Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
1117053
1 BACKGROUND _F ~IE I. ~NTION
2 This invention relates co an improved process or
3 converting coal or carbonaceous materials derived from coal.
4 More particularly, this invention relates to a process for
conver~ing coal or carbonaceous materials derived from coal
6 wherein cations exhibiting catalytic activity for the
7 particular conversion process involved are effectively dis-
8 tributed through the coal or carbonaceous material derived
9 from coal prior to subjecting the same to the particular
0 conversion process involved.
11 As is we'~]. known, coal has long been used as a fuel
12 in many areas. For several reasons such as handling problems,
13 waste disposal problems, pollution problems and the like, coal
14 has not been a particularly desirable fuel from the ultimate
consumers point of view. As a result, oil and gas have
16 en;oyed a dominant position, fron the standpoint of fuel
17 sources, throughout the world.
18 As is also w~ll known, proven petroleum and gas
19 reserves are shrinking throughout the world and the need
for alternate sources of energy is becoming more and more
21 apparent. One such alternate source is, of course, coal
22 since coal is an abundant fossil fuel, particularly in the
23 United States. Before coal will be widely accepted as a
24 fuel, however, it is believed necessary to convert the same
to a form which will not suffer from the several disadvan~
26 tages alluded to previously.
27 To this end, several processes ~lerein coal is
28 either liqueied and/or gasified have been proposed heretofore.
~ Many of the.se processes have employed a variety of catalytic
materials that have been more or less successful in promoting
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1 the desired conversion. In order ~or such materials to be
2 completely effective, however, it is important that the cata-
3 lytie material be uniformly distributed throughout the
4 coal structure. Due to the soli.d nature of coal, however,
the neeessary distribution has been difficult and as a result
6 many potential eatalytieally aetive materials eannot be
7 effeetively employed with eonventional techniques.
8 Recently, it has been taught in Catalytie Review -
9 Seience Engineering 14(1), 131-152 (1976) that this problem
ean be avoided with lower ranking coals by first ion-
11 exchanging a lower ranking coal with an alkali or an alkaline
12 earth metal cation and, particularly, sodium or calciurn. As
13 indieated in the artiele, this teehnique was not partieularly
14 effeetive in higher ranking eoals and the effect was not
signifieant in bituminous coal chars. The problem still
16 exists, then, with the higher ranking coals and, indeed,
17 the method proposed in the aforementioned article is not,
18 apparently, the ultimate solution even with respect to lower
19 ranking coals. The need, then, continues for a method of
distributing eatalytieally aetive materials in a higher
21 ranking coal whieh is destined for ultimate conversion,
22 particularly via-liqu~faetion arld/o~ gasifieation techniques.
23 Moreover, the need exists for still further improvement with
24 respect to eatalyst distribution even within the lower rank-
ing coals and particularly those which do not have suffieient
26 aeid sites to permit effective ion exchange.
27 SUMMA~Y OF THE INVENTION
28 It has now, surprisingly, been diseovered that the
29 foregoing and other disadvantages of the prior art eatalyst
distribution rnethods ean be overeome with the rnethod of the
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present invention and a method for effectively distributing
catalytic materials in higher ranking coals and an improved
method of distributing catalytic materials in lower ranking
coals provided thereby. It is, therefore, an object of this
invention to provide a method for distributing catalytic mater-
ials throughout coal and carhonaceous materials derived from
coal. It is another object of this invention to provide such
a process which is particularly effective in the distribution of
catalytic materials throughout higher ranking coals and such a
process which can be used to improve distribution throughout
lower ranking coals. It is still a further object of this in-
vention to provide such a process which can be used in combin-
ation with gasification and other coal conversion processes.
These and other objects and advantages will become apparent from
the description set forth hereinafter.
In accordance with this invention, the foregoing and
other objects and advantages are accomplished by subjecting the
coal to partial oxidation and then subjecting the oxidized coal
to ion exchange with a suitable metal cation. As indicated more
fully hereinafter, it is important that the oxidation be care-
fully controlled so as to prevent unnecessary loss of the coal
durin~ this pretreatment step. As is also more fully indicated
hereinafter, the particular cation used during the ion exchange
step will depend upon the particular catalytic activity desired
in the subsequent conversion. After the partial oxidation and
ion exchange has been completed, the thus treated coal will be
more easily converted in a gasification or similar conversion
process.
