Solubility study of hydrogen in direct coal liquefaction solvent based on quantitative structure–property relationships model

Direct coal liquefaction(DCL)is an important and effective method of converting coal into high-valueadded chemicals and fuel oil.In DCL,heating the direct coal liquefaction solvent(DCLS)from low to high temperature and pre-hydrogenation of the DCLS are critical steps.Therefore,studying the dissolution of hydrogen in DCLS under liquefaction conditions gains importance.However,it is difficult to precisely determine hydrogen solubility only by experiments,especially under the actual DCL conditions.To address this issue,we developed a prediction model of hydrogen solubility in a single solvent based on the machine-learning quantitative structure–property relationship(ML-QSPR)methods.The results showed that the squared correlation coefficient R^(2)=0.92 and root mean square error RMSE=0.095,indicating the model’s good statistical performance.The external validation of the model also reveals excellent accuracy and predictive ability.Molecular polarization(a)is the main factor affecting the dissolution of hydrogen in DCLS.The hydrogen solubility in acyclic alkanes increases with increasing carbon number.Whereas in polycyclic aromatics,it decreases with increasing ring number,and in hydrogenated aromatics,it increases with hydrogenation degree.This work provides a new reference for the selection and proportioning of DCLS,i.e.,a solvent with higher hydrogen solubility can be added to provide active hydrogen for the reaction and thus reduce the hydrogen pressure.Besides,it brings important insight into the theoretical significance and practical value of the DCL.

Mechanism of dibenzofuran hydrodeoxygenation on the Ni(1 1 1)surface

The low-temperature coal tar contains a considerable number of oxygen-containing compounds,which results in poor quality.The catalytic hydrodeoxygenation of oxygen-containing compound to an added-value chemical compound is one of the most efficient methods to upgrade coal tar.In this study,density functional theory calculations are employed to assess and analyze in detail the hydrodeoxygenation of dibenzofuran,as a model compound of coal tar,on the Ni(111)surface.The obtained results indicate that dibenzofuran can be firstly hydrogenated to tetra hy d rod i be nzofura n and hexahydfodibenzofufan.The five-membered-ring opening reaction of tetrahydrodibenzofuran is more straightforward than that of hexahydrodibenzofuran(Ea=0.71 eV vs.1.66 eV).Then,both pathways generate an intermediate 2-cyclohexylphenoxy compound.One part of 2-cyclohexylphenoxy is hydrogenated to 2-cyclohexylphenol and consecutively hydrogenated to cyclohexylcyclohexanol,and another part is directly hydrogenated to cyclohexylcyclohexanone.The hydrogenated intermediates of2-cyclohexylphenol have higher deoxygenation barriers than 2-cyclohexylphenol and cyclohexylcy clohexanol.During the hydrogenation process of cyclohexylcyclohexanone to cyclohexylcyclohexanol,the intermediate 26,formed by adding H to O atom of cyclohexylcyclohexanone,exhibits the lowest deoxygenation barrier of 1.08 eV.High hydrogen coverage may promote the hydrogenation of tetrahydrodibenzofuran,hexahydrodibenzofuran,and intermediate 26 to generate dodecahydrodibenzofuran and cyclohexylcyclohexanol.This dibenzofuran hydrodeoxygenation reaction mechanism corroborates well with previous experimental results and provides a theoretical basis for further optimization of the design of nickel-based catalysts.

Analysis of mechanism of Buzhong Yiqi Decoction in treating senile functional constipation via network pharmacology

Objective:To explore the molecular mechanism of buzhong yiqi decoction in the treatment of senile functional constipation based on network pharmacology.Methods:Chemical compositions and selected targets related to the eight traditional Chinese medicine herbs were searched through the Traditional Chinese Medicine Systems Pharmacology Database and Analysis Platform(TCMSP).Through GeneCards database and OMIM database,disease targets of senile functional constipation were searched.R language was used to screen the common targets between drugs and disease,and then the interaction network diagram of the targets was constructed by String.Cytoscape3.7.0 was applied to construct the traditional Chinese medicines-chemical compositions-disease targets network.GO enrichment analysis and KEGG enrichment analysis of the targets were based on DAVID.Results:Five main chemical compositions including quercetin,kaempferol,nobiletin,naringenin and formononetin were screened,and five key targets including PTGS2,ESR1,AR,NOS2 and PPARG were identified.622 GO functional entries and 125 pathways were yielded by gene enrichment analysis.Conclusion:Buzhong yiqi decoction may play the role of anti-inflammatory and anti-oxidation through multi-component,multi-target and multi-channel,so as to improve senile functional constipation.

Tungsten doping La_(0.6)Ca_(0.4)Fe_(0.8)Ni_(0.2)O_(3-δ)as electrode for highly efficient and stable symmetric solid oxide cells

Perovskite oxide La_(0.6)Ca_(0.4)Fe_(0.8)Ni_(0.2)O_(3-δ)(LCFN)has been used in symmetric solid oxide cells(SSOCs)to obtain good electrochemical performance in both fuel cells(SOFCs)and electrolysis cells(SOECs)modes.However,its structural stability still faces challenges and the electrocatalytic activity also needs to be further improved.Herein,tungsten-doped La_(0.6)Ca_(0.4)Fe_(0.7)Ni_(0.2)W_(0.1)0_(3-δ)(LCFNW)perovskite oxide material was synthesized which exhibits good structural stability under H_(2)and superior electrochemical performance as an electrode for SSOCs.In SOFCs mode,the cell achieved the maximum power density of 0.58 W·cm^(-2)with wet H_(2)as fuel at 850℃.In SOECs mode,the current density can reach 1.81 A·cm^(-2)for pure CO_(2)electrolysis at 2 V.Moreover,the SSOCs exhibits outstanding long-term stability in both SOFCs and SOECs modes,proving that doping W in perovskite oxide is an effective strategy to enhance the catalytic activity and stability of the electrode.The LCFNW material developed in this work shows promising prospect as an electrode candidate for SSOCs.

Regulation of radicals by hydrogen-donor solvent in direct coal liquefaction

Radicals are important intermediates in direct coal liquefaction.Certain radicals can cause the cleavage of chemical bonds.At high temperatures,radical fragments can be produced by the splitting of large organic molecules,which can break strong chemical bonds through the induction pyrolysis of radicals.The reaction between the formation and annihilation of coal radical fragments and the effect of hydrogen-donor solvents on the radical fragments are discussed in lignite hydrogenolysis.Using the hydroxyl and ether bonds as indicators,the effects of different radicals on the cleavage of chemical bond were investigated employing density functional theory calculations and lignite hydrogenolysis experiments.Results showed that the adjustment of the coal radical fragments could be made by the addition of hydrogendonor solvents.Results showed that the transition from coal radical fragment to H radical leads to the variation of product distribution.The synergistic mechanism of hydrogen supply and hydrogenolysis of hydrogen-donor solvent was proposed.