Catalyst derived from mixture of manganese hydroxide and magnesium-containing material, and method of use in ortho-alkylation of phenols

A catalyst precursor prepared by precipitating manganese hydroxide from caustic solution and then mixing the precipitate with a magnesium-containing material is described. The catalyst precursor can be calcined to an active form, and the resulting catalyst can be used to effect or facilitate the ortho-alkylation of phenolic compounds in vapor phase reactions. Superiority of performance is demonstrated with respect to a catalyst derived from a precursor in which manganese hydroxide is precipitated (sometimes referred to as "co-precipitation") in the presence of a magnesium compound, rather than formed separately. y

BACKGROUND OF THE INVENTION 
Phenolic compounds containing alkyl substituents in the ortho position on 
the ring are useful as starting materials for the preparation of 
polyphenylene oxide resins. In general, these compounds are prepared by 
catalyzed processes in which one or more phenolic compounds are reacted 
with an alkyl alcohol in the vapor phase. A number of specific procedures 
are described in the patent literature. 
Processes designed for the ortho-methylation of phenols are disclosed by 
Hamilton, in U.S. Pat. Nos. 3,446,856 and 3,479,410. The first employs 
magnesium oxide as a catalyst at a temperature from 475.degree. to 
600.degree. C. The second uses magnesium oxide or calcium phosphate, under 
similar conditions. In both cases, the magnesium oxide can be derived by 
thermal decomposition of magnesium carbonate, which can occur using the 
same temperatures as employed in the ortho-alkylation reaction. In 
addition, Van Sorge, in U.S. Pat. No. 3,972,828, describes an 
ortho-alkylation catalyst consisting of powdered magnesium oxide together 
with an inert polymeric binder. 
Catalysts based on both magnesium and manganese have been found useful in 
ortho-alkylation reactions. Some of these are formed by co-precipitation, 
others by dry blending. In co-precipitation, manganous hydroxide is 
precipitated from a solution of a manganese salt in the presence of a 
magnesium source, e.g., magnesium carbonate. Precipitation can be induced 
by heating, by the addition of a caustic, e.g., potassium or sodium 
hydroxide, or addition of ammonium hydroxide. These kinds of procedures 
are described in copending U.S. applications Ser. Nos. 163,452 and 
163,486, both filed Jun. 27, 1980 and assigned to the same assignee as 
herein. Dry blending techniques, on the other hand, are based in general 
on the admixing of magnesium oxides with manganese oxides or of compounds 
of the two which are capable of conversion into oxides upon calcination. 
See, for example, U.S. Pat. No. 3,873,628(mixing magnesium oxide and 
manganese sulfate, heating to dryness, and calcining), and U.S. Pat. Nos. 
3,972,836 and 3,974,229(blending powders of magnesium oxide and manganese 
oxide). 
Many of the above mentioned types of magnesium manganese catalysts suffer 
from shortcomings of one kind or another. Those which employ caustic 
co-precipitation techniques usually result in a catalyst which must be 
thoroughly washed to remove residual amounts of sodium or potassium ions. 
The use of ammonia is often objectionable because of the strong odor. 
Procedures in which sulfates are the manganese source can result in giving 
off malodorous fumes. 
INTRODUCTION TO THE INVENTION 
The discovery has now been made that a catalyst precursor having the 
capability of being calcined to a highly active state can be prepared by 
admixing a magnesium containing material with manganese hydroxide, in 
which the manganese hydroxide has been preformed separately by 
precipitation from an aqueous mixture of a manganese salt solution and a 
caustic solution. The precursor can be calcined to a catalyst which is 
useful in a process for the ortho-alkylation of phenols. In comparison 
with a catalyst precursor made by the precipitation of manganese hydroxide 
from hot solution in the presence of the magnesium compound, the present 
kind of precursor after calcining exhibits better activity, as is shown in 
comparative test experiments described in this disclosure and in the 
accompanying drawing. 
