JPWO2006016583A1 - Method for producing liquefied petroleum gas - Google Patents

Abstract

A synthesis gas is produced from a raw material gas containing a carbon-containing raw material such as natural gas and a reaction product gas obtained by a dimethyl ether synthesis reaction and recycled, and dimethyl ether and carbon dioxide are produced from the resultant synthesis gas. A reaction product gas containing carbon is produced, a carbon dioxide-containing gas is separated from the reaction product gas to obtain a dimethyl ether-containing gas, and a liquefied petroleum gas is produced from the dimethyl ether-containing gas and hydrogen.

Description

  The present invention relates to a method for producing liquefied petroleum gas whose main component is propane or butane from a carbon-containing raw material such as natural gas via synthesis gas and dimethyl ether.

  The liquefied petroleum gas (LPG) is obtained by compressing a petroleum-based or natural gas-based hydrocarbon that is in a gaseous state at normal temperature and pressure, or by simultaneously cooling it into a liquid state, and its main component is propane or butane. LPG that can be stored and transported in a liquid state has excellent portability, and unlike natural gas that requires a pipeline for supply, it can be supplied to any place in a filled state in a cylinder. There is. For this reason, LPG mainly composed of propane, that is, propane gas, is widely used as a fuel for home use and business use. Currently, propane gas is supplied to approximately 25 million households (more than 50% of all households) in Japan. In addition to household and commercial fuels, LPG is also used as fuel for moving bodies (mainly butane gas) such as cassette stoves and disposable lighters, industrial fuel, and automobile fuel.

  Conventionally, LPG is obtained by 1) a method of recovering from wet natural gas, 2) a method of recovering from crude oil stabilization (vapor pressure adjustment), 3) a method of separating / extracting what is produced in an oil refining process, etc. Has been produced.

  Propane gas, which is used as a fuel for LPG, particularly for home and business use, is very useful if a new production method that can be industrially implemented can be established in the future.

As a method for producing LPG, Patent Document 1 discloses a methanol synthesis catalyst such as Cu—Zn, Cr—Zn, and Pd, specifically, a CuO—ZnO—Al ₂ O ₃ catalyst and a Pd / SiO ₂ catalyst. And a synthesis gas composed of hydrogen and carbon monoxide in the presence of a mixed catalyst obtained by physically mixing a zeolite having an average pore diameter of approximately 10 mm (1 nm) or more, specifically, a methanol conversion catalyst composed of Y-type zeolite. A method of reacting to produce liquefied petroleum gas or a hydrocarbon mixture having a composition close to this is disclosed.

As a method for producing LPG, Non-Patent Document 1 discloses that 4 wt% Pd / SiO ₂ , a Cu—Zn—Al mixed oxide [Cu: Zn: Al = 40: 23: 37 (atom), which is a catalyst for methanol synthesis. Ratio)] or a Cu-based catalyst for low-pressure methanol synthesis (trade name: BASF S3-85) and high-silica Y-type zeolite with SiO ₂ / Al ₂ O ₃ = 7.6 treated with steam at 450 ° C. for 1 hour. And a method for producing C2-C4 paraffins from synthesis gas via methanol and dimethyl ether with a selectivity of 69-85%.

On the other hand, Non-Patent Document 2 discloses a method for producing LPG using at least one of methanol and dimethyl ether as a raw material. Specifically, under slight pressure, at a reaction temperature of 603 K (330 ° C.), a raw material gas of methanol: H ₂ : N ₂ = 1: 1: 1 has a methanol-based LHSV of 20 h ⁻¹ , and the first stage is ZSM-5 And two catalyst layers (ZSM-5 / Pt-C Series) whose subsequent stage is Pt-C, or a mixed catalyst layer (ZSM-5 / Pt-C Pellet) composed of ZSM-5 and Pt-C. -Mixture) to carry out the LPG synthesis reaction.
Japanese Patent Laid-Open No. 61-23688 “Selective Synthesis of LPG from Synthesis Gas”, Kaoru Fujimoto et al. Bull. Chem. Soc. Jpn. 58, p. 3059-3060 (1985) “Methanol / Dimethyl Ether Conversion on Zeolites Catalysts for Indirect Synthesis of LPG from Natural Gas”, Yingjie Jin et al. , 92nd Catalyst Conference, Proceedings of Conference A, p. 322, September 18, 2003

  An object of the present invention is to economically produce a hydrocarbon whose main component is propane or butane, that is, liquefied petroleum gas (LPG), from a carbon-containing raw material such as natural gas, via synthesis gas and dimethyl ether. It is to provide a way that can be done.

According to the present invention,
(I) a synthesis gas production process for producing synthesis gas from a raw material gas containing a carbon-containing raw material and a carbon dioxide-containing gas recycled from the recycling process;
(Ii) Dimethyl ether for producing a dimethyl ether synthesis reaction product gas containing dimethyl ether and carbon dioxide from the synthesis gas obtained in the synthesis gas production process by reacting carbon monoxide with hydrogen in the presence of a catalyst for producing dimethyl ether. Manufacturing process,
(Iii) a separation step of separating a carbon dioxide-containing gas containing carbon dioxide and a dimethyl ether-containing gas containing dimethyl ether as a main component from the dimethyl ether synthesis reaction product gas obtained in the dimethyl ether production step;
(Iv) An olefin production process for producing an olefin-containing gas containing olefins whose main component is propylene or butene from the dimethyl ether-containing gas obtained in the separation process by reacting dimethyl ether in the presence of an olefin production catalyst. When,
(V) Liquefaction containing hydrocarbons whose main component is propane or butane from olefin-containing gas and hydrogen obtained in the olefin production process by reacting olefin and hydrogen in the presence of an olefin hydrogenation catalyst. An olefin hydrogenation process for producing petroleum gas;
(Vi) a method for producing a liquefied petroleum gas (1-1 LPG), comprising a recycling step of recycling a part or all of the carbon dioxide-containing gas separated in the separation step into a synthesis gas production step. Manufacturing method).

Moreover, according to the present invention,
(I) a synthesis gas production process for producing synthesis gas from a raw material gas containing a carbon-containing raw material and a carbon dioxide-containing gas recycled from the recycling process;
(Ii) Dimethyl ether for producing a dimethyl ether synthesis reaction product gas containing dimethyl ether and carbon dioxide from the synthesis gas obtained in the synthesis gas production process by reacting carbon monoxide with hydrogen in the presence of a catalyst for producing dimethyl ether. Manufacturing process,
(Iii) a separation step of separating a carbon dioxide-containing gas containing carbon dioxide and a dimethyl ether-containing gas containing dimethyl ether as a main component from the dimethyl ether synthesis reaction product gas obtained in the dimethyl ether production step;
(Iv) Olefin-containing gas containing hydrogen and olefins whose main components are propylene or butene from dimethyl ether-containing gas and hydrogen obtained in the separation step by reacting dimethyl ether in the presence of a catalyst for olefin production An olefin production process for producing
(V) A liquefied petroleum gas containing a hydrocarbon whose main component is propane or butane from the olefin-containing gas obtained in the olefin production process by reacting olefin and hydrogen in the presence of an olefin hydrogenation catalyst. An olefin hydrogenation process to be produced;
(Vi) A method for producing a liquefied petroleum gas (1-2 LPG), comprising a recycling step of recycling a part or all of the carbon dioxide-containing gas separated in the separation step to a synthesis gas production step. Manufacturing method).

Moreover, according to the present invention,
(I) a synthesis gas production process for producing synthesis gas from a raw material gas containing a carbon-containing raw material and a carbon dioxide-containing gas recycled from the recycling process;
(Ii) Dimethyl ether for producing a dimethyl ether synthesis reaction product gas containing dimethyl ether and carbon dioxide from the synthesis gas obtained in the synthesis gas production process by reacting carbon monoxide with hydrogen in the presence of a catalyst for producing dimethyl ether. Manufacturing process,
(Iii) a separation step of separating a carbon dioxide-containing gas containing carbon dioxide and a dimethyl ether-containing gas containing dimethyl ether as a main component from the dimethyl ether synthesis reaction product gas obtained in the dimethyl ether production step;
(Iv) Liquefaction containing hydrocarbons whose main component is propane or butane from dimethyl ether-containing gas and hydrogen obtained in the separation step by reacting dimethyl ether and hydrogen in the presence of a catalyst for liquefied petroleum gas production. A liquefied petroleum gas production process for producing petroleum gas;
(V) a method for producing a liquefied petroleum gas (second LPG production), comprising a recycling step of recycling a part or all of the carbon dioxide-containing gas separated in the separation step to a synthesis gas production step Method).

  Here, the synthesis gas refers to a mixed gas containing hydrogen and carbon monoxide, and is not limited to a mixed gas composed of hydrogen and carbon monoxide. The synthesis gas may be a mixed gas containing, for example, carbon dioxide, water, methane, ethane, ethylene, and the like. Syngas obtained by reforming natural gas usually contains carbon dioxide and water vapor in addition to hydrogen and carbon monoxide. The synthesis gas may be a coal gas obtained by coal gasification or a water gas produced from coal coke.

By synthesizing olefins whose main component is propylene or butene from dimethyl ether and then hydrogenating the resulting olefins or by reacting dimethyl ether with hydrogen, the main component is propane Alternatively, a hydrocarbon which is butane, that is, liquefied petroleum gas (LPG) can be produced. Dimethyl ether which is a reaction raw material can be produced from a synthesis gas which is a mixed gas containing hydrogen and carbon monoxide, and the synthesis gas includes a carbon-containing raw material such as natural gas, H ₂ O, O ₂ and It can be produced by reacting with at least one selected from the group consisting of CO ₂ .

  Therefore, LPG can be produced from carbon-containing raw materials such as natural gas via synthesis gas and dimethyl ether.

  According to the 1-1 LPG production method, 1-2 LPG production method, and second LPG production method of the present invention, LPG is produced more economically from carbon-containing raw materials such as natural gas. can do.

  When carbon monoxide and hydrogen are reacted to synthesize dimethyl ether, the reaction is represented by the following formula (1).

上記式（１）に示されるように、合成ガスからジメチルエーテルを合成する反応においては、二酸化炭素が副生する。

As shown in the above formula (1), carbon dioxide is by-produced in the reaction of synthesizing dimethyl ether from synthesis gas.

On the other hand, carbon dioxide can be returned to the synthesis gas by the CO ₂ reforming reaction shown in the following formula (2).

ジメチルエーテル合成反応により得られる、ジメチルエーテルと二酸化炭素とを含む反応生成ガス（ジメチルエーテル合成反応生成ガス）から二酸化炭素を分離し、これを合成ガス製造工程にリサイクルして、天然ガスなどの含炭素原料を改質するのに使用することにより、ＬＰＧをより経済的に製造することができる。

Carbon dioxide is separated from the reaction product gas (dimethyl ether synthesis reaction product gas) containing dimethyl ether and carbon dioxide obtained by the dimethyl ether synthesis reaction, and this is recycled to the synthesis gas production process to produce carbon-containing raw materials such as natural gas. By using it for modification, LPG can be produced more economically.

Furthermore, like the above formula (1), in terms of the stoichiometry for producing dimethyl ether, the composition of the synthesis gas is preferably H ₂ / CO (molar ratio) = 1. In the present invention, preferably, a synthesis gas containing carbon monoxide and hydrogen at CO: H ₂ = 1: 0.5 to 1: 1.5 (molar ratio) is used as a raw material for the dimethyl ether synthesis reaction. Thereby, dimethyl ether can be produced more efficiently and more economically, and as a result, LPG can be produced more economically.

However, carbon dioxide is recycled as described above, and a synthesis gas having a high carbon monoxide content, preferably carbon monoxide and hydrogen, is converted into CO: H ₂ = 1: 0.5 to 1: 1.5 ( It is not easy to produce synthesis gas containing in molar ratio). In a general synthesis gas production method and production conditions using a Ni-based catalyst or the like, carbonaceous (carbon) precipitation is likely to occur, and it is difficult to stably produce the synthesis gas over a long period of time.

In the present invention, carbon monoxide and hydrogen are preferably converted to CO: H ₂ = 1: 0. While carbon dioxide is recycled by producing synthesis gas by the method described in the later-described synthesis gas production step. This makes it possible to stably produce a synthesis gas containing 5 to 1: 1.5 (molar ratio) over a long period of time.

