Ben M. Benjamin

Thermal cleavage of chemical bonds in selected coal-related structures☆

Abstract Solvent-refined coal is produced in processes in which coal is heated with hydrogen-donor solvents. From it, oil, asphaltene, and preasphaltene fractions can be separated. The sizes of the molecules in these fractions are smaller than the sizes of those in the starting coal; the smaller sizes result from bond-breaking reactions. We have investigated the bond-breaking processes by determining what kinds of bonds rupture when each of a large number of carefully selected model compounds was subjected to the conditions of asphaltene formation. Both tetralin and vitrinite from Illinois No. 6 coal were used as hydrogen donors. The products of chemical breakdown of the model compounds are presented in several Tables. Relative rates of cleavage of some selected compounds were also determined. The information obtained is discussed in relation to structural features of coal.

New chemical structural features of coal

Abstract An adaptation of the transalkylation reaction provides a means for cleaving alkyl substituants off of the aromatic portions of coal as well as extracting aliphatic connecting groups from between aromatic clusters. Using reasonably low concentrations of acid catalysts, the groups are transferred to an acceptor without modification or rearrangement and identified by means of convenient laboratory procedures. The catalyst in this procedure is trifluoromethanesulphonic acid and toluene is the acceptor. The reaction was performed on several samples of coal and gave toluene solutions containing a large number of derivatives. Results are reported for Wyodak coal. A list of substituents and several new connecting groups is recorded.

Deno oxidation. Isolation of high-molecular-weight aliphatic material from coals and further model compound studies/

Abstract Long-chain aliphatic materials present in coals are not completely oxidized using the procedure described by Deno ( Fuel 1978, 57 , 455). They are adsorbed on the filter cake during the work-up procedure and can be isolated by extracting the filter cake. The amounts present are similar to those observed by Hayatsu et al . (Fuel in press). Also-phenol is not completely oxidized under these conditions, but gives products with m/e as high as 310. Products from the oxidation of phenol include ethane and propane tricarboxylic acids and benzene tri- and tetracarboxylic acids.

New chemical structural features of coal. A comparison of several coals

Abstract Structural features of several coals of different ranks are compared using an adaptation of the transalkylation reaction. In the present application of this method, trifluoromethanesulphonic acid is used as catalyst and toluene is used in excess as acceptor and solvent. The process can be visualized as a disproportionation reaction in which intermolecular alkyl transfers occur. Under the influence of the acid catalyst, aryl-alkyl bonds in coal are cleaved and alkyl-aryl bonds are formed with the excess toluene solvent. Thus, a large number of substituted toluene derivatives are formed by transfer of groups from coal. Concentrations of ≈ 20 substituent groups and connecting groups are estimated and compared for a range of coals and numerous other compounds are present in small amounts. These compounds are tabulated for two coals and the possible significance and origin of some of them are discussed. The mechanism of the transalkylation reaction as it applies to coal and the reactions of a limited number of relevant model systems are also discussed.

New chemical structural features of coal. The structure of coal products

Abstract The object of this paper is to demonstrate the usefulness of the transalkylation reaction for determining chemical structural features of products derived from coal. For example, the method is applied to derivatized coals, coals modified by thermolysis, and materials physically or chemically separated from coals. Data are presented for the pyridine soluble and insoluble parts of two coals, an O-methylated coal, a Birch reduced coal, a solvent refined coal, and a coke. Similarities and differences in chemical make-up of these materials are discussed.