阅读说明：本技术 一种甲烷氧化偶联制烯烃的混氧工艺 (Oxygen mixing process for preparing olefin by oxidative coupling of methane ) 是由 李少鹏 刘罡 孙丽丽 盛在行 王振维 聂毅强 丁利伟 赵百仁 于 2019-03-27 设计创作，主要内容包括：本发明属于石油化工领域,具体涉及一种甲烷氧化偶联制烯烃的混氧工艺,包括：富甲烷气体与第一富氧气体混合形成原料气,所述原料气的温度低于甲烷自燃点,原料气中氧气的含量低于30体积％,该原料气经升温后进入反应器,在催化剂作用下发生氧化偶联反应,得到至少包含CO、CO<Sub>2</Sub>、乙烯、乙烷、碳三及以上组分的反应产品气,其中,在形成原料气之后的阶段,将第二富氧气体分一次或多次注入所述反应器。本发明的有益效果在于：体系中整体的氧浓度始终处于一个较低的状态,有利于异常工况时脱离危险状态。(The invention belongs to the field of petrochemical industry, and particularly relates to an oxygen mixing process for preparing olefin by oxidative coupling of methane, which comprises the following steps: mixing the methane-rich gas and the first oxygen-rich gas to form a feed gas, wherein the temperature of the feed gas is lower than the spontaneous combustion point of methane, the content of oxygen in the feed gas is lower than 30% by volume, the feed gas is heated and then enters a reactor, and an oxidative coupling reaction is carried out under the action of a catalyst to obtain a product at least containing CO and CO 2 Ethylene, ethane, carbon, and combinations thereof, wherein a second oxygen-rich gas is injected into the reactor one or more times at a stage subsequent to the formation of the feed gas. The invention has the beneficial effects that: the whole oxygen concentration in the system is always in a lower state, which is beneficial to being separated from a dangerous state under abnormal working conditions.)

1. An oxygen mixing process for preparing olefin by oxidative coupling of methane is characterized in that methane-rich gas and first oxygen-rich gas are mixed to form a feed gas, the temperature of the feed gas is lower than the spontaneous combustion point of methane, the content of oxygen in the feed gas is lower than 30% by volume, the feed gas enters a reactor after being heated, and the feed gas is subjected to oxidative coupling reaction under the action of a catalyst to obtain a product at least containing CO and CO₂Ethylene, ethane, carbon, and combinations thereof, wherein a second oxygen-rich gas is injected into the reactor one or more times at a stage subsequent to the formation of the feed gas.

2. The oxygen mixing process for preparing olefin by oxidative coupling of methane as claimed in claim 1, wherein the oxygen content of the first oxygen-enriched gas and the oxygen content of the second oxygen-enriched gas are both 12% to 100% by volume.

3. The oxygen mixing process for preparing olefin by oxidative coupling of methane as claimed in claim 1, wherein the reactor is provided with a plurality of stages of catalyst beds connected in series.

4. The oxygen mixing process for preparing olefin by oxidative coupling of methane according to claim 3, wherein the number of stages of the catalyst bed is 2-6 stages.

5. The oxygen mixing process for preparing olefin by oxidative coupling of methane as claimed in claim 1, wherein the volume ratio of methane to oxygen at the inlet of each catalyst bed is 0.1: 1-80: 1.

6. the process of any one of claims 1 to 5, wherein the injection point of the second oxygen-enriched gas is close to the catalyst bed.

7. The oxygen-mixing process for the oxidative coupling of methane to olefins according to claim 6, wherein the residence time of the second oxygen-rich gas from the injection to the catalyst bed is not more than 100ms, preferably not more than 50 ms.

8. The oxygen-mixing process for the oxidative coupling of methane to olefins according to claim 1, wherein the methane-rich gas has a methane content of > 50% by volume, preferably > 70% by volume, and further preferably the methane-rich gas is natural gas and/or shale gas.

9. The oxygen mixing process for preparing olefin by oxidative coupling of methane as claimed in claim 1, wherein the oxygen content of the reaction product gas at the outlet of the reactor is lower than the maximum allowable oxygen concentration.

10. The oxygen mixing process for preparing olefin by oxidative coupling of methane according to claim 1, wherein the temperature of the oxidative coupling reaction is 600-1100 ℃, and the pressure is 0.01-1.5 MPaG, preferably 0.05-0.7 MPaG.

Technical Field

The invention belongs to the field of petrochemical industry, and particularly relates to an oxygen mixing process for preparing olefin by oxidative coupling of methane.

Background

Ethylene is one of the chemical products with the largest yield in the world, the ethylene industry is the core of the petrochemical industry, and the ethylene product accounts for more than 75 percent of petrochemical products and occupies an important position in national economy. Ethylene production has been used worldwide as one of the important indicators for the development of petrochemical in one country.

With the large fluctuation of the international crude oil price and the technical progress, in order to change the condition that the raw materials for producing ethylene depend on petroleum resources excessively, the raw materials for producing ethylene are changed, and the technology for producing ethylene by taking methanol as the raw material is developed and becomes a technology with wide industrial application in the novel coal chemical industry technology.

The technology for preparing ethylene by oxidative coupling of methane is an important technology for producing ethylene, takes natural gas as a raw material, can prepare ethylene by only one-step reaction process, and has high theoretical value and economic value. After more than 30 years of research, the research on ethylene preparation by a methane one-step method has made a breakthrough, and the industrial demonstration device for preparing ethylene by methane coupling is successfully put into production, which is moving towards the beginning of industrialization. The method has great significance for breaking the bottleneck of raw material sources in the ethylene industry, reducing the production cost and enhancing the competitiveness of the ethylene industry and downstream industries.

