Synthesis of pyridine and 3-alkylpyridine

An improved process is provided for selectively synthesizing pyridine and 3-alkylpyridine in high yield by reacting ammonia and a carbonyl reactant selected from the group consisting of formaldehyde, an aldehyde containing from 2 to 4 carbon atoms, a ketone containing from 3 to 5 carbon atoms, and mixtures thereof under effective conditions in the presence of a catalyst comprising an active form of a synthetic porous crystalline MCM-49 or synthetic porous crystalline material characterized by an X-ray diffraction pattern including interplanar d-spacings at 12.36.+-.0.4, 11.03.+-.0.2, 8.83.+-.0.14, 6.18.+-.0.12, 6.00.+-.0.10, 4.06.+-.0.07, 3.91.+-.0.07, and 3.42.+-.0.06 Angstroms, e.g., MCM-22, and recovering from the resulting reaction mixture a product enriched in pyridine and 3-alkylpyridine.

BACKGROUND OF THE INVENTION 
Field of the Invention 
This invention relates to an improved method for selectively synthesizing 
pyridine and 3-alkylpyridine, e.g., 3-picoline, by reaction of ammonia and 
a carbonyl compound selected from the group consisting of formaldehyde, 
aldehydes containing from 2 to 4 carbon atoms, and ketones containing from 
3 to 5 carbon atoms in the presence of catalyst comprising a synthetic 
porous crystalline material. The improvement of the present invention 
involves increased yield and pyridine and 3-alkylpyridine, e.g., 
3-picoline, product, and is realized by the required use as catalyst of a 
composition comprising a specific synthetic porous crystalline material, 
such as, for example, MCM-49, or one characterized by an X-ray diffraction 
pattern including interplanar d-spacings at 12.36.+-.0.4, 11.03.+-.0.2, 
8.83.+-.0.14, 6.18.+-.0.12, 6.00.+-.0.10, 4.06.+-.0.07, 3.91.+-.0.07, and 
3.42.+-.0.06 Angstroms, e.g., MCM-22. 
Another aspect of this invention involves manufacture of 
3-pyridinecarboxylic acid, i.e., nicotinic acid, by reaction of 3-picoline 
recovered from the product of the above reaction with an oxidative 
reagent, such as, for example, KMnO.sub.4. 
Description of Prior Art 
Reaction of acetaldehyde or certain other low molecular weight aldehydes 
and ammonia either in the absence or presence of methanol and/or 
formaldehyde to yield pyridine and alkyl derivatives thereof has been 
carried out in the presence of amorphous silica-alumina composites 
containing various promoters. See, for example, U.S. Pat. Nos. 2,807,618 
and 3,946,020. The yields of desired products using the latter catalysts 
have been poor. Alkylpyridines have also been synthesized, as reported in 
Advances in Catalysis, 18, 344 (1968), by passing gaseous acetaldehyde and 
ammonia over the crystalline aluminosilicates NaX and H-mordenite. While 
initial conversion utilizing these materials as catalysts was high, 
catalyst deactivation by coking was rapid, providing a commercially 
unattractive system, characterized by poor catalytic stability. 
The next step in the progression of pyridine and alkylpyridine synthesis 
was the discovery that the synthetic crystalline zeolites having an 
intermediate pore size as measured by the Constraint Index of the zeolite 
being between 1 and 12, e.g., ZSM-5, provided commercially useful yields 
and product selectivities. U.S. Pat. No. 4,220,783 was pioneer in this 
discovery, teaching synthesis of pyridine and alkylpyridines by reacting 
ammonia and a carbonyl reactant which is an aldehyde containing 2 to 4 
carbon atoms, a ketone containing 3 to 5 carbon atoms or mixtures of said 
aldehydes and/or ketones under effective conditions in the presence of a 
catalyst comprising a crystalline aluminosilicate zeolite having been ion 
exchanged with cadmium and having a silica to alumina ratio of at least 
about 12 and a Constraint Index within the approximate range of 1 to 12. 
Use of the same crystalline material catalyst component as in U.S. Pat. No. 
4,220,783, i.e., having a Constraint Index of from 1 to 12, e.g., ZSM-5, 
in a fluidized or otherwise movable bed reactor is taught in U.S. Pat. No. 
4,675,410. U.S. Pat. No. 4,866,179 teaches synthesis of pyridine by 
reaction of ammonia and a carbonyl compound, preferably with added 
hydrogen, over catalyst comprising a crystalline aluminosilicate zeolite 
which has been ion exchanged with a Group VIII metal of the Periodic 
Table. The crystalline aluminosilicate zeolite has a silica to alumina 
mole rate of at least 15, preferably 30 to 200, a Constraint Index of from 
4 to 12, e.g., ZSM-5, and the process provides a high and selective yield 
of pyridine. 
