CN102659500B - Method for producing ethylene and ethane and catalytic reactor - Google Patents

Abstract

A method for producing ethylene and ethane and a catalytic reactor, belonging to the technical field of low-carbon hydrocarbons. After the methane-rich raw material gas and oxidizing gas pass through the first stage of granular catalyst for the first methane catalytic conversion reaction, the reaction mixture is supplemented with oxidizing gas and then enters the second stage of monolithic catalyst reaction section for the second reaction. Catalytic conversion reaction of methane, and the final collection of reaction products; the top of the catalytic reactor is a pre-mixing chamber with a feed gas inlet and an oxidizing gas inlet, and the lower end is connected to the first-stage reactor with a granular catalyst, which is connected to it The first one is the oxidizing gas replenisher, which is connected with the second-stage reactor equipped with monolithic catalyst, and the product outlet is opened at the lower end. The invention improves the single-pass methane conversion rate of methane catalytic conversion reaction, has short process flow, stable operation and low equipment investment.

Description

A method and catalytic reactor for producing ethylene and ethane

technical field

The invention relates to a method for preparing ethylene and ethane and a catalytic reactor for realizing the method, belonging to the technical field of low-carbon hydrocarbons.

Background technique

Methane-rich coalbed methane, natural gas, and biogas are important resources. In addition to being directly used as fuel, they can be converted into basic chemical raw materials such as ethylene and ethane through catalytic conversion, which can greatly increase their added value and reduce oil consumption. Catalytic conversion methods can be divided into indirect method and direct method.

The indirect method is to firstly convert the methane-rich feed gas into synthesis gas (mainly CO and H ₂ ), then make the synthesis gas into raw materials such as methanol, dimethyl ether, and low-carbon hydrocarbons, and finally through catalytic conversion Preparation of low-carbon olefins such as ethylene. Its main problems are too long technological process, high energy consumption and low production efficiency.

The direct method is to catalytically react the methane-rich raw material gas with oxygen or air and other oxidizing gases under the action of a catalyst, and convert it into low-carbon hydrocarbons such as ethylene and ethane in one step. The method has simple technological process and convenient operation, and has important industrialization prospects.

Contents of the invention

The object of the present invention is to provide a method for directly catalytically converting raw material gas rich in methane into ethylene and ethane and a catalytic reactor for realizing the above method.

In order to achieve the above object, the method for directly catalytically converting methane-rich raw material gas into ethylene and ethane provided by the present invention is to use methane-rich raw material gas to react with oxidizing gas under the action of a catalyst to directly catalyze The conversion into ethylene and ethane is characterized in that it includes two stages and two types of catalyst catalytic processes. The first stage is a granular catalyst, and the second stage is a monolithic catalyst. The catalytic process of two types of catalysts specifically includes the following steps: After the methane raw material gas and oxidizing gas pass through the first stage of granular catalyst for the first methane catalytic conversion reaction, the reaction mixture is supplemented with oxidizing gas and then enters the second integral catalyst reaction section for the second methane catalytic conversion reaction, and finally collect the reaction product.

The raw material gas rich in methane is one or more of coalbed methane, natural gas and biogas; the oxidizing gas is oxygen or air.

The catalytic reaction of the present invention is preferably carried out under the pressure condition of 0.1-1.5 MPa, the raw material gas and the oxidizing gas pass through the catalyst at a gas space velocity of 1.0 x 10 ² -5.0 x 10 ⁶ h ^-1 , the first stage and the second stage The reaction temperature of the stage catalyst stage is between 700°C and 900°C.

In the above method, in raw material gases such as methane-rich coalbed methane, natural gas, and biogas, the more ideal methane volume content is more than 90%; the oxidizing gas is more ideally oxygen; The molar ratio of methane in the raw material gas to oxygen in the oxidizing gas is 2 to 4:1, ideally 3:1; The supplementary oxidizing gas is oxygen or air, more ideally oxygen, and the quantity of supplementary oxidizing gas is (2～4) according to the molar ratio of the methane in the raw material gas of the first stage and supplementary oxygen: (0.01 ～0.30), the more ideal is 3:0.15. The granular catalyst material in the first stage is a conventional existing catalyst for oxidative coupling of methane to ethylene and ethane, and its structure is granular, with a particle size of 2-10 mm; The existing catalysts for oxidative coupling of methane to ethylene and ethane are monolithic catalysts with a pore structure.

