Coal structure evolution and its fuel, raw material and functional material properties development

The resource endowment of “poor oil, less gas, and relatively rich coal” determines that China must adhere to the road of clean and efficient coal utilization. Coal is an organic rock rich in carbon, hydrogen, oxygen and other elements. It is the main fuel for heating and power generation, and an important raw material in metallurgy, chemical industry, and building materials. In this paper, a total of 16 coal samples with different metamorphic degrees were systematically collected. Combined with experimental and molecular simulation methods such as microscopic observation, infrared spectroscopy, nuclear magnetic resonance, gas adsorption, etc.,the differences in microscopic components, chemical components, molecular structures and porous structures were deconstructed. Then the geological influences on material structure differences is discussed to support the diverse development of fuels, raw material, and material properties. Medium and low rank coals are relatively hydrogen-rich, have good lipid fluorescence, and have important properties for the conversion and utilization of fuels and raw materials. Coalification is a process to continuously accumulate carbon, with the coal structure being gradually dense and oriented, and the properties of raw materials and material being strengthened. The swamp environment andpeatification determine the initial coal maceral compositions, which is comprehensively affected by climatic conditions, water properties, vegetation types and terrigenous debris. Coalification controls the evolution of coal chemical composition, molecular structure and porous structure. The vitrinite reflectances are about 0.65%,1.30% and 3.50% showing a step-like jump. Realizing the effective development of multiple properties, the pyrolysis reaction can obtain oil and gas components and tar products in coal, the combined force solution helps to realize the preparation and utilization of multi-dimensional carbon structures, and the understanding of the heterogeneity of porous media at the meter-centimeter-nanometer scale is helpful for material property development. On this basis, a full understanding on the interaction between the two components of “maceral-chemical” and the two structures of “molecular-porous” in the multiphase state of solid, liquid and gas molecules can help to realize coal-based multi-component clean energy and coal-based materials collaborative transformation and development. The continuous research and breakthrough in the above-mentioned scientific and technological issues will provide an assistance for China's energy structure adjustment and the implementation of the “dual carbon” strategy.