Absorbent for collecting and separating CO2 and use thereof

Abstract

The invention provides an absorbent for collecting and separating CO2, which contains 5 to 95 weight percent of dimethyl carbonate and 95 to 5 weight percent of organic solvent, wherein the organic solvent is one or more of hydrocarbon, ether or ester solvents. The invention has the advantages that: the absorbent is prepared by mixing the dimethyl carbonate and the organic solvent, so the freezing point of the dimethyl carbonate can be lowered, the CO2 absorption effect of the dimethyl carbonate is not changed, but even is increased; the problem that sharp viscosity increase or freezing during the use of the dimethyl carbonate at a lower temperature influence the use effect of the dimethyl carbonate is solved; and thus, the process is simplified effectively and cost is reduced.

Description

technical field [0001] The present invention relates to a CO 2 Absorbents, in particular, methods for capturing and separating CO from gas mixtures 2 Absorbents and their applications. Background technique [0002] Global warming has become an undisputed fact. Greenhouse gas CO 2 emissions are a major contributor to climate warming. How to get from rich CO 2 Capture and separation of CO in the gas mixture of synthetic gas, shift gas and IGCC gas 2 extremely important. [0003] According to different application occasions and the pressure of feed gas, the decarburization method can be divided into dry method and wet method. Dry methods include adsorption methods and membrane methods, and are generally applicable to CO 2 Where the concentration is low; the wet method can be divided into chemical absorption method and physical absorption method, and the chemical absorption method is mostly used in occasions where the raw material gas pressure is low. [0004] The raw m...

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Problems solved by technology

[0006] The low-temperature methanol washing method has the characteristics of large absorption capacity, good selectivity, high gas purification degree, and good absorbent stability, but it has long process flow, large equipment investment (requires low-temperature resistant materials below -30°C), and absorbent toxicity. Yamato needs to pay high foreign patent technology fees and other shortcomings; the propylene carbonate method can effectively absorb CO due to the high partial pressure of propylene carbonate 2 , and it can be easily desorbed without heat at a lower pressure, and its process flow, especially the desorption process, can be considerably simplified, but due to the limited absorption capacity, the circulation of the absorbent is large and the energy consumption is large The polyethylene glycol dimethyl ether method has the characteristics of strong absorption capacity and low absorbent loss (low vapor pressure), but polyethylene glycol dimethyl ether must be artificially synthesized, and the cost of the absorbent is high, and the molecular weight of the absorbent is relatively large , easy to polymerize and cause loss during the regeneration process

[0007] In view of the shortcomings and defects of the existing low-temperature methanol washing method, which have long process flow, large equipment investment, small absorption capacity and large circulation volume of absorbent in the propylene carbonate method, high cost and easy polymerization loss of the polyethylene glycol dimethyl ether method, The inventor proposed a decarburization process using dimethyl carbonate as an absorbent (publication number CN101254388, a decarburization process using dimethyl carbonate as an absorbent), which can effectively simplify the process and reduce costs

However, the freezing point of dimethyl carbonate is relatively high (2°C). When used at a lower temperature in order to enhance the absorption effect, there will be a problem that the viscosity of dimethyl carbonate will increase rapidly or solidify, which will affect its use effect.

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