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DETA I LE~ DE S CR I PT I ON OF TIIE I NV13NT I ON
. _ _ . . ~ . .. . . _ _ _
2 ~s indicated supra, the present invention relates to
3 a method of distributing catalytically active materials
4 throughout a coal or a carbonaceous material derived from
coal, The distribution is accomplished by treating the coal
6 or the carbonaceous material derived from coal so as to
7 impart sites therein which can then be reacted with the
8 catalytic material. After this treatment, or simultane- ¦
ously therewith, these sites are then converted to the
desired catalytic site. The thus treated coal or carbon-
aceous material derived from coal will then be subjected
12 to a conversion operation such as gasification__liquofaotion
or the like.
14 In general, the distribution method of the present
S invention can be used with any coal including anthracite,
bituminous, subbituminous, lignite, peat, brown coal, and
the like. As previously indicated, however, the lowest ~-
ranking coals will generally have sufficient exchangeable
sites to permit effective distribution of the catalytic
material without prior treatment, The method of the present
invention is, then, most effective with the higher ranking
coals, which do not have sufficient sites to permit distri-
2 bution without pretreatment and the method of this invention
is particularly effective with the bituminous and subbitumi-
nous coals.
26 In general, the coal will be ground to a finely
divided state, The particular particle size, or particle
28 size range, actually employed will depend a great deal uponthe optimum size to be used in the subsequent conversion
process, although the actual particle size range employed
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1 will have some effect on the rate of pretreatment and the
2 rate of catalyst distribution. In this regard, it should
3 be noted that the coal would, generally, when treated in
4 accordance with this invention, be ground to a particle size
of less than about l/4-inch and preferably to a particle size
6 of less than about 8 mesh NBS sieve size. With respect to
7 particle size, it should be noted that the smaller sizes
8 will enhance both the pretreatment reaction rate snd at the
same time will enhance catalyst distribution. For these
reasons, then, the actual particle size employed will be
11 as small as is practically consistent with the requirements
12 for further processirlg and utilizing the coal.
13 In general, the active sites imparted on the coal
1 as a result of the pretreatment could be essentially any g
type of chemical site which would permit s1lbsequent or
16 simultaneous reaction with a desired catalytic compound.
Acidic sites are, however, most convenient to impart into
18 the coal and, therefore, will generally be the site o~
choice.
2 It will be appreciated that these sites could be
2 provided via any suitable technique and in accordance with
the theories set forth hereinafter. When acidic sites
are used, however, these can be provided via essentially
any known oxidizing technique. For example, the acidic
sites can be provided by oxidizing the finely divided coal
26 either with oxygen or an oxygen-containing gas such as air
27 or a flu gas, or the same may be provided through the use
28 of an oxidizing agent such as an acid, a peroxide, various
29 salts such as a perman~anate, a hypochlorite,'or the like.
~hen an acid is used essentially any acid, such as nitric
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1 acid and sulfur:Lc ac:~d, known ~o be useful as an oxidizing
2 agent càn be used. When a peroxide is used essentially
3 any peroxide including hydrogen peroxide, the various
4 organic peroxides, the various metal peroxides and the like
would be effective, When a salt such as a permanganate or
6 hypochlorite is used essentially any such salt would be
7 effective but it will be most convenient to use a salt
8 containing a cation identical to that to be used in the
9 subsequent catalyst distribution.
In general, any cation could be distributed
11 throughout the coal or a carbonaceous material derived
12 from coal after the pretreatment of this invention and,
3 surprisingly, any cation will impart some degree of cata-
4 lytic activity in subsequent conversion processes. Cations
15 that can be used in accordance with this invention, then, L
16 include those cations which are known to act as catalysts
17 in the various coal conversion processes. Surprisingly,
18 however, and in accordance with the present invention,
19 cations known to exhibit slight or limited catalytic
properties, by virtue of being physically intermixed with
21 the coal structure, have been found to exhlbit greatly
22 improved catalytic properties when chemically combined.
