CA1068666A - Pyrolyzed ion exchange resins containing metal salts - Google Patents

Abstract

The present invention provides partially pyrolyzed particles of a macroporous synthetic polymer having properties suitable for catalysis and a resistance to crushing and particle sloughage greater than that of known spherical adsorbent particles or that of granular activated carbon, comprising the product of controlled thermal degradation of a macroporous synthetic polymer containing a carbon-fixing moiety and a catalytic metal, and derived from one or more ethylenically unsaturated monomers, or monomers which may be condensed to yield macroporous polymers, or mixtures thereof, which partially pyrolyzed particles have: (a) at least 85% by weight of carbon; (b) multimodal pore distribution with macropores ranging in size from about 50 .ANG. to about 100,000 .ANG. in average critical dimension; and micropores ranging in size from about 4 .ANG. to about 50 .ANG. in average critical dimension; (c) a carbon to hydrogen atom ratio of between about 1.5:1 and about 20:1; and (d) up to 15% by weight of a metal. These partially pyrolyzed particles are useful as adsorbents in both gaseous and liquid media to remove impurities therefrom, and are also useful as catalysts in industrial and laboratory applications.

Description

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Disclosure ::, ..
This invention concerns partially pyrolyzed ;~
particles of resinous polymers, methods of their pyrolysis, applications for removing impurities such as sulfur -compounds, monomers, and other industrial contaminants ` or pollutants from gases and purifying pollutant-containing - liquid streams such as phenolics from waste streams and barbiturates from blood. Particularly the invention concerns partially pyrolyzed macroreticular materials -as adsorbents for vinyl chloride removal, blood purifi-cation, phenolic recovery and, when metals are incorporated, ; particularly as catalytic agents for industrial and :~ laboratory processes.
¦ The most commonly used adsorbent today is activated carbon. The production of activated carbon for x ~-~ ~ , `~` industrial purposes employs a wide variety of carbonaceous ~$i ~, starting materials such as anthracite and bituminous coal, coke, carbonized shells, peat, etc. Sui~ability of such materials depends on a low ash content and availability ~ ~
in a uniform and unchanging quality. -; ~ .. , ~ .
Methods of activation can be considered in two ~.-'` categories. The first category includes "chemical ~ ;
activation" processes, in which the carbonaceous mate~
rials or sometimes the chars are impregnated with one ~
~t; or more activating agents such as zinc chloride, alkali ~ ;
carbonates, sulphates, bisulphates, sulfuric or phosphoric acid and then pyrolyzed (carbonized). The action of ' '`' '"''" ' ~'.-.

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these materials appear to be one of dehydration with high yields of carbon unaccompanied by tarry materials.
The second category includes processes known as "heat treatment" in which chars are heated to temperatures between 350 and 1,000C in the presence of CO2, ~2' 2' ', ~ICl, C12, H2O and other gases. A portion of the char ` `
; is burned as the surface area and "activity" of the carbon ` increases. Via careful control of activation parameters, -manufacturers are today able to produce high surface area `~ 10 products (800-2,000 M /g) in a wide range of uniform ~; particle sizes.
Production o~ activated carbon by the above ^
processes gives materials with the highest available carbon capacities for a wide variety of adsorbates in both the liquid and gas phases. However, these materials `
possess the following disadvantages:
a) difficult and expensive thermal regeneration b) high regeneration losses of 10~/cycle ,; c) friability of active carbon particles `
d) lack of control of starting materials ` Adsorbents produced according to the invention `` via pyrolysis of synthetic organic polymers are prefer-~` ably spheres which possess a great deal of structural in-tegrity. They do not easily break apart or slough dust -~ ;
: particles as is the case for active carbon. secause of ; this lack of friabi`lity, the regenerative losses are fre- `
~. ,, quently lower than is common for active carbon.
;`~ Pyrolysis of synthetic organic polymers further ~` ";
.~ , .
;~ allows a much greater degree of control of the starting ~ , , .
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materials and hence of the final product than is possible with naturally occurring raw materials used for production of activated carbons.
Incorporation of desirable elements and functional groups to enhance absorbency for specific adsorbates is easily achieved. Control of the average pore size and pore size distribution is much more easily achieved with well defined ; synthetic starting materials. This increased control allows . the production of adsorbents designed for specific adsorbates with adsorbent capacities far greater than is possible with ~ -activated carbons.
The present invention provides partially pyrolyzed ~
particles, preferably in the form of beads or spheres, produced ;
by the controlled decomposition of a synthetic polymer of , ' specific initial porosity. In a preferred embodiment, the pyrolyzed particles are derived from the thermal decomposition ' of macroreticular ion exchange resins containing a macroporous '~ -~i structure. ~
According to the present invention as disclosed and ~ ~ -claimed herein, there are provided partially pyrolyzed particles ~ ~ -of a macroporous synthetic polymer having properties suitable for catalysis and a resistance to crushing and particle ",?" .;.. , " :
sloughage greater than that of known spherical adsorbent .;~
particles or that of granular activated carbon, comprising ~ .
the product of controlled thermal degradation of a macroporous synthetic polymer containing a carbon-fixing moiety and a -:~ catalytic metal, and derived from or more ethylenically j` --; - ;
~` unsaturated monomers, or monomers which may be condensed to - yield macrOpQrous polymers, or mixtures thereof, which ~ -~

partially pyrolyzed particles have: (a) at least 85~ by weight of carbon; (b) multimodal pore distribution with .' ~ ~S~ ~,' ' :, , ,~ .', :. :' `~-;3 . `; ': ' :- la68666 `~
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macropores ranging in size from about 50 A to about 100,000 A
in average critical dimension; and micropores ranging in size ,-O O
from about 4 A to about 50 A in average critical dimension; (c) a carbon to hydrogen atom ratio of between about 1.5:1 and -:
,: .
àbout 20:1; and (d) up to 15% by weight of a metal.
j In general pyrolysis comprises subjecting the starting polymer to controlled temperatures for controlled periods of -~
` time under certain ambient conditions. The primary purpose of pyrolysis is thermal degradation while efficiently removing "~
i :: 10 the volatile products produced. .
The maximum temperatures may range from about 300C to up . to about 900C, depending on the polymer to be treated and ^, the desired composition of the final '.: ,, `':.~ . :

