CN104250185B - A kind of preparation method of low-carbon alkene - Google Patents
A kind of preparation method of low-carbon alkene Download PDFInfo
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- CN104250185B CN104250185B CN201310268977.7A CN201310268977A CN104250185B CN 104250185 B CN104250185 B CN 104250185B CN 201310268977 A CN201310268977 A CN 201310268977A CN 104250185 B CN104250185 B CN 104250185B
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- C—CHEMISTRY; METALLURGY
- C07—ORGANIC CHEMISTRY
- C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
- C07C5/00—Preparation of hydrocarbons from hydrocarbons containing the same number of carbon atoms
- C07C5/22—Preparation of hydrocarbons from hydrocarbons containing the same number of carbon atoms by isomerisation
- C07C5/27—Rearrangement of carbon atoms in the hydrocarbon skeleton
- C07C5/2702—Catalytic processes not covered by C07C5/2732 - C07C5/31; Catalytic processes covered by both C07C5/2732 and C07C5/277 simultaneously
- C07C5/2708—Catalytic processes not covered by C07C5/2732 - C07C5/31; Catalytic processes covered by both C07C5/2732 and C07C5/277 simultaneously with crystalline alumino-silicates, e.g. molecular sieves
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- C—CHEMISTRY; METALLURGY
- C07—ORGANIC CHEMISTRY
- C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
- C07C4/00—Preparation of hydrocarbons from hydrocarbons containing a larger number of carbon atoms
- C07C4/02—Preparation of hydrocarbons from hydrocarbons containing a larger number of carbon atoms by cracking a single hydrocarbon or a mixture of individually defined hydrocarbons or a normally gaseous hydrocarbon fraction
- C07C4/06—Catalytic processes
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- C—CHEMISTRY; METALLURGY
- C07—ORGANIC CHEMISTRY
- C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
- C07C2529/00—Catalysts comprising molecular sieves
- C07C2529/04—Catalysts comprising molecular sieves having base-exchange properties, e.g. crystalline zeolites, pillared clays
- C07C2529/06—Crystalline aluminosilicate zeolites; Isomorphous compounds thereof
- C07C2529/08—Crystalline aluminosilicate zeolites; Isomorphous compounds thereof of the faujasite type, e.g. type X or Y
- C07C2529/10—Crystalline aluminosilicate zeolites; Isomorphous compounds thereof of the faujasite type, e.g. type X or Y containing iron group metals, noble metals or copper
- C07C2529/12—Noble metals
Abstract
The invention discloses a kind of preparation method of low-carbon alkene, the method comprises the following steps: (1) isolates the first component and second component from liquefied petroleum gas (LPG), described first component is n-butene, Trimethylmethane or the mixture of the two, and described second component is the mixture of normal butane or normal butane and more than C5 component; (2) under the existence of isomerization catalyst, described second component is carried out isomerization reaction, at least part of normal butane isomerization is made to become Trimethylmethane, and three components and Four composition is isolated from the isomerization product obtained, described three components is below C3 component, and described Four composition is Trimethylmethane; (3) described first component, three components and Four composition are carried out steam cracking reaction.Adopt method provided by the invention can obtain higher yield of light olefins, thus improve utilization ratio and the Economic Value Added of liquefied petroleum gas (LPG).
Description
Technical field
The present invention relates to a kind of preparation method of low-carbon alkene.
Background technology
Along with the maximization of petroleum chemical enterprise's production equipment scale, the processing power of China's single cover oil refining apparatus is more than 1,000 ten thousand tons/year, and the throughput of ethylene unit supporting with it also reaches 80-120 ten thousand tons/year.Divinyl in the hybrid C 4 component that China's oil refining and ethylene unit are produced produces high purity butylene diene by extracting rectifying, iso-butylene generates methyl tertiary butyl ether (MTBE) by etherification reaction, and remaining butane and butylene are mainly for the production of liquefied petroleum gas (LPG) (being called for short LPG).At present, the output of the liquefied petroleum gas (LPG) that oil refining and ethylene unit are produced improves year by year, and annual production is more than 1,000 ten thousand tons.
Main containing C4 component in described liquefied petroleum gas (LPG), also may contain a small amount of below C3 component and/or more than C5 component.Wherein, below C3 component is mainly containing propane.C4 component, also may containing a small amount of iso-butylene and 1,3-micro-dibutene mainly containing Trimethylmethane, normal butane, n-butene.The component of more than C5 is mainly containing pentane, Benzene and Toluene.In the liquefied petroleum gas (LPG) of different sources, the content of said components may also exist larger difference.
At present, the liquefied petroleum gas (LPG) of petrochemical enterprise in China by-product is mainly used in the production of civil LPG, only have and produce gasoline and aromatic hydrocarbons for alkylation and aromizing on a small quantity, comprehensive utilization ratio is lower than 15%, well below the U.S., Japan and West Europe more than 50% utilize level, cause the economic value added of liquefied petroleum gas (LPG) resource low.And constantly increase along with the Sweet natural gas consumption of clean domestic fuel, the dim future that liquefied petroleum gas (LPG) uses as fuel.Therefore, make full use of liquefied petroleum gas (LPG) resource, improve its comprehensive utilization ratio and economic value added and become one of important channel of the economic benefit improving Petrochemical Enterprises.