It is a process flow figure which shows the main structures about an example of the LPG manufacturing apparatus suitable for enforcing the manufacturing method of the 1-1st LPG of this invention. It is a process flowchart which shows the main structures about an example of the LPG manufacturing apparatus suitable for enforcing the 1-2 LPG manufacturing method of this invention. It is a process flow figure which shows the main structures about an example of the LPG manufacturing apparatus suitable for implementing the manufacturing method of the 2nd LPG of this invention.

Explanation of symbols

11 reformer 11a reforming catalyst (catalyst for synthesis gas production)
12 Reactor for dimethyl ether synthesis 12a Catalyst for dimethyl ether production 13 Separator 14 Reactor for olefin production 14a Catalyst for olefin production 15 Reactor for olefin hydrogenation 15a Catalyst for olefin hydrogenation 101, 102, 103, 104, 106, 107, 108, 109 Line 105 Recycle line 21 Reformer 21a Reforming catalyst (synthetic gas production catalyst)
22 Reactor for dimethyl ether synthesis 22a Catalyst for dimethyl ether production 23 Separator 24 Reactor for olefin production 24a Catalyst for olefin production 25 Reactor for olefin hydrogenation 25a Catalyst for olefin hydrogenation 201, 202, 203, 204, 206, 207, 208, 209 Line 205 Recycle line 31 Reformer 31a Reforming catalyst (catalyst for synthesis gas production)
32 Reactor for synthesis of dimethyl ether 32a Catalyst for production of dimethyl ether 33 Separator 34 Reactor for production of liquefied petroleum gas 34a Catalyst for production of liquefied petroleum gas 301, 302, 303, 304, 306, 307, 308 Line 305 Recycle line

  With reference to the drawings, an embodiment of an LPG production method (1-1 LPG production method, 1-2 LPG production method, and second LPG production method) of the present invention will be described.

  FIG. 1 shows an example of an LPG production apparatus suitable for carrying out the 1-1 LPG production method of the present invention.

  First, natural gas (methane) is supplied to the reformer 11 via lines 101 and 102 as a carbon-containing raw material. Although not shown, oxygen and / or water vapor is supplied to the line 102 as necessary. Further, the carbon dioxide-containing gas to be recycled is supplied from the separator 13 to the reformer 11 through the recycle line 105 and the line 102. In the reformer 11, a reforming catalyst (synthetic gas production catalyst) 11a is provided. The reformer 11 includes a heating unit (not shown) for supplying heat necessary for reforming. In the reformer 11, methane is reformed in the presence of the reforming catalyst, and a synthesis gas containing hydrogen and carbon monoxide is obtained.

  The synthesis gas thus obtained is supplied to the dimethyl ether synthesis reactor 12 via the line 103. In the reactor 12, a catalyst 12a for producing dimethyl ether is provided. In this reactor 12, a dimethyl ether synthesis reaction product gas containing dimethyl ether and carbon dioxide is produced from synthesis gas in the presence of a catalyst for producing dimethyl ether.

  The produced dimethyl ether synthesis reaction product gas is supplied to the separator 13 via the line 104 after moisture and the like are removed by gas-liquid separation or the like. In this separator 13, the dimethyl ether synthesis reaction product gas is separated into a dimethyl ether-containing gas containing dimethyl ether as a main component and a carbon dioxide-containing gas.

  The separated carbon dioxide-containing gas is recycled to the reformer 11 through the recycle line 105 and the line 102.

  On the other hand, the dimethyl ether-containing gas is supplied to the olefin production reactor 14 via the line 106. In the reactor 14, an olefin production catalyst 14a is provided. In this reactor 14, an olefin-containing gas containing olefins whose main components are propylene or butene is synthesized from a dimethyl ether-containing gas in the presence of a catalyst for olefin production.

  The synthesized olefin-containing gas is supplied to the olefin hydrogenation reactor 15 via the line 107. Further, hydrogen is supplied to the olefin hydrogenation reactor 15 via the line 108. In the reactor 15, an olefin hydrogenation catalyst 15a is provided. In this reactor 15, a hydrocarbon gas (lower paraffin-containing gas) whose main component is propane or butane is synthesized from an olefin-containing gas and hydrogen in the presence of an olefin hydrogenation catalyst.

  The synthesized hydrocarbon gas is subjected to pressure and cooling after removing moisture and the like as necessary, and LPG as a product is obtained from the line 109. LPG may remove hydrogen or the like by gas-liquid separation or the like.

  Although not shown, the LPG manufacturing apparatus is provided with a booster, a heat exchanger, a valve, an instrumentation control device, and the like as necessary.

  FIG. 2 shows an example of an LPG production apparatus suitable for carrying out the 1-2 LPG production method of the present invention. The 1-2 LPG production method is the same as the 1-1 LPG production method, except that hydrogen is supplied not to the olefin hydrogenation reactor but to the olefin production reactor. .

  First, natural gas (methane) is supplied to the reformer 21 via lines 201 and 202 as a carbon-containing raw material. Although not shown, oxygen and / or water vapor is supplied to the line 202 as necessary. Further, the carbon dioxide-containing gas to be recycled is supplied from the separator 23 to the reformer 21 via the recycle line 205 and the line 202. In the reformer 21, a reforming catalyst (synthetic gas production catalyst) 21a is provided. The reformer 21 includes heating means (not shown) for supplying heat necessary for reforming. In the reformer 21, methane is reformed in the presence of the reforming catalyst, and a synthesis gas containing hydrogen and carbon monoxide is obtained.

  The synthesis gas thus obtained is supplied to the dimethyl ether synthesis reactor 22 via the line 203. In the reactor 22, a catalyst 22a for dimethyl ether production is provided. In this reactor 22, a dimethyl ether synthesis reaction product gas containing dimethyl ether and carbon dioxide is produced from the synthesis gas in the presence of a catalyst for producing dimethyl ether.

  The produced dimethyl ether synthesis reaction product gas is supplied to the separator 23 via the line 204 after moisture and the like are removed by gas-liquid separation or the like. In this separator 23, the dimethyl ether synthesis reaction product gas is separated into a dimethyl ether-containing gas containing dimethyl ether as a main component and a carbon dioxide-containing gas.

  The separated carbon dioxide-containing gas is recycled to the reformer 21 through the recycle line 205 and the line 202.

  On the other hand, the dimethyl ether-containing gas is supplied to the olefin production reactor 24 via a line 206. Further, hydrogen is supplied to the olefin production reactor 24 via a line 207. In the reactor 24, an olefin production catalyst 24a is provided. In this reactor 24, an olefin-containing gas containing olefins whose main components are propylene or butene and hydrogen is synthesized from a dimethyl ether-containing gas in the presence of an olefin production catalyst.

  The synthesized olefin-containing gas is supplied to the olefin hydrogenation reactor 25 via a line 208. In the reactor 25, an olefin hydrogenation catalyst 25a is provided. In the reactor 25, a hydrocarbon gas (lower paraffin-containing gas) whose main component is propane or butane is synthesized from an olefin-containing gas containing hydrogen in the presence of an olefin hydrogenation catalyst.

  The synthesized hydrocarbon gas is subjected to pressure and cooling after removing moisture and the like as necessary, and LPG as a product is obtained from the line 209. LPG may remove hydrogen or the like by gas-liquid separation or the like.

  Although not shown, the LPG manufacturing apparatus is provided with a booster, a heat exchanger, a valve, an instrumentation control device, and the like as necessary.

  FIG. 3 shows an example of an LPG production apparatus suitable for carrying out the second LPG production method of the present invention. The second LPG production method is different from the 1-1 LPG production method and the 1-2 LPG production method in that LPG is synthesized from dimethyl ether in one step.

  First, natural gas (methane) is supplied to the reformer 31 via lines 301 and 302 as a carbon-containing raw material. Although not shown, oxygen and / or water vapor is supplied to the line 302 as necessary. Further, the carbon dioxide-containing gas to be recycled is supplied from the separator 33 to the reformer 31 via the recycle line 305 and the line 302. In the reformer 31, a reforming catalyst (synthetic gas production catalyst) 31a is provided. The reformer 31 includes a heating unit (not shown) for supplying heat necessary for reforming. In the reformer 31, methane is reformed in the presence of the reforming catalyst, and a synthesis gas containing hydrogen and carbon monoxide is obtained.

  The synthesis gas thus obtained is supplied to the dimethyl ether synthesis reactor 32 via a line 303. In the reactor 32, a catalyst 32a for producing dimethyl ether is provided. In this reactor 32, dimethyl ether synthesis reaction product gas containing dimethyl ether and carbon dioxide is produced from synthesis gas in the presence of a catalyst for producing dimethyl ether.

  The produced dimethyl ether synthesis reaction product gas is supplied to the separator 33 via a line 304 after moisture and the like are removed by gas-liquid separation or the like. In the separator 33, the dimethyl ether synthesis reaction product gas is separated into a dimethyl ether-containing gas containing dimethyl ether as a main component and a carbon dioxide-containing gas.

  The separated carbon dioxide-containing gas is recycled to the reformer 31 through a recycle line 305 and a line 302.

  On the other hand, the dimethyl ether-containing gas is supplied to the liquefied petroleum gas production reactor 34 via the line 306. Further, hydrogen is supplied to the liquefied petroleum gas production reactor 34 via the line 307. The reactor 34 is provided with a liquefied petroleum gas production catalyst 34a. In the reactor 34, hydrocarbon gas (lower paraffin-containing gas) whose main component is propane or butane is synthesized from the dimethyl ether-containing gas in the presence of the catalyst for producing the liquefied petroleum gas.

  The synthesized hydrocarbon gas is subjected to pressure and cooling after removing moisture and the like as necessary, and LPG as a product is obtained from the line 308. LPG may remove hydrogen or the like by gas-liquid separation or the like.

  Although not shown, the LPG manufacturing apparatus is provided with a booster, a heat exchanger, a valve, an instrumentation control device, and the like as necessary.

[Syngas production process]
In the synthesis gas production step, carbon monoxide and hydrogen are preferably converted into CO: H ₂ = 1: 0. 0 from the carbon-containing raw material and the carbon dioxide-containing gas separated from the dimethyl ether synthesis reaction product gas in the separation step described later. A synthesis gas containing 5 to 1: 1.5 (molar ratio) is produced. The carbon dioxide-containing gas may contain components other than carbon dioxide, for example, carbon monoxide and hydrogen which are unreacted raw materials in the dimethyl ether synthesis reaction, water, and the like. Furthermore, a raw material gas may be obtained by adding at least one selected from the group consisting of H ₂ O, O ₂ and CO ₂ to the carbon-containing raw material and the carbon dioxide-containing gas.

As the carbon-containing raw material, a substance containing carbon and capable of producing H ₂ and CO by reacting with CO ₂ can be used. As the carbon-containing raw material, those known as raw materials for synthesis gas can be used. For example, lower hydrocarbons such as methane and ethane, natural gas, naphtha, coal, and the like can be used.

  In the present invention, since a catalyst is usually used in a synthesis gas production process, a dimethyl ether production process, an olefin production process and an olefin hydrogenation process, or a liquefied petroleum gas production process, as a carbon-containing raw material (natural gas, naphtha, coal, etc.) Those having a low content of catalyst poisoning substances such as sulfur and sulfur compounds are preferable. Moreover, when a catalyst poisoning substance is contained in the carbon-containing raw material, a step of removing the catalyst poisoning substance such as desulfurization can be performed prior to the synthesis gas production process, if necessary.

The synthesis gas reacts the carbon-containing raw material as described above with at least one selected from the group consisting of CO ₂ , H ₂ O and O _{2 in} the presence of a synthesis gas production catalyst (reforming catalyst). It is manufactured by. In the present invention, carbon dioxide separated from the dimethyl ether synthesis reaction product gas in the separation step described later is used to reform the carbon-containing raw material from the viewpoint of economy and the like.

  The content of the carbon dioxide-containing gas in the raw material gas, that is, the content of the recycled raw material can be determined as appropriate.

  Further, the content of carbon dioxide in the carbon dioxide-containing gas to be recycled can be determined as appropriate, and need not be 100 mol%.