This invention thus comprises several aspects. One aspect is the catalyst 
precursor itself; that is, the catalyst prior to being activated. Another 
aspect is the catalyst precursor having been formed by a certain specific 
combination of process steps, to be described below. A third aspect is a 
process for the formation of the active catalyst, including a calcining 
treatment. A fourth aspect is the catalyst formed by this process, which 
is shown to be different from another catalyst formed from the same 
starting materials, but using different process steps. Finally, another 
aspect comprises an improved method for the ortho-alkylation of phenolic 
compounds, using the described catalyst.

DESCRIPTION OF THE INVENTION 
The catalyst precursor is formed as a mixture of a magnesium-containing 
material and manganese hydroxide. The manganese hydroxide is derived by 
bringing together an aqueous solution of a soluble manganese compound and 
an aqueous caustic solution. Suitable manganese compounds, which may be 
used individually or in admixture as the source of manganese, include 
relatively soluble compounds such as manganese nitrate, manganese sulfate 
and manganese acetate. Also contemplated, however, are other water soluble 
materials, such as manganese chloride, manganese bromide, and the like. 
By way of illustration, a solution of the manganese compound or compounds 
in water is formed and to it is gradually added a solution of a caustic in 
water. The caustic may be an alkali metal salt, such as sodium hydroxide 
or potassium hydroxide. The addition is accompanied with stirring and will 
normally take place over a period from about 10 to 30 minutes, during 
which a precipitate of manganese hydroxide forms. The procedure may be, 
and preferably is, conducted at or near room temperature, e.g., about 
25.degree. C. Recovery of the manganese hydroxide may be accomplished by 
filtration or centrifugation, after which it is preferably washed, dried 
to remove most of the moisture, and then ground or pulverized into a fine 
powder, for example, from 25 to 50 mesh, U.S. Standard Sieve. 
The manganese hydroxide formed in this manner is then blended with a 
magnesium material. Suitable magnesium materials include magnesium 
carbonate, basic magnesium carbonate and magnesium hydroxide, individually 
or in admixtures of two or more. The term "basic magnesium carbonate" 
refers to those materials represented by the formula 
EQU xMgCO.sub.3 .multidot. 
EQU Mg(OH).sub.2 .multidot. 
EQU xH.sub.2 O 
in which each x independently is a number average from about 3 to 5. 
Preferably, the magnesium material is basic magnesium carbonate, and 
especially in finely divided form. 
The manganese compound and magnesium material can be employed in varying 
proportions to form the catalyst precursor, but preferably they are used 
in amounts so as to provide from about 0.02 to about 0.25 moles of 
manganese for each mole of magnesium in the final catalyst composition. 
The catalyst precursor, comprising a mixture of finely divided particles of 
magnesium material and manganese hydroxide, is then preferably blended 
with a binder material or materials to facilitate shaping and subsequent 
processing. As a binder material there may be used various inorganic or 
organic substances, both polymeric and non-polymeric. The preferred binder 
is a polymer, and especially preferred are polyphenylene ether resins such 
as those which are described by Allan Hay in U.S. Pat. Nos. 3,306,874 and 
3,306,875. Polyphenylene ether copolymers may also be used. The 
polyphenylene ether resin, for instance, may be compounded with the 
catalyst precursor particles in an amount from about 0.1 up to about 20% 
by weight. The polymer can be used alone or together with other materials, 
such as powdered graphite or a similar shaping aid in an amount of up to 
about 3.0 % by weight. 
The mixture of catalyst precursor particles and binder is then shaped into 
the desired form, which may be accomplished using virtually any suitable 
shaping method or device. Illustratively, and preferably, the solid 
mixture is formed into tablets on a press, utilizing conventional 
conditions. Alternatively, the mixture of particles can also be shaped 
into cylinders, pellets, or any of the other forms conventional for 
catalyst preparation. 
