Novel Approaches for Deep Desulfurization

In Sections III, IV, and VI, several problems were identified that present obstacles to the achievement of the ultralow levels of sulfur demanded by new specifications for fuels in the not too distant future. These may be categorized into the following groups  

In this section, a number of published novel approaches are described that address these specific problems. Many new processes have been claimed, and it is certain that not all of these have been identified by the present authors. Several other reviews have some information relating to this specific topic (1,109,112,113), and it is suggested that those references be consulted as well. In addition, there have been two recent major symposia held by the American Chemical Society, Division of Petroleum Chemistry, that have dealt specifically with this topic (Washington, DC, August 1994, and Orlando, FL, August 1996). Papers presented at those symposia are also quite instructive. 

Novel Approaches That Have Been Reported 

The approaches can be divided into several categories, as follows  

Of these approaches, carbon-based catalysts seem to offer the greatest hope for novel catalysts with higher activities. To date, the varieties of carbons investigated have been extremely limited, considering the present state of the art in modifying the chemical and electrical properties of carbons. It is anticipated that future work in this area will provide some attractive new materials. Such catalysts may not be useful for fixed-bed operations with raw 

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