A synthesis gas containing carbon monoxide and hydrogen, which is a preferred composition in the present invention, at CO: H ₂ = 1: 0.5 to 1: 1.5 (molar ratio) is, for example, natural gas (methane) and carbon dioxide. Can be produced by a method (CO ₂ reforming) or the like. Among them, in the present invention, it is preferable to produce the synthesis gas by autothermal reforming.

In addition, for example, a shift reactor is provided downstream of a reformer that is a reactor for producing synthesis gas from the above raw materials, and the composition of the synthesis gas is adjusted by a shift reaction (CO + H ₂ O → CO ₂ + H ₂ ). You can also

In the present invention, the preferred composition of the synthesis gas produced from the synthesis gas production process is CO: H ₂ = 1: 0.5 to 1: 1.5 (molar ratio). The content ratio of hydrogen to carbon monoxide (H ₂ / CO; on a molar basis) in the produced synthesis gas is preferably 0.8 or more, and more preferably 0.9 or more. Further, the content ratio of hydrogen to carbon monoxide (H ₂ / CO; on a molar basis) in the produced synthesis gas is preferably 1.2 or less, and more preferably 1.1 or less.

  By setting the composition of the synthesis gas within the above range, dimethyl ether can be produced more efficiently and more economically in the next dimethyl ether production process, and as a result, LPG can be produced more economically. it can.

  In order to produce a synthesis gas having a composition within the above range, the type of synthesis gas production catalyst to be used, the composition of the raw material gas, the supply ratio of the carbon-containing raw material to the carbon dioxide-containing gas, and other reaction conditions are determined. What is necessary is just to select suitably.

A synthesis gas containing carbon monoxide and hydrogen at CO: H ₂ = 1: 0.5 to 1: 1.5 (molar ratio) can be produced, for example, by the following method.

In the presence of a reforming catalyst comprising a composite oxide having a composition represented by the following formula (A), a carbon-containing raw material, carbon dioxide, oxygen, and steam (steam) in the raw material gas introduced into the reactor ( Carbon dioxide + steam) / carbon ratio of 0.5 to 3, oxygen / carbon ratio of 0.2 to 1, temperature at the reactor outlet of 900 to 1100 ° C., pressure of 5 to 60 kg / cm ² By reacting, the synthesis gas used in the present invention can be produced.

_{M a · Co b · Ni c} · Mg d · Ca e · O f (A)
(Wherein M is selected from the group consisting of Group 6A elements, Group 7A elements, Group 8 transition elements excluding Co and Ni, Group 1B elements, Group 2B elements, Group 4B elements, and lanthanoid elements) Represents at least one element, a, b, c, d and e represent the atomic ratio of each element, and when a + b + c + d + e = 1, 0 ≦ a ≦ 0.1, 0.001 ≦ (b + c) ≦ 0. 3, 0 ≦ b ≦ 0.3, 0 ≦ c ≦ 0.3, 0.6 ≦ (d + e) ≦ 0.999, 0 <d ≦ 0.999, 0 ≦ e ≦ 0.999, and f is (Each element is necessary to maintain charge balance with oxygen.)
The (carbon dioxide + steam) / carbon ratio in the raw material gas introduced into the reactor is preferably about 0.5 to 2. The temperature at the outlet of the reactor is preferably 950 to 1050 ° C. The pressure at the outlet of the reactor is preferably 15 to 20 kg / cm ² .

The space velocity of the raw material gas is usually 500～200000Hr ^-1, preferably 1000~100000hr ^-1, 1000~70000hr ^-1 are more preferred.

  The composite oxide having the composition represented by the above formula (A) is a kind in which MgO and CaO have a rock salt type crystal structure, and a part of Mg or Ca atoms located in the lattice is substituted with Co, Ni or M It is a solid solution and forms a single phase.

  In the above formula (A), M is at least one element selected from the group consisting of manganese, molybdenum, rhodium, ruthenium, platinum, palladium, copper, silver, zinc, tin, lead, lanthanum and cerium. preferable.

  The M content (a) is 0 ≦ a ≦ 0.1, preferably 0 ≦ a ≦ 0.05, and more preferably 0 ≦ a ≦ 0.03. If the M content (a) exceeds 0.1, the activity of the reforming reaction decreases.

  The cobalt content (b) is 0 ≦ b ≦ 0.3, preferably 0 ≦ b ≦ 0.25, and more preferably 0 ≦ b ≦ 0.2. When the cobalt content (b) exceeds 0.3, it is difficult to sufficiently obtain the carbonaceous precipitation preventing effect.

  The nickel content (c) is 0 ≦ c ≦ 0.3, preferably 0 ≦ c ≦ 0.25, and more preferably 0 ≦ c ≦ 0.2. If the nickel content (c) exceeds 0.3, it is difficult to sufficiently obtain the carbonaceous precipitation preventing effect.

  The total amount (b + c) of the cobalt content (b) and the nickel content (c) is 0.001 ≦ (b + c) ≦ 0.3, and 0.001 ≦ (b + c) ≦ 0.25. It is preferable that 0.001 ≦ (b + c) ≦ 0.2. When the total content (b + c) exceeds 0.3, it becomes difficult to sufficiently obtain the carbonaceous precipitation preventing effect. On the other hand, when the total content (b + c) is less than 0.001, the reaction activity decreases.

  The total amount (d + e) of the magnesium content (d) and the calcium content (e) is 0.6 ≦ (d + e) ≦ 0.9998, and 0.7 ≦ (d + e) ≦ 0.9998. Preferably, 0.77 ≦ (d + e) ≦ 0.9998 is more preferable.

  Among these, the magnesium content (d) is 0 <d ≦ 0.999, preferably 0.2 ≦ d ≦ 0.9998, and more preferably 0.37 ≦ d ≦ 0.9998. . The calcium content (e) is 0 ≦ e <0.999, preferably 0 ≦ e ≦ 0.5, and more preferably 0 ≦ e ≦ 0.3. This catalyst may not contain calcium.

  The total amount (d + e) of the magnesium content (d) and the calcium content (e) is determined by the balance of the M content (a), the cobalt content (b), and the nickel content (c). (D + e) exhibits an excellent effect on the reforming reaction at any ratio within the above range. However, if the contents of calcium (e) and M (a) are large, the effect of suppressing carbonaceous precipitation is high. Although it exists, there exists a tendency for a catalyst activity to become low compared with the case where there is much magnesium (d). From the viewpoint of activity, it is preferable that the calcium content (e) is 0.5 or less and the M content (a) is 0.1 or less.

  The reforming catalyst to be used is preferably such that at least one of M, Co and Ni is highly dispersed in the composite oxide. Here, the dispersion is defined as the ratio of the number of atoms exposed on the catalyst surface to the total number of atoms of the supported metal. That is, if the number of atoms of a metal element of Co, Ni or M or a compound thereof is A and the number of atoms exposed on the particle surface among these atoms is B, B / A is the dispersity. By using a reforming catalyst in which at least one of M, Co, and Ni is highly dispersed in the composite oxide, the reaction becomes more active and the reaction proceeds stoichiometrically. Is more effectively prevented.

  Examples of a method for producing such a reforming catalyst include an impregnation support method, a coprecipitation method, a sol-gel method (hydrolysis method), and a uniform precipitation method.

  The above reforming catalyst is usually subjected to an activation treatment before being used for the production of synthesis gas. In the activation treatment, the catalyst is heated in the temperature range of 500 to 1000 ° C., preferably 600 to 1000 ° C., more preferably 650 to 1000 ° C. for about 0.5 to 30 hours in the presence of a reducing gas such as hydrogen gas. To do. The reducing gas may be diluted with an inert gas such as nitrogen gas. This activation treatment can also be performed in a reactor that performs the reforming reaction. By this activation treatment, catalytic activity is expressed.

As another method for producing the synthesis gas used in the present invention, the carbon-containing raw material is partially oxidized to produce a mixed gas having a temperature of at least 600 ° C. containing the unreacted carbon-containing raw material, and then this high temperature At least one selected from the group consisting of rhodium, ruthenium, iridium, palladium, and platinum as a carrier made of a metal oxide having an electronegativity of metal ions of 13 or less. Presence of a catalyst having a specific surface area of 25 m ² / g or less supported on a seed metal (catalyst metal) and a catalyst metal loading of 0.0005 to 0.1 mol% relative to the support metal oxide in terms of metal. Below, there is a method of producing a synthesis gas by reacting carbon dioxide (which may be carbon dioxide and steam) under pressurized conditions. Moreover, the electronegativity of metal ions is 13 or less using a mixed gas comprising a carbon-containing raw material, an oxygen-containing gas (air, oxygen, etc.), and carbon dioxide gas (may be carbon dioxide and steam). A support made of a metal oxide is loaded with at least one metal (catalyst metal) selected from the group consisting of rhodium, ruthenium, iridium, palladium and platinum, a specific surface area of 25 m ² / g or less, and a supported amount of the catalyst metal. In the presence of a catalyst in an amount of 0.0005 to 0.1 mol% with respect to the support metal oxide in a metal conversion amount, the carbon-containing raw material in the mixed gas is partially oxidized to include at least an unreacted carbon-containing raw material. A mixed gas having a temperature of 600 ° C. is generated, and this unreacted carbon-containing raw material is reacted with carbon dioxide gas (which may be carbon dioxide and steam) under pressure. And a method of manufacturing a gas.

  Here, the catalyst metal may be supported in a metal state, or may be supported in the state of a metal compound such as an oxide. Further, the metal oxide used as the carrier may be a single metal oxide or a composite metal oxide.

  The electronegativity of metal ions in the metal oxide for support is 13 or less, preferably 12 or less, and more preferably 10 or less. When the electronegativity of the metal ion in the metal oxide exceeds 13, carbon deposition becomes remarkable when the catalyst is used. Moreover, the lower limit of the electronegativity of metal ions in the metal oxide for support is usually about 4.

  In addition, the electronegativity of the metal ion in the metal oxide is defined by the following formula.

Xi = (1 + 2i) Xo
Xi: Electronegativity of metal ions,
Xo: metal electronegativity,
i: the number of valence electrons of the metal ion.

  When the metal oxide is a composite metal oxide, the average metal ion electronegativity is used, and the value is calculated based on the electronegativity of each metal ion contained in the composite metal oxide. The sum of the product multiplied by the mole fraction of the product.

  Pauling's electronegativity is used for the metal electronegativity (Xo). Pauling's electronegativity is described in Table 15.4 of “Ryoichi Fujishiro, Moore Physical Chemistry (4th edition), Tokyo Kagaku Dojin, p.707 (1974)”. The electronegativity (Xi) of metal ions in the metal oxide is described in detail, for example, in “Catalyst Society, Catalyst Course, Vol. 2, p. 145 (1985)”.

Examples of such metal oxides include metal oxides containing one or more metals such as Mg, Ca, Ba, Zn, Al, Zr, and La. Specific examples of such metal oxides include magnesia (MgO), calcium oxide (CaO), barium oxide (BaO), zinc oxide (ZnO), alumina (Al ₂ O ₃ ), zirconia (ZrO ₂ ), Single metal oxides such as lanthanum oxide (La ₂ O ₃ ), MgO / CaO, MgO / BaO, MgO / ZnO, MgO / Al ₂ O ₃ , MgO / ZrO ₂ , CaO / BaO, CaO / ZnO, CaO / Al ₂ O ₃ , CaO / ZrO ₂ , BaO / ZnO, BaO / Al ₂ O ₃ , BaO / ZrO ₂ , ZnO / Al ₂ O ₃ , ZnO / ZrO ₂ , Al ₂ O ₃ / ZrO ₂ , La ₂ O Examples thereof include composite metal oxides such as ₃ / MgO, La ₂ O ₃ / Al ₂ O ₃ , and La ₂ O ₃ / CaO.

Used specific surface area of the catalyst is not more than ^{25 m} 2 / g, preferably not more than ^{20 m} 2 / g, more preferably not more than ^{15m 2 / g, 10m 2 /} g or less is particularly preferred. Moreover, the lower limit of the specific surface area of the catalyst used is usually about 0.01 m ² / g. By setting the specific surface area of the catalyst within the above range, the carbon deposition activity of the catalyst can be more sufficiently suppressed.