The catalyst for direct catalytic conversion of raw material gas rich in methane into ethylene and ethane of the present invention is a two-stage bed catalyst composed of a granular catalyst in the first stage and a monolithic catalyst in the second stage in a certain way. composition. According to the characteristics of strong exothermicity and easy further oxidation of the products ethylene and ethane in the direct catalytic conversion reaction of methane, the present invention proposes a two-stage catalyst with simple structure, low investment, low energy consumption, convenient operation and stability. reactor. The first section of the reactor is filled with granular catalysts for the first catalytic conversion of methane. Immediately after the first methane catalytic conversion reaction, there is a mixing chamber in which the reaction mixture gas supplements the oxidizing gas. Then there is the second section of the reactor, which is filled with a monolithic catalyst for the second catalytic conversion of methane. The bottom of the reactor is the product outlet.

The catalytic reactor for realizing the above method provided by the present invention is characterized in that the catalytic reactor includes a pre-mixer 3, a first-stage reactor 4 filled with a first-stage catalyst, an oxidizing gas replenisher 6 and a filling The second-stage reactor 7 of the second-stage catalyst is installed, and the top of the catalytic reactor is a pre-mixing chamber 3, and the pre-mixing chamber 3 is provided with a feed gas inlet 1 and an oxidizing gas inlet 2, and the pre-mixing chamber 3 The lower end is connected to the first-stage reactor 4, and the granular catalyst 5 is placed in the first-stage reactor 4; the oxidizing gas replenisher 6 is connected to the lower end of the first-stage reactor 4, and the oxidizing gas replenisher 6 is connected to the first-stage reactor 4 and is composed of a shell of equal diameter and uniformly distributed circular tubes connected to the first-stage reactor 4 and the second-stage reactor 7 in the shell. There is an air inlet, the diameter of the circular tube is 0.5-1mm, and there are symmetrically distributed holes with a diameter of 0.1-0.3mm in the middle of the circular tube; the second section is connected to the other end of the oxidizing gas replenisher 6 Reactor 7, a monolithic catalyst is housed in the second-stage reactor 7, and a product outlet 8 is opened at the lower end of the second-stage reactor 7.

The reactors, preferably the first-stage reactor 4 and the second-stage reactor 7 have an aspect ratio of 1-3.

In the reactor, preferably, the aspect ratio of the oxidizing gas supplement is 0.1-0.2.

The reaction temperature can be provided by the heating device of the shell of the catalytic reactor (known technology device).

The present invention has following remarkable advantage:

(1) Due to the excellent heat and mass transfer performance of the monolithic catalyst, the catalytic reactor adopts a two-stage structure in which the first stage is filled with a granular methane catalytic conversion catalyst, and the second stage is filled with a monolithic methane catalytic conversion catalyst, which can The large amount of heat of reaction generated after the catalytic conversion of methane by the first-stage granular catalyst, as well as the products ethylene and ethane produced by the reaction, quickly pass through the second-stage monolithic catalyst and are exported to the reaction section of the catalytic reactor. While increasing the conversion rate of methane, it can avoid deep oxidation of ethylene and ethane and improve the selectivity of ethylene and ethane, which cannot be achieved by a one-stage catalytic reactor.

(2) Between the granular catalyst for the first catalytic conversion of methane in the first stage of the reactor and the monolithic catalyst for the second catalytic conversion of methane in the second stage, the mixing chamber for supplementing oxidizing gas is set up for the first methane After the catalytic conversion, the unconverted methane in the mixed gas provides the oxidizing gas for catalytic conversion again, thereby increasing the single-pass methane conversion rate of the methane catalytic conversion reaction, and further greatly increasing the single-pass yield of ethylene and ethane.

(3) The two-stage catalytic conversion of methane to ethylene and ethane catalytic reactor has simple structure, short overall process flow, stable operation, low equipment investment, and high integration of resources, energy, equipment and processes, and then Strengthen the catalytic reaction process.

The direct catalytic conversion of methane-rich feed gas to ethylene and ethane has the following characteristics: (1) The content range of methane in the feed gas is relatively wide, and usually the content of methane above 50% has development value; (2) Oxidation The gas is relatively wide, and oxygen, air, etc. can be used; (3) The by-products of the reaction are less, only a small amount of CO, CO ₂ , H ₂ O, etc., and the refining and purification of ethylene and ethane are relatively easy. Using the monolithic catalyst, the unconverted methane after the reaction of the granular catalyst in the first stage can be used for the catalytic conversion reaction again with the oxidizing gas provided by the supplementary oxidizing gas mixing chamber. At the same time, due to the excellent heat and mass transfer performance of the monolithic catalyst, a large amount of reaction heat generated by the catalytic conversion of methane and low-carbon hydrocarbons such as ethylene and ethane produced by the reaction can be quickly exported to the reaction section of the catalytic reactor, thereby While improving the conversion rate of methane, the deep oxidation of ethylene and ethane is avoided, and the single-pass yield of ethylene and ethane is greatly improved.

Description of drawings

Fig. 1 is a structural schematic diagram of the catalytic reactor of the present invention.