Summary of the invention
The object of the invention is the defect that liquefied petroleum gas (LPG) utilization ratio and Economic Value Added in order to overcome prior art is low, and a kind of method adopting liquefied petroleum gas (LPG) to prepare low-carbon alkene is provided, adopt the method can obtain higher yield of light olefins.
The invention provides a kind of preparation method of low-carbon alkene, the method comprises the following steps:
(1) from liquefied petroleum gas (LPG), isolate the first component and second component, described first component is n-butene, Trimethylmethane or the mixture of the two, and described second component is the mixture of normal butane or normal butane and more than C5 component;
(2) under the existence of isomerization catalyst, described second component is carried out isomerization reaction, at least part of normal butane isomerization is made to become Trimethylmethane, and three components and Four composition is isolated from the isomerization product obtained, described three components is below C3 component, and described Four composition is Trimethylmethane;
(3) described first component, three components and Four composition are carried out steam cracking reaction.
As can be seen from the result of embodiment, adopt method of the present invention that the yield of the ethene obtained can be made to reach more than 17.72%, the yield of propylene reaches more than 15.66%, the yield of iso-butylene reaches more than 5.41%, the yield of divinyl reaches more than 1.64%, and the total recovery of low-carbon alkene reaches more than 51.39%.As can be seen here, adopt method provided by the invention can obtain higher yield of light olefins, thus improve utilization ratio and the Economic Value Added of liquefied petroleum gas (LPG).
Other features and advantages of the present invention are described in detail in embodiment part subsequently.
Embodiment
Below the specific embodiment of the present invention is described in detail.Should be understood that, embodiment described herein, only for instruction and explanation of the present invention, is not limited to the present invention.
The preparation method of low-carbon alkene provided by the invention comprises the following steps:
(1) from liquefied petroleum gas (LPG), isolate the first component and second component, described first component is n-butene, Trimethylmethane or the mixture of the two, and described second component is the mixture of normal butane or normal butane and more than C5 component;
(2) under the existence of isomerization catalyst, described second component is carried out isomerization reaction, at least part of normal butane isomerization is made to become Trimethylmethane, and three components and Four composition is isolated from the isomerization product obtained, described three components is below C3 component, and described Four composition is Trimethylmethane;
(3) described first component, three components and Four composition are carried out steam cracking reaction.
The component of described liquefied petroleum gas (LPG) is known to the skilled person, as a rule, main containing C4 component in described liquefied petroleum gas (LPG), also may contain a small amount of below C3 component and/or more than C5 component.Wherein, below C3 component, in addition may containing a small amount of hydrogen, methane and C2 component mainly containing propane.C4 component, in addition may containing a small amount of iso-butylene and micro-divinyl mainly containing normal butane, Trimethylmethane, n-butene.Wherein, n-butene comprises 1-butylene and 2-butylene, and 2-butylene comprises maleic and anti-butylene.More than C5 component is mainly pentane.According to the difference in source, may there is larger difference in the content of liquefied petroleum gas (LPG) said components.
Be specially adapted in described liquefied petroleum gas (LPG) of the present invention at least containing Trimethylmethane, normal butane and n-butene, and with the total content of described liquefied petroleum gas (LPG) for benchmark, the content of described Trimethylmethane can be 5-70mol%, the content of described normal butane can be 5-70mol%, and the content of described n-butene can be 0.1-80mol%; Under preferable case, with the total content of described liquefied petroleum gas (LPG) for benchmark, the content of described Trimethylmethane is 8-55mol%, and the content of described normal butane is 10-60mol%, and the content of described n-butene is 0.3-60mol%.Described butylene comprises 1-butylene and 2-butylene (comprising n-butene and anti-butylene).In addition, the present invention's liquefied petroleum gas (LPG) used also may contain 1 of below C3 component, more than C5 component, a small amount of iso-butylene and trace, 3-divinyl, with the total content of described liquefied petroleum gas (LPG) for benchmark, the content of described below C3 component can be 5-60mol%, and the content of described more than C5 component can be 0.3-3mol%, and the content of described iso-butylene can be 0.1-0.5mol%, the content of described 1,3-butadiene can be 0.01-0.1mol%.
The present invention is not particularly limited the method described first component and second component separated from described liquefied petroleum gas (LPG), such as, can adopt conventional distillation, extracting rectifying, fractionation by adsorption with in chemical separation method any one or to be multiplely separated.
According to a kind of embodiment of the present invention, when containing below C3 component in described liquefied petroleum gas (LPG), Trimethylmethane, normal butane, 1-butylene, iso-butylene, when 2-butylene (comprising maleic and anti-butylene) and more than C5 component, first be separated below C3 component and more than C4 Component seperation by conventional distillation, and more than the C4 component obtained is carried out conventional distillation separation, obtain the mixture of Trimethylmethane and 1-butylene and iso-butylene and the mixture of normal butane and 2-butylene and more than C5 component, again Trimethylmethane is carried out conventional distillation with 1-butylene and the mixture of iso-butylene and be separated the mixture and Trimethylmethane that obtain 1-butylene and iso-butylene, normal butane and 2-butylene and more than C5 component mixture are carried out conventional distillation and is separated the mixture and more than C5 component that obtain normal butane and 2-butylene.Due to 1-butylene and iso-butylene boiling point close, normal butane and 2-butylene boiling point close, use conventional distillation be separated be difficult to they are separated, also need to be separated with C 4 fraction fractionation and/or extraction fractional distillation further.