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pyrolyzed particles. Higher temperatures, e.g., about 700C and higher, result in extensive degradation of the polymer with the formation of molecular sieve sized pores in the praduct.
Most desirably, thermal decomposition (alternatively denoted "pyrolysis" or "heat treatment") is conducted in an inert atmosphere comprised of, for example, argon, neon, helium, nitrogen, or the like, using beads of macroreticular synthetic polymer substituted ` ~
with a carbon-fixing moiety which permits the polymer to ~; -char without fusing in order to retain the macroreticular structure and give a high yield of carbon. Among the suitable carbon-fixing moieties are sulfonate, carboxyl, ~;
amine, halogen, oxygen, sulfonate salts, carboxylate salts and quaternary amine salts. These groups are intro-.. j, . . .
duced into the starting polymer by well-known conventional techniques, such as those reactions used to functionalize : ' ! `
; polymers for production of ion exchange resins. Carbon-fixing moieties may also be produced by imbibing a reactive precursor thereof into the pores of macro-~` reticular polymer which thereupon, or during heating, ., chemically binds carbon-fixing moieties onto the polymer.
Examples of these latter reactive precursors include sulfuric acid, oxidizing agents, nitric acid, Lewis `- ;
; acids, acrylic acid, and the like. `~
Suitable temperatures for practicing the -process of this invention are generally within the ~ -` range of 300C to about 900C, althoughhigher tempera-., ~',: " .
tures may be suitable depending upon the polymer to be '~ 30 treated and the desired composition of the final , , , '` , ". ~' .:: . ' ' ' ` `' ' :
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pyrolyzed product. At temperatures above about 700C
the starting polymer degrades extensively with the formation of molecular sieve sized pores in the product, i.e., about 4 - 6 A average critical dimension, yielding a preferred class of adsorbents according to this invention. At lower temperatures, the thermally-formed pores usually range from about 6 A to as high as O
50 A in average critical size. A preferred range of ~`~
~, . .
pyrolysis temperatures is between about 400C and 800C.
: 10 As will be explained more fully hereinafter, temperature .: :,,, control is essential to yield a partially pyrolyzed ~ ;
material having the composition, surface area, pore -structures and other physical characteristics of the .,, desired product. The duration of thermal treatment is relatively unimportant, providing a minimum exposure :
time to the elevated temperature is allowed.
~;j By controlling the conditions of thermal `r ~ decomposition, in particular the temperature, the elemental composition, and most importantly, the carbon to hydrogen atom ratio (C/H), of the final product ~;
~`` particles is fixed at the desired composition.
- Controlled heat treatment yields particles intermediate -~
. ~ .~, .
~,r, in C/H ratio composition between activated carbon and ` the known polymeric adsorbents. ~ -The following table illustrates the effect of .::,, :-maximum pyrolysis temperature on the C/H ratio of the ;~
final product, utilizing macroreticular functionalized ~ .. ~ . . . .
~ polymers as the starting materials.

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Table I
'' Starting MaterialMaximum Pyrolysis C/H Ratio .
CompositionTemperature of Product .
(1) Styrene/Divinylbenzene ~
copolymer adsorbent ~:
: (control) . ~ :.. ..

(2) Styrene/divinylbenzene ~ .~
ion exchange resin ~ -,, with sulfonic acid : :
functionality (H+form) 400C 1.66

(3) Same as (2) 500C 2.20

(4) Same as (2) 600C 2.85 ~ ~ :
. ,: :

(5) Same as (2) 800C 9.00 ~. :..... ,::.: ~
: (6) Activated carbon ~negligible hydrogen) .: ~.. '' ~ ' -.:
- A wide range of pyrolyzed resins may be :
produced by varying the porosity and/or chemical compos~
ition of the starting polymer and also by varying the .. ~.
conditions of thermal decomposition. In general, the . - .
pyrolyzed resins of the invention have a carbon to : . : ::
hydrogen ratio of 1.5 : 1 to 20 : 1, preferably 2.0 : 1 , . .
to 10 : 1, whereas activated carbon normally has a .
C/H ratio much higher, at least greater than 30 : 1 (Carbon and Graphite Handbook, Charles L. Mantell, ''r"' '' ' Interscience Publishers, N. Y. 1968, p. 198). The :;
product particles contain at least 85% by weight of carbon with the remainder being principally hydrogen, alkali metals, alkaline earth metals, nitrogen, :
oxygen, sulfur, chlorine, etc., derived from the polymer .`;~
or the functional group (carbon-fixing moiety) contained ~:.
thereon and hydrogen, oxygen, sulfur, nitrogen, alkali .. . .
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metals, transition metals, alkaline earth metals and other elements introduced into the polymer pores as components of a filler (may serve as a catalyst and/or carbon-fixing moiety or have some other functional purpose).
The pore structure of the final product must contain at least two distinct sets of pores of differing -average size, i.e., multimodal pore distribution.
The larger pores originate from the macroporous resinous starting material which preferably contain macropores -ranging from between about 50 to about 100,000 Angstroms in average critical dimension. The smaller pores, as mentioned previously, generally range in size from about 4 to about 50 A, depending largely upon the maximum temperature during pyrolysis. Such multimodal pore distribution is considered a novel and essential ~`` characteristic of the composition of the invention.
The pyrolyzed polymers of the invention have : :.
relatively large surface area resulting from the macroporosity of the starting material and the .,`','. ' r~ .
.. , :
smaller pores developed during pyrolysis. In general the overall surface area as measured by N2 adsorption ranges between about 50 and 1500 M2/gram. Of this, . . . .
the macropores will normally contribute about 6 to ;~
about 700 M2/gram, preferably 6 - 200 M2/g, as calculated by mercury intrusion techniques, with the remainder contributed by the thermal treatment. Pore-~ .
free polymers, such as "gel" type resins which havè been subjected to thermal treatment in the prior art ~see, e.g., :.,., ; .
.,,` :: ' . ~ . . . .
9 _ .. ~

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- 1~68~66 East German Patent No. 27,022, February 12, 1964 and No. 63,768, September 20, 1968) do not contribute the large pores essential to the adsorbents of the invention nor do they perform with the efficiency of .: . -the pyrolyzed polymers described herein. The following table illustrates the effect of macroporosity on ;
product composition: ~ ~

Table II ~ ` ;

Adsorbents from sulfonated styrene/divinyl 10benzene copolymers*with varying macroporosity After Before Pyrolysis Pyrolysis . .
Surface SamplePolymer %Aver.pore area Surface No. type DVEisize A (M2/g) area 1 non-porous 8 0 0 32 2Macroporous 20 300 45 338 3 " 50approx.100 130 267 4 " 80 50 570 570 ~`
, . .:,.~,.:
~'i 5 " 6~20,000 6 360 * All copolymers were sulfonated to at least 90%
of theoretical maximum and heated in inert - atmosphere to 800C.

