我国关闭矿井数量逐年增加，采空区和废弃巷道硐室可为封存CO₂提供地质空间，煤层中含有大量CH₄，向采空区注入CO₂，其与CH₄以及N₂之间存在竞争吸附行为，明确N₂、CH₄、CO₂间竞争吸附的规律及其作用机理对于煤矿采空区CO₂封存理论具有一定指导意义。本文选取6个煤样，采用自主研发的多组分气体竞争吸附装置，主要基于穿透曲线法，研究煤对N₂/CH₄/CO₂多组分气体的竞争吸附动力学规律以及温度、压力、气体组分配比、孔隙等因素对竞争吸附的影响。

通过低温N₂吸附法、CO₂吸附法得到6个煤样的孔隙参数，得出大柳塔（DLT）、硫磺沟（LHG）煤样的比表面积较大，平均孔径和最可几孔径较小，山阳（SY）和屯宝（TB）煤样比表面积最小。DLT和LHG煤样N₂吸附等温线滞后环为H2型，二者孔隙形态主要为墨水瓶状，黄陵（HL）、小庄（XZ）、SY和TB煤样的滞后环为H3，孔形主要是平板狭缝及开放毛细孔。LHG和DLT煤样微孔最为发育，SY和TB煤样内的介孔最发育，微孔发育程度低。微孔较发育的DLT和LHG煤样对气体的吸附能力强、吸附量大，在竞争吸附中对CO₂吸附选择性更强，竞争吸附发生更充分，而微孔发育程度低的SY、TB煤样中竞争吸附发生不充分，只有N₂被置换出，CH₄无法被置换出来。

通过不同温度、压力、组分配比的二/三组分气体竞争吸附实验，得出随着温度升高，煤样吸附量减少，升温能促进竞争吸附发生，加强CO₂优先吸附性；升高压力，煤样吸附量增加，升高压力会抑制竞争吸附发生，减弱CO₂的优先吸附性；若N₂/CH₄/CO₂三组分气体中CO₂的配比保持不变，N₂和CH₄的吸附体积、吸附量和吸附比例均与其组分配比大小呈正相关，并且若三组分气体中CH₄占比越大，煤样能吸附CO₂的量也越多，吸附三组分气体的总量也越多。

选用Yoon-Nelson、Thomas、Clark 3种动力学模型对实验数据拟合，传质速率常数k、k_T和r皆有N₂＞CH₄＞CO₂的规律。随着温度或压力升高，各组分k值、k_T值、r值均变大，说明升高温度或压力会提高气体传质速率。此外，各组分的吸附量q_T、Clark常数A皆有CO₂＞CH₄＞N₂的规律，表明煤样对三种气体的吸附能力为CO₂＞CH₄＞N₂，

升高温度、压力以及某组分在多组分气体中的占比，均会使该组分的q_T和A增大，且微孔更发育的煤样各组分的q_T和A值更大。

通过分析实验数据，对采空区CO₂封存技术与安全储碳进行了工程应用方面的展望。本研究相关结论可为完善煤对多组分气体竞争吸附理论、废弃煤层CO₂封存方法提供一定的理论依据。

The number of closed mines in China has increased in recent years. The goaf and abandoned roadway chambers can provide geological space for CO₂ storage. There is a large amount of CH₄ in the coal seam. When CO₂ is injected into the goaf, there is a competitive adsorption behavior between them and N₂. Clarifying the law and mechanism of competitive adsorption among N₂, CH₄, and CO₂ has guiding significance for the theory of CO₂ storage in goafs. In this paper, six coal samples were selected. And a multi-component gas competitive adsorption device was built. Mainly based on the breakthrough curve method, the competitive adsorption kinetic law of N₂/CH₄/CO₂ multi-component gas and the effects of temperature, pressure, gas distribution ratio, porosity on competitive adsorption were obtained.

The pore parameters of coal samples were measured by low-temperature N₂ adsorption and CO₂ adsorption method. It was found that the specific surface area of DLT and LHG coal samples was larger, the average pore size and the most probable pore size were smaller. The specific surface area of SY and TB coal samples was the smallest. The hysteresis loop of DLT and LHG is H2 type, the pore morphology of them is mainly ink bottle. The hysteresis loop of HL, XZ, SY and TB samples is H3, the pore shape is mainly flat slit and open pores. LHG and DLT have the most developed micropores. SY and TB have the most developed mesopores, and the degree of micropores development is low. DLT and LHG with relatively developed micropores have strong adsorption capacity for gas. They also have stronger selectivity for CO₂ adsorption in competitive adsorption, competitive adsorption occurs more fully. However, competitive adsorption in SY and TB with low micropore development is not sufficient. Only N₂ is replaced, CH₄ cannot be replaced.

Through competitive adsorption experiments of two or three component gases at different temperatures, pressures, and distribution ratios, it was found that the adsorption capacity of coal samples decreased with the increase of temperature. The increase of temperature can promote the competitive adsorption and enhance the preferential adsorption of CO₂. Increasing the pressure will increase the adsorption capacity of coal samples. It also will inhibit competitive adsorption and weaken the preferential adsorption of CO₂. If the ratio of CO₂ in the three-component gas remains unchanged, the adsorption volume, adsorption amount and adsorption ratio of N₂ and CH₄ are positively correlated with their component distribution ratio. If the proportion of CH₄ in the three-component gas is larger, the more CO₂ and three-component gas can be adsorbed by the coal sample.

Yoon-Nelson, Thomas and Clark kinetic models were selected to fit the experimental data. Mass transfer rate constants k, k_T and r all have the rule of N₂>CH₄>CO₂. With the increase of temperature or pressure, the k, k_T and r values of each component become larger, indicating that the increase of temperature or pressure will increase the gas mass transfer rate. In addition, the adsorption capacity q_T and Clark constant A of each component have the rule of CO₂>CH₄>N₂, indicating that the adsorption capacity of coal samples for three gases is CO₂>CH₄>N₂. Increasing temperature, pressure and the proportion of a component in multi-component gases will increase the q_T and A of this component. Also, the q_T and A values of coal samples with more developed micropores are higher.

By analyzing experimental data, the engineering application prospects of CO₂ storage technology and safe carbon storage in goaf were presented. The relevant conclusions of this study can provide a theoretical basis for improving the theory of competitive adsorption of coal to multicomponent gases and the method of CO₂ storage in abandoned coal seams.