WO2015089703A1

WO2015089703A1 - Method for use in production of methanol and coproduction of c2-c4 alcohols

Info

Publication number: WO2015089703A1
Application number: PCT/CN2013/089536
Authority: WO
Inventors: 刘勇; 朱文良; 刘红超; 倪友明; 刘中民; 孟霜鹤; 李利娜; 刘世平; 周慧
Original assignee: 中国科学院大连化学物理研究所
Priority date: 2013-12-16
Filing date: 2013-12-16
Publication date: 2015-06-25

Abstract

The present invention relates to a method for production of methanol and coproduction of C2-C4 alcohols with a low-carbon ester and a synthesized gas cofeed as raw materials. A raw material gas containing a low-carbon ester and a synthesized gas is passed through a reactor fitted with a catalyst, and, multiple classes of alcohols are produced under the conditions of a reaction temperature of 150-350 °C, a reaction pressure of 0.1-20.0 MPa, a reaction volume space velocity of 100-40000 mlg^-1h^-1, and a low-carbon mass space velocity of 0.01-3.0h^-1, where the active components of the catalyst are copper and optionally zinc and/or aluminum. The method of the present invention synthesizes methanol on a catalyst of one reactor and, at the same time, coproduces a certain volume of C2-C4 alcohols under the condition of using the low-carbon ester and the synthesized gas cofeed, where the ratio between product alcohols is adjustable.

Description

Method for producing methanol in parallel to produce C2-C4 alcohol

Technical field

The present invention is in the field of catalytic chemistry and relates to a process for producing methanol in parallel to produce lower alcohols. Background technique

Methanol is an important chemical raw material and clean liquid fuel, mainly used as a solvent and raw materials for the preparation of formaldehyde, acetic acid, dimethyl ether, and MTG, MTO and other processes. In recent years, the production capacity of methanol at home and abroad has grown rapidly. From 2000 to 2008, the world's methanol production capacity increased by about 10% annually. Among them, China's methanol production capacity grew at an average annual rate of 23.5%. In 2011, China's methanol production reached 20.35 million tons. With the promotion of MTO and other technologies, it is expected that methanol production will increase in the future. With the development of emerging technologies such as biodiesel and fuel cells, especially with the change in energy structure, methanol has developed into one of the important alternative energy sources for petroleum. China issued national standards for fuel methanol and M85 methanol gasoline in 2009. Therefore, in the near future, the demand for methanol in the world will increase.

Industrial methanol synthesis process is divided into high pressure method and medium and low pressure method [Lee S Methanol synthesis technology. Boca Raton, Florida, USA: CRC Press, Inc., 1990; Ertl G. etc Handbook of Heterogeneous Catalysis. Maiden, MA, USA : John Wiley & Sons, Inc., 2008: 2920-2949]. The high pressure method was industrialized by BASF in Germany in 1923. The method uses zinc chromium oxide as a catalyst to synthesize methanol by reacting carbon monoxide and hydrogen at 30-35 MPa and 300-400 °C. With the development of raw material gas purification technology, especially the desulfurization technology, the medium and low pressure methanol synthesis process has been developed successively by the companies represented by British ICI Company and German Lurgi Company. The medium and low pressure method can achieve high activity and high selectivity synthesis of methanol at a lower temperature (200-290 ° C) and a lower pressure (5 MPa). The catalyst used is a copper catalyst (CuO/ZnO/Al _{2 ).} 0 ₃ , CuO/ZnO/Cr ₂ 0 ₃ , CuO/ZnO/MnO). Since the mid-1970s, almost all new and expanded methanol synthesis plants in the world have adopted medium and low pressure synthesis processes.

China's methanol industry began in the 1950s and began to use high-pressure technology Into the methanol, the independent development of medium and low pressure methanol catalysts began in the late 1960s, and the C207 catalyst was first developed for the hydration process. The C301 and C302 catalysts developed in the 1980s are widely used in domestic methanol synthesis units.

Low-carbon alcohol (also known as C ₂₊ OH), generally refers to a fatty alcohol with a carbon number of 2-6. In addition to being used as a liquid fuel, it can also be used as a gasoline additive to increase the bismuth value. It is also an important basic raw material in the chemical industry. One of them has a wide range of applications [Li Debao et al., Progress in Chemistry, 2004 (16) 584-592; Ge Qingjie et al., Chemical Progress, 2009 (28;) 917-921]. At present, relatively concentrated systems for the synthesis of low-carbon alcohol catalysts mainly include modified methanol synthesis catalysts, Cu-Co groups and MoS ₂ based catalysts [Forzatti P etc. Catal. Rev. 1991 (33) 109-168; Mahdavi V etc. Appl. Catal. A 2005 (281) 259-265].

