The pyrolysis of 5-HMF was investigated using density functional theory methods at B3LYP/6-31 G++(d, p) level. Two possible pyrolytic pathways were proposed and full optimization of the energy gradient for the structu...The pyrolysis of 5-HMF was investigated using density functional theory methods at B3LYP/6-31 G++(d, p) level. Two possible pyrolytic pathways were proposed and full optimization of the energy gradient for the structures of reactants, products, intermediates and transition states of various reactions was implemented. The standard kinetic parameters in each reaction pathway were calculated and the formation and evolution mechanism of main pyrolysis products were analyzed. Bond dissociation energies calculation results show that the bond dissociation energy of CH_3—OH of 5-HMF is the lowest and the order of all kinds of bond dissociation energy is CH_3—OH<C—H<CH_3 OH—C_(aromatic)<CHO—C_(aromatic)<C_(aromatic)—H. In pathway(1), the energy barrier of furfural is 322.8 kJ/mol, the energy barrier of 2-furfuryl alcohol is 375.4 kJ/mol; the energy barrier of furan-2,5-dicarbaldehyde is 496.1 kJ/mol; the energy barrier of 5-methyl furfural is 375.8 kJ/mol, and the energy barrier of 2-methyl furan is 375.8 kJ/mol. In pathway(2), the activation energy required for open-loop with H_2O is higher.展开更多
The action between imidazolinyl-quaternary-ammonium-salt(IQAS) molecule and Fe atom was studied, and the influence of the alkyl group connected with N atom of imidazoline ring on corrosion inhibition efficiency was ex...The action between imidazolinyl-quaternary-ammonium-salt(IQAS) molecule and Fe atom was studied, and the influence of the alkyl group connected with N atom of imidazoline ring on corrosion inhibition efficiency was explored. Quantum chemical methods, HF/6-31 G and HF/Lan L2 dz, were applied successively to calculate the parameters such as front molecular orbit energy of IQASⅠ-Ⅳ and chemical adsorption for IQASⅠ-Ⅳ and Fe atom. The corrosion inhibition efficiency was measured with the weight loss method of carbon steel samples in acidic solution and oil field sewage. Based on the theoretical analyses and experimental results, it is concluded that N-Fe coordination bond is formed between IQAS molecule and Fe atom, corrosion inhibition efficiency is decreased in the following order(from large to small): IQAS Ⅳ, IQAS Ⅲ, IQAS Ⅱ, IQASⅠ.展开更多
B3LYP/6-31G(d,p) method was used to investigate the catalytic cracking mechanism of biomass tar model compound.Phenol,toluene and benzene were selected as the tar model compounds and CaO was selected as the catalyst.T...B3LYP/6-31G(d,p) method was used to investigate the catalytic cracking mechanism of biomass tar model compound.Phenol,toluene and benzene were selected as the tar model compounds and CaO was selected as the catalyst.The pathways of tar compound radical absorbed by CaO were determined firstly through comparing enthalpy changes of the absorption,and then Mulliken population changes were analyzed.The results show that the absorption of tar model compound radical and CaO is an exothermic reaction.Formation of C—O—Ca is more easily than that of C—Ca—O and formation of Caromatic—Caromatic—Ca—O is more easily than that of Caromatic—C(O)—Ca—O.The C—C bond Mulliken populations in tar model compound radicals are reduced by 11.9%,10.5% and 15.5% in the case of a hydrogen atom removed,and those are 15.7%,14.3% and 16.3% in the case of two hydrogen atoms removed through the absorption of CaO.Catalytic ability of CaO acting on the tar model compound is in an order of phenol>benzene>toluene.展开更多
In order to investigate whether zinc atom is compatible with 1, 3, 3-trinitroazetidine(TNAZ) structure, TNAZ+Zn and 2 TNAZ+Zn composite systems have been considered within the constraints of density functional theory ...In order to investigate whether zinc atom is compatible with 1, 3, 3-trinitroazetidine(TNAZ) structure, TNAZ+Zn and 2 TNAZ+Zn composite systems have been considered within the constraints of density functional theory at the level of B3 LYP/6-31++G(d,p) and ωB97 X-D/6-31++G(D,P). In the case of TNAZ+Zn composite the both level of calculations resulted that one of the C-NO2 bonds of TNAZ undergoes bond cleavage. However, as the zinc content decreases by increasing the TNAZ content, C-NO2 bond elongation considerably decreases, although it is still longer than the similar bonds in 2 TNAZ+Zn composite in which zinc, by weight, is 7.14%. In all the cases the zinc atom acquires positive charge. The results indicate that the interfrontier molecular orbital energy gaps(HOMO-LUMO energy difference) of the composites decrease as the zinc content decreases.展开更多
The work addresses to the study of the molecular and crystal structure and properties of a new energyintensive compound 3,6-bis(2,2,2-trinitroethylnitramino)-1,2,4,5-tetrazine(NBTAT),first obtained by the authors in 2...The work addresses to the study of the molecular and crystal structure and properties of a new energyintensive compound 3,6-bis(2,2,2-trinitroethylnitramino)-1,2,4,5-tetrazine(NBTAT),first obtained by the authors in 2020.NBTAT compound crystallizes in the monoclinic system,space group P2(1)/n,density at room temperature 1.939 g/cm^(3).The energies of crystal packing and pairwise intermolecular interactions in NBTAT and its unnitrated analogue BTAT were calculated,and their comparative analysis was carried out.The enthalpy of formation of NBTAT molecules was calculated by quantum-chemical methods using Gaussian 09,and the enthalpy of formation of NBTAT in the solid phase(618 kJ/mol)was estimated.The energy capabilities of NBTAT as an oxidizer of solid composite propellants are estimated.It is shown that in metal-free compositions NBTAT is significantly superior to ammonium perchlorate(AP),dinitramide ammonium salt(ADN),HMX,BTAT at all stages of rocket systems,and is comparable to the superdense CL-20 yielding to the latter at the lower stages and slightly winning at the upper stages.展开更多
基金Project(51276023)supported by the National Natural Science Foundation of China
文摘The pyrolysis of 5-HMF was investigated using density functional theory methods at B3LYP/6-31 G++(d, p) level. Two possible pyrolytic pathways were proposed and full optimization of the energy gradient for the structures of reactants, products, intermediates and transition states of various reactions was implemented. The standard kinetic parameters in each reaction pathway were calculated and the formation and evolution mechanism of main pyrolysis products were analyzed. Bond dissociation energies calculation results show that the bond dissociation energy of CH_3—OH of 5-HMF is the lowest and the order of all kinds of bond dissociation energy is CH_3—OH<C—H<CH_3 OH—C_(aromatic)<CHO—C_(aromatic)<C_(aromatic)—H. In pathway(1), the energy barrier of furfural is 322.8 kJ/mol, the energy barrier of 2-furfuryl alcohol is 375.4 kJ/mol; the energy barrier of furan-2,5-dicarbaldehyde is 496.1 kJ/mol; the energy barrier of 5-methyl furfural is 375.8 kJ/mol, and the energy barrier of 2-methyl furan is 375.8 kJ/mol. In pathway(2), the activation energy required for open-loop with H_2O is higher.