Described C 4 fraction fractionation can be under etherification reaction condition, the mixture of 1-butylene and iso-butylene and methyl alcohol are reacted, make isobutene conversion wherein be methyl tertiary butyl ether (MTBE), and then etherification product is carried out conventional distillation separation, obtain 1-butylene.
Extraction fractional distillation is the principle that utilizes the alkene of C4 and alkane relative volatility in extraction solvent to differ greatly and realizes being separated of alkane and alkene.Extraction smart process in solvent used usually can be in morpholine, N-Methyl pyrrolidone (NMP) and dimethyl formamide (DMF) any one or multiple.At present, extraction fractional distillation can be such as Japanese auspicious father-in-law's extraction fractional distillation or German Krupp-cooper that method (see DE3532289A1).
Particularly, the auspicious father-in-law's extraction fractional distillation of Japan can use DMF and/or NMP as solvent, the extracting system adopted generally includes two extracting rectifying devices and two rectifying tower, and each extracting rectifying device is made up of an extractive distillation column and a solvent recovery tower.The product obtained by first extracting rectifying device removing alkane, and is isolated 2-butylene at the first rectifying tower by C4 component, isolates 1-butylene at Second distillation column.In addition, the second extracting rectifying device is to isolate 1,3-butadiene.Therefore, if not containing 1,3-butadiene in C4 component to be separated, then the second extracting rectifying device can omit.The processing parameter of each extracting rectifying device and rectifying tower is set to as well known to those skilled in the art above, will repeat no more at this.
Germany's your method of Krupp-cooper take n-butene as target product, and raw material is C4 component after etherificate or through etherificate and precise distillation isolates the C4 component after 1-butylene and Trimethylmethane, the solvent adopted is anhydrous morpholine.Particularly, being introduced by C 4 fraction fills in the extraction solvent distillation tower of solvent, aliphatic fraction flows out from extraction solvent overhead, and the extraction liquid containing alkene goes out from extraction solvent distillation tower tower bottom flow, and the described extraction liquid containing alkene is obtained olefin component after recycling design in solvent recovery tower.The processing parameter of above extraction solvent distillation tower and solvent recovery tower is set to as well known to those skilled in the art, will repeat no more at this.
It should be noted that, in actual production process, in order to save the cost be separated further, being separated from liquefied petroleum gas (LPG) in the first component, three components and the Four composition obtained and may containing a small amount of impurity, as long as make the content of target separated product be greater than 95 % by weight.Such as, in embodiment 1, in C4 tower top material, the flow of Trimethylmethane is 17.56kg/h, accounts for 98.65 % by weight of C4 tower top material, now, this material directly can be carried out steam cracking as the raw material containing Trimethylmethane, and without the need to being separated further.In like manner, in embodiment 1, in C5 column overhead material, the flow of normal butane is 25.97kg/h, account for 98.45 % by weight of depentanizer tower top material, now, this material is directly carried out isomerization reaction as the raw material containing normal butane, and without the need to being separated further.
According to the present invention, in step (1), when the C5 component concentration in described liquefied petroleum gas (LPG) is lower, time such as not higher than 3mol%, step (1) can isolate the mixture of normal butane and more than C5 component from liquefied petroleum gas (LPG), and do not need further more than C5 component to be separated from normal butane, the normal butane then step (1) obtained and the mixture of more than C5 component directly carry out isomerization reaction.And when the content of more than the C5 component in described liquefied petroleum gas (LPG) is higher, time such as higher than 3mol%, step (1) needs the mixture first isolating normal butane and more than C5 component from liquefied petroleum gas (LPG) usually, again more than C5 component is separated from normal butane, and then normal butane is carried out isomerization reaction.
According to the present invention, as long as although the condition of described isomerization reaction can make at least part of normal butane be converted into Trimethylmethane, but in order to improve the yield of low-carbon alkene more significantly, the condition optimization of described isomerization reaction makes at least 8%, more preferably makes the normal butane isomerization of 25-70% become Trimethylmethane.In addition, described second component exists with the form of gas under lower pressure (as 0.01-0.5MPa), and exists in fluid form under higher pressure (as 1-8MPa).Correspondingly, in isomerization reaction, described second component can be reacted with the form of gas at lower pressures, also can react in fluid form at a higher pressure.Particularly, the condition of described isomerization reaction comprises: temperature of reaction can be 100-600 DEG C, is preferably 200-450 DEG C; Hydrogen hydrocarbon mol ratio can be 0-100, is preferably 0-10; For gas-phase reaction, reaction pressure can be 0.01-0.5MPa, and be preferably 0.05-0.5MPa, during gas, volume space velocity GHSV can be 100-1000h
-1, be preferably 300-800h
-1; For liquid phase reaction, reaction pressure can be 1-10MPa, preferred 2-6MPa, and during liquid, mass space velocity can be 0.05-20h
-1, be preferably 0.5-5h
-1.
In the present invention, during described liquid, mass space velocity refers to the quality of the catalyzer of unit mass treatment solution phase reaction per hour thing.During described gas, volume space velocity refers to the volume of the catalyzer of unit volume process vapor-phase reactant per hour.Described pressure all refers to gauge pressure.
The consumption of the present invention to described isomerization catalyst is not particularly limited, can come reasonably to select according to the amount of normal butane in described second component, as a rule, with the normal butane in the described second component of 100 weight parts for benchmark, the consumption of described isomerization catalyst can be 0.05-20 weight part.
