CN105709769B

CN105709769B - A kind of synthesis gas alkene catalyst and preparation method thereof

Info

Publication number: CN105709769B
Application number: CN201410723833.0A
Authority: CN
Inventors: 李�杰; 张信伟; 张舒东; 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: 2014-12-04
Filing date: 2014-12-04
Publication date: 2017-07-14
Anticipated expiration: 2034-12-04
Also published as: CN105709769A

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 acid solution of the isometric saturation dipping sugar of alumina support, it is the 30 60% of alumina support saturated absorption amount of solution to dry to the adsorbance of the acid solution of sugar, and modified aluminium oxide supports are then made after aging, drying, roasting；（2）Step（1）The modified aluminium oxide supports of preparation are using unsaturated impregnation zinc solution, dry roasting；（3）Using fountain solution impregnation steps of the unsaturated infusion process containing adsorbent（2）Carrier after roasting；（4）Step（3）Carrier containing adsorbent impregnates the solution containing active metal iron and auxiliary agent manganese after drying, and preparation of low carbon olefines by synthetic gas catalyst is made after drying, roasting.The catalyst has the characteristics of long-term operation activity stability is high, is conducive to commercial Application and popularization.

Description

A kind of synthesis gas alkene catalyst and preparation method thereof

Technical field

The present invention relates to a kind of synthesis gas alkene catalyst and preparation method thereof, a kind of high activity is related in particular to steady 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 be shifted.Compared with petroleum resources, coal and natural Gas resource relative abundance, develops the low-carbon alkene production technology based on coal and natural gas and has great importance.From synthesis gas （It can be converted to by natural gas and coal）Direct preparing ethylene, the exploitation of 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 employs noble metal or rare metal, and more than ten plant chemistry such as niobium, gallium, praseodymium, scandium, indium, cerium, lanthanum, ytterbium Element, ethylene selectivity is 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 high cost.CN01144691.9 discloses the nano-catalytic of a kind of preparation of ethylene by use of synthetic gas, propylene Agent and preparation method thereof, uses the combination technique of laser pyrolysis processes combination solid phase reaction to be prepared for Fe₃Fe bases nanometer based on C Catalyst is applied and preparing low-carbon olefin, and achieves certain effect, but is due to need practical laser technology, is made 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 Open a kind of for preparation of ethylene by use of synthetic gas, propylene, iron/activated-carbon catalyst of butene reaction, carrier, Fe are used as using activated carbon 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 used as catalyst carrier not only bad mechanical strength but also shaping of catalyst Difficulty, influences the service life and stability of catalyst, is unfavorable for commercial Application.

CN102441383A, CN101940958A, CN102441400A, CN102441384A are respectively adopted nitrogenous organic The mode such as compound solution, acid solution, the cushioning liquid of ammonium salt-containing, the hydro-thermal process of sugar is carried out at dipping to silica-gel carrier Reason, prepares Fe base silica gel supported synthesis gas and directly prepares light olefins catalyst, reduce Fe and SiO₂Between carrier Strong interaction.But above-mentioned Fe bases silica gel supported synthesis gas directly prepares the work of the long-term operation of light olefins catalyst Property stability still need further raising.

The content of the invention

In view of the shortcomings of the prior art, a kind of iron-based support type synthesis gas system using aluminum oxide as carrier of present invention offer is low Carbene hydrocarbon catalyst and preparation method thereof, the catalyst has the characteristics of long-term operation activity stability is high, is conducive 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）Dried immediately at 95-110 DEG C after the acid solution of the isometric saturation dipping sugar of alumina support, dipping 0.5-1h, is dried to the 30-60% that the adsorbance of the acid solution of sugar is alumina support saturated absorption amount of solution, then through old Modified aluminium oxide supports are made after change, dry, roasting；

（2）Step（1）The modified aluminium oxide supports of preparation using unsaturated impregnation zinc solution, dry after 1h-10h is calcined at 700 DEG C ~ 1000 DEG C, preferably 2h-8h is calcined at 800 DEG C ~ 900 DEG C；

（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 and metal promoter manganese, through drying, Or else saturation spray impregnating metal auxiliary agent potassium solution, then the obtained preparation of low carbon olefines by synthetic gas catalysis after drying, roasting after roasting Agent.

