CA1078878A - Process of catalytic methanation - Google Patents
Process of catalytic methanationInfo
- Publication number
- CA1078878A CA1078878A CA250,363A CA250363A CA1078878A CA 1078878 A CA1078878 A CA 1078878A CA 250363 A CA250363 A CA 250363A CA 1078878 A CA1078878 A CA 1078878A
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- CA
- Canada
- Prior art keywords
- accordance
- nickel
- serpentine
- carbon
- catalyst
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
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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
- B01J21/00—Catalysts comprising the elements, oxides, or hydroxides of magnesium, boron, aluminium, carbon, silicon, titanium, zirconium, or hafnium
- B01J21/16—Clays or other mineral silicates
-
- 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
- B01J23/00—Catalysts comprising metals or metal oxides or hydroxides, not provided for in group B01J21/00
- B01J23/70—Catalysts comprising metals or metal oxides or hydroxides, not provided for in group B01J21/00 of the iron group metals or copper
- B01J23/74—Iron group metals
- B01J23/755—Nickel
-
- 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
- B01J23/00—Catalysts comprising metals or metal oxides or hydroxides, not provided for in group B01J21/00
- B01J23/70—Catalysts comprising metals or metal oxides or hydroxides, not provided for in group B01J21/00 of the iron group metals or copper
- B01J23/76—Catalysts comprising metals or metal oxides or hydroxides, not provided for in group B01J21/00 of the iron group metals or copper combined with metals, oxides or hydroxides provided for in groups B01J23/02 - B01J23/36
- B01J23/80—Catalysts comprising metals or metal oxides or hydroxides, not provided for in group B01J21/00 of the iron group metals or copper combined with metals, oxides or hydroxides provided for in groups B01J23/02 - B01J23/36 with zinc, cadmium or mercury
-
- 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
- B01J23/00—Catalysts comprising metals or metal oxides or hydroxides, not provided for in group B01J21/00
- B01J23/70—Catalysts comprising metals or metal oxides or hydroxides, not provided for in group B01J21/00 of the iron group metals or copper
- B01J23/76—Catalysts comprising metals or metal oxides or hydroxides, not provided for in group B01J21/00 of the iron group metals or copper combined with metals, oxides or hydroxides provided for in groups B01J23/02 - B01J23/36
- B01J23/84—Catalysts comprising metals or metal oxides or hydroxides, not provided for in group B01J21/00 of the iron group metals or copper combined with metals, oxides or hydroxides provided for in groups B01J23/02 - B01J23/36 with arsenic, antimony, bismuth, vanadium, niobium, tantalum, polonium, chromium, molybdenum, tungsten, manganese, technetium or rhenium
-
- C—CHEMISTRY; METALLURGY
- C07—ORGANIC CHEMISTRY
- C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
- C07C1/00—Preparation of hydrocarbons from one or more compounds, none of them being a hydrocarbon
- C07C1/02—Preparation of hydrocarbons from one or more compounds, none of them being a hydrocarbon from oxides of a carbon
-
- C—CHEMISTRY; METALLURGY
- C07—ORGANIC CHEMISTRY
- C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
- C07C2521/00—Catalysts comprising the elements, oxides or hydroxides of magnesium, boron, aluminium, carbon, silicon, titanium, zirconium or hafnium
- C07C2521/16—Clays or other mineral silicates
-
- C—CHEMISTRY; METALLURGY
- C07—ORGANIC CHEMISTRY
- C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
- C07C2523/00—Catalysts comprising metals or metal oxides or hydroxides, not provided for in group C07C2521/00
- C07C2523/70—Catalysts comprising metals or metal oxides or hydroxides, not provided for in group C07C2521/00 of the iron group metals or copper
- C07C2523/74—Iron group metals
- C07C2523/755—Nickel
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- Chemical & Material Sciences (AREA)
- Organic Chemistry (AREA)
- Engineering & Computer Science (AREA)
- Chemical Kinetics & Catalysis (AREA)
- Materials Engineering (AREA)
- General Chemical & Material Sciences (AREA)
- Oil, Petroleum & Natural Gas (AREA)
- Dispersion Chemistry (AREA)
- Catalysts (AREA)
- Organic Low-Molecular-Weight Compounds And Preparation Thereof (AREA)
- Silicates, Zeolites, And Molecular Sieves (AREA)
- Low-Molecular Organic Synthesis Reactions Using Catalysts (AREA)
Abstract
PROCESS OF CATALYTIC METHANATION
of which the following is a specification:
Abstract of the Disclosure Methanation of carbon oxides such as carbon monoxide and carbon dioxide with hydrogen to produce methane is carried out with the aid of a heated catalyst which is the calcination product of a serpentine containing nickel and optionally mag-nesium and other elements together with silicon in the essentially laminar nickel serpentine. The catalysts exhibit good conversion at relatively low temperatures, are relatively insensitive to high temperature excursions, and have an extended life.
of which the following is a specification:
Abstract of the Disclosure Methanation of carbon oxides such as carbon monoxide and carbon dioxide with hydrogen to produce methane is carried out with the aid of a heated catalyst which is the calcination product of a serpentine containing nickel and optionally mag-nesium and other elements together with silicon in the essentially laminar nickel serpentine. The catalysts exhibit good conversion at relatively low temperatures, are relatively insensitive to high temperature excursions, and have an extended life.
Description
~~~
8~37~3 This invention relates to th~ methanation of oxides of carbon to produae methane by a procedure utilizing a novel catalyst for this reaction. More particularly, it relates to the utilization of certain heavy metal substituted ser-pentines as precursors of finished catalysts whereby the reaction between ~xides of carbon such as carbon monoxide and carbon dioxide with hydrogen to produce methane may be carried out under especiallly favorable process conditions, ;~
including but not limited to high conversion rates, low con-version temperatures, long catalyst life, and relatively insen-sitivity of the catalyst to high temperature excursions.
The production of methane from oxides of carbon by a catalytic route has been known since 1902, and has been employed to a certain extent in the intervening years. How-ever, with the current shortage of all forms of energy, the reaction has achieved great importance, inasmuch as it pro-mises a solution to the shortage of natural gas by enabling coal, lignite, and petroleum fractions and residues not other-wise readily utilizable to serve as the ultimate source of the carbon oxides which are reacted with hydrogen to form methane (and water as the pr~ncipal secondary product).
The reaction concerned is commonly called methanation, and a vast literature exists on the subject extending back nearly to the commencement of the present century. Useful articles ~-are Chapters 1 and 6 on pages 1-27 and 473-511 respectively of Volume IV of the series entitled "Catalysis", edited by Paul H. Emmett, New York, Reinhold, 1956. More recent reviews showing in addition the overall process commencing with coal or naptha, may be found in the journal Hydrocarbon Processing, April, 1973, pages 117 through 125; and The Oil and Gas Journal, June 25, 1973, pages 107-134. Another useful paper is Catalysis Reviews 8 [2] 159-210 (1973).
8~37~3 This invention relates to th~ methanation of oxides of carbon to produae methane by a procedure utilizing a novel catalyst for this reaction. More particularly, it relates to the utilization of certain heavy metal substituted ser-pentines as precursors of finished catalysts whereby the reaction between ~xides of carbon such as carbon monoxide and carbon dioxide with hydrogen to produce methane may be carried out under especiallly favorable process conditions, ;~
including but not limited to high conversion rates, low con-version temperatures, long catalyst life, and relatively insen-sitivity of the catalyst to high temperature excursions.
The production of methane from oxides of carbon by a catalytic route has been known since 1902, and has been employed to a certain extent in the intervening years. How-ever, with the current shortage of all forms of energy, the reaction has achieved great importance, inasmuch as it pro-mises a solution to the shortage of natural gas by enabling coal, lignite, and petroleum fractions and residues not other-wise readily utilizable to serve as the ultimate source of the carbon oxides which are reacted with hydrogen to form methane (and water as the pr~ncipal secondary product).
The reaction concerned is commonly called methanation, and a vast literature exists on the subject extending back nearly to the commencement of the present century. Useful articles ~-are Chapters 1 and 6 on pages 1-27 and 473-511 respectively of Volume IV of the series entitled "Catalysis", edited by Paul H. Emmett, New York, Reinhold, 1956. More recent reviews showing in addition the overall process commencing with coal or naptha, may be found in the journal Hydrocarbon Processing, April, 1973, pages 117 through 125; and The Oil and Gas Journal, June 25, 1973, pages 107-134. Another useful paper is Catalysis Reviews 8 [2] 159-210 (1973).
- 2 -... . . .. . . . .
~7~3878 The present invention deals with the final catalyzed reaction in such composite processes to obtain methane from low grade raw materials. It also finds utility wherever carbon oxides are to be converred to methane, as for example in the purification of synthesis gas where the impurities consist of carbon monoxide or carbon dioxide or mixtures of the two.
According to the invention there is provided in a process wherein a carbon oxide is catalytically hydrogen-ated so as to form methane by passing said carbon oxide together with hydrogen over a heated catalyst, the improvement which comprises utilizing as said catalyst an amorphous nickel silicate resulting from the calcination and reduction of a nickel serpentine having a chemical composition represented by the following:
( y gM6_y_g) (RhSi4-h) 10 (H~F)8; wherein M is Mg, Co , Fe , Cu , Mn , Zn , or mixtures thereo;
R is Al, Cr , or mixtures thereof;
Zn ' 4, Cu < 0.5, Mn ' 0.5, g + h = 2x O ' x ' 0.1; 0.5 ' y ' 6; and wherein the first parenthesis shows the cations in the octahedral layer and the second parenthesis shows the -cations in the tetrahedral layer; and wherein from zero to two fluoride ions may be present for a total of eight hydroxide plus fluoride; this precursor nickel serpentine prior to calcining being a 1:1 trioctahedral phyllo-silicate in general having a substantially balanced framework, from the standpoint of total charge, with no exchangeable ions needed for neutrality, said calcination and reduction being carried out at a temperature of about ~ - 3 -97~3~37~
500C to about 900C and for a time sufficient to destroy the crystallinity of the precursor nickel serpentine and produce said amorphous nickel silicate, and reduction being performed in the presence of hydrogen.
- 3a -B
078~378 In general, and in the "ideal" serpentine, g ~ h ~v~, so that the first llne o~ the formula reduces to:
~ Nl R M6 y x) (Rxsi4-x) 1 8 [la]
Since x is at most about one-fortleth of the silicon present (on an atomic basis) and at most about one-slxtieth o~ the combined nickel and M atom~, it will be clear that the distrlbutlon of x as between g and h requires highly exactlng structural determinations. On the other hand, the gross con-tent Or Sl, Nl, M and R, as well as Or the remaining elements, can be readily determined by standard chemical methods; and like-wise the a, bJ and c 13ttice parameters discu~sed below can be readily determined by standard x-ray di~rraction methods, ~o that the correspondence or non-correspondence o~ a given preparation or mineral speclmen to Formula [1] can eisily be determined without separately determlning g and h, particularly since their sum, 2x, readily rOllOw rrom the standard chemical and x-ray investigations just mentioned.
