This invention relates to the area of chemistry and petrochemistry,
more precisely to a process for producing p-cumylphenol (PCP) by means of
catalytic alkylation of phenol with &agr;-methylstyrene (AMS).
p-Cumylphenol is widely used in producing effective stabilizers for fuels,
oils, polymers, and rubbers.
Processes are known for producing p-cumylphenol
using homogeneous acidic catalysts, such as strong mineral acids: sulfuric, oxalic,
phosphoric, etc. [a) Kumok, Gurvich, Stiskin, Grinberg. Zh. Vses. Khim. Obshchestva
im. Mendeleeva 17:4.460-462 (1972); b) US patent no. 24441408 (1948); c) US
patent 2751437 (1950)]. The disadvantages of this process are typical for the use
of homogeneous catalysts. These are the low selectivity of the process, the difficulty
of separating the catalytic complex from the reaction products, and ecological problems
connected with the use of strong acids.
The indicated disadvantages are not present in the process
for producing p-cumylphenol which uses heterogeneous catalysts, for example
based on synthetic zeolites of the type of dealuminated mordenite or zeolites of
the ZSM family, which are prepared with or without a binder and with the addition
of promoter metals or without additives [US patent no. 4409412 (1982)]. The disadvantage
of using catalysts of this type is their insufficient activity and increased formation
of side products. For example, when PCP is made by this method, dimer side products
are also produced. Specifically, when this reaction is carried out at a temperature
of 100° C, a raw material volumetric feed rate of 1 h-1, using dealuminated
mordenite as the catalyst, the content of the end product PCP in the catalysis product
is 12-13% by mass, with the dimer content being greater than 4% and the
o-cumylphenol content being 0.5-0.7% (wherein the dimer and o-cumylphenol
content is greater than 4.5%). When a sample of TsVM zeolite (a member of the ZSM-5
family) is used as catalyst quality of end product PCP is 11-12%, the dimer content
is 0.6-0.7%, the o-cumylphenol content is about 2.2%, and the total content
of dimer and o-cumylphenol is greater than 2.8%. (more than 2.8%), respectively.
In another known process for producing PCP, an ion-exchange
resin of the type of Amberlyst in the hydrogen form is used as the catalyst [US
patent 5185475 (1993) - prototype].
At a temperature of 80-110° C, under atmospheric pressure,
and with a raw material volume feed rate of 1.0 h-1, the content of PCP
in the catalysis product is 16.2-16.5%, the content of dimers is around 0.3-0.5%,
and the content of o-cumylphenol is 4.4% (the total of the latter two is
greater than 4.6%). The disadvantages of the PCP synthesis process using ion-exchange
resins as catalyst which is proposed as a prototype are as follows:
- increased content of side products (o-cumylphenol and dimers);
- insufficient activity of the catalyst;
- low thermal stability of the catalyst, lowering its service life;
- difficulty of regenerating the catalyst;
- necessity of additional purification of the reaction products on alkaline sorbents
to remove acidic components which are washed out of the catalyst.
EP-A-360874 discloses the preparation of p-cumylphenol
from phenol and &agr;-methylstyrene in the presence of inorganic solid acid catalysts,
such as activated clays, and an inert gas.
The goal of this invention is to increase the activity
and selectivity and to simplify the technology of the process for producing
The indicated goal is achieved by alkylating phenol with
&agr;-methylstyrene using a heterogeneous acidic aluminum zirconium catalyst at
a temperature of 80-110° C.
Also, a relative raw material volumetric feed rate must
be maintained through the catalyst bed as necessary to provide a space velocity
of 1-3 h-1 (hereinafter referred to as a "volume feed rate").
The catalyst represents a mixture of aluminum oxide and
zirconium oxide promoted by sulfate, with the total content of aluminum and zirconium
sulfates being from 5 to 15% by mass (calculated on the basis of SO4
ions) and the total content of aluminum oxide and sulfate being 5-30% by mass (calculated
on the basis of Al2O3).
As a rule, aluminum oxide carriers of catalysts are prepared
by precipitation of aluminum hydroxide from a solution of sodium aluminate using
concentrated nitric acid at a pH of 8.7-8.9 in two streams: "cold" precipitation
at 18-20° C and "hot" precipitation at 100-120° C. Mixing these streams
in different proportions makes it possible to regulate the quality of the product.
