A system and method for directly producing aromatics from methane

Abstract

The invention discloses a system and a method for directly preparing aromatic hydrocarbon from methane. The system comprises a methane aromatization sub system, a methanation reaction sub system and a separating sub system. The method comprises the following steps: cooling a high-temperature gas mixture of hydrogen gas, methane and aromatic hydrocarbon from the outlet of the methane aromatization sub system; directly reacting the cooled gas mixture with CO2 in the methanation reaction sub system to obtain a mixture of methane, CO2, water and aromatic hydrocarbon; and performing gas-liquid separation on the mixture to obtain aromatic hydrocarbon, wherein the methane can be recycled. According to the system and the method, the problems of high energy consumption of the separation of the gas and the aromatic hydrocarbon in an independent aromatization process and high cost are effectively solved, heat energy contained in the gas from the outlet of the aromatization system is effectively utilized, and the advantages of low methane consumption, short process, less investment, and the capacity of greatly utilizing CO2 and greatly reducing the cost of the aromatic hydrocarbon are achieved.

Description

technical field [0001] The invention belongs to the technical field of chemical industry, in particular to a system and method for directly preparing aromatics from methane. Background technique [0002] Aromatic products are important basic chemical raw materials and are currently mainly obtained through petroleum routes. However, due to the raw material competition in the production of olefins and oil products (gasoline and diesel oil, etc.), the production of aromatics from petroleum routes is increasingly restricted. my country needs to import a large amount of aromatics every year. [0003] Using methane as a raw material and converting it with a metal-molecular sieve dual-functional catalyst in an oxygen-free environment, important aromatics such as benzene, toluene, and naphthalene can be obtained. However, due to thermodynamic equilibrium limitations, the single-pass conversion rate of the aromatization reaction carried out at 600-700° C. is low (about 16%), and th...

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Problems solved by technology

[0004] In order to overcome the above-mentioned shortcoming of the prior art, the object of the present invention is to provide a kind of system and the method for directly preparing aromatics with methane, after the tail gas of methane aromatization reaction system exit is through heat exchange, directly with CO 2 React in a suitable temperature range, and then use separation technology to separate aromatics, water and gas (methane, containing a small amount of residual hydrogen). Methane gas can be cycled and converted, which not only avoids the problem of high energy consumption for the separation of aromatics and methane hydrogen, but also simplifies the process. At the same time, the process heat energy is effectively used, which has the advantages of reducing equipment investment and aromatics production cost

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