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It may be noted from the data of Table II that the ;
final surface area is not always directly related to the porosity of the starting material. The starting surface areas of the macroporous polymers span a ;. ~ ,., . ~ , :
factor of nearly 100 while the heat treated resins only ~ ~
, differ by a factor of about 2. The non-porous "gel"

`~ resin has a surface area well below the range of the ~;

~ 30 starting materials of the invention and yielded a ,: :
;` :`
`, ',, .
` ' ''~,' "'. ' : ;
~;a61~66 product with surface area substantially below the heat treated macroporous resin.
The duration of pyrolysis depends upon the time ' needed to remove the volatiles from the particular -., :- . .
polymer and the heat transfer characteristics of the method selected. In general, the pyrolysis is very rapid when the heat transfer is rapid, e.g., in an oven where a shallow bed of material is pyrolyzed, or ` in a fluidized bed. To prevent burning of the pyrolyzed `~
polymer, normally the temperature of the polymer is reduced to not more than 400C, preferably not more than 300C, before the pyrolyzed material is exposed to air.
The most desirable method of operation involves rapid heating to the maximum temperature, holding the temperature at the maximum for a short period of time (in the order of 0 - 20 minutes) and thereafter quickly ,; : .
reducing the temperature to room temperature before exposing the sample. Products according to the invention -: ~ .
have been produced by this preferred method by heating ;to 800C and cooling in a period of 20 - 30 minutes.
; ~onger holding periods at the elevated temperatures are also satisfactory, since no additional decomposition appears to occur unless the temperature is increased.
~`- Activating gases such as CO2, NH3, 2~ H20 or combinations thereof in small amounts tend to react with the polymer during pyrolysis and thereby increase the surface area of the final material. Such gases are ;
~` optional and may be used to obtain special characteristics `~ of the adsorbents.
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~6~666 The starting polymers which may be used to ~ `~
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produce the pyrolyzed resins of the invention include ; ~ ;
macroreticular homopolymers or copolymers of one or `
more monoethylenically or polyethylenically unsaturated monomers or monomers which may be reacted by condensation to yield macroreticular polymers and copolymers. The macroreticular resins used as precursors in the formation of macroreticular heat treated polymers are not claimed as new compositions of matter in themselves. Any of the known materials of this type with an appropriate carbon-fixing moiety is suitable. The preferred monomers are those aliphatic and aromatic materials which are ~;
; ethylenically unsaturated.
.~ . .
Examples o~ suitable monoethylenically unsat-` urated monomers that may be used in making the granular `

;` macroreticular resin include: esters of acrylic and ~ :

methacrylic acid such as methyl, ethyl, 2-chloro ethyl, ` propyl, isobutyl, isopropyl, butyl, tert-butyl, sec-butyl, ; .
ethylhexyl, amyl, hexyl, octyl, decyl, dodecyl, cyclohexyl, .

isobornyl, benzyl, phenyl, alkylphenyl, ethoxymethyl, '-~

;; ethoxyethyl, ethoxypropyl, propoxymethyl, propoxyethyl, !``. .: :
'~ propoxypropyl, ethoxyphenyl, ethoxybenzyl, ethoxycyclo- ;-~

hexyl, hydroxyethyl, hydroxypropyl, ethylene, propylene, ~ -, , .
isobutylene, diisobutylene, styrene, ethylvinylbenzene, vinyltoluene, vinylbenzylchloride, vinyl~chloride, `~ vinyl acetate, vinylidene chloride, dicyclopentadiene, ` acrylonitrile, methacrylonitrile, acrylamide, methacryl- ;
amide, diacetone acrylamide, functional monomers such as - ~
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1~68666 . ..
I vlnylbenzene, sulfonic acid, vinyl esters, including ~.
vinyl acetate, vinyl propionate, vinyl butyrate, vinyl laurate, vinyl ketones including vinyl methyl ketone, vinyl ethyl ketone, vinyl isopropyl ketone, vinyl n-butyl ketone, vinyl hexyl ketone, vinyl octyl . .
ketone, methyl isopropenyl ketone, vinyl aldehydes including acrolein, methacrolein, crotonaldehyde, vinyl .-: :
ethers including vinyl methyl ether, vinyl ethyl ether, : ' vinyl propyl ether, vinyl isobutyl ether, vinylidene compounds including vinylidene chlorlde bromide, or :,! ,~'' ' bromochloride, also the corresponding neutral or .
: half-acid half-esters or free diacids of the unsaturated .. dicarboxylic acids including itaconic, citraconic, aconitic, fumaric, and maleic acids, substituted , : acrylamides, such as N-monoalkyl, -N,N-dialkyl-, and N-dialkylaminoalkylacrylamides or methacrylamides where the alkyl groups may have from one to eighteen carbon atoms, such as methyl, ethyl, isopropyl, butyl, hexyl, cyclohexyl, octyl, dodecyl, hexadecyl and octadecyl : . .
aminoalkyl esters of acrylic or methacrylic acid, .~ such as ~-dimethylaminoethyl, K-diethylaminoethyl or ~ ~;
. 6-dimethylaminohexyl acrylates and methacrylates, . alkylthioethyl methacrylates and acrylates such as ethylthioethyl methacrylate, vinylpyridines, such as .~:
` 2-vinylpyridine, 4-vinylpyridine, 2-methyl-5-vinyl-pyridine, and so on. .

