WO2001000560A1

WO2001000560A1 - Process for preparing aromatic carbonates

Info

Publication number: WO2001000560A1
Application number: PCT/KR2000/000687
Authority: WO
Inventors: Jae-Sung Lee; Kwang-Ho Park; Yeong-Dae Kim
Original assignee: Lg Chemical Ltd.
Priority date: 1999-06-29
Filing date: 2000-06-29
Publication date: 2001-01-04

Abstract

The present invention, which relates to a process for preparing aromatic carbonates, provides a process for preparing diphenylcarbonate comprising the steps of preparing methylphenylcarbonate by gas phase reacting or liquid phase reacting dimethylcarbonate with phenol under titanium-silica catalyst in which titanium is supported on silica support and liquid phase reacting the prepared methylphenylcarbonate under titanium-silica catalyst in which titanium is supported on silica support, a process for preparing methylphenylcarbonate by liquid phase reacting dimethylcarbonate with phenol using molybdenum-activated carbon catalyst in which molybdenum is supported on activated carbon, and a process for preparing methylphenylcarbonate by gas phase reacting dimethylcarbonate with phenol using heterogeneous solid catalyst.

Description

PROCESS FOR PREPARING AROMATIC CARBONATES

BACKGROUND OF THE INVENTION

(a) Field of the Invention

The present invention relates to a process for preparing aromatic

carbonates. Specifically, the present invention relates to a process for

synthesizing methylphenylcarbonate using dimethylcarbonate and phenol as

starting materials and a process for synthesizing diphenylcarbonate from

methyphenylcarbonate.

(b) Description of the Related Art

Generally, diphenylcarbonates are synthesized using

dimethylcarbonate and phenol as starting materials, and they are

synthesized through two steps of synthesizing methylphenylcarbonate and

synthesizing diphenylcarbonate. In each step, gas phase reaction and

liquid phase reaction can be used.

Most of researches concerning the above reaction reported liquid

phase reactions. And, Lewis acid, transition metal salt, ester, organic and

inorganic borate, etc. can be use as a catalyst, and particularly,

homogeneous catalysts such as Ti(OX)₄ (wherein, X is alkyl or aryl group)

are known to be effective.

The use of homogeneous catalysts such as tin or titanium compound

is described in an article (Ind. Eng. Chem. Res., 31 , pp. 1 167-1170, 1992). Japanese Patent Publication No. Sho 54-125617 described the use of

heterogeneous catalyst such as a physical mixture of silica-titanium. In

addition, it was reported that Molybdenum oxide supported on silica had

good activity (Pure and Applied Chemistry, 68, Iss. 2, pp. 367-375, 1996).

U.S. Patent No. 5,380,908 described removing by-products, alcohols,

by reaction distillation method comprising continuous processes using

dibutyltin oxide as a catalyst, under atmospheric pressure, reduced pressure

and vacuum condition, at a reaction temperature of 100 to 200 ^°C , in

synthesizing diphenylcarbonates.

In addition, U.S. Patent No. 5,426,207 reported that yield can be

improved by dividing three reaction zones, using organic titanate catalyst

and using multiple stage reactor, and that the cost of reboiler can be reduced

by using vaporization heat to separate mixture. U.S. Patent No. 5,210,268

stated that diphenylcarbonates could be obtained by using Pb compound as

a catalyst and using distillation column having two stages with high reaction

rate, yield and selectivity.

SUMMARY OF THE INVENTION

It is an object of the present invention to provide a process for

preparing diphenylcarbonate through gas phase reaction and liquid phase

reaction using novel silica-supported titanium catalyst with high activity.

It is another object of the present invention to provide a process for

preparing methylphenylcarbonate having high activity by liquid phase reacting dimethylcarbonate and phenol using novel active carbon-supported

molybdenum catalyst.

It is another object of the present invention to provide a process for

preparing methylphenylcarbonate having high activity by gas phase reacting

dimethylcarbonate and phenol using heterogeneous solid catalyst.

DETAILED DESCRIPTION AND THE PREFERRED EMBODIMENTS

In order to achieve these objects, the present invention provides a

process for preparing diphenylcarbonate comprising the steps of preparing

methylphenylcarbonate by gas phase reaction or liquid phase reaction of

dimethylcarbonate and phenol in the presence of catalyst, and preparing

diphenylcarbonate by liquid phase reaction of the obtained

methylphenylcarbonate in the presence of catalyst, wherein said catalyst is a

titanium-silica catalyst comprising 1 to 30 wt% of supported titanium on the

basis of the weight of the catalyst.