According to the present invention, described isomerization catalyst can be the existing various catalyzer that normal butane can be made to be converted into Trimethylmethane, and as a rule, described isomerization catalyst comprises carrier and the active ingredient of load on carrier.Wherein, described carrier can be heat-resistant inorganic oxide and/or molecular sieve.Described heat-resistant inorganic oxide can be such as one or more in magnesium oxide, aluminum oxide, silicon oxide etc.Described molecular sieves is as being one or more in Y zeolite, β zeolite, mordenite, SAPO Series Molecules sieve, ZSM Series Molecules sieve, MCM Series Molecules sieve etc.Described active ingredient can be such as one or more in IVB race metal, group VIII metal and group vib metal.Described IVB race metal can be such as at least one in titanium (Ti), zirconium (Zr) and hafnium (Hf).Described group VIII metal can be such as at least one in iron (Fe), cobalt (Co), nickel (Ni), ruthenium (Ru), rhodium (Rh), palladium (Pd), iridium (Ir) and platinum (Pt).Described group vib metal can be such as at least one in chromium (Cr), molybdenum (Mo) and tungsten (W).Particularly preferably in situation, described active ingredient is one or more in platinum (Pt), palladium (Pd), nickel (Ni), molybdenum (Mo), cobalt (Co) and tungsten (W).
In addition, the content of described carrier and active ingredient can be the routine selection of this area, and such as, with the gross weight of described isomerization catalyst for benchmark, the content of described carrier can be 80-99.99 % by weight, is preferably 98-99.9 % by weight; The content of described active ingredient can be 0.01-20 % by weight, is preferably 0.1-2 % by weight.
According to a kind of embodiment of the present invention, described isomerization catalyst prepares in accordance with the following methods: mixed with the pseudo-boehmite of 10 weight parts by the H β zeolite powder (purchased from Catalyst Factory, Nankai Univ) of 40 weight parts, and add the dilute nitric acid solution that 7 weight part concentration are 2 % by weight, grind to form wet feed, pinch into diameter and be about the spherical of 2mm, then first in vacuum drying oven at 80 DEG C dry 2h, then in retort furnace at 500 DEG C roasting 2h.Be cooled to room temperature 25 DEG C after roasting completes, grind to form the particle of 380-830 μm as support of the catalyst (hereinafter referred to as KBY carrier).By equi-volume impregnating at KBY supported on carriers noble metal active component platinum Pt, the charge capacity of platinum is 0.61 % by weight, through leaving standstill, dry and obtain isomerization catalyst Pt/KBY after 500 DEG C of roastings.
According to the present invention, as mentioned above, below C3 component and more than C4 component can be contained in described liquefied petroleum gas (LPG) simultaneously, also only can contain more than C4 component.When in described liquefied petroleum gas (LPG) simultaneously containing below C3 component and more than C4 component time, the preparation method of low-carbon alkene provided by the invention also comprises isolate below C3 component from liquefied petroleum gas (LPG), and described below C3 component is carried out steam cracking reaction.
According to the present invention, when described first component, three components, Four composition and below C3 component are carried out steam cracking reaction, said components can be carried out steam cracking reaction respectively; Also can carry out steam cracking reaction by after wherein several mixing, and carry out steam cracking reaction by after remaining mixing; Also steam cracking reaction is carried out together after said components can being mixed.
Method provided by the invention also comprises isolates ethene, propylene, iso-butylene and divinyl from steam cracking product.It should be noted that, described first component, three components, Four composition and below C3 component are carried out steam cracking reaction by the present invention, multiple split product may be obtained, now, first can isolate ethene, propylene, iso-butylene and divinyl again from the mixture obtained by after multiple split product mixing, also several split product can be separated respectively.
According to the present invention, described steam cracking reaction and being separated in cracker of split product are carried out.Described cracker comprises pyrolyzer and tripping device.Described pyrolyzer can be the pyrolyzer of preparing ethylene by steam cracking, propylene, iso-butylene and the divinyl that this area routine uses.Described pyrolyzer mainly comprises convection zone, radiation section, quenching boiler and gas burning system usually.In described pyrolyzer, respectively by cracking stock be steam heated to generation steam cracking reaction, generate containing the splitting gas of ethene, propylene, iso-butylene and divinyl.In the preferred case, described pyrolyzer is preferably tube cracking furnace.Described tube cracking furnace comprises convection zone, radiation section, quenching boiler and gas burning system, and cracking stock enters radiation section in convection zone; In radiation section, cracking stock be steam heated to generation steam cracking reaction, generate containing the splitting gas of ethene, propylene, iso-butylene and divinyl; Splitting gas out enters quenching boiler afterwards from radiation section, and in quenching boiler, splitting gas is cooled to 300-600 DEG C, to make splitting gas scission reaction not occur, reclaims heat simultaneously; Fuel system is used for providing heat to steam cracking reaction process.Described tripping device is used for hydrocarbon splitting gas being separated into different carbon number.As a rule, described tripping device mainly comprises: oil scrubber, water wash column, ice chest, compressor, demethanizing tower, deethanizing column, ethylene rectification tower, depropanizing tower, propylene rectification tower, debutanizing tower, C2 and C3 hydrogenation unit, C2 and C3 rectifying tower, methanation device and butadiene extraction unit.The implementation method of described tripping device has been conventionally known to one of skill in the art, does not repeat them here.
