Ferrisilicate molecular sieve and use as a catalyst

Ferrisilicate molecular sieves of the ZSM-5 type, having SiO.sub.2 /Fe.sub.2 O.sub.3 mole ratios ranging from 20 to 400, are prepared by adding a silica source and a quaternary ammonium salt in that order to an acedified solution of an iron (III) compound, crystallizing the resulting gel to form a ferrisilicate molecular sieve, and thermally treating the molecular sieve with nitrogen, air and/or steam at 300.degree. to 700.degree. C. Preferred thermal treatment comprises treating with nitrogen first, then with air or steam. Thermally treated molecular sieves contain iron both in and outside the crystal framework; most of the non-framework iron is dispersed as very finely divided iron oxides on internal surfaces. Molecular sieves are useful as catalysts in Fischer-Tropsch and other iron oxide-catalyzied reactions.

TECHNICAL FIELD 
This invention relates to processes for making crystalline ferrisilicate 
molecular sieves. More particularly, this invention relates to processes 
for making crystalline ferrisilicate molecular sieves of the ZSM-5 type. 
BACKGROUND ART 
Molecular sieves are ordered, porous crystalline materials having a 
definite three-dimensional crystal structure, within which there are a 
large number of small cavities which are interconnected by a number of 
still smaller channels or pores. These cavities and pores in any specific 
molecular sieve material are of precisely uniform size. Since the pores 
are of such size as to accept for adsorption molecules which are small 
enough to pass through the pores, while rejecting molecules of larger 
size, the materials have come to be known as "molecular sieves" and are 
utilized in various ways which take advantage of this property. Molecular 
sieves may be used, for example, as catalysts, selective adsorbents, 
drying agents, ion exchange materials, and for other purposes. 
Aluminosilicate molecular sieves are frequently referred to as zeolites. 
The synthetic crystalline aluminosilicate zeolites are the best known 
molecular sieves. These materials are characterized by a rigid 
three-dimensional network of SiO.sub.4.sup.- and AlO.sub.4.sup.- 
tetrahedra, which are cross-linked through shared oxygen atoms. The 
electronegativity of the aluminum-containing tetrahedra is balanced by the 
inclusion in the crystal of a cation, typically monovalent or divalent, 
such as an alkali metal (e.g. sodium) or an alkaline earth metal (e.g. 
calcium). The monovalent or divalent ion is typically at least partially 
exchangeable by conventional ion exchange techniques. The aluminum and 
silicon are not exchangeable. Various alumino-silicate molecular sieves 
are known. One of these is ZSM-5, which is described, for example, in U.S. 
Pat. No. 3,702,886 to Argauer et al. 
Less well known are the ferrisilicate molecular sieves. One of these, 
ZSM-12, is described in published European Patent Application (EPA) No. 
0013630. Another is the crystalline silicate described in U.S. Pat. No. 
4,208,305 to Kouwenhoven et al. This latter material is of the ZSM-5 type 
and, according to the patent, consists structurally of a three-dimensional 
network of SiO.sub.4, FeO.sub.4, and optionally AlO.sub.4, GaO.sub.4 and 
GeO.sub.4 tetrahedra which are interlinked by oxygen atoms. The patent 
discloses a number of catalytic processes in which the molecular sieves 
may be used. However, direct conversion of a carbon monoxide-hydrogen 
mixture to a hydrocarbon mixture (the Fischer-Tropsch synthesis) is not 
among these reactions. 
Iron-containing zeolites are also known. These may be prepared by (a) 
physical admixture of a zeolite and an iron component, (b) ion exchange of 
Fe (III) into a zeolite, (c) adsorption of a volatile metal compound in 
the zeolite cavities followed by thermal decomposition, and (d) 
impregnation of a zeolite with a solution of a ferric compound followed by 
thermal decomposition. 
In catalysts where the iron component is physically mixed with the zeolite 
ZSM-5, an intimate mixture between the two components is very difficult to 
obtain. Thus, all of the iron component is likely to be on the outside of 
the pores of the molecular sieve making these catalysts least selective 
for the Fischer-Tropsch reaction. Further, the formation of large metal 
oxide particles decreases the amount of surface available for reactions to 
take place. 
Loss of crystallinity and thermal stability is reported for synthetic 
zeolites which are ion exchanged with ferric ions. The ion exchange of Fe 
(III) cations into the zeolite can give rise to a high dispersion of the 
iron component. However, ion exchanging of Fe (III) ions into the zeolite 
ZSM-5 has not been completely successful, due to the size of the hydrated 
iron complex and the high dispersion of monovalent exchange sites within 
the zeolites. 
Iron (O) (i.e., metallic iron) species can be introduced into the pores of 
a zeolite by adsorption and subsequent decomposition of the iron 
complexes. The most common volatile metal compound that is used to prepare 
iron containing zeolites is iron pentacarbonyl, Fe(CO).sub.5. The size of 
the iron pentacarbonyl is just about ideal to be adsorbed by zeolite Y. 
The iron pentacarbonyl is first adsorbed by the zeolite and then the 
carbon monoxide is driven off from the iron pentacarbonyl by thermolysis. 
This process of making iron containing zeolites has the disadvantage that 
during the process of thermolysis, The adsorbed metal compound tends to 
come out of the pores of the zeolite. Moreover, the iron pentacarbonyl is 
too large in size to enter the zeolite ZSM-5 and hence when used over 
zeolite ZSM-5 will have all of the iron present outside the pores of the 
zeolite ZSM-5. 
DISCLOSURE OF THE INVENTION 
This invention according to a first aspect provides novel crystalline 
ferrisilicate molecular sieves of the ZSM-5 type. These molecular sieves 
have an overall silica to ferric oxide (SiO.sub.2 /Fe.sub.2 O.sub.3) mole 
ratio in the range of about 20 to 400. A first portion of the iron content 
is in the crystal framework or lattice, and the remaining portion of the 
iron is outside the crystal framework. This remaining portions constitutes 
from about 0 to about 80 percent by weight of the total iron content and 
is dispersed in the form of finely divided particles on the internal and 
external surfaces of the molecular sieve. At least about 30 percent, 
preferably at least about 50 percent, most preferably at least about 80 
percent, of the non-framework iron is dispersed on the internal surfaces. 
Nearly all of the non-framework iron on the internal surfaces is in the 
form of iron oxide particles having a particle size less than about 5 
Angstrom units, while iron on the external surfaces is in the form of iron 
oxide particles predominantly from about 5 to about 15 Angstrom units. 
