Desulfurization technology

ExxonMobil extended the Hydrofining technology to produce a 200 ppm diesel, with the Diesel Oil Deep Desulfurization technology, DODD. The reactor is packed with multiple beds of different catalysts. A preceding history of commercial experience provided data to build a model for deep HDS and pave the way to a new technology, MAK Fining. 

The present review summarizes contemporary views of the problems, achievements, and prospects involved in the deep desulfurization of gas oils, including identification and reactivity of sulfur species in the feed, the reaction pathways and mechanisms, activity and selectivity of the conventional catalysts, and concerns of fluorescence color production. Process schemes and guidelines for the development of the next-generation catalysts for improved deep desulfurization technology based on these discussions are also proposed. The structure and nature of the active sites of current catalysts will not be extensively covered in this review, because several excellent reviews have been published on these subjects within the past two years (1-3). 

The first option is to eliminate the generation of the reactive desulfurization slag by substituting calcium carbide with some other material. A few large foundry companies have made major advancements in new desulfurization technologies over the past years. One such process involves the use of a mixture of calcium oxide, calcium fluoride, and two other materials. One foundry reports that, not only is the product quality satisfactory, but the plant has eliminated the generation of a major problem hazardous waste, and the economics of the process are actually better than calcium carbide desulfurization. 

Lei, Zhongcun (2001). Industrial Desulfurization Technologies. The Chemical Industry Press of China. Beijing (in Chinese). 

Although the selective oxidation of coal has been extensively studied (31-33, surprisingly little has been reported about sulfur species in the oxidation products. Even less is known about the distribution of organic sulfur species between different coal macerals despite the fact that this information is important for the development of any future desulfurization technology. 

Satriana, M., ed., "New Developments in Flue Gas Desulfurization Technology," Noyes Data Corporation, Park Ridge, N.J., 1981. 

That leaves us with the challenge to desulfurize the coke itself. There has long been an incentive to remove sulfur from coke since low sulfur coke has always commanded a premium price over its higher sulfur counterpart. There have been dozens of patents filed on petroleum coke desulfurization technology (1-18). Although far from exhaustive, the list of 18 patents cited are those most pertinent to this discussion. 

It is clear from Figure 5 that the combination of natural low sulfur fuels and fine gas desulfurization technology will not control the quantity and size range of combustion capacity required to achieve national ambient air quality standards. Thus, a third category of control technology, fuel desulfurization, is also included in Figure 5. These processes for not only desulfurization but total pollutant cleanup of coal and residual oil are required to achieve ambient air quality standards. Their basic role is two fold ... 

This strategy not only uses the limited low sulfur fuels available to better advantage in achieving ambient air quality, but it also reduces the demand for effluent desulfurization technology from the 20,000 units and 150,000 MW indicated by the roll-back strategy to about 200 utility steam generators with a total capacity of 45,000 MW. This capacity is essentially all coal fired. 

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