According to the present invention, when described steam cracking reaction carries out in pyrolyzer, in described steam cracking reaction process, the coil outlet temperature of described pyrolyzer is preferably 710-890 DEG C, is more preferably 750-830 DEG C; Water weight of oil, than being preferably 0.3-1, is more preferably 0.35-0.65.In addition, in described steam cracking reaction process, other Parameter Conditions of described pyrolyzer can processing condition conveniently be implemented, and are not particularly limited in the present invention.
Below will be described the present invention by embodiment.
In the following Examples and Comparative Examples, yield of light olefins is according to following formulae discovery:
Gross weight × 100% of the weight ÷ steam cracking reaction product of ethene in yield of ethene (% by weight)=steam cracking reaction product;
Gross weight × 100% of the weight ÷ steam cracking reaction product of propylene in propene yield (% by weight)=steam cracking reaction product;
Gross weight × 100% of the weight ÷ steam cracking reaction product of iso-butylene in iso-butylene yield (% by weight)=steam cracking reaction product;
Gross weight × 100% of the weight ÷ steam cracking reaction product of divinyl in butadiene yield (% by weight)=steam cracking reaction product;
Total recovery (% by weight)=yield of ethene+propene yield+iso-butylene yield+butadiene yield.
In following examples and comparative example, isomerization catalyst prepares in accordance with the following methods: mixed with the pseudo-boehmite of 10 weight parts by the H β zeolite powder (purchased from Catalyst Factory, Nankai Univ company) of 40 weight parts, and add the dilute nitric acid solution that 7 weight part concentration are 2 % by weight, grind to form wet feed, pinch into diameter and be about the spherical of 2mm, then first in vacuum drying oven at 80 DEG C dry 2h, then in retort furnace at 500 DEG C roasting 2h.Be cooled to room temperature 25 DEG C after roasting completes, grind to form the particle of diameter 380-830 μm as support of the catalyst (hereinafter referred to as KBY carrier).By equi-volume impregnating at KBY supported on carriers noble metal active component platinum Pt, platinum charge capacity is 0.61 % by weight, through leaving standstill, dry and obtain isomerization catalyst Pt/KBY after 500 DEG C of roastings.
In following examples and comparative example, the composition of the liquefied petroleum gas (LPG) LPG used is as shown in table 1:
Table 1
Embodiment 1
This embodiment is for illustration of the preparation method of low-carbon alkene provided by the invention.
(1) be separated:
Liquefied petroleum gas (LPG) LPG-1 is separated from the middle part introducing C3 tower of C3 tower with inlet amount 100kg/h, temperature 40 DEG C, pressure 11atm, the material that C3 column overhead obtains is below C3 component (cracking stock 1, wherein, the mass content of propane is 95.69%, the mass content of ethane is 2.75%, all the other are alkene), the material obtained at the bottom of tower is more than C4 component; More than C4 component introduced C4 tower from the middle part of C4 tower and be separated, C4 column overhead obtains the Trimethylmethane that mass content is 99%, obtains the mixture of normal butane and pentane at the bottom of tower; Introduced C5 tower from the middle part of C5 tower by C4 tower materials at bottom of tower and be separated, C5 column overhead obtains the normal butane that mass content is 98.45%.The parameter of C3 tower, C4 tower and C5 tower is arranged by table 2, and result is as shown in table 3.
Table 2
| Numbering | C3 tower | C4 tower | C5 tower |
| Number of theoretical plate | 35.0 | 99.0 | 30.0 |
| Tower top temperature, DEG C | 24.2 | 34.1 | 50.6 |
| Column bottom temperature, DEG C | 69.2 | 58.3 | 93.4 |
| Tower top pressure, atm | 10.0 | 4.5 | 5.0 |
| Tower bottom pressure, atm | 10.1 | 6.0 | 5.1 |
| Reflux ratio | 10.0 | 20.0 | 3.0 |
Table 3
(2) isomerization reaction:
Loaded by isomerization catalyst in the continuous micro-reactor of 15mL flowing-type fixed bed high pressure (purchased from Haian Oil Scientific Research Apparatus Co., Ltd., model is WYF-2 type high-temperature high-voltage reaction device, lower same), the loadings of isomerization catalyst is 6mL.Introduced continuously in this reaction unit by the normal butane that step (1) C5 column overhead obtains and react, controlling reaction conditions is: mol ratio 3.0, the liquid phase quality air speed 1.24h of pressure 2.0MPa, temperature 400 DEG C, hydrogen and hydrocarbon
-1, obtain isomerization product.Wherein, the transformation efficiency of normal butane is 65.5%, and the selectivity of Trimethylmethane is the selectivity of 55.6%, C1-C3 hydrocarbon mixture is 44.4%(C1:C2:C3=22:28:50).Because isomerization product mid-boiling point difference is larger, hydrocarbon mixture (the ethane: propane=36:64 obtaining ethane and propane can be separated by conventional distillation, weight ratio), Trimethylmethane, normal butane, the hydrocarbon mixture of ethane and propane and Trimethylmethane are used as cracking stock, and normal butane can return the raw material as isomerization reaction.
(3) steam cracking reaction:
The mixture of the Trimethylmethane that the cracking stock 1 step (1) obtained, step (1) and step (2) obtain, ethane that step (2) obtains and propane is introduced respectively in pyrolyzer and is carried out steam cracking reaction, obtains three kinds of steam cracking products.Wherein, the condition of steam cracking reaction is as shown in table 10 below.Isolate ethene, propylene, iso-butylene and divinyl after being mixed by three kinds of steam cracking products, and calculate the yield of ethene, propylene, iso-butylene and divinyl, result is as shown in table 11.
