Relationship between solids formation, residuum conversion, liquid yields and losses during athabasca bitumen processing in the presence of a variety of chemicals

Abstract

Conditions were chosen for the batch processing of Athabasca bitumen such that approximately 8% of the feed was converted to solids under an atmosphere of nitrogen. When hydrogen or tetralin was used, the amount of solids formed was cut in half. The combination of hydrogen and tetralin decreased the amount of solids formed by one‐half again. These conditions were used to study radical trapping reactions and hydrogen transfer under a variety of conditions using solids formation as a measure of reaction. None of the reagents used decreased solids formation significantly, and many increased the retrograde reaction. Correlations between solids formation (2–25% of feed) and yields and conversions showed that CCR conversion and sulfur conversion were not correlated with solids formation but nitrogen and vanadium conversions were. Most significant was the finding that losses (yields of gases) were constant for the 29 runs, at constant residuum conversion. Gases must be formed as a result of the initial thermally induced carbon‐to‐carbon bond breaking step in order for the yield to be independent of solids formation. Distillate yields decreased as solids formation increased.

Role of Chain Reactions and Olefin Formation in Cracking, Hydroconversion, and Coking of Petroleum and Bitumen Fractions

“…Other experiments lend support to the latter interpretation. Sanford and Xu compared cracking of Athabasca in the presence of methane to ethylene, at the same temperature of 400 °C and total pressure of 8.4 MPa for 240 min. Reaction in the presence of methane gave 7.5 wt % of toluene-insoluble coke, while reaction in the presence of ethylene gave 12.9 wt % coke.…”

Hydrogen Transfer and Coking Propensity of Petroleum Residues under Thermal Processing

“…For inhibiting coking of Asp, if the Re fraction is called the primary “fighting” agent, the Ar fraction is then the secondary. Sanford and Xu showed that hydrogen donor agentstetralin and hydrogen gassuppressed coke formation, whereas a hydrogen accepting agentethylene gaspromoted coke formation. These agents may thus supplement or deplete donatable hydrogens of Ar and Re, thus influencing the coking rates of Asp in the center.…”

“…Coking propensity has been vastly investigated under residue thermal processing conditions. − Wiehe found that coke induction period is a common feature of residue thermal conversion kinetics. He reported that maltene and asphaltene fraction (Asp) had 90 and 0 min induction periods, respectively, whereas their parent residue with Asp content of 25 wt % had a 45 min induction time.…”

“…Considering a reduction in coke yield as an obvious indication of hydrogen transfer, Sanford and Xu used coke yields resulted from reaction under a variety of conditions as the main indicator of hydrogen transfer. Sanford and Xu investigated the influence of hydrogen donor/acceptor additives on coke formation of Athabasca bitumen under thermal processing.…”

“…Considering a reduction in coke yield as an obvious indication of hydrogen transfer, Sanford and Xu used coke yields resulted from reaction under a variety of conditions as the main indicator of hydrogen transfer. Sanford and Xu investigated the influence of hydrogen donor/acceptor additives on coke formation of Athabasca bitumen under thermal processing. When hydrogen gas or tetralin (good hydrogen donors) were used, coke formation was cut in half (i.e., 4.2 wt %), and the combination of hydrogen gas and tetralin decreased coke formation by one-half again (i.e., 2.0 wt %).…”