The titanium-silica catalyst is prepared by supporting precursor that

is prepared by dissolving titanium compound selected from a group

consisting of Ti(IV)-butoxide, Ti(IV)-ethoxide, Ti(IV)-isopropoxide, and Ti(IV)-

chloride in organic solvent on Si0₂ support by incipient wetness, drying the

supported precursor, and calcinating the dried precursor at a calcination

temperature of 500 to 800 ^°C , preferably 500 to 600 ^°C , for 4 hours.

The process for preparing diphenylcarbonate comprises the steps of;

a) mixing dimethylcarbonate and phenol at a mole ratio of 1 :1 to 10:1 o prepare liquid phase mixture;

b) vaporizing said liquid phase mixture;

c) gas phase reacting said vaporized mixture in continuous flow gas

phase reactor, in the presence of silica catalyst, at a reaction temperature of

300 to 600 "C , preferably 370 to 480 ^°C to prepare methylphenylcarbonate;

d) dissolving said methylphenylcarbonate in hexane solvent; and

e) liquid phase reacting said methylphenylcarbonate in the presence

of titanium-silica catalyst in which titanium is supported on silica support, at a

reaction temperature of 150 to 180 ^°C , under nitrogen pressure of 6 to 8 atm,

with stirring, to prepare diphenylcarbonate.

Another process for preparing diphenylcarbonate comprises the

steps of;

a) mixing dimethylcarbonate and phenol at a mole ratio of 1 : 1 to

10:1 to prepare liquid phase mixture;

b) liquid phase reacting said liquid phase mixture in batch type

liquid reactor, in the presence of titanium-silica catalyst in which titanium is

supported on silica support, at a reaction temperature of 150 to 180 ^°C ,

under nitrogen pressure of 6 to 8 atm, with stirring, to prepare

methylphenylcarbonate;

c) dissolving said methylphenylcarbonate in hexane solvent; and

d) liquid phase reacting said methylphenylcarbonate in the presence

of titanium-silica catalyst n which titanium is supported on silica support, at a reaction temperature of 150 to 180 ^°C, under nitrogen pressure of 6 to 8 atm,

with stirring, to prepare diphenylcarbonate.

The reaction system of the present invention used gas phase reactor

and batch type liquid reactor.

A continuous flow type gas phase reactor uses glass tube made of

pirex or quartz, and therein, methylphenylcarbonate is prepared by

vaporizing the liquid mixture of reactants, dimethylcarbonate and phenol,

heating the vaporized mixture before it reach reactor, and gas phase

reacting the heated mixture in the presence of titanium-silica catalyst.

In batch type liquid reactor, diphenylcarbonate is prepared by diluting

said methylphenylcarbonate in solvent such as heptane and liquid phase

reacting the diluted methylphenylcarbonate in the presence of titanium-silica

catalyst.

The reaction uses a catalyst in which titanium is supported on silica

support. The amount of supported metal is preferably 1 to 30 wt% of

titanium on the basis of total catalyst weight, more preferably 5 to 20 wt%.

Ti(IV)butoxide, Ti(IV) ethoxide, Ti(IV)isopropoxide, Ti(IV)chloride, etc. can be

used as a precursor of titanium.

The silica-supported titanium catalyst is prepared as follows.

Firstly, the titanium precursor is dissolved in organic solvent such as toluene

and heptane (the used solvent is not limited to toluene and heptane) in an

amount of 1 to 30 wt%. The resulting solution is supported on silica support by incipient wetness, and then it is dried in an oven of temperature of 110 ^°C

for 12 hours or more, it is calcinated at 500 to 800 ^°C for 4 hours or more

with flowing air to prepare silica-supported titanium catalyst in which titanium

is uniformly dispersed on silica support.

The resulting catalyst is used in gas phase methylphenylcarbonate

synthesis reaction. In the gas phase methylphenylcarbonate synthesis

reaction, active reaction induction period lasts 0 to 200 minutes due to the

reactivity of dimethylcarbonate itself, and the yield of methylphenylcarbonate

at plateau can be identified by Examples 1 to 19 and Comparative Examples

1 to 3.

The another embodiment of the present invention provides a process

fro preparing methylphenylcarbonate comprising the steps of mixing

dimethylcarbonate and phenol at a mole ratio of 1 :1 to 10:1 to prepare liquid

phase mixture, and liquid phase reacting the prepared mixture in the

presence of active carbon-supported molybdenum catalyst at a reaction

temperature of 150 to 180 ^°C in a batch type liquid phase reactor with

stirring.

The process used batch type liquid phase reactor.

The catalyst used in the process is molybdenum-active carbon

catalyst comprising 1 to 30 wt% of molybdenum metal. The molybdenum-

active carbon catalyst is prepared by dissolving molybdenum precursor,

ammonium heptamolybdate ((NH₄)₆Mo₇0₂₄- 4H₂0) in secondary distilled water in an amount of 1 to 30 wt% of molybdenum metal on the basis of total

catalyst weight to prepare an aqueous solution, supporting the prepared

solution on active carbon, drying the solution in an oven at 110 ^°C for 12

hours or more, heating the solution at 500 to 800 ^°C for 4 hours with

dripping helium.