An alternative rormulation, which upon mere inspection will be seen to be cornpletely equivalent to the ~oregoing [1], is that the chemical composltion corresponds to one o~ the two end members shown below or to any composition intermediate there-between, viz:
Y 2x 6-y_2x) (Si4) 10 (HJF)8 [lbJ
and ~ NiyM6_y) (R2XS14-2X) 10 ( 8 [lc]
all of the other restralnts shown rOr [1] of course applylng. -- !
.~ typical and indeed expected intermediate composition between end members, ~lb] and [ lC] appe~rs herelnabove as [la~.
~ 7~7~3 :
As is known, nickel serpentines are ph~llosilicates, that is, silicates with a laminar habit, exhibiting a basal spacingl i.e., a c spacing, approximately 7 A. The a spacing is about 5.3A, or a multiple thereof, while the b spacing is a~out 9.2 or 9. 3A. Moreover, they are silicates of the so-called 1:1 type, having one octahedral layer bonded to an adjacent tetrahedral layer by the sharing of oxygen ions.
Moreover, the structure is trioctahedrali that is, all of the possible sites for positive ions in the octahedral layer are occupied, in contrast to the so-called dioctahedral structures of some other p~yllosilicates in which only 2/3 of such sites are filled. Furthermore, each individual 1:1 sheet is elec-trostatically substantially neutral, with as many positive ions as negative ions within the combined 1:1 layer structure.
This is in contrast to electrostatically unbalanced silicates, such as zeolites and smectites, which require cations exterior to the silicate framework in order to achieve electrostatic neutrality. Those knowledgeable in clay chemistry will of course recognize that some ion-exchange capacity is generated by broken bonds at the edges of the crystallites even in balanced layers, as evidenced for example by kaolinite and attapulgite.
A good discussion of serpentines (including nickel serpentines) occurs in the chapter by that name on pages 170-190 of the text "Rock-Forming Minerals", volume 3, Sheet Silicates, by W. A. Deer et al., London, 1962. Nomenclature for this group varies somewhat; Brindley in the text, "The X-Ray Idè~tification and Crystal Structures of Clay Minerals", G. Brown, Ed., London, 1961, pages 109-131, adopts the term "nickel serpentine". French workers prefer "nickeliforous ~ - 5 -.
- . .. . : . . ,.. - : - ~
887~
antigorite", as described, for example, on pages 180-193 of the text "Minéralogie des Argiles", by Simonne Caillère et al., Paris, 1963.
- 5a -': -:
~078878 Nlckel serlentine~ withln the sco~e of the invention occur in a number Or localltles throughout the world, some in quallty and quantlty Or such a nature to be commerci31. The nlckel ores Or New Caledonla are l~rgely nickel serpentlnes J
and indlvldual species thereof have been called nepoulte, noumeite, ~nd others. Another well-known deposlt occurs near Rlddle, Oregon, and h~s been generally identlfled as garnlerite. Ty~lcal analyses of the New C~ledonian and Oregonian nickel serpentines are given in U.S. Geological Survey Bulletln No. 770, 1924J
p. 712. It wlll be re~dily understood thflt ~11 mlnerals which m~y be termed nickel serpentines may not necess3rily have a com-position coming wlthin the scope Or formul~ [1] set rorth herein above; an analysis dnd inspection wlll of course settle the point in any glven case.
In a~dltlon to naturally occuring nickel serpentines, a vast llterature, both scienti~lc and patent, exlst~ dlscloslng varlous methods for syntheslzlng nickel serpentines, and more-over, for synthesizing nickel serpentines within the scope of the invention provided that the startlng materials and processlng condltions are such th~t ~ synthesized product colnlng wlthln the scope Or formul3 [1~ result~.
Svme Or the r-elevant llterature of thls type comprlses the ~ollowing ~rtlcles:
. .
7887~3 C.R. Acad. Sci. P~ris, Serie C 264 [18] 1536-8 (1967) Mlrtin, G.A., et al.
Sur la ~reparation et la structure de l'antlgorite et de la montmorillonite de nickel.
Ibid., 225, 869-72 (1947) Lon~uet, J., et al.
Synthese de silicates de nickel, magne~ium et cobalt~
presentant des structures du type kaollnite-antigorite.
Ibid., 239~ 1535-1537 ~1954) Caillere, S., et al.
Synthese de~ quelques phyllites nickellrere~.
Ibld. J 241, 810-812 (1955) Caillere, ~., et al.
Inrluence de la temperature . . ~ormation de l'antigorlte nickelirere.
Ibid., Serie C 267, 610-613 (1968) Dalmon, A., et al.
Sur la preparation et la structure des silicates basiques de cobalt et de magnesium du type talc et antlgorite.
Journal de Chemie Ph~si~ue et de Physicochimie Biolo~ique 67 (b) 1149-60 (1970) Martin, G.A., et ~l.
Synthese du talc et de l'antigorite de nickel, etude de leur decompositlon thermlque et de leur reduction en vue d'obtenir des catalyseurs de nickel sur silice.
Helv. Chlm. Acta 25 1543-47 (1942) Feitknecht, W , et al.
~ber die Bildung eines Nickel- und Kobaltslllcates mit Schichtengitter N3turwissen~cha~ten 39, 233-34, ~1952) Noll, W., et al.
Synthese des Garnlerites 781!37~3 .~merican Mineralo~ist 39: 957-75, (lgs4) ROYJ Della M,, et al.
An Experimental Study o~ the Formatinn and Pro~)erties Or Synthetic Serpentlne~ and Related Layer Silicate Mlnerals, Clay Minerals Bulletin, 5, ~no,30~ 272-278 (1963) Caillere, S., et al.
Nouvelles Etudes sur la Synthese de~ Mlnerzux Argileux a ~artir de gels.
Trans. 4th Intern. Congr, Soil_Scl., Amsterdam 3, 34-37;
Franzen, P., et al.
O Synthesis Or Nlckel Hydrosilicates Bull. Grp. ~ranc, Ar~iles 7, ~2] 21-30 (1956) Caillere, S., et al.
Etude de Quelques Silicates Nickéli~eres Naturels et de Synthese Contr. Mineral and Petrol. 34 84-86 (1972) Jasmund K., et al.
Synthesisor Mg^ and Ni-Antigorite Ibid,, 34 346 (1972) Jasmund, K,, et al.
Synthesis Or Mg- and Ni-Antigorite: A Correctlon Beitrage zur Mineralogie und Petrographie ~, 232-241 (1960) Noll, l~., et al.
Ueber synthetischen Kobaltchrysotil und seine Beziehun~en usw.
Bul. Soc. Franc. Miner. Crist. 79, 408-420 (1956) Caillere, S,, et al.
i Étude Exper~mentale du mécanisme de la rormation des antigorites nickelifères. , Kolloid-Zeitschrlft ~ 11 (1958) NO11J W., et al.
Adsorptionsvermoegen und spezi~ische Oberflaeche von Silikaten mit roehrenfoermig gebauten Primaerkristallen.
~ 7~3878 Typical o~ the patent llterature containlng procedure~
~or gynthesizing nickel serpentines and other so-called nickel serpentine minerals are the ~ollowlng:
u.s. 2,658,875 Schuit~ et al., November 10, 1953 53,686J341 Eberly August 22, 1972
~7~3878 The present invention deals with the final catalyzed reaction in such composite processes to obtain methane from low grade raw materials. It also finds utility wherever carbon oxides are to be converred to methane, as for example in the purification of synthesis gas where the impurities consist of carbon monoxide or carbon dioxide or mixtures of the two.
According to the invention there is provided in a process wherein a carbon oxide is catalytically hydrogen-ated so as to form methane by passing said carbon oxide together with hydrogen over a heated catalyst, the improvement which comprises utilizing as said catalyst an amorphous nickel silicate resulting from the calcination and reduction of a nickel serpentine having a chemical composition represented by the following:
( y gM6_y_g) (RhSi4-h) 10 (H~F)8; wherein M is Mg, Co , Fe , Cu , Mn , Zn , or mixtures thereo;
R is Al, Cr , or mixtures thereof;
Zn ' 4, Cu < 0.5, Mn ' 0.5, g + h = 2x O ' x ' 0.1; 0.5 ' y ' 6; and wherein the first parenthesis shows the cations in the octahedral layer and the second parenthesis shows the -cations in the tetrahedral layer; and wherein from zero to two fluoride ions may be present for a total of eight hydroxide plus fluoride; this precursor nickel serpentine prior to calcining being a 1:1 trioctahedral phyllo-silicate in general having a substantially balanced framework, from the standpoint of total charge, with no exchangeable ions needed for neutrality, said calcination and reduction being carried out at a temperature of about ~ - 3 -97~3~37~
500C to about 900C and for a time sufficient to destroy the crystallinity of the precursor nickel serpentine and produce said amorphous nickel silicate, and reduction being performed in the presence of hydrogen.
- 3a -B
078~378 In general, and in the "ideal" serpentine, g ~ h ~v~, so that the first llne o~ the formula reduces to:
~ Nl R M6 y x) (Rxsi4-x) 1 8 [la]
Since x is at most about one-fortleth of the silicon present (on an atomic basis) and at most about one-slxtieth o~ the combined nickel and M atom~, it will be clear that the distrlbutlon of x as between g and h requires highly exactlng structural determinations. On the other hand, the gross con-tent Or Sl, Nl, M and R, as well as Or the remaining elements, can be readily determined by standard chemical methods; and like-wise the a, bJ and c 13ttice parameters discu~sed below can be readily determined by standard x-ray di~rraction methods, ~o that the correspondence or non-correspondence o~ a given preparation or mineral speclmen to Formula [1] can eisily be determined without separately determlning g and h, particularly since their sum, 2x, readily rOllOw rrom the standard chemical and x-ray investigations just mentioned.
An alternative rormulation, which upon mere inspection will be seen to be cornpletely equivalent to the ~oregoing [1], is that the chemical composltion corresponds to one o~ the two end members shown below or to any composition intermediate there-between, viz:
Y 2x 6-y_2x) (Si4) 10 (HJF)8 [lbJ
and ~ NiyM6_y) (R2XS14-2X) 10 ( 8 [lc]
all of the other restralnts shown rOr [1] of course applylng. -- !
.~ typical and indeed expected intermediate composition between end members, ~lb] and [ lC] appe~rs herelnabove as [la~.
~ 7~7~3 :
As is known, nickel serpentines are ph~llosilicates, that is, silicates with a laminar habit, exhibiting a basal spacingl i.e., a c spacing, approximately 7 A. The a spacing is about 5.3A, or a multiple thereof, while the b spacing is a~out 9.2 or 9. 3A. Moreover, they are silicates of the so-called 1:1 type, having one octahedral layer bonded to an adjacent tetrahedral layer by the sharing of oxygen ions.
Moreover, the structure is trioctahedrali that is, all of the possible sites for positive ions in the octahedral layer are occupied, in contrast to the so-called dioctahedral structures of some other p~yllosilicates in which only 2/3 of such sites are filled. Furthermore, each individual 1:1 sheet is elec-trostatically substantially neutral, with as many positive ions as negative ions within the combined 1:1 layer structure.
