CA1068667A - Porous aluminous bodies produced by agglomeration of powders - Google Patents
Porous aluminous bodies produced by agglomeration of powdersInfo
- Publication number
- CA1068667A CA1068667A CA217,778A CA217778A CA1068667A CA 1068667 A CA1068667 A CA 1068667A CA 217778 A CA217778 A CA 217778A CA 1068667 A CA1068667 A CA 1068667A
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- Prior art keywords
- bayerite
- alumina
- weight
- porous
- zeolites
- Prior art date
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
- B01J37/00—Processes, in general, for preparing catalysts; Processes, in general, for activation of catalysts
- B01J37/0009—Use of binding agents; Moulding; Pressing; Powdering; Granulating; Addition of materials ameliorating the mechanical properties of the product catalyst
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
- B01J20/00—Solid sorbent compositions or filter aid compositions; Sorbents for chromatography; Processes for preparing, regenerating or reactivating thereof
- B01J20/02—Solid sorbent compositions or filter aid compositions; Sorbents for chromatography; Processes for preparing, regenerating or reactivating thereof comprising inorganic material
- B01J20/06—Solid sorbent compositions or filter aid compositions; Sorbents for chromatography; Processes for preparing, regenerating or reactivating thereof comprising inorganic material comprising oxides or hydroxides of metals not provided for in group B01J20/04
- B01J20/08—Solid sorbent compositions or filter aid compositions; Sorbents for chromatography; Processes for preparing, regenerating or reactivating thereof comprising inorganic material comprising oxides or hydroxides of metals not provided for in group B01J20/04 comprising aluminium oxide or hydroxide; comprising bauxite
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
- B01J21/00—Catalysts comprising the elements, oxides, or hydroxides of magnesium, boron, aluminium, carbon, silicon, titanium, zirconium, or hafnium
- B01J21/02—Boron or aluminium; Oxides or hydroxides thereof
- B01J21/04—Alumina
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- C—CHEMISTRY; METALLURGY
- C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
- C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
- C04B14/00—Use of inorganic materials as fillers, e.g. pigments, for mortars, concrete or artificial stone; Treatment of inorganic materials specially adapted to enhance their filling properties in mortars, concrete or artificial stone
- C04B14/02—Granular materials, e.g. microballoons
- C04B14/30—Oxides other than silica
- C04B14/303—Alumina
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- Chemical Kinetics & Catalysis (AREA)
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- Civil Engineering (AREA)
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- Analytical Chemistry (AREA)
- Catalysts (AREA)
- Solid-Sorbent Or Filter-Aiding Compositions (AREA)
- Compounds Of Alkaline-Earth Elements, Aluminum Or Rare-Earth Metals (AREA)
- Filtering Materials (AREA)
Abstract
ABSTRACT OF THE DISCLOSURE
It is known to prepare porous aluminous bodies to act as catalysis or carriers for catalysis in various industrial processes. Unfortunately, such aluminous bodies do not have sufficient mechanical strength and tend to physically break-down when in use at temperatures in the order of about 1,000°C.
Thus, the utility of the known porous aluminous bodies is restricted. The present invention seeks to overcome this draw-back by providing porous aluminous bodies having a resistance to crushing of from about 2 kg to about 18 kg; produced by humidification and agglomeration of compositions in powder form comprising at least 15% by weight bayerite prepared by the action of hot gases on a hydrated alumina comprising bayerite said bayerite containing no more than 10% by weight residual water which can be removed by high temperature calcination, from 0 to about 70% by weight of an element selected from the group comprising cellulose, zeolites, molecular sieves, oxides and metals and the balance alumina, the agglomeration operation being followed by activation by calcination at a temperature of from about 600°C to about 1,000°C for a period of time from about 2 to 24 hours.
It is known to prepare porous aluminous bodies to act as catalysis or carriers for catalysis in various industrial processes. Unfortunately, such aluminous bodies do not have sufficient mechanical strength and tend to physically break-down when in use at temperatures in the order of about 1,000°C.
Thus, the utility of the known porous aluminous bodies is restricted. The present invention seeks to overcome this draw-back by providing porous aluminous bodies having a resistance to crushing of from about 2 kg to about 18 kg; produced by humidification and agglomeration of compositions in powder form comprising at least 15% by weight bayerite prepared by the action of hot gases on a hydrated alumina comprising bayerite said bayerite containing no more than 10% by weight residual water which can be removed by high temperature calcination, from 0 to about 70% by weight of an element selected from the group comprising cellulose, zeolites, molecular sieves, oxides and metals and the balance alumina, the agglomeration operation being followed by activation by calcination at a temperature of from about 600°C to about 1,000°C for a period of time from about 2 to 24 hours.
Description
1q:1 6866~ .
. . .
; The invention concerns porous aluminous bodies produced ~rom starting materials in powder form, comprising bayerite.
It ~ known that porous alumina bodies are widely used in adsorption and for catalysis. Depending on each particular use, particularly in catalysis, well defined ., ~
characteristics as regards specific surface area and porosity ~ -~
are requirecl, anQ, in tne vas~ majority of cases, a high level ~ ;
of mechanical resistance to crushing and very often to - attrition i~l desirable.
For some of these uses, the requirement is for porous aluminous bodies which have, besides microporosity corresponding to a certain specific surface area required for the respective activity, also substantial macroporosity, facilitate gaseous exchanges. It is apparent that in that case, the value of the total porosity generally resul~s in an excessive drop in the mechanical strength characteristics : :. ...
of the aluminous bodies us~ed, whlch should be avoi~e~ when the uses in question concern, for example, the catalytic purifi- -cation of toxic gases emitted by engines; the vi~ration o~
such engines increases the speedat which the porous bodies acting as catalytic supports wear out.
... .. . .
In addition, in many cases, the characteristics in ;
respéct of mechanical strength of su~h porous aluminous bodies must be maintained at sufficient values for periods of greater or lesser length, and at fairly elevated temperatures which ~;
~ .
~ - can be of the order of 1000C.
:, :
Frequently~ the porous aluminous bodies used are `~i produced by agglomeration of powders, and many processes have 3 been proposed for imparting su~stantial degrees of ,, - ..
. . .
; The invention concerns porous aluminous bodies produced ~rom starting materials in powder form, comprising bayerite.
It ~ known that porous alumina bodies are widely used in adsorption and for catalysis. Depending on each particular use, particularly in catalysis, well defined ., ~
characteristics as regards specific surface area and porosity ~ -~
are requirecl, anQ, in tne vas~ majority of cases, a high level ~ ;
of mechanical resistance to crushing and very often to - attrition i~l desirable.
For some of these uses, the requirement is for porous aluminous bodies which have, besides microporosity corresponding to a certain specific surface area required for the respective activity, also substantial macroporosity, facilitate gaseous exchanges. It is apparent that in that case, the value of the total porosity generally resul~s in an excessive drop in the mechanical strength characteristics : :. ...
of the aluminous bodies us~ed, whlch should be avoi~e~ when the uses in question concern, for example, the catalytic purifi- -cation of toxic gases emitted by engines; the vi~ration o~
such engines increases the speedat which the porous bodies acting as catalytic supports wear out.
... .. . .
In addition, in many cases, the characteristics in ;
respéct of mechanical strength of su~h porous aluminous bodies must be maintained at sufficient values for periods of greater or lesser length, and at fairly elevated temperatures which ~;
~ .
