Coal/Petroleum Residuum Interactions during Coprocessing under Noncatalytic, Low Solvent/Coal Ratio Conditions

Abstract

Coprocessing reactions were carried out using five coals and three petroleum residua at 350, 400, and 450 °C with N2 and H2. No catalyst was used. The interactions between the coal and the petroleum residua were investigated in terms of following the conversions and yields of THF-insolubles. The influence of temperature, time, petroleum residua, and coal characteristics was examined. Conversions at or below 400 °C are primarily determined by the nature of the coal. The characteristics of the residuum have little influence on the coal conversions. The residuum behaves like a liquid medium for the coal fragments at this temperature regime and does not have properties of a hydrogen donor or hydrogen shuttler. The maximum coal conversion is ≈40 wt %, comparable to the conversions obtained in pyrene under the given conditions. At temperatures >400 °C retrogressive reactions are observed, indicated by low or even overall negative conversions (−20 wt %). The retrogressive reactions are a result of the interactions between the coal and petroleum residuum fragments and are influenced by the properties of the coal as well as the petroleum residuum. Both the coal and the residuum must be undergoing thermal decomposition for the retrogressive reactions to occur. Residua that have a higher degree of polycondensation (Har/Car ≤ 0.4) may be inferior coprocessing solvents at temperatures >400 °C. Similarly, noncaking coals proved to be less desirable than caking coals.

Relationship of Coal Characteristics Determined by Pyrolysis/Gas Chromatography/Mass Spectrometry and Nuclear Magnetic Resonance to Liquefaction Reactivity and Product Composition

“…Comparison of Coal Compositional or Structural Parameters and Reactivity in Liquefaction. The present results are consistent with previous noncatalytic experiments that showed an inverse relationship between the oxygen content (or atomic O/C ratio) of coals and liquefaction conversions 39 and the effect of coal fluidity on conversion in model compounds or petroleum residua. , An inverse relationship exists among these coals for reactions at 425 °C, similar to earlier results based on reactions at 350, 360, and 400 °C. The highest conversions in our present work were obtained with DECS-12, which has the highest free swelling index among these coals, and with DECS-6.…”

Laboratory-Scale Coking of Coal−Petroleum Mixtures in Sealed Reactors

“…It allows for the upgrading of coal to produce quality liquid products by utilizing a petroleum stream as an inexpensive hydrogen-donating solvent that could be used in once-through operation, eliminating the need for solvent recycling. The status of co-processing through the late 1970s has been summarized in the useful review by Moschodepis et al Co-processing has remained a subject of active research, with investigations of, e.g., hydrogen transfer or donation, − effects of coal concentration in the system, ,,− product distributions, ,,,,, and product quality, ,,, including the effects of metals or heteroatoms ,, and the effects of reaction conditions. ,, Our work differs from the better-known co-processing in several aspects:…”

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

“…Co-processing is another way to convert the coal into clean liquid fuel. Co-processing increases the distillate yield by suppressing the coke formation and enhancing the removal of heavy metals. , The usage of different heavy oils and the properties of heavy oils used in the co-processing of coal, − different coal usage and coal concentration in the blend, , catalyst type used, − and reducing gaseous atmosphere , have been reported. Heavy oil in the co-processing of coal is considered to act as a solvent to provide liquid medium for the thermally formed fragments of coal.…”