JPS6316367B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for dehydrogenating ethylphenols to produce the corresponding ethenylphenols.

Conventionally, methods for dehydrogenating alkanes and aromatic hydrocarbons having alkyl side chains to obtain corresponding unsaturated compounds, and methods for producing dienes by dehydrogenating alkenes have been widely studied, and there are many studies on these reactions. Many effective catalysts have also been discovered and are widely used industrially. Further, among these catalysts, it is well known that catalysts composed mainly of chromium oxide, iron oxide, γ-alumina, copper oxide in combination with magnesium oxide, potassium oxide, etc. have excellent performance. However, since ethylphenols have an active phenolic hydroxyl group in their molecules, their reactivity is significantly different from that of alkylbenzenes such as ethylbenzene (Journal of Applied Chemistry, 7).
Vol., pp. 172-182, April 1975; Chemical Abstracts, Vol. 70, 28534w; Asakura Shoten Publishing "Big Organic Chemistry" Vol. 14, p. 83; Chemical Abstracts, Vol. 64, 15039g), the above hydrocarbons Even if the dehydrogenation catalyst is applied to the dehydrogenation of ethylphenols,
Undesirable side reactions such as isomerization, disproportionation, dealkylation, decomposition, dehydration condensation, coking on the catalyst surface, and polymerization of the dehydrogenation product proceed significantly, leading to a reduction in the reaction to the desired ethenylphenol. Low selectivity and poor practicality. Therefore, in order to dehydrogenate alkylphenols and produce ethenylphenol with high selectivity, it is necessary to use a catalyst that is different from the conventionally known catalysts that are effective for dehydrogenating aliphatic hydrocarbons and aromatic hydrocarbons. The development of catalysts with unique performance is strongly desired.

The present inventors have conducted various studies on catalysts for the dehydrogenation reaction of ethylphenols, and have found that titanium oxide or titanium oxide is combined with one or more metal oxides selected from the group consisting of manganese oxide, iron oxide, and tin oxide. A catalyst that combines cerium oxide and calcium oxide has extremely excellent performance in the production of ethenylphenols by dehydrogenating ethylphenols, and can stably maintain high activity and high selectivity for a long time. They discovered this and completed the present invention. That is, the gist of the present invention is to provide a method for producing ethenylphenols by dehydrogenating ethylphenols, in which titanium oxide or titanium oxide is combined with a compound selected from the group consisting of manganese oxide, iron oxide, and tin oxide. The present invention relates to a method for producing ethenylphenols, which is characterized by using a catalyst consisting of more than one type of metal oxide or a combination of cerium oxide and calcium oxide.

The method for preparing the titanium oxide catalyst used in the present invention includes, for example, organic salts such as titanium oxalate and titanium acetate, organic titanium compounds such as alkyl titanium and alkoxy titanium, or titanium hydroxides, carbonates, and nitrates. , a method of heating and baking various inorganic salts such as halides, a method of filtering and washing the precipitate resulting from hydrolysis of titanium tetrachloride, titanium nitrate (), titanium sulfate () or titanium () salt solution, followed by drying and firing, etc. Although there are various methods, any method may be used without being restricted to these examples, and commercially available titanium oxide (2) may be used as is. The titanium oxide (2) obtained by these methods can be used as a catalyst as it is by adjusting the particle size to an appropriate size, or can be used after being compressed into tablets or extruded.

Furthermore, when combining the metal oxides with titanium oxide (), mixing methods, dipping methods, coprecipitation methods,
It may be prepared by any other known method,
For example, methods include mixing titanium oxide (2) with these metal oxides as they are and molding them, or adding titanium oxide (2) in an aqueous solution of various inorganic or organic salts such as halides, carbonates, sulfates, and nitrates of these metals. In addition, a base such as ammonia is added to this, and the resulting precipitate is dried and calcined.An aqueous solution of various inorganic or organic salts of titanium is mixed with an aqueous solution of the metal salt to be combined, and aqueous ammonia is added. Examples include methods of drying and calcining the precipitate. The catalyst obtained in this way can be used in the reaction by pulverizing it to an appropriate particle size, just as in the case of titanium oxide () alone.
Alternatively, it can also be used by extrusion or tablet molding. Further, the blending ratio of titanium oxide and these metal oxides is not particularly limited, but the atomic ratio of titanium/metal is preferably in the range of 0.01 to 100, particularly 0.1 to 10.

