Investigations into coal coprocessing and coal liquefaction

The conversion of coal to liquid suitable as feedstock to a petroleum refinery is dependent upon several process variables. These variables include temperature, pressure, coal rank, catalyst type, nature of the feed to the reactor, type of process, etc. Western Research Institute (WRI) has initiated a research program in the area of coal liquefaction to address the impact of some of these variables upon the yield and quality of the coal-derived liquid. The principal goal of this research is to improve the efficiency of the coal liquefaction process. Two different approaches are currently being investigated. These include the coprocessing of a heavy liquid, such as crude oil, and coal using a dispersed catalyst and the direct liquefaction of coal using a supported catalyst. Another important consideration in coal liquefaction is the utilization of hydrogen, including both externally- and internally-supplied hydrogen. Because the incorporation of externally-supplied hydrogen during conversion of this very aromatic fossil fuel to, for example, transportation fuels is very expensive, improved utilization of internally-supplied hydrogen can lead to reducing processing costs. The objectives of this investigation, which is Task 3.3.4, Coal Coprocessing, of the 1991--1992 Annual Research Plan, are: (1) to evaluate coal/oil pretreatment conditions that are expected to improve the liquid yield through more efficient dispersion of an oil-soluble, iron-based catalyst, (2) to characterize the coke deposits on novel, supported catalysts after coal liquefaction experiments and to correlate the carbon skeletal structure parameters of the coke deposit with catalyst performance as measured by coal liquefaction product yield, and (3) to determine the modes of hydrogen utilization during coal liquefaction and coprocessing. Experimental results are discussed in this report.