Study on coke dissolution loss reaction and its mechanism based on molecular dynamics simulations

doi:10.11949/0438-1157.20230207

Abstract

Abstract:

In order to study the coke dissolution loss reaction and its mechanism at the molecular level, a molecular model of coke containing graphitized carbon and non-graphitized carbon was constructed by molecular dynamics and first principles. The accuracy of the model was verified by comparing the true density of the molecular model. The influence of charge density and pore structure on the coke dissolution loss reaction was analyzed, and the mechanism of the reaction was also discussed. The results show that the true density of the model is within the range of the measured true density of coke. The higher the graphitization degree of coke, the smaller the charge density around carbon atoms, and the lower the degree of dissolution loss reaction. The experimental results are similar to the simulation results. CO₂ is mainly diffused in pores above 50 Å, with the lowest diffusion activation energy (131.24 kJ /mol), while it is mainly adsorbed in pores below 2 Å, with the highest adsorption energy (-192.54 kJ/mol). The mechanism of coke dissolution loss reaction includes the cracking reaction of graphitized carbon and non-graphitized carbon atoms, the isomerization reaction between two kinds of carbon atoms and the oxidation reaction between two kinds of carbon atoms and CO₂. In the process of oxidation reaction, the ketene structure generated by the reaction of two kinds of carbon atom and CO₂ will be cracked into CO due to its instability, which completes the reaction process.

Key words: coke, dissolution loss reaction, mechanism, molecular simulation, charge density, pore diameter, adsorption

摘要：

为从分子层面研究焦炭溶损反应及其机理，借助分子动力学和第一性原理构建了一种包含石墨化碳和非石墨化碳的焦炭分子模型，研究了电荷密度和孔径大小对焦炭溶损反应及其机理的影响，并通过实验对模拟结果加以验证。结果表明，所建模型真密度在焦炭实测密度范围内；焦炭石墨化程度越高，碳原子周边电荷密度越小，其溶损反应程度越低，实验结果与模拟结果相近；CO₂在孔径大于50 Å（1 Å=1×10^-10 m）气孔内以扩散为主，其扩散表观活化能最小，为131.24 kJ/mol；在孔径小于2 Å气孔内以吸附为主，其吸附能的绝对值最大，为192.54 kJ/mol；焦炭溶损反应机理包括焦炭分子生成石墨化碳和非石墨化碳原子的裂解反应、碳原子之间的异构化反应以及碳原子与CO₂的氧化反应，在氧化反应过程中，碳原子与CO₂反应生成的烯酮式结构会因其稳定性差裂解成CO，完成反应过程。

关键词: 焦炭, 溶损反应, 机理, 分子模拟, 电荷密度, 孔径, 吸附

CLC Number:

TQ 526.1

Ji CHEN, Ze HONG, Zhao LEI, Qiang LING, Zhigang ZHAO, Chenhui PENG, Ping CUI. Study on coke dissolution loss reaction and its mechanism based on molecular dynamics simulations[J]. CIESC Journal, 2023, 74(7): 2935-2946.

陈吉, 洪泽, 雷昭, 凌强, 赵志刚, 彭陈辉, 崔平. 基于分子动力学的焦炭溶损反应及其机理研究[J]. 化工学报, 2023, 74(7): 2935-2946.