This invention according to a second aspect provides a process for 
preparing ferrisilicate molecular sieves of the ZSM-5 type. This process 
comprises: (a) adding a silica source and one or more compounds selected 
from the group consisting of primary, secondary and tertiary amines and 
quaternary ammonium compounds to an acidic aqueous solution of an iron 
compound, and maintaining said solution in the acidic state until the 
addition of said silica source is complete; (b) heating the mixture 
obtained in step (a) at a temperature of about 100.degree. to about 
250.degree. C. until molecular sieve crystals are obtained; and (c) 
thermally treating the molecular sieve crystals formed in step (b) at a 
temperature from about 300.degree. to about 1000.degree. C. The preferred 
thermal treatment comprises treating the molecular sieve of step (b) in an 
inert atmosphere at about 450.degree. to about 800.degree. C. for about 6 
to about 16 hours, then in air at about 400.degree. to about 1000.degree. 
C. for about 3 to about 8 hours, and then optionally with steam at about 
250.degree. to about 700.degree. C. for about 0.5 to about 36 hours. 
This invention according to a third aspect provides a process for carrying 
out chemical reactions using a ferrisilicate molecular sieve of the ZSM-5 
type as described above. According to this process, a gaseous reactant or 
mixture thereof is contacted with the ferrisilicate molecular sieve under 
reaction conditions. In particular, this process may be a catalytic 
process in which a mixture of carbon monoxide and hydrogen is contacted 
with the molecular sieve at a temperature from about 250.degree. to about 
400.degree. C. and at a pressure from about one to about 20 atmospheres, 
whereby a reaction produce comprising a hydrocarbon or mixture thereof is 
obtained. This hydrocarbon or mixture thereof comprises a major portion of 
gasoline range (C.sub.6 to C.sub.10) hydrocarbons when the temperature is 
maintained from about 250.degree. to about 350.degree. C. and the pressure 
is from about 10 to about 20 atmospheres. 
BEST MODE FOR CARRYING OUT THE INVENTION 
The ferrisilicate molecular sieves of the present invention have an overall 
SiO.sub.2 /Fe.sub.2 O.sub.3 mole ratio in the range of about 20 to about 
400, preferably from about 30 to about 200, and exhibit ZSM-5 structure. 
These molecular sieves consist structurally of a three-dimensional 
framework of SiO.sub.4.sup.- and FeO.sub.2.sup.- tetrahedra which are 
interlinked by common oxygen atoms. 
Only a portion of the iron content of final product (i.e., thermally 
treated) molecular sieves of this invention is in the framework. Framework 
iron is in the form of tetrahedra. Framework iron may constitute as little 
as 20 percent (by weight) of total iron; typically however, framework iron 
is from about 50 to 100 percent of the total iron content. The remainder 
of the iron is outside of the framework in the form of octahedra, and 
consists essentially of finely divided particles of iron oxides dispersed 
on the internal and external surfaces of the molecular sieve. Nearly all 
of the particles on the internal surfaces are smaller than about 5 
Angstroms (A) in size. Particles on the external surfaces are 
predominantly from 5 to 15 .ANG.. Most of the non-framework iron is 
dispersed on the internal surfaces, i.e. surfaces of the pores and the 
cavities (which for convenience will simply be referred to as the pore 
surfaces) of the sieve. The thermally treated molecular sieves may range 
from off white to brown in color. Distribution of the iron content of the 
molecular sieve between the framework and non-framework sites may be shown 
by Mossbauer spectra. Thermally treated molecular sieves of this invention 
have a high degree of thermal stability. 
The electronegativity of framework iron is balanced by exchangeable 
cations, e.g. hydrogen, ammonium, alkali metal or alkaline earth metal, in 
the crystal structure. The ion exchange capacity of a product molecular 
sieve furnishes a quantitative measure of the amount of framework 
(tetrahedral) iron present. Thermally treated molecular sieves as produced 
are in the hydrogen form; other exchangeable cations may be introduced by 
conventional ion exchange techniques. The overall SiO.sub.2 /Fe.sub.2 
O.sub.3 mole ratio of a thermally treated molecular sieve herein is based 
on the total quantity (framework plus non-framework) iron present. 
The ferrisilicate molecular sieves of this invention exhibit ZSM-5 
structure and may be regarded as analogs of the known crystalline 
aluminosilicate zeolite molecular sieves. Such molecular sieves are 
described, for example, in U.S. Pat. No. 3,702,886 cited above. One 
indication of ZSM-5 structure is the presence of pores of a uniform 
diameter of about 5.5 Angstroms. Another indication is an x-ray 
diffraction pattern which is similar to that of known ZSM-5 molecular 
sieves. The x-ray diffraction pattern of the molecular sieves of this 
invention is shown in Table I below. 
TABLE I 
______________________________________ 
Inten- 
Number 2, Theta sity I/Io 
______________________________________ 
1 7.78 689 28 
2 8.72 520 21 
3 11.68 153 6 
4 13.66 156 6 
5 13.84 226 9 
6 15.78 192 7 
7 17.6 116 4 
8 19.14 162 6 
9 20.22 252 9 
10 22.06 173 7 
11 22.96 2144 88 
12 23.14 2431 100 
13 23.58 676 27 
14 23.82 1105 45 
15 24.28 780 32 
16 25.64 130 5 
17 26.5 180 7 
18 26.84 240 9 
19 29.14 212 8 
20 29.78 236 9 
______________________________________ 
As synthesized ferrisilicate molecular sieves of this invention are 
crystals having a white to pale lemon yellow color, indicating that all or 
most (e.g., at least 90 percent) of the iron content is in the framework, 
and having the same mole ratio of silica to ferric oxide (i.e. from about 
20 to about 400) that characterizes the final product. The percentage of 
iron in the framework is lower at SiO.sub.2 /Fe.sub.2 O.sub.3 mole ratios 
below about 50. The as synthesized ferrisilicate molecular sieves may be 
represented on the water free basis by the following formula: 
EQU aR.sub.2 O.multidot.Fe.sub.2 O.sub.3 .multidot.bSiO.sub.2 
where R is alkylammonium, dialkylammonium, trialkyl-ammonium or 
tetraalkylammonium; a is from about 1 to about 6; and b is from about 20 
to about 400. R is preferably tetraalkylammonium, and the alkyl groups are 
lower alkyl groups, i.e., alkyl groups containing from one to about 8 
carbon atoms. A minor amount of R may be accounted for by an alkali metal 
ion, e.g. sodium. 
The x-ray diffraction pattern of the as synthesized molecular sieve is 
substantially the same as that of the final product molecular sieve, i.e., 
as shown in Table I. 
