Changes in Asphaltenes and Preasphaltenes with Reaction Conditions and Effects on Coal Structure

摘要

Asphaltene and preasphaltene data are presented to demonstrate the effect of temperature, pressure, and reducing gas composition on their hydrogen and phenolic content. The previous paper by Baltisberger showed how the hydrogen and phenolic content of the A and PA defined whether or not a coal derived product will be classified as such. The influence of processing parameters as discussed in this paper indicates that reduction in the number of phenolic functional groups and cracking are required to further convert asphaltene and preasphaltene material to distillates. That alcohol groups are present in aromatic bridging structures is indicated in the data in this report by the decreased MW of SR when processed with CO present since after hydrogenation an aliphatic bridge would cleave easier. The increased aliphatic hydrogen content in the asphaltene fraction when reacted with CO may also indicate that some alcohol groups were initially in the aromatic bridges. The presence of alcohol groups in long chain aliphatics is indicated because increased yields of long chain alkanes were observed when CO was present. The previous data have shown how operating conditions such as pressure and temperature affects the hydrogen content, phenolic content, and molecular weight range of asphaltene and preasphaltene fractions. The effects are reflected similarly in individual MW fractions of both A and PA material. The presence of alcohol groups in original coal (both lignites and bituminous coals) is strongly suggested. The preferential reaction of these alcohol groups with CO gas (but not H sub 2 ) to increase the hydrogen content of the asphaltenes, to reduce the overall MW distribution of coal, and to increase yields of alkanes indicates the beneficial effects of CO as a reductant of these functional groups which are present in both lignites and bituminous coals. 20 references, 8 figures. (ERA citation 09:032451)