JPS61143332A - Synthesis of oxygen-containing compound - Google Patents

Abstract

PURPOSE:To carry out the reaction for the production of acetic acid, acetaldehyde, etc. from synthetic gas in the presence of a Rh-based catalyst, by heating the reaction system close to the reaction temperature in the presence of an inert gas, switching the feed of the inert gas to the synthetic gas used as the raw material, and carrying out the reaction under pressure. CONSTITUTION:In the production of acetic acid, acetaldehyde and ethanol from a synthetic gas in the presence of an Rh-based catalyst, the reaction system is heated to a temperature lower than the reaction temperature by 0-100 deg.C in the presence of an inert gas, and thereafter, the reaction is carried out at 150-450 deg.C under 1-300 atm (preferably at 250-300 deg.C under 20-200 atm) after substituting the inert gas with the synthetic gas used as the raw material. The reaction can be started in an extremely short time at the prescribed reaction temperature without lowering the catalytic activity, and at the same time, the life and the selectivity of the catalyst can be improved. The reaction system is heated quickly to the prescribed reaction temperature by the generation of the heat of reaction when the feed of the inert gas is switched to the synthetic gas.

Description

DETAILED DESCRIPTION OF THE INVENTION (Technical Field of the Invention) The present invention relates to a method for synthesizing oxygen-containing compounds from synthesis gas.

Currently, in the petrochemical industry, the so-called so-called synthesis of heavy oil or petroleum substitutes, oxygenated compounds such as acetic acid, and hydrocarbons such as methane, ethylene, and propylene is taking advantage of the high naphtha price. Research on C chemistry is underway.

As part of 2nd class C chemistry, the present invention deals with the production of so-called C oxygenated compounds such as ethanol, acetaldehyde, and acetic acid from synthesis gas.
In particular, it concerns the direct synthesis of acetic acid.

DESCRIPTION OF THE PRIOR ART Methods for producing carbon@2 oxygenated hydrocarbons, such as acetic acid, acetaldehyde, and ethanol, from synthesis gas, essentially the carbon monoxide and hydrogen contained therein, are known. Rhodium (Rh) is an effective catalyst for this reaction.When a catalytic reaction is carried out, the reaction products vary widely depending on the catalyst used and the reaction conditions.For example, the reaction products range from methane to paraffin wax. various saturated and α-olefin-rich unsaturated aliphatic hydrocarbons, as well as aromatic hydrocarbons with a carbon number of 6 to 10,
Various alcohols ranging from methanol to higher alcohols having nearly 20 carbon atoms, as well as various oxygen-containing hydrocarbon compounds such as aldehydes and fatty acids are produced. In other words, it is extremely difficult to suppress the production of unnecessary compounds and selectively produce only the desired specific compounds from among these vast numbers of various products, and therefore the search for suitable catalysts is required. Various efforts have been made mainly for the above-mentioned acetic acid,
However, when the reaction is carried out under conditions using a rhodium catalyst, such as acetaldehyde or ethanol,
It is true that the formation of undesirable by-products such as carbon gas, methane, and other hydrocarbons is suppressed, and if acetic acid is desired as a target acid-containing compound having 2 carbon atoms selectively, the yield of the target product is sufficient. The problem is that there is no. In particular, since rhodium is an expensive substance, improving its catalytic activity and target product selectivity has important industrial significance.

Research has been conducted on improving carbon monoxide utilization, selectivity, and space-time yield by adding cocatalysts of other components, and research into multicomponent catalysts with rhodium as the main component is progressing further. Various reports have been made regarding rhodium catalysts using various elements as promoters.

It is also disclosed that in order to obtain high selectivity, a rhodium catalyst is used in a low reduction state to improve catalytic activity and selectivity.
Furthermore, according to Japanese Patent Application Laid-Open No. 54-141705, when starting the reaction, while flowing the raw material synthesis gas, the temperature was very gradually increased to 10°C per hour until a predetermined conversion rate was obtained.
Also disclosed is a method of increasing the selectivity by raising the temperature by increasing the temperature as described below.