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`~` - 13 -, ' .'' ~., ~, ~ "'' '' ' ' 1068666 :~

In the case of copolymers containing ethylthioethyl methacrylate, the products can be ~
oxidized to, i~ desired, the corresponding sulfoxide ` ;
~ or sulfone.
Polyethylenically unsaturated monomers which ordinarily act as though they have only one such unsaturated group, such as isoprene, butadiene, and chloroprene, may be used as part of the monoethylenically -. ~ : .
. unsaturated category.
Examples of polyethylenically unsaturated -~
; compounds include: divinylbenzene, divinylpyridine, divinylnaphthalenes, diallyl phthalate, ethylene glycol diacrylate, ethylene glycol dimethacrylate, trimethylolpropanetrimethacrylate, divinylsulfone, `
polyvinyl or polyallyl ethers of glycol, of glycerol, or pentaerythritol, of diethyleneglycol, of monothio . or dithio-derivatives of glycols, and of resorcinol, ;;
divinylketone, divinylsulfide, allyl acrylate, diallyl :~ maleate, diallyl fumarate, diallyl succinate, diallyl ``` 20 carbonate, diallyl malonate, diallyl oxalate, diallyl . , - .
adipate, diallyl sebacate, divinyl sebacate, diallyl ~
tartrate, diallyl silicate, triallyl tricarballylate, .
.`-` triallyl aconitate, triallyl citrate, triallyl phosphate, `~: N,N'-methylenediacrylamide, N,N'-methylenedimethacryl- - :
amide, N,N~-ethylenediacrylamide, trivinylbenzene, ::`~
trivinylnaphthalenes, and polyvinylanthracenes. .: .
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A preferred class of monomers of this type are aromatic ethylenically unsaturated molecules such as styrene, vinyl pryridine, vinyl naphthalene, vinyl tol-uene, phenyl acrylate,-vinyl xylenes, ethylvinylbenzene.
Examples of preferred polyethylenically unsatu-rated compounds include divinyl pyridine, divinyl naphthalene, divinylbenzene, trivinylbenzene, alkyldi- ~;
vinylbenzenes having from 1 to 4 alkyl groups of 1 to 2 carbon atoms substituted in the benzene nucleus, and alkyltrivinylbenzenes having 1 to 3 alkyl groups of 1 to 2 carbon atoms substituted in the benzene nucleus. sesides the homopolymers and copolymers of these poly(vinyl) benzene monomers, one or more of them may be copolymerized with up to 98% (by weight of the total monomer mixture) of (1) monoethylenically unsaturated monomers, or (2) .... .
polyethylenically unsaturated monomers other than the poly(vinyl)benzenes just defined, or (3) a mixture of (1) and (2). Examples of the alkyl-substituted di-~and tri-vinyl-benzenes are the various divinyltoluenes, the divinylbenzenes, divinylethylbenzenes, 1,4-divinyl- 2,3,5,6-tetramethylbenzene, 1,3,5 - trivinyl - 2,4,6 - trimethyl-benzene, 1,4-divinyl, 2,3,6 - triethylbenzene, 1,2,4 -trivinyl - 3,5 - diethylbenzene, 1,3,5-trivinyl-2-.- .. .
methylbenzene.

Most preferred are copolymers of styrene, divinyl-benzene and ethylvinyl benzene.

Examples of suitable condensation monomers . . .
~ include: (a) aliphatic dibasic acids such as maleic acid, ~
.. . .
~ fumaric acid, itaconic acid, l,l-cyclobutanedicarboxylic . .
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acid, etc.; (b) aliphatic diamines such as piperazine, 2-methylpiperazine, cls, cis-bis (4-aminocyclohexyl) methane, metaxylylenediamine, etc.; (c) glycols such as diethylene glycol, triethylene glycol, 1,2-butanediol, `~
neopentyl glycol etc.; (d) bischloroformates such as cls and trans - 1,4-cyclohexyl bischloroformate, 2,2,2,4-tetramethyl-1,3-cyclobutyl bischloroformate and -:, .: ., bischloroformates of other glycols mentioned above, etc.;
(e) hydroxy acids such as salicylic acid, _~ and p-hydroxy-benzoic acid and lactones, derived therefrom such as the propiolactones, valerolactones, caprolactones, etc.; (f) diisocyanates such as cls and trans - cyclo-propane -1, 2-diisocyanate, cis and trans-cyclobutane-l-2-diisocyanate etc.; (g) aromatic diacids and . ~
their derivatives (the esters, anhydrides and acid - ;
chlorides) such as phthalic acid, phthalic anhydride, terephthalic acid, isophthalic acid, dimethylphthalate, etc.; (h) aromatic diamines such as benzidine, 4,4'-`~ methylenediamine, bis (4-aminophenyl) ether, etc.;
~ 20 (i) bisphenols such as bisphenol A, bisphenol C, ... .
bisphenol F, phenolphthalein, resorcinol, etc.; (j) bisphenol bis(chloroformates) such as bisphenol A : -bis(chloroformate), 4,4'-dihydroxybenzophenone bis(chloroformate) etc.; (k) carbonyl and thiocarbonyl compounds such as formaldehyde, acetaldehyde, thioacetone, ;
actone, etc.; (1) phenol and derivatives such as ~`
;: .. : : .
phenol, alkylphenols, etc.; (m) polyfunctional cross- ;

" linking agents such as tri or poly basic acids such as ' trimellitic acid, tri or polyols such as glycerol, `; 30 tri or polyamines such as diethylenetriamine; and other ~ condensation monomers and mixtures of the foregoing.
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Ion exchange resins produced from aromatic ;-and/or aliphatic monomers provide a preferred class of starting polymers for production of porous adsorbents.
The ion exchange resin may also contain a functional group selected from cation, anion, strong base, weak base, sulfonic acid, carboxylic acid, oxygen containing .,,~ ," ~ .
, halogen and mixturesof the sarne. Further, such ion ~' exchange resins may optionally contain an oxidizing agent, a reactive substance, sulfuric acid, nitric acid, acrylic acid, or the like at least partially .... ~ . .
; filling the macropores of the polymer before heat , treatment.

The synthetic polymer may be impregnated with -~

a filler such as carbon black, charcoal, bonechar, ~; sawdust or other carbonaceous material prior to , , .
: pyrolysis. Such fillers provide an economical source ; of carbon which may be added in amounts up to about 90% by weight of the polymer.