U.S. Pat. No. 5,013,843 teaches addition of a third aldehyde or ketone to a 
binary mixture of aldehydes and/or ketones used in preparing mixtures of 
pyridine and alkyl-substituted pyridines in large scale continuous 
processes. In a preferred system, propionaldehyde is added to a binary 
mixture of acetaldehyde and formaldehyde to produce beta-pyridine and 
pyridine. The catalyst for this process is a crystalline aluminosilicate 
zeolite in the acidic form having a Constraint Index of from 1 to 12, 
e.g., ZSM-5. 
Applicants know of no prior art teaching the present improvement in 
selective synthesis of pyridine and 3-alkylpyridine, especially 
3-picoline, over catalyst comprising crystals of the presently required 
zeolite. 
SUMMARY OF THE INVENTION 
In accordance with the present invention, there is provided an improved 
process for selectively synthesizing in high yield pyridine and 
3-alkylpyridine, e.g., 3-picoline, by reacting ammonia and a carbonyl 
compound constituting formaldehyde, an aldehyde of 2 to 4 carbon atoms, or 
a ketone of 3 to 5 carbon atoms in the presence of a catalyst comprising 
an active form of specific synthetic porous crystalline material, such as, 
for example, MCM-49, or one characterized by an X-ray diffraction pattern 
including interplanar d-spacings at 12.36.+-.0.4, 11.03.+-.0.2, 
8.83.+-.0.14, 6.18.+-.0.12, 6.00.+-.0.10, 4.06.+-.0.07, 3.91.+-.0.07, and 
3.42.+-.0.06 Angstroms, e.g., MCM-22. This catalyst has been found to 
afford significant improvement in product yield, and in selectivity for 
the production of pyridine and 3-alkyl derivatives of pyridine over the 
use of the aforenoted prior art catalyst materials. 
Crystalline catalyst component materials useful for the improvement of the 
present invention are described in U.S. Pat. No. 4,992,606, incorporated 
entirely herein by reference. U.S. Pat. No. 5,236,575, incorporated 
entirely herein by reference, describes MCM-49, another synthetic 
crystalline material useful as a catalyst component for the present 
process.

EMBODIMENTS 
In its calcined form, the synthetic porous crystalline material component 
employed in the catalyst composition used in the process of this invention 
may be characterized by an X-ray diffraction pattern including the 
following lines: 
TABLE A 
______________________________________ 
Interplanar d-Spacing(A) 
Relative Intensity, I/I.sub.o .times. 100 
______________________________________ 
12.36 .+-. 0.4 m-vs 
11.03 .+-. 0.2 m-s 
8.83 .+-. 0.14 m-vs 
6.18 .+-. 0.12 m-vs 
6.00 .+-. 0.10 w-m 
4.06 .+-. 0.07 w-s 
3.91 .+-. 0.07 m-vs 
3.42 .+-. 0.06 vs 
______________________________________ 
Alternatively, it may be characterized by an X-ray diffraction pattern in 
its calcined form including the following lines: 
TABLE B 
______________________________________ 
Interplanar d-Spacing(A) 
Relative Intensity, I/I.sub.o .times. 100 
______________________________________ 
30.0 .+-. 2.2 w-m 
22.1 .+-. 1.3 w 
12.36 .+-. 0.4 m-vs 
11.03 .+-. 0.2 m-s 
8.83 .+-. 0.14 m-vs 
6.18 .+-. 0.12 m-vs 
6.00 .+-. 0.10 w-m 
4.06 .+-. 0.07 w-s 
3.91 .+-. 0.07 m-vs 
3.42 .+-. 0.06 vs 
______________________________________ 
More specifically, the calcined form may be characterized by an X-ray 
diffraction pattern including the following lines: 
TABLE C 
______________________________________ 
Interplanar d-Spacing(A) 
Relative Intensity, I/I.sub.o .times. 100 
______________________________________ 
12.36 .+-. 0.4 m-vs 
11.03 .+-. 0.2 m-s 
8.83 .+-. 0.14 m-vs 
6.86 .+-. 0.14 w-m 
6.18 .+-. 0.12 m-vs 
