Experimental Measurements and Molecular Simulation of Carbon Dioxide Adsorption on Carbon Surface
Experimental Measurements and Molecular Simulation of Carbon Dioxide Adsorption on Carbon Surface
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DOI：
10.2118/210264-ms
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发表时间：
2022-09
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影响因子：
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通讯作者：
I. Gomaa;Javier Guerrero;Z. Heidari;D. Espinoza
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文献类型：
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作者：
I. Gomaa;Javier Guerrero;Z. Heidari;D. Espinoza
在枯竭的气藏中地质储存二氧化碳（CO2）是减少全球碳排放的一种经济有效的解决方案。储层岩石的表面化学性质、压力、温度和含水率是决定CO2吸附能力和储存机制的关键因素。页岩气储层是该应用的理想选择。然而，CO2与有机含量的相互作用仍需进一步研究。本文的目的是：(i)实验研究压力和温度对活性炭吸附CO2能力的影响，（ii）利用蒙特卡罗分子模型量化CO2与活性炭表面之间的纳米级界面相互作用，(3)量化不同温度和地球化学条件下，活性炭- co2体系吸附等温线与页岩气实际二氧化碳吸附量的相关性。活性炭被用作干酪根的替代品。目的是为了更好地了解页岩气地层中二氧化碳的注入和储存行为。我们进行了实验测量和大规范蒙特卡罗（GCMC）模拟二氧化碳吸附在活性炭上。实验工作包括使用纯二氧化碳气体测量活性炭的高压吸附能力。随后，我们进行了一系列的GCMC模拟，计算活性炭对CO2的吸附能力，以验证实验结果。所述模拟活性炭结构由石墨片组成，石墨片之间的距离等于活性炭样品的平均实际孔径。计算了不同压力下各温度值的吸附等温线，并建立了吸附等温线模型。从能量和动力学的角度来看，活性炭对CO2的吸附是有利的。这是由于存在广泛的微孔到中孔尺寸，可以容纳大量的二氧化碳颗粒。实验结果表明，混合气体的过量吸附结果介于纯组分的结果之间。仿真结果与实验结果吻合较好。吸附CO2的强度取决于活性炭的表面化学性质和孔径大小。一旦在纳米级网络中建立了强吸附位点，即使在非常低的压力下，气体吸附也是由孔隙宽度而不是化学成分决定的。本文的研究结果为页岩气储层中影响CO2吸附和储存的参数提供了新的见解，这对于建立纯有机碳上CO2吸附的独立代表性模型至关重要。
Geological storage of carbon dioxide (CO2) in depleted gas reservoirs represents a cost-effective solution to mitigate global carbon emissions. The surface chemistry of the reservoir rock, pressure, temperature, and moisture content are critical factors that determine the CO2 adsorption capacity and storage mechanisms. Shale-gas reservoirs are good candidates for this application. However, the interactions of CO2 and organic content still need further investigation. The objectives of this paper are to (i) experimentally investigate the effect of pressure and temperature on the CO2 adsorption capacity of activated carbon, (ii) quantify the nanoscale interfacial interactions between CO2 and the activated carbon surface using Monte Carlo molecular modeling, and (iii) quantify the correlation between the adsorption isotherms of activated carbon-CO2 system and the actual carbon dioxide adsorption on shale-gas rock at different temperatures and geochemical conditions. Activated carbon is used as a proxy for kerogen. The objectives aim at obtaining a better understanding of the behavior of CO2 injection and storage into shale-gas formations. We performed experimental measurements and Grand Canonical Monte Carlo (GCMC) simulations of CO2 adsorption onto activated carbon. The experimental work involved measurements of the high-pressure adsorption capacity of activated carbon using pure CO2 gas. Subsequently, we performed a series of GCMC simulations to calculate CO2 adsorption capacity on activated carbon to validate the experimental results. The simulated activated carbon structure consists of graphite sheets with a distance between the sheets equal to the average actual pore size of the activated carbon sample. Adsorption isotherms were calculated and modeled for each temperature value at various pressures. The adsorption of CO2 on activated carbon is favorable from the energy and kinetic point of view. This is due to the presence of a wide micro to meso pore sizes that can accommodate a large amount of CO2 particles. The results of the experimental work show that excess adsorption results for gas mixtures lie in between the results for pure components. The simulation results agree with the experimental measurements. The strength of CO2 adsorption depends on both surface chemistry and pore size of activated carbon. Once strong adsorption sites within nanoscale network are established, gas adsorption even at very low pressure is governed by pore width rather than chemical composition. The outcomes of this paper provides new insights about the parameters affecting CO2 adsorption and storage in shale-gas reservoirs, which is critical for developing standalone representative models for CO2 adsorption on pure organic carbon.