~ - can be of the order of 1000C.
:, :
Frequently~ the porous aluminous bodies used are `~i produced by agglomeration of powders, and many processes have 3 been proposed for imparting su~stantial degrees of ,, - ..
-2- ~ `
:~ ;. .
macroporosity to such bodies. Besides the general processes which can be applied to most agglomerata~le materlals and which comprise, for example, introducing into the powder, compositions to be agglomerated, materials o~ varying nature ;~~ 5 which can disappear (e.g. by volatilization) after the agglomerated bodies have been ~ormed, leaving therein e~her their own volume in the form of pores or even a volume which is larger than their own volume, by vlrtue o~ the emisslon ~ ;
of a gas. There are a certain number of processes which are more closely related to the particular propertles o~ alumina, ` which, as is well known, exists in various amorphous or cry-. . .
stalline~ hydrated or unhydrated forms, the textures o~ whlch can ~lffer widely.
.. . . .
'~ Of the processes which result in the production of porous bodies formed by the agglomeratlon of alumina, that descrl~ed in French patent ~o. 1,Q77,163 in the name of PECHINEY gives particularly attractive results. This -process comprises partially and rapidly dehydrating in a ~ ; stream of hot gases, hydrated aluminasin the form of parti- -r` 20 cles, whlch are then in a highly alsorganized state and which, after an optional crushing operation and after humidification, -~ are capable o~ being agglomerated in varlous forms and hardening by a setting phenomenon similar to that of hydraulic -. .. .
binding agents. This process is at present very wl~ely applied to alumina trihydrate, called hydrargillite or gibbsite, and ` which is produced, as is well known, ~y tne Bayer process, for the purposes of providing the aluminum industry with the ~-alumina which it requires. After produclng such ~o~les ~y ,;
agglomeratlon, it is necessary to carry out an activation
:~ ;. .
macroporosity to such bodies. Besides the general processes which can be applied to most agglomerata~le materlals and which comprise, for example, introducing into the powder, compositions to be agglomerated, materials o~ varying nature ;~~ 5 which can disappear (e.g. by volatilization) after the agglomerated bodies have been ~ormed, leaving therein e~her their own volume in the form of pores or even a volume which is larger than their own volume, by vlrtue o~ the emisslon ~ ;
of a gas. There are a certain number of processes which are more closely related to the particular propertles o~ alumina, ` which, as is well known, exists in various amorphous or cry-. . .
stalline~ hydrated or unhydrated forms, the textures o~ whlch can ~lffer widely.
.. . . .
'~ Of the processes which result in the production of porous bodies formed by the agglomeratlon of alumina, that descrl~ed in French patent ~o. 1,Q77,163 in the name of PECHINEY gives particularly attractive results. This -process comprises partially and rapidly dehydrating in a ~ ; stream of hot gases, hydrated aluminasin the form of parti- -r` 20 cles, whlch are then in a highly alsorganized state and which, after an optional crushing operation and after humidification, -~ are capable o~ being agglomerated in varlous forms and hardening by a setting phenomenon similar to that of hydraulic -. .. .
binding agents. This process is at present very wl~ely applied to alumina trihydrate, called hydrargillite or gibbsite, and ` which is produced, as is well known, ~y tne Bayer process, for the purposes of providing the aluminum industry with the ~-alumina which it requires. After produclng such ~o~les ~y ,;
agglomeratlon, it is necessary to carry out an activation
3 operation thereon, by calcination, in order to provlae them `
.,. ~
'~` ~'~
~ -3- -., ,~ .
... -- .. . . . . . .
. ,. . ~ . . ~. .
: : - : , .
~68667 with the desired specific surface area.
However, it is difficult to impart porosity comprising . ~ .
pores of large size, to bodies which are produced by the -~
agglomeration o particles of partially dehydrated hydrargillite. -~
Some processes make it possible to achieve this aim, in -~
! ( ' ' . ' particular regulating the amount of humidification water and ~ -.
using a very restricted range of grain sizes in respect of the particles. These processes are not without disadvantage; for example, the industrial production of a restricted range of grain sizes is always a fairly difficult problem to overcome, as is well known.
It is however possible to produce porous alumina bodies which ha~e macroporosity, by using hydrated aluminas : ,:
:1 which are different from hydrargillite, as the starting materials which are to be partially dehydrated in streams of --., ' . ' ':.
hot gases. There is known a process in which the starting material is precipitated gels, this process providing not only `~;
agglomerated bodies having substantial macroporosity, but also a substantial level of mechanical solidity. However, if this ` 20 process is to lead to results which can be perfectly reproduced, on an industrial scale, it must be very closely monitored in all its phases, because of the unstable character of the pre-cipitated gels evolved under the influence of many factors.
It has now been found that another variety of alumina trihydrate, called bayerite, is capable, after dehydration in streams of hot gases, of giving particles of :,. '' . -.; . . .
.. . ... . .
,".,, ~ .
.`~, ','., ., . .. .:
` ~4~ ` ~
.. ~ .- ... .
:` ~ ''.:
: - `
686~;7 . . , a highly disorganized alumina, such particles being capable of setting by rehydration, thus giving a~ter activatlon, -agglomerated porous bodies which unexpectedly enjoy a particu-larly high level of solidity whlch is maintalned at elevated , 5 temperatures o~ the order of lOOO~C. It has also been found that bayerite imparts only a low degree o~ poroslty to the agglomeratea bo~ies produced but that, probably by virtue of the solidity which it imparts, it is possible to achieve the . ~ .
-' deslred modificatlons o~ pore characteristics~ in particular ; 10 as regards achieving macroporosity, without excesslvely impalrlng the mechanical cnaracterlstics o~ the bodies.
These pore modifications can be attained by the various pre-viously known processes reterrea to herein~e~ore, ~y other processes which are equally well known, namely varlous hydro-thermal treatments, an~ by the use, in conjunc~ion withbaye~rite, of other hydrated varieties of alumina which~are capable of imparting porosity to the bodies produced.
~;~ In additlon~ it is apparent that this high degree of .' !
solidity imparted by bayerite also makes it possible to pro-duce porous bo~les, by agglomeratlon, ~rom more compiex ;
compositions, by adding other components, in particular aluminas of various crystalline varieties WhlCh may or may ~` ~ not be treated in streams of hot gases, as well as zeolites `~ or~molecular sieves. In addition, these bodies may inclu~e elemen~s or compounds having catalytic actions of various kinds, in particular oxides and metals which have been added or whose precursors have ~een added, before treatment of the `::
`; alumina in a stream of hot gases, after such treatment, after ~rming o~ said bodies, or even to sodlum aluminate or to 3 aluminum salts, in order to produce therefrom precipitation .~ ~
`:
.. ., . :: ,. . ~
1C~6l366~
.-:
of alumina which is to be subjected to the action of the hot ::
gases. :;:
Accordingly, the present invention provides porous :
aluminous bodies having a resistance to crushing of from about . :
: .
. 2 kg to about 1~ kg; produced by humidification and agglomeration ;;;.
of compositions in powder form comprising at least 15% by weight ~ :~
~~ bayerite prepared by the action of hot gases on a hydrated :~
,;i alumina comprising bayerite said bayerite containing no more ::
than 10% by weight residual water which can be removed by high . ::
temperature calcination, from 0 to about 70% by weight of a ~ :
member selected from the group comprising cellulose, zeolites, , oxides and metals and the balance alumina, the agglomeration operation being followed by activation by calcination at a temperature of from about 600C to about 1,000C for a period of time from about 2 to 24 hours. .