The molybdenum-active carbon catalyst exists in the form of Mo0₂ in

which active metal phase has oxidation number of 4.

In the liquid phase reaction, reaction pressure of approximately 6.8

atm can be added by charging nitrogen gas. However, the reaction under

atmospheric pressure showed better result.

The effect of the process can be identified in Examples 20 to 23 and Comparative Examples 4.

The another embodiment of the present invention provides a process

for preparing methylphenylcarbonate comprising the steps of;

a) mixing dimethylcarbonate and phenol at a mole ratio of 1 :1 to 10:1

to prepare liquid phase mixture;

b) vaporizing the liquid phase mixture; and

c) gas phase reacting the vaporized mixture in the presence of a

catalyst selected from the group consisting of molybdenum(Mo)-supported

catalyst, titanium(Ti)-supported catalyst, chromium(Cr)-supported catalyst,

tungsten(W)-supported catalyst, vanadium(V)-supported catalyst and tin(Sn)-

supported catalyst, at 300 to 600 ^°C . The Mo-supported catalyst has 1 to 30 wt% of supported Mo metal,

and is prepared by supporting molybdenum oxide precursor, (NH₄)₆Mo₇0₂₄-

4H₂0, on a support selected from a group consisting of aluminium oxide

(Al₂0₃), titanium oxdie (Ti0₂), silicon oxide (Si0₂) and active carbon (C).

The Ti-supported catalyst has 1 to 30 wt% of Ti metal, and is

prepared by supporting titanium oxide precursor selected from a group

consisting of Ti(IV)-butoxide, Ti(IV)-ethoxide, Ti(IV)-isopropoxide and Ti(IV)-

chloride on a support selected from a group consisting of aluminium oxide

(Al₂0₃), magnesium oxide (MgO), silicon oxide (Si0₂) and active carbon (C).

The Cr-supported has 1 to 30 wt% of supported Cr metal, and is

prepared by supporting chromium oxide precursor, chromium nitrate hydrate

(Cr(N0₃)₃- 9H₂0), on a silica (Si0₂) support.

The W-supported catalyst has 1 to 30 wt% of supported W metal,

and is prepared by supporting tungsten oxide precursor, (NH₄)₆W₁₂0₃₉- xH₂0,

on a silica support.

The Sn-supported catalyst has 1 to 30 wt% of supported Sn metal,

and is prepared by supporting tin oxide precursor, SnCI₂, on a silica support.

The process uses glass tube made of pirex or quartz as a continuous

flow type gas phase reactor, and in the glass tube, liquid mixture of reactants,

dimethylcarbonate and phenol, is vaporized by heating before it reach

reactor.

The reaction uses a catalyst in which metal oxides are supported on various supports. The catalyst is a heterogeneous solid catalyst that is

prepared by supporting metal precursor solution on each support by incipient

wetness in an amount of 1 to 30 wt%, drying the solution in an oven of 1 10^°C

for 12 hours or more, calcinating the solution at 500 to 800 ^°C under helium

or air atmosphere.

In all the catalysts as explained, the supported metals exist in the

form of completely oxidated metal oxide, unless differently indicated.

The present invention will now be explained in more detail with

reference to the following Examples and Comparative Examples.

[Example 1]

Ti(IV)-butoxide was dissolved in toluene solvent such that the

amount of titanium reached 10 wt% of total catalyst weight to prepared

titanium precursor solution wherein the amount of total solution

corresponded to the volume of fine pores of silica support. Then, the

solution was supported on silica.

The supported solution was dried in an oven at 1 10 ^°C for 12 hours

or more, and it was then calcinated at 500 ^"C for 4 hours with flowing air to

prepare silica-supported titanium catalyst in which titanium is uniformly

dispersed through the silica support.

As a pretreatment of the catalyst, the catalyst was heat-treated at a

temperature 50 ^°C higher than the reaction temperature for 1 hour with

flowing nitrogen gas only before reaction. In the continuous flow type gas phase reactor, 0.48 g of the catalyst

was used. And, the mixed solution of reactants, dimethylcarbonate and

phenol, of a mole ratio of 5:1 was injected to the reactor in an amount of 1 ml

per hour, nitrogen was dripped as a carrier gas in an amount of 20 ml per

minute so as to smooth the arrival of reactants to catalyst layer, reactants

were vaporized before reaching reactor by heating, and gas phase reacting

dimethylcarbonate with phenol for 90 minutes under these conditions to

prepare methylphenylcarbonate.

In the gas phase reaction, the conversion rate of phenol and the

selectivity and the yield of methylphenylcarbonate according to temperature

are presented in following Table 1.

