Clean fuels and chemicals from coal with CO₂ capture for sustainable energy development

This lecture provides an overview of recent advances in the research and development on conversion of coal to clean fuels, chemicals and materials with CO2 capture. As one of the major energy sources in the world today, coal has an important role in sustainable energy development because the amount of known resources is much larger for coal (with demonstrated reserves over 250 times the current annual consumption) than that for natural gas (about 60 times) and that for petroleum (about 40 times). US, China, Australia and many other countries have large and wide-spread coal-mining operations and coal utilization plants in electric utilities plus some carbonization and gasification in industries related to iron and steel, hydrogen, ammonia and methanol synthesis. Shortage in resources magnified by rise in price for energy and increase in demand for liquid and gaseous fuels as well as hydrogen have stimulated major R&D efforts in coal gasification, Fischer-Tropsch synthesis, methanol and dimethylether synthesis, and direct coal liquefaction. The so-called coal-to-liquids (CTL) includes direct and indirect liquefaction, both have been explored intensively. The indirect CTL in SASOL and direct CTL in China have been in commercial operation. Recent advances in gasification and liquefaction will be reviewed. Coal structure is characterized by aromatic rings that are abundant in various coal-derived liquids from liquefaction, pyrolysis, carbonization, and certain gasification processes. New approaches by shape-selective catalysis has become promising for developing value-added chemicals and engineering materials from polycyclic aromatic hydrocarbons such as naphthalene, biphenyl, and phenanthrene. In contrast to previous coal utilization research till early 1990s, CO2 capture has become an important option for using coal without negative green-house gas (GHG) impacts to climate change. Some new approaches will be discussed for developing high-capacity sorbents for selective CO2 capture and separation.