Embodiment 2
This embodiment is for illustration of the preparation method of low-carbon alkene provided by the invention.
(1) be separated:
Liquefied petroleum gas (LPG) LPG-2 is separated from the middle part introducing C3 tower of C3 tower with inlet amount 100kg/h, temperature 40 DEG C, pressure 11atm, the material that C3 column overhead obtains is below C3 component (cracking stock 2, wherein, the mass content of propane is 93.98%, the mass content of ethane is 5.91%, all the other are propylene and propine), the material obtained at the bottom of tower is more than C4 component; More than C4 component introduced C4 tower from the middle part of C4 tower and be separated, C4 column overhead obtains the Trimethylmethane that mass content is 99.65%, and in the material obtained at the bottom of tower, the mass content of normal butane is 91.12%, and the mass content of pentane is 3.96%, remaining as butylene.The parameter of C3 tower and C4 tower is arranged by table 4, and result is as shown in table 5.
Table 4
| Numbering | C3 tower | C4 tower |
| Number of theoretical plate | 35.0 | 99.0 |
| Tower top temperature, DEG C | 24.2 | 34.1 |
| Column bottom temperature, DEG C | 69.2 | 58.3 |
| Tower top pressure, atm | 10.0 | 4.5 |
| Tower bottom pressure, atm | 10.1 | 6.0 |
| Reflux ratio | 10.0 | 20.0 |
Table 5
(2) isomerization reaction:
Loaded by isomerization catalyst in the continuous micro-reactor of 15mL flowing-type fixed bed high pressure, the loadings of isomerization catalyst is 6mL.Introduced continuously in this reaction unit by the material obtained at the bottom of step (1) C4 tower tower and react, controlling reaction conditions is: mol ratio 3.0, the liquid phase quality air speed 1.24h of pressure 2.0MPa, temperature 400 DEG C, hydrogen and hydrocarbon
-1, obtain isomerization product.Wherein, the transformation efficiency of normal butane is 65.5%, and the selectivity of Trimethylmethane is the selectivity of 55.6%, C1-C3 hydrocarbon mixture is 44.4%(C1:C2:C3=22:28:50).Because isomerization product mid-boiling point difference is larger, hydrocarbon mixture (the ethane: propane=36:64 obtaining ethane and propane can be separated by conventional distillation, weight ratio), Trimethylmethane, normal butane, the hydrocarbon mixture of ethane and propane and Trimethylmethane are used as cracking stock, and normal butane can return the raw material as isomerization reaction.
(3) steam cracking reaction:
The mixture of the Trimethylmethane that the cracking stock 2 step (1) obtained, step (1) and step (2) obtain, ethane that step (2) obtains and propane is introduced respectively in pyrolyzer and is carried out steam cracking reaction, obtains three kinds of steam cracking products.Wherein, the condition of steam cracking reaction is as shown in table 10 below.Isolate ethene, propylene, iso-butylene and divinyl after being mixed by three kinds of steam cracking products, and calculate the yield of ethene, propylene, iso-butylene and divinyl, result is as shown in table 11.
Embodiment 3
This embodiment is for illustration of the preparation method of low-carbon alkene provided by the invention.
(1) be separated:
Be separated from the middle part introducing C4 tower of C3 tower with inlet amount 100kg/h, temperature 40 DEG C, pressure 11atm by liquefied petroleum gas (LPG) LPG-3, C4 column overhead obtains the Trimethylmethane that mass content is 98.87 % by weight, obtains the mixture of normal butane and 2-butylene at the bottom of tower.Then the material obtained at the bottom of C4 tower tower is separated by your method of German Krupp-cooper, the normal butane obtained and 2-butylene.The parameter of C4 tower is arranged by table 6, and result is as shown in table 7.
Table 6
| Numbering | C4 tower |
| Number of theoretical plate | 99.0 |
| Tower top temperature, DEG C | 34.1 |
| Column bottom temperature, DEG C | 57.7 |
| Tower top pressure, atm | 4.5 |
| Tower bottom pressure, atm | 6.0 |
| Reflux ratio | 20.0 |
Table 7
(2) isomerization reaction:
Loaded by isomerization catalyst in the continuous micro-reactor of 15mL flowing-type fixed bed high pressure, the loadings of isomerization catalyst is 6mL.Introduced continuously in this reaction unit by the normal butane that step (1) obtains and react, controlling reaction conditions is: mol ratio 3.0, the liquid phase quality air speed 1.24h of pressure 2.0MPa, temperature 400 DEG C, hydrogen and hydrocarbon
-1, obtain isomerization product.Wherein, the transformation efficiency of normal butane is 65.5%, and the selectivity of Trimethylmethane is the selectivity of 55.6%, C1-C3 hydrocarbon mixture is 44.4%(C1:C2:C3=22:28:50).Because isomerization product mid-boiling point difference is larger, hydrocarbon mixture (the ethane: propane=36:64 obtaining ethane and propane can be separated by conventional distillation, weight ratio), Trimethylmethane, normal butane, the hydrocarbon mixture of ethane and propane and Trimethylmethane are used as cracking stock, and normal butane can return the raw material as isomerization reaction.
