New Insights into the Primary Reaction Products of Naomaohu Coal via Breaking Weak Bonds with Supercritical Ethanolysis

Abstract

Coal is an important energy source in the world, and its chemical structure is the basis of its application, especially for its pyrolysis and liquefaction. Supercritical ethanolysis is a type of chemical extraction that can effectively depolymerize some weak bonds in organic matter. In this work, new insights into the primary products of Naomaohu coal were studied with supercritical ethanolysis. The non-covalent and weak covalent bonds (such as ether and ester bonds) in the coal were broken to yield small molecular compounds (SMCs) with a conversion of 70.3% (dry and ash-free basis) at 370 °C. SMCs, including esters, alcohols, aldehydes, ethers, ketones, hydrocarbons (aromatic and aliphatic hydrocarbons), acids, phenols, and heteroatom compounds, were identified quantitively through gas chromatography/mass spectrometry. Fourier transform infrared spectroscopy and 13C nuclear magnetic resonance were used to characterize the structure of the coal and its ethanolysis residues. The structure characteristic of the coal was deduced through analyzing the SMCs and residues. Interestingly, the SMCs can reflect the primary reaction products of the coal during its pyrolysis or liquefaction.

Pyrolysis Kinetic Analysis of Sequential Extract Residues from Hefeng Subbituminous Coal Based on the Coats-Redfern Method

“…Peak 2, appearing at about 210 °C, might be related to the breakage of weak covalent bonds, such as >C al −O<, >C al −N<, and >C al −S−. 22 The weak covalent bonds presented a smaller peak area proportion, demonstrating that the number of organic compounds containing this type of bonds is smaller. The assignment of peak 3 around 450 °C, which is caused by the breakage of stronger bonds, such as >C al −C al < and >C al −S−.…”

“…Peak 1 occurs at about 70 °C, which could be related to the evaporation of water and small molecular gases. Peak 2, appearing at about 210 °C, might be related to the breakage of weak covalent bonds, such as >C al –O<, >C al –N<, and >C al –S– . The weak covalent bonds presented a smaller peak area proportion, demonstrating that the number of organic compounds containing this type of bonds is smaller.…”

Effect of MgO Promoter on the Structure, Performance and Carbon Deposition of Ni‐Al2O3 Catalyst for CO Methanation Based‐on Slurry‐bed Reactor

“…Four peaks were fitted using Peak-fit software. [32,33] The details of each peak were listed in Table 4. Peak 1 occurrence between 50-110 °C, where the weight loss in this temperature…”

Insights into the Relationship between the Microstructure and the Catalytic Behavior of Fe2(MoO4)3 during the Ethanolysis of Naomaohu Coal

“…Many studies were carried out on the ethanolysis of Naomaohu Coal. Liang et al conducted ethanolysis experiments on Naomaohu coal at different temperatures and analyzed the alcoholysis products [ 20 ]. Hu et al conducted ethanolysis experiments on NaoMaoHu coal, analyzed and characterized the alcoholysis products and residues, and deduced the reaction mechanism of ethanolysis [ 21 ].…”