The starting polymers, when ion exchange ; 20 resins, may optionally contain a variety of metals in ,, ~.
their atomically dispersed form at the ionic sites.
These metals may include iron, copper, silver, nickel, manganese, palladium, cobalt, titanium, zirconium, ; sodium, potassium, calcium, zinc, cadmium, ruthenium, uranium and rare earths such as lanthanum. By utillzing i the ion exchange mechanism it is possible for the , ,.,. ~ .
skilled technician to control the amount of metal that is to be incorporated as well as the distribution.
Although the incorporation of metals onto the . ~ . .. .
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resins is primarily to aid their ability to serve as ; catalytic agents, useful adsorbents may also contain metal.
; Synthetic polymers, ion exchange resins whether in the acid, base or metal salt form are ~;
; commerically available. According to the invention there is also provided an adsorption process for separating components from a gaseous or liquid medium which comprises contacting the medium with particles of a pyrolyzed synthetic polymer. -` For example it has been discovered that a styrene- ;
divinylbenzene based strongly acidic exchange resin pyro- ;
lyzed from any of tha forms of Hydrogen, Iron (III), .:: ... ... :
Copper(II), Silver(I) or Calcium(II) can decrease-the ~;
concentration of vinylchloride in air, preferably dry air, from an initial concentration of 2 ppm - 300,000 ppm to a level of less than 1 ppm at flow rates of 1 bedvolume/hour . .~, ~` to 600 bedvolume/min., preferably 10 - 200 bedvolume/minute. ,,~
Compared to activated carbon the adsorbents of ~20 the invention show advantages such as a lower heat of adsorption, less polymerization of adsorbed monomers on , the surface, less regenerant required due to diffusion `i`
kinetics, less loss of capacity upon multicycling and ;~
lower leakage before breakthrough. Similar performances ` have been noticed when other impurities such as SO2 and ~-j H2S are removed. The adsorbents of the invention are l-~
J'` particularly useful in the air pollution abatement field to remove components such as sulfur containing molecules, halogenated hydrocarbons, organic acids, aldehydes, ,~0 alcohols, ketones, alkanes, amines, ammonia, acrylo-.~ .

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nitrile, aromatics, oil vapors, halogens, solvents, monomers, organic decomposition products, hydrogen cyanide, carbon monoxide and mercury vapors.
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Specific chlorinated hydrocarbons include:
1,2,3,4,10 10-Hexachloro-1,4,4a,5,8 8a-hexahydro-1,4 endo-exo-5, 8-dimethanonaphthalene 2-Chloro-4-ethylamino-6-isopropylamino-s-triazine Polychlorobicyclopentadiene isomers :. Isomers of benzenehexachloride 60% Octochloro-4,7-methanotetrahydroindane Dichloro-2,2-bis-(p-ethylphenyl)ethane 1,1,1-Trichloro-2,2-bis(p-chlorophenyl)ethane . Dichlorodiphenyl dichloroethylene . . :
` 1,1-bis(p-Chlorophenyl)-2j2,2-trichloroethanol ; 2,2-Dichlorovinyl dimethyl phosphate .
. 1,2,3,4,10, 10-Hexachloro-6, 7-epoxy-1,4,4a,5,6-~` 7 dimethanonaphthalene `~ 1,2,3,4,10, 10-Hexachloro-6, 7-epoxy-1,4,4a,5,6,7,- :.
.~ 8,8a-octahydro-1,4-endo-endo-5,8-dimethano-~ 20 naphthalene ::; 74% 1,4,5,6,7,8 8a-Heptachloro-32,4,7a-tetrahydro- ~-~
-` 4, 7-methanolndene . 1,2,3,4,5,6-Hexachlorocyclohexane - 2,2-bis(_-Methoxyphenyl)-l,l,l-trichloroethane ~ ~ .... .
. Chlorinated camphene with 67-69~ chlorine ,` ~

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... .

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Other components which may be adsorbed from liquids by ` the adsorbents of the invention include chlorinated `;
phenols, nitro phenols, surface active agents such as detergents, emulsifiers, dispersants and wetting agents, ., :,... .
hydrocarbons such as toluene and benzene, organic and inorganic dye wastes, color bodies from sugars, oils and fats, odorlferous esters and monomers.
The adsorbents when exhausted may be regenerated.
The particular regenerant most suitable will depend on ;., . ::. . :.
the nature of the adsorbed species, but in general will -include brine, solvents, hot water, acids and steam. `;--The thermal regenerability of the adsorbents cons~itutes a distinct advantage. -Adsorbents Without Activation `
Superior adsorbents are produced by this `
invention without the necessity of "activation" common `~
to many carbonaceous adsorbents designated "active carbon". Adsorbents with properties both superior to and different from all other adsorbents are produced directly ~ 20 in one step by heat treating polymers as described above. `
r`- Activation with reactive gases is an optional process `~ sometimes desirable for the modification of adsorbent i~-~
`.` properties but is not a necessary part of the invention.
As shown in Tables III and IV below, the adsorption properties are markedly influenced by the maximum temperature to which the resin is exposed. As shown in Table III a temperature of 500C produces an ;;~
adsorbent which is optimum for chloroform removal from water.

", ~ ......
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; - 20 -. . - , . .
,, . :.
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~L068666 Resins heat treated to 800C are capable of selectively adsorbing molecules according to size ;
(see Table IV). The 800C example is even more effective in selecting for hexane over carbon tetra- -chloride than indicated in Table IV since nearly all of the CC14 is adsorbed on the surface of the macropores and not in the micropores. The apparently superior selectivity oE the commercial carbon molecular sieve (example 5) is clearly due to much less surface area in the macropores. The resin heat treated to 500C
(No. 1 in Table IV) shows much less selectivity for .. :
the two different sized molecules, emphasizing the impor-; tant inEluence that the maximum temperature during heat treatment has on adsorbent properties.

