Low-temperature hydropyrolysis of coal under pressure of H2-CH4 mixtures

Hydropyrolysis of a Beringen bituminous coal (VM, 32.8wt%) has been studied in a fixed bed reactor with different gas flows of H₂-CH₄ and H₂-N₂ mixtures. At 580 °C, various hydrogen partial pressures between 0 and 1 MPa were used with a total pressure of 1 and 4 MPa. Oil yield increased significantly with increasing hydrogen partial pressure. However, if the difference between partial and total pressure is too large, the oil yield is affected more by the total than the hydrogen partial pressure. Similar effects are observed for the yields of BTX, PCX and naphthalenes except that for the latter the total pressure does not have a significant effect. In the conditions investigated the methane is chemically inert. Thus it is possible to recycle the gas during coal hydropyrolysis with only a slight decrease of the yields.