The present invention also provides a process for pre- ~`
paring a porous aluminous body comprising: (1) preparing a . ~ ;
. partially dehydrated alumina having at least 15% by weight OI ^.
i bayerite, by treating a hydrated alumina in a stream of hot gases, : 20 said bayerite containing at most 10% by weight residual water ~..................................................................... .... .
, which can be removed by high temperature calcination; (2) mixing ; :
'~ with said partially dehydrated alumina from about 0 up to about :-.
. 70% by weight of a member selected from the group consisting of ; cellulose, zeolites, oxides and metals, and the balance addition- -:, ~.
,, - : . ~
.` al alumina provided that the resulting aluminous body contains .
~` at least 15% by weight bayerite; (3) shaping said mixture to the !'. ~ .
required dimension; and (4) calcining said mixture at a tempera- . :~
~ ture between 650C and about 1,000C for a period of time from ~:
,; . ' ' -. about 2 to about 24 hours.
In industrial practice, the various processes of forming by agglomeration can be used in the present case, -; :
particularly forming the substances into balls in a rotary ,....
1~68667 granulator, forming them into rings or cylinders by extrusion, or forming them by compression. The total process provides products whose properties are reproducible, which is obviously highly attractive from the industrial point of view.
i..................................................................... ...
,In practice, in order to obtain the most suitable highly disorganized aluminas from bayerite, it is preferable for it to be fairly completely dehydrated until the amount 'of residual water which can be removed by high-temperature calcination corresponds at most to 10% of their weight. In the case of treating complex mixtures of various hydrated varieties of alumina, it is obvious that, in order to achieve a sufficient degree of disorganization in the bayerite present, the water content of such mixtures, once treated, must be of the same order. It is no less obvious that, since the solidity o~ the agglomerated bodies produced is due to the dehydrated bayerite, the proportion thereof in the alumina or alumina-base compositions to be agglomerated must be sufficient, especially as the other components of such compositions provide . ~ .
less solidity by virtue of their presence and the bodies , 20 produced are highly porous. In practice, a proportion of at least 15% of partially dehydrated bayerite is preferable in the compositions to be agglomerated.
iGenerally, the conditions for producing hydrated ~ . .
`~aluminas which have a greater or lesser content of bayerite are known; for example, conventional processes comprise the :. ~
....
;
.
`'` ~`.
~ -6a-"~
1068667 ; ~
. ,.:: ` ..:
~ precipitation of alkaline aluminates or aluminum salts at . ~;temperatures whlcn are little higher than ordinary temperatures .
and at relatively high pH-values of approximately from 10 to :
, or, pre~era~ly, allowlng the evolution at the same pH-; 5 values of preclpitated gels with less elevated pEI-values. ~
; However., tne lengtn o~ tne evolutlon operations, the tempera- .
tures at which such operations occur, and various other con- ;
~: ditlons such ~s tne nature ana tne concentratlon o~ the :
reagents, modify the results obtained in such a way that the ::.
10 resulting products can vary wldely in composltlon krom tne ~ ;
. point o~ vlew of the amount of bayerite present and the nature "
.. : o~ the other varieties of hydrated alumina whlch are assoclatea . therewlth, wh1cn varieties can be amorphous, or crystallized ~ in the state of norstrandite, hydrargillite, or boehmite. ...
~ 15 ; In the ~ollowlng examples whlch are provided by ~
way of illustration, and not of limitat~on, the precipitates ; .
are produced elther ~rom sodlum alumlnate or from alumina sulphate, and brief information is glven thereln concer-ning . the condltlons as regards preclplta~lon ana tne composltlons ~:
20 of such precipitates. . .. :
In a first example, there is given the characterlstics .-ot balls proaucea with alsorganlze~ aluminas resulting from the treatment in streams of hot gas, of aluminas containing ~.
varying proportlons of bayerlte; tne followlng examples con- .
~: 25 cern balls, in which the macroporous volume has been increased "- by the addlt1on to the composltlons, materlals wnlcn can be ~. ~ .-~.~ rèmoved by calcination, balls produced from a mix~ure of . . ;
.~` alumina and molecular sieve; flnally, a last example snows tnat lt lS preferable to continue dehydration of the bayerite 3 to a sufficient extent, to obtain optimum results. .
~. - . ~'''''''''':
:. 7 .. :: .
,i ~ .
~68667 " ~:
EX~MPLE 1 ~his example is intended prlmarlly to snow ~ne ; relatlonsnlps ~e~ween the proportion of bayerite in aluminas which are su~sequently dehydrated in streams of hot gases, ana the mlcroporoslty or tne agglomerates produced by means of such dehydrated aluminas. In order to clearly show that the reduc~lon in microporoslty ls ~ue tO tne partlcular pro-perties of the bayerite, measurements are also taken of the microporosity of the inltlal alumlnas whlch are simply drled by atomization and then calcined at 500C, and of the micro-porosity of the alumlnas after dehy~ratlon but ~efore agglomeratlon, the microporosity of the agglomerated bodiès ~ produced and their total porosity.
:, ~ The varlous alumlnas su~jected to the experiment `' 15 are referred to hereina~ter by the Ietters A, B, C, D, E, F
~ and G, the processes ~r preparln~ same are summarlzea-below.
1.' . . .
`~ Alumina A - 15% of Bayerite A suspension o~ alumina gel, Wlth 50 g/l o~ alumlna 0 A1203 is prepared by precipitation, at 30C and at a constant `
20 pH-value of 8.7, of a solution of sodium aluminate, by means of a nitric acid solutlon. The suspenslon lS malntalned at the above temperature for 6 hours an~ then filtered, ànd the resultlng alumlna cake lS wasnea wltn aemlneralized water.
Water is added to the cake so as to re-~orm a suspenslon 25 which is sprayed ln gases at ~00C.
Alumlna B - 3~/o of Bayerlte --.: :
The process of preparing thls alumina is slmllar to that descrl~ed a~ove; preclpltatlon ls errected at 4~C
and at a pH-value of 10. The solution produced ~rom the 3 washed cake titrates 15~ g o~ alumlna per lltre ana lS sprayea ln gases at 4~0C.
`` ~~~ ''`
: :~L()6~667 Alumina C 50% of sayerite An amorpnous alumlna gel, produced by precipitatiOn at 25C and at a pH-value o~ 7.5 o~ sodlum aluminate wlth nitric acld, is progresslvely a~aed over a perlod o~ ~ hours , 5 to hydrated alumina containing 8~/o of bayerite whlch is moreover prepared in suspenslon in water; tne propor~lon lS .
. . .
. 3U% of hydrated alumina with 80% of bayerite for 70/0 o~
.'' J alumina gel, the two being calculated in the form A1203.
The mlxture lS left to evolve for 20 hours, and then it is filtered, and the resultlng cake is washed. Th~s cake is then re-suspen~ed, and then sprayed at 4500C.
Alumina D - 65% of Bayerite ~, The~same process as tnat usea tO proauce alumina '~ C i9 employed, except that the time allowea ~or evolution of : ~. -. : .
,, 15 the mixture is dl~erent, an~, in tnls example, lS 3~ hours.
