Coal solubilized

Figure 10 shows the sequence of chemical and physical effects leading to coal solubilization under mild conditions. The first step in the conversion involves catalyst-coal contacting a slow rate of contacting may limit the effective reactivity of the catalytic medium. The nature of the... 

The extent of depolymerization of these coals (Table II) ranges from 25.3 to 88.7 percent. This defines the amount of maf coal solubilized. With this particular array of coals, the coal solubilized bears almost an inverse relationship to the combined phenol. This appears to be dictated by chance nevertheless, the coals to the right side of Table II take up more phenol in relation to the amount solubilized than those to the... 

The obvious danger of structural studies involving coal solubilization followed by the investigation of the reaction products is the possibility of transformation of the primary products by further reaction. However, our results (1,2) indicate that at short contact times the principal reactions involve only thermal cleavage of the weaker bonds, and therefore the intrinsic elements of the coal structure are preserved without modification. 

The Role of Ether-Linkages in Solubilization of Low-Rank Carboniferous Coals by H-Donors... 

Formation of asphaltenes during solubilization of low-rank bituminous coals has been attributed to cleavage of open ether-bridges (6). But while the presence of such configurations in high- and medium-rank bituminous coals is well established (7), their existence in less mature coals remains to be demonstrated. From reactions of low-rank bituminous coals with sodium in liquid ammonia or potassium in tetrahydrofuran, it has, in fact, been concluded that open ether-bonds are absent (8) or only present in negligible concentrations (9). 

Non-Destructive Solubilization of Low-Rank Bituminous Coal (by non-reductive alkylation)... 

Present methods for solubilizing coal (including reductive alkylation in tetrahydrofuran (15) or liquid ammonia (8)) entail cleavage of oxygen ethers, scission of C-C bonds in certain polyaryl-substituted ethylenes and, in the case of reactions in tetrahydrofuran, extensive elimination of hetero-atoms (16). 

We therefore draw attention to a novel technique which allows solubilization of coal without rupture of covalent bonds. This utilizes the fact that the acidity of low-rank coals, which is largely due to their high -OH contents, can be enhanced by proper choice of a medium. 

Mochida and co-workers have also shown that the degree of solubilization of coals in polyaromatic solvents relates directly to their fluidity (18). We did not obtain fluidity measurements directly on this series of coals but data developed by Honda (19) indicate that a maximum in fluidity occurs at 85% Cmaf (see Figure 11). This is in the same region of carbon content in which we observed a maximum in conversion at short time (see Figure 6). 

If the initial reactions of coal are purely thermal, one might expect that the H-donor level will be of minor importance if times are kept short. In fact, all coals contain a certain portion of material that is extractable by pyridine. On heating coals to liquefaction temperatures, some additional material also becomes soluble in even non-donor solvents. Thus, there is a portion of all coals which can be solubilized with little dependence on the nature of the solvent. 

In addition to knowing the total MTC solubility, it was important to determine the amount of methanol or other solvent retained by the MTC. This quantity, the incorporation ratio (R, gm incorporated organic material/gm coal-derived organic material), was determined by a carbon balance on the reaction. By assuming that any solvent retained in the dried MTC is pyridine-soluble, and subtracting it from the total dissolved material, the minimum solubility of the coal-derived material may be calculated. This quantity, the corrected solubility, is an indicator of the true solubilizing effect on the coal by the particular run conditions. ... 

As shown in Figure 3, solubilization roughly conforms to first-order kinetics, where rate = k[unconverted coal]. Rate constants of 3 x 10 and 1 x 10 min l are found for 250° and 275°C respectively, with nearly total conversion in less than 30 minutes at the higher temperature. Although negligible reaction takes place with heatup to 250°C (so-called "zero time), considerable reaction occurs in the few minutes of heatup between 250° and 275°C. During this period, solubility rises 20%, incorporation approaches its maximum extent, and the H/C ratio drops to 0.75. 

Figure 10. Sequence of reactions leading to solubilization of coal under mild...

Shinn, J. H. Vermeulen, T. "Scanning Electron Microscopy Study of the Solubilization of Coal Under Mild Conditions". Paper submitted for presentation at Scanning Electron Microscopy Symposium, Washington, D.C., April 1979. 

TABLE I. Structural Characteristics of Coal Fractions Separated from Solubilized... 

The introduction of atomic absorption spectroscopy has resulted in major advances in the rapid analysis of many elements. Initially, atomic absorption was applied only to aqueous systems or to materials that could be readily solubilized. There are methods to analyze major elements in such complex materials as silicates and vitreous siliceous coal ashes (1-5). More recently, lithium metaborate has been reported to be a good fluxing agent (6) and has also been used in conjunction with atomic absorption analysis in silicate analysis (7). This paper describes a lithium tetraborate-atomic absorption analytical technique which is being used to analyze coal ash. 

Maurice Mitchell, Jr. The answer to Dr. Wender s question, in my opinion, is that where solubility is an equilibrium phenomenon, Heredy s work shows a mechanism for solubilizing coal. Thus, although the differences in... 

Solubilize coal and conven the soluble product to liquid or gaseous fuels, and... 

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