6.00 .+-. 0.10 w-m 
5.54 .+-. 0.10 w-m 
4.92 .+-. 0.09 w 
4.64 .+-. 0.08 w 
4.41 .+-. 0.08 w-m 
4.25 .+-. 0.08 w 
4.10 .+-. 0.07 w-s 
4.06 .+-. 0.07 w-s 
3.91 .+-. 0.07 m-vs 
3.75 .+-. 0.06 w-m 
3.56 .+-. 0.06 w-m 
3.42 .+-. 0.06 vs 
3.30 .+-. 0.05 w-m 
3.20 .+-. 0.05 w-m 
3.14 .+-. 0.05 w-m 
3.07 .+-. 0.05 w 
2.99 .+-. 0.05 w 
2.82 .+-. 0.05 w 
2.78 .+-. 0.05 w 
2.68 .+-. 0.05 w 
2.59 .+-. 0.05 w 
______________________________________ 
Most specifically, it may be characterized in its calcined form by an X-ray 
diffraction pattern including the following lines: 
TABLE D 
______________________________________ 
Interplanar d-Spacing(A) 
Relative Intensity, I/I.sub.o .times. 100 
______________________________________ 
30.0 .+-. 2.2 w-m 
22.1 .+-. 1.3 w 
12.36 .+-. 0.4 m-vs 
11.03 .+-. 0.2 m-s 
8.83 .+-. 0.14 m-vs 
6.86 .+-. 0.14 w-m 
6.18 .+-. 0.12 m-vs 
6.00 .+-. 0.10 w-m 
5.54 .+-. 0.10 w-m 
4.92 .+-. 0.09 w 
4.64 .+-. 0.08 w 
4.41 .+-. 0.08 w-m 
4.25 .+-. 0.08 w 
4.10 .+-. 0.07 w-s 
4.06 .+-. 0.07 w-s 
3.91 .+-. 0.07 m-vs 
3.75 .+-. 0.06 w-m 
3.56 .+-. 0.06 w-m 
3.42 .+-. 0.06 vs 
3.30 .+-. 0.05 w-m 
3.20 .+-. 0.05 w-m 
3.14 .+-. 0.05 w-m 
3.07 .+-. 0.05 w 
2.99 .+-. 0.05 w 
2.82 .+-. 0.05 w 
2.78 .+-. 0.05 w 
2.68 .+-. 0.05 w 
2.59 .+-. 0.05 w 
______________________________________ 
Examples of such porous crystalline materials include the PSH-3 composition 
of U.S. Pat. No. 4,439,409, incorporated herein by reference, and MCM-22 
of U.S. Pat. No. 4,954,325, incorporated herein by reference. 
Zeolite MCM-22 has a composition involving the molar relationship: 
EQU X.sub.2 O.sub.3 :(n)YO.sub.2, 
wherein X is a trivalent element, such as aluminum, boron, iron and/or 
gallium, preferably aluminum, Y is a tetravalent element such as silicon 
and/or germanium, preferably silicon, and n is at least about 10, usually 
from about 10 to about 150, more usually from about 10 to about 60, and 
even more usually from about 20 to about 40. In the as-synthesized form, 
zeolite MCM-22 has a formula, on an anhydrous basis and in terms of moles 
of oxides per n moles of YO.sub.2, as follows: 
EQU (0.005-0.1)Na.sub.2 O:(1-4)R:X.sub.2 O.sub.3 :nYO.sub.2 
wherein R is an organic component, e.g., hexamethyleneimine. The Na and R 
components are associated with the zeolite as a result of their presence 
during crystallization, and are easily removed by post-crystallization 
methods hereinafter more particularly described. 
Zeolite MCM-22 is thermally stable and exhibits a high surface area greater 
than about 400 m.sup.2 /gm as measured by the BET (Bruenauer, Emmet and 
Teller) test and unusually large sorption capacity when compared to 
previously described crystal structures having similar X-ray diffraction 
patterns. As is evident from the above formula, MCM-22 is synthesized 
nearly free of Na cations and thus possesses acid catalysis activity as 
synthesized. It can, therefore, be used as a component of the catalyst 
composition herein without having to first undergo an exchange step. To 
the extent desired, however, the original sodium cations of the 
as-synthesized material can be replaced in accordance with techniques well 
known in the art, at least in part, by ion exchange with other cations. 
Preferred replacement cations include hydrogen ions and hydrogen 
precursor, e.g., ammonium, ions. In its calcined form, zeolite MCM-22 
appears to be made up of a single crystal phase with little or no 
detectable impurity crystal phases and has an X-ray diffraction pattern 
including the lines listed in above Tables A-D. 