Alumina E - 75% of Bayerite An alumina gel is preclpitated at 45C an~ at a pH-value or Y~, rrom sodlum aluminate and nitric acid. The . . .
gel is flltered, washed, then re-suspended in water at ordinary temperature. The suspenslon titrates 150 g/1 o aIumina A1203. After evolution or aging over a period of 2 days, the suspenslon is spraye~ at 4~C.
Alu _ a F -~80% of Bayer}te ~ -The same process as that used ~or proauclng alumlna E is employedj except that the time allowed for evalutlon o~
the suspension is di~ferent and in this example lS days~
Alumlna G - YU% o~ Bayerite !~ ' .. ' A solution of alumina sulphate is continuously preclpltate~ at a tempera~ure or 4uC and at a pH-value of 11, 3 by a sodium aluminate solution. The concentrations of the -' . , `..... ... :~ ' .
,,, ,~ g ,,. :, '` " ,.,' :.
~06~3667 solutlons are such that tne suspenslon proaucea tltrates ;. 50 g/1 of alumina A1203. After having been malntalned over a period of 12 hours at ordlnary temperature, tne suspenslon is filtered and washed and then the cake is re-suspended and sprayed in gases at 300C.
The dl~erent aluminas A, B, C, D, E, F and G
produced as above are partially dehydrated in streams of hot .;. gases so that the remainlng amounts O.t water wnlcn can ~e : ~ ;
` remove~ ~y high-temperature calcination are from 3 to 8%;
. 10 under these conditions the bayerlte lS no longer vlsl~1e by -X ray dlrrractlon.
.. . .
After humidification, the dehydrated aluminas are ~l made into the form of ba~ls with a dlameter o~ ~rom ~ to mm, ~y means or a rotary granulator, the granulation operation being followed by a maturing or aging operatlon in a drylng oven at a temperature or lU5C, ~or a period of 24 hours.
s :
A part of the balls produced is then calcined at :~ 650C:for a perlod of 2 hours, ror ~ne purposes of activa-tion, and another part is calcined at a temperature of `
:: 20 1000C ~or a perlod o~ 24 hours.
In order ~o show the or1gln of the microporosity (VmP) of the agglomerated products whlch are calcined at .~ 650C, microporoslty lS measured nol only on these products . :
but also on aluminas which have been partlally dehydrated in 25 streams of hot gases, and on alumlnas after spraylng an~ -".~ tnen calclnation at 500C. ~he microporoslty is measured .. .
~; by means of carbon tetrachlorlae. In additlon,.measurements ~ are made o~ the total porosities of the products which have .
'; been agglomerated and calcined at a tempera.ture of 650C, ~y ~ 3 means o~ a mercury porosimeter, and also the specific surface -;
'`'"' 10 '', ~
, ''~., '' . .
. areas of the partlally dehydratea aluminas and tho9e of the :: products which have been agglomerated and calclned at a temperature o~ 65~C. In aadltlon, tne reslstance to graln by graln crushing of the agglomerated products which have ::
been calcined at 650C, and that o~ tne agglomerate~ procuc~s wnlcn have ~een calcined at 1000C, are also measure~. : .
,, :
Table 1 summarizes the results obtalned.
.:
.. .
' .. :, ...
:' . ' '''' . . `: . :
~ 15 r ~ l I
5~,' . ~ .
~`~ ,. .
, ' ' ' :
~:, '. .. ',:. ': ' ' " :. "
' '.:' ~ .: :
'`': . ` ' ~ ~
. ' . .
- 20 ~: -~ ~ . . .... .
, ";, '.' ~ , ' .::- ~
.` ~ ',-''., ' '`'.: '',, ' '"` ~ ' `'' ` ' ''''.~ ' .~; '~ .
' 30 ~ :
A ' .~ ~ ~
.. '` ."~ "
, ~ ., ~D68667 ~ ~ .
... . .
. ~ :
Comparlson o~ these series o~ results clearly shows that tne mlcroporous volumes ot the balls resulting from ag-.. . .
glomeration o~ the varlous aluminas vary in the same way as ;l the microporous volumes or tne starting aluminas, in the same way as those of the dehydrated aluminas, and in the opposlte way to the ~ayerite con~ents or tne aluminas. However, the microporous volumes of the balls are much greater than those ;, of the aluminas, proba~ly ~ecause ~ne ~lsorganlzed alumina ~ ;
produced by dehydration is rehydrated after agglomeration, ` 10 giving crystals ln the ~orm o~ hlgnly porous feltlngs.
The lncrease in solidity with the bayerite content ;
` shows the attraction of the agglomerated bodles produced ~rom alumlnas WhiCh contain a sufficient proportion thereof.
The results a~ter calcination of the balls at 1~0C
for a perlo~ or 24 nours shows th~t the resistance to crushing is still satisfactory. -~-` This example concerns ~alls pro~ucea ~rom a mlx~ure ;
~ ~ :
o~ aluminas, one of which is made from a product which has a ?o hlgh bayerite content while the other lS ~rom an al~lmlna ge ` wnlcn nas no ~ayerite.
`~ ~he product which has no bayerite, produceq at a pH-value of about 8, primarily comprises pseudo-boehmite an~ amorphous phases. It is washed, sprayed and then dehydrated in a stream of hot gases so that the remalnlng ., ~ .
water wnlcn can ~e removed only at high temperature is 8~/o `.
of its weight~ Mixed with 68 kg of this dehydrated gel is 1~3 kg, calculated 1n tne torm A1203, of the dehydrated alu~
` mina D referred to in the preceding example, which con~alns 3 4% of its weight of water whlch can be removed at high `
.. ~.
` -13-..:
,, :, ~ ., , , . . .. .. : .
temperature. The mixture o~ the two aluminas is shaped into balls whose dlameter ls from 3 tO 4 mm, ~y means of a rotary granulator. The ~alls are then matured an~ then calcined at 65~C ana at lUUUC~ Measurements are taKen on these cal-5 cined balls of their specific surface area, microporosity,total porosity, and resistance to crusn1ng. The results are glven in the following table 2.
After calcination Aftër calcinatlon _ _ at 650C at 1000-C
Specifi~ surface ~ -area m /g 213 126 .. .
VmP cm~/g 0.73 U.70 .~ .
Total poroslty cm3/g 1.01 0.95 ~5 Resistance to crushlng kg 4.3 3.3 EX~MPLE 3 This example concerns balls whose total-pore vo-lume 20 is increased by the addition of a s~u~stance wh1ch can be ~ ~
rémovëd by thermal decomposition. ~ -The dehydrated alumina powder whlch is producea ~rom alumlna G (Example 1), almost solely comprising bayerite, is used. To a certaln welght o~ this re-crushed powder there is added lU, 1~ or 1~% o~sucn welgnt o~ wooa cellulose fibres sold under the Trade Mark "Solkafloc BW 4~".
The mixture is agglomerated in the ~orm o~ ~alls wltn a alameter or ~rom 3 to 4 mm, in a rotary granulator. ~ ;
After maturing in a damp atmosphere at 100C for 2 days, the 30 balls are arlea at 100C and then at 2UUC for a period of ~ ; ~
~' ' ', ., ' .
,`'':.''' ~.'.~:
:L06~3~;67 3 hours, and then calcined at 650C for a period of 2 hours. ~;~
The characterisitics of the balls produced are indicated in table 3 below.
Addition of Cellulose Fibres 10% 12% 15%
. _ . . .