The conversion rate was based on phenol, the selectivity and the

yield of mlethylphenylcarbonate were calculated from the mass concentration

in materials produced by the conversion of phenol.

[Table 1]

[Example 2]

Methylphenylcarbonate was prepared at 430 ^°C by the same

method as in Example 1 , except that helium was used as a carrier gas

instead of nitrogen. The conversion rate, selectivity and yield are presented

in following Table 2.

[Table 2]

[Example 3]

Methylphenylcarbonate was prepared at 430 "C by the same

method as in Example 1 , with changing flow rate of carrier gas nitrogen from

0 to 70 ml per minute. The conversion rate, selectivity and yield are

presented in following Table 3.

π [Table 3]

[Example 4]

Methylphenylcarbonate was prepared at 430 °C by the same

method as in Example 3, with changing flow rate of mixture of

dimethylcarbonate and phenol. The conversion rate, selectivity and yield

are presented in following Table 4.

[Table 4]

[Examples 5 - 9, Comparative Example 1]

Ti(IV)-butoxide was dissolved in toluene solvent such that the

amount of titanium corresponded to 0, 5, 10, 13, 20, 30 wt% of total catalyst

weight to prepare each titanium precursor solution wherein the amount of

total solution corresponds to the volume of fine pores of silica supportr.

Then, the solution was supported on silica.

Each solution having different supported titanium amount was dried

in an oven at 110 ^°C for 12 hours or more, and it was calcinated at 500 ^°C

for 4 hours to prepare silica-supported titanium catalyst in which titanium is

uniformly dispersed through silica support.

As pretreatment of the catalyst, the catalyst was heat-treated at

480 ^°C that is 50 ^°C higher than reaction temperature for 1 hour with

dipping nitrogen gas only before reaction.

Methylphenylcarbonate was prepared using 0.48 g of the catalyst at

430 ^°C by the same method as in Example 1. The conversion rate,

selectivity and yield are presented in following Table 5. [Table 5]

[Example 10]

Ti(IV)-butoxide was dissolved in toluene solvent such that the

amount of titanium reached 10 wt% of total catalyst weight to prepare

titanium precursor solution wherein the amount of total solution corresponds

to the volume of fine pores of silica. Then, the solution was supported on

silica.

The solution was dried in an oven at 110 ^°C for 12 hours or more, it

was then calcinated at a temperature of 500, 600, 700 and 800 ^°C for 4

hours with dripping air to prepare each silica-supported titanium catalyst in which titanium was uniformly dispersed through the silica support.

As a pretreatment of the catalyst, the catalyst was heat-treated at

480 ^°C that is 50 ^°C higher than reaction temperature for 1 hour before

reaction.

Methylphenylcarbonate was prepared using 0.48 g of the catalyst at

430 ^°C . The conversion rate, selectivity and yield are presented in following

Table 6.

[Table 6]

[Example 11]

Dimethylcarbonate was introduced in a reactor in an amount of 0.85

ml per hour and was suctioned for 90 minutes, instead of heating 0.48 g of

catalyst comprising 10 wt% of supported titanium as a pretreatment in

Example 1.

Mehtylphenylcarbonate was prepared using 0.48 g of the catalyst at a reaction temperature of 430 ^°C by the same method as in Example 1. The

conversion rate, selectivity and yield are presented in following Table 7.

[Table 7]

[Examples 12 - 14]

Ti(IV)-butoxide, Ti(IV)-ethoxide, Ti(IV)-isopropoxide and Ti(IV)-

chloride were respectively dissolved in toluene solvent such that the amount

of titanium reached 10 wt% of total catalyst weight to each prepare titanium

precursor solution wherein the amount of total solution corresponds to the

volume of fine pores of silica support. Then, the solution was supported on

silica.

The solutions were respectively dried in an oven at 110 ^°C for 12

hours or more, and calcinated at 500 ^°C for 4 hours to prepare each silica-

supported titanium catalyst in which titanium is uniformly dispersed through

the silica support. [Table 8]

[Examples 15 - 18]

Ti(IV)-butoxide, Ti(IV)-ethoxide, Ti(IV)-isopropoxide and Ti(IV)-

chloride were respectively dissolved in toluene solvent such that the amount

of titanium reach 10 wt% of total catalyst to prepare each titanium precursor

solution wherein the amount of total solution corresponds to the volume of

fine pores of silica support. Then, each solution was supported on silica

support.

The solutions were respectively dried in an oven at 110 ^°C for 12

hours or more, and calcinated at 500 ^°C foOr 4 hours to prepare each silica-

supported titanium catalyst in which titanium is uniformly dispersed through the silica support.

