Preparation method of coal-based carbon molecular sieve

Abstract

The invention discloses a preparation method of a coal-based carbon molecular sieve, wherein the preparation method mainly includes the following steps: (1) screening coal-based activated carbon withsuitable pore size; (2) depositing with a methane deposition agent with different concentrations, and adjusting the pore size of coal-based activated carbon to prepare carbon molecular sieve samples;and (3) preparing a carbon molecular sieve sample with large nitrogen adsorption capacity and small methane adsorption capacity, wherein the carbon molecular sieve sample is advantageous to separationin kinetics. The coal-based activated carbon has the advantages of wide pore size range, wide source and low price. The deposited gas is mixed gas of inert gas and methane. The deposited gas has no pollution to the environment. The nitrogen adsorption capacity of the prepared product is large and the equilibrium separation coefficient is small, and dynamic separation of nitrogen and methane is facilitated.

Description

technical field [0001] The patent of the present invention relates to a method for preparing coal-based carbon molecular sieves. Coal-based carbon molecular sieves with sieving effects are prepared by using coal-based activated carbon with a wide pore size distribution range and low cost, which belongs to the field of inorganic materials. Background technique [0002] PSA gas separation is realized in two ways: equilibrium effect and kinetic effect. The molecular dynamic diameters of methane and nitrogen are 0.380nm and 0.364nm respectively. The pore size distribution of activated carbon is wide, and the force with methane is greater than that of nitrogen during adsorption. However, since both are non-polar molecules and the dynamic diameters are different Smaller, the adsorption separation coefficient is not large, and when the equilibrium effect is used to separate methane and nitrogen, the separation is difficult and the energy consumption is large. At present, carbon mo...

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Problems solved by technology

[0006] Chinese patent CN101804979A discloses a coal-based carbon molecular sieve and its preparation method. Organic matter such as benzene and toluene are mainly used as pore-adjusting agents. The maximum adsorption capacity of nitrogen in the prepared sample is 5.95ml, the maximum adsorption capacity of methane is 17.1ml, and the equilibrium separation coefficient is about 3, and the adsorption capacity of nitrogen is relatively low, and the adsorption capacity of methane is large, which is mainly biased towards equilibrium adsorption, which increases energy consumption in the dynamic adsorption separation project of pressure swing adsorption, which is not conducive to the dynamic separation of methane and nitrogen gas mixture

[0007] Chinese patent 105692613A discloses a method for preparing carbon molecular sieves for methane purification, mainly using aromatic hydrocarbons such as benzene, and adjusting the pore size of the molecular sieve to 0.36-0.40nm. It does not describe in detail the adjustment of the adsorption capacity of carbon molecular sieves for nitrogen and methane, and does not point out the precursor body selection

[0008] The preparation process of coal-based carbon molecular sieve in the existing invention is relatively complicated, and the suitable pore size range of the precursor of coal-based carbon molecular sieve has not been pointed out, and the nitrogen adsorption amount is relatively low, the methane adsorption amount is relatively large, and the kinetic separation effect is poor

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