In addition, although it is not generally necessary to use a carrier for the catalyst used in the method of the present invention, it may be used in combination with a carrier if necessary, such as when particularly high mechanical strength is required. . In this case, it is necessary to use an inert carrier such as α-alumina, silicon carbide, or diatomaceous earth; use of an active carrier such as γ-alumina or silica may cause side effects such as carbon precipitation. This is not preferred because it increases the reaction.

Next, in the present invention, ethylphenols which are reaction raw materials are ethylphenols having an ethyl group at the ortho, meta or para position relative to the phenolic hydroxyl group, and 1 to 4 aromatic nuclei of these ethylphenols. It means a compound in which the hydrogen atom of is substituted with a methyl group or a methoxy group, or a compound in which one of the hydrogen atoms bonded to the alpha atom of the ethyl group of the above compound is substituted with a methyl group.

According to the present invention, by bringing these ethylphenols into contact with the catalyst at high temperature, the corresponding ethenylphenols can be produced with high selectivity, and the activity remains for a long time.

The reaction temperature is generally between 400 and 700°C, preferably in the range of 500 and 630°C. The feed rate of the raw material ethylphenol to the catalyst layer is usually in the range of 0.1 to 10 hr ^-1 expressed in liquid hourly space velocity (LHSV). The reaction pressure may be normal pressure, reduced pressure, or increased pressure, but it is practical to carry out the reaction under normal pressure to slightly reduced pressure. Equilibrium-wise, the dehydrogenation reaction is easier to proceed under reduced pressure, but from an industrial perspective, slightly elevated pressure is more advantageous in equipment construction and operation, so lowering the partial pressure is sufficient to achieve the desired goal. Also good. In this case, the reaction is usually carried out in the presence of a diluent, and carbon dioxide gas, nitrogen, water vapor, etc. can be used as the diluent, but in general, carbon precipitation is suppressed,
It is also preferred to use steam or a mixture of steam and nitrogen, which has the effect of supplying part of the heat of reaction. The molar ratio of the diluent and ethylphenol introduced into the reaction system is usually 2 to 200, especially 2 to 100.
The range is adopted. The catalyst bed used may be of any type, such as a fixed bed, moving bed, or fluidized bed.

The method of the present invention will be specifically explained below with reference to Examples and Comparative Examples.

Example 1 Titanium oxide manufactured by Catalysts and Chemicals (surface area: 79
m ² /g, pore volume 0.43cc/g, cylindrical shape 1mmφx10
Fill 10ml of mm) into a quartz reaction tube and set the reaction temperature at
Paraethylphenol at 580℃, LHSV1.0hr ^-1
The reaction was carried out for approximately 2 hours by supplying water in a 10-fold molar amount. Gas chromatography of the reactants,
As a result of analysis by gel permeation chromatography and Karl Fischer, the conversion rate of para-ethyl phenol was 40.3%, the selectivity of the reaction product was 88.4% for para-ethyl phenol, 2.1% for para-ethyl phenol dimer, 3 amounts. Oligomer 3.7 over body
%, phenols such as phenol and para-cresol were 2.7%, and decomposition products and others were 3.1%. Next, using this catalyst, dehydrogenation reaction (580℃, 4 hours) and combustion regeneration (550-600℃, 3 hours) were repeated more than 10 times, and the conversion rate of para-ethylphenol was 33-40%. A value of 90 to 95% was consistently obtained for the selectivity of the reaction products in total for paraethenylphenol and its dimer or higher oligomers.

Comparative Example 1 Using 10 g each of a chromium oxide-activated γ-alumina combination catalyst (catalyst A) and an iron oxide-chromium oxide-potassium oxide combination catalyst (catalyst B), the reaction temperature was 580°C in the same manner as in Example 1.
As a result of performing the dehydrogenation reaction of para-ethylphenol for 2 hours at LHSV1.0hr ^-1 and a molar ratio of water and para-ethylphenol of 10, the conversion rate of para-ethylphenol was 43.0% for catalyst A and 19.0% for catalyst B.
The selectivity of the reaction products is 43.2% and 45.9% for paraethenylphenol, 17.6% and 0% for dimer or higher oligomers of paraethenylphenol, and phenols such as phenol and paracresol. were 18.9% and 47.1%, respectively, and decomposition products and others were 20.3% and 12.7%, respectively.

All of these catalysts are commercially available products, and are famous as dehydrogenation catalysts for hydrocarbons such as ethylbenzene and are widely used industrially. When used in a reaction, as shown in the above results, it is clear that the performance is significantly worse than that of a titanium oxide catalyst.