23 Cations which will exhibit catalytic activity when
24 incorporated into the coal in accordance with the present
invention include the alkali metals and the alkaline earth
26 metals of Groups I-A and II-A of the Periodic Chart of the
27 Elements (as reprinted in the Chemical Engineers Handbook,
28 th Edition, Percy ~ Shulton, published by McGraw-Hill Book
29 Company, New York, 1973). Effe,ctive cations also include
the metals o~ Groups I-B and II-B and the metals of Groups
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IV-~, IV-B, VI-B, VII-B and Group VIII. Of these, the alkali
and alkaline earth metals are particularly effective when the
coal is ultimately converted via a gasification reaction.
While the inventors do not wish to be bouhd by any
particular theory, it is believed that when oxidization is used
to impart the desired active sites, the reactions and subsequent
ion exchange proceeds throughout the significant internal pore
surface area of the coal, which is commonly of a magnitude of
several hundred square meters per gram of coal. It is also
believed that peroxides are first formed and the peroxides thus
formed decompose to yield acids. The acidic hydrogens can then
be ion-exchanged in accordance with the present invention.
With respect to the foregoing, and while the inven-
tors still do not wish to be bound by any particular theory,
it is believed that coal contains a plurality of aromatic
rings which are highly substituted; e.g., fused to other
aromatics or hydroaromatics or attached to alkyl, ether,
hydroxyl or the like, groups. Additionally, it is believed
that coal exhibits secondary structural characteristics
such as hydrogen bonding, interatomic ring bonds and the like,
which generate the three-dimensional structure of coal. As a
result, oxidation of coal can result in a broad range of free-
radical or acid sites. The formation of one such site, which
would be possible from a condensed structure containing three
aromatic rings, can be illustrated by the following equations:
;
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1 ~ + 2 -
2 ~.
3 ~ - b
4 As will be readily apparent, the free-radical sites illus-
5 trated in the second formula would readily react with
6 essentially any cation. As will also be readily apparent, f
7 especially in light of the complex coal structure and signif-
8 icant pore surface area, an unlimited number of such sites
9 are possible. Moreover, and with respect to the lower-
10 ranking coals which contain significant oxygen concentrations,
11 active sites different from those already contained in such
12 coals can be imparted through controlled oxidation. The
.
13 method of the present invention is, therefore, effective in
14 the treatment of such coals and especially such which do not
15 contain su~ficient exchangeable active sites,
16 In general, any amount of oxidation will provide
17 an increased number of reactive sites, especially in the
18 higher ranking coals and, therefore, will be beneficial
19 in the method of the present invention and will, generally,
20 increase the catalytic activity of any cation or cations
21 subsequently exchanged on to these sites. Best results
22 will, however, be obtained only after a suf~icient number
23 of active sites have been imparted into the coal to permit
24 the inclusion of from about l to about is Wt% of calcium or
25 equivalent amounts of another desired cation or cations.
26 In this regard, it should be noted that when monovalent
27 cations or cations heavier than calcium are used the equi-
28 valent amount ion exchanged will represent a greater
29 percentage by weight of the coal while with lighter or
30 trivalent cations the weight percentage could be less. The
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1 key, then, is really the number of catalytic sites per unit
2 weight of coal and sufficient catalytic activity will be
3 imparted when the coal contains between about 5 x 10 4 and
4 8 x 10-3 gram atomic equivalents of catalytic-active cation
per gram of coal.