This is in contrast to electrostatically unbalanced silicates, such as zeolites and smectites, which require cations exterior to the silicate framework in order to achieve electrostatic neutrality. Those knowledgeable in clay chemistry will of course recognize that some ion-exchange capacity is generated by broken bonds at the edges of the crystallites even in balanced layers, as evidenced for example by kaolinite and attapulgite.
A good discussion of serpentines (including nickel serpentines) occurs in the chapter by that name on pages 170-190 of the text "Rock-Forming Minerals", volume 3, Sheet Silicates, by W. A. Deer et al., London, 1962. Nomenclature for this group varies somewhat; Brindley in the text, "The X-Ray Idè~tification and Crystal Structures of Clay Minerals", G. Brown, Ed., London, 1961, pages 109-131, adopts the term "nickel serpentine". French workers prefer "nickeliforous ~ - 5 -.
- . .. . : . . ,.. - : - ~
887~
antigorite", as described, for example, on pages 180-193 of the text "Minéralogie des Argiles", by Simonne Caillère et al., Paris, 1963.
- 5a -': -:
~078878 Nlckel serlentine~ withln the sco~e of the invention occur in a number Or localltles throughout the world, some in quallty and quantlty Or such a nature to be commerci31. The nlckel ores Or New Caledonla are l~rgely nickel serpentlnes J
and indlvldual species thereof have been called nepoulte, noumeite, ~nd others. Another well-known deposlt occurs near Rlddle, Oregon, and h~s been generally identlfled as garnlerite. Ty~lcal analyses of the New C~ledonian and Oregonian nickel serpentines are given in U.S. Geological Survey Bulletln No. 770, 1924J
p. 712. It wlll be re~dily understood thflt ~11 mlnerals which m~y be termed nickel serpentines may not necess3rily have a com-position coming wlthin the scope Or formul~ [1] set rorth herein above; an analysis dnd inspection wlll of course settle the point in any glven case.
In a~dltlon to naturally occuring nickel serpentines, a vast llterature, both scienti~lc and patent, exlst~ dlscloslng varlous methods for syntheslzlng nickel serpentines, and more-over, for synthesizing nickel serpentines within the scope of the invention provided that the startlng materials and processlng condltions are such th~t ~ synthesized product colnlng wlthln the scope Or formul3 [1~ result~.
Svme Or the r-elevant llterature of thls type comprlses the ~ollowing ~rtlcles:
. .
7887~3 C.R. Acad. Sci. P~ris, Serie C 264 [18] 1536-8 (1967) Mlrtin, G.A., et al.
Sur la ~reparation et la structure de l'antlgorite et de la montmorillonite de nickel.
Ibid., 225, 869-72 (1947) Lon~uet, J., et al.
Synthese de silicates de nickel, magne~ium et cobalt~
presentant des structures du type kaollnite-antigorite.
Ibid., 239~ 1535-1537 ~1954) Caillere, S., et al.
Synthese de~ quelques phyllites nickellrere~.
Ibld. J 241, 810-812 (1955) Caillere, ~., et al.
Inrluence de la temperature . . ~ormation de l'antigorlte nickelirere.
Ibid., Serie C 267, 610-613 (1968) Dalmon, A., et al.
Sur la preparation et la structure des silicates basiques de cobalt et de magnesium du type talc et antlgorite.
Journal de Chemie Ph~si~ue et de Physicochimie Biolo~ique 67 (b) 1149-60 (1970) Martin, G.A., et ~l.
Synthese du talc et de l'antigorite de nickel, etude de leur decompositlon thermlque et de leur reduction en vue d'obtenir des catalyseurs de nickel sur silice.
Helv. Chlm. Acta 25 1543-47 (1942) Feitknecht, W , et al.
~ber die Bildung eines Nickel- und Kobaltslllcates mit Schichtengitter N3turwissen~cha~ten 39, 233-34, ~1952) Noll, W., et al.
Synthese des Garnlerites 781!37~3 .~merican Mineralo~ist 39: 957-75, (lgs4) ROYJ Della M,, et al.
An Experimental Study o~ the Formatinn and Pro~)erties Or Synthetic Serpentlne~ and Related Layer Silicate Mlnerals, Clay Minerals Bulletin, 5, ~no,30~ 272-278 (1963) Caillere, S., et al.
Nouvelles Etudes sur la Synthese de~ Mlnerzux Argileux a ~artir de gels.
Trans. 4th Intern. Congr, Soil_Scl., Amsterdam 3, 34-37;
Franzen, P., et al.
O Synthesis Or Nlckel Hydrosilicates Bull. Grp. ~ranc, Ar~iles 7, ~2] 21-30 (1956) Caillere, S., et al.
Etude de Quelques Silicates Nickéli~eres Naturels et de Synthese Contr. Mineral and Petrol. 34 84-86 (1972) Jasmund K., et al.
Synthesisor Mg^ and Ni-Antigorite Ibid,, 34 346 (1972) Jasmund, K,, et al.
Synthesis Or Mg- and Ni-Antigorite: A Correctlon Beitrage zur Mineralogie und Petrographie ~, 232-241 (1960) Noll, l~., et al.
Ueber synthetischen Kobaltchrysotil und seine Beziehun~en usw.
Bul. Soc. Franc. Miner. Crist. 79, 408-420 (1956) Caillere, S,, et al.
i Étude Exper~mentale du mécanisme de la rormation des antigorites nickelifères. , Kolloid-Zeitschrlft ~ 11 (1958) NO11J W., et al.
Adsorptionsvermoegen und spezi~ische Oberflaeche von Silikaten mit roehrenfoermig gebauten Primaerkristallen.
~ 7~3878 Typical o~ the patent llterature containlng procedure~
~or gynthesizing nickel serpentines and other so-called nickel serpentine minerals are the ~ollowlng:
u.s. 2,658,875 Schuit~ et al., November 10, 1953 53,686J341 Eberly August 22, 1972
3,686,348 Eberly August 22, 1972 3,692,700 Sa~yer et 31. September 19, 1972 3,729,429 Robson April 24, 1973 3,8~,741 Robson April 16) 1974 l3,838,041 Sawyer et ~1. September 24, 1974 ., .
8~7~3 `- The precursor nickel ~erpentlnes are made by a hydro-thermal proce~s; or they may be naturally occuring nlckel serpentlnes corresponding to the fore~oing descriptlon, to the extent that commercially workable deposlts thereof are avail-5 able to those desiring to practice the invention, as alreadydiscussed. In general we prefer to syn~hesize nickel serpen-tines ina~much as better control may then be had over the properties o~ the flnal product, with part-lcular rererence to such features as chemlcal composition, partlcle configuratlon, surface area~ and the like.
When the precursor nickel serpentines are to be obtained ; by synthesis, a procedure selected ~rom the extenslve prior art syntheses listed hereinabove may be used A general procedure which we prefer may be carrled out as ~ollows:
In general, relatively simple ~ources of the various elements present in the desired product and an alkali such as sodium hydroxide are added to water. The well-homogenized mixture i~ placed in a sealed pressure vessel, which is then brought to a preselected temperatureJ typically 250 C. to 350 C., and maintained there for a preselected period of time, typically one-hal~ or 60r even 72 hoursJ after whlch the ve~sel is cooled and the contents removedJ andJ i~ desired or necessary, washed ~ree of soluble salts and dried. Agitation durin~ the hydrothermal processing is generally desired ln large-scale preparations. The product i~ convenlently examined by x-ray dlffractlon as a check on any given run.
A general ~eed formula utilizing soluble salts is as ~ollows:
yNiC12 (6-y-x)MgC12 2xAlC13 (4-x)Sio2 (12-~ 4x ~ ~ ) NaOH nH2 0 where ~ is the mols of base in excess of that necessary to pre-cipitate all multivalent metals a~ thelr oxides or hydroxldes,and where n is approximately 200-350, preferably about 250.
_. . . . _ . . _ _ _ . . . ~
7~
The value~ o~ x ~nd y are the same a~ those set rorth ln the nickel ~e~ent:Lne ~ormula [1] given earller in this dlsclo~ure; we have ~ound that the 9ynthe~i~ed ~roduct~
exhlblt substantially the same ratlo of metal constltuents ; as ls present in the ~eed mixture, 90 that the values of x and y are the sa?ne for both reed and product; and are sub~ect to the same restralnt~ as already given in f`ormula [1~. For the NaOH there may be sub3tituted KOH, LiOH, NHl~OH, 1/2 Ca(OH)2, . or mlxture~ thereo~, or llke alkalizing agent.
O The foregolng feed formula shows the various metals added a~ their chloride salts. This i8 in generdl preferred, although other ~alts may be used, such a9 the cltrate, acetate, nitrate, and the like In general, ~ in formula [2] above may vary from zero to as hlgh a~ about 20, the higher values Or ~ being practical for weak bases such as NH40H. For strong bases a ~ value higher than 6 19 scarcely needed.
The constituents, save for the caustic a~d a mlnor portion o~ the added water, are conveniently placed in a suitable mixlng 'O device and homogenized, a~ter which the cau~tic is added in solutlon with contlnued mixing, For small-scale laboratory runs, a sllver-lined stalnless steel pressure vessel wlth a capacity of about 15 ml may be used, and heated ln an oven For batches of larger slze, autoclaves of sultable capaclty ~'5 may be used.
78~
\
The reed formula ~u~t glven does not recite ~luoride, whlch, Or course, i9 present whenever this optional component 19 desired to be present. When this 19 the case, we rind it best to add ~luoride as sodium ~luorlde to the ~eed mixture wlthout attempting j to reduce the ~mount of caustic to compensate. Indeed, quite in contrast to the metallic ions, not all o~ the ~luorlde ions present in the ~eed mlxture ultimately become part of the nickel '~
serpentine lattice, 90 that it is necessary to use a con-siderable excess Or sodium ~luoride. Up to six or eight mols () of ~odium ~luoride per formula weight ln the ~eed may for example ' be used, which wlll still result in somewhat less than one mol of rluorlde becoming part o~ the lattice; that iSJ slightly less than one hydroxyl will be isomorphousIy substltuted by fluoride. More sodium rluorlde may of course be use~, leading to a higher degree o~ substitution.
Consideration o~ the ~ormulas ror the feed and for the synthesized product will rnake it evident that soluble salts, ~or the most part sodium chloride, will appear as an admixture with the product when this type o~ reed mixture 19 used. In ~0 general it is desirable to separate out the soluble salts by thorough washing ~ith water. The washed product may then be drled, and lf deslredJ ground.
The silica may be ~dded ln any convenlent ~ormJ such as polysiliclc acid J which may be r~ade in accordance with United ~5 States Patent 3J649J556 to Hor~man. AlternativelyJ sodium silicate solution mdy be u~edJ taklng into account the caustic soda equivalent thereo~. The alumina 19 convenlently any ~inely-dlvlded reactlve rorm thereo~J such as alumlnum hydroxlde, some-time~ termed alumina trihydrate.