Figures/Tables 17

References 40

1	吕青青, 周俊兰, 王光辉, 等. 高炉风口焦炭的形貌与冶金行为[J]. 钢铁, 2021, 56(10): 45-53.
	Lv Q Q, Zhou J L, Wang G H, et al. Morphology and metallurgical behavior of coke at tuyere of blast furnace[J]. Iron and Steel, 2021, 56(10): 45-53.
2	Wang M C, Wei G S, Yang S F, et al. Effect of alkali (K/Na) metal vapor on the metallurgical properties of coke in CO₂-O₂-N₂ mixed atmosphere[J]. Energy, 2022, 257: 124748.
3	Wang Q, Guo R, Zhao X F, et al. A new testing and evaluating method of cokes with greatly varied CRI and CSR[J]. Fuel, 2016, 182: 879-885.
4	Huang J C, Guo R, Wang Q, et al. Coke solution-loss degradation model with non-equimolar diffusion and changing local pore structure[J]. Fuel, 2020, 263: 116694.
5	Kumar D, Saxena V K, Tiwari H P, et al. Variability in metallurgical coke reactivity index (CRI) and coke strength after reaction (CSR): an experimental study[J]. ACS Omega, 2022, 7(2): 1703-1711.
6	Klika Z, Serenčíšová J, Kolomazník I, et al. Prediction of CRI and CSR of cokes by two-step correction models for stamp-charged coals—statistical analysis[J]. Fuel, 2020, 262: 116623.
7	Zhao J, Zuo H B, Ling C, et al. Microstructure evolution of coke under CO₂ and H₂O atmospheres[J]. Journal of Iron and Steel Research International, 2020, 27(7): 743-754.
8	Hilding T, Gupta S, Sahajwalla V, et al. Degradation behaviour of a high CSR coke in an experimental blast furnace: effect of carbon structure and alkali reactions[J]. ISIJ International, 2005, 45(7): 1041-1050.
9	Wang W, Dai B W, Xu R S, et al. The effect of H₂O on the reactivity and microstructure of metallurgical coke[J]. Steel Research International, 2017, 88(8): 1700063.
10	Niu Q, Cheng S S, Xu W X, et al. Analysis of the coke particle size distribution and porosity of deadman based on blast furnace hearth dissection[J]. ISIJ International, 2019, 59(11): 1997-2004.
11	黄逸群, 张缦, 单露, 等. 干馏条件对油页岩半焦孔隙结构的影响[J]. 化工学报, 2017, 68(10): 3870-3876.
	Huang Y Q, Zhang M, Shan L, et al. Effects of retorting conditions on pore structure of oil shale semi coke[J]. CIESC Journal, 2017, 68(10): 3870-3876.
12	崔平, 张磊, 杨敏, 等. 焦炭溶损反应动力学及其模型研究[J]. 燃料化学学报, 2006, 34(3): 280-284.
	Cui P, Zhang L, Yang M, et al. Study on kinetics and model of coke loss reaction with CO₂ in blast furnace[J]. Journal of Fuel Chemistry and Technology, 2006, 34(3): 280-284.
13	丁子昭. 焦炭溶损反应机理的分子动力学研究[D]. 唐山: 华北理工大学, 2021.
	Ding Z Z. Molecular dynamics study on the reaction mechanism of coke dissolution loss[D]. Tangshan: North China University of Science and Technology, 2021.
14	Li K J, Zhang H, Li G Y, et al. ReaxFF molecular dynamics simulation for the graphitization of amorphous carbon: a parametric study[J]. Journal of Chemical Theory and Computation, 2018, 14(5): 2322-2331.
15	田妍. 平遥焦炭微观结构的分子动力学研究[D]. 唐山: 华北理工大学, 2020.
	Tian Y. Molecular dynamics study on microstructure of Pingyao coke[D]. Tangshan: North China University of Science and Technology, 2020.
16	Li K J, Li H T, Sun M M, et al. Atomic-scale understanding about coke carbon structural evolution by experimental characterization and ReaxFF molecular dynamics[J]. Energy & Fuels, 2019, 33(11): 10941-10952.
17	Marsusi F, Drummond N D, Verstraete M J. The physics of single-side fluorination of graphene: DFT and DFT + U studies[J]. Carbon, 2019, 144: 615-627.
18	郑默, 李晓霞. ReaxFF MD模拟揭示的煤热解挥发分自由基反应的竞争与协调[J]. 化工学报, 2022, 73(6): 2732-2741.
	Zheng M, Li X X. Revealing reaction compromise in competition for volatile radicals during coal pryolysis via ReaxFF MD simulation[J]. CIESC Journal, 2022, 73(6): 2732-2741.
19	袁妮妮, 郭拓, 白红存, 等. 化学链燃烧过程Fe₂O₃/Al₂O₃载氧体表面CH₄反应:ReaxFF-MD模拟[J]. 化工学报, 2022, 73(9): 4054-4061.
	Yuan N N, Guo T, Bai H C, et al. Reaction process of CH₄ on the surface of Fe₂O₃/Al₂O₃ oxygen carrier in chemical looping combustion: ReaxFF-MD simulation[J]. CIESC Journal, 2022, 73(9): 4054-4061.
20	Ge Z P, Wang Y. Estimation of nanodiamond surface charge density from zeta potential and molecular dynamics simulations[J]. The Journal of Physical Chemistry B, 2017, 121(15): 3394-3402.