After being shaped, the catalyst precursor is activated for use by being 
subjected to a calcining treatment under time and temperature conditions 
sufficient to produce an active catalyst. Typically, the treatment 
involves heating the precursor to a temperature of at least 300.degree. 
C., or sufficient to convert the magnesium and manganese compounds to a 
mixture of oxides. Temperatures of between approximately 350 and 
500.degree. C. for a period of about 34 hours are preferred, but 
temperatures as high as 550 .degree. C. may be used. Calcining can be 
effected in a variety of environments, including air, an inert gas, e.g., 
nitrogen, or under vacuum. The calcination treatment may be carried out 
prior to loading into a reactor, or alternatively, in situ in the reactor 
itself, and optionally in the presence of a feed stream of the reactants. 
During the calcining step, it will be found that minute pores form in the 
catalyst, thereby exposing more surface area, which is beneficial to the 
ultimate performance. A surface area of at least 25, and preferably from 
25 to 450, square meters per gram of catalyst weight is very desirable and 
will normally be achieved using the conditions which have been described. 
The catalyst prepared in the aforementioned manner may be employed to 
effect or facilitate the ortho-alkylation of phenolic compounds, such as 
those having the formula 
##STR1## 
in which each R, independently, is a monovalent substituent selected from 
the group consisting of hydrogen, alkyl (preferably C.sub.1 to C.sub.12 
alkyl), phenyl, and alkyl substituted phenyl (preferably C.sub.1 to 
C.sub.12 alkyl substituted phenyl). 
The alkyl alcohol which is the co-reactant in the process is preferably a 
branched or linear saturated alcohol having up to 16 carbon atoms, such as 
methyl, ethyl, propyl, isopropyl, butyl, isobutyl, tert.-butyl, amyl, 
isoamyl, hexyl, heptyl, octyl, nonyl, decyl, lauryl, cetyl, cyclohexyl, 
and the like. Especially preferred are alcohols having up to 6 carbon 
atoms, with methanol being the most preferred. 
By way of illustrating the practice of the process, any one or a mixture of 
phenols having an ortho hydrogen is vaporized and, together with an alkyl 
alcohol, is passed through a reactor heated to a temperature of at least 
300.degree. C., preferably from about 400 .degree. to 500.degree. C., and 
containing a catalyst prepared as described. For the most favorable 
results, it is advisable to use at least one mole of the alkyl alcohol, 
and preferably from one to three moles, for each ortho position on the 
phenol to be alkylated. For example, if phenol, which has two ortho 
hydrogens per molecule, is to be methylated to produce 2, 6-xylenol in 
optimum yields, it is desirable to employ from two to six moles of 
methanol for each mole of phenol, the larger yields being obtained with 
use of the higher ratios of methanol to phenol. 
The ortho-alkylation process can be carried out under a variety of reaction 
conditions of temperature, pressure, flow rate of reactants, vapor space 
velocity of reactants over catalyst, contact time of reactants with 
catalyst, length of catalyst feed, and so forth. Above a temperature of 
500.degree. C., however, decomposition of the reactants and products often 
becomes a problem, and such temperatures should be avoided. 
Generally, the reaction conditions are regulated to minimize the amount of 
unreacted feed materials which must be recovered and reused, and to 
maximize the percentage of selectivity to the desired ortho-alkylated end 
products, that is, phenolic compounds having an alkyl substituent in the 
"2" or both the "2" and "5" positions (relative to the hydroxy group) on 
the ring. 
While the reaction proceeds at atmospheric pressure, which is preferred, 
superatmospheric pressures or subatmospheric pressures can be used if 
desired. 
The vapors issuing from the reactor are condensed, and the products are 
separated by conventional methods, such as crystallization or 
distillation. 
Using the present catalyst, yields of the desired ortho-alkylated end 
product are good, with selectivity being favored over meta and para 
alkylations. 
DESCRIPTION OF THE SPECIFIC EMBODIMENTS 
The invention in its various aspects is illustrated in the following 
examples, which are not to be construed as limiting. 