Due to the overcapacity in the domestic methanol market, if a part of other low-carbon alcohols can be co-produced while synthesizing methanol, product diversity and economy can be improved, and the ratio of methanol and low-carbon alcohol can be adjusted according to market demand, and product flexibility and The maneuverability of the device has important practical significance for the development of the new coal chemical industry. There is a need in the art to develop a process for the simultaneous production of other lower alcohols by the synthesis of methanol under co-feed conditions of low carbon esters and syngas. Summary of the invention

SUMMARY OF THE INVENTION An object of the present invention is to provide a process for synthesizing methanol to produce other lower alcohols (C2-C4 alcohols) by using a mixture of a lower carbon ester and a synthesis gas as a reaction material.

To this end, the present invention provides a process for producing methanol in parallel to produce C2-C4 alcohol, characterized in that a feed gas containing a lower carbon ester and a synthesis gas is passed through a reactor equipped with a catalyst at a reaction temperature of 150. Producing a polyhydric alcohol at a temperature of from -350 ° C, a reaction pressure of 0.1 to 20.0 MPa, a reaction volume space velocity of from 100 to 40000 mlg - ¹ ^ ¹ , and a low carbon ester mass space velocity of from 0.01 to 3.0 h ^-1 ; The active component is copper and optionally zinc and/or aluminum.

In a preferred embodiment, the lower alcohol ester is one or more of an aliphatic ester having a total carbon number of not more than 8 (ie, a carbon number of 8 or less); the polyhydric alcohol is ethanol, propanol, and butyl. One or more of the alcohols and methanol.

In a preferred embodiment, in the catalyst, the active component copper is 50.0-100.0% by weight of the total weight of the catalyst in terms of CuO; zinc is 0-35.0% by weight of the total weight of the catalyst in terms of ZnO; Aluminum accounts for 0-10.0% by weight of the total weight of the catalyst in terms of A1 ₂ 0 ₃ . In a preferred embodiment, the catalyst further contains one or more of manganese, molybdenum, zirconium, chromium, iron, cerium, magnesium, nickel, calcium as an auxiliary. More preferably, the auxiliaries are manganese, chromium, iron, magnesium, nickel, most preferably manganese, iron, chromium. Preferably, the adjuvant is from 0 to 5.0% by weight based on the total weight of the catalyst, based on its metal oxide.

In a preferred embodiment, the catalyst is reduced with H ₂ and / or synthesis gas prior to use.

In a preferred embodiment, the synthesis gas/low carbon ester molar ratio is 9 to: 1000/1 in the raw material gas, and the hydrogen/carbon monoxide molar ratio in the synthesis gas is 0.06 to 300/1. Preferably, the synthesis gas / lower carbon ester molar ratio is 40 to 560/1, and the hydrogen/carbon monoxide molar ratio of the synthesis gas is 0.3 to 丽1.

In a preferred embodiment, the syngas also contains carbon dioxide, nitrogen and formamidine, and carbon dioxide, nitrogen and formamidine comprise from 3 to 13% by mole of the synthesis gas.

In a preferred embodiment, the reaction temperature is 180 to 300 ° C, the reaction pressure is 1.0 to 10.0 MPa, the reaction volume space velocity is 400-30000 mlg - ¹ , and the lower ester Mass airspeed is 0.1~1.0h—

Advantageous effects of the present invention include, but are not limited to: providing a new reaction process for synthesizing methanol in parallel with a catalyst of a low-carbon ester and syngas to produce ethanol, propanol, The addition of butanol, a lower ester promotes catalytic activity and does not affect catalyst life. The ratio of each lower alcohol can be adjusted by changing the reaction conditions, which greatly improves product flexibility and market adaptability. detailed description

The method of the invention utilizes a co-feed of a low-carbon ester and a syngas as a reaction raw material to synthesize methanol to produce another low-carbon alcohol in parallel, wherein a raw material gas containing a lower-carbon ester and a synthesis gas is passed through a reactor equipped with a catalyst in the reaction. Producing a polyhydric alcohol at a temperature of 150 to 350 ° C, a reaction pressure of 0.1 to 20.0 MPa, a reaction volume space velocity of 100 to 40000 mlg ¹ ^ ¹ , and a low carbon ester mass space velocity of 0.01 to 3.0 h ^-1 ; The active component in the catalyst is copper, and may also contain zinc and/or aluminum.

