Co-processing of Turkish High-Sulfur Coals and Their Blends with a Petroleum Asphalt. Part 1: In the Absence of a Catalyst

Abstract

In this study, two Turkish coals, namely, Cayirhan (CC) and Kangal (KC), characterized by high levels of ash and sulfur, were co-liquefied with petroleum asphalt (Asp) at 400, 425, and 450 °C. The liquefaction/prolysis of coals and petroleum asphalt under nitrogen and hydrogen atmospheres was also performed at 400 °C. The distribution of the main product fractions (total conversion, oil, preasphaltene + asphaltene, and gas) obtained from liquefaction/pyrolysis and co-liquefaction and the detailed chemical composition analyses of liquid products using gas chromatography−mass spectrometry (GC−MS) are given. The effect of liquefaction/pyrolysis conditions on the product quality was assessed. These coals showed quite different responses to similar liquefaction conditions because of the structural differences in the main carbon framework and also the differences in mineral matter composition. In all co-liquefaction reactions, the oil yields decreased significantly (10−18%) at 450 °C compared to those at 400 °C, possibly because of some retrogressive reactions. The amount of open-chain paraffins (alkanes + alkenes + alkynes) in the oils obtained from co-liquefactions was observed higher under the hydrogen atmosphere than under the nitrogen atmosphere. The reverse was true for the contents of alkylbenzenes. The amount of open-chain paraffins in oils increased, while alkylbenzenes and phenols decreased when the asphalt ratio was increased in the blend. In all co-liquefaction reactions, the openchain paraffins decreased, while the amounts of naphthalene, alkylnaphthalenes, and other condensed arenes increased at 450 °C liquefaction results compared to 400 °C liquefaction results.