21	Yang K Z, Yang G, Wu J Y. Insights into the enhancement of CO₂ adsorption on faujasite with a low Si/Al ratio: understanding the formation sequence of adsorption complexes[J]. Chemical Engineering Journal, 2021, 404: 127056.
22	Chenoweth K, van Duin A C T, Dasgupta S, et al. Initiation mechanisms and kinetics of pyrolysis and combustion of JP-10 hydrocarbon jet fuel[J]. The Journal of Physical Chemistry A, 2009, 113(9): 1740-1746.
23	马生贵, 田博文, 周雨薇, 等. 氮掺杂Stone-Wales缺陷石墨烯吸附H₂S的密度泛函理论研究[J]. 化工学报, 2021, 72(9): 4496-4503.
	Ma S G, Tian B W, Zhou Y W, et al. DFT study of adsorption of H₂S on N-doped stone-wales defected graphene[J]. CIESC Journal, 2021, 72(9): 4496-4503.
24	玄伟伟, 董彦吾, 王海轮. 基于ReaxFF-MD和DFT的废旧PP塑料水蒸气气化机理研究[J]. 化工学报, 2022, 73(11): 5251-5262.
	Xuan W W, Dong Y W, Wang H L. Study on the steam gasification mechanism of waste PP plastics based on ReaxFF-MD and DFT methods[J]. CIESC Journal, 2022, 73(11): 5251-5262.
25	俞夏琪, 冯格, 赵金燕, 等. 基体(TDI-TMP-T313)与氧化剂(AP)相互作用的第一性原理研究[J]. 化工学报, 2022, 73(8): 3511-3517.
	Yu X Q, Feng G, Zhao J Y, et al. A first-principles study of the interaction between TDI-TMP-T313 and AP[J]. CIESC Journal, 2022, 73(8): 3511-3517.
26	刘佳, 姜桂元, 赵震, 等. Pt/TiO₂/ZSM-5催化剂的制备及其催化转化正丁烷[J]. 化工学报, 2016, 67(8): 3363-3373.
	Liu J, Jiang G Y, Zhao Z, et al. Preparation of Pt/TiO₂/ZSM-5 catalyst for catalytic conversion of n-butane[J]. CIESC Journal, 2016, 67(8): 3363-3373.
27	Lei Z, Jiang J, Zhu G L, et al. Investigate the adsorption behavior of CO₂ on char-inorganic compound model for coal gasification[J]. Energy & Fuels, 2016, 30(2): 1287-1293.
28	Mori A, Kubo S, Kudo S, et al. Preparation of high-strength coke by carbonization of hot-briquetted Victorian brown coal[J]. Energy & Fuels, 2012, 26(1): 296-301.
29	李佳, 梁贞菊, 王照亮, 等. 不同分子模型对甲烷水合物分解微观特性表征[J]. 化工学报, 2020, 71(3): 955-964.
	Li J, Liang Z J, Wang Z L, et al. Characterization of microscopic nature of methane hydrate decomposition by different molecular models[J]. CIESC Journal, 2020, 71(3): 955-964.
30	Savvatimskiy A I. Measurements of the melting point of graphite and the properties of liquid carbon (a review for 1963—2003)[J]. Carbon, 2005, 43(6): 1115-1142.
31	Wang X Y, Han T C, Fu L Y. Anisotropic elastic properties of montmorillonite with different layer charge densities and layer charge distributions through molecular dynamic simulation[J]. Frontiers in Earth Science, 2022, 10: 854816.
32	Peng C L, Song L L, Wang L, et al. Effect of surface charge distribution of phosphorus-doped MoS₂ on hydrogen evolution reaction[J]. ACS Applied Energy Materials, 2021, 4(5): 4887-4896.
33	Zhao H M, Wu M M, Wang Q, et al. Effects of charging and doping on orbital hybridizations and distributions in TiO₂ clusters[J]. Physica B: Condensed Matter, 2011, 406(22): 4322-4326.
34	Yan S S, Chen H R, Zhu H N, et al. Enhanced adsorption of bio-oil on activated biochar in slurry fuels and the adsorption selectivity[J]. Fuel, 2023, 338: 127224.
35	Taheri Z, Pour A N. Studying of the adsorption and diffusion behaviors of methane on graphene oxide by molecular dynamics simulation[J]. Journal of Molecular Modeling, 2021, 27(2): 59.
36	Furuya K, Hama T, Oba Y, et al. Diffusion activation energy and desorption activation energy for astrochemically relevant species on water ice show no clear relation[J]. The Astrophysical Journal Letters, 2022, 933(1): L16.
37	Li B, Li X, Gao W, et al. An effective scheme to determine surface energy and its relation with adsorption energy[J]. Acta Materialia, 2021, 212: 116895.
38	Lei Z, Yan J C, Xie R L, et al. Catalysis mechanism of solution loss reaction of metallurgical coke in blast furnace: experimental and modeling study[J]. Fuel, 2021, 290: 120025.
39	Tan M, Li T, Wang Z H, et al. Investigation on adsorption of sodium fluoro-aluminates on graphite by density functional theory[J]. Journal of Molecular Liquids, 2023, 373: 121252.
40	湛文龙, 孙崇, 余盈昌, 等. 高炉焦炭石墨化过程中的微观组织和冶金性能演变[J]. 工程科学学报, 2018, 40(6): 690-696.
	Zhan W L, Sun C, Yu Y C, et al. Evolution of coke microstructure and metallurgical properties during graphitization in a blast furnace[J]. Chinese Journal of Engineering, 2018, 40(6): 690-696.