The lower carbon ester is one or a mixture of any of several aliphatic esters having a total carbon number of not more than 8. For example, the lower carbon ester is ethyl formate, propyl formate, butyl formate, methyl acetate, ethyl acetate, propyl acetate, butyl acetate, methyl propionate, ethyl propionate, propyl propionate. Butyl propionate a mixture of ester, methyl butyrate, ethyl butyrate, propyl butyrate, butyl butyrate or a mixture of any of the following; the lower alcohol is one of methanol, ethanol, propanol, butanol or A variety.

In the catalyst, preferably, the active component copper is 50.0-100.0% by weight based on the total weight of the catalyst, and the promoter zinc is 0-35.0% by weight based on the total weight of the catalyst; The aluminum agent is 0-10.0% by weight based on the total weight of the catalyst, based on the metal oxide.

The catalyst may further contain a composition of one or any of manganese, molybdenum, zirconium, chromium, iron, cerium, magnesium, nickel, calcium, and more preferably, the auxiliary agent is manganese. Chromium, iron, magnesium, and nickel are most preferably manganese, iron, and chromium. It is 0-5.0 wt% based on the total weight of the catalyst, based on the metal oxide (e.g., MnO, Cr ₂ O ₃ , Fe ₂ O ₃ , MgO, NiO, etc.).

The catalyst may be first reduced with H ₂ and/or syngas prior to the reaction. It is subjected to reduction treatment for 1 to 100% of H ₂ or synthesis gas (H _{2 /} CO = 0.5 to 50) at a temperature of 180 to 350 ° C and a pressure of 0.1 to 5.0 MPa for 5 to 60 hours.

In the raw material gas, the synthesis gas/low carbon ester molar ratio is 9 to 1000/1, and the hydrogen/carbon monoxide molar ratio in the synthesis gas is 0.06 to 300/1.

The syngas may also contain carbon dioxide, nitrogen and formamidine, which may comprise from 3 to 13% by mole of the synthesis gas.

In the raw material gas, the synthesis gas/low carbon ester molar ratio is 40 to 560/1, and the hydrogen/carbon monoxide molar ratio in the synthesis gas is 0.3 to: 100/1.

Preferably, the reaction conditions are: a reaction temperature of 180 to 300 ° C, a reaction pressure of 1.0 to 10.0 MPa, a reaction volume space velocity of 400 to 30 000 mlg ¹ ^ ¹ , and a low carbon ester mass space velocity of 0.1 to: 1.Oh-

The catalyst of the present invention (also referred to as a copper-based catalyst) is preferably prepared by a coprecipitation method, and includes the following steps:

a) adding a solution containing Cu ²⁺ and optionally Zn ²⁺ and/or Al ³⁺ ions to a precipitant solution at 25-60 ° C, stirring the resulting precipitate to homogeneity, and obtaining a precipitate having a pH of 7.0- 1); b) the precipitate obtained in step a) is aged for 5 to 60 hours, dried at 80-160 ° C and calcined at 240-500 ° C to obtain a calcined sample;

c) optionally, the calcined sample obtained in step b) is placed in a salt solution containing one or more of the components manganese, molybdenum, zirconium, chromium, iron, strontium, magnesium, nickel, calcium The catalyst is obtained by dipping one or more times, drying after drying at 80-160 ° C, and calcination at 240-500 ° C.

The main advantages of the present invention are mainly: under the condition of co-feeding of low-carbon ester and syngas, in one One reactor synthesizes methanol to produce low-carbon alcohol in parallel (the ratio of methanol and low-carbon alcohol is adjustable), the addition of low-carbon ester promotes catalytic activity and does not affect the life of the catalyst, greatly improving product flexibility and Market adaptability. The invention is described in detail below by way of examples, but the invention is not limited to the examples.

