Upgrading Synthoil

The so-called cobalt molybdate catalyst has been used much in the petroleum industry for hydrotreating and hydrodesulfurization. More recently, these catalysts have been employed in coal liquefaction and synthoil upgrading. The latter probably accounts for the recent rash of publications on this very interesting catalyst system. Indeed, of the papers surveyed for this review, the majority have been published in the past 5 years with no letup in sight. 

Primary coal liquefaction products from three processes— solvent-refined coal, Synthoil, and H-Coal—were hydrotreated. Upgrading was measured in terms of the decrease in heptane and benzene insolubles, the decrease in sulfur, nitrogen, and oxygen, and the increase in hydrogen content. Hydrotreating substantially eliminated benzene insolubles and sulfur. An 85% conversion of heptane insolubles and an 80% conversion of nitrogen was obtained. Catalyst stability was affected by metals and particulates in the feedstocks. 

This chapter reports results of applying a catalytic hydrorefining process to four coal liquids solvent-refined coal (SRC) process filter feed, SRC extract product, Synthoil, and H-Coal process hydroclone underflow. The achieved upgrading is evaluated in terms of reduction in benzene and heptane insolubles, reduction in sulfur, nitrogen, and oxygen, an increase in hydrogen content, and a yield of lower boiling products. 

The preceding data lead to a comparison of Synthoil and SRC stocks in two respects—their relative susceptibility to upgrading by hydrorefining and their relative effect on catalyst stability. 

Table VI. Relative Response of Synthoil and SRC to Upgrading by Hydrotreatment...

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