Preparation of the product ferrisilicate molecular sieves of this invention 
requires two operations, i.e. (1) preparation of the as synthesized 
ferrisilicate, and (2) thermal treatment of the as synthesized 
ferrisilicate i order to form the product ferrisilicate molecular sieve. 
The as synthesized ferrisilicate is preferably formed by adding a silica 
source to an acidic solution of an iron (III) (i.e., ferric compound, 
adding to the resulting gel a primary amine, a secondary amine, and 
tertiary amine, or a quaternary ammonium salt and heating the resulting 
mixture (which is a gel), preferably in an autoclave under autogenous 
conditions at about 100.degree. to about 250.degree. C., until 
crystallization takes place. 
The acidified solution of a ferric [i.e., ions (III)] compound is obtained 
by dissolving an iron (III) compound, such as ferric nitrate, ferric 
chloride or ferric sulfate, in water and acidifying the resulting solution 
with a strong mineral acid such as hydrochloric or sulfuric acid to pH not 
higher than about 5. 
The silica source (or precursor) may be either an aqueous solution of an 
alkaline metal silicate or an aqueous silica sol. Alkali metal silicate 
solutions are ordinarily preferred, because these result in better 
incorporation of the iron into the framework, while use of a silica sol 
results in a substantial amount of non-framework (octahedral) iron in the 
as synthesized ferrisilicate. Representative alkaline metal silicates are 
N-Brand silicate (PQ Corporation), which has the formula Na.sub.2 
SiO.sub.3.5H.sub.2 O. Sodium metasilicate from other vendors can also be 
used. Other sodium silicates having different SiO.sub.2 /Na.sub.2 O mole 
ratios may also be used. Representative silica sols (less suitable as 
previously indicated) include "LUDOX" (E. I. Dupont Company) and 
"Cab-O-Sil" (Cabot Corp.), both of which contain particles of high 
molecular weight polymeric silica beads. 
It is important to add the silica source to the iron (III) solution, rather 
than to add the iron solution to the silica source or to charge both 
simultaneously to a reaction vessel, because it is important to maintain 
an acidic pH, preferably below about 5 throughout the addition of the 
silica source. If this is not done, iron (III) hydroxide will precipitate 
and the desired incorporation of substantially all of the iron into the 
framework of the as synthesized ferrisilicate gel, and the desired 
distribution and particle size characteristics of the iron in the final 
product molecular sieve, will not be obtained. 
The amine or quaternary ammonium salt is preferably added after the 
addition of the silica source is complete. The amines are primary, 
secondary or tertiary alkyl amines in which the alkyl group contains from 
1 to about 8 carbon atoms. Tertiary amines are preferable to the primary 
or secondary amines. A representative tertiary amine is tripropylamine. 
Preferred, however, are the quaternary ammonium salts, which are 
tetraalkyl ammonium salts of strong acids, the alkyl group containing from 
about 1 to about 8 carbon atoms. A representative quaternary ammonium salt 
is tetrapropylammonium (TPA) bromide. 
A minor amount of alkali metal (e.g., sodium) salt may be used in addition 
to the amine or quaternary ammonium salt, but the latter must constitute 
the major source of exchangeable ions in the molecular sieve as 
synthesized. 
The amine or quaternary ammonium salt and the silica source may be added 
simultaneously to the acidified iron (III) solution is desired, provided 
that the pH of the solution is maintained in the acidic state and 
preferably at a pH not over about 5 until addition of most of the silica 
source is complete. (When simultaneous addition is used, addition of the 
silica source may be completed before addition of the amine or quaternary 
ammonium salt is completed). However, it is ordinarily preferred to add 
the amine or quaternary ammonium salt after all of the silica source has 
been added. 
The mole ratios of quaternary ammonium compound, iron compound and silica 
source expressed as R.sub.2 O, Fe.sub.2 O.sub.3 and SiO.sub.2 
respectively, in the reactants are substantially the same as the ratio in 
the as synthesized ferrisilicate gel. 
Ferrisilicate gel is placed in an autoclave and heated under autogenous 
pressure at about 100.degree. to about 250.degree. C. (preferably about 
170.degree. C.) for 2 to 5 days. The resulting white solid may be 
separated from the mother liquor, e.g., by filtration or centrifugation, 
then washed with water and dried at about 100.degree. C. The resulting 
material is an as synthesized highly crystalline ferrisilicate molecular 
sieve. X-ray powder diffraction confirms the formation of the ZSM-5 
structure. 
The as synthesized molecular sieve is thermally treated. This generally 
causes a portion of the iron to migrate from the framework to the internal 
surfaces (and to a slight degree to the external surfaces as well). 
Thermal treatment comprises treatment with nitrogen, air and/or steam at a 
temperature from about 250.degree. C. to about 1000.degree. C. Preferred 
thermal treatment according to this invention includes treatment in an 
inert atmosphere, preferably a flowing stream of nitrogen, at a 
temperature from about 450.degree. to about 800.degree. C. for about 6 to 
about 16 hours, followed by calcining in air at a temperature from about 
400.degree. to about 1000.degree. C. for about 3 to about 8 hours. The 
extent for iron migration depends on the treating agent or agents used 
(steam causing the greatest migration), and the temperature and time of 
treatment. Thermal treatment causes decomposition of the organic material 
(amine or quaternary ammonium salt). At least a portion of the thermal 
treatment should be with air in order to assure complete decomposition. 
After calcination with nitrogen and air, or with air alone, the 
ferrisilicate molecular sieve is ammonium ion exchanged, in order to 
remove any sodium ion present. This may be done with an aqueous solution 
of an ammonium salt of strong mineral acid, such as ammonium nitrate. 
After ammonium ion exchange, the molecular sieve is again thermally 
treated, either by calcination in air or by hydrothermal treatment with 
steam. According to one mode of treatment, the molecular sieve may be air 
dried at about 100.degree.-120.degree. C., then heated at a somewhat 
higher temperature, (e.g. about 250.degree. to about 350.degree. C.) for 
about 2 to 6 hours, and then calcined at high temperature, (e.g. about 
550.degree. to about 650.degree. C.) for a longer time, (e.g. 6 to 24 
hours). Finally, the calcined material may be ion exchanged, for example 
with potassium ion (as dilute KOH to a pH of 8.0), washed with water, 
filtered and air dried at about 100.degree.-120.degree. C. The produce 
molecular sieve formed in this manner typically contains about 50-100 
percent of the iron in the framework, the remainder (about 0 to 50 
percent) being finely dispersed throughout the molecular sieve, including 
the pore surfaces. Only a small amount of the non-framework iron is on the 
outside surfaces, which is desirable because iron on the outside surfaces 
is less reactive for catalytic reaction purposes. The non-framework iron 
is in the form of particles of iron oxides; nearly all the particles on 
internal surfaces are smaller than 0.5 .ANG. while those on external 
surfaces are predominantly from 5 .ANG. to 15 .ANG.. 