Fig. 2 is in the catalytic reactor of the present invention, between the first stage catalyzer and the second stage catalyzer, the partial schematic diagram of the mixing chamber of replenishing oxidizing gas;

In the above drawings, 1 raw material gas inlet, 2 oxidizing gas inlet, 3 premixing chamber, 4 first stage reactor, 5 granular catalyst, 6 oxidizing gas replenisher, 7 second stage reactor, 8 product outlet.

Detailed ways

The following is a detailed description of the present invention, which does not constitute any limitation to the present invention. The known technical parts involved in the present invention are not described in detail, nor are they marked in the accompanying drawings. In addition, the feed gas of the present invention may be one or more of methane-rich coalbed methane, natural gas, and biogas. For the convenience of describing the present invention, coalbed methane is used as the feedstock gas for illustration. According to the description of this embodiment, those skilled in the art can understand that the present invention can also be accomplished by using other raw material gases.

The catalytic reaction of the present invention is carried out under the pressure condition of 0.1-1.5MPa, and the raw material gas and the oxidizing gas enter the gas pre-mixing at the top of the catalytic reactor at a gas space velocity of 1.0 x 10 ² -5.0 x 10 ⁶ h ^-1 The chamber is mixed evenly, and then enters the first stage of the catalytic reactor to react, and the reaction temperature is between 700°C and 900°C. The reacted gas is uniformly mixed with the supplementary oxidizing gas in the mixing chamber of supplementary oxidizing gas between the first-stage catalyst and the second-stage catalyst, and then enters the second-stage catalyst of the catalytic reactor for catalytic conversion reaction, The reaction temperature is between 700°C and 900°C, and finally the product is led out of the catalytic reactor.

Catalytic reactor of the present invention is shown in Fig. 1 and is the cylindrical space that is made of metal shell, and the top of this catalytic reactor is equipped with raw material gas and oxidizing gas premixing chamber 3, communicates raw material gas inlet 1 and oxidizing gas by premixing chamber 3 The oxidizing gas inlet 2 makes the raw material gas entering the catalytic reactor and the oxidizing gas mix evenly, and then enters the first stage of the catalytic reactor with a granular catalyst for reaction. The first-stage particle catalyst 5 is a catalyst (known technology) for oxidative coupling of methane to ethylene and ethane with a particle size of 2 to 10 mm, such as 3(wt)%Ce/5(wt)%Na ₂ WO with a particle size of 3mm ₄ -2(wt)%Mn/SBA-15 granular catalyst.

In the catalytic reactor of the present invention, between the first-stage catalyst and the second-stage catalyst, there is a mixing chamber 6 for supplementing oxidizing gas (see Figure 2 for a partial schematic diagram of the mixing chamber), which is a column with the same diameter as the catalytic reactor. The cylindrical space consists of a circular tube with a diameter of 0.5-1mm. The upper and lower ends of the circular tube are respectively connected with the first-stage reactor and the second-stage reactor. mm holes, through these holes, the oxidizing gas is added to the gas after the reaction of the first-stage catalyst, and then enters the second-stage monolithic catalyst 7.

The second stage monolithic catalyst 7 of the catalytic reactor of the present invention is a monolithic methane oxidative coupling ethylene, ethane catalyst, such as adopting the cordierite honeycomb ceramics with a pore diameter of 1 mm as 3 (wt)% of the monolithic carrier Ce/5(wt)%Na ₃ PO ₄ -2(wt)%Mn/SBA-15/cordierite monolithic catalyst. This monolithic catalyst with a pore structure can convert the unconverted methane after the reaction of the granular catalyst in the first stage, and the oxidizing gas provided by the supplementary oxidizing gas mixing chamber 6 to carry out catalytic conversion reaction again. At the same time, due to the excellent heat and mass transfer performance of the monolithic catalyst 7, a large amount of heat of reaction generated by the catalytic conversion of methane, as well as the products ethylene and ethane generated by the reaction, can be quickly exported to the reaction section of the catalytic reactor, thereby increasing the While the methane conversion rate is high, the deep oxidation of ethylene and ethane is avoided, and the single-pass yield of ethylene and ethane is greatly improved. The reaction product enters the heat recovery device (known technology) through the product outlet 8 located at the bottom of the catalytic reactor. The reaction product mixed gas passing through the heat recovery device can enter the product separation system after exchanging heat with the raw material gas and oxidizing gas through a heat exchanger (known technology).