When the synthetic procedures set ~orth ln the prlor art articles and patents cited hereinabove are employed, due conslder-ation should Or course be given to the compositional restraints ~peci~ied in accord~nce wlth the inventlon.
7~387~
The nickel serpentine~ may also be readily ~yntheslzed by using a feed mlxture in whlch the various component~ are added in the form of their oxidesg basic oxid.e~ or carbonates, wlth-out added alk~li as such. This obviate~ the nece~lty for w~shing the product free of ~oluble salts. Examples showing this synthetic route wlll be given hereinbelow.
1' , .... . ...
` ` ~L071 3~
As we have explained hereinabove, ln order to ~orm our -inventive catalysts we calcine and reduce the selected niclcel serpentines so that their crystalllnlty iq destroyed,which may be termed "amorphous". One must, Or course, understand that this by no means implies that the structure is utterly ran~om. To the contrary, the relative dispositions o~ the component ions have been conditioned by their previous crystall:lne structure while in the precursor serpentlne state. However, in view Or the number Or di~erent atomic species present, it is quite beyond present-day technology to determine precisely what those dis-positlons are, so that the inventive catalysts can only be characterized in terms o~ their crystalline precursors and of the processing by way o~ calcination and reduction It will be understood that by "amorphous" we rerer to the essential non-appearance o~ the characteristic serpentine struc-ture in the x-ray di~rraction pattern, although diffuse metal oxide c~ystal patterns may appear, as ror example bunsenite, i.e. J nickel oxide, arter calcination,and crystallites of -~
metallic nickel arter reduction.
The temperature required ror calcination can Or course be readily determined by pilot tests; a temperature of about 700 ~.
to about 750 C. will be found adequateJ although the erfective range varles rrom abou~ 500 C. to about 900 C. The calcined product is then reduced by heating in a reducing, preferably hydrogen, atmosphere at an e~rective reducing temperature, which is ~ound to be ~rom about 500 C. to about 900 C. In both steps, the duration should be long enough to obtain the desired degree of reduction. Generally, three hours at 705 C. is adequate for calcination, and five or more hours at 650 C. ror reduction, the hydrogenJ pre~erably at a minimum Or one atmosphere. It will be appreciated that these temperatures and times are given by way of ~L~'78~
., xample and not by way o~ limltation, Simple preliminary tests well known to those in the x ray di~raction and catalytic arts wlll provide satls~actory processlng condi-tions ~or any given case, The calclnation and reduction can be conducted concurrently by heatlng the serpentine at a temperature above about 500 C. in the presence Or hydro-gen, In generalJ howeverJ the serpentine ls less easily re~
duced than the amorphous calcined serpentine and longer re-ductlon times are necessary when the serpentine is not cal-cined before reduction.
1~8~7~3 We now give some examples showing the practice Or our lnvention:
Example 1 Four mols Or polysilicic acldl made as described in U.S Patent 3~6l~9J556~ and six mols Or nickel carbonate (materials assaying 80.77~ NiC03 was used) were made into a slurry with water at 15~ total solids by weight with a high-speed mixer. The slurry was placed in an autoclave a~d maln-tained at 300 C. ~or rour hours, The apparatus was then cooled, and the nlckel serpentine recovered. It had the fol- :
i lowing ~ormula:
.
(Ni6 ~ (Si~ ) 10 (OH),8 Separate portions of the product were reslurried w~th ; :
various clay binders in the proportion o~ 80~ by weight o~
the nickel serpentine and 20% o~ the selected clay, using water and a laboratory mixer, and then dried, calcined at 705 C ror three hours, and ground to 30/60 mesh. One por-tion was also used without admixture, as the pure nickel ser-pentine. The samples thus prepared were given the rollowing designatlons:
Sam~le Clay Binder 1 A None 1 B kaolinite, from Georgia, U.S.A.
1 C saponlte, made as described in U.S. 3,855,147 ~a = OJ X ~ 1.43~ Y ~ O) 1 D sepiolite, rrom Nevada, U.S.A.
1 E hectorite, rrom Cali~ornia, U.S.A.
1 F attapulgite, ~rom Georgia, U.S.A.
1 G montmorillonite, from Wyoming3 U.S.A.
,:
~78~
The samples prepared as descrlbed above were then tested for their activity aa methanation catalysts. 8.4 cc Or each sample were placed in the reactor tube and reduced by heating in a hydrogen atmosphere for sixteen hours at 650 C., the hydrogen being passed through the sample (having a mesh size of passing 30 and retained on 60 U,S. Standard mesh) at a rate o~ 40 cc per minute. Subsequently, commencing at a temperature of about 200 C , a mixture o~ approximately 20 mol ~ carbon monoxide and 80 mol ~ hydrogen was passed through the catalyst '0 charge in the reactor, the latter being provided with sufricient instrumentation to determine temperatures, flow rates, and input and output gas compositions, and thus the percent conver-sion Or the carbon oxide to methane. The temperature was raised in steps at approximately thirty-minute intervals, to a maximum in general Or about 600 C. The input gas hourly space velocity (the volume Or gas per volume Or catalyst charge, per hour, at standard temperature and pressure) was 1500.
After the sequence of methanation tests Just described had been completed ror a given sample, the catalyst charge '0 was again reduced in hydrogen overnight at 650 C and then ror three hours at 850 C. A~ter cooling to 200 C., a second series Or methanation tests were commenced and carried out as berore, ending usually at about 600 C.
Results o~ the tests are given below in Table I, while '5 some typical gas composition data ror some Or the runs are l~
given ln Table II 1-7~387l~
Table 1 .
Sample Gm Ni ln Minimum Tem~erature~ de~ree C,~:
8.4 cc ror 100~ C0 conversion., ~or ~ 90~ C0 conv.
Charge Cataly~t reduced at Catalyst reduced 650 C. . at 850 C.
1 A 3.16 235 470 ,:
1 B 2.61 220 250 1 C 2~32 202 ~ 315 1 D 1.90 202 310 1~ E 2.7~ 243 45 ;
1 F 2.11 240 320 ,.
1 G 2.38 220 300 '. : ` . ' 37~87~
Table II
Sample ~C, of Exit ga~ composition~ mol percent Percent C0 No. run C0 H2 C~LI C2 converslon_ 1 A * 235 0.02 50.5 49.1 0.34 99.97 * 393 0 50.7 49.3 0 100 * 590 0.15 60.4 38.5 ~.o 99.6 ** 470 1.5 64.5 26.4 7.6 95.8 , ** 600 0.3 61.4 36.5 1.9 , 99.3 1 B * 220 0.06 55.21 42.232.49 99.9 * 235 0 55.1 1~4.70.21 100 * 500 0 57.7 42.3 0.02 100 * 600 0.31 53.9 44.1 1.7 99.3 ** 250 0 64.3 3005 5.2 100 ** 600 0 58.8 41.1 0.1 100 1 C * 202 0 60.8 37.~ 1.5 100 * 398 0 59.6 40.4 0 100 * 595 0 67.2 32.8 0.05 100 ** 315 o 57.4 39.6 3.0 100 , ** 585 0 59.3 40.2 0.52 100 1 D * 202 0 49.6 49.2 1.2 100 * 495 0 46.4 53.6 0.03 100 * 569 0.27 54.6 43.5 1.7 99 - 4 ** 310 0 60.8 33.1 6.1 100 ** 580 0 53,8 41~ ~ 7 1.6 100 -19- :
.. . . . . .
~7i 38~
.
Table II (continuedl Sample . C. o~ Exit gas composition, mol ~ Percent C0 No. run C0 H2 CH4 C02 conver~lon 1 E * 243 0.14 51.61,7.0 1.2 99-7 * 410 0 51.348.7 0 100 * 610 0 56.642.9 0.6 100 ** 405 0 50.548.3 1.2 100 ** 500 0 48.351.7 0 100 *~ 600 59~140.7 0,2 100 ) , ' 1 F * 230 0.9 52.843,3 3.0 98,2 * 2L~5 0 49.247.8 3. lO0 * 600 0 49.349,1 1.6 100 ** 320 59.834.3 5.9 100 ** S20 0 47.652.2 0.2 100 ** 610 0 52.546.6 1,0 100 * Runs on catalyst reduced at 650 C.
** Runs on catalyst reduced at 650 C, overnight and at 850 C.
~or three hours.
~ 7~37~3 :
Pne may see ~rom Table~ I and II that thls niclcel ser-pentlne is an excellent methanat~on catalyst, givlng substan-tially complete conversion o~ carbon monoxlde at a low tem-perature, vlz., 235 C Moreover, even a~ter being sub~ected j to the hlgh temperature Or 850 C. lt is stil~ a good catalyst giving nearly com~lete converslon at 470 C. Still ~urther, it operates well over the range up to about 600 C., whether lt was reduced at ~50 ~. or 850 C The criterion is whether the reaction between the hydrogen and the carbon monoxide has been catalyzed to give essentially equilibrium conversion o~
the starting materials, which is herein termed complete, or 100%, conversion. The thermodynamics Or the reaction are more ~avorable at lower temperatures. In addition, low oper-ating temperatures have obvious advantages ln equipment sim-pli~ication and longer expected life. However, the reactionshould not be conducted below about 200 C because o~ the formatlon of nickel carbonyl at lower temperatures.
Table II illustrates an important aspect o~ the lnventlon, in accordance with which the nickel serpentlne is lntlmately ~?0 admixed wlth up to about lts weight Or a water dispersible clay mineral, prererably by wet mixing and subsequent drying.
Suitable such clay mlnerals include montmorillonlte, bèidelllte, kaolinite, halloysite, saponlte, se~iollte, hectorite, atta-pulglte, lllite, and others. To be ~ure~ the clay, particularly when incorporated in the ~ashlon descrlbed, imparts strength and mechanical lntegrity to the catalyst particles, but it is surprising and entirely unex~ected that the clay addition causes the catalyst to give complete conversion at lower temperatures than otherwise, even when the clay-bearlng nickel serpentine catalyst i9 reduced at the hlgh temperature of 850 C. The latter ls of practlcal lmportance because momen--2l-- .... . . . , : . .
~L~78~37~
tary higll excursions Or temperature are well-nigh unavoidable in plant operation, and a good catalyst should remain undamaged when so treated.
Thus, considerlng Tables I and II, it may be seen that ; 20~ by weight o~ kaollnite lowers the 100~ conversion temper-ature rrom 235 C. to 220 C., and even more lmportantly lowers the complete converslon temperature a~ter the 850 C. treat-ment rrom 470 C. to 250 C. Similar beneficial e~ects may be observed for the other four clays used as binders in the runs Or 1 B through 1 F.
or course, more than one clay mineral may be used in a single preparation. For example, the nickel ser~entine prlor to calcination may be lntimately admixed with u~ to its own welght of a mixture of equal parts Or kaolinite and montmorillonite;
or a mixture of equal parts Or ~aponite and attapulgite, and so rorth, all ~re~erably by wet mixlng.
The tables are also exemplary Or the circumstance that the methanation resultlng rrom the hydrogenation should be carrled out at at least 200 C, (to avold nickel carbonyl for-mation) but in any case at a temperature high enough to e~fect substantial methanation Or the carbon oxide or carbon oxides involved, The latter temperature varle~ from one cal-cined and reduced nickel serpentine to anotherJ as is evldent ~rom the test results given hereinabove, and elsewhere herein.