The inventive method step（1）The sugar that sugared acid solution used is used includes various water-soluble sugar, such as each Monose or disaccharide are planted, the aqueous solution such as fructose, glucose, sucrose, maltose, preferably sucrose acid solution is specifically included.The acid of sugar Property solution in sugared mass concentration be 1%-35%, preferably 5%-20%.Acid solution pH containing sugar is 0.1-6.5, and preferable ph is 1-3, can use the pH value of arbitrary inorganic acid or organic acid-conditioning solution, preferably hydrochloric acid, sulfuric acid, nitric acid, phosphoric acid, first Acid, acetic acid etc..Aging temperature is 50-95 DEG C, and preferably 60 ~ 80 DEG C, ageing time is 0.5-10h, preferably 2-5h.Done after aging Dry temperature is 90-150 DEG C, and drying time is 0.5-36h, and 8-24h is dried preferably at 100-120 DEG C.Roasting is at 280-500 DEG C Lower roasting 2-15 hours, is calcined 3-5 hours preferably at 300-450 DEG C.

The inventive method, step（2）Middle zinc salt includes the one or more in zinc chloride, zinc nitrate or zinc sulfate.Zinc salt Solution is that the mass fraction of zinc salt in the aqueous solution of zinc salt, zinc solution is 5-10%.

The inventive method, step（2）The pickup of middle zinc solution is the 5- of alumina support saturated absorption amount of solution 60%, preferably 20-50%.Dip time is 1-5h, and dipping temperature is 40-60 DEG C.Drying temperature is 80-150 DEG C after dipping, is dried Time is 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 Or it is 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, using unsaturation dipping, preferably with unsaturation Spray, wherein the volume ratio of unsaturated dipping dip amount used and carrier saturated absorption amount of solution is 0.05 ~ 0.4.Dipping contains Have after 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 shower nozzle that atomizing effect should be selected good makes solution uniformly divide It is scattered on alumina support.After fountain solution dipping of the dipping containing adsorbent terminates, next step can be directly carried out, be may also pass through Health carries out next step again, and conditioned time is 0.5~8h.

The inventive method, step（4）The amount of middle unsaturated spray impregnating metal auxiliary agent potassium solution is molten for carrier saturated absorption The 50-90% of liquid measure.Fe and auxiliary agent K and Mn mass ratio are respectively in the preparation of low carbon olefines by synthetic gas catalyst of preparation（65~ 75）：（0.5~5）：（23~34）.Active metal solution or compounding agent solution preparation method are that known to technical staff, its solution is dense Degree can be adjusted by the consumption of each compound, so as to prepare the catalyst of specified activity component and auxiliary agent content.Required activity The raw material of component and auxiliary agent is generally the compound of the types such as salt, oxide or acid, and such as source of iron is generally from ferric nitrate, chlorination One or more in iron, ferric sulfate, one or more of the potassium resource in potassium nitrate, potassium carbonate, potassium chloride, manganese source is typically come From manganese nitrate or manganese chloride.

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

The inventive method, step（4）It is middle with the 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.

Preparation of low carbon olefines by synthetic gas catalyst prepared by a kind of use above method, using Fe as active component, using K and Mn as Fe weight percentage is 0.5%-20% in auxiliary agent, 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%, and preferably 1-5%, reduction temperature is 300-450 DEG C, and the recovery time is 3-10 Hour, pressure is 0.5-2MPa.The selectivity of butylene can be improved using above-mentioned restoring method.

The inventive method is sugared after being dried through quick fraction first using the acid solution saturation oxide impregnation alumina supporter of sugar Acid solution is concentrated in the internal gutter of carrier, and sugared acid solution mainly carries out partially modified to carrier inside.Then adopt Mainly it is modified with the outer surface main to alumina support of unsaturated dipping zinc solution and outside channel surfaces.It is above-mentioned right The inside and outside duct of alumina support, which carries out uneven modification, makes the inside and outside duct physico-chemical property of alumina support significantly different, most Limits inhibit the carbochain of the low-carbon alkene of generation to increase and hydrogenation saturation while improving activity, improve carbon monoxide Conversion ratio.The inventive method makes active component iron content and auxiliary agent manganese gradually be increased from interior by outer by way of adsorbent occupy-place Plus, auxiliary agent potassium is distributed into eggshell type, significantly improves the selectivity of catalyst.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 is protruded.

