本文選題：多孔晶體　切入點：GCMC模擬　出處：《東北師范大學(xué)》2017年碩士論文

【摘要】：多孔晶體是一種由相互貫通或封閉的孔洞構(gòu)成網(wǎng)絡(luò)結(jié)構(gòu)的晶體材料,是多孔材料的重要分支。由于多孔晶體在氣體存儲、催化、能量轉(zhuǎn)換、能量存儲、光電學(xué)、氣體分離、超疏水界面等領(lǐng)域的廣泛應(yīng)用,在過去的十多年里,人們對多孔晶體領(lǐng)域的興趣大增,一些新型的多孔晶體也在不斷引起人們的關(guān)注。如,金屬有機(jī)骨架,共價有機(jī)骨架,多孔共軛骨架,微孔分子晶體等。計算模擬是研究這類材料的一種重要手段,通過計算模擬能夠設(shè)計多孔結(jié)構(gòu),模擬氣體在多孔材料中的吸附行為,對結(jié)構(gòu)進(jìn)行篩選等。與快速發(fā)展的實驗工作相比,計算模擬研究相對滯后,主要表現(xiàn)在缺乏合適力場而導(dǎo)致的精度降低。在此,我們通過多尺度理論模擬,設(shè)計多孔晶體并對多孔晶體的氣體吸附性能進(jìn)行研究:1.以近期合成的1,4-二亞苯基-2,5-二噻吩環(huán)為基礎(chǔ),我們設(shè)計了一系列納米多孔分子晶體(CPTs),采用基于色散矯正的雙雜化密度泛函理論的派生力場,通過巨正則蒙特卡洛模擬了其吸附性能。采用足夠多的準(zhǔn)確的參考態(tài)數(shù)據(jù)產(chǎn)生力場,證實了模擬的準(zhǔn)確性。結(jié)果顯示,CPTs可調(diào)的孔徑使它們非常適合CO和H_2的存儲,非常有趣的是,在一定條件下,也是潛在的H_2凈化候選材料。多尺度模擬給CPTs在氣體存儲和凈化方面的應(yīng)用提供了理論依據(jù)。2.設(shè)計了一系列新型鎂-卟啉基類金剛石結(jié)構(gòu)多孔有機(jī)骨架,命名為POF-Mgs,采用基于第一性原理的派生力場,通過巨正則蒙特卡洛模擬了CO_2、H_2、N_2和H_2O氣體在POF-Mgs中的吸附。第一性原理計算中,采用色散校正的雙雜化密度泛函B2PLYPD3描述骨架和氣體之間的相互作用。擬合得到的力場和第一性原理能量數(shù)據(jù)吻合良好,證實了力場的可靠性。結(jié)果表明,在適當(dāng)?shù)臈l件下,[1,2]POF-Mgs是純化氫氣的潛在候選材料。此外,我們的模擬表明,少量水的存在(≤0.01 kPa)對CO_2的吸附?jīng)]有太大的影響,但當(dāng)H_2O的分壓較高時(≥0.1 kPa)會導(dǎo)致CO_2吸附量顯著降低。3.在實驗上制備的金屬有機(jī)骨架PCN-600(Co)中,分別用鹵素取代其苯環(huán)及卟啉上的氫原子,通過巨正則蒙特卡洛模擬這一系列孔材料對氣體(CO_2、SO_2、CH_4、CO、H_2和N_2)的吸附。結(jié)果顯示,鹵素取代后的結(jié)構(gòu)對SO_2和CO_2的吸附量均有非常明顯的提高,對CH_4,CO,N_2和H_2的吸附量反而降低,這表明鹵素取代后的孔材料在氣體分離方面具有潛在的應(yīng)用。之后進(jìn)行的選擇性探究表明,PCN-Co-F-F在氣體存儲和分離方面都有很大的潛力,尤其在氫氣純化方面。
[Abstract]:Porous crystal is a kind of crystal material which is made up of interpenetrating or closed holes. It is an important branch of porous material, because porous crystal is used in gas storage, catalysis, energy conversion, energy storage, photoelectricity, gas separation. With the wide application of superhydrophobic interface and other fields, the interest in porous crystal field has increased greatly in the past decade, and some new porous crystals are attracting more and more attention, such as metal organic skeleton, covalent organic skeleton, metal organic skeleton, covalent organic skeleton, metal organic skeleton, covalent organic skeleton, metal organic skeleton, covalent organic skeleton, and so on. Porous conjugate skeleton, microporous molecular crystal and so on. Computational simulation is an important means to study this kind of material. The porous structure can be designed by computer simulation, and the adsorption behavior of gas in porous material can be simulated. Compared with the rapid development of experimental work, the computational simulation study is relatively lagging, mainly due to the lack of appropriate force field, resulting in lower accuracy. In this case, we use multi-scale theoretical simulation. The gas adsorption properties of porous crystals were studied. 1. Based on the recently synthesized 1 ~ (4) -diphenyl -2o _ (5) -dithiophene ring, We have designed a series of nano-porous molecular crystals (CPTsN), using the derived force field based on the double hybrid density functional theory (DFT), which is based on dispersion correction. The adsorption performance is simulated by means of the grand canonical Monte Carlo. The accuracy of the simulation is confirmed by using enough accurate reference state data to generate force field. The results show that the CPTs have adjustable pore sizes that make them very suitable for CO and H-2 storage. And what's interesting is, under certain conditions, Multi-scale simulation provides a theoretical basis for the application of CPTs in gas storage and purification. 2. A series of novel porous organic frameworks of MgO-porphyrin diamond-like carbon structure have been designed. Named POF-MgsA derived force field based on first principles is used to simulate the adsorption of CO2H2N2 and H2O gases in POF-Mgs by means of the grand canonical Monte Carlo method. The interaction between the skeleton and the gas is described by using the dispersion corrected dual hybrid density functional B2PLYPD3. The fitted force field is in good agreement with the first principle energy data, which proves the reliability of the force field. In addition, our simulation shows that the presence of a small amount of water (鈮，

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