Table III
, Equilibrium Aqueous Chloroform Capacities ~, for Various Adsorbents All adsorbents in equilibrium with 2 ppm CHC13 in deionized water at room temperature. -No. Sample Equilibrium Capa-citv @ 2 ppm -- - :
` 1S/DVB polymeric adsorbent6.0 mgjg dry -~
absorbent ~:
~` 2Pittsburgh Granular Activated Carbon 10.2 ~;

, 3Sulfonated S/DVB resin ~ -.~ pyrolyzed to 800C 21 ' ;

4Same as No. 3 but oxygen ;, activated 28 '~ ~

~; 30 5Same as No. 3 pyrolyzed ~ - ' to 500C 45 '~j` *S/DVB = Copolymer of styrene and divinylbenzene : ~ . .. : .
.,. ~ . .

`` ~ - 21 - ',~;
. . .
: ~ .. :. .; .-': . ..... :.

. ^`. ` ::: ~
~: 1068IEi66 ~ ~ -,i.-' ~ , .
` Table IV

Molecular Screening Determination via -Equilibrium Vapor Uptake .. ~ . . .:
Capacity (~l/g) No.Sample CC141Hexane2 ;

; 1Sulfonated S/DVB pyrolyzed to 500C 12.1 15.6 ., :
2Same as No. 1 pyrolyzed to 800C 3.4 15.7 . ~ .... : .
10 3Pittsburgh Activated Carbon 41.0 40.9 ' 4Same as No. 2 oxygen etched 17.6 22.7 ;~

;~i 5Carbon molecular sieve from ~--Takeda Chemical Industries 0.50 12.1 ' - ;

; 1 Effective minimum size 6.1A
- 2 Effective minimum size 4.3A ,~

`; The following examples serve to illustrate but not ,ii" limit the invention.

Example 1.

A 40 g sample of "Amberlite 200" (Registered Trademark of Rohm and Haas Company for a styrene/DVs sulfonic acid ion exchange resin) in the Na+ form ~, : .
1~ (49.15~ solids) was placed in a filter tube and washed ` -,~ with 200 cc of D. I. H2O. 20 g of FeC13-6H2O were ~ dissolved in about 1 1 of D.I. H2O and passed through `,~ the resin sample in a columnar manner over a period of -~
about four hours. Uniform and complete loading could be observed visually. The sample was then washed with 1 1 of D. I. H2O, aspirated for 5 minutes and air dried for 18 hours.
:, . ~ . .
~, 30 10 grams of this sample was then pyrolyzed together with several other samples in a furnace equipped for input of 7 1 of argon gas per minute. The sample ~; was raised to a temperature of 706C over a period of 6 hrs. `~

:
.... ~ .

~ 3666 with step increases of about 110C each hour. The sample was held at the maximum temperature for 1/2 hour. The power to the furnace was shut off and the furnace and contents were allowed to cool undisturbed to room temperature with the argon flowing continuously over the next 16 hours.
The yield of solid material was 43% after pyrolysis. The physical characteristics of this sample are listed in Table V along with the data for Samples B through G, and I through K which were prepared in the same manner.
Example 2 ; The technique of example I is modified in that ~
250 gm of "Amberlite 200" in hydrogen form (obtained by `
converting the sodium form with hydrochloric acid) is ~ pyrolyzed by raising the temperature continuously over `` six hours to 760C. The sample is then allowed to cool over the next twelve hours after which it shows a surface area of 390 m2/g.
~, Process Examples `` Adsorption of Vinyl Chloride ,j: ; - . . :
` 20 Ten cubic centimeters of sample are placed in a 1.69 centimeter inner diameter stainless steel column.

The bed depth is then 5.05 centimeters. Through the use `-~ of a dilution device with a mixing chamber, a gas stream `

' of 580 ppm vinyl chloride in air is generated and passed through the column at a volumetric flow rate of 800 ml/min.
: ::::: :
~, The column flow rate is therefore 80 bed volumes/minute.

All experiments are conducted at ambient temperature and -a pressure of 16 psig. A flow of 10 ml/min is diverted : ~ :
~ from the effluent and fed into a flame ionization detector ;

,`; 30for continuous vinyl chloride analysis. Conventional Rohm , ~-. :" .

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and Haas adsorbents and a Calgon activated carbon are also tested. The results are shown below.
; Table VI
Adsorption of Vlnyl Chloride on Sample K; H~ Form, Pyrolyzed ~ Elapsed Time Leakage Instantaneous %
;. _ (min) (ppm VCM) Leakage '',', O O O

.: 50 0 0 0 0 :
,~' 10 100 0 0 125 0 o ~ .
~ 150 `
. 166 1 .1 ~j 200 34 5.8 ~.! 225 242 42 `.~j 250 454 78 `~
.j 275 569 98 1 300 580 100 ;~ :

,, ., -. : : : .
. Table VII .
Adsorption of Vinyl Chloride on Sample B, Fe(III) Form, Pyrolyzed and Leached with H2SO4, Bed Volume - 20 cc .. ~ . . : : . :
: Elapsed Time Leakage Instantaneous ;1 (min): (ppm) Leakage .,.i O O O . . . ~ . , .
~ 25 0 o : ; 50 0 0 ~:::. :.
0 0 :,:
~'~ ` 1 0 0 0 0 ' :~ :: ' ' . ': ' :: :' '.
. 109 1 .2 ~: :
~ - 30 125 284 49 '`J~` 150 521 90 ;:.:
.j::. 175 568 98 ~: :
,~ 200 580 100 : :
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~ ''.' ~,' ~ - 25 - -; : :
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.:. ;': :

1~61!~666 Table VIII . ~
; ~ .
iAdsorption of Vinyl Chloride on Sample C, Cu( ) Form, Pyrolyzed _ _ __ Elapsed Time Leakage Instantaneous %
(min) (ppm VCM) Leakage .
. . _ .
O O O .

o o 100 0 0 : :
125 0 0 ?.
. 143 1 0.2 .. 150 2 0.4 .
. 175 68 12 j 200 244 42 .
i 225 401 69 . 250 501 86 : -. 300 580 100 :, . , .`, ;.' . :~
Table IX
.. Adsorption of Vinyl Chloride on Sample A, Fe(II ) Form, Pyrolyzed ; . .,.~.
iElapsed TimeLeakage~Instantaneous % -. ;.
`.~ (min) (ppm VCM) Leakage , -:.'t ,, :. .
O ::
0 o .:
. 50 0 0 ~ .:
.~ 75 0 0 ;:.
.; 100 0 -'~ 30125 2.0 0.3 :
~ 150 26 4.5 -:
.- 175 ~ 112 19 ~ 200 303 52 .
.~; 116 1 0.2 ~, -: ' ;~, ...
.,.~ . , . ::
. ~ ~ . - ,. . .
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. !