The crystalline material MCM-49 for use as catalyst component in this 
invention is described in U.S. patent application Ser. No. 5,236,575, 
entirely incorporated herein by reference, and has a composition involving 
the molar relationship: 
EQU X.sub.2 O.sub.3 :(n)YO.sub.2, 
wherein X is a trivalent element, such as aluminum, boron, iron and/or 
gallium, preferably aluminum; Y is a tetravalent element such as silicon, 
titanium, and/or germanium, preferably silicon; and n is less than about 
35, e.g., from 2 to less than about 35, usually from about 10 to less than 
about 35, more usually from about 15 to about 31. In the as-synthesized 
form, the material has a formula, on an anhydrous basis and in terms of 
moles of oxides per n moles of YO.sub.2, as follows: 
EQU (0.1-0.6)M.sub.2 O:(1-4)R:X.sub.2 O.sub.3 :nYO.sub.2 
wherein M is an alkali or alkaline earth metal, and R is an organic moiety. 
The M and R components are associated with the material as a result of 
their presence during crystallization, and are easily removed by 
post-crystallization methods hereinafter more particularly described. 
The MCM-49 for use in the invention is thermally stable and in the calcined 
form exhibits high surface area (greater than 400 m.sup.2 /gm) and 
unusually large sorption capacity when compared to previously described 
materials such as calcined PSH-3 (U.S. Pat. No. 4,439,409) and SSZ-25 
(U.S. Pat. No. 4,826,667) having similar X-ray diffraction patterns. To 
the extent desired, the original sodium cations of the as-synthesized 
MCM-49 material can be replaced in accordance with techniques well known 
in the art, at least in part, by ion exchange with other cations. 
Preferred replacing cations include metal ions, hydrogen ions, hydrogen 
precursor, e.g., ammonium, ions and mixtures thereof. Particularly 
preferred cations are those which tailor the catalytic activity for 
certain hydrocarbon conversion reactions. These include hydrogen, rare 
earth metals and metals of Groups IIA, IIIA, IVA, IB, IIB, IIIB, IVB and 
VIII of the Periodic Table of the Elements. 
In the as-synthesized form, the crystalline MCM-49 material for use in the 
invention appears to be a single crystalline phase. It can be prepared in 
essentially pure form with little or no detectable impurity crystal phases 
and has an X-ray diffraction pattern which is distinguished from the 
patterns of other known as-synthesized or thermally treated crystalline 
materials by the lines listed in Table E below: 
TABLE E 
______________________________________ 
Interplanar d-Spacing(A) 
Relative Intensity, I/I.sub.o .times. 100 
______________________________________ 
13.15 .+-. 0.26 w-s* 
12.49 .+-. 0.24 vs 
11.19 .+-. 0.22 m-s 
6.43 .+-. 0.12 w 
4.98 .+-. 0.10 w 
4.69 .+-. 0.09 w 
3.44 .+-. 0.07 vs 
3.24 .+-. 0.06 w 
______________________________________ 
*shoulder 
The X-ray diffraction peak at 13.15.+-.0.26 Angstrom Units (A) is usually 
not fully resolved for MCM-49 from the intense peak at 12.49.+-.0.24, and 
is observed as a shoulder of this intense peak. For this reason, the 
precise intensity and position of the 13.15.+-.0.26 Angstroms peak are 
difficult to determine within the stated range. 
