ABSTRACT
There is, nevertheless, a major focus on reneries through a variety of conversion processes on the ways in which heavy feedstocks might be converted into low-boiling high-value products (Khan and Patmore, 1997; Speight, 2011a, 2014). Simultaneously, the changing crude oil properties are reected in changes such as an increase in asphaltene constituents, and in sulfur, metal, and nitrogen contents. Pretreatment processes for removing those would also play an important role. However, the essential step required of reneries is the upgrading of heavy feedstocks, particularly residua. In fact, the increasing supply of heavy crude oils is a matter of serious concern for the petroleum industry.
