CN106669718B

CN106669718B - A kind of synthesis gas alkene catalyst and its preparation method and application

Info

Publication number: CN106669718B
Application number: CN201510750236.1A
Authority: CN
Inventors: 李�杰; 张信伟; 张舒冬; 孙晓丹; 尹泽群; 刘全杰
Original assignee: China Petroleum and Chemical Corp; Sinopec Fushun Research Institute of Petroleum and Petrochemicals
Current assignee: China Petroleum and Chemical Corp; Sinopec Fushun Research Institute of Petroleum and Petrochemicals
Priority date: 2015-11-09
Filing date: 2015-11-09
Publication date: 2018-01-16
Anticipated expiration: 2035-11-09
Also published as: CN106669718A

Abstract

The present invention discloses a kind of preparation method of preparation of low carbon olefines by synthetic gas catalyst, comprises the following steps：（1）The isometric saturation of alumina support impregnates the organic compounds containing nitrogen aqueous solution, and it is the 30 60% of alumina support saturated absorption amount of solution to be dried after dipping to the adsorbance of the organic compounds containing nitrogen aqueous solution；（2）Prepare the mixed aqueous solution of nickel salt and gallium salt, step（1）The modified aluminium oxide supports of preparation use the above-mentioned mixed aqueous solution of unsaturated impregnation；（3）Using fountain solution impregnation steps of the unsaturated infusion process containing adsorbent（2）Carrier after roasting；（4）Step（3）Carrier impregnation containing adsorbent contains the solution of active metal iron, the impregnating metal auxiliary agent, then preparation of low carbon olefines by synthetic gas catalyst is made after drying, roasting again after drying, roasting.The catalyst has the characteristics of long-term operation activity stability is high, is advantageous to commercial Application and popularization.

Description

A kind of synthesis gas alkene catalyst and its preparation method and application

Technical field

The present invention relates to a kind of synthesis gas alkene catalyst and preparation method thereof, it is steady to relate in particular to a kind of high activity Qualitative load-type iron-based preparation of low carbon olefines by synthetic gas catalyst and preparation method thereof.

Background technology

The low-carbon alkenes such as ethene, propylene are important basic organic chemical industry raw materials, with the development of chemical industry, its demand Amount is more and more big.So far, the approach of the low-carbon alkene such as preparing ethylene, propylene is mainly by light oil cracking process, with complete The increasingly depleted of petroleum resources in the range of ball, following energy resource structure certainly will shift.Compared with petroleum resources, coal and natural Gas resource relative abundance, develop the low-carbon alkene production technology based on coal and natural gas and have great importance.From synthesis gas （It can be converted to by natural gas and coal）The exploitation of direct preparing ethylene, propylene technology, can not only reduce to petroleum resources according to Rely, and to the chemical industrial expansion important in inhibiting in some rich gas oil starvations area.

CN1065026A discloses a kind of preparation of ethylene by use of synthetic gas method, and the preparation method for being related to catalyst is chemical precipitation Method, mechanical mixing, employ noble metal or rare metal, such as the kind chemistry of niobium, gallium, praseodymium, scandium, indium, cerium, lanthanum, ytterbium etc. more than ten Element, ethylene selectivity 65%-94%, but CO conversion ratios are very low, only 10%, 12% and 15% or so, and CO is recycled and certainly will brought The consumption of the energy, and catalyst cost is high.CN01144691.9 discloses the nano-catalytic of a kind of preparation of ethylene by use of synthetic gas, propylene Agent and preparation method thereof, the combination technique of laser pyrolysis processes combination solid phase reaction is used to be prepared for Fe₃Fe base nanometers based on C Catalyst is applied and preparing low-carbon olefin, and achieves certain effect, but due to needing practical laser technology, makes Preparation technology is comparatively laborious, and raw material uses Fe (CO)₅, the cost of catalyst is higher, and industrialization is difficult.CN03109585.2 is public Opened it is a kind of be used for preparation of ethylene by use of synthetic gas, propylene, iron/activated-carbon catalyst of butene reaction, using activated carbon as carrier, Fe As activated centre, successfully Fe is loaded on the activated carbon using vacuum impregnation technology, Fe and auxiliary agent is highly dispersed at On activated carbon, so as to improve catalytic effect, and the cost of catalyst is greatly reduced.And catalyst is in the condition without feedstock circulation Lower CO conversion ratios are up to 96-99%, and CH compounds selectivity is up to 69.5% in gas-phase product, and wherein ethene, propylene, butylene are in CHization Selectivity in compound is up to more than 68%.But activated carbon is as catalyst carrier not only bad mechanical strength but also shaping of catalyst Difficulty, the service life and stability of catalyst are influenceed, is unfavorable for commercial Application.