In its calcined form, the crystalline MCM-49 material for use in the 
invention is a single crystal phase with little or no detectable impurity 
crystal phases having an X-ray diffraction pattern which is not easily 
distinguished from that of MCM-22, but is readily distinguishable from the 
patterns of other known crystalline materials. The X-ray diffraction 
pattern of the calcined form of MCM-49 includes the lines listed in Table 
F below: 
TABLE F 
______________________________________ 
Interplanar d-Spacing(A) 
Relative Intensity, I/I.sub.o .times. 100 
______________________________________ 
12.41 .+-. 0.24 vs 
11.10 .+-. 0.22 s 
8.89 .+-. 0.17 m-s 
6.89 .+-. 0.13 w 
6.19 .+-. 0.12 m 
6.01 .+-. 0.12 w 
5.56 .+-. 0.11 w 
4.96 .+-. 0.10 w 
4.67 .+-. 0.09 w 
4.59 .+-. 0.09 w 
4.39 .+-. 0.09 w 
4.12 .+-. 0.08 w 
4.07 .+-. 0.08 w-m 
3.92 .+-. 0.08 w-m 
3.75 .+-. 0.07 w-m 
3.57 .+-. 0.07 w 
3.43 .+-. 0.07 s-vs 
3.31 .+-. 0.06 w 
3.21 .+-. 0.06 w 
3.12 .+-. 0.06 w 
3.07 .+-. 0.06 w 
2.83 .+-. 0.05 w 
2.78 .+-. 0.05 w 
2.69 .+-. 0.05 w 
2.47 .+-. 0.05 w 
2.42 .+-. 0.05 w 
2.38 .+-. 0.05 w 
______________________________________ 
The above X-ray diffraction data were collected with a Scintag diffraction 
system, equipped with a germanium solid state detector, using copper 
K-alpha radiation. The diffraction data were recorded by step-scanning at 
0.02 degrees of two-theta, where theta is the Bragg angle, and a counting 
time of 10 seconds for each step. The interplanar spacings, d's, were 
calculated in Angstrom units (A), and the relative intensities of the 
lines, I/I.sub.o is one-hundredth of the intensity of the strongest line, 
above background, were derived with the use of a profile fitting routine 
(or second derivative algorithm). The intensities are uncorrected for 
Lorentz and polarization effects. The relative intensities are given in 
terms of the symbols vs=very strong (60-100), s=strong (40-60), m=medium 
(20-40) and w=weak (0-20). It should be understood that diffraction data 
listed as single lines may consist of multiple overlapping lines which 
under certain conditions, such as differences in crystallographic changes, 
may appear as resolved or partially resolved lines. Typically, 
crystallographic changes can include minor changes in unit cell parameters 
and/or a change in crystal symmetry, without a change in the structure. 
These minor effects, including changes in relative intensities, can also 
occur as a result of differences in cation content, framework composition, 
nature and degree of pore filling, and thermal and/or hydrothermal 
history. Other changes in diffraction patterns can be indicative of 
important differences between materials, which is the case for comparing 
MCM-49 with similar materials, e.g., MCM-22 and PSH-3. 
The significance of differences in the X-ray diffraction patterns of these 
materials can be explained from a knowledge of the structures of the 
materials. MCM-22 and PSH-3 are members of an unusual family of materials 
because, upon calcination, there are changes in the X-ray diffraction 
pattern that can be explained by a significant change in one axial 
dimension. This is indicative of a profound change in the bonding within 
the materials and not a simple loss of the organic material. The precursor 
members of this family can be clearly distinguished by X-ray diffraction 
from the calcined members. An examination of the X-ray diffraction 
patterns of both precursor and calcined forms shows a number of 
reflections with very similar position and intensity, while other peaks 
are different. Some of these differences are directly related to the 
changes in the axial dimension and bonding. 
The as-synthesized MCM-49 has an axial dimension similar to those of the 
calcined members of the family and, hence, there are similarities in their 
X-ray diffraction patterns. Nevertheless, the MCM-49 axial dimension is 
different from that observed in the calcined materials. For example, the 
changes in axial dimensions in MCM-22 can be determined from the positions 
of peaks particularly sensitive to these changes. Two such peaks occur at 
.about.13.5 Angstroms and .about.6.75 Angstroms in precursor MCM-22, at 
.about.12.8 Angstroms and .about.6.4 Angstroms in as-synthesized MCM-49, 
and at .about.12.6 Angstroms and .about.6.30 Angstroms in the calcined 
MCM-22. Unfortunately, the .about.12.8 Angstroms peak in MCM-49 is very 
close to the intense .about.12.4 Angstroms peak observed for all three 
materials, and is frequently not fully separated from it. Likewise, the 
.about.12.6 Angstroms peak of the calcined MCM-22 material is usually only 
visible as a shoulder on the intense .about.12.4 Angstroms peak. FIG. 1 
shows the same segment of the diffraction patterns of precursor MCM-22, 
calcined MCM-22, and MCM-49; the position of the .about.6.6-6.3 Angstroms 
peak is indicated in each segment by an asterisk. Because the .about.6.4 
Angstroms peak is unobscured in MCM-49, it was chosen as a better means of 
distinguishing MCM-49 from the calcined forms of MCM-22 and PSH-3 rather 
than the much stronger .about.12.8 Angstroms peak. Table E lists all 
diffraction peaks characteristic of MCM-49. 
