CARBON-MONOXIDE PRETREATMENT OF SUBBITUMINOUS COALS

Thermal CO pretreatment of Wyodak subbituminous coals from the Clovis Point and Black Thunder mines in aqueous media at 300 degrees C produc es a water-insoluble product having a higher hydrogen content, lower o xygen content, higher volatility, and increased solubility in pyridine . Oxygen-rich, water-soluble organic acids are formed in the absence o f CO or at low CO pressures. However, at 800 psig of CO, the water-sol uble organic product is absent. Both coal hydrogenation and CO convers ion were examined in the presence of added OH-, CO(3)(2-)and HCO3-. CO conversion is related to formation of formate in the aqueous phase an d the generation of CO2 and H-2. Chemical, thermogravimetric, and opti cal microscopic data of the pretreated material indicate major modific ation of the coal structure during pretreatment. Liquefaction of the p retreated material at 400 degrees C in hydrogen/tetralin with or witho ut catalysts (Fe and Ni-Mo) indicates that pretreatment gives higher c onversion and, in most cases, higher oil yields and lower hydrogen con sumption than with the untreated coal.