CN102441383A, CN101940958A, CN102441400A, CN102441384A are respectively adopted nitrogenous organic Compound solution, acid solution, the cushioning liquid of ammonium salt-containing, the mode such as hydro-thermal process impregnation is carried out to silica-gel carrier, Prepare Fe base silica gel supported synthesis gas and directly prepare light olefins catalyst, reduce Fe and SiO₂Strong phase between carrier Interaction.But the activity that above-mentioned Fe bases silica gel supported synthesis gas directly prepares the long-term operation of light olefins catalyst is steady It is qualitative still to need further to be improved.

The content of the invention

In view of the shortcomings of the prior art, the present invention provides a kind of low using aluminum oxide as the iron-based support type synthesis gas system of carrier Carbene hydrocarbon catalyst and preparation method thereof, the catalyst have the characteristics of long-term operation activity stability is high, are advantageous to industry Using and promote.

A kind of preparation method of preparation of low carbon olefines by synthetic gas catalyst, comprises the following steps：

（1）The alumina support isometric saturation dipping organic compounds containing nitrogen aqueous solution, immediately at 95-110 DEG C after dipping Lower dry 0.5-1h, it is alumina support saturated absorption amount of solution to dry to the adsorbance of the organic compounds containing nitrogen aqueous solution 30-60%, modified aluminium oxide supports are then made after aging, drying, roasting；

（2）Prepare the mixed aqueous solution of nickel salt and gallium salt, step（1）The modified aluminium oxide supports of preparation are soaked using unsaturated Stain method impregnates above-mentioned mixed aqueous solution, dries after being calcined 1h-10h at 700 DEG C ~ 1000 DEG C, is preferably roasted at 800 DEG C ~ 900 DEG C Burn 2h-8h；

（3）Using fountain solution impregnation steps of the unsaturated infusion process containing adsorbent（2）Carrier after roasting, wherein institute The adsorbent stated is the organic amine that carbon number is 2~15, and the addition of described adsorbent accounts for step（2）Vehicle weight after roasting 1% ~ 10%；

（4）Step（3）Carrier impregnation containing adsorbent contains the solution of active metal iron, is impregnated again after drying, roasting Metal promoter, then preparation of low carbon olefines by synthetic gas catalyst is made after drying, roasting.

The inventive method step（1）Organic compounds containing nitrogen can be selected from ethanol in the middle organic compounds containing nitrogen aqueous solution One or more in amine, diethanol amine, triethanolamine and pyridine etc..Nitrogenous organic compound in the organic compounds containing nitrogen aqueous solution The weight concentration of thing is 1%-35%, preferably 5%-20%.Aging temperature is 50-95 DEG C, and preferably 60 ~ 80 DEG C, ageing time is 0.5-10h, preferably 2-5h.Drying temperature is 90-150 DEG C, drying time 0.5-36h after aging, preferably at 100-120 DEG C Dry 8-24h.Roasting is calcined 2-15 hours at 280-500 DEG C, and 3-5 hours are calcined preferably at 300-450 DEG C.

The inventive method, step（2）Middle nickel salt is the one or more in nickel chloride, nickel nitrate or nickel sulfate, and gallium salt is One or more in gallium nitrate, gallium chloride, gallium sulfate.The concentration of nickel ion is 0.1-5mol/L in mixed aqueous solution, gallium from The molar concentration of son is two times of nickel ion molar concentration.

The inventive method, step（2）Pickup is the 5-60%, preferably 20-50% of alumina support saturated absorption amount of solution. Dip time is 1-5h, and dipping temperature is 40-60 DEG C.Drying temperature is 80-150 DEG C after dipping, drying time 2-15h.

The inventive method, step（2）Middle alumina support can use existing commercial goods, can also be by existing method system It is standby.Support shapes can be spherical, bar shaped, piece type.Using spherical and bar shaped to be best.