MCM-49 can be prepared from a reaction mixture containing sources of alkali 
or alkaline earth metal (M), e.g. sodium or potassium, cation, an oxide of 
trivalent element X, e.g. aluminum, an oxide of tetravalent element Y, 
e.g. silicon, directing agent (R), and water, said reaction mixture having 
a composition, in terms of mole ratios of oxides, within the following 
ranges: 
______________________________________ 
Reactants Useful Preferred 
______________________________________ 
YO.sub.2 /X.sub.2 O.sub.3 
12 to &lt;35 18 to 31 
H.sub.2 O/YO.sub.2 
10 to 70 15 to 40 
OH.sup.- /YO.sub.2 
0.05 to 0.50 0.05 to 0.30 
M/YO.sub.2 0.05 to 3.0 0.05 to 1.0 
R/YO.sub.2 0.2 to 1.0 0.3 to 0.5 
______________________________________ 
In this synthesis method, if more than one X component is present, at least 
one must be present such that the YO.sub.2 /X.sub.2 O.sub.3 molar ratio 
thereof is less than about 35. For example, if aluminum oxide and gallium 
oxide components are used in the reaction mixture, at least one of the 
YO.sub.2 /Al.sub.2 O.sub.3 and YO.sub.2 /Ga.sub.2 O.sub.3 molar ratios 
must be less than about 35. If only aluminum oxide has been added to the 
reaction mixture as a source of X, the YO.sub.2 /Al.sub.2 O.sub.3 ratio 
must be less than about 35. 
In the above synthesis method, the source of YO.sub.2 must be comprised 
predominately of solid YO.sub.2, for example at least about 30 wt. % solid 
YO.sub.2 in order to obtain the crystal product of the invention. Where 
YO.sub.2 is silica, the use of a silica source containing at least about 
30 wt. % solid silica, e.g. Ultrasil (a precipitated, spray dried silica 
containing about 90 wt. % silica) or HiSil (a precipitated hydrated 
SiO.sub.2 containing about 87 wt. % silica, about 6 wt. % free H.sub.2 O 
and about 4.5 wt. % bound H.sub.2 O of hydration and having a particle 
size of about 0.02 micron) favors crystalline MCM-49 formation from the 
above mixture. Preferably, therefore, the YO.sub.2, e.g. silica, source 
contains at least about 30 wt. % solid YO.sub.2, e.g. silica, and more 
preferably at least about 40 wt. % solid YO.sub.2, e.g. silica. 
Directing agent R is selected from the group consisting of cycloalkylamine, 
azacycloalkane, diazacycloalkane, and mixtures thereof, alkyl comprising 
from 5 to 8 carbon atoms. Non-limiting examples of R include 
cyclopentylamine, cyclohexylamine, cycloheptylamine, hexamethyleneimine, 
heptamethyleneimine, homopiperazine, and combinations thereof. 
Crystallization of MCM-49 crystalline material can be carried out at either 
static or stirred conditions in a suitable reactor vessel, such as for 
example, polypropylene jars or teflon lined or stainless steel autoclaves. 
The total useful range of temperatures for crystallization is from about 
80.degree. C. to about 225.degree. C. for a time sufficient for 
crystallization to occur at the temperature used, e.g. from about 24 hours 
to about 60 days. Thereafter, the crystals are separated from the liquid 
and recovered. 
It should be realized that the reaction mixture components can be supplied 
by more than one source. The reaction mixture can be prepared either 
batchwise or continuously. Crystal size and crystallization time of MCM-49 
crystalline material will vary with the nature of the reaction mixture 
employed and the crystallization conditions. 
Synthesis of MCM-49 may be facilitated by the presence of at least 0.01 
percent, preferably 0.10 percent and still more preferably 1 percent, seed 
crystals (based on total weight) of crystalline product. Useful seed 
crystals include those having the structure of MCM-49. 
Prior to its use as catalyst, the zeolite crystals should be subjected to 
thermal treatment to remove part or all of any organic constituent present 
therein. This thermal treatment is generally performed by heating at a 
temperature of at least about 370.degree. C. for at least 1 minute and 
generally not longer than 20 hours. While subatmospheric pressure can be 
employed for the thermal treatment, atmospheric pressure is preferred 
simply for reasons of convenience. 
The zeolite crystals for use herein can be shaped into a wide variety of 
particle sizes. Generally speaking, the particles can be in the form of a 
powder, a granule, or a molded product such as an extrudate having a 
particle size sufficient to pass through a 2 mesh (Tyler) screen and be 
retained on a 400 mesh (Tyler) screen. In cases where the catalyst is 
molded, such as by extrusion, the crystals can be extruded before drying 
or partially dried and then extruded. 