(3) steam cracking reaction:
The mixture of the Trimethylmethane that 2-butylene step (1) obtained, step (1) and step (2) obtain, ethane that step (2) obtains and propane is introduced respectively in pyrolyzer and is carried out steam cracking reaction, obtains three kinds of steam cracking products.Wherein, the condition of steam cracking reaction is as shown in table 10 below.Isolate ethene, propylene, iso-butylene and divinyl after being mixed by three kinds of steam cracking products, and calculate the yield of ethene, propylene, iso-butylene and divinyl, result is as shown in table 11.
Embodiment 4
This embodiment is for illustration of the preparation method of low-carbon alkene provided by the invention.
(1) be separated:
Liquefied petroleum gas (LPG) LPG-4 is separated from the middle part introducing C3 tower of C3 tower with inlet amount 100kg/h, temperature 40 DEG C, pressure 11atm, the material that C3 column overhead obtains is below C3 component (cracking stock 3, wherein, the mass content of propane is 95.56%, remaining as propylene), the material obtained at the bottom of tower is more than C4 component, more than C4 component is introduced C4 tower from the middle part of C4 tower and is separated, C4 column overhead obtains the mixture of Trimethylmethane and 1-butylene (wherein, the mass content of Trimethylmethane is 21.21%, the mass content of 1-butylene is 78.28%), the mixture of normal butane and 2-butylene is obtained (wherein at the bottom of C4 tower tower, the mass content of normal butane is 53.4%, the mass content of 2-butylene is 44.97%), material C4 column overhead obtained is introduced butylene tower from the middle part of butylene tower and is separated, the material that butylene column overhead obtains is the mixture of Trimethylmethane and 1-butylene, wherein, the mass content of Trimethylmethane is 59.53%, the mass content of 1-butylene is 40.40%.Then the material obtained with butylene column overhead at the bottom of C4 tower tower is separated by your method of German Krupp-cooper, obtains normal butane, Trimethylmethane, 1-butylene and 2-butylene.Wherein, the parameter of C3 tower, C4 tower and butylene tower is arranged by table 8, and result is as shown in table 9.
Table 8
| Numbering | C3 tower | C4 tower | Butylene tower |
| Number of theoretical plate | 35.0 | 99.0 | 150.0 |
| Tower top temperature, DEG C | 26.8 | 38.2 | 31.99 |
| Column bottom temperature, DEG C | 76.0 | 58.1 | 39.31 |
| Tower top pressure, atm | 10.0 | 4.5 | 4.0 |
| Tower bottom pressure, atm | 10.1 | 6.0 | 4.5 |
| Reflux ratio | 20.0 | 20.0 | 20.0 |
Table 9
(2) isomerization reaction:
Loaded by isomerization catalyst in the continuous micro-reactor of 15mL flowing-type fixed bed high pressure, the loadings of isomerization catalyst is 6mL.Introduced continuously in this reaction unit by the normal butane that step (1) obtains and react, controlling reaction conditions is: mol ratio 3.0, the liquid phase quality air speed 1.24h of pressure 2.0MPa, temperature 400 DEG C, hydrogen and hydrocarbon
-1, obtain isomerization product.Wherein, the transformation efficiency of normal butane is 65.5%, and the selectivity of Trimethylmethane is the selectivity of 55.6%, C1-C3 hydrocarbon mixture is 44.4%(C1:C2:C3=22:28:50).Because isomerization product mid-boiling point difference is larger, hydrocarbon mixture (the ethane: propane=36:64 obtaining ethane and propane can be separated by conventional distillation, weight ratio), Trimethylmethane, normal butane, the hydrocarbon mixture of ethane and propane and Trimethylmethane are used as cracking stock, and normal butane can return the raw material as isomerization reaction.
(3) steam cracking reaction:
The mixture of the Trimethylmethane that the cracking stock 3 step (1) obtained, 1-butylene, 2 butylene, step (1) and step (2) obtain, ethane that step (2) obtains and propane is introduced respectively in pyrolyzer and is carried out steam cracking reaction, and will obtain isolating ethene, propylene, iso-butylene and divinyl after steam cracking product mixes.Wherein, the condition of steam cracking reaction is as shown in table 10 below, and result is as shown in table 11.
Embodiment 5
This embodiment is for illustration of the preparation method of low-carbon alkene provided by the invention.
(1) be separated:
Carry out according to the method for embodiment 1;
(2) isomerization reaction:
Carry out according to the method for embodiment 1, unlike, during liquid, mass space velocity is 1.5h
-1, temperature of reaction is 350 DEG C, obtain isomerization product, wherein, the transformation efficiency of normal butane is 22.4%, and the selectivity of Trimethylmethane is 45.5%; In isomerization product, the content of normal butane is 77.6 % by weight, and the content of Trimethylmethane is 10.2 % by weight, C
1-C
3the content of hydrocarbon mixture is 12.8 % by weight.
Because isomerization product mid-boiling point difference is larger, hydrocarbon mixture (the ethane: propane=36:64 obtaining ethane and propane can be separated by conventional distillation, weight ratio), Trimethylmethane, normal butane, the hydrocarbon mixture of ethane and propane and Trimethylmethane are used as cracking stock, and normal butane can return the raw material as isomerization reaction.
(3) steam cracking reaction:
Carry out according to the method for embodiment 1, the condition of steam cracking reaction is as shown in table 10, and result is as shown in table 11.