Specific surface area m2/g 185 190 205 ~ ~
. : ... .',''' '. ' VmP cm3/g ~ 0.47 0.49 0.50 . . ":'.. .: -10Total porosity cm3/g 0.69 0.87 0.93 ~
.... .. , ~. '' Resistance to crushlng kg 52 2.1 ' ;':
This example shows that it is possible, starting from alumina in bayerite form, to produce agglomerates which enjoy substantial porosity, a substantial proportion of which comprises large pores, while being of sufficient mechanical strength.
This~example concerns molecular sieve-base balls.
A mixture of 30/O of dehydrated alumina G (Example 1), and 70/0 of dried 4 A molecular sieve is~crushed and then '-~
agglomerated in the form of balls in a rotary granulator.
~After maturingjin a damp atmos~phere at a temperature of 100C, the balls are activated;in a stream of hot air at a tempera~
ture of 450C. `~, The characteristics produced are as follows:
Specific surface area m2/g 120 VmP cm3/g 0.23 ~ -Total pore volume cm3/g 0.57 Resistance to crushing kg 7 ' .
.: :
.~ . .. . .
-15- ; ~
~L06~667 This.example shows the attraction of bayerite for producing mixed agglomerates of active alumina and molecular sieve, the adsorption characteristics of which are moreover quite particular.
Several portions of alumina G of Example 1 are dehydrated so that each portion does not contain more than 8, 10 and 15% of its weight of water which can be removed at high temperature. As in the preceding examples, balls which mea- -sure from 3 to 4 mm in diameter are produced, and are then dried and then calcined at 650C and at 1000C.
Table 4 below givesthe results obtained as regards the values of microporosity after c~lcination àt 65`0C and the values of the resistance to crushing after calcination at 650C
and at 1000C. ;
Residual amount of 10 15 water in %
Micropore volume in cm3/g .
: after calcination at 650C 0.42 0.3:g 0.35 .. _ (after calcina- : ï6 14 10 Resistance (tion at 650C _ . ::
t~ crushing(after calcina- 7 ~ 5~ ~ . : :
(tion at 1000C . . .
.: . .
: .
This example shows a marked reduction in tha solidity :~ -.,. . : .
25~ of the agglomerates:produced, with an amount of water which can.be extracted at high temperature which is 15% by weight, .
and consequently it is preferable to proceed fairly fàr with .;
dehydration of the aluminas by means of streams of hot gases.
:: ,, : :
.~ , . ::
~ ;
: -16~
'.''. ~'. ~':
''.' '".''''' ' ~ '"'" '" ~ ''': ' ' ,'''' '' ,''" ' '''' ' ' ' '' '
.,. ~
'~` ~'~
~ -3- -., ,~ .
... -- .. . . . . . .
. ,. . ~ . . ~. .
: : - : , .
~68667 with the desired specific surface area.
However, it is difficult to impart porosity comprising . ~ .
pores of large size, to bodies which are produced by the -~
agglomeration o particles of partially dehydrated hydrargillite. -~
Some processes make it possible to achieve this aim, in -~
! ( ' ' . ' particular regulating the amount of humidification water and ~ -.
using a very restricted range of grain sizes in respect of the particles. These processes are not without disadvantage; for example, the industrial production of a restricted range of grain sizes is always a fairly difficult problem to overcome, as is well known.
It is however possible to produce porous alumina bodies which ha~e macroporosity, by using hydrated aluminas : ,:
:1 which are different from hydrargillite, as the starting materials which are to be partially dehydrated in streams of --., ' . ' ':.
hot gases. There is known a process in which the starting material is precipitated gels, this process providing not only `~;
agglomerated bodies having substantial macroporosity, but also a substantial level of mechanical solidity. However, if this ` 20 process is to lead to results which can be perfectly reproduced, on an industrial scale, it must be very closely monitored in all its phases, because of the unstable character of the pre-cipitated gels evolved under the influence of many factors.
It has now been found that another variety of alumina trihydrate, called bayerite, is capable, after dehydration in streams of hot gases, of giving particles of :,. '' . -.; . . .
.. . ... . .
,".,, ~ .
.`~, ','., ., . .. .:
` ~4~ ` ~
.. ~ .- ... .
:` ~ ''.:
: - `
686~;7 . . , a highly disorganized alumina, such particles being capable of setting by rehydration, thus giving a~ter activatlon, -agglomerated porous bodies which unexpectedly enjoy a particu-larly high level of solidity whlch is maintalned at elevated , 5 temperatures o~ the order of lOOO~C. It has also been found that bayerite imparts only a low degree o~ poroslty to the agglomeratea bo~ies produced but that, probably by virtue of the solidity which it imparts, it is possible to achieve the . ~ .
-' deslred modificatlons o~ pore characteristics~ in particular ; 10 as regards achieving macroporosity, without excesslvely impalrlng the mechanical cnaracterlstics o~ the bodies.
These pore modifications can be attained by the various pre-viously known processes reterrea to herein~e~ore, ~y other processes which are equally well known, namely varlous hydro-thermal treatments, an~ by the use, in conjunc~ion withbaye~rite, of other hydrated varieties of alumina which~are capable of imparting porosity to the bodies produced.
~;~ In additlon~ it is apparent that this high degree of .' !
solidity imparted by bayerite also makes it possible to pro-duce porous bo~les, by agglomeratlon, ~rom more compiex ;
compositions, by adding other components, in particular aluminas of various crystalline varieties WhlCh may or may ~` ~ not be treated in streams of hot gases, as well as zeolites `~ or~molecular sieves. In addition, these bodies may inclu~e elemen~s or compounds having catalytic actions of various kinds, in particular oxides and metals which have been added or whose precursors have ~een added, before treatment of the `::
`; alumina in a stream of hot gases, after such treatment, after ~rming o~ said bodies, or even to sodlum aluminate or to 3 aluminum salts, in order to produce therefrom precipitation .~ ~
`:
.. ., . :: ,. . ~
1C~6l366~
.-:
of alumina which is to be subjected to the action of the hot ::
gases. :;:
Accordingly, the present invention provides porous :
aluminous bodies having a resistance to crushing of from about . :
: .
. 2 kg to about 1~ kg; produced by humidification and agglomeration ;;;.
of compositions in powder form comprising at least 15% by weight ~ :~
~~ bayerite prepared by the action of hot gases on a hydrated :~
,;i alumina comprising bayerite said bayerite containing no more ::
than 10% by weight residual water which can be removed by high . ::
temperature calcination, from 0 to about 70% by weight of a ~ :
member selected from the group comprising cellulose, zeolites, , oxides and metals and the balance alumina, the agglomeration operation being followed by activation by calcination at a temperature of from about 600C to about 1,000C for a period of time from about 2 to 24 hours. .
The present invention also provides a process for pre- ~`
paring a porous aluminous body comprising: (1) preparing a . ~ ;
. partially dehydrated alumina having at least 15% by weight OI ^.
i bayerite, by treating a hydrated alumina in a stream of hot gases, : 20 said bayerite containing at most 10% by weight residual water ~..................................................................... .... .
, which can be removed by high temperature calcination; (2) mixing ; :
'~ with said partially dehydrated alumina from about 0 up to about :-.
. 70% by weight of a member selected from the group consisting of ; cellulose, zeolites, oxides and metals, and the balance addition- -:, ~.
,, - : . ~
.` al alumina provided that the resulting aluminous body contains .
