Characterization of coal liquids

Abstract

The objective of this investigation is to evaluate the process-ability of the primary products of coal liquefaction generated by three ERDA sponsored processes: Synthoil, Solvent Refined Coal (SRC), and H-Coal. The study entails actual bench scale processing of coal liquids and an in-depth analytical characterization of charge and product streams. The results are intended to indicate the nature and degree of possible upgrading of primary coal liquids using technology now available in the petroleum refining industry. Six primary coal liquids were filtered and hydrotreated under commercial conditions, using a fixed bed of commercial catalyst. These included Synthoil, H-Coal hydroclone underflow, and four SRC process streams--SRC filter feed, SRC filtrate and solvent refined coal itself, both neat and cutback with process solvent. In all cases catalytic hydrotreating was able to substantially eliminate sulfur and benzene insoluble matter. A 90% reduction of heptane-insoluble matter and 80% reduction in N content could be achieved with SRC and H-Coal liquids. Catalyst stability was affected by metals and particulates in the feed. None of the products, as received, can be considered an acceptable feedstock to a conventional fixed bed hydrotreating unit. The ash remaining will agglomerate with the solid catalyst pellets and shorten catalyst life. Two of the hydrotreated coal oils, Synthoil and SRC, were further processed under commercial conditions over a fixed bed of commercial hydrocracking catalyst. Catalyst stability was unsatisfactory when the total upgraded products were processed. An asphaltene-free vacuum gas oil derived from hydrotreated Synthoil responded satisfactorily to hydrocracking.