mentioned hydroxyl-bipyridyl/Al2O3Precursor joins the solution prepared, and stirs 60min, stands 10h, pours out residual liquid, and at remaining solid 90 DEG C, dry 10h obtains PdAg-hydroxyl-bipyridyl/Al2O3Precursor (hydroxyl-bipyridyl molal quantity: (Pd+Ag)=30).
By the presoma of above-mentioned preparation, 600 DEG C of roasting 2h in air atmosphere.Being positioned over before using in fixed-bed reactor, be 99.9% by hydrogen purity, air speed is 300h-1Gas, at 100 DEG C of temperature reduce 4h, obtain load type palladium-silver catalyst S-4.Recording this catalyst Pd content is 0.030%, and Ag content is 0.15%.
Comparative example 4
Weighing Φ 4.0mm, high 4.0mm, specific surface area is 27m2/ g, pore volume is spherical alumina support 500g, the Al of 0.40ml/g2O3Mixing crystal formation for θ, α.
Weigh 0.37gPd (NO3)2,1.18gAgNO3, it is dissolved in 450mL deionized water, adds 10ml nitric acid and stir to being completely dissolved, adjusting pH is 2.5, and by concussion after this solution spraying to above-mentioned carrier 0.5 hour, after drying, in air atmosphere, 600 DEG C of roasting 2h obtained (Pd-Ag)/Al2O3Catalyst.Being positioned over before using in fixed-bed reactor, be 99.9% by hydrogen purity, air speed is 300h-1Gas, at 100 DEG C of temperature reduce 4h, obtain load type palladium-silver catalyst D-3.Recording this catalyst Pd content is 0.030%, and Ag content is 0.15%.
Adopting the front-end hydrogenation technique of predepropanization, reaction raw materials is from predepropanization column overhead, and composition is as shown in table 7.
Table 7 hydrogenating materials forms
| Hydrogenating materials | H2 | C2H2 | C2H4 | C2H6 | C3H6 | C3H8 | PDMA | CO | C4 + |
| Content (v/v%) | 16.0 | 0.9 | 39.0 | 9.5 | 29.5 | 2.0 | 0.7 | 0.1 | 0.3 |
Reaction process condition: predepropanization front-end hydrogenation technique, three sections of adiabatic reactors；Material air speed: 10000h-1；Operation pressure: 3.9MPa, loaded catalyst: 500ml.
Table 1000 hours result of appraisal of 8 three sections of adiabatic reactor reactors
Can be seen that from above embodiments, compared with adopting tradition preparation catalyst, with adopt organic polymer grafted functional group load on a catalyst support, the solution of this carrier impregnation activity Pd, Ag obtains the method for organic polymer metal complex again prepare catalyst and compare, after adopting the method for the present invention, the activity of C-2-fraction hydrogenation reaction, selectivity increase substantially.
Claims (10)
1. a C 2 fraction selective hydrogenation method, adopt the front-end hydrogenation process of predepropanization, undertaken selecting hydrogenation by ethylene unit enters fixed bed reactors from the tower top effluent of predepropanization tower, to remove alkynes therein and alkadienes, it is characterized in that equipped with Pd-Ag series catalysts in adiabatic reactor reactor, Pd-Ag series catalysts refers to employing Al2O3Being carrier, with the quality of catalyst for 100%, wherein Pd content is 0.015～0.050%；Ag content is 0.030～0.20%, and the specific surface area of catalyst is 1～20m2/ g, pore volume is 0.15～0.50ml/g；Catalyst, in preparation process, is combined with hydroxyl dipyridyl derivatives by alumina series carrier, and hydroxyl dipyridyl derivatives forms metal complex with active component；Reaction condition is: adiabatic reactor reactor inlet temperature 45～100 DEG C, reaction pressure 3.5～4.5MPa, gas space velocity 3500～25000h-1。
2. selection method of hydrotreating according to claim 1, it is characterized in that catalyst preparation process, at least including: loaded to by hydroxyl dipyridyl derivatives on alumina series carrier, the cation of the hydroxyl unnecessary again through hydroxyl dipyridyl derivatives and/or nitrilo and Pd, Ag forms complex ion.
3. selection method of hydrotreating according to claim 1, it is characterised in that hydroxyl dipyridyl derivatives is hydroxyl 2,2 ,-dipyridyl derivatives or hydroxyl 3,3 ,-dipyridyl derivatives, it is preferred to hydroxyl 2,2 ,-dipyridyl derivatives.
4. selection method of hydrotreating according to claim 1, it is characterised in that the acquisition of catalyst comprises the steps: the organic solution with hydroxyl dipyridyl derivatives, impregnates Al2O3It is carrier, obtains hydroxyl-bipyridyl/Al after drying2O3Precursor, the mixed-cation solution impregnation hydroxyl-bipyridyl/Al of preparation Pd, Ag2O3Precursor, dry at 60 DEG C～150 DEG C, obtain PdAg-hydroxyl-bipyridyl/Al2O3Precursor；At 300～600 DEG C of roasting temperature 2～12h, obtain required catalyst.
5. selection method of hydrotreating according to claim 1, it is characterised in that Al2O3Be carrier it is Al2O3Or mainly contain Al2O3,Wherein also doped with other hopcalite, other oxide is titanium oxide, magnesium oxide and/or calcium oxide；Described Al2O3For θ, α or its mixing crystal formation.
6. selection method of hydrotreating according to claim 4, it is characterised in that the preparation process of catalyst includes:
A. hydroxyl-bipyridyl/Al2O3The preparation of precursor
By the organic solution of hydroxyl dipyridyl derivatives and Al2O3It is carrier mixing, at 20 DEG C～60 DEG C temperature, reacts 2～24h, take out solid particle, dry at 60 DEG C～150 DEG C, obtain hydroxyl-bipyridyl/Al2O3Precursor；
B.PdAg-hydroxyl-bipyridyl/Al2O3The preparation of precursor
The mixed-cation solution of preparation Pd, Ag, with step A gained hydroxyl-bipyridyl/Al at 30 DEG C～100 DEG C temperature2O3Precursor reaction 2～24h, takes out solid particle, dry at 60 DEG C～150 DEG C, obtains PdAg-hydroxyl-bipyridyl/Al2O3Precursor；
C. the preparation of catalyst
PdAg-hydroxyl-bipyridyl/Al prepared by step B2O3Precursor is at 300～600 DEG C of roasting temperature 2～12h so that PdAg-hydroxyl-bipyridyl/Al2O3Precursor is changed into corresponding metal composite oxide, obtains catalyst.
7. selection method of hydrotreating according to claim 6, it is characterised in that in step A, hydroxyl-bipyridyl is 1～100: 1 with the ratio of the molal quantity of (Pd+Ag).
8. selection method of hydrotreating according to claim 6, it is characterised in that in stepb, the mixed solution that mixed-cation solution is Palladous nitrate. and silver nitrate of Pd, Ag.
9. selection method of hydrotreating according to claim 6, it is characterised in that in stepb, the ratio of the molal quantity of Ag and the molal quantity of Pd is 0.4～5: 1.
10. selection method of hydrotreating according to claim 6, it is characterised in that in stepb, the mixed-cation solution ph regulating Pd, Ag is 2.0～4.0.
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