The present invention aims to improve selectivity by improving the reaction conditions mentioned above, but the former requires that magnesium is used as a cocatalyst and that magnesium is always present together with the alkyl halide in the reaction system. Therefore, it is necessary to add such compounds to the reaction system continuously or intermittently, and complicated equipment such as addition equipment is required. In the latter method, the temperature is raised to the reaction temperature at 10° C. or less for 1 hour in order to improve the selectivity for acetic acid production, but this is not preferable because it takes a long time to start the device.

(Simplified explanation of the invention) Here, the present inventor uses a rhodium-based catalyst to
In synthesizing a combined oxygen compound, when heating the catalyst to the reaction temperature under pressure if necessary, the gas is heated to a temperature close to the predetermined reaction temperature to bring about the presence of an inert gas, and then the gas is heated to a reaction temperature,
In other words, it is characterized in that the reaction is carried out by switching to synthesis gas, the temperature is raised by the heat of reaction, and the reaction is carried out at a predetermined reaction temperature under pressure. It has been found that this method can maintain and improve catalyst activity and achieve high selectivity.

, and to improve selectivity.

Another object of the present invention is to provide a method that can rationally initiate the above reaction in an extremely short period of time without reducing catalytic activity.

Another object of the present invention is to use Rh from 0.01 to
It contains 15.0% by weight, preferably 0.1-10.0% by weight, and Rh can be used in metallic form or as a rhodium salt or complex with a valence of 3 or less.

As co-catalysts, Mn, Mg+ Sc, Ir, Z
r, or.

No, W, U, Th, etc., and alkali metals or alkaline earth metals such as Na, K, Lf, Cs, R
h, Ca, SL, Ha, etc., but Mn is particularly preferred, and any element of the lanthanide or actinide series can be used as the rare earth element as a cocatalyst.

Compounds used as promoters include inorganic acid salts such as halide-sulfate-81 acid salts and carbonate salts, and organic acid salts such as oxides, hydroxides, acetate salts, formic acid salts, and oxalate salts. Any acid salt can be used. However, compounds soluble in water or other suitable catalysts are preferably used to facilitate the loading of these catalyst components onto the carrier.

As the carrier, silica gel, activated carbon, activated alumina, titanium oxide, thorium oxide, zeolite, etc. are used, and silica gel is particularly preferred.The carrier may be in any known form such as powder or pellet. However, those having a specific surface area of 1 to 1000 rn'/g are preferred.

Reduction of the Rh catalyst is generally carried out using hydrogen at a temperature of 300°C to 800°C, but in the present invention, the reaction conditions include a CD:H ratio of 30:1 to 1:5, preferably using a ratio of 20:1 to 1:3, 150 to 450°C,
Pressure 1-300 atm, preferably 200-350°C, 2
At 0-200% pressure, space velocity 10-10/h,
Preferably, the reaction is carried out at a temperature of 10 to 10 hours.6 The reaction temperature is most preferably around 250°C.
However, it is common practice to gradually increase the reaction temperature in response to a decrease in catalyst activity that occurs over time.

Therefore, in the present invention, when starting the reaction, the temperature is raised while flowing an inert gas such as nitrogen gas under pressure into the reaction system until the reaction is heated to around 200°C or near the optimum temperature. The method is characterized in that the inert gas is switched to synthesis gas at a certain temperature, the temperature is rapidly raised to the desired reaction temperature by the generation of reaction heat, and the reaction is carried out under pressure.

As a result, catalyst activity and selectivity are significantly improved, and an increase in space-time yield is achieved.

In the present invention, the temperature at which the inert gas is switched to the synthesis gas is 0 to 100°C lower than the reaction temperature.1 Usually 20 to
It is carried out at a temperature of 50°C.

To date, the reaction system has been heated by increasing the pressure while flowing the raw material gas, ie, synthesis gas, at room temperature, and then raising the temperature in the presence of the raw material gas. This method may cause oxidation, and a decrease in catalytic activity is observed.