-2?-8~
Example 2 The tests just as deacribed were carrled out on a ~urtherseries o~ mlxtures of the same nlckel serFentlne (designated as 2-A) wlth dirrerent proportion~ Or montmorillonite, in the form Or Wyoming bentonite rully converted to the sodium form and rreed Or dross by supercentrirugingJ ion exchanging, and spray drying. These catalysts were calcined at 705 C ror three hours, ground to 30/60 mesh, and reduced overnight, as berore, at 650 C.. After methanation testing, the catalysts were reduced at 650 C. overnight and at 900 C. for three hours berore additional methanation testing was undertaken. ~-The results rollow: :
Table III :
Methanation Activity: . ::
~ by weight Minimum C. ~or 90~ C0 Conversion Sample Montmorillonite * **
r:
2 A 0 . 225 ***
2 ~ 10 220 300 2 G ` 50 235 ***
* Catalyst reduced at 650 C. overnight ** Catalyst reduced at 650 C. overnight and then ~or three hours at 900 C.
*** Maximum conversion c 90% occured at 600 C
', -'3-788 ~1~
Table III shows that montmoril~onlte shares the pro~er-ties of the other c~ays listed ror sam~es lB through lF of reducing the erfectlve methanation tem~)erature, both when reduced at 650 C. and at 900 C. It will be recalled that sam~les lB through lF contained 20~ clay and 80% nickel ser-~entlne. The results shown in Table III ~or samples 2B through 2G exhibit the e~ect Or varying c~ay content over a wide range.
At 50~ montmorillonite (sample 2G) the activity o~ the catalyst reduced at 900 C. is ~oor, but the 235 C. ~igure ~o~ the cat-alyst reduced at 650 C. is remarkable, considering that this sam~le has only hal~ as much of the nickel ser~entine (before calcinlng) as sample 2A. It would a~pear that some synergistic action occurs between the clay and the nickel serpentlne to account for this extraordinary behavior, slnce clay minerals by themselves have substantially no methanatlon activity. ;
.
-2!l -37~3 Example 3 The synthesls descrlbed in Example 1 was carried out uslng, in additlon to the polysilicic acid and nickel carbon- -ate, magnesium oxlde and alumlna. The molar ratios of the several components were ln the same proportion as the nickel serpentine formed, viz.:
8~7~3 `- The precursor nickel ~erpentlnes are made by a hydro-thermal proce~s; or they may be naturally occuring nlckel serpentlnes corresponding to the fore~oing descriptlon, to the extent that commercially workable deposlts thereof are avail-5 able to those desiring to practice the invention, as alreadydiscussed. In general we prefer to syn~hesize nickel serpen-tines ina~much as better control may then be had over the properties o~ the flnal product, with part-lcular rererence to such features as chemlcal composition, partlcle configuratlon, surface area~ and the like.
When the precursor nickel serpentines are to be obtained ; by synthesis, a procedure selected ~rom the extenslve prior art syntheses listed hereinabove may be used A general procedure which we prefer may be carrled out as ~ollows:
In general, relatively simple ~ources of the various elements present in the desired product and an alkali such as sodium hydroxide are added to water. The well-homogenized mixture i~ placed in a sealed pressure vessel, which is then brought to a preselected temperatureJ typically 250 C. to 350 C., and maintained there for a preselected period of time, typically one-hal~ or 60r even 72 hoursJ after whlch the ve~sel is cooled and the contents removedJ andJ i~ desired or necessary, washed ~ree of soluble salts and dried. Agitation durin~ the hydrothermal processing is generally desired ln large-scale preparations. The product i~ convenlently examined by x-ray dlffractlon as a check on any given run.
A general ~eed formula utilizing soluble salts is as ~ollows:
yNiC12 (6-y-x)MgC12 2xAlC13 (4-x)Sio2 (12-~ 4x ~ ~ ) NaOH nH2 0 where ~ is the mols of base in excess of that necessary to pre-cipitate all multivalent metals a~ thelr oxides or hydroxldes,and where n is approximately 200-350, preferably about 250.
_. . . . _ . . _ _ _ . . . ~
7~
The value~ o~ x ~nd y are the same a~ those set rorth ln the nickel ~e~ent:Lne ~ormula [1] given earller in this dlsclo~ure; we have ~ound that the 9ynthe~i~ed ~roduct~
exhlblt substantially the same ratlo of metal constltuents ; as ls present in the ~eed mixture, 90 that the values of x and y are the sa?ne for both reed and product; and are sub~ect to the same restralnt~ as already given in f`ormula [1~. For the NaOH there may be sub3tituted KOH, LiOH, NHl~OH, 1/2 Ca(OH)2, . or mlxture~ thereo~, or llke alkalizing agent.
O The foregolng feed formula shows the various metals added a~ their chloride salts. This i8 in generdl preferred, although other ~alts may be used, such a9 the cltrate, acetate, nitrate, and the like In general, ~ in formula [2] above may vary from zero to as hlgh a~ about 20, the higher values Or ~ being practical for weak bases such as NH40H. For strong bases a ~ value higher than 6 19 scarcely needed.
The constituents, save for the caustic a~d a mlnor portion o~ the added water, are conveniently placed in a suitable mixlng 'O device and homogenized, a~ter which the cau~tic is added in solutlon with contlnued mixing, For small-scale laboratory runs, a sllver-lined stalnless steel pressure vessel wlth a capacity of about 15 ml may be used, and heated ln an oven For batches of larger slze, autoclaves of sultable capaclty ~'5 may be used.
78~
\
The reed formula ~u~t glven does not recite ~luoride, whlch, Or course, i9 present whenever this optional component 19 desired to be present. When this 19 the case, we rind it best to add ~luoride as sodium ~luorlde to the ~eed mixture wlthout attempting j to reduce the ~mount of caustic to compensate. Indeed, quite in contrast to the metallic ions, not all o~ the ~luorlde ions present in the ~eed mlxture ultimately become part of the nickel '~
serpentine lattice, 90 that it is necessary to use a con-siderable excess Or sodium ~luoride. Up to six or eight mols () of ~odium ~luoride per formula weight ln the ~eed may for example ' be used, which wlll still result in somewhat less than one mol of rluorlde becoming part o~ the lattice; that iSJ slightly less than one hydroxyl will be isomorphousIy substltuted by fluoride. More sodium rluorlde may of course be use~, leading to a higher degree o~ substitution.
Consideration o~ the ~ormulas ror the feed and for the synthesized product will rnake it evident that soluble salts, ~or the most part sodium chloride, will appear as an admixture with the product when this type o~ reed mixture 19 used. In ~0 general it is desirable to separate out the soluble salts by thorough washing ~ith water. The washed product may then be drled, and lf deslredJ ground.
The silica may be ~dded ln any convenlent ~ormJ such as polysiliclc acid J which may be r~ade in accordance with United ~5 States Patent 3J649J556 to Hor~man. AlternativelyJ sodium silicate solution mdy be u~edJ taklng into account the caustic soda equivalent thereo~. The alumina 19 convenlently any ~inely-dlvlded reactlve rorm thereo~J such as alumlnum hydroxlde, some-time~ termed alumina trihydrate.
When the synthetic procedures set ~orth ln the prlor art articles and patents cited hereinabove are employed, due conslder-ation should Or course be given to the compositional restraints ~peci~ied in accord~nce wlth the inventlon.
7~387~
The nickel serpentine~ may also be readily ~yntheslzed by using a feed mlxture in whlch the various component~ are added in the form of their oxidesg basic oxid.e~ or carbonates, wlth-out added alk~li as such. This obviate~ the nece~lty for w~shing the product free of ~oluble salts. Examples showing this synthetic route wlll be given hereinbelow.
1' , .... . ...
` ` ~L071 3~
As we have explained hereinabove, ln order to ~orm our -inventive catalysts we calcine and reduce the selected niclcel serpentines so that their crystalllnlty iq destroyed,which may be termed "amorphous". One must, Or course, understand that this by no means implies that the structure is utterly ran~om. To the contrary, the relative dispositions o~ the component ions have been conditioned by their previous crystall:lne structure while in the precursor serpentlne state. However, in view Or the number Or di~erent atomic species present, it is quite beyond present-day technology to determine precisely what those dis-positlons are, so that the inventive catalysts can only be characterized in terms o~ their crystalline precursors and of the processing by way o~ calcination and reduction It will be understood that by "amorphous" we rerer to the essential non-appearance o~ the characteristic serpentine struc-ture in the x-ray di~rraction pattern, although diffuse metal oxide c~ystal patterns may appear, as ror example bunsenite, i.e. J nickel oxide, arter calcination,and crystallites of -~
metallic nickel arter reduction.
The temperature required ror calcination can Or course be readily determined by pilot tests; a temperature of about 700 ~.
to about 750 C. will be found adequateJ although the erfective range varles rrom abou~ 500 C. to about 900 C. The calcined product is then reduced by heating in a reducing, preferably hydrogen, atmosphere at an e~rective reducing temperature, which is ~ound to be ~rom about 500 C. to about 900 C. In both steps, the duration should be long enough to obtain the desired degree of reduction. Generally, three hours at 705 C. is adequate for calcination, and five or more hours at 650 C. ror reduction, the hydrogenJ pre~erably at a minimum Or one atmosphere. It will be appreciated that these temperatures and times are given by way of ~L~'78~
., xample and not by way o~ limltation, Simple preliminary tests well known to those in the x ray di~raction and catalytic arts wlll provide satls~actory processlng condi-tions ~or any given case, The calclnation and reduction can be conducted concurrently by heatlng the serpentine at a temperature above about 500 C. in the presence Or hydro-gen, In generalJ howeverJ the serpentine ls less easily re~
duced than the amorphous calcined serpentine and longer re-ductlon times are necessary when the serpentine is not cal-cined before reduction.
1~8~7~3 We now give some examples showing the practice Or our lnvention:
Example 1 Four mols Or polysilicic acldl made as described in U.S Patent 3~6l~9J556~ and six mols Or nickel carbonate (materials assaying 80.77~ NiC03 was used) were made into a slurry with water at 15~ total solids by weight with a high-speed mixer. The slurry was placed in an autoclave a~d maln-tained at 300 C. ~or rour hours, The apparatus was then cooled, and the nlckel serpentine recovered. It had the fol- :
i lowing ~ormula:
.
(Ni6 ~ (Si~ ) 10 (OH),8 Separate portions of the product were reslurried w~th ; :
various clay binders in the proportion o~ 80~ by weight o~
the nickel serpentine and 20% o~ the selected clay, using water and a laboratory mixer, and then dried, calcined at 705 C ror three hours, and ground to 30/60 mesh. One por-tion was also used without admixture, as the pure nickel ser-pentine. The samples thus prepared were given the rollowing designatlons:
Sam~le Clay Binder 1 A None 1 B kaolinite, from Georgia, U.S.A.