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11:)6866~
, . I .
.
, -, Table X
.~.
' Adsorption of Vinyl Chloride on "Pittsburgh PCB"* 12 x 30 Activated Carbon . ' ' .
Elapsed Time Lèakage Instantaneous ' (min) (ppm) Leakage ', O O O ,.

;~ 75 0 0 , ~ 10 100 0 0 '.' .' 115 0 o 117 1 0.2 t'~ 200 580 100 Further Process Examples The adsorption is performed with a bed of 9.5 cc of ; ;
; Resin J which is subjected to a vinyl chloride influent -~
~,, stream containing 350 ppm and having a flow rate of 160 bed 'A`, volumes per minute. Regeneration is carried out using , steam at 130 - 160C for 20 minutes, followed by drying ., ~ ~, . . . .
with air for 10 minutes. The experiment is performed for 15 cycles to show the lack of capacity loss over several ~' cycles. Results are shown in the following table.
~ : .: : .
, j , ~ .
Table XI
Cycle Time** Volume Capacity Weight Capacity ;
` 1 45 6.9 11.1 :` 3 42 6.4 10.3 49 7.5 12.1 -7 45 6.9 11.1 ~
9 45 6.9 11 1 -.. , -11 37 5.6 9 0 ~` 13 40 6.1 9.8 ' ;, 15 45 6.9 11.1 ** Elapsed time at 1 ppm leakage in minutes ...

* Calgon Corporation's trademark for a type of activated ` carbon. ;
- .
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The results of comparative experiments on other commercial , . . .
resins and carbon are shown in the following table. j;
.
Table XII
Volume Capacity Weight Capacity Adsorbent (mg/cc) (mg/gm) Sample D 14.4 13.5 Sample F 9.8 13.1 Sample G 2.9 3.2 -"Pittsburgh BPL"* 12 x 30 Activated Carbon 8.5 17.0 , "Kureha"** Spherical Activated Carbon 13.9 26.7 ~ Sample H(llI) 29.2 47.1 ~
- Sample H(l) 26.6 42.4 -"Pittsburgh PCB" 12 x 30 `~ Carbon(ll) 7.6 16.8 "Pittsburgh( P)CB" 12 x 30 CarbOn lV 11.4 25.3 -;l (1) Run with a 460 ppm influent concentration at 160 BV/min ~ 20 over a 10 cc sample :~ : .
(11) Run with a 350 ppm influent concentration at 160 BV/min `
over a 10 cc sample ~¦ (111) Run with a 1070 ppm influent concentration at -~- 160 BV/min over a I0 cc sample (lV) Run with a 860 ppm influent concentration at 160 BV/min over a 10 cc sample It should be noted that sample H prepared by the procedure . .
of Example II is a preferred embodiment. ~
Sample J when compared to PCB 12 x 30 carbon shows --a smaller drop in capacity when the relative humidity is -~
increased as shown herein below. i r :~ .. , , _ _ Volume_Capac _y mg/cc -:,R. Humidity PCV 12 x 30 Sample J ~;
:~ 0 11.4 6.4 52 9.6 7.4 ;` 60 4.1 4.8 100 -- 2.3 ``` Influent concentration - 850 to 1100 ppm ~ * Trademark `~ **Trademark i: ~, : ;, . .
: - 28 - ~

:~`
;, ;: , ' , -- . ~ ~ : . ~ ' , ~ 10~86$~;
.
Phenol Adsorption 20 cc of Sample I is subjected to an influent concentration of 500 ppm of phenol dissolved in D. I. water.

;'l , , .:
, The flow rate is 4 BV/hr. The sample shows a leakage of less than 1 ppm at 38 bed volumes. The sample's capacity is calculated to be 1.56 lbs./cubic ft. or 25.0 mg/gm at ;
a leakage of 3 ppm.
"Amberlite XAD-4"*, a commercial adsorbent when ;;~
used as a comparison shows a capacity of 0.9 lbs./cubic ft.
`~10 or 14.4 mg/gm at a leakage of 6 ppm.
" ~
Sample I is regenerated with methanol at a rate `~ ;
of 2 BV/hr. and required 5 BV to be 71% regenerated.
Sample B is evaluated for adsorbent capacity for H2S and SO2. The results indicate that significant amounts of both pollutants are adsorbed. Similar measurements for an activated carbon indicate a negligible adsorption of S2 at 100C.
Synthetic organic polymers other than ion exchange ~ resins have been evaluated for adsorbent capacity. A `
`20 sample of polyacrylonitrile crosslinked with 15% divinyl `
benzene has been pyrolyzed under a variety of experimental conditions and evaluated for SO2 adsorbancy. The experi- ~ ~
mental conditions and results are presented in Table XIII. ~ -Once again, significant quantities of SO2 are adsorbed. `~
Example N is of particular interest since an oxidation of , the copolymer in air prior to pyrolysis significantly in-creases the adsorption capacity of the pyrolyzed product ~; for SO2. -.;. 2 * Trademark ;
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.::. . :
Crush Resistance . . . _.. _ . : .
. The physical integrity of beads of pyrolyzed poly- `
mers is greater than that of other spherical adsorbents and .. . .
granular activated carbon as indicated in Table XIV. Superior ~"
resistance to fragmentation is expected to result in a greatly ;.:.: .,... ~ .
i extended useful life compared to granular carbon for which attrition losses can be large. Also the lack of sloughage of particulate matter by the pyrolyzed polymers allows their use ~-; in applicationsfor which activated carbon is unacceptable such as blood treatment.
TABLE XIV
Crush Strength of Macroreticular Pyrolyzed Polymers - ~
` And Other Adsorbents ~ :
DescriptionNo. TypeCrush Strength 1 (Kg~
.; . ~ . .
Sulfonated S/DVB -1 400C 2.3 ~ ;
heat treated under inert at- 2 500C >8.1 2 ' mosphere to in-`~ dicated tempera- 3 600C ~3.4 2 ` 20 ture 4 800C ~3.4 2 ~ ;
1000C 3.6 3 ~
Spherical Acti- ~ 6 "Xureha" 0.93 ~ -` vated Carbon 7 Sample of unknown 0.51 Japanese origin ;
used for blood , ~
treatment experi- ' -ments.
Granular Acti- 8 "Pittsburgh BPL"4 ~0.90 vated Carbon `~
': ':''':. :' ~ss which must be placed on upper of two parallel plates to fragment ~ -particle between plates-average of at least 10 trials.