It may be desired to incorporate the crystalline material with another 
material which is resistant to the temperatures and other conditions 
employed in the condensation process of this invention. Such materials 
include active and inactive materials and synthetic or naturally occurring 
zeolites as well as inorganic materials such as clays, silica and/or metal 
oxides such as alumina, magnesia, zirconia, thoria, beryllia, and/or 
titania. The latter may be either naturally occurring or in the form of 
gelatinous precipitates or gels including mixtures of silica and metal 
oxides. Use of a material in conjunction with the zeolite, i.e., combined 
therewith or present during its synthesis, which itself is catalytically 
active may change the conversion and/or selectivity of the catalyst. 
Inactive materials suitably serve as diluents to control the amount of 
conversion so that the products can be obtained economically and orderly 
without employing other means for controlling the rate of reaction. These 
materials may be incorporated into naturally occurring clays, e.g., 
bentonite and kaolin, to improve the crush strength of the catalyst under 
commercial operating conditions. Said materials, i.e., clays, oxides, 
etc., function as binders for the catalyst. It is desirable to provide a 
catalyst having good crush strength because in commercial use it is 
desirable to prevent the catalyst from breaking down into powder-like 
materials. These clay binders have been employed normally only for the 
purpose of improving the crush strength of the catalyst. 
Naturally occurring clays which can be composited with zeolite crystals 
include the montmorillonite and kaolin families which include the 
subbentonites and the kaolins commonly known as Dixie, McNamee, Georgia 
and Florida clays or others in which the main mineral constituent is 
halloysite, kaolinite, dickite, nacrite or anauxite. Such clays can be 
used in the raw state as originally mined or initially subjected to 
calcination, acid treatment or chemical modification. 
In addition to the foregoing materials, the crystals can be composited with 
a porous matrix material such as silica-alumina, silica-magnesia, 
silica-zirconia, silica-thoria, silica-beryllia, silica-titania as well as 
ternary compositions such as silica-alumina-thoria, 
silica-alumina-zirconia, silica-alumina-magnesia and 
silica-magnesia-zirconia. It may also be advantageous to provide at least 
a part of the foregoing matrix materials in colloidal form so as to 
facilitate extrusion of the bound catalyst components. 
The relative proportions of finely divided crystalline material and 
inorganic oxide matrix vary widely, with the crystal content ranging from 
about 1 to about 90 percent by weight and more usually, particularly when 
the composite is prepared in the form of beads, in the range of about 2 to 
about 80 weight percent of the composite. 
The carbonyl reactant taking part in the catalytic reaction described 
herein may be formaldehyde, an aldehyde containing 2 to 4 carbon atoms, a 
ketone containing 3 to 5 carbon atoms, or mixtures thereof. Representative 
reactant aldehydes include acetaldehyde, propionaldehyde, acrolein, 
butyraldehyde, and crotonaldehyde. Representative reactant ketones include 
acetone, methyl ethyl ketone, diethyl ketone, and methyl propyl ketone. 
Mixtures, of course, may be used as reactants in the process of this 
invention. 
The present improved process involving reaction between carbonyl compound 
and ammonia is effectively carried out at a temperature from about 
285.degree. C. to about 600.degree. C., preferably from about 340.degree. 
C. to about 550.degree. C., at a pressure from about 0.2 atmosphere to 
about 20 atmospheres, preferably from about 0.8 atmosphere to about 10 
atmospheres, utilizing a gas hourly space velocity of from about 200 to 
about 20,000 hr.sup.-1, and preferably from about 300 to about 5,000 
hr.sup.-1. 
The mole ratio of ammonia to carbonyl reactant in the reaction mixture 
employed will generally be between about 0.5 and about 10 and more usually 
between about 1 and about 5. Hydrogen may, if desired, be added to the 
reaction at the rate of from 0 (no added hydrogen) to about 5,000 cc/hour, 
preferably from 0 to about 1,000 cc/hour. 
At the completion of the reaction, the product may be separated into its 
desired components by any feasible means, e.g., by fractionation, to 
recover a product containing the pyridine or the 3-alkylpyridine compound. 
Of the 3-alkylpyridine compounds selectively produced by way of the 
present invention, 3-picoline is an important intermediate in the 
manufacture of 3-pyridinecarboxylic acid, i.e., nicotinic acid, and other 
medicinal, agricultural, and chemical products. These products have 
important pharmaceutical significance as well as being used as additives 
in food and feeds. Another of the compounds selectively produced by way of 
the present invention is pyridine. This latter compound is an important 
chemical used in the manufacture of herbicides and pesticides. It is also 
used as a solvent in the textile industry. 