The ammonium exchanged molecular sieve described above may be 
hydrothermally treated with steam at about 300.degree. to about 
700.degree. C. for about 1 to 4 hours, washed with water, filtered and air 
dried at about 100.degree. to 120.degree. C. Hydrothermal treatment with 
steam causes a much larger portion of the framework iron to migrate 
outside the framework and to become dispersed as finely divided iron oxide 
particles on the pore surfaces. Hydrothermal treatment with steam also 
causes a greater percentage of the non-framework iron to migrate to the 
external surfaces than is the case when a molecular sieve is thermally 
treated with nitrogen and air only, or with air alone. For example, a 
molecular sieve treated with steam at 550.degree. to 650.degree. C. for 1 
to 4 hours may contain about 15 to 40 percent of the iron in the 
framework, and conversely about 60 to about 85 percent of the iron outside 
the framework, principally in the form of finely divided iron oxide 
particles not larger than about 5 Angstroms dispersed mainly on the 
internal surfaces. Typically about 95-97 percent of total non-framework 
iron in thermally treated molecular sieves (less in those having SiO.sub.2 
/Fe.sub.2 O.sub.3 mole ratio less than 50) is on the internal surfaces. 
The ion exchange capacity of final product molecular sieves may be 
determined by ion exchange with dilute KOH to pH 8.0 prior to final 
washing and drying if desired. 
The unit cell diameter of molecular sieves of this invention ranges from 
about 5330 .ANG. (at a SiO.sub.2 /Fe.sub.2 O.sub.3 mole ratio of 100) to 
about 5410 .ANG. (at a SiO.sub.2 /Fe.sub.2 O.sub.3 mole ratio of 20). 
Little further change in the unit cell diameter takes place as the 
SiO.sub.2 /Fe.sub.2 O.sub.3 ratio is increased above 100. 
When molecular sieves according to this invention are used for catalytic 
purposes, the materials should generally be available in the form of 
particles with a diameter of about 0.5 to about 5 millimeters. Typically 
the final product molecular sieve have a particle diameter in the range of 
about 0.5 to about 8 microns. To achieve larger size, and in increase 
thermal stability, the molecular sieve may be composited with an inorganic 
matrix or binder material if desired. Examples of suitable matrix or 
binder materials are naturally occurring clays, such as kaolin and 
bentonite. Other suitable matrix or binder materials are synthetic 
inorganic oxide, such as alumina, silica, zirconia or combinations 
thereof, as for example silica-alumina and silica-zirconia. The ratio of 
molecular sieve to matrix material may be as desired, and typically 
molecular sieve constitutes from about 10 to about 100 percent by weight 
of a composite. 
Molecular sieves according to this invention may be used as catalysts in 
various reactions, but are particularly suitable as Fischer-Tropsch 
catalysts for the direct conversion of mixtures of carbon monoxide and 
hydrogen to hydrocarbons, without forming and recovering methanol as an 
intermediate. The carbon monoxide-hydrogen mixture may be derived by 
conventional means, as for example steaming of coal. The mole ratio of CO 
to H.sub.2 in the reactant mixture may range from about 1:1 to about 3:1. 
Such a reactant mixture is contacted with a molecular sieve of this 
invention under reaction conditions, e.g. a pressure ranging from about 
atmospheric to about 20 atmospheres, a temperature ranging from about 
250.degree. to about 400.degree. C., and at a weight hourly space velocity 
from about 0.1 to about 100 reciprocal hours (h.sup.-1). The reaction 
product is a hydrocarbon mixture. The reaction mixture formed includes 
both the reaction product and unreacted carbon monoxide and hydrogen. The 
term "reaction produce", in this specification is used to denote only 
those materials produced in the chemical reaction, while "reaction 
mixture" denotes the mixture of reaction product and unreacted starting 
materials obtained). 
Ferrisilicate molecular sieves of this invention may also be used for other 
catalytic reactions, particularly iron oxide-catalyzed catalytic 
reactions. In particular, the molecular sieves of this invention may be 
used as dehydrogenation and oxidation catalysts, e.g. in the oxidation of 
butene to butadiene, oxidation of olefins to alkene acetate esters, 
dehydrogenation of ethylbenzene to styrene, and oxydehydrogenation of 
isobutyric acid to methyacrylic acid or a lower alkyl ester thereof. Other 
reactions include decomposition of 2-butanol. Catalysts of this invention 
can also be used by hydrogenation catalysts for liquification of coal. 
A major advantage of the molecular sieves of this invention is their 
ability to catalyze direct formation of hydrocarbons, particularly 
gasoline hydrocarbons from carbon monoxide-hydrogen mixtures without the 
necessity of producing and recovering methanol as an intermediate. 
Furthermore, the catalysts of this invention have good selectivity for 
this reaction, which is believed due to the dispersion of iron oxides on 
the internal surfaces (i.e. the pores) of the molecular sieve with only a 
comparatively small amount of iron oxides on the external surface. (Iron 
oxides dispersed on external surfaces tend to catalyze reactions 
non-selectively, while iron oxides dispersed on internal surfaces promote 
selective reactions). Molecular sieves of this invention are also 
selective catalysts for other iron oxide-catalyzed reactions. 
Molecular sieves of this invention are also useful as isomerization and 
cracking catalysts. For example, they may be used for isomerization of 
straight chain alkanes to branch chain alkanes, e.g. n-hexane to 
isohexane. They are also useful as cracking catalysts for cracking heavy 
hydrocarbon fractions to produce gasoline range hydrocarbons. The 
preferred molecular sieves for isomerization and cracking are those in 
which a major portion, e.g. from about 50 to about 100 percent of total 
iron, remains in the framework after thermal treatment. 
This invention will be further described with reference to the examples 
which follow. The SiO.sub.2 /Fe.sub.2 O.sub.3 ratio given in each example 
refers to overall mole ratio. 
Samples of both as synthesized and thermally treated molecular sieves were 
analyzed according to the procedures indicated below. 
The x-ray powder defraction data were obtained using a Phillips X-Ray 
Difractometer (Ni filtered Cu K-alpha, 2-theta range 
5.degree.-40.degree.). For comparison, known samples of the 
aluminosilicate ZSM-5 were used. Chemical analysis of the samples was done 
by atomic absorption spectroscopy. SEM analysis was conducted using a 
Cambridge Scanning Electron Microscope with Trace Northern X-ray detector. 