In the catalyst used here, the specific surface area of the catalyst and the specific surface area of the metal oxide as a support are substantially the same. Therefore, the specific surface area of the metal oxide is a carrier is less ^{25 m} 2 / g, preferably not more than ^{20 m} 2 / g, more preferably not more than ^{15m 2 / g, 10m 2 /} g or less is particularly preferred. Moreover, the lower limit of the specific surface area of the metal oxide as a support is usually about 0.01 m ² / g.

  Here, the specific surface area of the metal oxide as a catalyst or a carrier is measured at a temperature of 15 ° C. by the BET method.

The catalyst having a specific surface area of 25 m ² / g or less is obtained by calcining a metal oxide as a support at 300 to 1300 ° C., preferably 650 to 1200 ° C. before supporting the catalyst metal, and after the catalyst metal is supported, It can be obtained by further firing the support at 600 to 1300 ° C, preferably 650 to 1200 ° C. Further, after the catalyst metal is supported on the metal oxide as the carrier, the obtained catalyst metal support can be obtained by firing at 600 to 1300 ° C, preferably 650 to 1200 ° C. By controlling the calcination temperature and the calcination time, the specific surface area of the metal oxide which is the catalyst or the support obtained can be controlled.

  The amount of the catalyst metal supported on the metal oxide as the support is 0.0005 to 0.1 mol% in terms of metal. The amount of the catalyst metal supported on the metal oxide as the carrier is preferably 0.001 mol% or more, and more preferably 0.002 mol% or more, in terms of metal. Further, the supported amount of the catalyst metal with respect to the metal oxide as the carrier is preferably 0.09 mol% or less in terms of metal.

  The catalyst as described above has a small specific surface area of the catalyst and a very small amount of the catalyst metal supported, so that it has a sufficient synthesis gasification activity for the carbon-containing raw material, and the carbon deposition activity is remarkably suppressed. It is a thing.

  Such a catalyst can be prepared according to a known method. As a method for producing a catalyst, for example, a metal oxide as a support is dispersed in water, a catalyst metal salt or an aqueous solution thereof is added and mixed, and then the metal oxide on which the catalyst metal is supported is separated from the aqueous solution. Drying and firing method (impregnation method) or exhausting the metal oxide as the carrier, adding a small amount of metal salt solution for the pore volume to make the surface of the carrier evenly wet, then drying and firing The method (incipient-wetness method) etc. are mentioned.

  By reacting the carbon-containing raw material with carbon dioxide in the presence of the catalyst as described above, or by reacting the carbon-containing raw material with steam (water vapor) and carbon dioxide, the synthesis gas used in the present invention is produced. Can be manufactured.

In the case of a method of reacting a carbon-containing raw material and carbon dioxide (CO ₂ reforming), the reaction temperature is 500 to 1200 ° C, preferably 600 to 1000 ° C. The reaction pressure is 5 to 40 kg / cm ² G, preferably 5 to 30 kg / cm ² G. When performing the reaction in a fixed bed system, a gas hourly space velocity (GHSV) is 1,000~10,000hr ^-1, 2,000~8,000hr ^-1 are preferred. The content of CO _{2 in} the raw material gas introduced into the reactor is _{20 to} 0.5 mol of CO ₂ per 1 mol of carbon in the carbon-containing raw material, and preferably 10 to 1 mol.

When a synthesis gas is produced by reacting a mixture of steam and CO ₂ with a carbon-containing raw material, the mixing ratio of steam and CO ₂ is not particularly limited, but usually the H ₂ O / CO ₂ (molar ratio) is 0. 1-10.

  In this synthesis gas production method, the energy required for the reforming reaction is caused by partial oxidation (partial combustion) of the carbon-containing raw material that is the reaction raw material for reforming, and the combustion heat generated at that time. To be replenished.

The partial oxidation reaction of the carbon-containing raw material is performed under conditions of a temperature of 600 to 1500 ° C., preferably 700 to 1300 ° C., and a pressure of 5 to 50 kg / cm ² G, preferably 10 to 40 kg / cm ² G. Oxygen is used as an oxidizing agent for partially oxidizing the carbon-containing raw material. As this oxygen source, oxygen-containing gas such as air or oxygen-enriched air is used in addition to pure oxygen. The content of oxygen in the raw material gas introduced into the reactor is 0.1 to 4, preferably 0.5 to 2, in terms of the atomic ratio (O / C) of oxygen to carbon in the carbon-containing raw material.

  By this partial oxidation of the carbon-containing raw material, a high-temperature mixed gas containing at least 600 ° C., preferably 700 to 1300 ° C., containing the unreacted carbon-containing raw material is obtained. A synthesis gas can be produced by reacting carbon dioxide or carbon dioxide and steam under the above conditions with the unreacted carbon-containing raw material in the mixed gas. Carbon dioxide or carbon dioxide and steam may be added to and reacted with the mixed gas obtained by partial oxidation of the carbon-containing raw material, or added and mixed in advance with the carbon-containing raw material used for the partial oxidation reaction. It may be left. In the latter case, the partial oxidation of the carbon-containing raw material and the reforming reaction can be performed simultaneously.

  The reforming reaction of the carbon-containing raw material can be carried out in various types of reactors, but usually it is preferably carried out in a fixed bed system or a fluidized bed system.

[Dimethyl ether production process]
In the dimethyl ether production process, by reacting carbon monoxide and hydrogen in the presence of a catalyst for dimethyl ether production, the synthesis gas produced from the synthesis gas obtained in the above synthesis gas production process contains dimethyl ether and carbon dioxide. Manufacturing.

  The gas fed into the reactor in the dimethyl ether production process may be a gas obtained by adding carbon monoxide, hydrogen, and other components to the synthesis gas obtained in the synthesis gas production process.

  Further, the gas fed into the reactor in the dimethyl ether production process may be a gas obtained by separating predetermined components from the synthesis gas obtained in the synthesis gas production process. Usually, the synthesis gas obtained in the synthesis gas production process is separated from moisture by a known method such as gas-liquid separation after cooling, and then cooled and separated by gas-liquid separation, absorption separation with amines, etc. After carbon dioxide is separated by a known method, it is sent to the reactor. Moreover, you may isolate | separate an unreacted carbon-containing raw material from the synthesis gas obtained in the synthesis gas manufacturing process.

  The water, carbon dioxide and unreacted carbon-containing raw material separated here can be recycled to the synthesis gas production process.

  In this dimethyl ether production process, a synthesis reaction of dimethyl ether can be performed according to a known method. For example, a dimethyl ether synthesis reaction product gas containing dimethyl ether and carbon dioxide can be produced by reacting carbon monoxide and hydrogen in the presence of a catalyst for producing dimethyl ether by the following method.

  The synthesis reaction of dimethyl ether can be carried out in various types of reactors such as a fixed bed type, a fluidized bed type and a slurry bed type, but it is usually preferred to carry out in a slurry bed type. In the case of the slurry bed type, the temperature in the reactor becomes more uniform, and the amount of by-products produced becomes smaller.

  Examples of the catalyst for producing dimethyl ether include a catalyst containing one or more methanol synthesis catalyst components and one or more methanol dehydration catalyst components, or one or more methanol synthesis catalyst components and one or more methanol dehydration catalyst components. And a catalyst containing at least one water gas shift catalyst component.

Here, the methanol synthesis catalyst component refers to a component that exhibits a catalytic action in the reaction of CO + 2H ₂ → CH ₃ OH. Further, the methanol dehydration catalyst component refers to one that exhibits a catalytic action in the reaction of 2CH ₃ OH → CH ₃ OCH ₃ + H ₂ O. The water gas shift catalyst component refers to a component that exhibits a catalytic action in the reaction of CO + H ₂ O → H ₂ + CO ₂ .

  As the methanol synthesis catalyst component, known methanol synthesis catalysts, specifically, copper oxide-zinc oxide, zinc oxide-chromium oxide, copper oxide-zinc oxide-chromium oxide, copper oxide-zinc oxide-alumina, zinc oxide- Examples thereof include chromium oxide-alumina. In the case of copper oxide-zinc oxide or copper oxide-zinc oxide-alumina, the content ratio of zinc oxide to copper oxide (zinc oxide / copper oxide; mass basis) is about 0.05 to 20, and about 0.1 to 5 In addition, the content ratio of alumina to copper oxide (alumina / copper oxide; mass basis) is about 0 to 2, and more preferably about 0 to 1. In the case of zinc oxide-chromium oxide or zinc oxide-chromium oxide-alumina, the content ratio of chromium oxide to zinc oxide (chromium oxide / zinc oxide; mass basis) is about 0.1 to 10, about 0.5 to 5 Moreover, the content ratio of alumina to zinc oxide (alumina / zinc oxide; mass basis) is about 0 to 2, and more preferably about 0 to 1.

The methanol synthesis catalyst component usually exhibits a catalytic action in a reaction of CO + H ₂ O → H ₂ + CO ₂ and can also serve as a water gas shift catalyst component.

  Examples of the methanol dehydration catalyst component include γ-alumina, silica, silica / alumina, and zeolite, which are acid-base catalysts. Examples of the metal oxide component of zeolite include alkali metal oxides such as sodium and potassium, and alkaline earth metal oxides such as calcium and magnesium.

  Examples of the water gas shift catalyst component include copper oxide-zinc oxide and iron oxide-chromium oxide. In the case of copper oxide-zinc oxide, the content ratio of copper oxide to zinc oxide (copper oxide / zinc oxide; based on mass) is about 0.1 to 20, and more preferably about 0.5 to 10. In the case of iron oxide-chromium oxide, the content ratio of chromium oxide to iron oxide (chromium oxide / iron oxide; mass basis) is about 0.1 to 20, more preferably about 0.5 to 10. Examples of the water gas shift catalyst component that also serves as the methanol dehydration catalyst component include copper (including copper oxide) -alumina.

  The content ratio of the methanol synthesis catalyst component, the methanol dehydration catalyst component, and the water gas shift catalyst component is not particularly limited, and can be appropriately determined according to the type of each catalyst component, reaction conditions, and the like. Usually, the content ratio of the methanol dehydration catalyst component to the methanol synthesis catalyst component (methanol dehydration catalyst component / methanol synthesis catalyst component; mass basis) is about 0.1 to 5, and more preferably about 0.2 to 2. The content ratio of the water gas catalyst component to the methanol synthesis catalyst component (water gas catalyst component / methanol synthesis catalyst component; mass basis) is about 0.2 to 5, more preferably about 0.5 to 3. When the methanol synthesis catalyst component also serves as the water gas shift catalyst component, the total amount of the methanol synthesis catalyst component and the content of the water gas shift catalyst component is the content of the methanol synthesis catalyst component. Is preferred.

  The catalyst for producing dimethyl ether is preferably a mixture of a methanol synthesis catalyst component, a methanol dehydration catalyst component, and, if necessary, a water gas shift catalyst component. After these catalyst components are uniformly mixed, they may be molded as necessary, or may be pulverized again after molding. Even better catalytic performance may be obtained by uniformly mixing the catalyst components, press-contacting them, and then re-pulverizing the catalyst.

  When using a slurry bed reactor, the average particle size of the methanol synthesis catalyst component, the average particle size of the methanol dehydration catalyst component, and the average particle size of the water gas shift catalyst component are preferably 300 μm or less, more preferably 1 to 200 μm, 10-150 micrometers is especially preferable.

  The catalyst for producing dimethyl ether may contain other additive components as necessary within the range not impairing the desired effect.

  In the dimethyl ether production process, carbon monoxide and hydrogen are reacted using the above catalyst to produce dimethyl ether.

  As described above, the reaction is preferably performed using a slurry bed reactor.

  When a slurry bed reactor is used, the catalyst for producing dimethyl ether is used in a state of being dispersed in a medium oil as a solvent and slurryed.

  As a medium oil, it is necessary to be able to stably maintain a liquid state under reaction conditions, for example, aliphatic, aromatic or alicyclic hydrocarbons, alcohols, ethers, esters, ketones, and halides thereof. Etc. One medium oil may be used, or two or more medium oils may be mixed and used. As medium oil, what has a hydrocarbon as a main component is preferable. As the medium oil, light oil from which sulfur content has been removed, vacuum gas oil, hydrotreated coal tar high boiling fraction, Fischer-Tropsch synthetic oil, high boiling food oil, and the like can also be used.