An important aspect of the present invention involves synthesis of 
3-pyridinecarboxylic acid by the integrated process comprising (1) 
synthesis of 3-picoline by reacting ammonia, acetaldehyde and formaldehyde 
in the presence of catalyst comprising synthetic porous crystalline 
material MCM-49 and/or one characterized by an X-ray diffraction pattern 
including interplanar d-spacings at 12.36.+-.0.4, 11.03.+-.0.2, 
8.83.+-.0.14, 6.18.+-.0.12, 6.00.+-.0.10, 4.06.+-.0.07, 3.91.+-.0.07, and 
3.42.+-.0.06 Angstroms at reaction conditions including a temperature of 
from about 285.degree. C. to about 600.degree. C., a pressure of from 
about 0.2 atmospheres to about 20 atmospheres and a gas hourly space 
velocity of from about 200 hr.sup.-1 to about 20,000 hr.sup.-1, (2) 
recovering the 3-picoline product of the synthesis step (1), and oxidizing 
the 3-picoline of step (2) by, for example, contacting same with an 
oxidative reagent, such as KMnO.sub.4 or the like. 
The following examples will serve to illustrate the present invention 
without limiting same. 
EXAMPLE 1 
Zeolite MCM-22 was prepared as in U.S. Pat. No. 4,954,325, incorporated 
herein by reference, combined with alumina binder and extruded to form 65 
wt. % MCM-22/35 wt. % alumina extrudate catalyst. The hydrogen form of 
this material was prepared by ammonium exchange (i.e., with 1N NH.sub.4 
NO.sub.3 at room temperature) followed by calcination at 538.degree. C. in 
air. 
A sample of the MCM-22 catalyst was loaded into a micro-reactor and heated 
to 427.degree. C. under a nitrogen atmosphere. The reaction was run at 
427.degree. C. with ammonia flow of 578 cc/hour, hydrogen flow of 253 
cc/hour, and with a mixture of 1 wt. portion of acetaldehyde and 1.3 wt. 
portion of formaline (37 wt. % formaldehyde) at 3.2 cc/hour. The GHSV 
(NH.sub.3) was 580 hr.sup.-1. The reaction mixture molar ratio of 
acetaldehyde/formaldehyde/NH.sub.3 /H.sub.2 was 1.4/1/3.6/1.6. After an 
hour on stream, the products were condensed and analyzed. 
The pyridine and 2-, 3-, and 4-picoline yields were obtained by analyzing 
the liquid product on a 30 m.times.0.25 mm ID fused silica gas 
chromatographic column with a 0.25 .mu.m thick polyethylene glycol-acid 
modified (DB-FFAP) phase. Gas chromatography-mass spectrometry was used to 
confirm the identity and homogeneity of the chromatographic peaks. The 
pyridine and picolines were quantified using quinoline as the internal 
standard. Results are summarized in Table G. 
EXAMPLE 2 
For comparison purposes, zeolite ZSM-5 was prepared as in European Patent 
No. 130,809, incorporated herein by reference, combined with alumina 
binder and extruded to form 65 wt. % ZSM-5/35 wt. % alumina extrudate 
catalyst. The hydrogen form of this material was prepared by ammonium 
exchange (i.e., with 1N NH.sub.4 NO.sub.3 at room temperature) followed by 
calcination at 538.degree. C. in air. ZSM-5 has been the preferred zeolite 
used commercially for pyridine synthesis. 
A sample of the ZSM-5 catalyst was loaded into the micro-reactor and the 
reaction was run and the product analyzed under the same conditions as 
described in Example 1. Results are summarized in Table G. 
TABLE G 
______________________________________ 
Example 1 2 
______________________________________ 
Catalyst MCM-22 ZSM-5 
Product Selectivity, wt. % 
Pyridine 9.3 9.5 
2-Picoline 0.6 0.6 
3-Picoline 4.1 3.7 
4-Picoline 0.9 0.7 
Total Picolines, wt. % 
5.6 5.0 
3-Picoline, % per charge 
4.47 3.58 
Pyridine, % per charge 
10.14 9.18 
______________________________________ 
These examples confirm the improvement of the present invention. Catalysts 
comprising the presently required zeolite are significantly more active 
and more selective than catalyst comprising ZSM-5 for the process of this 
invention. 
EXAMPLE 3 
A sample of recovered 3-picoline from Example 1 is contacted with the 
oxidative reagent KMnO.sub.4 in an organic solvent at refluxing 
temperature for 2 hours. The reaction is then treated with water and the 
reactants filtered. Product pyridine-3-carboxylic acid, i.e., nicotinic 
acid, is then extracted from the reaction mixture, e.g., with 
ethylacetate, and recovered.