Mossbauer spectra were measured using a conventional constant acceleration 
spectrometer, using a source of .sup.57 CoinRh. Spectra were recorded in 0 
field at room temperature (RT) or liquid nitrogen temperature (LNT; 
77.degree. K.) and at 4.2.degree. K. with either a low magnetic field 
(0.05 T) or a high field (8 T) applied parallel to the gamma ray 
direction. All isometer shifts are quoted relative to an absorber of 
metallic iron at room temperature. Fits at low field were performed using 
a standard lease square fitting routine. When fitting quadruple doublets, 
both peaks were constrained to have the same line with and intensity. 
Hyperfine split sextats were fit to 3 doublets and the hyperfine field 
estimated splitting of the outermost line. In all cases, it was found that 
the quadropole splitting (magnetic) was negative 0 mms/second. Average 
isomer shifts were calculated directly from the raw data by summation or 
from the fits. High field fits of paramagnetic spectra were obtained using 
a spin Hamiltonian simulation program. 
Mossbauer spectral analysis disclose: the distribution between framework 
and non-framework iron, and the approximate particle size of the latter. 
Framework iron is in the form of tetrahedra, which in the Mossbauer 
spectra are indicated by a singlet or single peak (when absorption is 
measured against velocity in mm/sec) regardless of measurement 
temperature, with an average isomer shift (IS) no more than 0.3 mm/sec at 
room temperature. A doublet in the Mossbauer spectrum indicates a mixture 
of tetrahedral and octahedral iron, with the latter dispersed in a fine 
state of subdivision (no larger than 0.6 nanometers). A sexlet or six-line 
spectrum indicates the presence of large agglomerates (larger than 0.6 
nanometers) of iron oxides. The Mossbauer spectrum indicates the presence 
of all iron present, regardless of its location. 
Color of all samples was observed. All as synthesized samples were white, 
indicating that all or nearly all of the iron is in the framework at this 
stage. Thermally treated samples range from off-white to brown in color. 
Any discoloration indicates that at least part of the iron is present 
outside the framework as iron oxides. Color furnishes a qualitative 
indication as to the presence or absence of non-framework iron. 
All thermally treated samples were base exchanged with the dilute potassium 
hydroxide to pH 8.0 in order to obtain base exchange capacity. Both the 
acidity and the base exchange capacity diminish as the amount of framework 
iron decreases. Therefore, observed base exchange capacity furnishes a 
confirmation of the amount of framework iron as determined by atomic 
absorption spectroscopy.

EXAMPLE 1 
As-synthesized ferrisilicate molecular sieve. SiO.sub.2 Fe.sub.2 O.sub.3 
=98 
100 g N-brand Silica (PQ Corp., Valley Forge, PA, Na.sub.2 
SiO.sub.3.5H.sub.2 O) in 100 g H.sub.2 O, is added to a solution 
containing 4.16 g Fe(NO.sub.3).sub.3.9H.sub.2 O dissolved in 50 g H.sub.2 
O. The pH is adjusted to be strongly acidic with 7.5 g H.sub.2 SO.sub.4 
(96 percent). To the resulting pale lemon colored gel is added 12 g 
tetrapropylammonium bromide (Aldrich Chemical) in 50 g H.sub.2 O. After 
vigorous agitation the mixture is placed in a stainless steel autoclave, 
sealed and heated under its own pressure at 170.degree. C. for 2 to 5 
days, without stirring. The resulting white solid is filtered, washed with 
water and dried at 100.degree. C. X-ray powder diffraction confirms the 
formation of the ZSM-5 structure. The material contains almost all of its 
iron in the framework of the molecular sieve, as shown by Mossbauer 
spectroscopy. 
EXAMPLE 2 
Thermally modified ferrisilicate molecular sieve, SiO.sub.2 /Fe.sub. 2 
O.sub.3 =98 
The sample from Example 1 is heated in air at 110.degree. C. for three 
hours. It is then carefully calcined in dry air in two stages. In the 
first stage it is heated in dry air at 300.degree. C. for 2-3 hours 
followed by a second stage, where it is calcined in dry air at 600.degree. 
C. for 18 hours. The sample obtained was then ammonium exchanged using 
excess 1M ammonium nitrate solution at 65.degree. C. for two hours. The 
resulting solid sample is named as sample A for future reference herein. A 
portion of the sample A is heated at 110.degree. C. for two hours. It is 
then heated in dry air at 300.degree. C. for three hours and calcined in 
dry air at 600.degree. C. for 18 hours. The sample is then potassium 
exchanged by titrating it with dilute KOH to a pH of 8.0. The sample is 
finally washed with water, filtered and air dried at 110.degree. C. This 
material contains 71 percent of the iron in the framework of the molecular 
sieve. The remaining 29 percent of the iron is very finely dispersed 
throughout the molecular sieve, including the inside of the pores. 
EXAMPLE 3 
Hydrothermally modified ferrisilicate molecular sieve under mild 
conditions, SiO.sub.2 /Fe.sub.2 O.sub.3 =98 
A portion of the sample A (of Example 2) is hydrothermally treated using 
steam at 650.degree. C. for one hour. The sample is then potassium 
exchanged by titrating it with dilute KOH to a pH of 8.0. The resulting 
sample is washed with water, filtered and air dried at 110.degree. C. This 
material contains 35 percent of the iron in the framework of the molecular 
sieve. The remaining 60 percent of the iron is outside the framework and 
is present inside and outside the pores of the molecular sieve. 
EXAMPLE 4 
Hydrothermally modified ferrisilicate molecular sieve under severe 
conditions. SiO.sub.2 /Fe.sub.2 O.sub.3 =98 
A portion of the sample A (of Example 2) is hydrothermally treated using 
steam at 600.degree. C. for 4 hours. The sample is then potassium 
exchanged by titrating it with dilute KOH to a pH of 8.0. The resulting 
sample is washed with water, filtered and air dried at 110.degree. C. This 
material contains only 20 percent of the total iron in the framework of 
the molecular sieve. The remaining 80 percent of the iron is outside the 
framework and is present inside and outside the pores of the molecular 
sieves. 
