(3) summary of the invention
But the technical problem to be solved in the present invention is to provide a kind of preparation of simple industrial application has wide aperture, bigger serface γ-Al
2O
3Novel method.
For solving the problems of the technologies described above, the present invention adopts following technical scheme:
A kind of γ-Al
2O
3The preparation method of nanofiber comprises the following steps:
(a) inorganic salt containing aluminium solution and alkaline sedimentation agent solution are mixed according to volume ratio 1: 2~5, in described inorganic salt containing aluminium solution, the mass percent of inorganic salt containing aluminium is 5~40%, in described alkaline sedimentation agent solution, the mass percent of water is 80-95%, reacts after mixing to obtain suspension liquid under 30~100 ℃ of conditions;
(b) the suspension liquid filtration is obtained filter cake, and then remove impurity by making beating, filtration step in deionized water, obtain filter cake I;
(c) will be processed in organic solvent again by the filter cake I that step (b) makes, and then filter, reclaim organic solvent and obtain filter cake II;
(d) will carry out calcination process at 300~600 ℃ by the filter cake II that step (c) makes, obtain γ-Al
2O
3Nano-fiber material.
In step of the present invention (a), we find, the temperature of precipitin reaction and the concentration of raw material have important impact to particle diameter and the structure of controlling precursor particle in this step reaction.By controlling these key factors in step (a), can obtain: (1) has the particle of appropriate particle size, thereby is conducive to filter and washing; (2) between particle, water content is lower, reduces roasting process and caves in because the surface tension phenomenon causes the hole.Therefore, the preferred aluminum nitrate of described inorganic salt containing aluminium and Tai-Ace S 150; In described inorganic salt containing aluminium solution, the mass percent of inorganic salt containing aluminium is 5~40%, is preferably 10~30%, more preferably 10~20%.The preferred aqueous sodium carbonate of described alkaline sedimentation agent solution, aqueous sodium hydroxide solution or ammonia soln, more preferably aqueous sodium carbonate.In preferred steps (a), the temperature of precipitin reaction is 60~100 ℃.
In step of the present invention (b), suspension liquid is filtered obtains filter cake, and then in deionized water by repeatedly pull an oar, the washing step such as filtration to be to remove impurity, can make through the specific surface area of roasting rear oxidation aluminium larger.
In step of the present invention (c), with an organic solvent to carrying out replacement Treatment by the water in step (a) and the precipitated filter cakes that (b) obtains, cause the hole to cave in further reduction roasting process due to the surface tension phenomenon and the phenomenon such as particle aggregation.Described organic solvent can be selected from following a kind of or several combination arbitrarily: methyl alcohol, ethanol, propyl alcohol, butanols.
In step of the present invention (d), preferably with filter cake II at 300-600 ℃ of lower roasting 2-6 hour.Preferred roasting condition was: 400 ℃ of roastings 5 hours.
Described γ-the Al of the concrete recommendation of the present invention
2O
3The preparation method of nanofiber carries out in accordance with the following steps:
(a) inorganic salt containing aluminium solution and alkaline sedimentation agent solution are mixed according to volume ratio 1: 2~5, react under 30~100 ℃ of conditions and obtain suspension liquid; Described inorganic salt containing aluminium solution is aluminum nitrate aqueous solution or aluminum sulfate aqueous solution, and in described inorganic salt containing aluminium solution, the mass percent of inorganic salt is 5~40%; Described alkaline sedimentation agent solution is aqueous sodium carbonate, aqueous sodium hydroxide solution or ammonia soln, and in described alkaline sedimentation agent solution, the mass percent of water is 80-95%;
(b) the suspension liquid filtration is obtained filter cake, and then remove impurity by making beating, filtration step in deionized water, obtain filter cake I;
(c) will be processed in organic solvent again by the filter cake I that step (b) makes, and then filter, reclaim organic solvent and obtain filter cake II; Described organic solvent is selected from following a kind of or several combination arbitrarily: methyl alcohol, ethanol, propyl alcohol, butanols;
The filter cake II that (d) will be made by step (c) obtained γ-Al at 300~600 ℃ of roasting 2-6 hours
2O
3Nano-fiber material.
The Al that the present invention makes
2O
3Material, particle are fibrous particle, and its crystal formation is the γ crystal formation; The material specific surface area is not less than 300m
2g
-1, pore volume is not less than 1.5cm
3g
-1, the aperture is not less than 10nm.
Compared with the prior art, the present invention has the following advantages:
(1) novel method of the present invention report pattern that is conducive to control aluminium oxide particles to form fibrous particle, forms larger aperture, the Al that makes by piling up between these particles
2O
3Material has bigger serface, wide-aperture characteristics.