EXAMPLE 1 
A catalyst precursor in accordance with the invention was prepared as 
follows: 
An amount consisting of 16.1 grams of a 50% aqueous solution of sodium 
hydroxide was dissolved in 250 milliliters of distilled water, then placed 
in an addition funnel. Separately, 35.8 grams of a 50% by weight solution 
of manganous nitrate was dissolved in 500 milliliters of distilled water. 
The sodium hydroxide solution was added gradually to the manganese nitrate 
solution, with stirring, at a rate of 5 to 10 milliliters per minute, 
during which a precipitate comprising manganese hydroxide formed. The 
mixture was filtered to separate the mother liquor from the precipitate, 
using a 600-milliliter-capacity medium fritted filter. After the 
filtration was completed, 250 milliliters of distilled water were poured 
into the filter cake, which was still wet, and using a handheld 
homogenizer the cake was resuspended in the water, after which it was 
vacuum filtered. The procedure was repeated four more times to thoroughly 
clean the precipitate. The wet filter cake was left in the fritted funnel 
and placed in a vacuum oven at a temperature of 108.degree. C. overnight 
to dry. The dried cake was removed from the oven the following morning, 
ground through a No. 25 sieve, and blended with magnesium carbonate on a 
jar mill using a weight ratio of 2.5:97.5 of manganese hydroxide:magnesium 
carbonate. The blend was, in turn, mixed with 
poly(2,6-dimethyl-1,4-phenylene ether)resin (PPO.RTM., General Electric 
Company), also on the jar mill, using amounts to provide a 90:10 ratio of 
catalyst precursor:PPO. The resulting mixture of solids was formed into 
3/16 inch by 150 inch tablets on a tabletting press. 
For purposes of comparison, a catalyst precursor in accordance with the 
prior art was prepared as follows: 
518.9 grams of basic magnesium carbonate having four waters of hydration 
(the formula above in which x =4) was slurried in 2000 milliliters of 
distilled water. Forty grams of a 50% by weight aqueous manganous nitrate 
solution was diluted with 450 milliliters of water, and then added 
gradually to the slurry over a 5-minute period, with stirring. The 
resulting mixture was blanketed with a stream of nitrogen gas and 
maintained at a temperature of 80.degree. C., for 3 hours, with stirring 
continued. A precipitate of manganese hydroxide was formed. The 
precipitate was centrifuged to separate it from the mother liquor, and 
then oven dried. The resulting dried powder was blended with 
poly(2,6-dimethyl-1,4-phenylene ether)resin (PPO) of less than 140 mesh 
particle size, using a 90:10 by weight ratio of catalyst precursor to 
PPO.RTM.. Powdered graphite was added (Asbury Chemical's 99) in an amount 
of 0.5% by weight, and the graphite-containing mixture was compacted using 
a roller mill, screened, and formed into 3/16 inch by 150 inch tablets. 
EXAMPLE 2 
The catalyst precursors of Example 1 were then calcined to activate them 
for use in a process for the ortho-methylation of a phenolic compound. In 
both cases, calcination was conducted in situ in an ortho-alkylation 
reactor, which is described as follows: 
THE REACTOR 
The Reactor comprises two stainless steel tubes, both disposed along a 
verticle axis, one of which has a length of 15 inches (38.1 centimeters), 
the other of which has a length of 24 inches (60.96 centimeters), and both 
of which have an inner diameter of 3/4inch (1.91 centimeters). The first 
functions as a vaporizer. The second is filled to a depth of two inches 
with glass beads that serve as a support for the catalyst and functions as 
a reactor. Both are partially immersed in a fused salt bath, the first to 
a depth of 8 inches (20.3 cm), the second to a depth of 17 inches (43.2 
cm). The first (vaporizer) and second (reactor) tubes are joined by a 
third tube, consisting of a two inch long (5.1 cm) steel pipe connected at 
one end to an opening in the first tube 5 inches (12.7 cm) from its 
bottom, and at the other end to an opening in the second tube 14 inches 
(35.6 cm) from its bottom. The connector tube also passes through the 
fused salt bath. 
