DETA接枝氧化石墨烯吸附二氧化碳的量子化学研究

Quantum chemical study on carbon dioxide adsorption by DETA grafted graphene oxide

氧化石墨烯枝接有机胺是极具潜力的CO_(2)吸附剂,为促进GO-DETA的研发和设计,亟需对其微观反应机理进行详细深入的研究。本文采用量子化学方法较为详细地研究了DETA接枝氧化石墨烯捕获CO_(2)的微观机理。首先,构建合理的吸附剂模型,并通过静电势分析发现,静电势负值较大处(-158.06 kJ/mol、-149.10 kJ/mol)是潜在的较好的吸附点位,量子化学计算也表明,在静电势负值较大处物理吸附能更大(-28.28 kJ/mol、-11.30 kJ/mol),进一步验证静电势负值较大处是较好的吸附点位。随后在最佳反应位点进行CO_(2)吸附量子化学计算。计算结果表明,DETA接枝氧化石墨烯具有较好的吸附CO_(2)性能,反应能垒为(172.9 kJ/mol、170.5 kJ/mol),而且气氛中H_(2)O有催化作用,吸附反应能垒显著降低,仅需37~56 kJ/mol。相比于羧基接枝DETA氧化石墨烯(-11.30 kJ/mol、56.5 kJ/mol),环氧基接枝DETA氧化石墨烯的物理吸附能和化学吸附能垒均有所下降,而且解吸附能垒(65.2 kJ/mol)高于反应能垒(37.1 kJ/mol),这有利于反复吸附和解吸附,有利于吸附剂的循环重复利用。因此,环氧基联DETA氧化石墨烯是更优的CO_(2)吸附剂。对于DETA-GO吸附捕集CO_(2),将羟基和羧基转换为环氧基是其关键。本文研究加深了氧化石墨烯接枝有机胺吸附CO_(2)的微观机理理解,将有助于基于氧化石墨烯固态CO_(2)吸附剂的研发和设计。

Graphene oxide branched organic amine is a potential CO_(2) adsorbent.In order to promote the development and design of DETA-GO,it is urgent to study its micro reaction mechanism in detail.In this paper,the micro mechanism of CO_(2) capture by DETA grafted graphene oxide was studied in detail by quantum chemical method.First,a reasonable adsorbent model was constructed,and through electrostatic potential analysis,it was found that the larger negative electrostatic potential(-37.76 kcal/mol,-35.67 kcal/mol)was a potential better adsorption site.Quantum chemical calculation also showed that the physical adsorption energy was larger(-28.28 kJ/mol,-11.30 kJ/mol)at the larger negative electrostatic potential,which further verified that the larger negative electrostatic potential was a better adsorption site.Then the quantum chemical calculation of CO_(2) adsorption was carried out at the optimal reaction site.The results show that DETA grafted graphene oxide has a good adsorption performance for CO_(2),and the reaction energy barrier is(172.9 kJ/mol,170.5 kJ/mol).Moreover,the H_(2)O in the atmosphere has a catalytic effect,and the adsorption reaction energy base is significantly lower,requiring only 37~56 kJ/mol.Compared with DETA-GOCA(-11.30 kJ/mol,56.5 kJ/mol),the physical adsorption energy and chemical adsorption energy barrier of DETA-GOEP are decreased,and the desorption energy barrier(65.2 kJ/mol)is slightly higher than the reaction energy barrier(37.1 kJ/mol),which is conducive to reverse adsorption and desorption,and is conducive to the recycling and reuse of adsorbents.DETA-GOEP is a better CO_(2) adsorbent.For the adsorption and capture of CO_(2) by DETA-GO,the conversion of hydroxyl and carboxyl groups to epoxy groups is the key.This study deepens the understanding of the micromechanism of CO_(2) adsorption by graphene oxide grafted organic amines,which will contribute to the development and design of solid CO_(2) adsorbents based on graphene oxide.