Prospects for Catalysts in Coal Liquefaction

In spite of extensive efforts to improve coal liquefaction, so far, coal-derived oils cannot compete with petroleum. The cost of coal liquefaction must be lowered to produce petroleum substitutes at a reasonable price. 

The cost of coal liquefaction is most sensitive to the capital costs of the facility. Hence, higher yields of products at the same facility or fewer and/or 

the authors propose that an improved coal liquefaction process may be one in which complete conversion of coal with minimal formation of residue should be the primary goal, even if hydrocarbon gas yields increase. These hydrocarbon gases are easily converted to recover the hydrogen they consume. 

A liquid/solid separation step is usually required before the catalytic reaction with nondisposable catalysts. This is an expensive step. To remove it, the catalyst must be compatible with the contaminating solids. Ebulating beds can partially satisfy this condition, but the rate of catalyst replacement becomes large if the deactivation is severe. 

Solid coal is transported as a slurry. Hence, the solvent is necessary in any case. However, reduction of its amount is very critical to improving the productivity of the facility at reduced cost. The solvent requirement, especially after dissolution of coal, can be reduced by improved catalysts. 

---