(2) preparation process of the present invention's report does not need complicated equipment and exacting terms to control, and the raw material that uses is cheap, and the preparation process environmental friendliness is convenient to suitability for industrialized production.
(5) embodiment
The below is described further technical scheme of the present invention with specific embodiment, but protection scope of the present invention is not subjected to the restriction of the following example.
Embodiment (1)
With 88 gram Al (NO
3)
39H
2O and 50 gram Na
2CO
3Be dissolved in respectively and be made into 15wt% and 6wt% solution in 250 and 750 ml deionized water, then with Al (NO
3)
3And Na
2CO
3Solution mixes under 95 ℃ of conditions and carries out precipitin reaction.Resulting suspension liquid is filtered obtain filter cake, with deionized water, filter cake is washed, and then filter.Through repeatedly the washing and filtration treatment after, with ethanol, filter cake is processed.After filtration, reclaim ethanol after, resulting filter cake is obtained Al through 400 ℃ of roastings after 5 hours
2O
3Sample.Fig. 1 is TEM figure, shows to exist nanometer fibrous particle.Fig. 2 is XRD figure, shows that this material is γ-Al
2O
3
Embodiment (2)
With 78 gram Al
2(SO
4)
318H
2O and 50 gram Na
2CO
3Be dissolved in respectively and be made into 12wt% and 6wt% solution in 250 and 750 ml deionized water, then with Al
2(SO
4)
3And Na
2CO
3Solution mixes under 95 ℃ of conditions and carries out precipitin reaction.Resulting suspension liquid is filtered obtain filter cake, with deionized water, filter cake is washed, and then filter.After repeatedly washing and filtering, with ethanol, precipitated filter cakes is processed.After filtration, reclaim ethanol after, resulting filter cake is obtained Al through 400 ℃ of roastings after 5 hours
2O
3Sample.
Embodiment (3)
With 17.7 gram Al (NO
3)
39H
2O and 10 gram Na
2CO
3Be dissolved in respectively and be made into 15wt% and 6wt% solution in 50 and 150 ml deionized water, then with Al (NO
3)
3And Na
2CO
3Solution mixes at ambient temperature and carries out precipitin reaction.Resulting suspension liquid is filtered obtain filter cake, with deionized water, filter cake is washed, and then filter.After repeatedly washing and filtering, with ethanol, precipitated filter cakes is processed.After filtration, reclaim ethanol after, resulting filter cake is obtained Al through 400 ℃ of roastings after 5 hours
2O
3Sample.
Embodiment (4)-----F-T building-up reactions
Prepare CoRu/Al take the aluminum oxide of embodiment 1 preparation and commercial aluminum oxide (seeing Table 1) as carrier respectively
2O
3Catalyzer.
Catalyst preparation step: with 4.2 gram Co (NO
3)
26H
2O and 0.14 gram Ru (NO) (NO
3)
3And polyoxyethylene glycol (molecular weight 400 2vol%) joins 120cm under the condition of vigorous stirring
3In methyl alcohol and water mixed solution (the mixed volume ratio is 3: 1).After reaction 2h under 90 ℃, with 3 gram Al
2O
3Carrier joins in formed colloidal sol, and continues vigorous stirring.After evaporating solvent under 100 ℃ of conditions, can make the presoma of cobalt metal and ruthenium load to Al
2O
3On carrier, and obtain the colloidal solid material.The roasting under 400 ℃ of conditions of this colloidal solid material was obtained CoRuO in 4 hours
x/ Al
2O
3Catalyzer.At last, pass through H
2Reduction can prepare CoRu/Al
2O
3Catalyzer (Co=22wt.%, (Ru/Co)
at.=0.03).
By fixed-bed reactor, the synthetic performance of the F-T of catalyzer has been carried out evaluation test.Reaction conditions is 210 ℃, 2000KPa, H
2/ CO=2.With N
2As interior mark, by gas-chromatography to CO, N
2, CH
4, CO
2Carry out online qualitative and quantitative analysis Deng gas-phase product.Test-results shows, under the chemical constitution prerequisite identical with reaction conditions, the aluminum oxide by embodiment 1 preparation is that the catalyzer of carrier preparation has higher CO conversion rate (h than the catalyzer of the preparation take commercial aluminum oxide as carrier
-1).
Table 1: the texture data of alumina material
Table 2:CoRu/Al
2O
3The F-T building-up reactions performance of catalyzer
CO conversion rate (the per hour CO mole number of every mole metal cobalt conversion)