基金Project (05A002) supported by Scientific Research Fundation of Hunan Provincial Education Depart ment project(04JJY40010) supported by the Natural Science Foundation of Hunan Province
文摘The action between imidazolinyl-quaternary-ammonium-salt(IQAS) molecule and Fe atom was studied, and the influence of the alkyl group connected with N atom of imidazoline ring on corrosion inhibition efficiency was explored. Quantum chemical methods, HF/6-31 G and HF/Lan L2 dz, were applied successively to calculate the parameters such as front molecular orbit energy of IQASⅠ-Ⅳ and chemical adsorption for IQASⅠ-Ⅳ and Fe atom. The corrosion inhibition efficiency was measured with the weight loss method of carbon steel samples in acidic solution and oil field sewage. Based on the theoretical analyses and experimental results, it is concluded that N-Fe coordination bond is formed between IQAS molecule and Fe atom, corrosion inhibition efficiency is decreased in the following order(from large to small): IQAS Ⅳ, IQAS Ⅲ, IQAS Ⅱ, IQASⅠ.
基金Project(51276023)supported by the National Natural Science Foundation of China
文摘B3LYP/6-31G(d,p) method was used to investigate the catalytic cracking mechanism of biomass tar model compound.Phenol,toluene and benzene were selected as the tar model compounds and CaO was selected as the catalyst.The pathways of tar compound radical absorbed by CaO were determined firstly through comparing enthalpy changes of the absorption,and then Mulliken population changes were analyzed.The results show that the absorption of tar model compound radical and CaO is an exothermic reaction.Formation of C—O—Ca is more easily than that of C—Ca—O and formation of Caromatic—Caromatic—Ca—O is more easily than that of Caromatic—C(O)—Ca—O.The C—C bond Mulliken populations in tar model compound radicals are reduced by 11.9%,10.5% and 15.5% in the case of a hydrogen atom removed,and those are 15.7%,14.3% and 16.3% in the case of two hydrogen atoms removed through the absorption of CaO.Catalytic ability of CaO acting on the tar model compound is in an order of phenol>benzene>toluene.
文摘In order to investigate whether zinc atom is compatible with 1, 3, 3-trinitroazetidine(TNAZ) structure, TNAZ+Zn and 2 TNAZ+Zn composite systems have been considered within the constraints of density functional theory at the level of B3 LYP/6-31++G(d,p) and ωB97 X-D/6-31++G(D,P). In the case of TNAZ+Zn composite the both level of calculations resulted that one of the C-NO2 bonds of TNAZ undergoes bond cleavage. However, as the zinc content decreases by increasing the TNAZ content, C-NO2 bond elongation considerably decreases, although it is still longer than the similar bonds in 2 TNAZ+Zn composite in which zinc, by weight, is 7.14%. In all the cases the zinc atom acquires positive charge. The results indicate that the interfrontier molecular orbital energy gaps(HOMO-LUMO energy difference) of the composites decrease as the zinc content decreases.
基金The Ministry of Science and Higher Education of the Russian Federation(Agreement with Zelinsky Institute of Organic Chemistry RAS No 075-15-2020-803).
文摘The work addresses to the study of the molecular and crystal structure and properties of a new energyintensive compound 3,6-bis(2,2,2-trinitroethylnitramino)-1,2,4,5-tetrazine(NBTAT),first obtained by the authors in 2020.NBTAT compound crystallizes in the monoclinic system,space group P2(1)/n,density at room temperature 1.939 g/cm^(3).The energies of crystal packing and pairwise intermolecular interactions in NBTAT and its unnitrated analogue BTAT were calculated,and their comparative analysis was carried out.The enthalpy of formation of NBTAT molecules was calculated by quantum-chemical methods using Gaussian 09,and the enthalpy of formation of NBTAT in the solid phase(618 kJ/mol)was estimated.The energy capabilities of NBTAT as an oxidizer of solid composite propellants are estimated.It is shown that in metal-free compositions NBTAT is significantly superior to ammonium perchlorate(AP),dinitramide ammonium salt(ADN),HMX,BTAT at all stages of rocket systems,and is comparable to the superdense CL-20 yielding to the latter at the lower stages and slightly winning at the upper stages.