Example 1: Catalyst preparation

1) Preparation of 100% CuO catalyst

121 g of Cu(N0 ₃ ) ₂ -3H ₂ 0 was dissolved in 2000 ml of deionized water, and 68.0 g of concentrated aqueous ammonia (25-28%) was diluted with 1500 ml of deionized water. The aqueous ammonia solution was vigorously stirred at room temperature, and then the metal nitrate aqueous solution was slowly added to the aqueous ammonia solution for about 60 minutes. The pH of the precipitate was adjusted to 10.0 with an aqueous ammonia solution, and after stirring for 200 mm, it was aged for 36 hours. The precipitate was washed with deionized water to neutrality and centrifuged. The obtained precipitate was dried in an oven at 120 ° C for 24 hours. After drying, the sample was placed in a muffle furnace, heated to 400 ° C at a heating rate of rC / mm, and calcined for 5 hours to obtain a calcined sample. This catalyst is referred to as CAT1.

2) Preparation of 85% CuO/10% ZnO/5% Al ₂ O ₃ catalyst

Dissolve 102.85g Cu(N0 ₃ ) ₂ -3H ₂ 0 , 12.00g Ζη(Ν0 ₃ ) ₂ ·6Η ₂ 0 , 14.71g Α1(Ν0 ₃ ) ₃ ·9Η ₂ 0 in 2000ml deionized water, deionized with 1500ml The water was diluted with 72.52 g of concentrated ammonia (25-28%). The aqueous ammonia solution was vigorously stirred at room temperature, and then the mixed metal nitrate aqueous solution was slowly added to the aqueous ammonia solution for about 60 minutes. The pH of the precipitate was adjusted to 10.0 with an aqueous ammonia solution, and after stirring for 200 mm, it was aged for 36 hours. The precipitate was washed with deionized water to neutrality and centrifuged. The obtained precipitate was dried in an oven at 120 ° C for 24 hours. After drying, the sample was placed in a muffle furnace, heated to 400 ° C at a heating rate of rC / mm, and calcined for 5 hours to obtain a calcined sample. This catalyst is referred to as CAT3.

3) Preparation of 75% CuO/13% ZnO/5% Al ₂ O ₃ /l% MnO/l% NiO catalyst 96.80g Cu(N0 ₃ ) ₂ -3H ₂ 0 , 15.60g Ζη(Ν0 ₃ ) ₂ · 6Η20 , 14.71g Α1(Ν0 ₃ ) ₃ ·9Η20 is dissolved in 2000ml of deionized water, and 72.62g of concentrated ammonia water (25-28%) is diluted with 1500ml of deionized water. The aqueous ammonia solution was vigorously stirred at room temperature, and then the mixed metal nitrate aqueous solution was slowly added to the aqueous ammonia solution for about 60 minutes. Adjusting the precipitation with aqueous ammonia solution The pH was adjusted to 10.0, and after stirring for 200 mm, it was aged for 36 hours. The precipitate was washed with deionized water to neutrality and centrifuged. The obtained precipitate was dried in an oven at 120 ° C for 24 hours. After drying, the sample was placed in a muffle furnace, heated to 400 ° C at a heating rate of rC / mm, and calcined for 5 hours to obtain a calcined sample. Further, 1.41 g of Mn(N0 ₃ ) ₂ '4H20, 1.36 g of Ni(N0 ₃ ) ₂ -4H ₂ 0 was dissolved in 50 ml of deionized water, and a manganese and nickel aqueous solution was carried by dipping to the calcined sample, 80 The excess solvent is evaporated off at °C. The sample was dried in a 120 ° C oven for 24 hours. After drying, the sample was placed in a muffle furnace, heated to 400 ° C at a heating rate of rC / mm, and calcined for 3 hours to obtain a catalyst sample. The catalyst was recorded as CAT4. The rest of the catalysts CAT2 and CAT5~10 were prepared similarly to CAT3 and CAT4. The relationship between the specific preparation conditions of the catalyst and the numbering is shown in Table 1. The catalyst composition determined by XR (X-ray fluorescence spectroscopy, PANalytical, The Netherlands) is shown in Table 2.

Table 1: Catalyst preparation

Table 2: Catalyst composition determined by XRF

Example 2: Catalyst evaluation

The reaction volume space velocity in the present invention is defined as the volumetric flow rate of the reaction feedstock (in standard conditions) entering the reaction system per hour divided by the mass of the catalyst. Expressed in GHSV, the unit is mlg - 10 g of 20-40 mesh of the above catalyst is charged into the fixed bed reactor thermostat. Before the reaction, the catalyst was subjected to on-line reduction, the reduction temperature was 260 ° C, the pressure was 0.1 MPa, the reducing gas was 5% H ₂ + 95% N ₂ , and the reduction time was 24 h.