6 With respect to the amount of catalytic-active
7 material being incorporated into the coal, it should be
8 noted that in those cases where the objective is to convert
9 the coal to either a-liquid-or- gaseous fuel, the prior oxi-
0 dation, to the extent that it converts a portion of the coal
11 to water and carbon oxides, will reduce the overall effi-
12 ciency of the conversion process by reducing the quantity of
13 coal available for subsequent conversion. The treatment
14 does, on the other hand, improve the ef~iciency of the overall
process by increasing catalytic activity and thereby reducing
16 the holding time and/or temperature required in the subsequent
17 conversion operation, The overall efficiency of the
18 improved process or processes of this invention is, then,
9 a balance resu~ting from these considerations. In this
regard, however, it should be noted that the advantages
21 resulting from ei'fective distribution of the catalyst far
22 outweigh the disadvantage resulting ~rom premature conver-
23 sion of the coal to C02 and H20 so a s to affect catalyst
24 distribution. Notwithstanding this, however, careshould
be exercised so as to avoid unnecessary oxidation of the
26 coal during the pretreatment step,
27 In general, any method known in the prior art
28 to be effective in controlling the rate and extent of
29 oxidation in a hydrocarbon can be used to affect the
desired oxidation of the coal in the method of this in-
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1 vention. 5uch methods include, but are not necessarily
2 limited to, control of oxidizing reagent concentration and
3 the temperature o~ oxidation. Control oI oxidizin~ reagent
4 concentration can, of course, be controlled by mixing the
reagent with a sui.table diluent during contacting. This
6 method would, of course, be most effective when a liquid
7 or solid oxidizing agent is employed but could be used even
8 when a gaseous-reducing agent is employed, In any case,
9 and even when oxidizing-agent concentration is controlled
during contacting it will, generally, be necessary to control
11 temperature primarily to insure that oxidation does occur
12 within a reasonable period of time. Effective oxidizing-
13 agent concentrations and effective oxidizing temperatures
14 are, of course, well within the ordinary skill o~ the art
and need not be set forth in detail herein.
,16 ~otwithstanding that effective concentrations and
17 temperatures are within the ordinary skill of the art, it
18 should be noted that when a gas, such as air, is employed
19 as the oxidizing agent, essentially any temperature and
pressure can be used during the oxidation and the exteIlt
21 of oxidation can be controlled by controlling the amount
22 of air actually contacting the coal and the temperature
23 at which contacting i9 accomplished. In th~s regard it
24 should be noted that sufficient oxidation of dry coal will
occur autogeneously at room temperature but at least five
26 to seven days exposure are generally required. As a
27 result, elevated temperatures are most effective but
28 temperatures approaching combustion temperature should
29 be avoided. Temperatures within the range from about 18C
,to about 425C are, then, considered effective. Tempera-
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1 tures within ~he range from about 175C.~o about 300C. are,
2 however, preferred since temperatures helow about 175C. do
3 not provide suf~icient re~ction rates while temperatures
4 above 300C. result in reaction rates approaching those
S of combustion. Due to the well-known time-temperature
6 effect, reaction times can vary from a few minu~es at the
7 higher temperatures to se~eral hours at the lower temper-
8 atures.
9 In general, any of the ion exchange techniques
known to be effective ~or exchanging any cation ~or a
11 hydrogen ion or a different cation can be used to effect
12 the desired catalyst distribution in the method of the
13 present inven~ion. These techniques include direct
14 contacting with a metal hydroxide in aqueous solution
where the metal correspond~s to the desired catalytic cation
16 and the various techniques wherein a me~al salt ls used to
17 efect the desired ion exchange. Again, when metal salts
18 are used the metal portion of the salt will correspond to
19 the cation sought to be imparted into the coal. In general,
aqueous solutions of a hydroxide or a salt of a weak acid
21 will be employed to effect the ion exchange. As is well
22 known, the ion exchange will occur at a basic pH; i.e.,
23 a pH ~reater than 7. The coal may, o~ course, be pre-
24 treated; i.e., prior to the ion exchange, with an organic
or inorganic acid such as formic acid or the like, to
26 remove undeslrable, naturally occurring, complexed elements.
27 When this is done, care should be exercised to insure that
28 the acid employed will not impart an undesirable anion into
29 the coal. Also, it will, gener~lly, be necessary to wash
out or neutralize the acidity of the aqueous medium prior
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to ion exchanqe. Such neutralization can, of course, be
accomplishecl in accordance with known techniques and need
not be discussed in detail herein. Notwithstanding this,
however, it should be noted that ammonia can be effectively
used to control the pH and that ammonia is particularly
effective when an acid pretreat is used and when alkali and
alkaline salts, particularly the halide salts, are used to
effect the desired ion exchange. The anion can then later
be removed by water washing or the like.