  The amount of the dimethyl ether production catalyst can be appropriately determined according to the type of the solvent (medium oil) to be used, reaction conditions, and the like, but is usually preferably about 1 to 50% by weight based on the solvent. The amount of the catalyst for producing dimethyl ether is more preferably 5% by weight or more, particularly preferably 10% by weight or more based on the solvent. The amount of the dimethyl ether production catalyst is more preferably 40% by weight or less based on the solvent.

The gas fed into the reactor preferably contains carbon monoxide and hydrogen at CO: H ₂ = 1: 0.5 to 1: 1.5 (molar ratio). The content ratio of hydrogen to carbon monoxide (H ₂ / CO; on a molar basis) in the gas fed to the reactor is more preferably 0.8 or more, and particularly preferably 0.9 or more. Further, the content ratio of hydrogen to carbon monoxide (H ₂ / CO; on a molar basis) in the gas fed to the reactor is more preferably 1.2 or less, and particularly preferably 1.1 or less.

  The gas fed into the reactor may contain components other than carbon monoxide and hydrogen.

  When a slurry bed reactor is used, the reaction temperature is preferably 150 to 400 ° C, more preferably 200 ° C or more, and more preferably 350 ° C or less. By setting the reaction temperature within the above range, the conversion rate of carbon monoxide becomes higher.

  The reaction pressure is preferably 1 to 30 MPa, more preferably 2 MPa or more, and more preferably 8 MPa or less. By setting the reaction pressure to 1 MPa or more, the conversion rate of carbon monoxide becomes higher. On the other hand, the reaction pressure is preferably 30 MPa or less from the viewpoint of economy.

  The space velocity (feeding rate of the raw material gas per kg of catalyst) is preferably 100 to 50000 L / kg · h, more preferably 500 L / kg · h or more, and more preferably 30000 L / kg · h or less. By setting the space velocity to 50000 L / kg · h or less, the conversion rate of carbon monoxide becomes higher. On the other hand, the space velocity is preferably 100 L / kg · h or more from the viewpoint of economy.

  The dimethyl ether synthesis reaction product gas thus obtained usually contains, in addition to dimethyl ether and carbon dioxide, unreacted raw materials such as carbon monoxide and hydrogen, water, methanol, and the like.

[Separation process]
In the separation step, a carbon dioxide-containing gas containing carbon dioxide and a dimethyl ether-containing gas containing dimethyl ether as a main component are separated from the dimethyl ether synthesis reaction product gas obtained in the dimethyl ether production step.

  Before separation of carbon dioxide-containing gas or after separation of carbon dioxide-containing gas, if necessary, from dimethyl ether synthesis reaction product gas or dimethyl ether-containing gas, by-product moisture and methanol, unreacted raw material Carbon monoxide and hydrogen may be separated.

  Moreover, you may further isolate | separate components other than a carbon dioxide from the carbon dioxide containing gas isolate | separated from the dimethyl ether synthesis reaction product gas as needed.

  The carbon dioxide-containing gas may contain components other than carbon dioxide.

  Separation of the carbon dioxide-containing gas can be performed by a known method such as gas-liquid separation after cooling, absorption separation with amine or the like, distillation, and the like.

  The separation of moisture can be performed by a known method such as gas-liquid separation after cooling.

  Separation of methanol can be performed by a known method such as gas-liquid separation after cooling or absorption separation.

  In addition, moisture and methanol can be simultaneously separated from the dimethyl ether synthesis reaction product gas or the dimethyl ether-containing gas by gas-liquid separation after cooling.

  The carbon monoxide can be separated by a known method such as gas-liquid separation after cooling.

  Hydrogen can be separated by a known method such as gas-liquid separation after cooling.

  Further, carbon monoxide and hydrogen can be simultaneously separated from the dimethyl ether synthesis reaction product gas or the dimethyl ether-containing gas by gas-liquid separation after cooling.

  The water, carbon monoxide, and hydrogen separated here can be recycled to the synthesis gas production process. In addition, the carbon monoxide and hydrogen separated here can be recycled to the dimethyl ether production process. The separated methanol can be used as a raw material for an olefin production process or a liquefied petroleum gas production process, which will be described later, and hydrogen can be used as a raw material for an olefin hydrogenation process or a liquefied petroleum gas production process, which will be described later.

[Recycling process]
In the recycling step, the carbon dioxide-containing gas separated from the dimethyl ether synthesis reaction product gas in the separation step is recycled to the synthesis gas production step (reforming step).

  The carbon dioxide-containing gas separated from the dimethyl ether synthesis reaction product gas may all be recycled to the synthesis gas production process, or a part may be extracted out of the system and the rest may be recycled to the synthesis gas production process. . The carbon dioxide-containing gas can be separated into only the desired component, that is, carbon dioxide, and recycled to the synthesis gas production process.

  In order to recycle the carbon dioxide-containing gas, a known technique such as appropriately providing a pressure increasing means in the recycle line can be employed.

[Manufacturing process of liquefied petroleum gas from dimethyl ether-containing gas]
In the present invention, liquefied petroleum gas (LPG) containing a hydrocarbon whose main component is propane or butane is produced from the dimethyl ether-containing gas thus obtained.

  In the production method of the 1-1 LPG and the production method of the 1-2 LPG of the present invention (both are also referred to as the production method of the first LPG), the synthesis reaction of olefin from dimethyl ether and the olefin Separated from the hydrogenation reaction to paraffin, LPG is synthesized in two steps. On the other hand, in the second LPG production method of the present invention, LPG is synthesized from dimethyl ether in one step.

  Next, an olefin production step and an olefin hydrogenation step in the first LPG production method, and a liquefied petroleum gas production step in the second LPG production method, which are steps for producing liquefied petroleum gas from dimethyl ether-containing gas explain.

[Olefin production process]
In the olefin production step of the first LPG production method, an olefin whose main component is propylene or butene from the dimethyl ether-containing gas obtained in the above separation step by reacting dimethyl ether in the presence of a catalyst for olefin production. Olefin-containing gas containing In addition, this olefin containing gas contains the by-product water other than olefins. Further, the olefin hydrogenation reaction proceeds in the olefin production process, and the resulting olefin-containing gas may contain paraffins such as propane and butane.

  The gas fed into the reactor in the olefin production process may be a gas obtained by adding other components such as methanol, hydrogen, water, etc. to the dimethyl ether-containing gas obtained in the separation process.

  Examples of the olefin production catalyst include zeolite that exhibits a catalytic action in the condensation reaction of methanol with hydrocarbons and / or the condensation reaction of dimethyl ether with hydrocarbons.

  In this olefin production process, it is considered that an olefin whose main component is propylene or butene is synthesized from dimethyl ether according to the following formula (3).

このオレフィンの生成過程においては、まず、ジメチルエーテルの水和によりメタノールが生成し、オレフィン製造用触媒であるゼオライトの細孔内の空間場に配座する酸点と塩基点との協奏作用により、メタノールの脱水によってカルベン（Ｈ_２Ｃ：）が生成する。そして、このカルベンの重合によって、主成分がプロピレンまたはブテンであるオレフィンが生成する。より詳細には、２量体としてエチレンが、３量体として、あるいは、エチレンとの反応によってプロピレンが、４量体として、あるいは、プロピレンとの反応によって、あるいは、エチレンの２量化によってブテンが生成すると考えられる。

In this olefin production process, first, methanol is produced by hydration of dimethyl ether, and by the concerted action of the acid point and base point coordinated in the space field in the pores of the zeolite, which is a catalyst for olefin production, methanol Carbenes (H ₂ C :) are produced by dehydration of The carbene polymerization produces an olefin whose main component is propylene or butene. More specifically, ethylene is produced as a dimer, but as a trimer, or by reaction with ethylene, propylene is produced as a tetramer, by reaction with propylene, or by dimerization of ethylene. I think that.

  In this olefin production process, dimethyl ether is produced by dehydration dimerization of methanol, carbene is produced by decomposition of ethylene, etc., higher olefin is produced by polymerization of lower olefin, higher olefin is decomposed, olefin cyclization, isomerization Reactions such as the formation of aromatic hydrocarbons, conjugated hydrocarbon compounds and saturated hydrocarbons, and tar or coking of conjugated hydrocarbon compounds having a cyclopentadienyl structure are considered to occur.

  In the present invention, among the reactions described above, a production reaction of an olefin having a carbon number corresponding to the target LPG or a precursor thereof, that is, a carbene production reaction, or a production of lower olefins such as ethylene, propylene and butene by carbene polymerization. It is important to suppress reactions other than the reaction, the reaction of carbene with ethylene or propylene, the dimerization reaction of ethylene, and the decomposition of higher olefins. Furthermore, it is important to control the reaction so that the main component of the olefins produced is propylene or butene.

  For that purpose, it is important to use a zeolite having an appropriate acid strength, acid amount (acid concentration) and pore diameter as a catalyst for olefin production.

  Examples of the olefin production catalyst include ZSM-34 and ZSM-5, preferably high silica ZSM-5 having a Si / Al ratio (atomic ratio) of 100 or less, and silicoaluminophosphate (SAPO) such as SAPO-34. Etc. Further, the metal containing Ni, Co, Fe, Pt, Pd, Cu, Ag, or the like, or an element such as Mg, P, lanthanide, or ion-exchanged with these metals, elements, Ti, Nb, or the like. There are also mentioned zeolites. It is possible to adjust the acid strength and the acid amount of the zeolite by containing a metal or a compound, or by ion exchange with a metal or a compound, or by depositing coke. Moreover, the acid strength and acid amount of the zeolite can be adjusted not only on average but separately, for example, outside the zeolite pores, near the pore inlet, and inside the pores. Furthermore, the pore diameter can be finely adjusted simultaneously with or separately from the adjustment of the acid strength and the acid amount. In addition, a metal or a compound can be contained, or ion exchange can be performed with a metal or a compound, and coke can be deposited.

  As the olefin production catalyst, among them, high silica ZSM-5 and SAPO-34 are preferable, and ZSM-5 having an Si / Al ratio (atomic ratio) of 100 or less, more preferably 20 or more and 70 or less, or this skeleton. A metallosilicate having an MFI structure in which less than half of Al is substituted with Fe is more preferable.

  In addition, the catalyst for olefin production may use 1 type, or may use 2 or more types together. Moreover, the catalyst for olefin production may contain other additive components as long as the desired effect is not impaired. For example, the catalyst can be diluted with quartz sand or the like. If the reaction can be controlled so that the main component of the olefins to be produced is propylene or butene, the catalyst layer containing the olefin production catalyst contains one or more olefin hydrogenation catalysts. You may do it.

  When the reaction is carried out in a fixed bed, the composition of the catalyst layer containing the olefin production catalyst can be changed with respect to the flow direction of the raw material gas.

  The catalyst for olefin production may be a catalyst provided with an olefin hydrogenation catalyst function. As such, the zeolite, which is an olefin production catalyst, is modified with a metal such as Fe, Ni, Pd, Pt, etc., which is an olefin hydrogenation catalyst component (support, ion exchange, skeletal substitution, or these metals). And a catalyst in which components are separately supported on a carrier and mixed).

  In order for the main component of the olefins to be produced to be propylene or butene, it is also important to control the reaction conditions, particularly the contact time between the feed gas and the olefin production catalyst. Olefin production reactions such as carbene polymerization and olefin polymerization are sequential reactions, and as the contact time between the raw material gas and the catalyst for olefin production increases, an olefin having a higher carbon number tends to be obtained.

  The contact time between the raw material gas from which olefins mainly composed of propylene or butene are obtained and the olefin production catalyst varies depending on the type of catalyst used and other reaction conditions. In the present invention, the contact time between the raw material gas and the catalyst for olefin production can be determined by conducting an olefin synthesis reaction in advance.

  Further, in the olefin hydrogenation step described later, the catalyst layer containing the olefin hydrogenation catalyst may contain an olefin production catalyst, but in that case, also in the catalyst layer containing the olefin hydrogenation catalyst. In consideration of the progress of reactions such as carbene polymerization and olefin polymerization, the generation reaction of olefins having a larger number of carbon atoms, that is, the elimination reaction of olefins having a carbon number equivalent to the target LPG does not proceed. It is necessary to determine the contact time between the feed gas and the olefin production catalyst.