The inventive method, step（3）Middle organic amine includes one kind in fatty amine, hydramine, acid amides, aliphatic cyclic amine or aromatic amine It is or several.Specifically include monoethyl amine, diethylamine, triethylamine, ethylenediamine, hexamethylene diamine, tert-butylamine, monoethanolamine, diethanol amine, three One kind in monoethanolamine, dimethylformamide, propionamide, butyramide, pyridine, morphine, aniline, diphenylamines, naphthalidine, dinaphthylamine Or several, the one or more preferably in diethylamine, triethylamine, morphine.

Step of the present invention（3）In, the fountain solution containing adsorbent is impregnated, is impregnated using unsaturation, preferably with unsaturation Spray, wherein the volume ratio of the dip amount and carrier saturated absorption amount of solution used in unsaturated dipping is 0.05 ~ 0.4.Dipping contains After having the fountain solution of adsorbent, can be dried under the decomposition temperature no more than selected adsorbent, can also direct impregnation contain work Property metallic iron solution, wherein drying temperature is generally 60 DEG C~150 DEG C, and 80 DEG C~120 DEG C are preferably, drying time 0.5h~ 20h, preferably 1h~6h.When spraying the fountain solution containing adsorbent, the good shower nozzle of atomizing effect should be selected, solution is uniformly divided It is scattered on alumina support.After fountain solution dipping of the dipping containing adsorbent terminates, next step can be directly carried out, may also pass through Health carries out next step again, and conditioned time is 0.5~8h.

The inventive method, step（4）Middle auxiliary agent is K and Mn.Fe is with helping in the preparation of low carbon olefines by synthetic gas catalyst of preparation Agent K and Mn mass ratio is respectively（65~75）：（0.5~5）：（23~34）.Active component Fe and metal promoter K, Mn pass through dipping Method is supported on carrier, generally use incipient impregnation.Dipping method is known to technical staff.With containing active metal or helping After the solution impregnating carrier of agent, it is necessary to by drying and being calcined.Active metal solution or compounding agent solution preparation method are technology people Known to member, its solution concentration can be adjusted by the dosage of each compound, be contained so as to prepare specified activity component and auxiliary agent The catalyst of amount.The raw material of required active component and auxiliary agent is generally the compound of the types such as salt, oxide or acid, such as source of iron The one or more being generally from ferric nitrate, iron chloride, ferric sulfate, potassium resource in potassium nitrate, potassium carbonate, potassium chloride one Kind is several, and manganese source is generally from manganese nitrate or manganese chloride.

The inventive method, step（4）In add 2-15% in the solution containing active metal iron, preferably 5-10% is with quality The ammonium citrate of meter.The decentralization of active component can be improved using the iron salt solutions containing ammonium citrate are added, is prepared small The active component iron catalyst of crystal grain, so as to significantly improve the selectivity of low-carbon alkene.

The inventive method, step（4）The middle solution impregnating carrier containing active metal component and auxiliary agent, through overdrying after dipping Dry and calcination stepses, the condition of the drying and roasting is conventional, for example, drying steps dry 8-24 at 50-150 DEG C Hour, calcination stepses are calcined 2-10 hours at 350-700 DEG C.

It is a kind of using above method prepare preparation of low carbon olefines by synthetic gas catalyst, using Fe as active component, using K and Mn as Auxiliary agent, Fe weight percentage is 0.5%-20% in catalyst, and auxiliary agent is K and Mn, Fe and auxiliary agent K and Mn matter in catalyst Measuring ratio is respectively（65~75）：（0.5~5）：（23~34）.

The restoring method of above-mentioned preparation of low carbon olefines by synthetic gas catalyst, is reduced using the gaseous mixture of chlorine and hydrogen, Volume content of the chlorine in gaseous mixture is 0.5-10%, preferably 1-5%, and reduction temperature is 300-450 DEG C, recovery time 3-10 Hour, pressure 0.5-2MPa.The selectivity of butylene can be improved using above-mentioned restoring method.

