Exploratory coprocessing research. Quarterly report Number 9, September 1--November 30, 1990

The objectives of this project are to: (1) study the scope of hydrothermal pretreatment of coal on subsequent conversion, (2) identify and study the chemical or physical causes of this effect, and (3) attempt to elucidate the chemistry responsible for any coal-resid synergisms. This project is divided into three tasks. This quarter the authors concentrated on Tasks 2 and 3 as described below. Task 2: chemistry of pretreatment. This Quarter they continued their investigation of the chemistry of pretreatment using an iron catalyst, (ferrous sulfate), both with and without aqueous pretreatment on Wyodak coal. The combination of iron and hydrothermal pretreatment gave the best results, as long as the pretreated coal was not dried prior to conversion. However, the combination of iron and pretreatment gave similar conversions as with pretreatment alone. Task 3: chemistry of synergy. To help provide a baseline for distinguishing between the benefits resulting from chemical and physical solvency factors, the authors decided to conduct some experiments in homogeneous systems, from which they can easily extract the impact due to chemical changes. They synthesized a series of benzyl aromatics and studied their cleavage in a mixture of anthracene and dihydroanthracene. Cleavage rates for the different substrates increase in the order diphenylmethane < benzylnaphthalene < benzylphenanthrene < benzylpyrene. The log of observed first-order rate constants correlate linearly with the exothermicity of H-addition to the aromatic bearing the benzyl group, and are in excellent agreement with previously modeled results. The experimental results further show the generality of induced bond cleavage, and buttress the view of the possible chemical basis of improvements resulting from increased aromaticity