  The reaction can be carried out in a fixed bed, a fluidized bed or a moving bed. When two or more catalyst layers are provided, it is preferable to use a fixed bed. Reaction conditions such as the raw material gas composition, reaction temperature, reaction pressure, and contact time with the catalyst can be appropriately determined according to the type, performance, shape, etc. of the catalyst used.

  For example, when proton type ZSM-5 zeolite is used as a catalyst for olefin production, the reaction can be carried out under the following conditions.

  The gas fed into the reactor contains the dimethyl ether-containing gas obtained in the above separation step. Moreover, the gas sent into the reactor may further contain hydrogen.

  In the case of the 1-2 LPG production method in which hydrogen is added to the dimethyl ether-containing gas in the olefin production process, the concentration of hydrogen in the gas fed into the reactor is preferably 2 mol or more per 1 mol of dimethyl ether. 2.5 moles or more is more preferable. In this case, the concentration of hydrogen in the gas fed into the reactor is preferably 5 mol or less, more preferably 4 mol or less, with respect to 1 mol of dimethyl ether.

  In the case of the 1-2 LPG production method, the concentration of dimethyl ether in the gas fed into the reactor is preferably 10 mol% or more, more preferably 20 mol% or more. In this case, the concentration of dimethyl ether in the gas fed to the reactor is preferably 40 mol% or less, and more preferably 30 mol% or less.

  The gas fed into the reactor may contain, for example, methanol, water, inert gas, etc., in addition to dimethyl ether and hydrogen which are reaction raw materials. Methanol is also a reaction raw material and reacts in the presence of an olefin production catalyst to produce olefins.

  When hydrogen is added to the dimethyl ether-containing gas, the dimethyl ether-containing gas and hydrogen (hydrogen-containing gas) may be mixed and supplied to the reactor, or may be separately supplied to the reactor.

  The reactor inlet temperature is preferably 300 ° C or higher, more preferably 320 ° C or higher, from the viewpoint of activity. Further, the reactor inlet temperature is preferably 470 ° C. or lower, more preferably 450 ° C. or lower, from the viewpoints of selectivity and catalyst life.

  The reaction pressure is preferably 0.1 MPa or more, more preferably 0.13 MPa or more, from the viewpoint of activity, selectivity, and operability of the apparatus. Further, the reaction pressure is preferably 2 MPa or less, more preferably 0.99 MPa or less, from the viewpoints of economy and safety.

Gas space velocity, in terms of economic efficiency, preferably 2000 hr ^-1 or more, 4000 hr ^-1 or more is more preferable. Further, the gas space velocity, in terms of activity and selectivity, preferably 60000Hr ^-1 or less, 30000 hr ^-1 or less is more preferable.

  The gas fed into the reactor can be divided and fed into the reactor, thereby controlling the reaction temperature.

  The reaction can be carried out in a fixed bed, a fluidized bed, a moving bed, etc., but it is preferable to select from both aspects of control of reaction temperature and catalyst regeneration method. For example, as a fixed bed, a quench reactor such as an internal multi-stage quench system, a multi-tube reactor, a multi-stage reactor including a plurality of heat exchangers, a multi-stage cooling radial flow system or a double-tube heat exchange Other reactors such as a system, a built-in cooling coil system, and a mixed flow system can be used.

  The catalyst for olefin production can be diluted with silica, alumina, or an inert and stable heat conductor for the purpose of temperature control. Moreover, the catalyst for olefin production can also be applied to the heat exchanger surface for the purpose of temperature control.

[Olefin hydrogenation process]
In the olefin hydrogenation step of the first LPG production method, the main component is obtained from the olefin-containing gas obtained in the olefin production step by reacting olefin and hydrogen in the presence of the olefin hydrogenation catalyst. Producing liquefied petroleum gas (LPG) containing hydrocarbons that are propane or butane.

  In the case of the 1-1st LPG manufacturing method, hydrogen is added to the olefin-containing gas obtained in the olefin manufacturing step, and the resultant is sent to the reactor. In the case of the 1-2 LPG production method, the olefin-containing gas obtained in the olefin production step contains hydrogen, but if necessary, hydrogen may be further added and fed to the reactor.

  In this olefin hydrogenation step, propylene and hydrogen are reacted according to the following formula (4) to produce propane, and butene and hydrogen are reacted according to the following formula (5) to produce butane.

オレフィン水素化用触媒としては、公知の水素化触媒、具体的には、Ｆｅ，Ｃｏ，Ｎｉ，Ｒｕ，Ｒｈ，Ｐｄ，Ｏｓ，Ｉｒ，Ｐｔ，Ｃｕ，Ｒｅ等の金属または合金、Ｃｕ，Ｃｏ，Ｎｉ，Ｃｒ，Ｚｎ，Ｒｅ，Ｍｏ，Ｗ等の金属の酸化物、Ｃｏ，Ｒｅ，Ｍｏ，Ｗ等の金属の硫化物などが挙げられる。また、これらの触媒をカーボン、シリカ、アルミナ、シリカ・アルミナ、ゼオライト等の担体に担持して、あるいは、これらと混合して用いることもできる。

As the olefin hydrogenation catalyst, a known hydrogenation catalyst, specifically, a metal or alloy such as Fe, Co, Ni, Ru, Rh, Pd, Os, Ir, Pt, Cu, Re, Cu, Co, Examples thereof include oxides of metals such as Ni, Cr, Zn, Re, Mo, and W, and sulfides of metals such as Co, Re, Mo, and W. Further, these catalysts can be used by supporting them on a carrier such as carbon, silica, alumina, silica / alumina, zeolite, or a mixture thereof.

  As the olefin hydrogenation catalyst, a nickel catalyst, a palladium catalyst, a platinum catalyst and the like are preferable.

  In addition, the catalyst for olefin hydrogenation may use 1 type, or may use 2 or more types together. Moreover, the catalyst for olefin hydrogenation may contain other additive components within a range not impairing the desired effect. For example, the catalyst can be diluted with quartz sand or the like. The catalyst layer containing the olefin hydrogenation catalyst may contain one or more olefin production catalysts.

  When the reaction is carried out in a fixed bed, the composition of the catalyst layer containing the olefin hydrogenation catalyst can be changed with respect to the flow direction of the raw material gas.

  The catalyst for olefin hydrogenation may be a catalyst provided with a catalyst function for olefin production. This is the same as the olefin production catalyst provided with the olefin hydrogenation catalyst function.

  The reaction can be carried out in a fixed bed, a fluidized bed or a moving bed. When two or more catalyst layers are provided, it is preferable to use a fixed bed. The reaction conditions such as the raw material gas composition, reaction temperature, reaction pressure, and contact time with the catalyst can be appropriately determined according to a known method according to the type, performance, shape, etc. of the catalyst used.

  For example, when Pd-alumina (palladium-supported alumina) is used as the olefin hydrogenation catalyst, the reaction can be performed under the following conditions.

  In the case of the 1-1st LPG manufacturing method, the gas sent into the reactor contains the olefin-containing gas and hydrogen obtained in the olefin manufacturing step. In the case of the 1-2 LPG production method, the gas fed into the reactor contains the olefin-containing gas obtained in the olefin production process. Also in this case, the gas fed into the reactor may further be a gas obtained by adding hydrogen to an olefin-containing gas.

The content ratio of hydrogen to olefin (mainly propylene and butene) (H ₂ / C _n H _2n ; molar basis) in the gas fed to the reactor is as follows: 1 or more is preferable, and 1.5 or more is more preferable. In addition, the content ratio of hydrogen to olefin (mainly propylene and butene) in the gas fed to the reactor (H ₂ / C _n H _2n ; molar basis) is preferably 10 or less from the viewpoint of economy, 5 or less is more preferable.

  The gas fed into the reactor may contain, for example, water, an inert gas, etc. in addition to the olefin-containing gas and hydrogen.

  The olefin-containing gas and hydrogen (hydrogen-containing gas) obtained in the olefin production process may be mixed and supplied to the reactor, or may be separately supplied to the reactor. Further, the gas fed into the reactor may be divided and fed into the reactor.

  The reaction temperature is preferably 120 ° C or higher, more preferably 140 ° C or higher, from the viewpoint of activity. The reaction temperature is preferably 400 ° C. or less, more preferably 350 ° C. or less, from the viewpoint of selectivity and removal of reaction heat.

  The reaction pressure is preferably 0.11 MPa or more, more preferably 0.13 MPa or more from the viewpoint of activity. In addition, the reaction pressure is preferably 3 MPa or less, more preferably 2 MPa or less, from the viewpoint of economy and safety.

Gas space velocity, in terms of economic efficiency, preferably 1000 hr ^-1 or more, 1500 hr ^-1 or more is more preferable. Further, the gas space velocity, in terms of activity, preferably 40000Hr ^-1 or less, 20000Hr ^-1 or less is more preferable.

  In the reaction product gas (lower paraffin-containing gas) obtained in this way, the main component of the contained hydrocarbon is propane or butane. From the viewpoint of liquefaction characteristics, the higher the total content of propane and butane in the lower paraffin-containing gas, the better.

  Further, the obtained lower paraffin-containing gas preferably has more propane than butane from the viewpoint of combustibility and vapor pressure characteristics.

  In addition, the obtained lower paraffin-containing gas usually contains moisture, a low-boiling component that is a substance having a boiling point or sublimation point lower than that of propane, and a high-boiling component that is a substance having a boiling point higher than that of butane. It is. Examples of the low boiling point component include hydrogen as an unreacted raw material, ethane as a by-product, methane, carbon monoxide, and carbon dioxide. Examples of the high-boiling component include high-boiling paraffins (pentane, hexane, etc.) that are by-products.

  Therefore, moisture, a low boiling point component, a high boiling point component, etc. are isolate | separated from the obtained lower paraffin containing gas as needed, and liquefied petroleum gas (LPG) which has propane or butane as a main component is obtained. If necessary, dimethyl ether, which is an unreacted raw material, is also separated by a known method.

  Separation of moisture, low-boiling components, and high-boiling components can be performed by known methods.

  Separation of moisture can be performed, for example, by liquid-liquid separation.

  Separation of low-boiling components can be performed, for example, by gas-liquid separation, absorption separation, distillation or the like. More specifically, it can be carried out by gas-liquid separation or absorption separation at pressurized normal temperature, gas-liquid separation or absorption separation after cooling, or a combination thereof. Moreover, it can also carry out by membrane separation or adsorption separation, and can also carry out by the combination of these, gas-liquid separation, absorption separation, and distillation. For the separation of low-boiling components, a gas recovery process commonly used in refineries (“Petroleum Refining Process”, Petroleum Society / Ed., Kodansha Scientific, 1998, p.28-p.32) is applied. be able to.

  As a method for separating the low-boiling components, an absorption process in which liquefied petroleum gas mainly composed of propane or butane is absorbed in an absorbing liquid such as high-boiling paraffin gas having a boiling point higher than butane or gasoline is preferable.

  Separation of high-boiling components can be performed, for example, by gas-liquid separation, absorption separation, distillation, or the like.

  The separation conditions can be appropriately determined according to a known method.

  Moreover, in order to obtain liquefied petroleum gas, you may pressurize and / or cool as needed.

  For consumer use, from the viewpoint of safety at the time of use, for example, the content of low-boiling components in LPG is preferably 5 mol% or less (including 0 mol%) by separation.

  In addition, the low boiling point component separated from the lower paraffin-containing gas in the olefin hydrogenation step can be recycled as a raw material for the synthesis gas production step.

  All the low-boiling components separated from the lower paraffin-containing gas may be recycled to the synthesis gas production process, or a part may be extracted out of the system and the rest may be recycled to the synthesis gas production process. As for the low boiling point component, only a desired component can be separated and recycled to the synthesis gas production process.

  In this case, in the synthesis gas production process, the content of low-boiling components in the gas fed to the reformer, which is a reactor, that is, the content of the recycled material can be determined as appropriate.

  In order to recycle the low boiling point component, a known technique such as appropriately providing a pressure raising means in the recycle line can be employed.

  According to the first LPG production method of the present invention, LPG whose main component is propane or butane, specifically, the total content of propane and butane is 90% or more, more preferably 95% or more on the basis of carbon content ( LPG can also be produced.