The inventive method uses organic compounds containing nitrogen aqueous solution saturation oxide impregnation alumina supporter first, is done through quick fraction The organic compounds containing nitrogen aqueous solution is concentrated in the internal gutter of carrier after dry, and the organic compounds containing nitrogen aqueous solution is mainly to carrier Inside carries out partially modified.Then using the mixed aqueous solution of nickel salt and gallium salt mainly to the outer surface and outside of alumina support Channel surfaces are mainly modified.The above-mentioned inside and outside duct to alumina support, which carries out uneven modification, makes alumina support Inside and outside duct physico-chemical property is significantly different, inhibits the carbochain of the low-carbon alkene of generation to increase while improving active to greatest extent And saturation is hydrogenated with, improve the conversion ratio of carbon monoxide.The inventive method makes active component iron by way of adsorbent occupy-place Content significantly improves the selectivity of catalyst by gradually increasing from interior outside.The physical and chemical performance of the catalyst, catalytic activity, length The stability of period run is obtained for raising, and the combination property of catalyst protrudes.

Embodiment

The process and effect of the present invention is further illustrated with reference to embodiment, but following examples are not formed to the present invention The limitation of method.

Example 1

Weigh commercial alumina（Pore volume is 0.96ml/g, specific surface area 286.81m²/ g, saturated water adsorptive value 145ml/ G, provided by Fushun branch company of Sinopec catalyst Co., Ltd, following examples and comparative example use the aluminum oxide）, will The pyridine solution saturation that mass concentration is 5% sprays oxide impregnation aluminium, dries 1h after terminating at 95 DEG C immediately, dries pyrrole processed The adsorbance of the pyridine aqueous solution is the 60% of alumina support saturated absorption amount of solution, aging 7h at 60 DEG C, 24 is dried in 100 DEG C Hour, then it is calcined 5 hours obtained modified aluminium oxide supports at 300 DEG C.Above-mentioned modified aluminium oxide supports are sprayed using unsaturated Impregnation nickel, gallium molar concentration are respectively 0.5mol/L, 1mol/L nickel nitrate, gallium nitrate mixed aqueous solution, and dipping is warm To spend for 50 DEG C, dip time 3h, pickup is the 20% of alumina support saturated absorption amount of solution, dries 5h at 120 DEG C, 850 DEG C lower roasting 6h of roasting.The unsaturated spray dipping triethylamine aqueous solution of carrier after roasting, triethylamine aqueous solution spray volume are The 35% of the total saturated water adsorptive value of used carrier, the mass content of triethylamine is the 8% of carrier quality in triethylamine aqueous solution, spray leaching In 100 DEG C of dry 5h after stain.Based on final catalyst Fe content 9wt%, the carrier for adsorbing triethylamine is soaked using equi-volume impregnating Stain iron nitrate aqueous solution, 100 DEG C of dryings 16 hours, is calcined 4 hours in 550 DEG C.It is 3.6wt% by manganese content in catalyst, Fe, K and Mn mass ratio are 70：3：28 meter incipient impregnation manganese nitrates and potassium nitrate mixed liquor, 100 DEG C of dryings 16 hours, It is calcined 4 hours in 550 DEG C, gained catalyst is designated as C-1.C-1 catalyst synthesis gas directly prepares the reaction result of low-carbon alkene As shown in table 1.

Catalyst Evaluation Test is carried out in the continuous fixed bed reactors of high pressure, to be reduced 5 hours at pure 350 DEG C of hydrogen, pressure Power is 1.0MPa.Switching and merging gas is reacted after cooling.Reaction effluent is collected by hot trap, cold-trap respectively.Reaction condition is 280 DEG C, 1200h^-1, 2.0MPa, H₂/CO=1（Mol ratio）.C-1 catalyst synthesis gas directly prepares the 300h reactions of low-carbon alkene As a result it is as shown in table 1.

Example 2

Commercial alumina is weighed, is that 20% diethanol amine aqueous solution saturation sprays oxide impregnation aluminium by mass concentration, after terminating 0.5h is dried at 110 DEG C immediately, the dry adsorbance to the diethanol amine aqueous solution is alumina support saturated absorption amount of solution 40%, aging 4 hours at 80 DEG C, dried 8 hours in 120 DEG C, then be calcined in 400 DEG C 3 hours and obtain modified aluminas Carrier.Above-mentioned modified aluminium oxide supports using unsaturated spray impregnation nickel, gallium molar concentration be respectively 1.5mol/L, 3mol/L nickel nitrate, gallium nitrate mixed aqueous solution, dipping temperature are 60 DEG C, and dip time 2h, pickup is alumina support The 40% of saturated absorption amount of solution, 10h, 900 DEG C of roasting 4h are dried at 90 DEG C.The unsaturated spray dipping of carrier after roasting The coffee aqueous solution, aqueous morphine solution spray volume is the 10% of the total saturated water adsorptive value of used carrier, the quality of morphine in aqueous morphine solution Content is the 2% of carrier quality, oxygen life 5h after spray impregnates, in 90 DEG C of dry 8h.Remaining is designated as with embodiment 1, obtained catalyst C-2,300h evaluation result are shown in Table 1.