Embodiment

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

Example 1

Weigh commercial alumina（Pore volume is 0.96ml/g, and specific surface area is 286.81m²/ g, saturated water adsorptive value is 145ml/ G, is provided by Fushun branch company of Sinopec catalyst Co., Ltd, and following examples and comparative example use the aluminum oxide）, will Sucrose mass concentration is equal to 3 for 5% aqueous solution sulphur acid for adjusting pH value, and saturation is sprayed after oxide impregnation aluminium terminates immediately 95 1h is dried at DEG C, the adsorbance for drying the acid solution of sugaring is the 60% of alumina support saturated absorption amount of solution, at 60 DEG C Aging 7h, dries 24 hours in 100 DEG C, is then calcined 5 hours obtained modified aluminium oxide supports at 300 DEG C.Above-mentioned modified oxygen Changing alumina supporter uses unsaturated spray impregnation mass fraction for 5% zinc nitrate aqueous solution, and dipping temperature is 50 DEG C, leaching Stain time 3h, pickup is dry 5h at the 20% of alumina support saturated absorption amount of solution, 120 DEG C, and 850 DEG C of roastings are lower to be calcined 6h.Carrier unsaturation spray dipping triethylamine aqueous solution after roasting, triethylamine aqueous solution spray volume is always satisfied for used carrier With the 35% of water absorption, the mass content of triethylamine is the 8% of carrier quality in triethylamine aqueous solution, at 100 DEG C after spray dipping Dry 5h.Based on final catalyst Fe content 9wt%, the carrier of absorption triethylamine impregnates nitric acid molten iron using equi-volume impregnating Solution, 100 DEG C of dryings 16 hours are calcined 4 hours in 550 DEG C.It is 70 by the mass ratio of Fe, K and Mn in catalyst：3：28 Meter, unsaturation spray dipping potassium nitrate solution, pickup is the 60% of carrier saturated absorption amount of solution, 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 knot of low-carbon alkene Fruit is 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, sucrose mass concentration is equal to 1, saturation spray for 20% aqueous solution sulphur acid for adjusting pH value Drench after oxide impregnation aluminium terminates and dry 0.5h at 110 DEG C immediately, it is carrying alumina to dry to the adsorbance of the acid solution of sugar The 40% of body saturated absorption amount of solution, aging 4 hours at 80 DEG C, dries 8 hours in 120 DEG C, is then calcined 3 in 400 DEG C Hour obtains modified aluminium oxide supports.Above-mentioned modified aluminium oxide supports use unsaturated impregnation mass fraction for 10% sulphur The sour zinc aqueous solution, dipping temperature is 60 DEG C, dip time 2h, and pickup is the 40% of alumina support saturated absorption amount of solution, 10h, 900 DEG C of roasting 4h are dried at 90 DEG C.Carrier unsaturation spray dipping aqueous morphine solution after roasting, aqueous morphine solution spray It is the 2% of carrier quality, spray to drench the mass content that volume is morphine in the 10% of the total saturated water adsorptive value of used carrier, aqueous morphine solution Health 5h after dipping is drenched, in 90 DEG C of dry 8h.By final catalyst Fe content 9wt%, manganese content for 3.6wt% based on, adsorb morphine Carrier ferric nitrate and manganese nitrate aqueous solution are impregnated using equi-volume impregnating, 100 DEG C of dryings 16 hours are calcined 4 in 550 DEG C Hour.It is 70 by the mass ratio of Fe, K and Mn in catalyst：3：28 meters, unsaturation spray impregnates potassium nitrate solution, and pickup is The 80% of carrier saturated absorption amount of solution, 100 DEG C of dryings 16 hours are calcined 4 hours, gained catalyst is designated as C-2 in 550 DEG C, 300h evaluation results 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 be the same as Example 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 be the same as Example 1, Obtained catalysis is designated as C-4, and 300 evaluation results are shown in Table 1.

Example 5

Be the same as Example 1, difference is that catalyst is reduced 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

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

Comparative example 1

In addition to using saturation and spraying impregnating effect fraction for 5% zinc nitrate aqueous solution, catalysis is made in remaining be the same as Example 1 Agent is designated as B-1, and 300h evaluation results are shown in Table 1.

Comparative example 2

In addition to dipping triethylamine aqueous solution is not sprayed, remaining be the same as Example 1, obtained catalyst is designated as B-2, and 300h evaluates knot Fruit is shown in Table 1.