1 C saponlte, made as described in U.S. 3,855,147 ~a = OJ X ~ 1.43~ Y ~ O) 1 D sepiolite, rrom Nevada, U.S.A.
1 E hectorite, rrom Cali~ornia, U.S.A.
1 F attapulgite, ~rom Georgia, U.S.A.
1 G montmorillonite, from Wyoming3 U.S.A.
,:
~78~
The samples prepared as descrlbed above were then tested for their activity aa methanation catalysts. 8.4 cc Or each sample were placed in the reactor tube and reduced by heating in a hydrogen atmosphere for sixteen hours at 650 C., the hydrogen being passed through the sample (having a mesh size of passing 30 and retained on 60 U,S. Standard mesh) at a rate o~ 40 cc per minute. Subsequently, commencing at a temperature of about 200 C , a mixture o~ approximately 20 mol ~ carbon monoxide and 80 mol ~ hydrogen was passed through the catalyst '0 charge in the reactor, the latter being provided with sufricient instrumentation to determine temperatures, flow rates, and input and output gas compositions, and thus the percent conver-sion Or the carbon oxide to methane. The temperature was raised in steps at approximately thirty-minute intervals, to a maximum in general Or about 600 C. The input gas hourly space velocity (the volume Or gas per volume Or catalyst charge, per hour, at standard temperature and pressure) was 1500.
After the sequence of methanation tests Just described had been completed ror a given sample, the catalyst charge '0 was again reduced in hydrogen overnight at 650 C and then ror three hours at 850 C. A~ter cooling to 200 C., a second series Or methanation tests were commenced and carried out as berore, ending usually at about 600 C.
Results o~ the tests are given below in Table I, while '5 some typical gas composition data ror some Or the runs are l~
given ln Table II 1-7~387l~
Table 1 .
Sample Gm Ni ln Minimum Tem~erature~ de~ree C,~:
8.4 cc ror 100~ C0 conversion., ~or ~ 90~ C0 conv.
Charge Cataly~t reduced at Catalyst reduced 650 C. . at 850 C.
1 A 3.16 235 470 ,:
1 B 2.61 220 250 1 C 2~32 202 ~ 315 1 D 1.90 202 310 1~ E 2.7~ 243 45 ;
1 F 2.11 240 320 ,.
1 G 2.38 220 300 '. : ` . ' 37~87~
Table II
Sample ~C, of Exit ga~ composition~ mol percent Percent C0 No. run C0 H2 C~LI C2 converslon_ 1 A * 235 0.02 50.5 49.1 0.34 99.97 * 393 0 50.7 49.3 0 100 * 590 0.15 60.4 38.5 ~.o 99.6 ** 470 1.5 64.5 26.4 7.6 95.8 , ** 600 0.3 61.4 36.5 1.9 , 99.3 1 B * 220 0.06 55.21 42.232.49 99.9 * 235 0 55.1 1~4.70.21 100 * 500 0 57.7 42.3 0.02 100 * 600 0.31 53.9 44.1 1.7 99.3 ** 250 0 64.3 3005 5.2 100 ** 600 0 58.8 41.1 0.1 100 1 C * 202 0 60.8 37.~ 1.5 100 * 398 0 59.6 40.4 0 100 * 595 0 67.2 32.8 0.05 100 ** 315 o 57.4 39.6 3.0 100 , ** 585 0 59.3 40.2 0.52 100 1 D * 202 0 49.6 49.2 1.2 100 * 495 0 46.4 53.6 0.03 100 * 569 0.27 54.6 43.5 1.7 99 - 4 ** 310 0 60.8 33.1 6.1 100 ** 580 0 53,8 41~ ~ 7 1.6 100 -19- :
.. . . . . .
~7i 38~
.
Table II (continuedl Sample . C. o~ Exit gas composition, mol ~ Percent C0 No. run C0 H2 CH4 C02 conver~lon 1 E * 243 0.14 51.61,7.0 1.2 99-7 * 410 0 51.348.7 0 100 * 610 0 56.642.9 0.6 100 ** 405 0 50.548.3 1.2 100 ** 500 0 48.351.7 0 100 *~ 600 59~140.7 0,2 100 ) , ' 1 F * 230 0.9 52.843,3 3.0 98,2 * 2L~5 0 49.247.8 3. lO0 * 600 0 49.349,1 1.6 100 ** 320 59.834.3 5.9 100 ** S20 0 47.652.2 0.2 100 ** 610 0 52.546.6 1,0 100 * Runs on catalyst reduced at 650 C.
** Runs on catalyst reduced at 650 C, overnight and at 850 C.
~or three hours.
~ 7~37~3 :
Pne may see ~rom Table~ I and II that thls niclcel ser-pentlne is an excellent methanat~on catalyst, givlng substan-tially complete conversion o~ carbon monoxlde at a low tem-perature, vlz., 235 C Moreover, even a~ter being sub~ected j to the hlgh temperature Or 850 C. lt is stil~ a good catalyst giving nearly com~lete converslon at 470 C. Still ~urther, it operates well over the range up to about 600 C., whether lt was reduced at ~50 ~. or 850 C The criterion is whether the reaction between the hydrogen and the carbon monoxide has been catalyzed to give essentially equilibrium conversion o~
the starting materials, which is herein termed complete, or 100%, conversion. The thermodynamics Or the reaction are more ~avorable at lower temperatures. In addition, low oper-ating temperatures have obvious advantages ln equipment sim-pli~ication and longer expected life. However, the reactionshould not be conducted below about 200 C because o~ the formatlon of nickel carbonyl at lower temperatures.
Table II illustrates an important aspect o~ the lnventlon, in accordance with which the nickel serpentlne is lntlmately ~?0 admixed wlth up to about lts weight Or a water dispersible clay mineral, prererably by wet mixing and subsequent drying.
Suitable such clay mlnerals include montmorillonlte, bèidelllte, kaolinite, halloysite, saponlte, se~iollte, hectorite, atta-pulglte, lllite, and others. To be ~ure~ the clay, particularly when incorporated in the ~ashlon descrlbed, imparts strength and mechanical lntegrity to the catalyst particles, but it is surprising and entirely unex~ected that the clay addition causes the catalyst to give complete conversion at lower temperatures than otherwise, even when the clay-bearlng nickel serpentine catalyst i9 reduced at the hlgh temperature of 850 C. The latter ls of practlcal lmportance because momen--2l-- .... . . . , : . .
~L~78~37~
tary higll excursions Or temperature are well-nigh unavoidable in plant operation, and a good catalyst should remain undamaged when so treated.
Thus, considerlng Tables I and II, it may be seen that ; 20~ by weight o~ kaollnite lowers the 100~ conversion temper-ature rrom 235 C. to 220 C., and even more lmportantly lowers the complete converslon temperature a~ter the 850 C. treat-ment rrom 470 C. to 250 C. Similar beneficial e~ects may be observed for the other four clays used as binders in the runs Or 1 B through 1 F.
or course, more than one clay mineral may be used in a single preparation. For example, the nickel ser~entine prlor to calcination may be lntimately admixed with u~ to its own welght of a mixture of equal parts Or kaolinite and montmorillonite;
or a mixture of equal parts Or ~aponite and attapulgite, and so rorth, all ~re~erably by wet mixlng.
The tables are also exemplary Or the circumstance that the methanation resultlng rrom the hydrogenation should be carrled out at at least 200 C, (to avold nickel carbonyl for-mation) but in any case at a temperature high enough to e~fect substantial methanation Or the carbon oxide or carbon oxides involved, The latter temperature varle~ from one cal-cined and reduced nickel serpentine to anotherJ as is evldent ~rom the test results given hereinabove, and elsewhere herein.
-2?-8~
Example 2 The tests just as deacribed were carrled out on a ~urtherseries o~ mlxtures of the same nlckel serFentlne (designated as 2-A) wlth dirrerent proportion~ Or montmorillonite, in the form Or Wyoming bentonite rully converted to the sodium form and rreed Or dross by supercentrirugingJ ion exchanging, and spray drying. These catalysts were calcined at 705 C ror three hours, ground to 30/60 mesh, and reduced overnight, as berore, at 650 C.. After methanation testing, the catalysts were reduced at 650 C. overnight and at 900 C. for three hours berore additional methanation testing was undertaken. ~-The results rollow: :
Table III :
Methanation Activity: . ::
~ by weight Minimum C. ~or 90~ C0 Conversion Sample Montmorillonite * **
r:
2 A 0 . 225 ***
2 ~ 10 220 300 2 G ` 50 235 ***
* Catalyst reduced at 650 C. overnight ** Catalyst reduced at 650 C. overnight and then ~or three hours at 900 C.
*** Maximum conversion c 90% occured at 600 C
', -'3-788 ~1~
Table III shows that montmoril~onlte shares the pro~er-ties of the other c~ays listed ror sam~es lB through lF of reducing the erfectlve methanation tem~)erature, both when reduced at 650 C. and at 900 C. It will be recalled that sam~les lB through lF contained 20~ clay and 80% nickel ser-~entlne. The results shown in Table III ~or samples 2B through 2G exhibit the e~ect Or varying c~ay content over a wide range.
At 50~ montmorillonite (sample 2G) the activity o~ the catalyst reduced at 900 C. is ~oor, but the 235 C. ~igure ~o~ the cat-alyst reduced at 650 C. is remarkable, considering that this sam~le has only hal~ as much of the nickel ser~entine (before calcinlng) as sample 2A. It would a~pear that some synergistic action occurs between the clay and the nickel serpentlne to account for this extraordinary behavior, slnce clay minerals by themselves have substantially no methanatlon activity. ;
.
-2!l -37~3 Example 3 The synthesls descrlbed in Example 1 was carried out uslng, in additlon to the polysilicic acid and nickel carbon- -ate, magnesium oxlde and alumlna. The molar ratios of the several components were ln the same proportion as the nickel serpentine formed, viz.:
4.425 gl.5Alg) (S13 925Alh) Olo(OH~8J
where g ~ h = 2x ~ 0.15.
Methanation tests and catalyst preparation as de-scrlbed ln Example 2 were carried out on the sample, with the rollowing results.
Table IV
' C. of Exit gas composi.tion, mol percent Percent C0 run C0 H2 CH4 C02 Conversion 220 * 0.1 57.9 39.0 3.0 99.7 ~::
300 * 0.0 50.8 48.8 0.4 100.
I~oo * 0.0 48 9 50.9 0.2 100.
500 * 0.0 50 6 48.7 o.8 100 .
600 * 1!0 56.6 39.~ 3.3 97.6 300 *~ 0.2 56.6 39.9 3.L~ 99-7 L~oo ** o~ o 55.0 42.3 2.6 100 500 ** 0.1 53.3 44.9 1 7 99 9 600 ** 1 2 57.3 37.8 3.7 97-3 * Runs on catalyst reduced at 650 C.
** Runs on catalyst reduced at 650 C. ove.rnight and r' then at 900 C. for three hours.
It will be seen t.hat thls nickel serpentine wa~ like-wise the precursor of an e~cellent methanation catalyst.