Example 3

In addition to the ammonium citrate that mass fraction is 5% is added in the iron nitrate aqueous solution of dipping, remaining is the same as embodiment 1, system Obtain catalyst and be designated as C-3,300h evaluation results are shown in Table 1.

Example 4

In addition to the ammonium citrate that mass fraction is 10% is added in the iron nitrate aqueous solution of dipping, remaining with embodiment 1, Obtained catalysis is designated as C-4, and 300 evaluation results are shown in Table 1.

Example 5

With embodiment 1, difference is to reduce catalyst using the gaseous mixture of chlorine and hydrogen, and chlorine is mixed The volume content closed in gas is 5%, and obtained catalyst is designated as C-5, and 300h evaluation results are shown in Table 1.

Implement 6

With embodiment 1, difference is that catalyst is reduced using the gaseous mixture of chlorine and hydrogen, and chlorine is mixing Volume content in gas is 1%, and, with embodiment 1, obtained catalyst is designated as C-6 for remaining, and 300h evaluation results are shown in Table 1.

Comparative example 1

Except being respectively that 0.5mol/L, 1mol/L nickel nitrate, gallium nitrate mix using saturation spray dipping nickel, gallium molar concentration Outside Heshui solution, with embodiment 1, obtained catalyst is designated as B-1 for remaining, and 300h evaluation results are shown in Table 1.

Comparative example 2

In addition to dipping triethylamine aqueous solution is not sprayed, with embodiment 1, obtained catalyst is designated as B-2,300h evaluation knots for remaining Fruit is shown in Table 1.

The reactivity worth of the catalyst of table 1

Claims

A kind of 1. preparation method of preparation of low carbon olefines by synthetic gas catalyst, it is characterised in that：Comprise the following steps：

（1）The isometric saturation of alumina support impregnates the organic compounds containing nitrogen aqueous solution, is done immediately at 95-110 DEG C after dipping Dry 0.5-1h, dry to the 30- that the adsorbance of the organic compounds containing nitrogen aqueous solution is alumina support saturated absorption amount of solution 60%, modified aluminium oxide supports are then made after aging, drying, roasting；

（2）Prepare the mixed aqueous solution of nickel salt and gallium salt, step（1）The modified aluminium oxide supports of preparation use unsaturated infusion process Impregnate above-mentioned mixed aqueous solution, dry after being calcined 1h-10h at 700 DEG C ~ 1000 DEG C；

（3）Using fountain solution impregnation steps of the unsaturated infusion process containing adsorbent（2）Carrier after roasting, wherein described Adsorbent is the organic amine that carbon number is 2~15, and the addition of described adsorbent accounts for step（2）1% of vehicle weight after roasting ~10%；

（4）Step（3）Carrier impregnation containing adsorbent contains the solution of active metal iron, the impregnating metal again after drying, roasting Auxiliary agent, then preparation of low carbon olefines by synthetic gas catalyst is made after drying, roasting；