The resulting mass of aluminum hydroxide is washed of sodium ions, plasticized,
peptized, and molded into granules of a given size in screw extruders [USSR patent
no. 1559494 (1986), Russian Federation patent no. 2058189, published in
Biulleten' izobretenii [Russian Patent Office Journal] no. 11 on 4/20/96].
Aluminum zirconium catalysts used for various syntheses
are prepared by the process of precipitating zirconium oxychloride (ZrOCl2·8H2O)
with an aqueous ammonia solution and then drying the resulting precipitate and treating
it with 1 N sulfuric acid. For molding into granules the sulfonated powdered zirconium
oxide is mixed with aluminum hydroxide, which is used as a binder [J. Catal.
For example, a process is known of preparing an aluminum
zirconium catalyst for isomerization of paraffin hydrocarbons [US patent 6326328
(2001)]. The indicated process involves taking a mixture of powdered zirconium and
aluminum hydroxides with the addition of a sulfonating agent - ammonium sulfate
salts, mixing it, extruding it, and roasting the resulting granules at 600°
C. Aluminum hydroxide or hydrated aluminum hydroxide are used as a binder. However,
a catalyst prepared according to this process is not suitable for producing PCP,
since it does not have sufficient activity.
The process for preparing the proposed composition of the
p-cumylphenol synthesis catalyst by means of alkylating phenol with &agr;-methylstyrene
includes stages of precipitating zirconium hydroxide, mixing zirconium and aluminum
hydroxides, sulfating hydroxides, peptizing the electrolyte solution, screw extrusion
of the catalyzed mass, and heat treatment. The starting aluminum compound that is
used is aluminum hydroxide, consisting of boehmite and pseudoboehmite in a mass
ratio of 1:3 to 3:1 (calculated on the basis of Al2O3). Sulfuric
acid is used as the sulfating and peptizing agent.
The essential characterizing features of the proposed process
for preparing the catalyst are the use of a mixture of boehmite and pseudoboehmite
in the indicated ratio at the stage of preparing aluminum hydroxide, and also using
an aqueous sulfuric acid solution at the stage of sulfation and peptization of the
catalyzed mass. The catalyst produced according to the proposed process based on
sulfated aluminum and zirconium oxides can be regenerated both by means of treatment
with heated gas (nitrogen) and by means of washing with a solvent, for example phenol.
This catalyst is significantly cheaper than ion-exchange
resins and, as will be shown in below in the examples, has high activity and selectivity
in the proposed process. We are not aware of processes for preparing aluminum zirconium
catalysts of the proposed composition.
The industrial applicability of the proposed catalyst for
the synthesis of p-cumylphenol by alkylation of phenol with &agr;-methylstyrene
and the process of preparing it are confirmed by the following examples.
a) Preparation of Catalyst
431 g of the salt ZrOCl2·8H2O
are dissolved in 5.2 L of distilled water. 332 mL of NH4OH solution having
a concentration of about 25% is dripped into the resulting solution over 20 minutes.
The resulting precipitate is filtered off and washed with water on a Büchner
funnel to remove ammonium chloride. The resulting washed precipitate is dried in
a drying cabinet at 110° C for 24 hours. The dried precipitate is ground in
a mill, and the resulting fine powder is sifted in a 180 µm sieve. The mass
of the powder is 190 g or 147 g, calculated on the basis of ZrO2.
To sulfate the powder, it is treated with 1.14 L of 1 N
sulfuric acid solution for 1 hour. Then, the resulting mixture is filtered to remove
excess solution, and the product is dried at 110° C (10 h) and is further used
To produce pseudoboehmite, 3 L of a 100 g/L sodium aluminate
solution is used. The precipitation is performed by simultaneously pouring together
the indicated aluminate solution and a 60% solution of nitric acid (yield: 1.8 L)
at a temperature of 20-25° C and at a pH in the range 9.1 to 9.5 over the course
of 2 hours. After the solutions have been completely poured in, the suspensions
are stabilized by boiling (102-105° C) at a pH that is kept constant in the
range 9.1-9.3 by adding sodium aluminate solution. The product is a suspension of
glassy precipitate of pseudoboehmite containing 300 g of Al2O3.
To produce boehmite, 1 L of a 100 g/L sodium aluminate
solution is used. The precipitation is performed by simultaneously pouring together
the indicated aluminate solution and a 60% solution of nitric acid (yield: 0.7 L)
at a temperature of 102-105° C (when boiling) and at a pH in the range 8.5
to 8.9 over the course of 2 hours. The product is a suspension of honey-like precipitate
of boehmite containing 100 g of Al2O3.