EXAMPLE 5 
As synthesized molecular sieves; SiO.sub.2 /Fe.sub.2 O.sub.3 ranging from 
20 to 200 (General Procedure) 
The iron containing reagent (Fe(NO.sub.3).sub.3. 9H.sub.2 O, or 
FeCl.sub.3.H.sub.2 O) Fisher Reagent Grade) was dissolved in 100 g H.sub.2 
O. The solution, was acidified with 16 g H.sub.2 SO.sub.4 (96 percent) and 
200 g N-brand silica (PQ Corp. Na.sub.2 SiO.sub.3.5H.sub.2 O) in 200 g 
H.sub.2 O was added to this fresh solution. Immediate formation of a pale 
yellow gel was observed. To the gel was added 24 g tetrapropylammonium 
bromide (TPABr Aldrich Reagent Grade) in 40 g H.sub.2 O. The gel was 
heated in a stirred autoclave (Autoclave Engineers 1 dm.sup.3 capacity) at 
170.degree. C. for 3 days under autogeneous pressure. The resulting white 
solid was filtered, washed and dried at 100.degree. C. X-ray powder 
diffraction confirmed the presence of highly crystalline ferrisilicate 
with the zeolite ZSM-5 structure. Atomic absorption confirms S10.sub.2 
/Fe.sub.2 O.sub.3 ratio. 
FeZSM-5 (20): To 3.4 g, FeCl.sub.3.H.sub.2 O in 50 g H.sub.2 O with 4.5 g 
H.sub.2 SO.sub.4 is added 50 g N-brand silica in 50 g H.sub.2 O. to the 
resulting gel was added 6.3 g TPABr in 10 H.sub.2 O. 
FeZSM-5 (50): To 15 g Fe(NO.sub.3).sub.3.9H.sub.2 O in 100 g H.sub.2 O and 
16 g H.sub.2 SO.sub.4 was added 200 g N-brank silica in 200 g H.sub.2 O. 
After precipitates of the gel, 24 g TPABr in 40 g H.sub.2 O was added. 
FeZSM-5 (90): To 4.16 g Fe (NO.sub.3).sub.3.9H.sub.2 O dissolved in 50 g 
H.sub.2 O and acidified with 7.5 g H.sub.2 SO.sub.4 was added 100 g 
N-brank silicate in 100 g H.sub.2 O. After formation of the milky gel, 12 
g TPABr in 25 g H.sub.2 O was added. 
FeZSM-5 (171): to 3.5 g Fe(NO.sub.3).sub.3.9H.sub.2 O dissolved in 100 g 
H.sub.2 O and 16 g H.sub.2 O.sub.4 was added 200 g N-brand silica in 200 g 
H.sub.2 O. After the white milly gel formed, 24 g TPABr in 50 g H.sub.2 O 
was added. 
Silicalite: To a 15 g H.sub.2 SO.sub.4 in 75 g H.sub.2 O solution was added 
150 g N-brank silicate in 150 g H.sub.2 O to this was added 18 g TPA Br in 
100 g H.sub.2 O. (This is included for comparison). 
EXAMPLE 6 
Thermally modified ferrisilicate molecular sieve; SiO.sub.2 /Fe.sub.2 
O.sub.3 =20 
The as-synthesized sample of ferrisilicate molecular sieve with SiO.sub.2 
/Fe.sub.2 O.sub.3 of 20 is dried in air at 110.degree. C. for three hours. 
It is then heated in dry nitrogen for two hours at 145.degree. C., 
followed by heating at 500.degree. C. for 8-10 hours. It is cooled to 
145.degree. C. in dry nitrogen and then switched to dry air at 145.degree. 
C. for 2 hours. Finally, the sample is calcined in dry air at 500.degree. 
C. for 4 to 5 hours. 
An ammonium exchanged form of the sample was obtained by ammonium exchange 
using excess 1M ammonium nitrate solution at 65.degree. C. for two hours. 
A portion of this sample is heated at 110.degree. C. for two hours, then 
heated in dry air at 145.degree. C. for two hours and finally calcined in 
dry air at 500.degree. C. for 5 hours. The sample is then potassium 
exchanged by titrating it with dilute KOH to a pH of 8.0. 
EXAMPLE 7 
Hydrothermally modified ferrisilicate molecular sieve under very mold 
conditions SiO.sub.2 /Fe.sub.2 O.sub.3 =20 
A portion of the ammonium exchanged sample (of Example 6) is hydrothermally 
treated using steam at 300.degree. C. for one to four hours. The sample is 
then potassium exchanged by titrating it with dilute KOH to a pH of 8.0. 
The resulting sample is washed with water, filtered and air dried at 
110.degree. C. 
EXAMPLE 8 
Hydrothermally modified ferrisilicate molecular sieve under mild 
conditions. SiO.sub.2 /Fe.sub.2 O.sub.3 =20 
A portion of the ammonium exchanged sample (of Example 6) is hydrothermally 
treated using steam at 550.degree. C. for one hour. The sample is then 
potassium exchanged by titrating it with dilute KOH to a pH of 8.0. The 
resulting sample is washed with water, filtered and air dried at 
110.degree. C. 
EXAMPLE 9 
Hydrothermally modified ferrisilicate molecular sieve under moderate 
conditions; SiO.sub.2 /F.sub.2 O.sub.3 =20 
Two portions of the ammonium exchanged samples (of Example 6) 
hydrothermally treated using steam at 550.degree. C. for two and four 
hours respectively. The two portions are then potassium exchanged 
separately by titrating them with dilute KOH to a pH of 8.0. The resulting 
samples are washed with water, filtered and air dried at 110.degree. C. 
EXAMPLE 10 
Hydrothermally modified ferrisilicate molecular sieves under moderate 
conditions for long periods of time; SiO.sub.2 /Fe.sub.2 O.sub.3 =20 
Portions of the ammonium exchanged samples of Example 6 are hydrothermally 
treated using steam at 550.degree. C. for 8 to 72 hours. The samples are 
then potassium exchanged by titrating them separately with dilute KOH to a 
pH of 8.0. The resulting samples are washed with water, filtered and air 
dried at 110.degree. C. 
EXAMPLE 11 
Hydrothermally modified ferrisilicate molecular sieves under severe 
conditions; SiO.sub.2 /Fe.sub.2 O.sub.3 =20 
Portions of the ammonium exchanged samples of Example 6 are hydrothermally 
treated using steam at 600.degree. to 700.degree. C. for one to 8 hours. 
The samples are then potassium exchanged by titrating them separately with 
dilute KOH to a pH of 8.0. The resulting samples are washed with water, 
filtered and air dried at 110.degree. C. 