Methylphenylcarbonate was prepared by introducing each catalyst in

batch type liquid phase reactor in an amount of 1 g, dissolving 595 mmol of

dimethylcarbonate and 119 mmol of phenol in 80 ml of n-hexane and

introducing it in the reactor, and conducting liquid phase reaction at 160 ^°C ,

under nitrogen pressure of 6.8 atm, with stirring at a rate of 400 rpm.

The selectivity and yield of methylphenylcarbonate 1 and 4 hours

after the liquid phase reaction were presented in following Table 9.

[Comparative Example 2]

Ammonium heptamolybdate ((NH4)6Mo7024 - 4H20) was dissolved

in secondary distilled water such that the amount of molybdenum reached 20

wt% of total catalyst weight to prepare molybdenum precursor solution

wherein the amount total solution corresponds to the volume of fine pores of

silica support. Then, the solution was supported on silica.

The solution was dried in an oven at 110 ^°C for 12 hours or more,

and calcinated at 500 ^°C for 4 hours with dripping air to prepare silica-

supported molybdenum catalyst in which molybdenum is uniformly dispersed

through the silica support.

Methlphenylcarbonate was prepared by conducting liquid phase

reaction using said molybdenum catalyst by the same method as in Example

15.

The selectivity and yield of methylphenylcarbonate 1 and 4 hours after the liquid phase reaction are presented in following Table 9.

[Table 9]

[Example 19]

Diphenylcarbonate was prepared by introducing 0.5 g of the catalyst

comprising 10 wt% of supported titanium prepared in Example 1 in batch

5 type liquid phase reactor, dissolving 31.2 mmol of methylphenylcarbonate

having purity of 94.3 % (containing 5.7 wt% of phenol as impurities) in 80 ml

of n-hexane solvent to introduce it in the reactor, and conducting liquid phase

reaction at 160 ^°C , under nitrogen-charged reaction pressure of 6.8 atm,

with stirring at a rate of 400 rpm.

io The selectivity and yield of diphenylcarbonate are presented in

following Table 10.

[Comparative Example 3]

Diphenylcarbonate was prepared using 0.5 g of molybdenym-silica

catalyst prepared in Comparative Example 2 by conducting liquid phase

15 reaction as in Example 19.

The selectivity and yield of diphenylcarbonate are presented in

following Table 10. [Table 10]

[Example 20]

Methylphenylcarbonate was prepared by reacting 476 mmol of

dimethylcarbonate and 95.9 mmol of phenol in the presence of 2 g of molybdenum-active carbon catalyst comprising 20 wt% of molybdenum

metal, at 160 ^°C , at a stirring rate of 400 rpm, without adding external

pressure, in a batch type liquid phase reactor.

The activities of methylphenyl carbonate are presented in following

Table 11. The selectivity and yield are calculated from mass concentration

of methylphenylcarbonate in materials produced from the conversion of

phenol.

[Comparative Example 4]

Methylphenylcarbonate was prepared by the same method as in

Example 20, except that silica was used as a supportr instead of active

carbon and the amount of supported molybdenum metal was 10 wt%.

The activities of the methylphenylcarbonate are presented in

following Table 11.

[Table 11]

[Example 21]

Methylphenylcarbonate was prepared by the same method as in

Example 2, except that the reactor was filled with nitrogen gas of 6.8 atm,

and 714 mmol of dimethylcarbonate and 142.8 mmol of phenol were used as

reactants. The results are presented in following Table 12.

[Example 22]

Methylphenylcarbonate was prepared by the same method as in

Example 21 , except that the temperature was lowered to 75 ^°C at a reaction

time of 4 hours, produced methanol was removed by nitrogen gas for 10

minutes, and reaction was continued at a reaction temperature of 160 ^°C ,

under reaction pressure of 6.8 atm. The results are presented in following

Table 12.

The activities of methyphenylcarbonate increased by removing

methanol. [Table 12]

[Example 23]

Methylphenylcarbonate was prepared by the same method as in

Example 21 , except that the reaction time increased to 70 hours.

The results are presented in the following Table 13.

The production of anisole (C₆H₅OCH₃) rapidly increased from the

reaction time of 10 hours. [Table 13]

[Preparative Examples 1 - 15]

Heterogeneous solid catalysts were prepared by supporting

molybdenum(Mo), chromium (Cr), tungsten (W), vanadium (V), tin (Sn),

titanium (Ti) metal precursor solutions on a support selected from aluminium

oxide (Al₂0₃), titanium oxide (Ti0₂), Si0₂ (silicon oxide) and C (active carbon) by incipient wetness, heat-treating the solutions at 500 ^°C , for 4 hours with

dripping air or helium gas. The kinds of solvents, precursor solutions and

heat treatment gases used in each preparative example are presented in

Table 14.