Comparative example 1
This comparative example is for illustration of the reference preparation method of low-carbon alkene.
Liquefied petroleum gas (LPG) LPG-1 is directly sent in pyrolyzer and carries out steam cracking reaction, obtain steam cracking product, then from steam cracking product, isolate ethene, propylene and iso-butylene.Wherein, the condition of steam cracking reaction is as shown in table 10 below, and result is as shown in table 11.
Comparative example 2
This comparative example is for illustration of the reference preparation method of low-carbon alkene.
Carry out according to the method for comparative example 1, unlike, described liquefied petroleum gas (LPG) LPG-1 liquefied petroleum gas (LPG) LPG-2 substitutes, and wherein, the condition of steam cracking reaction is as shown in table 10 below, and the result obtained is as shown in table 11.
Comparative example 3
This comparative example is for illustration of the reference preparation method of low-carbon alkene.
Carry out according to the method for comparative example 1, unlike, described liquefied petroleum gas (LPG) LPG-1 liquefied petroleum gas (LPG) LPG-3 substitutes, and wherein, the condition of steam cracking reaction is as shown in table 10 below, and the result obtained is as shown in table 11.
Comparative example 4
This comparative example is for illustration of the reference preparation method of low-carbon alkene.
Carry out according to the method for comparative example 1, unlike, described liquefied petroleum gas (LPG) LPG-1 liquefied petroleum gas (LPG) LPG-4 substitutes, and wherein, the condition of steam cracking reaction is as shown in table 10 below, and the result obtained is as shown in table 11.
Table 10
Note: in table 10, CBL-III type pyrolyzer and CBL-R type pyrolyzer are all purchased from China PetroChemical Corporation.
Table 11
As can be seen from the above results, adopt method provided by the invention can significantly improve the yield of low-carbon alkene, thus solve existing liquefied petroleum gas (LPG) utilization ratio and the low problem of Economic Value Added.
More than describe the preferred embodiment of the present invention in detail; but the present invention is not limited to the detail in above-mentioned embodiment, within the scope of technical conceive of the present invention; can carry out multiple simple variant to technical scheme of the present invention, these simple variant all belong to protection scope of the present invention.
It should be noted that in addition, each the concrete technical characteristic described in above-mentioned embodiment, in reconcilable situation, can be combined by any suitable mode.In order to avoid unnecessary repetition, the present invention illustrates no longer separately to various possible array mode.
In addition, also can carry out arbitrary combination between various different embodiment of the present invention, as long as it is without prejudice to thought of the present invention, it should be considered as content disclosed in this invention equally.
Claims (11)
1. a preparation method for low-carbon alkene, the method comprises the following steps:
(1) from liquefied petroleum gas (LPG), isolate the first component and second component, described first component is n-butene, Trimethylmethane or the mixture of the two, and described second component is the mixture of normal butane or normal butane and more than C5 component;
(2) under the existence of isomerization catalyst, described second component is carried out isomerization reaction, at least part of normal butane isomerization is made to become Trimethylmethane, and three components and Four composition is isolated from the isomerization product obtained, described three components is below C3 component, and described Four composition is Trimethylmethane;
(3) described first component, three components and Four composition are carried out steam cracking reaction.
2. method according to claim 1, wherein, at least containing Trimethylmethane, normal butane and n-butene in described liquefied petroleum gas (LPG), and with the total content of described liquefied petroleum gas (LPG) for benchmark, the content of described Trimethylmethane is 5-70mol%, the content of described normal butane is 5-70mol%, and the content of described n-butene is 0.1-80mol%.
3. method according to claim 1 and 2, wherein, the condition of described isomerization reaction makes the normal butane isomerization of at least 8% become Trimethylmethane.
4. method according to claim 3, wherein, the condition of described isomerization reaction makes the normal butane isomerization of 25-70% become Trimethylmethane.
5. method according to claim 3, wherein, the condition of described isomerization reaction comprises: temperature of reaction is 100-600 DEG C, and hydrogen hydrocarbon mol ratio is 0-100, and for gas-phase reaction, reaction pressure is 0.01-0.5MPa, and during gas, volume space velocity is 100-1000h
-1; For liquid phase reaction, reaction pressure is 1-10MPa, and during liquid, mass space velocity is 0.05-20h
-1.
6. the method according to claim 1,2 or 5, wherein, described isomerization catalyst comprises carrier and the active ingredient of load on carrier, described carrier is heat-resistant inorganic oxide and/or molecular sieve, and described active ingredient is one or more in IVB race metal, group VIII metal and group vib metal.
7. method according to claim 6, wherein, described active ingredient is one or more in platinum, palladium, nickel, molybdenum, cobalt and tungsten.
8. the method according to claim 1,2 or 5, wherein, also containing below C3 component in described liquefied petroleum gas (LPG), the method also comprises isolates below C3 component from liquefied petroleum gas (LPG), and described below C3 component is carried out steam cracking reaction.
9. the method according to claim 1,2 or 5, wherein, described steam cracking reaction carries out in pyrolyzer, and in described steam cracking reaction process, the coil outlet temperature of described pyrolyzer is 710-890 DEG C, and water weight of oil is than being 0.3-1.
10. method according to claim 9, wherein, described pyrolyzer is tube cracking furnace.
11. methods according to claim 1,2 or 5, wherein, the method also comprises isolates ethene, propylene, iso-butylene and divinyl from steam cracking product.
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