Research and development at home and abroad are most typical of Siluria technology company in the United states, and Siluria develops an industrially feasible methane direct-made ethylene catalyst by precisely synthesizing a nanowire catalyst by using a biological template. The catalyst can efficiently catalyze the conversion of methane into ethylene under the condition of 200-300 ℃ lower than the operation temperature of the traditional steam cracking method and under the pressure of 5-10 atmospheric pressures. The technology is used for prolonging the service life of the catalyst, greatly reduces the operation temperature, but has no substantial breakthrough on the conversion rate of methane and the yield of ethylene.

Disclosure of Invention

The invention aims to provide an oxygen mixing process for preparing olefin by oxidative coupling of methane, so that the major fire and explosion risks caused by excessive oxygen added at one time are avoided, oxygen is added in sections along with oxygen consumption of a system, and the system can rapidly enter a safety zone under abnormal working conditions.

The explosion triangle of the OCM reaction in one embodiment of the present invention is shown in fig. 1, and based on the analysis of the explosion triangle, the inventors of the present invention propose a segmented oxygen-mixed OCM process: the methane and the oxygen are mixed for the first time at a low temperature to obtain the low-temperature low-oxygen-content oxygen-poor feed gas, because the temperature is lower than the methane spontaneous combustion point, combustion and explosion cannot be generated, and then the oxygen-poor feed gas and the oxygen-rich feed gas are mixed for the second time at a high temperature to pass through an explosion area, so that the explosion danger is avoided.

Specifically, the invention provides a process for preparing olefin by oxidative coupling of methane, wherein methane-rich gas and first oxygen-rich gas are mixed to form a feed gas, the temperature of the feed gas is lower than the methane spontaneous combustion point, the content of oxygen in the feed gas is lower than 30% by volume, the feed gas enters a reactor after being heated, and the feed gas is subjected to oxidative coupling reaction under the action of a catalyst to obtain a product at least containing CO and CO₂Ethylene, ethane, carbon, and combinations thereof, wherein a second oxygen-rich gas is injected into the reactor one or more times at a stage subsequent to the formation of the feed gas.

According to the present invention, preferably, the oxygen content of each of the first oxygen-enriched gas and the second oxygen-enriched gas is 12% to 100% by volume. The oxygen content is controlled to reduce the time or likelihood that each segment enters the explosive limit. The first oxygen-enriched gas and the second oxygen-enriched gas may each contain a non-oxygen component comprising at least one of nitrogen, argon, carbon dioxide, methane, ethane, and water vapor.

According to the invention, preferably, a plurality of stages of catalyst beds connected in series are arranged in the reactor. The specific preferable number of the sections is 2-6 sections.

According to the invention, the volume ratio of methane to oxygen at the inlet of each section of catalyst bed is preferably 0.1: 1-80: 1. the above-mentioned alkoxy ratio can be adjusted by the addition of the second oxygen-rich gas.

According to the invention, preferably, the injection point of the second oxygen-enriched gas is close to the catalyst bed. The inventor finds that the specific arrangement position of the injection point has a large influence on the reaction, and compared with the mode of arranging the injection point at the inlet of the reactor, the injection point close to the catalyst bed layer can better realize the control of the process condition, thereby improving the methane conversion rate and the ethylene selectivity. The expression "close to the catalyst bed" includes both a position close to the catalyst bed outside the catalyst bed and a position close to the catalyst bed inside the catalyst bed. Specifically, the residence time of the second oxygen-rich gas from the injection to the bed is preferably not more than 100ms, and further preferably not more than 50 ms. By controlling the residence time, the raw material loss caused by methane combustion can be reduced, the reaction process is accelerated, the thermal explosion risk is obviously reduced, and the process safety is improved.

According to the present invention, preferably the methane-rich gas has a methane content of > 50% by volume, preferably > 70% by volume, further preferably the methane-rich gas is preferably natural gas and/or shale gas.

In the present invention, it is preferable to control the oxygen content of the reaction product gas at the outlet of the reactor to be lower than the maximum allowable oxygen concentration. The "maximum allowable oxygen concentration" varies depending on the reaction conditions, and the calculation method thereof is well known to those skilled in the art. Typically, the maximum allowable oxygen concentration in an OCM process is 3% to 50%.

According to the invention, the temperature of the oxidative coupling reaction is preferably 600-1100 ℃, and the pressure is 0.01-1.5 MPaG, preferably 0.05-0.7 MPaG.

The invention has the beneficial effects that: the whole oxygen concentration in the system is always in a lower state, which is beneficial to being separated from a dangerous state under abnormal working conditions.

Additional features and advantages of the invention will be set forth in the detailed description which follows.

Drawings

The above and other objects, features and advantages of the present invention will become more apparent by describing in more detail exemplary embodiments thereof with reference to the attached drawings.

FIG. 1 shows an exploded triangle of OCM reaction in one embodiment of the present invention.

FIG. 2 shows a process diagram for preparing olefin by oxidative coupling of methane in one embodiment of the present invention.

Description of the reference numerals

S1, raw material gas; s2, reacting product gas; s3, and oxygen.

1. A catalyst bed layer; 2. taking heat measures; 3. an oxygen injection point.

Detailed Description

Preferred embodiments of the present invention will be described in more detail below. While the following describes preferred embodiments of the present invention, it should be understood that the present invention may be embodied in various forms and should not be limited by the embodiments set forth herein.