The catalysts were heat-treated at a temperature 50 ^°C higher than

reaction temperature for 1 hour with dripping nitrogen gas before reaction,

and they were used in preparing methylphenylcarbonate by reacting

dimethylcarbonate and phenol.

[Preparative Example 16]

MoN-C catalyst was prepared by heat-treating Mo(IV)-C catalyst of

preparative example 4 at 700 ^°C for 1 hour with dripping ammonia gas.

[Preparative Example 17]

Mo₂C-C catalyst was prepared by heat-treating MoN-C catalyst of

preparative example16 at 700 ^°C for 1 hour with dripping methane and

hydrogen at a ratio of 1 :4.

[Table 14]

[Examples 24 - 29]

Mo-Si0₂ catalyst of Preparative Example 1 was used as a reaction catalyst, a mixed solution of reactants, dimethylcarbonate and phenol, of a

ratio of 5:1 was introduced in continuous flow type reactor at a rate of 1 ml/hr

and reaction was conducted with changing the reaction temperature from

300 to 600 ^°C . Nitrogen was used as a carrier gas and a flow rate thereof

is 20 ml/min. And, reactants were all vaporized through heating before

reaching the reactor in order to smooth the arrival of reactants to catalyst

layer.

The conversion rate of phenol and the selectivity and yield of

phenylcarbonate according to each catalyst at a reaction time of 500 minutes are presented in Table 15.

The conversion rate of phenol is based on the weight of phenol, and

the selectivity and yield of methylphenylcarbonate are calculated from the

mass concentration thereof in the products produced by the conversion of

phenol.

[Table 15]

[Examples 30-34]

Methylphenylcarbonate was prepared by the same method as in

Example 24, except that the amount of Mo-Si0₂ catalyst of Preparative

Example 1 was 1 g, the reaction temperature was fixed to 450 ^°C , with

changing the mole ratio and flow rate of reactants.

The results are presented in Table 16.

[Table 16]

[Examples 35-39, Comparative Example 5]

Methylphenylcarbonate was prepared by the same method as in

Example 24, except that a flow rate of nitrogen was 30 ml/min, and the

reaction temperature was fixed to 450 ^°C , with changing the amount of

supported metal in Mo-Si0₂ catalyst of Preparative Example 1..

The results are presented in Table 17. [Table 17]

[Examples 40-44, Comparative Example 6]

Methylphenylcarbonate was prepared by the same method as in

Example 24, except that the reaction temperature was fixed to 450 ^°C , with

changing the amount of supported metal in Mo(IV)-C catalyst of preparative

example 4. The results are presented in Table 18.

[Table 18]

[Examples 44-48, Comparative Example 7]

Methylphenylcarbonate was prepared by the same method as in

Example 24, except that Mo(IV)-C catalyst of Preparative Example 4 was used, and reaction temperature was fixed to 450 °C , with changing flow rate

of nitrogen.

The results are presented in Table 19.

[Table 19]

[Examples 49-54]

Methylphenylcarbonate was prepared by the same method as in

Example 24, except that Mo(IV)-C catalyst of Preparative Example 4 was

used, and reaction temperature was fixed to 450 ^°C , and flow rate of

nitrogen was fixed to 30 ml/min, with changing flow rate of reactants.

The results are presented in Table 20. [Table 20]

[Examples 55-61]

Methylphenylcarbonate was prepared by the same method as in

Example 24, except that Ti-Si0₂ catalyst was used, with changing reaction

temperature. The results are presented in Table 21. [Table 21]

[Examples 62-66, Comparative Example 8]

Methylphenylcarbonate was prepared by the same method as in

Example 1 , except that reaction temperature was fixed to 430 ^°C , with

changing the amount of supported metal in Ti-Si0₂ catalyst of Preparative

Example 12.

The results are presented in Table 22.

[Table 22]

[Examples 67-83]

The catalysts of Preparative Examples 1 to 17 were used, a mixed

solution of dimethylcarbonate and phenol of a mole ratio of 5:1 was

introduced in the reactor at a rate of 1 ml/hr, nitrogen was dripped at a rate of

20 ml/min as a carrier gas, and the reactants were vaporized through heating

before reaching the reactor so as to smooth the arrival of reactants to

catalyst layer. Each catalyst was heat-treated at 500 ^°C for 1 hour with

dripping nitrogen gas, and then reaction temperature was fixed to 450 ^°C

and reaction was conducted for 500 minutes.

The activities of methylphenylcarbonate prepared by gas phase

reaction of dimethylcarbonate and phenol are presented in Table 23.