In the method heretofore desc~ibed, the pretreatment
or oxidation is accomplished prior to the ion exchange. It
is, however, within the scope of this invention to effect
both oxidation and ion exchange simultaneously. When this
is done, oxygen will either be bubbled through the ion
exchange solution during contacting with the coal, or
another suitable oxidizing agent will be incorporated into
the ion exchange solution. As in the previously described
embodiment, the simultaneous oxidation-ion exchange will be
accomplished in accordance with techniques known in the
prior art.
As indicated previously, the particular cation or
cations incorporated into the coal will depend upon the
subsequent conversion process employed. For example, and
as indicated previously, where the subsequent conversion is to
be via gasification, alkali and alkaline earth metals will
preferably be employed.
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1 In general, any o~ the gasification processes
2 known in the prior art can be improved with respect to
3 ei.ther yield, conversion rate of both when the catalyst
4 distribution method of this invention is employed prior
to effecting the gasification reaction. In general, these
6 gasification processes comprise a step wherein coal is
7 .reacted with a gaseous species or a mixture of gaseous
8 species at an elevated temperature, and, generally, an
9 elevated pressure to produce other, more desirable
gases. The gaseous species generally employed as react-
11 ants include oxygen, steam, carbon oxides such as carbon
12 dioxide, and hydrogen. Generally, temperature, pressure,
13 and flow rate in these processes as well as the mole ratio 1i
14 or relative ratio of reacting gases to coal will depend on
the specific process employed and the actual products desired
16 therefrom. In this regard, it should be noted that the
17 composition of the gaseous products from these processes
18 cal also be altered by the particular catalyst employed.
19 For example, and as is known in the prior art, the products
resulting from the gasification of coal with steam can be
21 enriched in methane through the use of an alkali metal that
22 promotes the conversion of carbon monoxide and hydro~en
23 to methane.
24 As previously indicated, the method of this
invention ~or distributing catalysts uniformly throughout
26 finely divided coal o~fers several advantages even when the
27 thus treated coal is to be consumed in a combustion process.
28 First, when an oxidation catalyst such as the noble metals
29 of Group VIII is used, the combustion will proceed more
rapidly to completion and, indeed, complete combustion would
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be effected at a lower temperature. Second, when the cation
imparted via the method of this invention reacts with sulfur
dioxide and/or sulfur trioxide at the conditions of combustion
a significant portion of the sulfur contained in the coal will
be removed, in the form of metal sulfates, sulfites and sulfides,
generally remaining in the ash. The net results, then, would be
to reduce nitrogen oxide and particulate emission to the
atmosphere as a result of lower temperature or more complete
combusti~on and to reduce sulfur oxide and sulfur trioxide
emissions to the atmosphere as a result of the reaction with a
cation.
A still further advantage of the present invention
is realized in gasification processes wherein the coal is
rapidly heated in a gaseous medium or in a vacuum and wherein the
coal particles have been previously treated such that a cation
is uniformly distributed therethrough. In this regard, it
should be noted that untreated coals of bituminous ran]c
generally soften and swell to a plastic consistency when heated
in this manner and often adhere to each other or to the walls
of the reactor system. This sticking or adhering tendency is,
however, significantly reduced or eliminated when the coal
has been pretreated so as to contain a uniformly distributed
cation by the method of this invention. This advantage is
particularly pronounced when the cation incorporated into the
coal is selected from the alkali and alkaline earth metals.
. .