The reactivity worth of the catalyst of table 1

Claims

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

（1）0.5-1h is dried at 95-110 DEG C immediately after the acid solution of the isometric saturation dipping sugar of alumina support, dipping, Dry to sugar acid solution adsorbance be alumina support saturated absorption amount of solution 30-60%, then through aging, drying, Modified aluminium oxide supports are made after roasting；

（2）Step（1）The modified aluminium oxide supports of preparation using unsaturated impregnation zinc solution, dry after 700 DEG C ~ 1h-10h is calcined at 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 and auxiliary agent manganese, after drying, roasting again Unsaturation spray impregnating metal auxiliary agent potassium solution, then preparation of low carbon olefines by synthetic gas catalyst is made after drying, roasting；

Wherein, step（1）The sugar that sugared acid solution used is used be fructose, glucose, sucrose, maltose in one kind or Several, aging temperature is 50-95 DEG C, and ageing time is that drying temperature is 90-150 DEG C after 0.5-10h, aging, and drying time is 0.5-36h, roasting is calcined 2-15 hours at 280-500 DEG C.

2. according to the method described in claim 1, it is characterised in that：Step（1）Sugared mass concentration is in the acid solution of sugar 1%-35%, the acid solution pH containing sugar are 0.1-6.5.

3. according to the method described in claim 1, it is characterised in that：Step（2）After drying 2h- is calcined at 800 DEG C ~ 900 DEG C 8h。

4. according to the method described in claim 1, it is characterised in that：Step（2）Middle zinc salt is selected from zinc chloride, zinc nitrate or sulfuric acid One or more in zinc.

5. according to the method described in claim 1, it is characterised in that：Step（2）Middle zinc solution is the aqueous solution of zinc salt, zinc salt The mass fraction of zinc salt is 5-10% in solution.

6. according to the method described in claim 1, it is characterised in that：Step（2）The pickup of middle zinc solution is carrying alumina The 5-60% of body saturated absorption amount of solution, dip time is 1-5h, and dipping temperature is that drying temperature is 80- after 40-60 DEG C, dipping 150 DEG C, drying time is 2-15h.

7. according to the method described in claim 1, it is characterised in that：Step（2）The pickup of middle zinc solution is carrying alumina The 20-50% of body saturated absorption amount of solution.

8. according to the method described in claim 1, it is characterised in that：Step（3）Middle organic amine be selected from fatty amine, hydramine, acid amides, One or more in aliphatic cyclic amine or aromatic amine.

9. method according to claim 8, it is characterised in that：Step（3）Middle organic amine is selected from 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. method according to 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 described in 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 described in claim 1, it is characterised in that：Step（3）After middle fountain solution of the dipping containing adsorbent, Dried under the decomposition temperature no more than selected adsorbent, or direct impregnation contains the solution of active metal iron, drying temperature For 60 DEG C~150 DEG C, drying time 0.5h~20h.

13. method according to claim 12, it is characterised in that：Drying temperature is 80 DEG C~120 DEG C, and drying time is 1h ~6h.

14. according to the method described in claim 1, it is characterised in that：Step（4）The preparation of low carbon olefines by synthetic gas catalysis of middle preparation Fe and auxiliary agent K and Mn mass ratio are respectively in agent（65~75）：（0.5~5）：（23~34）.

15. according to the method described in claim 1, it is characterised in that：Step（4）Middle unsaturated spray impregnating metal auxiliary agent potassium is molten The amount of liquid is the 50-90% of carrier saturated absorption amount of solution.

16. according to the method described in claim 1, 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.

17. according to the method described in claim 1, it is characterised in that：Step（4）Solution containing active metal iron and auxiliary agent manganese In add the ammonium citrates of 2-15% in mass.

18. method according to claim 17, it is characterised in that：Step（4）It is molten containing active metal iron and auxiliary agent manganese The ammonium citrates of 5-10% in mass are added in liquid.

19. according to the method described in claim 1, it is characterised in that：Step（4）By dry and calcination stepses after dipping, do Dry step is dried 8-24 hours at 50-150 DEG C, and calcination stepses are calcined 2-10 hours at 350-700 DEG C.

20. preparation of low carbon olefines by synthetic gas catalyst prepared by a kind of use claim 1-19 either method, it is characterised in that：Institute Catalyst is stated using Fe as active component, using K and Mn as auxiliary agent, in catalyst Fe weight percentage be 0.5%-20%, Fe with Auxiliary agent K and Mn mass ratio is respectively（65~75）：（0.5~5）：（23~34）.

21. the restoring method of catalyst described in claim 20, it is characterised in that：Gone back using the gaseous mixture of chlorine and hydrogen Original, volume content of the chlorine in gaseous mixture is 0.5-10%, and reduction temperature is 300-450 DEG C, and the recovery time is 3-10 hours, Pressure is 0.5-2MPa.

22. restoring method according to claim 21, it is characterised in that：Volume content of the chlorine in gaseous mixture is 1- 5%。