7887~
Example 4 A series of nicke~ serpentines were Frepared by hydrothermal synthesls rOr four hours at 300 C , with varying amounts of nlckel per unit cell. l'he general procedure was that o~ Example 1. Table V which rollows, gives the grams Or the starting materlals, all batches belng made up to 15% total solids. Also shown are the expected unit cell compositions o~ the products.
Table V
Sample S102 (1) NiC03 (2) MgO (3) Unit Cell Composltlon No grams grams grams 3A 1200 4060 100 (Ni5 5Mgo 5) Si4lO(OH)8 3B 82 l~ 236.9 14~4 (NisMg) Si401o(0H)g 3C 135.6 373.2 35.2 (N14 5Mgl 5) Si4lO(OH)8 3D 145.8 268.3 76.7 ~Ni3Mg3) Si~Olo(O )8 3E 158 4 145.6 124.5 (Nil 5Mg4 5) silllo(H)8 (1) As polysilicic acid (2) 80 77~ actlve (3) 96~ active Berore calcination and reduction, all samples ~ere admixed by wet mixing as before with montmorillonite as de-scribed in Example 1J in the proportion of 5~ clay and 95 nickel serpentine.
The methanation catalytic actlvity and catalyst pre-paration were as in Example 2, with the following result~:
-26~
78~371~
Table VI
Methanation Activity:
Minimum C. for ~ 90~ C0 Conversion r * **
Sample 3C 2l~0 250 F
3D 2l~0 2L~o ' * Catalyst reduced at 650 C overnight.
** Catalyst reduced at 650 C. overnight and at 900 C ~or three hours.
.. . .
As may be seen from Table VI, all samples performed well, although sample 3E su~rered somewhat ~rom relatively low nickel content. The optimum content Or nickel ~rom a practical standpoint of course varies with the price of nickel at the time in question, so that one must balance cost against effectiveness. In times of high nickel prices, sample 3E
would be considered satisractory, while during times of low-nickel prices, one would naturally choose a nickel serpentine more along the lines Or sample 3A, 3B, 3C, or 3D
7~
Example 5 So~e of the nickel serpentines described ln Example 4 were tested for methanation activity, arter formlng into catalysts by calcining at 705 C. for three hours and hydro-gen reduction at 650 C, overnightJ for the conversion of carbon dioxlde into methane. This reaction is more difficult to catalyze than that of carbon monoxide, as is generally recog- ;
nizedJ although it does not have the same commercial importance as the methanation o~ the latter.
The nickel serpentines were mixed with 5~ montmorillonite as already described, and the mesh slze and catalyst charge were likewise the same as in,the earlier examples. The reed gas was 15 mol % carbon dioxide and 85 mol ~ hydrogen.
Results are shown in Table VII as follows:
. .. .
- 2~) .f ~ 7~7~
, .
Table VII
Sample c,Or Exlt Gas Composition, Mol ,q6 _ Percent C02 L
No. run C0 ~l2 CH4 C2 Conver~lon 3 C 280 o 66.9 27.7 5.4 83.6 300 0 6?.1 35.3 2. 6 93.1 400 0 56.9 42.4 0.7 98.4 500 o.4 61.9 34.6 3.1 91.9 ;~
600 2.3 71.2 21.6 4.9 82.9 3 D 300 0 82.0 14. 8 3.2 82.2 325 0 80.3 19.2 0.5 97.6 400 o 81.1 18.9 0 100 .
500 0.1 77.6 22~0 0.3 98.6 600 0.5 79.7 16.8 2.0 90.1 3 E 320 0 77.6 16.0 6.1~ 71.4 340 0 76.3 20.1 3.6 8500 400 0 70.1 29.4 0.5 98.4 500 0.2 72.7 25.9 1.2 95.5 600 2.1 80.2 ~4.6 3.1 84.6 The excellent catalytic e~rectiveness for carbon dioxlde methanation may be seen rrom Table VII. Substantial catalytic ..
actlvlty set in at around 350 C.
.
-2'~-1~'7~
.
Example 6 A natural nickel ~erpentine rrom Riddle, Oregon, was tested as a precursor for a methanation catalyst for carbon monoxide. The analy~is Or the materlal drled at 110 C wa~ :
as rOllOws:
Table VIII
Constltuent Wei~ht Percent Fe203 (total) 3.59 . Mn23 0 04 Cr~203 O. 01 , Ti2 0 003 CaO 0.05 A123 o, 42 MgO 29.97 H20 12.63 Total:100.22 X-ray di~fraction analysls showed a typical nickel ~erpen-tine, with a spacing of approxlmately 7 A
. The mlneral, which had been ground to pas~ 200 mesh, was calcined in air at 705 C. ror three hoursJ and then placed in the reactor, where it was reduced with hydro~en ror rourteen hour~ at 650 C
7~38~
. :
Uslng a gas feed Or 20 mol percent carbon monoxide and 80 mol percent hydrogen, the ~ollowlng percent conver~ion~
were obtained:
Table IX
Reactor Temperature, C. Percent C0 Conversion _ _ "
These results are quite good, especlally considering the relatively low nlckel content o~ the sample, whlch was about 0.78 nickel atoms per unit cell, corresponding to .y = 0.67 ln Formula ~1].
~8~7~
, . :
The roregolng disclosure illustrates the manner of carrying out the invention, and shows many o~ the advantages thereof.
It will be evident to those slllled in the art that in many methanation installations on a commercial scale, the oxides Or carbon to be converted to methane will be prese~t in a mixture Or various components Thus, carbon monoxide and carbon dioxide may both be present; and depending upon the source Or the carbon oxides and Or the hydrogen, more or less other gases such as nitrogen, water vapor and the like may be present. These will in general ofrer no bar to the successful carrying out Or the invention.
In Equation [1], and in the dlscussion of the reed for- -mula whereby the precursor nickel serpentines used in the in-vention may be ~ormed, rluoride is shown as an optional com-ponent. In general this ~ay be omitted without appreciably altering the bahavior of the calcined catalyst. However it i8 sometimes an aid ln crystallization ~rom the starting ~eed mixture, and its optional inclusion has been set ~orth herein for that reason.
'0 ~ngstrom units (one-tenth nanometer) have been abbreviated "A" ln accordance with common usage, ln this speclfication.
10~7~ 7~3 . ~ ~
It will be understood that while we have explained the inventlon wlth the ald Or .specl~ic examples, nevertheless considerable varlation is possible in choice of raw materials, proportlons, processlng conditions, and the like, wlthin the broad scope Or the inventlon as set ~orth in the claims whlch rollow. Thus, ror example, our inventive catalyst may be used simultaneously with other catalytic materlals, so as to sult particular eonditions and circumstances. Further, the calcination and reducti.on may be carried out as separate or overlapping steps.
, :
: ....
where g ~ h = 2x ~ 0.15.
Methanation tests and catalyst preparation as de-scrlbed ln Example 2 were carried out on the sample, with the rollowing results.
Table IV
' C. of Exit gas composi.tion, mol percent Percent C0 run C0 H2 CH4 C02 Conversion 220 * 0.1 57.9 39.0 3.0 99.7 ~::
300 * 0.0 50.8 48.8 0.4 100.
I~oo * 0.0 48 9 50.9 0.2 100.
500 * 0.0 50 6 48.7 o.8 100 .
600 * 1!0 56.6 39.~ 3.3 97.6 300 *~ 0.2 56.6 39.9 3.L~ 99-7 L~oo ** o~ o 55.0 42.3 2.6 100 500 ** 0.1 53.3 44.9 1 7 99 9 600 ** 1 2 57.3 37.8 3.7 97-3 * Runs on catalyst reduced at 650 C.
** Runs on catalyst reduced at 650 C. ove.rnight and r' then at 900 C. for three hours.
It will be seen t.hat thls nickel serpentine wa~ like-wise the precursor of an e~cellent methanation catalyst.
7887~
Example 4 A series of nicke~ serpentines were Frepared by hydrothermal synthesls rOr four hours at 300 C , with varying amounts of nlckel per unit cell. l'he general procedure was that o~ Example 1. Table V which rollows, gives the grams Or the starting materlals, all batches belng made up to 15% total solids. Also shown are the expected unit cell compositions o~ the products.
Table V
Sample S102 (1) NiC03 (2) MgO (3) Unit Cell Composltlon No grams grams grams 3A 1200 4060 100 (Ni5 5Mgo 5) Si4lO(OH)8 3B 82 l~ 236.9 14~4 (NisMg) Si401o(0H)g 3C 135.6 373.2 35.2 (N14 5Mgl 5) Si4lO(OH)8 3D 145.8 268.3 76.7 ~Ni3Mg3) Si~Olo(O )8 3E 158 4 145.6 124.5 (Nil 5Mg4 5) silllo(H)8 (1) As polysilicic acid (2) 80 77~ actlve (3) 96~ active Berore calcination and reduction, all samples ~ere admixed by wet mixing as before with montmorillonite as de-scribed in Example 1J in the proportion of 5~ clay and 95 nickel serpentine.
The methanation catalytic actlvity and catalyst pre-paration were as in Example 2, with the following result~:
-26~
78~371~
Table VI
Methanation Activity:
Minimum C. for ~ 90~ C0 Conversion r * **
Sample 3C 2l~0 250 F
3D 2l~0 2L~o ' * Catalyst reduced at 650 C overnight.
** Catalyst reduced at 650 C. overnight and at 900 C ~or three hours.
.. . .
As may be seen from Table VI, all samples performed well, although sample 3E su~rered somewhat ~rom relatively low nickel content. The optimum content Or nickel ~rom a practical standpoint of course varies with the price of nickel at the time in question, so that one must balance cost against effectiveness. In times of high nickel prices, sample 3E
would be considered satisractory, while during times of low-nickel prices, one would naturally choose a nickel serpentine more along the lines Or sample 3A, 3B, 3C, or 3D
7~
Example 5 So~e of the nickel serpentines described ln Example 4 were tested for methanation activity, arter formlng into catalysts by calcining at 705 C. for three hours and hydro-gen reduction at 650 C, overnightJ for the conversion of carbon dioxlde into methane. This reaction is more difficult to catalyze than that of carbon monoxide, as is generally recog- ;
nizedJ although it does not have the same commercial importance as the methanation o~ the latter.
The nickel serpentines were mixed with 5~ montmorillonite as already described, and the mesh slze and catalyst charge were likewise the same as in,the earlier examples. The reed gas was 15 mol % carbon dioxide and 85 mol ~ hydrogen.
Results are shown in Table VII as follows:
. .. .
- 2~) .f ~ 7~7~
, .
Table VII
Sample c,Or Exlt Gas Composition, Mol ,q6 _ Percent C02 L
No. run C0 ~l2 CH4 C2 Conver~lon 3 C 280 o 66.9 27.7 5.4 83.6 300 0 6?.1 35.3 2. 6 93.1 400 0 56.9 42.4 0.7 98.4 500 o.4 61.9 34.6 3.1 91.9 ;~
600 2.3 71.2 21.6 4.9 82.9 3 D 300 0 82.0 14. 8 3.2 82.2 325 0 80.3 19.2 0.5 97.6 400 o 81.1 18.9 0 100 .