~` at least 15% by weight bayerite; (3) shaping said mixture to the !'. ~ .
required dimension; and (4) calcining said mixture at a tempera- . :~
~ ture between 650C and about 1,000C for a period of time from ~:
,; . ' ' -. about 2 to about 24 hours.
In industrial practice, the various processes of forming by agglomeration can be used in the present case, -; :
particularly forming the substances into balls in a rotary ,....
1~68667 granulator, forming them into rings or cylinders by extrusion, or forming them by compression. The total process provides products whose properties are reproducible, which is obviously highly attractive from the industrial point of view.
i..................................................................... ...
,In practice, in order to obtain the most suitable highly disorganized aluminas from bayerite, it is preferable for it to be fairly completely dehydrated until the amount 'of residual water which can be removed by high-temperature calcination corresponds at most to 10% of their weight. In the case of treating complex mixtures of various hydrated varieties of alumina, it is obvious that, in order to achieve a sufficient degree of disorganization in the bayerite present, the water content of such mixtures, once treated, must be of the same order. It is no less obvious that, since the solidity o~ the agglomerated bodies produced is due to the dehydrated bayerite, the proportion thereof in the alumina or alumina-base compositions to be agglomerated must be sufficient, especially as the other components of such compositions provide . ~ .
less solidity by virtue of their presence and the bodies , 20 produced are highly porous. In practice, a proportion of at least 15% of partially dehydrated bayerite is preferable in the compositions to be agglomerated.
iGenerally, the conditions for producing hydrated ~ . .
`~aluminas which have a greater or lesser content of bayerite are known; for example, conventional processes comprise the :. ~
....
;
.
`'` ~`.
~ -6a-"~
1068667 ; ~
. ,.:: ` ..:
~ precipitation of alkaline aluminates or aluminum salts at . ~;temperatures whlcn are little higher than ordinary temperatures .
and at relatively high pH-values of approximately from 10 to :
, or, pre~era~ly, allowlng the evolution at the same pH-; 5 values of preclpitated gels with less elevated pEI-values. ~
; However., tne lengtn o~ tne evolutlon operations, the tempera- .
tures at which such operations occur, and various other con- ;
~: ditlons such ~s tne nature ana tne concentratlon o~ the :
reagents, modify the results obtained in such a way that the ::.
10 resulting products can vary wldely in composltlon krom tne ~ ;
. point o~ vlew of the amount of bayerite present and the nature "
.. : o~ the other varieties of hydrated alumina whlch are assoclatea . therewlth, wh1cn varieties can be amorphous, or crystallized ~ in the state of norstrandite, hydrargillite, or boehmite. ...
~ 15 ; In the ~ollowlng examples whlch are provided by ~
way of illustration, and not of limitat~on, the precipitates ; .
are produced elther ~rom sodlum alumlnate or from alumina sulphate, and brief information is glven thereln concer-ning . the condltlons as regards preclplta~lon ana tne composltlons ~:
20 of such precipitates. . .. :
In a first example, there is given the characterlstics .-ot balls proaucea with alsorganlze~ aluminas resulting from the treatment in streams of hot gas, of aluminas containing ~.
varying proportlons of bayerlte; tne followlng examples con- .
~: 25 cern balls, in which the macroporous volume has been increased "- by the addlt1on to the composltlons, materlals wnlcn can be ~. ~ .-~.~ rèmoved by calcination, balls produced from a mix~ure of . . ;
.~` alumina and molecular sieve; flnally, a last example snows tnat lt lS preferable to continue dehydration of the bayerite 3 to a sufficient extent, to obtain optimum results. .
~. - . ~'''''''''':
:. 7 .. :: .
,i ~ .
~68667 " ~:
EX~MPLE 1 ~his example is intended prlmarlly to snow ~ne ; relatlonsnlps ~e~ween the proportion of bayerite in aluminas which are su~sequently dehydrated in streams of hot gases, ana the mlcroporoslty or tne agglomerates produced by means of such dehydrated aluminas. In order to clearly show that the reduc~lon in microporoslty ls ~ue tO tne partlcular pro-perties of the bayerite, measurements are also taken of the microporosity of the inltlal alumlnas whlch are simply drled by atomization and then calcined at 500C, and of the micro-porosity of the alumlnas after dehy~ratlon but ~efore agglomeratlon, the microporosity of the agglomerated bodiès ~ produced and their total porosity.
:, ~ The varlous alumlnas su~jected to the experiment `' 15 are referred to hereina~ter by the Ietters A, B, C, D, E, F
~ and G, the processes ~r preparln~ same are summarlzea-below.
1.' . . .
`~ Alumina A - 15% of Bayerite A suspension o~ alumina gel, Wlth 50 g/l o~ alumlna 0 A1203 is prepared by precipitation, at 30C and at a constant `
20 pH-value of 8.7, of a solution of sodium aluminate, by means of a nitric acid solutlon. The suspenslon lS malntalned at the above temperature for 6 hours an~ then filtered, ànd the resultlng alumlna cake lS wasnea wltn aemlneralized water.
Water is added to the cake so as to re-~orm a suspenslon 25 which is sprayed ln gases at ~00C.
Alumlna B - 3~/o of Bayerlte --.: :
The process of preparing thls alumina is slmllar to that descrl~ed a~ove; preclpltatlon ls errected at 4~C
and at a pH-value of 10. The solution produced ~rom the 3 washed cake titrates 15~ g o~ alumlna per lltre ana lS sprayea ln gases at 4~0C.
`` ~~~ ''`
: :~L()6~667 Alumina C 50% of sayerite An amorpnous alumlna gel, produced by precipitatiOn at 25C and at a pH-value o~ 7.5 o~ sodlum aluminate wlth nitric acld, is progresslvely a~aed over a perlod o~ ~ hours , 5 to hydrated alumina containing 8~/o of bayerite whlch is moreover prepared in suspenslon in water; tne propor~lon lS .
. . .
. 3U% of hydrated alumina with 80% of bayerite for 70/0 o~
.'' J alumina gel, the two being calculated in the form A1203.
The mlxture lS left to evolve for 20 hours, and then it is filtered, and the resultlng cake is washed. Th~s cake is then re-suspen~ed, and then sprayed at 4500C.
Alumina D - 65% of Bayerite ~, The~same process as tnat usea tO proauce alumina '~ C i9 employed, except that the time allowea ~or evolution of : ~. -. : .
,, 15 the mixture is dl~erent, an~, in tnls example, lS 3~ hours.
Alumina E - 75% of Bayerite An alumina gel is preclpitated at 45C an~ at a pH-value or Y~, rrom sodlum aluminate and nitric acid. The . . .
gel is flltered, washed, then re-suspended in water at ordinary temperature. The suspenslon titrates 150 g/1 o aIumina A1203. After evolution or aging over a period of 2 days, the suspenslon is spraye~ at 4~C.
Alu _ a F -~80% of Bayer}te ~ -The same process as that used ~or proauclng alumlna E is employedj except that the time allowed for evalutlon o~
the suspension is di~ferent and in this example lS days~
Alumlna G - YU% o~ Bayerite !~ ' .. ' A solution of alumina sulphate is continuously preclpltate~ at a tempera~ure or 4uC and at a pH-value of 11, 3 by a sodium aluminate solution. The concentrations of the -' . , `..... ... :~ ' .
,,, ,~ g ,,. :, '` " ,.,' :.