After the end of the reduction, purge the pipeline and the residual H _{2 in the} reactor with N ₂ , then switch the gas to a certain composition of syngas and pressurize, adjust the mass flow meter to the specified flow rate (standard condition), set the low carbon ester The high pressure feed pump is pumped to the specified flow rate and begins to react when the temperature and pressure are stabilized. The product was analyzed online and sampled once every hour. From the outlet of the reactor to the inlet of the gas chromatographic ten-way valve, all lines and back pressure valves are heated and insulated. Product analysis method

Chromatography: Agilent 7890A

FID column: HP-PLOT-Q 19091P-Q04, 30m x 0.32mm (inside diameter), 20μπι film thickness

Carrier gas: helium, 2 ml/min

Oven temperature: 50°C-240°C, 10°C/min

Hold at 240 ° C for 15 min

Inlet: Split (50:1); Temperature: 250°C Detector: FID; Temperature: 300 °C

TCD column: carbon molecular sieve column, TDX-01 2m X 2mm (inside diameter)

Carrier gas: helium, 35ml/min

Oven temperature: 50°C-240°C, 10°C/min

Hold at 240 ° C for 15 min

Inlet: septum purge inlet; temperature: 250°C

Detector: TCD; Temperature: 300 ° C

1) On the above catalysts of different compositions, ethyl propionate (C ₅ H _1Q 0 ₂ ) and synthesis gas (volume composition 70.59% 3⁄4/23.53% CO/3.52% CO ₂ + N ₂ /2.36% C ₅ H _1Q O ₂ ) The reaction performance of co-feeding methanol to produce C2 C4 lower alcohol in parallel is shown in Table 3.

Reaction conditions: reaction temperature 230 ° C, reaction pressure 4.0 MPa, feed gas composition molar ratio H ₂ /CO/CO ₂ +N ₂ /C ₅ H ₁₀ O ₂ =30/10/1.5/l (70.59% 3⁄4/23.53 %CO/3.52%CO ₂ +N ₂ /2. 36%C ₅ H ₁₀ O ₂ ), total volume space velocity GHSV=2792mlg— ― Low carbon ester mass space velocity WHSV _m acid B = 0.3h ¹ Table 3: Reaction performance of co-feeding of ethyl propionate and syngas on different catalysts to produce methanol and parallel production of C2~C4 lower alcohol

2) Catalyst CAT4 is co-fed with butyl acetate (C ₆ H ₁₂ 0 ₂ ) and syngas (volume composition 87.72% 3⁄4/11.70% CO/0.58% C ₆ H ₁₂ O ₂ ) at different temperatures. The reaction performance of C2~C4 lower alcohols produced in parallel is shown in Table 4. Reaction conditions: 6.5 MPa, H ₂ /CO/C ₆ H ₁₂ 0 ₂ =l 50/20/1 (87.72% H ₂ /11.70% CO /0.58% C ₆ H ₁₂ O ₂ ), GHSV=26635mlg" ¹ h " ¹ , WHSV acetic acid Dingku = 0.0111 Table 4: Effect of reaction temperature on the reaction performance of CAT4 catalyst in the co-feed of methanol to produce C2 C4 lower alcohol

3) Catalyst CAT7 was prepared by co-feeding propyl butyrate (C ₇ H ₁₄ 0 ₂ ) gas (volume composition 86.20% CO/12.93% CO/0.87% C ₇ H ₁₄ O ₂ ) under different pressures. The reaction performance of the parallel production of lower alcohols is shown in Table 5.