样品编号	JM/kg	FM/kg	1/3JM/kg	SM/kg	QM/kg	A_d/%	V_daf/%	S_t,d/%	G	Y/mm
c1	28	11	17	7	7	9.30	28.27	0.83	80	16.4
c2	28	11	15	7	9	9.42	28.85	0.84	79	16.1
c3	28	11	13	7	11	9.61	29.34	0.86	76	15.6
c4	28	11	10	7	14	9.74	29.78	0.89	77	15.2

样品编号	JM/kg	FM/kg	1/3JM/kg	SM/kg	QM/kg	A_d/%	V_daf/%	S_t,d/%	G	Y/mm
c1	28	11	17	7	7	9.30	28.27	0.83	80	16.4
c2	28	11	15	7	9	9.42	28.85	0.84	79	16.1
c3	28	11	13	7	11	9.61	29.34	0.86	76	15.6
c4	28	11	10	7	14	9.74	29.78	0.89	77	15.2

样品编号	性质/%（质量分数）
样品编号	A_d	V_daf	M₄₀	M₁₀	CRI	CSR
c1	12.59	1.06	78.2	6.3	22.9	60.7
c2	12.61	1.08	76.7	6.5	23.3	60.2
c3	12.65	1.07	75.2	6.7	23.8	59.9
c4	12.73	1.05	74.3	6.7	24.3	59.4

样品编号	性质/%（质量分数）
样品编号	A_d	V_daf	M₄₀	M₁₀	CRI	CSR
c1	12.59	1.06	78.2	6.3	22.9	60.7
c2	12.61	1.08	76.7	6.5	23.3	60.2
c3	12.65	1.07	75.2	6.7	23.8	59.9
c4	12.73	1.05	74.3	6.7	24.3	59.4

样品编号	含量/%（质量分数）
样品编号	C_d	H_d	O_d^①	N_d	S_d	P_d
c1	97.04	0.56	0.49	1.11	0.79	0.01
c2	97.18	0.49	0.54	0.99	0.78	0.02
c3	97.20	0.51	0.50	1.02	0.76	0.01
c4	97.17	0.54	0.48	1.04	0.75	0.02