According to the present invention, the reaction is carried out by raising the temperature under an inert gas and then flowing the reaction gas to reach a predetermined reaction temperature due to heat generation in the reaction system, or by diluting the reaction gas with an inert gas. By starting the reaction, the reaction can be carried out safely and rationally with a high space-time yield, and there is no decrease in catalyst activity.Furthermore, according to the present invention, the reaction is heated in the presence of an inert gas, and then It is characterized in that the catalyst activity does not decrease even if the temperature of the reaction system is lowered to room temperature and the pressure is returned to normal pressure, and then the pressure and temperature of the reaction system is increased in the presence of synthesis gas.

That is, the reason for the low yield that occurs when the temperature is raised in the presence of synthesis gas from the beginning may be due to a decrease in the activity of the catalyst due to impurities or carbonyl gas in the synthesis gas at low temperatures, but the reason is not clear.

An outstanding effect is obtained by increasing the temperature of the rhodium catalyst in the presence of an inert gas according to the invention.

The reaction is usually carried out using a fixed bed reactor, but moving bed or fluidized bed reactors may also be used. There is no problem even if the components are mixed, N,
Inert gases such as He and Ar can also be used to dilute the raw material gas.

The present invention will be explained below with reference to Examples.

Examples 1 to 3 Bulk density 0.4 kg/! L, surface area 300m''/g (
By N adsorption B, E, T method. ) with silica gel 2
0g was used as a carrier. The impregnating solution contains 2.55 g of RhCl-
3IO.

0.047 g of HnCl.OHO, 0.427 g of IrCJl@HO.

Dissolve 0.028g of LiCJl in pure water, 22.5
A layered solution was obtained. A carrier is impregnated with this solution, and 80
After drying at 100 DEG C. for 20 hours, hydrogen was introduced at 201/hour at 100 DEG C. and normal pressure for 2 to 10 hours to reduce the mixture. Reduction time 2,
Three types of catalysts were obtained at 5° and 10 hours, and each was designated as catalyst A.

They are called catalyst B and catalyst C.

Synthesis experiments were conducted using catalysts A, B, and C.

The above catalyst was packed into a 10 mJl reactor, replaced with N gas, and heated from room temperature to 250°C in about 1 hour.
Table 1 shows the results of gas chromatography analysis of the liquid product and reaction gas collected after being held at ℃ for 10 minutes and replaced with GO/H gas.

Selectivity (00 mol%) - [(Number of moles of CO converted to each product) ÷ (Number of moles of CO consumed) ] X
10G Acetic acid activity (g/Imperial period) = [Amount of acetic acid produced (g)] ÷ [Amount of catalyst (see) x unit time (hours)] As a comparative example, the same catalyst as in Examples 1 to 3 was used from the beginning The temperature was raised from room temperature to the reaction temperature (300° C.) under CO/H gas at the same temperature increase rate as in the same example, and the reaction was carried out under the same reaction conditions as in the same example. The results obtained are shown in Table 1.

Examples 4 to 7 Examples 1 to 3 above except that the heat treatment temperature of the catalyst is different.
A C compound synthesis experiment was conducted under the same conditions as described above. The results are shown in Table 2. The reduction time of the catalyst was 2 hours, and the same catalyst as Catalyst A used in Examples 1 to 3 was used as the catalyst.

Claims (4)

[Claims] (1) In a method for producing acetic acid, acetaldehyde, and ethanol from synthesis gas containing carbon monoxide and hydrogen as main components under pressure and elevated temperature in the presence of a rhodium-based catalyst, heating the reaction system under pressure as the case may be. A method characterized by raising the temperature to near a predetermined reaction temperature in the presence of an inert gas, then switching the inert gas to raw material synthesis gas and carrying out the reaction under pressure. (2) Desired reaction temperature is 150 to 450°C, preferably 2
2. A method according to claim 1, wherein the temperature is 00-350<0>C, most preferably 250-300<0>C. (3) The method according to claim 2, wherein the temperature at the time of switching to the raw material gas is 0 to 100°C lower than the desired reaction temperature. (4) Reaction pressure is 1 to 300 atm, preferably 20 to 2
2. The method according to claim 1, wherein the pressure is 0.00 atm.