500 0.1 77.6 22~0 0.3 98.6 600 0.5 79.7 16.8 2.0 90.1 3 E 320 0 77.6 16.0 6.1~ 71.4 340 0 76.3 20.1 3.6 8500 400 0 70.1 29.4 0.5 98.4 500 0.2 72.7 25.9 1.2 95.5 600 2.1 80.2 ~4.6 3.1 84.6 The excellent catalytic e~rectiveness for carbon dioxlde methanation may be seen rrom Table VII. Substantial catalytic ..
actlvlty set in at around 350 C.
.
-2'~-1~'7~
.
Example 6 A natural nickel ~erpentine rrom Riddle, Oregon, was tested as a precursor for a methanation catalyst for carbon monoxide. The analy~is Or the materlal drled at 110 C wa~ :
as rOllOws:
Table VIII
Constltuent Wei~ht Percent Fe203 (total) 3.59 . Mn23 0 04 Cr~203 O. 01 , Ti2 0 003 CaO 0.05 A123 o, 42 MgO 29.97 H20 12.63 Total:100.22 X-ray di~fraction analysls showed a typical nickel ~erpen-tine, with a spacing of approxlmately 7 A
. The mlneral, which had been ground to pas~ 200 mesh, was calcined in air at 705 C. ror three hoursJ and then placed in the reactor, where it was reduced with hydro~en ror rourteen hour~ at 650 C
7~38~
. :
Uslng a gas feed Or 20 mol percent carbon monoxide and 80 mol percent hydrogen, the ~ollowlng percent conver~ion~
were obtained:
Table IX
Reactor Temperature, C. Percent C0 Conversion _ _ "
These results are quite good, especlally considering the relatively low nlckel content o~ the sample, whlch was about 0.78 nickel atoms per unit cell, corresponding to .y = 0.67 ln Formula ~1].
~8~7~
, . :
The roregolng disclosure illustrates the manner of carrying out the invention, and shows many o~ the advantages thereof.
It will be evident to those slllled in the art that in many methanation installations on a commercial scale, the oxides Or carbon to be converted to methane will be prese~t in a mixture Or various components Thus, carbon monoxide and carbon dioxide may both be present; and depending upon the source Or the carbon oxides and Or the hydrogen, more or less other gases such as nitrogen, water vapor and the like may be present. These will in general ofrer no bar to the successful carrying out Or the invention.
In Equation [1], and in the dlscussion of the reed for- -mula whereby the precursor nickel serpentines used in the in-vention may be ~ormed, rluoride is shown as an optional com-ponent. In general this ~ay be omitted without appreciably altering the bahavior of the calcined catalyst. However it i8 sometimes an aid ln crystallization ~rom the starting ~eed mixture, and its optional inclusion has been set ~orth herein for that reason.
'0 ~ngstrom units (one-tenth nanometer) have been abbreviated "A" ln accordance with common usage, ln this speclfication.
10~7~ 7~3 . ~ ~
It will be understood that while we have explained the inventlon wlth the ald Or .specl~ic examples, nevertheless considerable varlation is possible in choice of raw materials, proportlons, processlng conditions, and the like, wlthin the broad scope Or the inventlon as set ~orth in the claims whlch rollow. Thus, ror example, our inventive catalyst may be used simultaneously with other catalytic materlals, so as to sult particular eonditions and circumstances. Further, the calcination and reducti.on may be carried out as separate or overlapping steps.
, :
: ....
Claims (19)
1. In a process wherein a carbon oxide is catalytically hydrogenated so as to form methane by passing said carbon oxide together with hydrogen over a heated catalyst, the improvement which comprises utilizing as said catalyst an amorphous nickel silicate resulting from the calcination and reduction of a nickel serpentine having a chemical composition represented by the following:
(NiyRgM6-y-g) ? (RhSi4-h) O10 (OH,F)8; wherein M is Mg, Co++, Fe++, Cu++, Mn++, Zn++, or mixtures thereof;
R is Al, Cr+++, or mixtures thereof;
Zn ? 4, Cu ? 0.5, Mn ? 0.5, g + h = 2x O ? x < 0.1; 0.5 ? y ? 6; and wherein the first parenthesis shows the cations in the octahedral layer and the second parenthesis shows the cations in the tetrahedral layer; and wherein from zero to two fluoride ions may be present for a total of eight hydroxide plus fluoride; this precursor nickel serpentine prior to calcining being a 1:1 trioctahedral phyllo-silicate in general having a substantially balanced framework, from the standpoint of total charge, with no exchangeable ions needed for neutrality, said calcination and reduction being carried out at a temperature of about 500°C to about 900°C and for a time sufficient to destroy the crystallinity of the precursor nickel serpentine and produce said amorphous nickel silicate, and reduction being performed in the presence of hydrogen.
(NiyRgM6-y-g) ? (RhSi4-h) O10 (OH,F)8; wherein M is Mg, Co++, Fe++, Cu++, Mn++, Zn++, or mixtures thereof;
R is Al, Cr+++, or mixtures thereof;
Zn ? 4, Cu ? 0.5, Mn ? 0.5, g + h = 2x O ? x < 0.1; 0.5 ? y ? 6; and wherein the first parenthesis shows the cations in the octahedral layer and the second parenthesis shows the cations in the tetrahedral layer; and wherein from zero to two fluoride ions may be present for a total of eight hydroxide plus fluoride; this precursor nickel serpentine prior to calcining being a 1:1 trioctahedral phyllo-silicate in general having a substantially balanced framework, from the standpoint of total charge, with no exchangeable ions needed for neutrality, said calcination and reduction being carried out at a temperature of about 500°C to about 900°C and for a time sufficient to destroy the crystallinity of the precursor nickel serpentine and produce said amorphous nickel silicate, and reduction being performed in the presence of hydrogen.
2. A process in accordance with Claim 1 wherein M is Mg, and R is Al.
3. A process in accordance with Claim 1 wherein said carbon oxide is a mixture of carbon monoxide and carbon dioxide.
4. A process in accordance with Claim 2 wherein said carbon oxide is a mixture of carbon monoxide and carbon dioxide.
5. A process in accordance with Claim 1 wherein said y has a value of between 1 and about 4.
6. A process in accordance with Claim 2 wherein said y has a value of between 1 and about 4.
7. A process in accordance with Claim 1 wherein said catalyst during said hydrogenation is heated to a tem-perature of at least about 200°C. but to a temperature high enough to effect substantial methanation of said carbon oxide.
8. A process in accordance with Claim 2 wherein said catalyst during said hydrogenation is heated to a tem-perature of at least about 200°C. but to a temperature high enough to effect substantial methanation of said carbon oxide.
9. A process in accordance with Claim 1 wherein said nickel serpentine prior to said calcination is intimately admixed with up to about its own weight of clay mineral.
10. A process in accordance with Claim 9 in which said clay mineral is selected from the class consisting of montmorillonite, beidellite, kaolinite, halloysite, saponite, sepiolite, hectorite, attapulgite, illite, and mixtures thereof.
11. A process in accordance with Claim 9 in which said admixing is brought about by wet mixing.
12. A process in accordance with Claim 10 in which said admixing is brought about by wet mixing.
13. A process in accordance with Claim 10 in which said clay mineral is selected from the group consisting of kaolinite, montmorillonite and mixtures thereof.
14. A process in accordance with Claim 1 wherein M is Mg and x = 0.
15. A process in accordance with Claim 14 wherein 3.0 ? y ? 6Ø
16. A process in accordance with Claim 15 wherein said nickel serpentine is intimately admixed with up to about its own weight of a clay mineral.
17. A process in accordance with Claim 16 wherein said clay mineral is selected from the group consisting of kaolinite, montmorillonite, beidellite, halloysite, saponite, sepiolite, hectorite, attapulgite, illite, and mixtures thereof.
18. A process in accordance with Claim 16 wherein said clay mineral is selected from the group consisting of kaolinite, montmorillonite, and mixtures thereof.
19. A process in accordance with Claim 17 wherein y = 6.
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US59651875A | 1975-07-16 | 1975-07-16 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1078878A true CA1078878A (en) | 1980-06-03 |
Family
ID=24387625
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA250,363A Expired CA1078878A (en) | 1975-07-16 | 1976-04-15 | Process of catalytic methanation |
Country Status (4)
| Country | Link |
|---|---|
| JP (1) | JPS5211186A (en) |
| CA (1) | CA1078878A (en) |
| DE (1) | DE2631901A1 (en) |
| GB (1) | GB1564004A (en) |
Families Citing this family (12)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS5452958A (en) * | 1977-10-04 | 1979-04-25 | Matsushita Electric Ind Co Ltd | Elastic surface wave device |
| US4276528A (en) * | 1978-03-08 | 1981-06-30 | Omron Tateisi Electronics Co. | Electric motor-driven timer |
| DE2952683A1 (en) * | 1979-12-29 | 1981-07-02 | Ruhrchemie Ag, 4200 Oberhausen | METHANIZATION CATALYST AND METHOD FOR PRODUCING IT |
| US4441880A (en) * | 1981-04-23 | 1984-04-10 | Pownall Spencer Engineering, Ltd. | Drying apparatus |
| JPS60229414A (en) * | 1984-04-27 | 1985-11-14 | Hitachi Ltd | Elastic surface wave device |
| JPS60249411A (en) * | 1984-05-25 | 1985-12-10 | Hitachi Ltd | Surface acoustic wave device |
| JP2725697B2 (en) * | 1984-12-14 | 1998-03-11 | 株式会社 日立製作所 | Surface acoustic wave device |
| JP2535328B2 (en) * | 1986-02-28 | 1996-09-18 | スズキ株式会社 | Swing arm for rear two-wheel vehicle |
| GB2222963B (en) * | 1988-09-23 | 1992-01-02 | British Gas Plc | Catalysts |
| DD299623A5 (en) * | 1989-05-16 | 1992-04-30 | ��������@��@�@�����@�������@��@������������@�}����������@�k�� | NICKEL / SILICON CATALYST AND METHOD AND MANUFACTURE THEREOF |
| RU2014123057A (en) * | 2011-11-08 | 2015-12-20 | Басф Се | METHOD FOR PRODUCING METHANIZATION CATALYST AND METHOD FOR SYNTHESIS-GAS METHANIZATION |
| CN107376915B (en) * | 2017-08-25 | 2020-02-07 | 王婵 | Carbon dioxide methanation catalyst and preparation method thereof |
-
1976
- 1976-04-15 CA CA250,363A patent/CA1078878A/en not_active Expired
- 1976-07-14 GB GB29182/76A patent/GB1564004A/en not_active Expired
- 1976-07-15 DE DE19762631901 patent/DE2631901A1/en active Pending
- 1976-07-16 JP JP51084054A patent/JPS5211186A/en active Pending
Also Published As
| Publication number | Publication date |
|---|---|
| GB1564004A (en) | 1980-04-02 |
| JPS5211186A (en) | 1977-01-27 |
| DE2631901A1 (en) | 1977-02-03 |
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Legal Events
| Date | Code | Title | Description |
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| MKEX | Expiry |