The catalyst in the first stage of the catalytic reactor used in the following table is 3(wt)%Ce/5(wt)%Na ₂ WO ₄ -2(wt)%Mn/SBA-15 granular catalyst with a particle size of 3mm, No. The second stage catalyst is 3(wt)%Ce/5(wt)%Na ₃ PO ₄ -2(wt)%Mn/SBA-15/cordierite monolithic catalyst. The length of the first catalyst bed is 50mm and the diameter is 25mm. The second catalyst bed has a length of 50 mm and a diameter of 25 mm. The CH ₄ content of raw coalbed methane is 100%, and the oxidizing gas substance is O ₂ . The reaction pressure is 0.1 MPa, the total gas space velocity of CH ₄ and O ₂ is 3.6 x 10 ⁴ h ^-1 , and the reaction temperature is 800°C. The molar ratio of methane in the raw material gas passing through the first stage granular catalyst to oxygen in the oxidizing gas is 3:1. The molar ratio of methane in the raw material gas of the first stage to supplementary oxygen is 3:0.15.

The reaction temperature is provided by a heating device in the shell of the catalytic reactor (known technology device).

Table 1 is the main component volume content (%) of coalbed methane and products used in this example

As can be seen from the above description, the innovation of the present invention is:

(1) The catalytic reactor adopts a two-stage structure in which the first stage is filled with a granular methane catalytic conversion catalyst, and the second stage is filled with a monolithic methane catalytic conversion catalyst. The monolithic catalyst has excellent heat and mass transfer performance, and is very A large amount of reaction heat generated after the catalytic conversion of methane by the first-stage granular catalyst, and low-carbon hydrocarbons such as ethylene and ethane produced by the reaction quickly pass through the second-stage monolithic catalyst and are exported to the reaction section of the catalytic reactor, thereby avoiding Deep oxidation of ethylene and ethane, which cannot be achieved by a one-stage catalytic reactor.

(2) Between the granular catalyst for the first methane catalytic conversion in the first stage of the catalytic reactor and the monolithic catalyst for the second methane catalytic conversion in the second stage, the mixing chamber for supplementing oxidizing gas is set for the first time After the catalytic conversion of methane, the unconverted methane in the mixed gas provides the oxidizing gas for catalytic conversion again, which greatly increases the single-pass total yield of ethylene and ethane while increasing the conversion rate of methane.

(3) The two-stage catalytic conversion of methane to ethylene and ethane catalytic reactor has simple structure, short overall process flow, stable operation, low equipment investment, and high integration of resources, energy, equipment and processes, and then Strengthen the catalytic reaction process.

Claims (1)

1. A kind of method that the raw material gas that is rich in methane is directly catalytically converted into ethylene, ethane, it is characterized in that, this catalytic reactor comprises premixer, the first-stage reactor of packing first-stage catalyst, oxidizing The gas replenisher and the second-stage reactor filled with the second-stage catalyst, the top of the catalytic reactor is a pre-mixing chamber, the pre-mixing chamber is provided with a feed gas inlet and an oxidizing gas inlet, and the lower end of the pre-mixing chamber The first-stage reactor is connected to each other, and there is a granular catalyst in the first-stage reactor; the oxidizing gas replenisher is connected to the lower end of the first-stage reactor, and the oxidizing gas replenisher is formed by reacting with the first stage. The housing is connected with the reactor and has equal diameters, and the circular tubes in the shell are connected with the first-stage reactor and the second-stage reactor and are evenly distributed. The shell is provided with an air inlet, and the diameter of the circular tube is 0.5-1mm, there are symmetrically distributed holes with a diameter of 0.1-0.3mm in the middle of the circular tube; the second-stage reactor is connected to the other end of the oxidizing gas replenisher, and the second-stage reactor is equipped with a whole Formula catalyst, the lower end of the second stage reactor has a product outlet; During the reaction, the methane-rich raw material gas and oxidizing gas pass through the first stage of granular catalyst for the first methane catalytic conversion reaction, and the reaction mixture is supplemented with oxidizing gas and then enters the second stage of the monolithic catalyst reaction stage for the second stage. Catalytic conversion reaction of methane, and finally collect the reaction product; The catalyst in the first stage of the catalytic reactor is 3(wt)%Ce/5(wt)%Na ₂ WO ₄ -2(wt)%Mn/SBA-15 granular catalyst with a particle size of 3mm, and the catalyst in the second stage is 3 (wt)%Ce/5(wt)%Na ₃ PO ₄ -2(wt)%Mn/SBA-15/cordierite monolithic catalyst; the length of the first stage catalyst bed is 50mm, and the diameter is 25mm; the second stage The length of the catalyst bed is 50mm, and the diameter is 25mm; the CH ₄ content of the raw coalbed methane is 100%, and the oxidizing gas substance is O ₂ ; the reaction pressure is 0.1MPa, and the total gas space velocity of CH ₄ and O ₂ is 3.6x10 ⁴ h ^-1 , the reaction temperature is 800°C; the reaction gas composition: the molar composition of methane in the raw material gas and oxygen in the oxidizing gas passing through the first stage granular catalyst is 72.3% of methane, 24.1% of oxygen, and the mole of supplementary oxygen Percentage 3.6%.