  In addition, according to the first LPG production method of the present invention, LPG whose main component is propane, specifically, the content of propane is 50% or more, further 60% or more, further 90 % LPG (including 100%) can be produced. According to the first LPG production method of the present invention, it is possible to produce LPG having a composition suitable for propane gas that is widely used as a fuel for household and business use.

[Liquefied petroleum gas production process]
In the liquefied petroleum gas production step of the second LPG production method, dimethyl ether and hydrogen are reacted in the presence of a liquefied petroleum gas production catalyst, thereby allowing the dimethyl ether-containing gas and hydrogen obtained in the above separation step to react with each other. , Producing liquefied petroleum gas (LPG) containing hydrocarbons whose main component is propane or butane. In addition, when the dimethyl ether containing gas obtained in said separation process contains the quantity of hydrogen required for LPG synthesis reaction with dimethyl ether, it is not necessary to add hydrogen to a dimethyl ether containing gas.

  The gas fed into the reactor in the liquefied petroleum gas production process may be a gas obtained by adding other components such as methanol to the dimethyl ether-containing gas and hydrogen obtained in the separation process.

  As a catalyst for liquefied petroleum gas production, for example, a catalyst in which an olefin hydrogenation catalyst component is supported on zeolite, a catalyst containing one or more methanol synthesis catalyst components and one or more zeolite catalyst components, specifically, , Cu—Zn-based methanol synthesis catalyst and USY-type zeolite in a Cu—Zn-based methanol synthesis catalyst: USY-type zeolite = 1: 5 to 2: 1 (mass ratio), Cu—Zn-based methanol synthesis catalyst And β-zeolite, a catalyst containing Cu-Zn-based methanol synthesis catalyst: β-zeolite = 1: 5 to 2: 1 (mass ratio), Pd-based methanol synthesis catalyst and β-zeolite, Pd-based methanol Synthesis catalyst: β-zeolite = 1: 5 to 2.5: 1 (mass ratio), etc. In addition, a catalyst containing a hydrogenation catalyst such as supported Fe, Co, or Ni and a USY-type zeolite, a catalyst containing a hydrogenation catalyst such as supported Fe, Co, or Ni and β-zeolite, or the like may also be used.

  Here, an olefin hydrogenation catalyst component refers to what shows a catalytic action in the hydrogenation reaction of an olefin to paraffin. Here, the zeolite exhibits a catalytic action in the condensation reaction of methanol to hydrocarbon and / or the condensation reaction of dimethyl ether to hydrocarbon.

Here, the methanol synthesis catalyst component refers to a component that exhibits a catalytic action in the reaction of CO + 2H ₂ → CH ₃ OH. The zeolite catalyst component refers to a zeolite that exhibits a catalytic action in the condensation reaction of methanol to hydrocarbons and / or the condensation reaction of dimethyl ether to hydrocarbons. In the above catalyst containing a methanol synthesis catalyst component and a zeolite catalyst component, the methanol synthesis catalyst component functions as an olefin hydrogenation catalyst component.

  In this liquefied petroleum gas production process, it is considered that paraffin (LPG) whose main component is propane or butane is synthesized from dimethyl ether and hydrogen according to the following formula (6).

本発明においては、まず、ジメチルエーテルの水和によりメタノールが生成し、ゼオライト触媒成分の細孔内の空間場に配座する酸点と塩基点との協奏作用により、メタノールの脱水によってカルベン（Ｈ_２Ｃ：）が生成する。そして、このカルベンの重合によって、主成分がプロピレンまたはブテンであるオレフィンが生成する。より詳細には、２量体としてエチレンが、３量体として、あるいは、エチレンとの反応によってプロピレンが、４量体として、あるいは、プロピレンとの反応によって、あるいは、エチレンの２量化によってブテンが生成すると考えられる。

In the present invention, first, methanol is produced by hydration of dimethyl ether, and carbene (H _{2) is produced} by dehydration of methanol by the concerted action of acid sites and base sites that conform to the space field in the pores of the zeolite catalyst component. C :) is generated. The carbene polymerization produces an olefin whose main component is propylene or butene. More specifically, ethylene is produced as a dimer, but as a trimer, or by reaction with ethylene, propylene is produced as a tetramer, by reaction with propylene, or by dimerization of ethylene. I think that.

  Further, it is considered that a reaction such as the production of dimethyl ether by dehydration dimerization of methanol occurs in the process of producing the olefin.

  And the produced | generated olefin is hydrogenated by the effect | action of an olefin hydrogenation catalyst component, and the paraffin, ie, LPG, whose main component is propane or butane is synthesize | combined.

  In the above catalyst, any known Cu—Zn-based methanol synthesis catalyst can be used, and a commercially available product can also be used. Examples of the Pd-based methanol synthesis catalyst include those in which 0.1 to 10% by weight of Pd is supported on a carrier such as silica, 0.1 to 10% by weight of Pd on a carrier such as silica, and an alkali metal such as Ca. And at least one selected from the group consisting of alkaline earth metals and lanthanoid metals is supported by 5% by weight or less (excluding 0% by weight).

  In addition, the catalyst for liquefied petroleum gas manufacture may use 1 type, or may use 2 or more types together. Moreover, the catalyst for liquefied petroleum gas production may contain other additive components within the range not impairing the desired effect. For example, the catalyst can be diluted with quartz sand or the like.

  When the reaction is performed in a fixed bed, the composition of the catalyst layer containing the liquefied petroleum gas production catalyst can be changed with respect to the flow direction of the raw material gas. For example, the catalyst layer may be configured to contain a large amount of a zeolite catalyst component in the preceding stage and a large amount of a methanol synthesis catalyst component having a function as an olefin hydrogenation catalyst component in the subsequent stage with respect to the flow direction of the raw material gas. it can.

  As the liquefied petroleum gas production catalyst, a catalyst in which an olefin hydrogenation catalyst component is supported on zeolite is particularly preferable.

  The olefin hydrogenation catalyst component is not particularly limited as long as it exhibits a catalytic action in the hydrogenation reaction of olefin to paraffin. Specific examples of the olefin hydrogenation catalyst component include Fe, Co, Ni, Cu, Zn, Ru, Rh, Pd, Ir, and Pt. The olefin hydrogenation catalyst component may be one kind or two or more kinds.

  Among these, as the olefin hydrogenation catalyst component, Pd and Pt are preferable, and Pd is more preferable. By using Pd and / or Pt as the olefin hydrogenation catalyst component, carbon monoxide and carbon dioxide by-products can be more sufficiently suppressed while maintaining a high yield of propane and butane.

  Note that Pd and Pt may not be included in the form of a metal, and may be included in the form of an oxide, nitrate, chloride, or the like. In this case, it is preferable to convert Pd and Pt to metallic palladium and metallic platinum by, for example, hydrogen reduction treatment before the reaction from the viewpoint that higher catalytic activity can be obtained.

  The treatment conditions for the reduction treatment for activating Pd and Pt can be appropriately determined according to the kind of the supported palladium compound and / or platinum compound.

  Further, from the viewpoint of catalytic activity, it is preferable that olefin hydrogenation catalyst components such as Pd and Pt are supported in a highly dispersed manner on zeolite.

  The total supported amount of the olefin hydrogenation catalyst component of the liquefied petroleum gas production catalyst in which the olefin hydrogenation catalyst component is supported on zeolite is preferably 0.005 wt% or more, more preferably 0.01 wt% or more, and 0 0.05% by weight or more is particularly preferable. Further, the supported amount of the olefin hydrogenation catalyst component of the liquefied petroleum gas production catalyst in which the olefin hydrogenation catalyst component is supported on zeolite is preferably 5% by weight or less in total from the viewpoint of dispersibility and economy. % By weight or less is more preferable, and 0.7% by weight or less is particularly preferable. Propane and / or butane can be produced with higher conversion, higher selectivity and higher yield by setting the supported amount of the olefin hydrogenation catalyst component in the liquefied petroleum gas production catalyst within the above range.

  By making the supported amount of the olefin hydrogenation catalyst component 0.005% by weight or more, more preferably 0.01% by weight or more, particularly preferably 0.05% by weight or more, methanol and / or dimethyl ether can be more selectively used. It can be converted to liquefied petroleum gas based on propane or butane. On the other hand, when the supported amount of the olefin hydrogenation catalyst component is 5% by weight or less, more preferably 1% by weight or less, and particularly preferably 0.7% by weight or less, higher catalytic activity can be obtained.

  The zeolite carrying the olefin hydrogenation catalyst component is not particularly limited as long as it shows a catalytic action in the condensation reaction of methanol with hydrocarbons and / or the condensation reaction of dimethyl ether with hydrocarbons. Moreover, what is marketed can also be used. Examples of the zeolite include ZSM-5, β-zeolite, and USY-type zeolite. Zeolite may be used alone or in combination of two or more.

  As the zeolite carrying the olefin hydrogenation catalyst component, it is important to use a zeolite having an appropriate acid strength, acid amount (acid concentration) and pore diameter. The Si / Al ratio (atomic ratio) of the zeolite is also important. In addition, pore structure, crystal size, and other factors appear to be important.

  Among them, ZSM-5 is preferable as the zeolite carrying the olefin hydrogenation catalyst component. By using ZSM-5, higher catalytic activity, higher propane and butane yields can be obtained, and carbon monoxide and carbon dioxide by-products can be more sufficiently suppressed.

  As ZSM-5 carrying the olefin hydrogenation catalyst component, high silica ZSM-5 is preferable, and specifically, ZSM-5 having a Si / Al ratio (atomic ratio) of 20 to 100 is preferable. By using ZSM-5 having an Si / Al ratio (atomic ratio) of 20 to 100, higher catalytic activity, higher yields of propane and butane are obtained, and carbon monoxide and carbon dioxide by-products are produced. It can suppress more fully. The Si / Al ratio (atomic ratio) of ZSM-5 is more preferably 70 or less, and particularly preferably 60 or less.

  As the liquefied petroleum gas production catalyst used in the present invention, a catalyst in which Pd and / or Pt is supported on ZSM-5 is particularly preferable, and a catalyst in which Pd is supported on ZSM-5 is more preferable.

  In this liquefied petroleum gas production catalyst, the total amount of Pd and / or Pt supported is preferably 0.005% by weight or more, more preferably 0.01% by weight or more, and particularly preferably 0.05% by weight or more. . The total amount of Pd and / or Pt supported is preferably 5% by weight or less, more preferably 1% by weight or less, and particularly preferably 0.7% by weight or less.

  The above liquefied petroleum gas production catalyst may be one in which components other than the olefin hydrogenation catalyst component are supported on zeolite within a range that does not impair the desired effect.

  A liquefied petroleum gas production catalyst in which an olefin hydrogenation catalyst component is supported on zeolite can be prepared by a known method such as an ion exchange method or an impregnation method. The catalyst for liquefied petroleum gas production prepared by the ion exchange method may have higher catalytic activity than the catalyst for liquefied petroleum gas production prepared by the impregnation method, and the LPG synthesis reaction may be performed at a lower reaction temperature. Higher hydrocarbon selectivity, and even higher propane and butane selectivity may be obtained.

  The zeolite carrying the olefin hydrogenation catalyst component is used after being pulverized and molded as necessary. Although it does not specifically limit as a shaping | molding method of a catalyst, A dry method is preferable, for example, an extrusion molding method, a tableting molding method, etc. are mentioned.

  The liquefied petroleum gas production catalyst may contain other additive components as necessary within the range not impairing the desired effect.

  In the liquefied petroleum gas production process, dimethyl ether and hydrogen are reacted using one or more catalysts for liquefied petroleum gas production as described above, and paraffins whose main component is propane or butane, preferably the main component is propane. Paraffins or LPG are produced.

  The reaction can be carried out in a fixed bed, a fluidized bed or a moving bed. Reaction conditions such as the raw material gas composition, reaction temperature, reaction pressure, and contact time with the catalyst can be appropriately determined according to the type of catalyst used. For example, the LPG synthesis reaction is performed under the following conditions. Can do.

  The gas fed into the reactor contains the dimethyl ether-containing gas obtained in the above separation step and hydrogen.