; Lower limit because at least one particle was not broken at maximum setting of 3.6 Kg.
. .

3No beads were broken at maximum setting.
4Since particles are irregularly shaped, experiment was halted i ` when a corner was knocked off.

~ . .
.:
'.", ',.':

-- ` 1068666 i) Carbon Fixing Moieties , A wide variety of moieties have been shown to ~, cause carbon fixation during pyrolysis. A partial list of moieties and the effectiveness of each is given in Table XV.
The exact chemical nature of the moiety is unimportant since any group which serves to prevent volatilization of the carbon ;
during pyrolysis is satisfactory for the process.
ii) Imbibed Carbon-Fixing Agents , -Filling the pores of a macroreticular copolymer -with a reactive substance prior to pyrolysis serves to pre~
vent volatilization of the carbon in the copolymer. In the case of sulfuric acid the material has been shown to go through a sulfonation reaction during heating which produces a substance similar to the starting material of sample 1 in Table XV. The greater carbon yield obtained via imbibing rather than pres~ulfonation is unexpected indicating the pro- ~
cess may be superior to other techniques of carbon fixation. ~ ; -iii) Impregnated Polymers ,. . .
Impregnation is exemplified in No. 4 of Table XVI ~-`` 20 for which the pores of a carbon black containing S/DVB copoly- ,;
mer were filled with H2SO4 and pyrolyzed. The carbon yield , r" is higher than the corresponding experiment (sample 1) per-`~ formed without the presence of the carbon black. ~ `
!.. ' :
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Example 3 The following experiment produced sample No. 1 in Table XVI.
A sample of 30.79 g of the macroreticular copolymer (20~ DVB/S) was placed in a 30mm O.D. quartz tube suitable for subsequent heat treatment. One end of the tube was blocked with quartz wool and the copolymer was piled on top of the quartz wool with the tube held vertically. Isopropanol, D.I.
~` water and 98% H2SO4 (lQ each) were passed in sequence through the resin over a 1.5 hr. period. Excess H2SO4 was drained ; during a 10 min. hold. Approximately 5.5 g of acid remained in ~`' the pores of the resin. The tube was placed horizontally in a tube furnace and N2 passed through the tube at 4,800 cc/min.
;' During heatings white smoke and then a reddish, pungent smell-, ing oil were emitted from the sample. The final product was black, shiny, free flowing beads roughly the same size as the . I , starting resin.

`1 Example 4 , , :
i The following experiment produced sample 2 of Table -.` j . :
~' 20 XVI.
, } ;:~ , -l A benzoic acid copolymer was prepared fro~ a chloro-methylated resin (20% DVB/S) by nitric acid oxidation. A ~
charge of 20.21 g of the solvent swelled and vacuum dried resin j; ~-~, was placed in a quartz tube plugged at one end with quartz wool.
;~ The tube was held horizontally inside a "Glas-col"* heating ;~
mantle and heated gradually to 800C. over a period of 200 mins. `
~` The sample was cooled to room temperature within about 120 min. ~
.; : .: . .
Nitrogen flowed through the tube during heating at a rate of ;

; 4800 cc/min. White smoke was emitted by the sample during heat-ing. The final product consisted of shiny metallic black beads.

*Trademark ~ 35 ~

. .
.: ,

Claims (8)

The embodiments of the invention in which an exclusive property or privilege is claimed are defined as follows:

1. Partially pyrolyzed particles of a macroporous synthetic polymer having properties suitable for catalysis and a resistance to crushing and particle sloughage greater than that of known spherical adsorbent particles or that of granular activated carbon, comprising the product of controlled thermal degradation of a macroporous synthetic polymer containing a carbon-fixing moiety and a catalytic metal, and derived from one or more ethylenically unsaturated monomers, or monomers which may be condensed to yield macroporous polymers, or mixtures thereof, which partially pyrolyzed particles have:
(a) at least 85% by weight of carbon:
(b) multimodal pore distribution with macropores ranging in size from about 50 .ANG. to about 100,000 .ANG. in average critical dimension, and micropores ranging in size from about 4 .ANG. to about 50 .ANG. in average critical dimension;
(c) a carbon to hydrogen atom ratio of between about 1.5:1 and about 20:1; and (d) up to 15% by weight of a metal.

2. The partially pyrolyzed particles of claim 1 wherein the particles contain up to 15% by weight of one or more alkaline metals, alkaline earth metals, nitrogen, oxygen, sulfur, chlorine, transition metal or mixtures thereof.

3. The partially pyrolyzed particles of claim 1 wherein the particles contain up to about 15% by weight of a metal selected from iron, copper, sulfur, nickel, manganese, palla-dium, cobalt, titanium, zirconium, sodium, potassium, calcium, zinc, cadmium, ruthenium, uranium, and rare earths such as lanthanum.

4. The partially pyrolyzed particles of claim 3 wherein the particles are beads or spheres of approximately the same dimension as ion exchange resins.

5. The partially pyrolyzed particles of claim 1 wherein the surface area of the particles measured by N2 adsorption ranges between about 50 and 1500 M2/g of which the macropores contribute about 6 to about 700 M2/g as determined by mercury adsorption techniques.

6. The partially pyrolyzed particles of claim 1 wherein the carbon to hydrogen atom ratio is between about 2:1 and 10:1.

7. The partially pyrolyzed particles of claim 1 wherein the carbon-fixing moiety is selected from sulfonate, carboxyl, amine, halogen, oxygen, sulfonate salts, carboxylate salts and quaternary amine salts.

8. The partially pyrolyzed particles of claim 3 wherein the carbon to hydrogen atom ratio is at least 9Ø