Comparative Example 2 A chromium oxide-nickel oxide combination catalyst (catalyst C) in which the chromium to nickel atomic ratio is 1:1 and a chromium oxide-silica combination catalyst (catalyst D) in which the chromium to silicon atomic ratio is 1:1. The dehydrogenation reaction of para-ethylphenol was carried out under the same conditions as in Comparative Example 1 using 10 g of each. As a result, the conversion rates of para-ethylphenol were 31.1% and 8.7%, respectively, and the selectivity of the reaction product was as follows. Paraethenylphenol 26.1% and 12.4 respectively
%, para-ethenylphenol dimer or higher oligomers were 26.7% and 36.4%, respectively, phenols and phenols such as para-cresol were 10.2% and 25.5%, respectively, and decomposition products and others were 37.0% and 25.7%, respectively. .

Example 2 When the same operation as in Example 1 was performed on a 100 times scale, that is, a stainless steel reactor was charged with a catalyst amount of 1, no difference was observed due to the increase in the size of the experimental device. The conversion rate of paraethylphenol was 40%, and the selectivity for the total of the reaction product paraethylphenol and its oligomer was 93%.

Example 3 An experiment was carried out in the same manner as in Example 1 except that the reaction time was 10 hours. As a result, the conversion rate of para-ethyl phenol was 38%, and the total selectivity of para-ethyl phenol and its oligomer was 94. It was %.
This result shows that the titanium oxide catalyst maintains its activity for a long time in continuous reactions.

Example 4 A catalyst in which 30% by weight of manganese dioxide was supported on the same cylindrical titanium oxide () as used in Example 1 by a normal immersion method was used, and the reaction temperature was 620°C.
As a result of carrying out the reaction for 2 hours in the same manner as in Example 1 at LHSV1.0hr ^-1 and a molar ratio of water and paraethylphenol of 10, the conversion rate of paraethylphenol was
60.1%, and the selectivity of the reaction products is paraethenylphenol 83.1%, paraethenylphenol dimer 2.0%, trimer or higher oligomer 4.8%,
Phenols such as phenol and para-cresol accounted for 7.3%, and decomposition products and others accounted for 2.8%.

Example 5 In Example 4, an experiment was conducted in the same manner as in Example 4 using a catalyst carrying 30% by weight of ferric oxide instead of manganese dioxide. As a result, the conversion rate of para-ethylphenol was 44.8. %, and the selectivity of the reaction product is paraethenylphenol 90.3
%, dimer of paraethenylphenol 1.1%, 3
The amount was 2.5% of oligomers or more, 3.0% of phenols such as phenol and para-cresol, and 3.1% of decomposition products and others.

Example 6 Using the same catalyst as used in Example 1, in which 30% by weight of tin oxide () was supported on titanium oxide (), a reaction temperature of 550°C, LHSV of 1.0 hr ^-1 , and a reaction mixture of water and para-ethylphenol was carried out. As a result of carrying out the reaction for 2 hours in the same manner as in Example 1 at a molar ratio of 10,
The conversion rate of paraethylphenol was 40.9%,
The selectivity of the reaction product is paraethenylphenol
91.1%, paraethenylphenol dimer 0.5%,
Oligomers of trimer or higher were 3.3%, phenols such as phenol and para-cresol were 2.6%, and decomposition products and others were 2.5%.

Example 7 In Example 4, an experiment was conducted in the same manner as in Example 4, using catalysts carrying 10% by weight and 15% by weight of cerium oxide and calcium oxide, respectively, instead of manganese dioxide. The conversion rate of phenol was 56.3%, and the selectivity of the reaction products was 88.5% for paraethenylphenol, 0.5% for paraethenylphenol dimer, 0% for trimer or higher oligomers, and phenol and paracresol. Phenols 8.4% and other decomposition products 2.6
It was %.

Claims (1)

[Scope of Claims] 1. A method for producing ethenylphenols by dehydrogenating ethylphenols to produce corresponding ethenylphenols, the method comprising using titanium oxide () as a catalyst. 2. In a method of dehydrogenating ethylphenols to produce corresponding ethenylphenols, titanium oxide () is combined with one or more metal oxides selected from the group consisting of manganese oxide, iron oxide, and tin oxide, or A method for producing ethenylphenols, characterized by using a catalyst combining cerium oxide and calcium oxide.