Reaction conditions: 250 ° C, H ₂ /CO/C ₇ H ₁₄ O ₂ =100/15/l (86.20% CO/12.93% CO/0.87% C ₇ H ₁₄ O ₂ ), GHSV=9903 mlg" ^ ^-1 , WHSV Butyric acid C Cool = 0.5 ^ι

Table 5: Effect of Reaction Pressure on Catalytic Performance of Catalyst in the Production of C2 C4 Lower Alcohol in Parallel Production of CAT7 Butyl Acetate with Syngas

4) The reaction performance of methanol and parallel production of C2 C4 lower alcohol by co-feeding of low-carbon ester and syngas under different catalysts and different reaction conditions is shown in Table 6. Table 6: Reaction performance of methanol produced by co-feed of low-carbon ester and syngas under different catalysts and reaction conditions for parallel production of lower alcohol

According to the above embodiment and data, the following conclusions can be drawn:

On a specific catalyst, in a reactor, under a suitable reaction condition, a certain amount of low-carbon ester (low-carbon ester mass space velocity of 0.01 to 3.0 h - preferably O.ll. Oh- ¹ ) and syngas ( Co-feeding of hydrogen and carbon oxides will effectively produce polyhydric alcohols including methanol and C2-C4 lower alcohols. By adjusting the ratio of syngas/lower ester, it is convenient to regulate the ratio between the products C1-C4 lower alcohols without affecting the catalytic efficiency of the process, and then adjust the product output according to market changes, improve the ability of enterprises to cope with market risks and industry. The operational flexibility of the device.

The invention has the advantages that, by using the copper-based catalyst of the invention, the synthesis of methanol and the co-production of C2-C4 lower alcohol are achieved by adding a small amount of a lower ester (the total carbon number of the lower carbon ester is not higher than 8) in the synthesis gas, and The addition of the lower carbon ester promotes the catalytic activity (increased single pass conversion of carbon monoxide) without affecting the catalyst life (the catalyst life is similar to that of the single synthesis gas hydrogenation to methanol). The product composition can be easily regulated by changing the syngas/lower ester feed ratio for flexible operation and greater economics.

It should be noted that various modifications to these embodiments can be implemented by those skilled in the art without departing from the principles of the present invention, and such modifications are also considered to be within the scope of the present invention. .

Claims

Rights request

A method for producing a methanol-parallel C2-C4 alcohol, characterized in that a raw material gas containing a lower carbon ester and a synthesis gas is passed through a reactor equipped with a catalyst at a reaction temperature of 150 to 350 ° C , the reaction pressure is 0.1 to 20.0 MPa, the reaction volume space velocity is 100 to 40000 mlg" ¹ ^ ¹ , and the low-carbon ester mass space velocity is 0.01 to 3.0 h ^-1 to produce methanol in parallel to produce C2-C4 alcohol; The active component of the catalyst is copper and optionally zinc and/or aluminum.

2. The method according to claim 1, wherein the lower carbon ester is one or more of aliphatic esters having a total carbon number of not higher than 8.

3. The method according to claim 1, wherein in the catalyst, the active component copper accounts for 50.0-100.0% by weight of the total weight of the catalyst in terms of CuO; zinc accounts for the total catalyst in terms of ZnO. 0-35.0% by weight of aluminum; aluminum is 0-10.0% by weight based on the total weight of the catalyst in terms of A1 ₂ 0 ₃ .

4. The method according to claim 1, wherein the catalyst further contains one or more of manganese, molybdenum, zirconium, chromium, iron, cerium, magnesium, nickel, and calcium as an auxiliary.

5. The method according to claim 4, wherein the catalyst auxiliary agent is one or more of manganese, chromium, iron, magnesium, and nickel.

6. Process according to claim 5, characterized in that the auxiliaries comprise from 0 to 5.0% by weight of the total weight of the catalyst, based on its metal oxide.

7. The method according to claim 1, wherein the catalyst is subjected to a reduction treatment with H ₂ and/or synthesis gas before use.

8. The method according to claim 1, wherein a synthesis gas/low carbon ester molar ratio of 9 to 1000/1 in the raw material gas, and a hydrogen/carbon monoxide molar ratio of 0.06 in the synthesis gas. ~300/1.

9. The method according to claim 8, wherein the synthesis gas/low carbon ester molar ratio is 40 to 560/1 in the raw material gas, and the hydrogen/carbon monoxide molar ratio in the synthesis gas is 0.3 to 9. Li.

10. The method according to claim 1, wherein the synthesis gas contains carbon dioxide, nitrogen, and formazan, and the carbon dioxide, nitrogen, and formazan account for 3% of the synthesis gas. 13%.

The method according to claim 1, wherein the reaction temperature is 180 to 300 ° C, the reaction pressure is 1.0 to 10.0 MPa, and the reaction volume space velocity is 400 to 30 000 mlg - ¹ ^ ¹ , and the low carbon ester mass space velocity is 0.1 to 1.0 h—