  The concentration of dimethyl ether in the gas fed to the reactor is preferably 10 mol% or more, more preferably 20 mol% or more from the viewpoint of productivity and economy. Further, the concentration of dimethyl ether in the gas fed to the reactor is preferably 40 mol% or less, more preferably 30 mol% or less, from the viewpoint of suppressing the calorific value and suppressing deterioration of the catalyst.

  The concentration of hydrogen in the gas fed to the reactor is preferably 2 moles or more, more preferably 2.5 moles or more with respect to 1 mole of dimethyl ether, from the viewpoint of hydrogenation rate and suppression of catalyst deterioration. Further, the concentration of hydrogen in the gas fed to the reactor is preferably 5 mol or less, more preferably 4 mol or less, with respect to 1 mol of dimethyl ether from the viewpoint of productivity and economy.

  The gas fed into the reactor may contain, for example, methanol, water, inert gas, etc., in addition to dimethyl ether and hydrogen which are reaction raw materials. Methanol is also a reaction raw material and reacts with hydrogen in the presence of a liquefied petroleum gas production catalyst to produce paraffins. The gas fed into the reactor may contain carbon monoxide and / or carbon dioxide.

  The dimethyl ether-containing gas and hydrogen (hydrogen-containing gas) may be mixed and supplied to the reactor, or may be separately supplied to the reactor.

  The reaction temperature is preferably 300 ° C. or higher, more preferably 320 ° C. or higher, from the viewpoint of obtaining higher catalytic activity. Further, the reaction temperature is preferably 470 ° C. or less, more preferably 450 ° C. or less, from the viewpoint of higher hydrocarbon selectivity, and further higher propane and butane selectivity and catalyst life. 400 ° C. or less is particularly preferable.

  The reaction pressure is preferably 0.1 MPa or more, more preferably 0.15 MPa or more, from the viewpoint of higher activity and the operability of the apparatus. In addition, the reaction pressure is preferably 3 MPa or less, more preferably 2.5 MPa or less, particularly preferably less than 2 MPa, and further preferably 1.5 MPa or less from the viewpoints of economy and safety. In addition, by making the reaction pressure 2.5 MPa or less, more preferably 1.5 MPa or less, carbon monoxide and carbon dioxide by-products can be more sufficiently suppressed.

  Furthermore, according to the present invention, LPG can be produced under a lower pressure. Specifically, LPG can be synthesized from dimethyl ether and hydrogen under a pressure of less than 1 MPa or even 0.6 MPa or less.

Gas space velocity, in terms of economic efficiency, preferably 1500 hr ^-1 or more, 1800Hr ^-1 or more is more preferable. Further, the gas space velocity is higher activity can be obtained and, from the point of higher selectivity for propane and butane is obtained, preferably 60000Hr ^-1 or less, 30000 hr ^-1 or less is more preferable.

  The gas fed into the reactor can be divided and fed into the reactor, thereby controlling the reaction temperature.

  The reaction can be carried out in a fixed bed, a fluidized bed, a moving bed, etc., but it is preferable to select from both aspects of control of reaction temperature and catalyst regeneration method. For example, as a fixed bed, a quench reactor such as an internal multi-stage quench system, a multi-tube reactor, a multi-stage reactor including a plurality of heat exchangers, a multi-stage cooling radial flow system or a double-tube heat exchange Other reactors such as a system, a built-in cooling coil system, and a mixed flow system can be used.

  The liquefied petroleum gas production catalyst can be diluted with silica, alumina, or an inert and stable heat conductor for the purpose of temperature control. In addition, the liquefied petroleum gas production catalyst can be applied to the surface of the heat exchanger for the purpose of temperature control.

  According to the second method for producing LPG of the present invention, the LPG synthesis reaction can be carried out at a conversion rate of dimethyl ether of 99% or more, more preferably about 100%. In addition, according to the second LPG production method of the present invention, LPG synthesis can be performed with high activity and high selectivity at a conversion rate from dimethyl ether to hydrocarbon of 90% or more, more preferably 95% or more, and even 98% or more. The reaction can be performed.

  In the reaction product gas (lower paraffin-containing gas) obtained in this way, the main component of the contained hydrocarbon is propane or butane. From the viewpoint of liquefaction characteristics, the higher the total content of propane and butane in the lower paraffin-containing gas, the better. In the second LPG production method of the present invention, the total content of propane and butane is 40% or more, further 45% or more, further 50% or more (including 100%) based on the carbon content of the hydrocarbons contained. ), Which is a lower paraffin-containing gas.

  Further, the obtained lower paraffin-containing gas preferably has more propane than butane from the viewpoint of combustibility and vapor pressure characteristics.

  In addition, the obtained lower paraffin-containing gas usually contains moisture, a low-boiling component that is a substance having a boiling point or sublimation point lower than that of propane, and a high-boiling component that is a substance having a boiling point higher than that of butane. It is. Examples of the low boiling point component include hydrogen as an unreacted raw material, ethane as a by-product, methane, carbon monoxide, and carbon dioxide. Examples of the high-boiling component include high-boiling paraffins (pentane, hexane, etc.) that are by-products.

  Therefore, moisture, a low boiling point component, a high boiling point component, etc. are isolate | separated from the obtained lower paraffin containing gas as needed, and liquefied petroleum gas (LPG) which has propane or butane as a main component is obtained. If necessary, dimethyl ether, which is an unreacted raw material, is also separated by a known method.

  Separation of moisture, low-boiling components, and high-boiling components can be performed by known methods.

  Separation of moisture can be performed, for example, by liquid-liquid separation.

  Separation of low-boiling components can be performed, for example, by gas-liquid separation, absorption separation, distillation or the like. More specifically, it can be carried out by gas-liquid separation or absorption separation at pressurized normal temperature, gas-liquid separation or absorption separation after cooling, or a combination thereof. Moreover, it can also carry out by membrane separation or adsorption separation, and can also carry out by the combination of these, gas-liquid separation, absorption separation, and distillation. For the separation of low-boiling components, a gas recovery process commonly used in refineries (“Petroleum Refining Process”, Petroleum Society / Ed., Kodansha Scientific, 1998, p.28-p.32) is applied. be able to.

  As a method for separating the low-boiling components, an absorption process in which liquefied petroleum gas mainly composed of propane or butane is absorbed in an absorbing liquid such as high-boiling paraffin gas having a boiling point higher than butane or gasoline is preferable.

  Separation of high-boiling components can be performed, for example, by gas-liquid separation, absorption separation, distillation, or the like.

  The separation conditions can be appropriately determined according to a known method.

  Moreover, in order to obtain liquefied petroleum gas, you may pressurize and / or cool as needed.

  For consumer use, from the viewpoint of safety at the time of use, for example, the content of low-boiling components in LPG is preferably 5 mol% or less (including 0 mol%) by separation.

  Further, the low boiling point component separated from the lower paraffin-containing gas in this liquefied petroleum gas production process can be recycled as a raw material for the synthesis gas production process.

  All the low-boiling components separated from the lower paraffin-containing gas may be recycled to the synthesis gas production process, or a part may be extracted out of the system and the rest may be recycled to the synthesis gas production process. As for the low boiling point component, only a desired component can be separated and recycled to the synthesis gas production process.

  In this case, in the synthesis gas production process, the content of low-boiling components in the gas fed to the reformer, which is a reactor, that is, the content of the recycled material can be determined as appropriate.

  In order to recycle the low boiling point component, a known technique such as appropriately providing a pressure raising means in the recycle line can be employed.

  The total content of propane and butane in the LPG produced in this manner can be 90% or more, further 95% or more (including 100%) based on the amount of carbon. In addition, the content of propane in the produced LPG can be 50% or more, further 60% or more, further 65% or more (including 100%) on the basis of carbon amount. According to the second LPG production method of the present invention, it is possible to produce LPG having a composition suitable for propane gas that is widely used as a fuel for household and business use.

  As described above, according to the present invention, a hydrocarbon whose main component is propane or butane, that is, liquefied petroleum gas (LPG), is economically supplied from a carbon-containing raw material such as natural gas via synthesis gas and dimethyl ether. Can be manufactured.

Claims (5)

(I) a synthesis gas production process for producing synthesis gas from a raw material gas containing a carbon-containing raw material and a carbon dioxide-containing gas recycled from the recycling process;
(Ii) Dimethyl ether for producing a dimethyl ether synthesis reaction product gas containing dimethyl ether and carbon dioxide from the synthesis gas obtained in the synthesis gas production process by reacting carbon monoxide with hydrogen in the presence of a catalyst for producing dimethyl ether. Manufacturing process,
(Iii) a separation step of separating a carbon dioxide-containing gas containing carbon dioxide and a dimethyl ether-containing gas containing dimethyl ether as a main component from the dimethyl ether synthesis reaction product gas obtained in the dimethyl ether production step;
(Iv) An olefin production process for producing an olefin-containing gas containing olefins whose main component is propylene or butene from the dimethyl ether-containing gas obtained in the separation process by reacting dimethyl ether in the presence of an olefin production catalyst. When,
(V) Liquefaction containing hydrocarbons whose main component is propane or butane from olefin-containing gas and hydrogen obtained in the olefin production process by reacting olefin and hydrogen in the presence of an olefin hydrogenation catalyst. An olefin hydrogenation process for producing petroleum gas;
(Vi) A method for producing liquefied petroleum gas, comprising a recycling step of recycling a part or all of the carbon dioxide-containing gas separated in the separation step to a synthesis gas production step. (I) a synthesis gas production process for producing synthesis gas from a raw material gas containing a carbon-containing raw material and a carbon dioxide-containing gas recycled from the recycling process;
(Ii) Dimethyl ether for producing a dimethyl ether synthesis reaction product gas containing dimethyl ether and carbon dioxide from the synthesis gas obtained in the synthesis gas production process by reacting carbon monoxide with hydrogen in the presence of a catalyst for producing dimethyl ether. Manufacturing process,
(Iii) a separation step of separating a carbon dioxide-containing gas containing carbon dioxide and a dimethyl ether-containing gas containing dimethyl ether as a main component from the dimethyl ether synthesis reaction product gas obtained in the dimethyl ether production step;
(Iv) Olefin-containing gas containing hydrogen and olefins whose main components are propylene or butene from dimethyl ether-containing gas and hydrogen obtained in the separation step by reacting dimethyl ether in the presence of a catalyst for olefin production An olefin production process for producing
(V) A liquefied petroleum gas containing a hydrocarbon whose main component is propane or butane from the olefin-containing gas obtained in the olefin production process by reacting olefin and hydrogen in the presence of an olefin hydrogenation catalyst. An olefin hydrogenation process to be produced;
(Vi) A method for producing liquefied petroleum gas, comprising a recycling step of recycling a part or all of the carbon dioxide-containing gas separated in the separation step to a synthesis gas production step. (I) a synthesis gas production process for producing synthesis gas from a raw material gas containing a carbon-containing raw material and a carbon dioxide-containing gas recycled from the recycling process;
(Ii) Dimethyl ether for producing a dimethyl ether synthesis reaction product gas containing dimethyl ether and carbon dioxide from the synthesis gas obtained in the synthesis gas production process by reacting carbon monoxide with hydrogen in the presence of a catalyst for producing dimethyl ether. Manufacturing process,
(Iii) a separation step of separating a carbon dioxide-containing gas containing carbon dioxide and a dimethyl ether-containing gas containing dimethyl ether as a main component from the dimethyl ether synthesis reaction product gas obtained in the dimethyl ether production step;
(Iv) Liquefaction containing hydrocarbons whose main component is propane or butane from dimethyl ether-containing gas and hydrogen obtained in the separation step by reacting dimethyl ether and hydrogen in the presence of a catalyst for liquefied petroleum gas production. A liquefied petroleum gas production process for producing petroleum gas;
(V) A method for producing a liquefied petroleum gas, comprising a recycling step of recycling a part or all of the carbon dioxide-containing gas separated in the separation step to a synthesis gas production step. In the synthesis gas production process, the raw material gas further, the production of liquefied petroleum gas according to claim 1 comprising at least one selected from the group consisting of H 2 _O, O ₂ and CO ₂ Method.   The liquefaction according to any one of claims 1 to 4, wherein the content of hydrogen in the synthesis gas obtained in the synthesis gas production step is 0.5 to 1.5 mol with respect to 1 mol of carbon monoxide. Oil gas production method.

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