~06~3667 solutlons are such that tne suspenslon proaucea tltrates ;. 50 g/1 of alumina A1203. After having been malntalned over a period of 12 hours at ordlnary temperature, tne suspenslon is filtered and washed and then the cake is re-suspended and sprayed in gases at 300C.
The dl~erent aluminas A, B, C, D, E, F and G
produced as above are partially dehydrated in streams of hot .;. gases so that the remainlng amounts O.t water wnlcn can ~e : ~ ;
` remove~ ~y high-temperature calcination are from 3 to 8%;
. 10 under these conditions the bayerlte lS no longer vlsl~1e by -X ray dlrrractlon.
.. . .
After humidification, the dehydrated aluminas are ~l made into the form of ba~ls with a dlameter o~ ~rom ~ to mm, ~y means or a rotary granulator, the granulation operation being followed by a maturing or aging operatlon in a drylng oven at a temperature or lU5C, ~or a period of 24 hours.
s :
A part of the balls produced is then calcined at :~ 650C:for a perlod of 2 hours, ror ~ne purposes of activa-tion, and another part is calcined at a temperature of `
:: 20 1000C ~or a perlod o~ 24 hours.
In order ~o show the or1gln of the microporosity (VmP) of the agglomerated products whlch are calcined at .~ 650C, microporoslty lS measured nol only on these products . :
but also on aluminas which have been partlally dehydrated in 25 streams of hot gases, and on alumlnas after spraylng an~ -".~ tnen calclnation at 500C. ~he microporoslty is measured .. .
~; by means of carbon tetrachlorlae. In additlon,.measurements ~ are made o~ the total porosities of the products which have .
'; been agglomerated and calcined at a tempera.ture of 650C, ~y ~ 3 means o~ a mercury porosimeter, and also the specific surface -;
'`'"' 10 '', ~
, ''~., '' . .
. areas of the partlally dehydratea aluminas and tho9e of the :: products which have been agglomerated and calclned at a temperature o~ 65~C. In aadltlon, tne reslstance to graln by graln crushing of the agglomerated products which have ::
been calcined at 650C, and that o~ tne agglomerate~ procuc~s wnlcn have ~een calcined at 1000C, are also measure~. : .
,, :
Table 1 summarizes the results obtalned.
.:
.. .
' .. :, ...
:' . ' '''' . . `: . :
~ 15 r ~ l I
5~,' . ~ .
~`~ ,. .
, ' ' ' :
~:, '. .. ',:. ': ' ' " :. "
' '.:' ~ .: :
'`': . ` ' ~ ~
. ' . .
- 20 ~: -~ ~ . . .... .
, ";, '.' ~ , ' .::- ~
.` ~ ',-''., ' '`'.: '',, ' '"` ~ ' `'' ` ' ''''.~ ' .~; '~ .
' 30 ~ :
A ' .~ ~ ~
.. '` ."~ "
, ~ ., ~D68667 ~ ~ .
... . .
. ~ :
Comparlson o~ these series o~ results clearly shows that tne mlcroporous volumes ot the balls resulting from ag-.. . .
glomeration o~ the varlous aluminas vary in the same way as ;l the microporous volumes or tne starting aluminas, in the same way as those of the dehydrated aluminas, and in the opposlte way to the ~ayerite con~ents or tne aluminas. However, the microporous volumes of the balls are much greater than those ;, of the aluminas, proba~ly ~ecause ~ne ~lsorganlzed alumina ~ ;
produced by dehydration is rehydrated after agglomeration, ` 10 giving crystals ln the ~orm o~ hlgnly porous feltlngs.
The lncrease in solidity with the bayerite content ;
` shows the attraction of the agglomerated bodles produced ~rom alumlnas WhiCh contain a sufficient proportion thereof.
The results a~ter calcination of the balls at 1~0C
for a perlo~ or 24 nours shows th~t the resistance to crushing is still satisfactory. -~-` This example concerns ~alls pro~ucea ~rom a mlx~ure ;
~ ~ :
o~ aluminas, one of which is made from a product which has a ?o hlgh bayerite content while the other lS ~rom an al~lmlna ge ` wnlcn nas no ~ayerite.
`~ ~he product which has no bayerite, produceq at a pH-value of about 8, primarily comprises pseudo-boehmite an~ amorphous phases. It is washed, sprayed and then dehydrated in a stream of hot gases so that the remalnlng ., ~ .
water wnlcn can ~e removed only at high temperature is 8~/o `.
of its weight~ Mixed with 68 kg of this dehydrated gel is 1~3 kg, calculated 1n tne torm A1203, of the dehydrated alu~
` mina D referred to in the preceding example, which con~alns 3 4% of its weight of water whlch can be removed at high `
.. ~.
` -13-..:
,, :, ~ ., , , . . .. .. : .
temperature. The mixture o~ the two aluminas is shaped into balls whose dlameter ls from 3 tO 4 mm, ~y means of a rotary granulator. The ~alls are then matured an~ then calcined at 65~C ana at lUUUC~ Measurements are taKen on these cal-5 cined balls of their specific surface area, microporosity,total porosity, and resistance to crusn1ng. The results are glven in the following table 2.
After calcination Aftër calcinatlon _ _ at 650C at 1000-C
Specifi~ surface ~ -area m /g 213 126 .. .
VmP cm~/g 0.73 U.70 .~ .
Total poroslty cm3/g 1.01 0.95 ~5 Resistance to crushlng kg 4.3 3.3 EX~MPLE 3 This example concerns balls whose total-pore vo-lume 20 is increased by the addition of a s~u~stance wh1ch can be ~ ~
rémovëd by thermal decomposition. ~ -The dehydrated alumina powder whlch is producea ~rom alumlna G (Example 1), almost solely comprising bayerite, is used. To a certaln welght o~ this re-crushed powder there is added lU, 1~ or 1~% o~sucn welgnt o~ wooa cellulose fibres sold under the Trade Mark "Solkafloc BW 4~".
The mixture is agglomerated in the ~orm o~ ~alls wltn a alameter or ~rom 3 to 4 mm, in a rotary granulator. ~ ;
After maturing in a damp atmosphere at 100C for 2 days, the 30 balls are arlea at 100C and then at 2UUC for a period of ~ ; ~
~' ' ', ., ' .
,`'':.''' ~.'.~:
:L06~3~;67 3 hours, and then calcined at 650C for a period of 2 hours. ~;~
The characterisitics of the balls produced are indicated in table 3 below.
Addition of Cellulose Fibres 10% 12% 15%
. _ . . .
Specific surface area m2/g 185 190 205 ~ ~
. : ... .',''' '. ' VmP cm3/g ~ 0.47 0.49 0.50 . . ":'.. .: -10Total porosity cm3/g 0.69 0.87 0.93 ~
.... .. , ~. '' Resistance to crushlng kg 52 2.1 ' ;':
This example shows that it is possible, starting from alumina in bayerite form, to produce agglomerates which enjoy substantial porosity, a substantial proportion of which comprises large pores, while being of sufficient mechanical strength.
This~example concerns molecular sieve-base balls.
A mixture of 30/O of dehydrated alumina G (Example 1), and 70/0 of dried 4 A molecular sieve is~crushed and then '-~
agglomerated in the form of balls in a rotary granulator.
~After maturingjin a damp atmos~phere at a temperature of 100C, the balls are activated;in a stream of hot air at a tempera~
ture of 450C. `~, The characteristics produced are as follows:
Specific surface area m2/g 120 VmP cm3/g 0.23 ~ -Total pore volume cm3/g 0.57 Resistance to crushing kg 7 ' .
