INSIGHTS INTO COAL SOLUBILIZATION DURING COAL-BITUMEN COPROCESSING ASMONITORED BY C-13 C-12 RATIOS

The optimization of coal-bitumen coprocessing would be facilitated by a quantitative measure of the amount of coal incorporated into all the individual product fractions. Intrinsic C-13/C12 ratios of coal and b itumen are sufficiently different that they can be used as tracers to this end by applying isotopic mass balance. However, thermal treatment may cause isotopic fractionation in bitumen and coal complicating the application of a simple mass balance. To minimize this effect, mild e xperimental conditions were chosen for this study. Also, isotopic frac tionations induced in bitumen by processing at these conditions were d etermined and used to correct mass balance calculations for the concen tration of dissolved coal in product. The effect on coal solubilizatio n of coal loading, catalysts and presence of coal ash was investigated . Also the fate of coal dissolved in distillate from coprocessing was traced through further secondary hydrotreatment. (a) Concentration of coal in the initial charge influenced the proportion of coal and bitum en in the product fractions. The yield of distillate from both coal an d bitumen, and the yield of pentane soluble product from the coal were relatively independent of the size of the initial coal charge; howeve r, distinct relationships were observed among the other fractions. (b) Different elements doped to iron oxide affected coal and bitumen tran sformation differently. Effective iron based catalysts for coprocessin g that left minimal toluene insoluble residue from coal were Fe2O3, Fe 2O3/TiO2 and a sludge from nickel refining. (c) Coal ash was shown to improve coal solubilization. (d) Dissolved coal was preferentially con centrated into light oil after secondary hydrotreatment of coprocessed distillates.