[Table 23]

Accordign to the process for preparing diphenylcarbonate of the

present invention comprising the steps of conducting gas phase reaction or

liquid phase reaction of dimethylcarbonate and phenol in the presence of titanium-silica catalyst in which titanium is supported on silica support to

prepare methylphenylcarbonate, and conducting liquid phase reaction of the

prepared methylphenylcarbonate in the presence of titanium-silica catalyst in

which titanium is supported on silica suppot, the selectivity and yield of

methylphenylcarbonate or dkphenylcarbonate are high, and thus

methylphenylcarbonate or diphenylcarbonate can be prepared with high

productivity.

In addition, according to the process for preparing

methylphenylcarbonate by liquid phase reaction of dimethylkcarbonate and

phenol using active carbon-supported molybdenum catalyst, the selectivity

and yield of methylphenylcarbonate are high and thus

methylphenylcarbonate can be prepared with high productivity.

In addition, according to the process for preparing

methylphenylcarbonate by gas phase reaction of dimethylcarbonate and

phenol using solid catalyst, the selectivity and yield of

methylphenylcarbonate are high and thus methylphenylcarbonate can be

prepared with higher productivity, compared to the conventional process

using liquid phase reaction.

Claims

WHAT IS CLAIMED IS:

1. A process for preparing diphenylcarbonate comprising the steps of gas

phase or liquid phase reacting dimethylcarbonate with phenol in the

presence of catalyst to prepare methylphenylcarbonate, and liquid phase

reacting the prepared methylphenylcarbonate in the presence of a catalyst to

prepare diphenylcarbonate, wherein said catalyst is a titanium(Ti)-silica

catalyst comprising 1 to 30 wt% of supported Ti metal on the basis of

catalyst weight,

2. The process for preparing diphenylcarbonate according to claim 1 ,

wherein said Ti-silica catalyst comprises 5 to 20 wt% of supported Ti on the

basis of catalyst weight.

3. The process for preparing diphenylcarbonate according to claim 1 ,

wherein said Ti-silica catalyst is prepared by dissolving a Ti compound

selected from a group consisting of Ti(IV)-butoxide, Ti(IV)-ethoxide, Ti(IV)-

isopropoxide and Ti(IV)-chloride in organic solvent to prepare a precursor,

supporting the precursor on Si0₂ carrier, drying the supported precursor, and

calcinating the supported precursor at a calcination temperature of 500 to

800 ^°C for 4 hours.

4. The process for preparing diphenylcarbonate according to claim 1 ,

wherein said calcination temperature is 500 to 600 ^°C .

5. A process for preparing diphenylcarbonate comprising the steps of; a) mixing dimethylcarbonate and phenol at a mole ratio of 1 :1 to 10:1 to

prepare liquid phase mixture;

b) vaporzing said liquid phase mixture;

c) gas phase reacting said vaporized liquid mixture at a reaction

temperature of 300 to 600 ^°C , in the presence of Ti-silica catalyst, in a

continuous flow type gas phase reactor to prepare methylphenylcarbonate;

d) dissolving said methylphenylcarbonate in hexane solvent; and

e) liquid phase reacting said dissolved methylphenylcarbonate in the

presence of Ti-silica catalyst in which titanium is supported on silica support,

at a reaction temperature of 150 to 180 ^°C , under nitrogen pressure of 6 to 8

atm, with stirring, to prepare diphenylcarbonate.

6. The process for preparing diphenylcarbonate according to claim 5,

wherein in step c), the reaction temperature is 370 to 480 ^°C .

7. A process for preparing diphenylcarbonate comprising the steps of;

a) mixing dimethylcarbonate and phenol in a mole ratio of 1 :1 to 10:1 to

prepare liquid phase mixture;

b) liquid phase reacting the liquid phase mixture in batch type liquid

phase reactor, in the presence of titanium-silica catalyst in which titanium

metal is supported on silica support, at a reaction temperature of 150 to

180 "C , under nitrogen pressure of 6 to 8 atm, with stirring, to prepare

methylphenylcarbonate;

c) dissolving the prepared methylphenylcarbonate in hexane solvent; and

d) liquid phase reacting the dissolved methylphenclarbonate in the

presence of titanium-silica catalyst in which titanium is supported on silica

support, at a temperature of 150 to 180 ^°C , under nitrogen pressure of 6 to 8

atm, with stirring, to prepare diphenylcarbonate.

8. A process for preparing methylphenylcarbonate comprising the steps of

a) mixing dimethylcarbonate and phenol in a mole ratio of 1 :1 to 10:1

to prepare liquid phase mixture; and

b) liquid phase reacting the prepared mixture in a batch type liquid

phase reactor, in the presence of a active carbon-supported molybdenum

catalyst, at reaction temperature of 150 to 180 ^°C with stirring to prepare

methylphenylcarbonate.

9. The process for preparing methylphenylcarbonate according to claim 8,

wherein said active carbon-supported molybdenum catalyst (nolybdenum-

active carbon catalyst) comprises 1 to 30 wt% of supported molybdenum

metal on the basis of a weight of catalyst.