The resulting suspensions of pseudoboehmite and boehmite
are combined and washed on a Büchner funnel to remove the contaminating sodium
nitrate salt. The washed precipitate is dried at I 10° C for 10 hours and ground
into a fine powder all of which passes through a sieve having 0.25 mm openings.
The calcining loss when the resulting dried mixed aluminum hydroxide powder is roasted
at 850° C is 24.6% by mass. The ratio of boehmite to pseudoboehmite in the
aluminum hydroxide powder is 1:3, calculated on the basis of Al2O3.
After that, the powdered sulfated zirconium hydroxide is
mixed with 83.6 g of powdered aluminum hydroxide in a Werner & Pfleiderer Z blade
mixer, the solution is peptized with sulfuric acid solution (3.8 mL of 60% solution),
and small portions of around 250 mL of water are added, bringing the moisture content
(calcining loss) of the mass to 55% by mass. The resulting mass is molded in a screw
extruder through a die having a hole diameter of 2.0 mm. The extrudates are dried
for 8 hours at 110° C and then roasted in a stream of dried air for 4 hours
at 630° C.
Gross composition of the finished catalyst: 66.2% by mass
of ZrO2; 30% by mass of &ggr;-Al2O3; 5.0% by
mass of S. The total content of aluminum and zirconium sulfate in the catalyst was
15.0% (calculated on the basis of SO4), and the total content of aluminum
oxide and sulfate was 30% by mass (calculated on the basis of Al2O3).
b) Test of Catalyst
The process of alkylating phenol by &agr;-methylstyrene
on the resulting catalyst is carried out at a temperature of 80° C and with
a raw material volume feed rate of 1 h-1.
The raw material used is a mixture of phenol, cumene, and
&agr;-methylstyrene having the composition (in mass %): cumene - 45%; phenol -
45%; and &agr;-methylstyrene - 10%.
The yield of the catalysis product was 99.89%, and its
composition was as follows (in mass %): cumene - 46.68%; &agr;-methylstyrene -
0.05%; phenol - 34.57%; PCP - 16.61; o-cumylphenol - 1.19; and dimers - 0.9%.
After p-cumylphenol is isolated by distillation,
the product has the following composition (in mass %): p-cumylphenol - 98.2%;
o-cumylphenol - 1.4%; dimers - 0.16%; &agr;-methylstyrene and others -
The composition of the catalysis product was determined
by gas/liquid chromatography on a "Kristall 2000M" chromatograph with a capillary
column 25 m long using OV-1 as the stationary phase.
a) Preparation of Catalyst
The catalyst is prepared as in Example 1, but the ratio
of boehmite to pseudoboehmite (calculated on the basis of Al2O3)
in the mixed powdered aluminum hydroxide is 3:1. The zirconium hydroxide precipitate
is sulfated with 380 mL of sulfuric acid solution. The quantity of mixed powdered
aluminum hydroxide taken for mixing with the powdered sulfated zirconium hydroxide
is 13.9 g. The remaining parameters are the same as in Example 1.
The total content of aluminum and zirconium sulfates in
the resulting sample of roasted (finished) catalyst, calculated on the basis of
SO4, was 5.0% by mass, and the total content of aluminum oxide and sulfate
was 5% by mass, calculated on the basis of Al2O3.
b) Test of Catalyst
The resulting catalyst is tested under the conditions of
Example 1 at a temperature of 110° C and a raw material volume feed rate of
3 h-1. The resulting catalysis product has the following composition
(in mass %): cumene - 46.13%; &agr;-methylstyrene ― 0.04%; phenol - 34.6%;
PCP - 17.17%; o-cumylphenol - 1.10%; and dimers - 0.5%.
Thus, the proposed aluminum zirconium catalyst, produced
by the proposed process, makes it possible to carry out the process of synthesizing
p-cumylphenol by alkylation of phenol with &agr;-methylstyrene at a temperature
of 80-110° C and a raw material volume feed rate of 1-3 h-1 with
extremely high efficiency: the content of the end product PCP in the catalysis product
is more than 17% by mass, with a low percentage of side products formed -
o-cumylphenol and dimers up to 2% by mass.
The catalyst worked 500 hours without a noticeable reduction
in its activity or selectivity.