EXAMPLE 12 
Thermally modified ferrisilicate molecular sieve; SiO.sub.2 /Fe.sub.2 
O.sub.3 =50 
The as synthesized sample of ferrisilicate molecular sieve with SiO.sub.2 
/Fe.sub.2 O.sub.3 of 50 is heated in air at 110.degree. C. for three 
hours. It is then heated in dry nitrogen for two hours at 145.degree. C. 
followed by heating at 500.degree. C. in dry nitrogen for 8-10 hours. It 
is cooled to 145.degree. C. in dry nitrogen and then switched to dry air 
at 145.degree. C. for 2 hours. Finally, the sample is calcined in dry air 
at 500.degree. C. for 4 to 5 hours. 
An ammonium exchanged form of the sample was obtained by ammonium exchange 
using excess 1M ammonium nitrate solution at 65.degree. C. for two hours. 
For hydrothermal modification of the material, an ammonium exchanged form 
of the sample is obtained by ammonium exchanged using excess 1M ammonium 
nitrate solution at 65.degree. C. for two hours. 
A portion of this sample is heated at 110.degree. C. for two hours, then 
heated in dry air at 145.degree. C. for two hours and finally calcined in 
dry air at 500.degree. C. for 5 hours. The sample is then potassium 
exchanged by titrating it with dilute KOH to a pH of 8.0. 
EXAMPLE 13 
Hydrothermally modified ferrisilicate molecular sieve under very mild 
conditions; SiO.sub.2 /Fe.sub.2 O.sub.3 =50 
A portion of the ammonium exchanged sample of Example 12 is hydrothermally 
treated using steam at 300.degree. C. for one to four hours. The sample is 
then potassium exchanged by titrating it with dilute KOH to a pH of 8.0. 
The resulting sample is washed with water, filtered and air dried at 
110.degree. C. 
EXAMPLE 14 
Hydrothermally modified ferrisilicate molecular sieve under mild 
conditions; SiO.sub.2 /Fe.sub.2 O.sub.3 =50 
A portion of the ammonium exchanged sample of Example 12 is hydrothermally 
treated using steam at 550.degree. C. for one hour. The sample is then 
potassium exchanged by titrating it with dilute KOH to a pH of 8.0. The 
resulting sample is washed with water, filtered and air dried at 
110.degree. C. 
EXAMPLE 15 
Hydrothermally modified ferrisilicate molecular sieve under moderate 
conditions; SiO.sub.2 /Fe.sub.2 O.sub.3 =50 
Two portions of the ammonium exchanged sample of Example 12 is 
hydrothermally treated using steam at 550.degree. C. for two and four 
hours respectively. The two portions are potassium exchanged separately by 
titrating them with dilute KOH to a pH of 8.0. The resulting samples are 
washed with water, filtered and air dried at 110.degree. C. 
EXAMPLE 16 
Hydrothermally modified ferrisilicate molecular sieves under moderate 
conditions for long periods of time; SiO.sub.2 /Fe.sub.2 O.sub.3 =50 
Portions of the ammonium exchanged samples of Example 12 are hydrothermally 
treated using steam at 550.degree. C. for 8 to 72 hours. The samples are 
then potassium exchanged by titrating them separately with dilute KOH to a 
pH of 8.0. The resulting samples are washed with water, filtered and air 
dried at 110.degree. C. 
EXAMPLE 17 
Hydrothermally modified ferrisilicate molecular sieves under severe 
conditions; SiO.sub.2 /Fe.sub.2 O.sub.3 =50 
Portions of the ammonium exchanged samples of Example 12 are hydrothermally 
treated using steam at 600.degree. to 700.degree. C. for one to 8 hours. 
The samples are then potassium exchanged by titrating them separately with 
dilute KOH to a pH of 8.0. The resulting samples are washed with water, 
filtered and air dried at 110.degree. C. 
EXAMPLE 18 
Thermally modified ferrisilicate molecular sieve; SiO.sub.2 /Fe.sub.2 
O.sub.3 =90 
The as-synthesized sample of ferrisilicate molecular sieve with SiO.sub.2 
/Fe.sub.2 O.sub.3 of 90 is heated in air at 110.degree. C. for three 
hours. It is then heated in dry nitrogen for two hours at 145.degree. C. 
followed by heating it at 500.degree. C. in dry nitrogen for 8-10 hours. 
It is cooled to 145.degree. C. in dry nitrogen and then switched to dry 
air at 145.degree. C. for 2 hours. Finally, the sample is calcined in dry 
air at 500.degree. C. for 4 to 5 hours. 
For hydrothermal modification of the material, an ammonium exchanged form 
of the sample is obtained by ammonium exchange using excess 1M ammonium 
nitrate solution at 65.degree. C. for two hours. 
A portion of this sample is heated at 110.degree. C. for two hours, then 
heated in dry air at 145.degree. C. for two hours and finally calcined in 
dry air at 500.degree. C. for 5 hours. The sample is then potassium 
exchanged by titrating it with dilute KOH to a pH of 8.0. 
EXAMPLE 19 
Hydrothermally modified ferrisilicate molecular sieve under very mild 
conditions; SiO.sub.2 /Fe.sub.2 O.sub.3 =90 
A portion of the ammonium exchanged sample of Example 18 is hydrothermally 
treated using steam at 300.degree. C. for one to four hours. The sample is 
then potassium exchanged by titrating it with dilute KOH to a pH of 8.0. 
The resulting sample is washed with water, filtered and air dried at 
110.degree. C. 
EXAMPLE 20 
Hydrothermally modified ferrisilicate molecular sieve under mild 
conditions. SiO.sub.2 /Fe.sub.2 O.sub.3 
A portion of the ammonium exchanged sample of Example 18 is hydrothermally 
treated using steam at 550.degree. C. for one hour. The sample is then 
potassium exchanged by titrating it with dilute KOH to a pH of 8.0. The 
resulting sample is washed with water, filtered and air dried at 
110.degree. C. 
EXAMPLE 21 
Hydrothermally modified ferrisilicate molecular sieve under moderate 
conditions; SiO.sub.2 /Fe.sub.2 O.sub.3 =90 
Two portions of the ammonium exchanged sample of Example 18 are 
hydrothermally treated using steam at 550.degree. C. for two and four 
respectively. The two portions are potassium exchanged separately by 
titrating them with dilute KOH to a pH of 8.0. The resulting samples are 
washed with water, filtered and air dried at 110.degree. C. 
EXAMPLE 22 
Hydrothermally modified ferrisilicate molecular sieves under moderate 
conditions for long periods of time; SiO.sub.2 /Fe.sub.2 O.sub.3 =90 
Portions of the ammonium exchanges samples of Example 18 are hydrothermally 
treated using steam at 550.degree. C. for 8 to 72 hours. The samples are 
then potassium exchanged by titrating them separately with dilute KOH to a 
pH of 8.0. The resulting samples are washed with water, filtered and air 
dried at 110.degree. C. 