DESCRIPTION OF THE PREFERRED EMBODIMENT
In a preferred embodiment of the present invention,
a higher ranking coal; i.e., a coal containing less oxygen
in an active form than would be required to impart from about
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2 to about 10 Wt~ calcium ion, will be oxidized with air such
that the resulting oxidized coal will contain between about
10 and 20 Wt~ oxygen and suffic~ent active sites to impart
between about 1 x 10 3 and 5 X 10 3 gram atoms equivalents
of a metallic cation per gram of coal, the thus oxidized
coal will be ion exchanged with an alkali or alkaline earth
metal cation and then subjected to gasification. In the
preferred embodiment, the air oxidation of the coal will be
accomplished in a fluid bed at a temperature within the range
from about 175 to about 300C and with an air flow rate
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1 within the range from about 20 to about 10,000 V/V/Hr.
2 The ion exchange will be accomplished either with the
3 hydroxide of the desired alkali or alkaline earth metal
4 or a suitable salt thereof. Alternately, the ion exchange
could be accomplished by first contacting the oxidized coal
6 with sodium hydroxide or other suitable sodium salt and
7 thereafter completely exchanging the sodium ion imparted into
8 the coal with the desired alkali or alkaline earth metal ion.
9 The second ion exchange will also be accomplished either with
the hydroxide of the desired alkali or alkaline earth metal
11 or a suitable salt thereof. Generally, both ion exchanges
12 will be accomplished at a temperature within the range from
3 about 18C to about 110C and at a pH within the range from
4 about 7 to about 14. In those cases where sodium or potassium
is the desired cation to be distributed throughout the coal
16 the hydro~ide could be used and the second exchange will,
7 of course, not be necessary. Sodium or potassium will be most
18 preferred when maximum methane production from gasification by
19 steam is desired. Calcium, on the other hand, will be most
preferred when production of carbon monoxide and hydrogen by
21 steam gasification is desired.
22 Gasification of the thus treated coal will be
23 accomplished by contacting the coal with steam at a temper-
24 ature within the range from about 400C to about 1000 C at
a steam flow-rate within the range from about 0.2 to about
26 5Q W/W/Hr. In general, essentially any pressure could be
27 used during this contacting, but pressures within the range
28 from about 0 to about 1000 psig are mos+ preferred.
29 Having thus broadly described the present invention
~ and set forth a preferred embodiment thereof, it is believed
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I that the same will become ~ven more ~pparent by re~erence to
2 the following examples. These examples are, however,
3 intended solely for the purpose of illustration and should
4 not be construed so as to limit the invention,
5 EXhMPLE 1
6 In this example, two 15-gram samples of a bituminous
7 rank coal from Illinois were oxidized with air and then ion-
8 exchanged with sodium hydroxide so as to distribute sodium
9 cation uniformly through the coal, Prior to oxidation, the
10 coal was ground to a particle size range ranging from about
11 0.15 mm to about 0.59 mm. Both oxidations were accomplished
12 at a temperature of about 200-230C and the holding time
3 was varied to produce a product having different oxygen
14 contents. The coal was maintained in a fluidized state
15 during oxidation. Before oxidation, the coal contained
16 14 Wt% oxygen. After oxidation, the first sample contained
17 about 17.5 Wt% oxygen and the second sample contained about
18 18.0 Wt% oxygen. Following oxidation, the oxidized coal
lg samples were placed in an aqueous solution of sodium hydroxide
20 and allowed to remain in this solution for several days. The
21 ion exchange was accomplished at room temperature (Ca 18C).
22 The samples were then washed with pure water for several days
23 so as to ensure complete removal of any sodium cations not
24 actually exchanged with the coal. The i.on exchanged coal
2S samples were then analyzed to determine cation content. The
26 results obtained are summarized in the following table which
27 also includes the results obtained with an unoxidized coal
28 identical to that used in this sample,
13
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Increased Oxygen Sodium Cation
2 Content, Wt~o Wt%
0 1.9
3.5 5.8
4 4.0 6.3
As will be readily apparent from the foregoing, the maximum
6 amount of sodium cation which can be incorporated into the
7 coal at the ion exchange conditions employed, increased with
8 increasing oxygen content.