10. The process for preparing methylphenylcarbonate according to claim 8,

wherein said wherein said active carbon-supported molybdenum catalyst

(nolybdenum-active carbon catalyst) is prepared by supporting an aqueous

solution that is a heterogeneous catalyst that is prepared by dissolving

molybdenum precursor, ammonium heptamolybdate ((NH₄)₆Mo₇0₂₄- 4H₂0),

in secondary distilled water in an amount of 1 to 30 wt% of total catalyst weight on the basis of molybdenum metal, drying the supported solution in

an oven at 110 ^°C for 12 hours or more, and heat-treating the dried solution

under helium atmosphere at 500 to 800 ^°C for 4 hours or more.

11. The process for methylphenylcarbonate according to claim 8, wherein

the molybdenum metal in said molybdenum-active carbon catalyst comprises

molybdenum oxide having oxide number of 4 (Mo0₂).

12. A process for preparing methylphenylcarbonate comprising the steps

of; a) mixing dimethylcarbonate and phenol in a mole ratio of 1 :1 to 10:1

to prepare liquid phase mixture;

b) vaporizing the liquid phase mixture; and

c) gas phase reacting the vaporized mixture in the presence of a

catalyst selected from a group consisting of molybdenum(Mo)-supported

catalyst, titanium(Ti)-supported catalyst, chromium(Cr)-supported catalyst,

tungsten(W)-supported catalyst, vanadium(V)-supported catalyst and tin(Sn)-

supported catalyst, at a temperature of 300 to 600 ^°C to prepare

methylphenylcarbonate.

13. The process for preparing methylphenylcarbonate according to claim

12, wherein said molybdenum(Mo)-supported catalyst is prepared by

supporting molybdenum oxide precursor, ammoniumheptamolybdate

((NH₄)₆Mo₇0₂₄- 4H₂0), on a support selected from the group consisting of

aluminium oxide (Al₂0₃), titanium oxide (Ti0₂), silicone oxid (Si0₂) and active carbon (C), drying the supported precursor, and calcinating the dried

precursor under air or helium atmosphere at a calcinations temperature of

500 to 800 ^°C for 4 hours or more, and it comprises 1 to 30 wt% of

supported molybdenum metal.

14. The process for preparing methylphenylcarbonate according to claim

12, wherein said titanium(Ti)-supported catalyst is prepared by supporting

titanium oxide precursor selected from a group consisting of Ti(IV)-butoxide,

Ti(IV)-ethoxide, Ti(IV)-isopropoxide and Ti(IV)-chloride on a support selected

from a group consisting of aluminium oxide (Al₂0₃), magnesium oxide (MgO),

silica (Si0₂) and active carbon (C), drying the supported precursor, and

calcinating the dried precursor under air or helium atmosphere at a

calcination temperature of 500 to 800 ^°C for 4 hours or more, and it

comprisese 1 to 30 wt% of supported titanium.

15. The process for preparing methylphenylcarbonate according to claim

12, wherein said chromium(Cr)-supported catalyst is prepared by supporting

a chromium oxide precursor, chromium nitrate hydrate (Cr(N0₃)₃- 9H₂0) on

a silica (Si0₂) support, drying the supported precursor, and calcinating the

dried precursor under air or helium atmosphere at a calcination temperature

of 500 to 800 ^°C for 4 hours or more, and it comprises 1 to 30 wt% of

supported chromium metal.

16. The process for preparing methylphenylcarbonate according to claim

12, wherein said tungsten (W)-supported catalyst is prepared by supporting tungsten oxide precursor, ammonium metatungstate hydrate

'

xH₂0), on a silica (Si0₂) support, drying the supported precursor, and

calcinating the dried precursor under air or helium atmosphere at a

calcination temperature of 500 to 800 ^°C for 4 hours or more, and it

comprises 1 to 30 wt% of supported tungsten metal.

17. The process for preparing mehtylphenylcarbonate according to claim

12, wherein said vanadium(V)-supported catalyst is prepared by supporting

vanadium oxide precursor, ammonium metavanadate (NH₄V0₃), on a silica

(Si0₂) support, drying the supported precursor, and calcinating the dried

precursor under air or helium gas atmosphere at a calcination temperature of

500 to 800 ^°C for 4 hours or more, and it comprises 1 to 30 wt% of

supported vanadium metal.

18. The process for preparing methylphenylcarbonate according to claim

12, wherein said tin(Sn)-supported catalyst is prepared by supporting tin

precursor, tin chloride (SnCI₂) on a silica (Si0₂) support, drying the supported

precursor and calcinating the dried precursor under air or helium gas

atmosphere at a calcination temperature of 500 to 800 ^°C for 4 hours or

more, and it comprises 1 to 30 wt% of supported tin metal.