EXAMPLE 23 
Hydrothermally modified ferrisilicate molecular sieves under severe 
conditions SiO.sub.2 /Fe.sub.2 O.sub.3 =90 
Portions of the ammonium exchanged samples of Example 18 are hydrothermally 
treated using steam at 600.degree. to 700.degree. C. of done to 8 hours. 
The samples are then potassium exchanged by titrating them sieve dilute 
KOH to a pH of 8.0. The resulting samples are washed with water, filtered 
and air dried at 110.degree. C. 
EXAMPLE 24 
Thermally modified ferrisilicate molecular sieve; SiO.sub.2 /Fe.sub.2 
O.sub.3 =200 
The as-synthesized sample of ferrisilicate molecular sieve with SiO.sub.2 
/Fe.sub.2 O.sub.3 of 200 is heated in air at 110.degree. C. for three 
hours. It is then heated in dry nitrogen for two hours at 145.degree. C. 
followed by heating it at 500.degree. C. in dry nitrogen for 8 to 10 
hours. It is cooled to 145.degree. C. in dry nitrogen and then switched to 
dry air at 145.degree. C. for 2 hours. Finally, the sample is calcined in 
dry air at 500.degree. C. for 4 to 5 hours. 
For hydrothermal modification of the material, an ammonium exchanged form 
of the sample was obtained by ammonium exchange using excess 1M ammonium 
nitrate solution at 65.degree. C. for two hours. 
A portion of this sample is heated at 110.degree. C. for two hours, then 
heated in dry air at 145.degree. C. for two hours and finally calcined in 
dry air at 500.degree. C for 5 hours. The sample is then potassium 
exchanged by titrating it with dilute KOH to a pH of 8.0. 
EXAMPLE 25 
Hydrothermally modified ferrisilicate molecular sieve under very mild 
conditions; SiO/Fe.sub.2 O.sub.3 =200 
A portion of the ammonium exchanged sample of Example 24 is hydrothermally 
treated using steam at 300.degree. C. for one to four hours. The sample is 
then potassium exchanged by titrating it with dilute KOH to a pH of 8.0. 
The resulting sample is washed with water, filtered and air dried at 
110.degree. C. 
EXAMPLE 26 
Hydrothermally modified ferrisilicate molecular sieve under mild 
conditions; SiO.sub.2 /Fe.sub.2 O.sub.3 =200 
A portion of the ammonium exchanged sample of Example 24 is hydrothermally 
treated using steam at 550.degree. C. for one hour. The sample is then 
potassium exchanged by titrating it with dilute KOH to a pH of 8.0. The 
resulting sample is washed with water, filtered and air dried at 
110.degree. C. 
EXAMPLE 27 
Hydrothermally modified ferrisilicate molecular sieve under moderate 
conditions SiO.sub.2 /Fe.sub.2 O.sub.3 =200 
Two portions of the ammonium exchanged sample of Example 24 are 
hydrothermally treated using steam at 550.degree. C. for two and four 
hours respectively. The two portions are then potassium exchanged, 
separately by titrating them with dilute KOH to a pH of 8.0. The resulting 
samples are washed with water, filtered and air dried at 110.degree. C. 
EXAMPLE 28 
Hydrothermally modified ferrisilicate molecular sieves under moderate 
conditions for long periods of time; SiO.sub.2 /Fe.sub.2 O.sub.3 =200 
Portions of the ammonium exchanged samples of Example 24 are hydrothermally 
treated using steam at 550.degree. C. for 8 to 72 hours. The samples are 
then potassium exchanged by titrating them separately with dilute KOH to a 
pH of 8.0. The resulting samples are washed with water, filtered and air 
dried at 110.degree. C. 
EXAMPLE 29 
Hydrothermally modified ferrisilicate molecular sieves under severe 
conditions; SiO.sub.2 /Fe.sub.2 O.sub.3 =200 
Portions of the ammonium exchanged samples of Example 24 are hydrothermally 
treated using steam at 600.degree. to 700.degree. C. for one to 8 hours. 
The samples are then potassium exchanged by titrating them separately with 
dilute KOH to a pH of 8.0. The resulting samples are washed with water, 
filtered and air dried at 110.degree. C. 
EXAMPLE 30 
Preparation of gasoline range hydrocarbons from synthesis gas 
Mixture of carbon monoxide and hydrogen (synthesis gas) are passed over the 
thermally treated ferrisilicate molecular sieve of Example 12 under the 
following process conditions: H.sub.2 /CO ratio of 1.0 to 3.0, pressure of 
15 to 30 atmospheres, temperature of 300.degree. C. to 400.degree., flow 
rates of 8 to 60 cc/min. The weight of catalyst is approximately 0.4 
grams. The products include gasoline range hydrocarbons. 
EXAMPLE 31 
Preparation of light hydrocarbons from synthesis gas 
A series of experiments was conducted in a plug-flow micro-reactor system 
using a hydrothermally treated (for 2 hours at 500.degree. C.) molecular 
sieve having a SiO.sub.2 /Fe.sub.2 O.sub.3 ratio of 50, prepared according 
to Example 15. The H.sub.2 /CO ratio in these experiments is set at 3. 
Approximately 0.4 gram of catalyst is used in each run. Two series of 
experiments, one at one atmosphere, the other at 12 atmospheres, are 
carried out. Flow rates and other process conditions are varied as shown 
in Table II below. Also shown in Table II are the product distributions 
attained in each run. 
TABLE II 
______________________________________ 
Run 1 2 3 4 5 6 
______________________________________ 
Pressure, atm 
1.0 1.0 1.0 12 12 12 
Reactor temp. .degree.C. 
250 300 350 250 300 350 
Feed gas flow rate, 
60.0 60.0 60.0 25 8 6 
cc/.min 
Product distribution, mole % 
Methane 52 45 45 50 45 47 
Ethane -- 8 8 2 22 20 
Ethylene 25 24 24 12 1 1 
Propane -- -- 2 6 12 14 
Propylene 23 21 19 9 2 1 
C.sub.4 -- -- -- -- 7 8 
C.sub.5 -- -- -- -- 4 4 
C.sub.6 -- -- -- -- 3 2 
C.sub.7 -- -- -- -- 1 1 
C8 -- -- -- -- 1 trace 
______________________________________ 
All percentages of hydrocarbon products in the above Table II are based on 
the amount of CO converted. 
While in accordance with patent statutes, a preferred embodiment and best 
mode has been presented, the scope of the invention is not limited 
thereto, but rather is measured by the scope of the attached claims.