9 EXAMPLE 2
In this example, the procedure of Example l.was
11 repeated except that ion exchange was accomplished with
12 potassium hydroxide rather than sodium hydroxide. Also,
3 five samples of coal identical to that used in Example 1
14 were oxidized to different oxygen levels instead of just
two. The final oxygen content and the amount of potassium
16 ion incorporated into the coal are summarized in the table
17 set forth below. For purposes of comparison, the amount of
18 potassium incorporated via the same ion exchange techniques
19 into an unoxidized coal is also included in the table.
20Increased OxygenPotassium Cation
Content, Wt% Wt%
O 4.0
22 1.3 5.5
3.5 6.2
23 3.8 7.2
4.8 8.9
24 7.4 11.2
From the foregoing, it will again be apparent that the
26 maximum amount of potassium incorporated into the coal
27 at the ion exchange conditions employed increased signifi-
28 cantly with increased oxygen content.
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1 EXAMPLE 3
2 In this example, the procedure of Example l was
3 repeated except that ion exchange was accomplished with
4 calcium hydroxide rather than sodium hydroxide. Also,
S eight samples o~ coal identical to that used in Example l
6 were oxidized to different oxygen levels instead of just
7 two, The final oxygen content and the amount of calcium
8 ion incorporated into the coal are summariæed in the table
9 set forth below. For purposes of comparison, the amount of
calcium incorporated via the same ion exchange techniques
11 into an unoxidized coal is also included in the table.
12Increased Oxygen Calcium Cation
Content ~t% Wt%
13 0 l.O
14 l 83 l 5
2 7 4 0
16 3 8 3 l
5 4 4 7
As again will be apparent from the foregoing the maximum
amount of calcium incorporated into the coal generally in-
creased as the oxygen content increased. The variations
indicated as oxygen content increased are, of course, within
22 experimental error.
EXA~PLE 4
24 In this example, a series of coking-gasi~ication
tests were completed with ion exchange coals prepared in
accordance with techniques described in Examples 1-3. For
2 purposes of comparison, identical runs were also made with
28 coal samples identical to those used in Examples 1-3, which
2~ contain sodium carbonate or potassium càrbonate in physical
admixture therewith rather than by ion exchange. In all
1~17~53
1 runs, the coking-gasification was accomplished with steam
2 at a flow rate of about 50 W/W/Hr at a te~.perature of 760C
3 and at atmospheric pressure. The results obtained at
4 different cation concentrations are summarized in a table
set forth below. For convenience, the results are compared
6 on the basis of the reaction rate at 50% conversion and the
7 rate is expressed as percent initial carbon converted per hour.
8 For reference purposes, the method by which the ion was
9 ineorporated into the coal is also set forth in the table
Atoms Cation/
Atoms Carbon ~ethod ofGasifieation
11 CationIn Coke Incorporation Rate
12 Na 0.017 ion exchange120
Na 0.021 ion exchange250
13 Na 0.054 ion exchange375
Na 0.095 ion exchange420
14 K 0.048 ion exehange430
K 0.071 ion exchange605
Ca 0.015 ion exchange150
Ca 0.047 ion exchange595
16 Na ,019 Physical ~d-34
mixture
17 Na ,028 Physical Ad-94
mixture
18 K ,018 Physieal Ad-ll9
mixture
19 K ,028 Physieal Ad-214
mixture
Ca ,018 Physical Ad-17
mixture
21 None -- None lO
22 The data clearly indieate that the gasification rate is
23 significantly increased with increased concentration of
24 both alkali and alkaline earth metal cations. The data
also show that calcium, which is known to be relatively
26 non-catalytie when incorporated by physical admixture,
27 becomes quite aetive, catalytieally, when the same is incor-
~a porated via ion exchange. This discovery is, of course,
29 quite surprising. The data also show that when the eations
are incorporated via ion exchange, even with the alkali
31 metal eations that do impart eatalytie aetivity when phy-
~1
,,,
1 sically admixed, the catalytic activity is improved.
2 While the present invention has been described and
3 illustrated by reference to particular embodiments thereof,
4 it will be appreciated by those o~ ordinary skill in the art
that the same lends itself to variations not necessarily
illustrated herein. For this reason, then, reference
should be made solely to the appended claims ~or purposes
of determining the true scope of the present invention.
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