.: :
.~ . .. . .
-15- ; ~
~L06~667 This.example shows the attraction of bayerite for producing mixed agglomerates of active alumina and molecular sieve, the adsorption characteristics of which are moreover quite particular.
Several portions of alumina G of Example 1 are dehydrated so that each portion does not contain more than 8, 10 and 15% of its weight of water which can be removed at high temperature. As in the preceding examples, balls which mea- -sure from 3 to 4 mm in diameter are produced, and are then dried and then calcined at 650C and at 1000C.
Table 4 below givesthe results obtained as regards the values of microporosity after c~lcination àt 65`0C and the values of the resistance to crushing after calcination at 650C
and at 1000C. ;
Residual amount of 10 15 water in %
Micropore volume in cm3/g .
: after calcination at 650C 0.42 0.3:g 0.35 .. _ (after calcina- : ï6 14 10 Resistance (tion at 650C _ . ::
t~ crushing(after calcina- 7 ~ 5~ ~ . : :
(tion at 1000C . . .
.: . .
: .
This example shows a marked reduction in tha solidity :~ -.,. . : .
25~ of the agglomerates:produced, with an amount of water which can.be extracted at high temperature which is 15% by weight, .
and consequently it is preferable to proceed fairly fàr with .;
dehydration of the aluminas by means of streams of hot gases.
:: ,, : :
.~ , . ::
~ ;
: -16~
'.''. ~'. ~':
''.' '".''''' ' ~ '"'" '" ~ ''': ' ' ,'''' '' ,''" ' '''' ' ' ' '' '
Claims (5)
PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:
1. Porous aluminous bodies having a resistance to crushing of from about 2 kg to about 18 kg; produced by humidification and agglomeration of compositions in powder form comprising at least 15% by weight bayerite prepared by the action of hot gases on a hydrated alumina comprising bayerite said bayerite contain-ing no more than 10% by weight residual water which can be removed by high temperature calcination, from 0 to about 70%
by weight of a member selected from the group comprising cellu-lose, zeolites, oxides and metals and the balance alumina, the agglomeration operation being followed by activation by calcina-tion at a temperature of from about 600°C to about 1,000°C for a period of time from about 2 to 24 hours.
by weight of a member selected from the group comprising cellu-lose, zeolites, oxides and metals and the balance alumina, the agglomeration operation being followed by activation by calcina-tion at a temperature of from about 600°C to about 1,000°C for a period of time from about 2 to 24 hours.
2. A porous aluminous body according to claim 1 which contains a member of the group comprising cellulose, zeolites, oxides and metals.
3. A porous aluminous body according to claim 2 wherein said member of the group consisting of cellulose, zeolites, oxides and metals can be removed by calcination to impart macroporosity to said porous aluminous body.
4. A porous aluminous body according to claim 3 wherein said components selected from the group comprising cellulose, zeolites, oxides and metals have catalytic actions.
5. A process for preparing a porous aluminous body com-prising:
(1) preparing a partially dehydrated alumina having at least 15% by weight of bayerite, by treating a hydrated alumina in a stream of hot gases, said bayerite containing at most 10%
by weight residual water which can be removed by high temperature calcination;
(2) mixing with said partially dehydrated alumina from about 0 up to about 70% by weight of a member selected from the group consisting of cellulose, zeolites, oxides and metals, and the balance additional alumina provided that the resulting aluminous body contains at least 15% by weight bayerite;
(3) shaping said mixture to the required dimension; and (4) calcining said mixture at a temperature between 650°C
and about 1,000°C for a period of time from about 2 to about 24 hours.
(1) preparing a partially dehydrated alumina having at least 15% by weight of bayerite, by treating a hydrated alumina in a stream of hot gases, said bayerite containing at most 10%
by weight residual water which can be removed by high temperature calcination;
(2) mixing with said partially dehydrated alumina from about 0 up to about 70% by weight of a member selected from the group consisting of cellulose, zeolites, oxides and metals, and the balance additional alumina provided that the resulting aluminous body contains at least 15% by weight bayerite;
(3) shaping said mixture to the required dimension; and (4) calcining said mixture at a temperature between 650°C
and about 1,000°C for a period of time from about 2 to about 24 hours.
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| FR7401124A FR2324588A1 (en) | 1974-01-14 | 1974-01-14 | Porous alumina agglomerates for adsorption or catalysis - partly produced from bayerite for mechanical strength |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1068667A true CA1068667A (en) | 1979-12-25 |
Family
ID=9133429
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA217,778A Expired CA1068667A (en) | 1974-01-14 | 1975-01-13 | Porous aluminous bodies produced by agglomeration of powders |
Country Status (9)
| Country | Link |
|---|---|
| JP (1) | JPS5612250B2 (en) |
| BE (1) | BE824275A (en) |
| CA (1) | CA1068667A (en) |
| DE (1) | DE2501056B2 (en) |
| ES (1) | ES433761A1 (en) |
| FR (1) | FR2324588A1 (en) |
| IT (1) | IT1026320B (en) |
| NL (1) | NL7500400A (en) |
| SE (1) | SE7500324L (en) |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US7632773B2 (en) | 2007-01-04 | 2009-12-15 | Headwaters Technology Innovation, Llc | Methods for manufacturing supported catalyst from a porous support and a nanocatalyst solution |
Families Citing this family (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| DE102012215878A1 (en) * | 2012-09-07 | 2014-03-13 | Robert Bosch Gmbh | Electrode and method for manufacturing an electrode |
Family Cites Families (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS4998398A (en) * | 1973-01-26 | 1974-09-18 | ||
| FR2221405B1 (en) * | 1973-03-14 | 1984-02-24 | Rhone Poulenc Spec Chim |
-
1974
- 1974-01-14 FR FR7401124A patent/FR2324588A1/en active Granted
-
1975
- 1975-01-10 BE BE152281A patent/BE824275A/en not_active IP Right Cessation
- 1975-01-13 SE SE7500324A patent/SE7500324L/xx unknown
- 1975-01-13 ES ES433761A patent/ES433761A1/en not_active Expired
- 1975-01-13 IT IT47648/75A patent/IT1026320B/en active
- 1975-01-13 CA CA217,778A patent/CA1068667A/en not_active Expired
- 1975-01-13 DE DE2501056A patent/DE2501056B2/en not_active Withdrawn
- 1975-01-14 NL NL7500400A patent/NL7500400A/en unknown
- 1975-01-14 JP JP692775A patent/JPS5612250B2/ja not_active Expired
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US7632773B2 (en) | 2007-01-04 | 2009-12-15 | Headwaters Technology Innovation, Llc | Methods for manufacturing supported catalyst from a porous support and a nanocatalyst solution |
Also Published As
| Publication number | Publication date |
|---|---|
| FR2324588A1 (en) | 1977-04-15 |
| FR2324588B1 (en) | 1981-01-09 |
| IT1026320B (en) | 1978-09-20 |
| ES433761A1 (en) | 1976-12-16 |
| SE7500324L (en) | 1975-07-15 |
| JPS50117697A (en) | 1975-09-13 |
| JPS5612250B2 (en) | 1981-03-19 |
| NL7500400A (en) | 1975-07-16 |
| DE2501056A1 (en) | 1975-07-17 |
| BE824275A (en) | 1975-07-10 |
| DE2501056B2 (en) | 1979-11-29 |
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