In practice, a feed stream comprising the reactants is sent from a 
reservoir, through a metering pump, into the first (vaporizer) tube, where 
the feed stream is heated to a temperature high enough to volatilize the 
constituents. The vapors emitting from the vaporizer tube pass through the 
interconnecting pipe, which serves as a preheater to bring the vapors up 
to the temperature of the reactor tube. The vapors are fed from there to 
the reactor tube and the catalyst bed, where reaction takes place. Product 
vapors leave the bottom of the reactor tube through a stainless steel 
outlet tube, having an inner diameter of 3/8 inch (0.95 cm), and are led 
to a water-cooled condenser and receiver where they are liquefied and 
recovered. The non-condensible materials are fed to an off-gas meter, 
where they can be measured. 
In each case, the reactor was charged with 110 ml. of the catalyst 
precursor, capped, and placed in the fused salt bath at a temperature of 
370 .degree. C., after which a stream of gaseous nitrogen was blown over 
the catalyst bed at a rate of 2 standard cubic feet per hour (SCFH). After 
15 minutes, a feed stream of the reactants was started. The feed comprised 
a mixture of methanol, phenol and orthocresol, in a 4:1 ratio by weight of 
methanol to phenolics. The weight ratio of phenol to ortho-cresol was 
60:40. The feed also contained about 20% water. The feed rate was held at 
215 ml/hour, which was equivalent to a liquid hourly space velocity (LHSV) 
of 1.95. The pressure for this experiment was maintained at one 
atmosphere. 
After the temperature of the feed was established at 370 .degree. C., it 
was raised to 458.degree. C. where it was maintained throughout the run. 
The product stream was sampled periodically to analyze for the 
constituents. The percentages of unreacted phenol and orthocresol, of 
2,6-xylenol (the desired end product), and of 2,4,6-trimethyl phenol (a 
byproduct) were calculated, and from these data the selectivity to the 
dessired end product was also computed. The test results are reported in 
Table 1 below. 
TABLE 1 
__________________________________________________________________________ 
Time, 
Off Gas, 
Wt. % 
Wt. % Wt. % 
Wt. % 
Catalyst 
hrs. 
SCFH Phenol 
O--Cresol 
2,6 2,4,6 
Selectivity 
__________________________________________________________________________ 
This 506 0.684 
3.03 
21.05 71.08 
4.20 
16.9 
Invention 
Comparison 
506 0.537 
3.99 
24.89 65.66 
4.80 
13.7 
__________________________________________________________________________ 
The results are plotted in the accompanying FIGURE. As can be seen, the 
process conducted in accordance with the invention produces a distinctly 
higher yield of 2,6-xylenol (the top line in the graph), over virtually 
the entire duration of the run. 
EXAMPLE 3 
The procedure of Example 2 was repeated, with the exception that the 
reaction was conducted using a pressure equivalent to 25 atmospheres and a 
temperature of about 435 to 440.degree. C. The comparative results are 
listed in Table 2 below. 
TABLE 2 
__________________________________________________________________________ 
Time, 
Off Gas 
Wt. % 
Wt. % Wt. % 
Wt. % 
Catalyst 
hrs. 
SCFH Phenol 
O--Cresol 
2,6 2,4,6 
Selectivity 
__________________________________________________________________________ 
This 342 0.735 
1.78 
11.85 75.44 
9.61 
7.9 
Invention 
Comparison 
190* 
0.237 
3.99 
21.92 60.66 
11.16 
5.4 
__________________________________________________________________________ 
*Run stopped at 190 hours due to plugged reactor 
All of the above mentioned patents are incorporated herein by reference. 
Other variations and modifications of the invention are possible, and 
changes may be made in the specific embodiments shown which are within the 
scope of the invention defined in the appended claims.