Wherein, step（1）Organic compounds containing nitrogen is monoethanolamine, diethanol amine, three ethanol in the organic compounds containing nitrogen aqueous solution One or more in amine and pyridine.
2. according to the method for claim 1, it is characterised in that：Step（1）It is nitrogenous in the organic compounds containing nitrogen aqueous solution to have The weight concentration of machine compound is 1%-35%.
3. according to the method for claim 1, it is characterised in that：Step（1）Aging temperature is 50-95 DEG C, and ageing time is 0.5-10h, drying temperature is 90-150 DEG C after aging, drying time 0.5-36h, is calcined and is calcined 2-15 at 280-500 DEG C Hour.
4. according to the method for claim 1, it is characterised in that：Step（2）Middle nickel salt is nickel chloride, nickel nitrate or nickel sulfate In one or more, gallium salt is gallium nitrate, gallium chloride, the one or more in gallium sulfate.
5. according to the method for claim 1, it is characterised in that：Step（2）The concentration of nickel ion is in mixed aqueous solution 0.1-5mol/L, the molar concentration of gallium ion are two times of nickel ion molar concentration.
6. according to the method for claim 1, it is characterised in that：Step（2）Pickup is that alumina support saturated absorption is molten The 5-60% of liquid measure, dip time 1-5h, dipping temperature are 40-60 DEG C, and drying temperature is 80-150 DEG C after dipping, when drying Between be 2-15h.
7. according to the method for claim 1, it is characterised in that：Step（2）Pickup is that alumina support saturated absorption is molten The 20-50% of liquid measure.
8. according to the method for claim 1, it is characterised in that：Step（3）Middle organic amine is fatty amine, hydramine, acid amides, fat One or more in cyclammonium or aromatic amine.
9. the method according to claim 1 or 8, it is characterised in that：Step（3）Middle organic amine is monoethyl amine, diethylamine, three Ethamine, ethylenediamine, hexamethylene diamine, tert-butylamine, monoethanolamine, diethanol amine, triethanolamine, dimethylformamide, propionamide, butyryl One or more in amine, pyridine, morphine, aniline, diphenylamines, naphthalidine, dinaphthylamine.
10. according to the method for claim 9, it is characterised in that：Step（3）Middle organic amine is diethylamine, triethylamine, morphine In one or more.
11. according to the method for claim 1, it is characterised in that：Step（3）Middle fountain solution of the dipping containing adsorbent, is adopted Sprayed with unsaturation, wherein the volume ratio of unsaturated dipping dip amount used and carrier saturated absorption amount of solution for 0.05 ~ 0.4。
12. according to the method for claim 1, it is characterised in that：Step（3）After middle fountain solution of the dipping containing adsorbent, To be dried under the decomposition temperature no more than selected adsorbent, drying temperature is 60 DEG C~150 DEG C, drying time 0.5h~20h, or Direct impregnation contains the solution of active metal iron after fountain solution of person's dipping containing adsorbent.
13. according to the method for claim 12, it is characterised in that：Drying temperature is 80 DEG C~120 DEG C, drying time 1h ~6h.
14. according to the method for claim 1, it is characterised in that：Step（3）Fountain solution dipping of the middle dipping containing adsorbent After end, next step is directly carried out, or next step is carried out again by health, conditioned time is 0.5~8h.
15. according to the method for claim 1, it is characterised in that：Step（4）Middle auxiliary agent is K and Mn, the synthesis gas system of preparation Fe and auxiliary agent K and Mn mass ratio are respectively in light olefins catalyst（65~75）：（0.5~5）：（23~34）.
16. according to the method for claim 1, it is characterised in that：Step（4）Middle active component Fe and metal promoter K, Mn lead to Infusion process is crossed to support on carrier.
17. according to the method for claim 16, it is characterised in that：Source of iron is one kind in ferric nitrate, iron chloride, ferric sulfate Or it is several, potassium resource is the one or more in potassium nitrate, potassium carbonate, potassium chloride, and manganese source is manganese nitrate or manganese chloride.
18. according to the method for claim 1, it is characterised in that：Step（4）Added in solution containing active metal iron The ammonium citrates of 2-15% in mass.
19. according to the method for claim 18, it is characterised in that：Step（4）Added in solution containing active metal iron The ammonium citrates of 5-10% in mass.
20. according to the method for claim 1, it is characterised in that：Step（4）It is middle with molten containing active metal component and auxiliary agent Liquid impregnated carrier, by drying and calcination stepses, drying steps dry 8-24 hours, calcination stepses at 50-150 DEG C after dipping 2-10 hours are calcined at 350-700 DEG C.
A kind of 21. preparation of low carbon olefines by synthetic gas catalyst prepared using claim 1-20 either method, it is characterised in that：Should Catalyst is using Fe as active component, and using K and Mn as auxiliary agent, Fe weight percentage is 0.5%-20% in catalyst, and Fe is with helping Agent K and Mn mass ratio is respectively（65~75）：（0.5~5）：（23~34）.
22. the restoring method of catalyst described in claim 21, it is characterised in that：Gone back using the gaseous mixture of chlorine and hydrogen Original, volume content of the chlorine in gaseous mixture are 0.5-10%, and reduction temperature is 300-450 DEG C, and the recovery time is 3-10 hours, Pressure is 0.5-2MPa.
23. restoring method according to claim 22, it is characterised in that：Volume content of the chlorine in gaseous mixture is 1- 5%。