Search

[Display omitted] • Established the relationship between molecular properties and electrode performance. • Biomass is used to realize the value of energy storage. • The carbon source unsaturation is obtained from the double bond equivalent diagram. Porous carbon materials have been considered a kind of promising materials for supercapacitors due to high specific surface area and excellent electronic conductivity. Soluble portions (SPs) acquired from thermal dissolution of carbon-based raw materials have been used as the carbon source for hierarchical porous carbons (HPC). In this work, mixtures of rice straw and coal at different mass ratios were selected as the raw materials for co-thermal dissolution to obtain SP X. The variation of soluble proportions and subsequent impacts on the electrochemical properties of HPC X were investigated. During thermal dissolution, the addition of rice straw increased the content of nitrogen-containing compounds in SP X. Therefore, the specific capacitance of HPC 1/4 is 355 F/g. The specific capacitance of activated carbon material without rice straw is only 299 F/g. The relationship between the molecular characteristics of carbon source and the performance of supercapacitors has been determined. In addition to oxygen-containing compounds, the presence of nitrogen-containing compounds can also lead to a higher electrochemical property for porous carbon materials. [ABSTRACT FROM AUTHOR]

Direct liquefaction of Chinese Hami sub-bituminous coal was conducted with binary mixtures of hydrogen donor solvent tetralin (THN) and non-donor 1-methylnaphthalene (1-MN) or naphthalene (Nap.). Effects of solvent composition, temperature, atmosphere, and catalyst FeS 2 on product distribution and hydrogen consumption were investigated at solvent/coal mass ratio of 2. The results show that oil yield increases from 47.70% to 59.95% with 1-MN/THN ratio changing from 2:1 to 1:2. Hydrogen donating ability of binary solvents increases with the rising ratio of THN. H 2 contributes noticeably positive effect on coal conversion in the case of liquefaction with insufficient hydrogen donor solvent. Oil yield obtained during direct coal liquefaction (DCL) with Nap./THN is 58.32%, which is 10.62% higher than that with 1-MN/THN at same solvent ratio of 2:1. This is owing to demethylation effect of 1-MN under liquefaction condition. 1-MN demethylation is induced by active hydrogen and coal radicals, and could consume noticeable hydrogen during DCL. This indicates that the amount of alkylarenes included in liquefaction mixed solvents should be limited, or sufficient hydrogen donor solvent is required to achieve high coal conversion. [ABSTRACT FROM AUTHOR]

• Enrichment characteristics are probed from the molecular structure. • Aliphatic hydrocarbons were selectively enriched by polydimethylsiloxane coating. • Oxygenated aromatic species with multiple and/or long side chains were enriched. Due to the low concentration of minor compounds and the detection limit of instruments, numerous compounds in the thermal dissolution (TD) extract of coals cannot be detected. Therefore, it is necessary to introduce solid phase microextraction (SPME) for sampling before analysis, which can enrich compounds in mixtures with similar molecular structures and exclude interferences from other components. In this work, partial species in the TD extract of Zhaotong lignite were enriched by SPME with a polydimethylsiloxane (PDMS) coating. The enrichment characteristics of the coating on TD extract were examined by gas chromatography-mass spectrometry (GC–MS). Nitrogen-containing compounds and sulfur-containing compounds were removed from the enriched species, and the content of aliphatic hydrocarbons increased from 30.0% to 93.2% after enrichment. Oxygenated aromatic compounds with structures similar to the long-chain siloxane bonds of PDMS were also enriched. This study establishes a SPME method and provides a basis for the analysis of lignite and its derivatives. [ABSTRACT FROM AUTHOR]