Reduction in sulfur

These developments will reduce the total emissions of SO2 but the effect will remain limited. The reduction in sulfur levels in diesel fuel from 0.2 to 0.05% Is admitted to reduce yearly emissions of SO2 in France to only 10 to 12%. 

Air Pollution. Particulates and sulfur dioxide emissions from commercial oil shale operations would require proper control technology. Compliance monitoring carried out at the Unocal Parachute Creek Project for respirable particulates, oxides of nitrogen, and sulfur dioxide from 1986 to 1990 indicate a +99% reduction in sulfur emissions at the retort and shale oil upgrading faciUties. No violations for unauthorized air emissions were issued by the U.S. Environmental Protection Agency during this time (62). 

A variety of models have been developed to study acid deposition. Sulfuric acid is formed relatively slowly in the atmosphere, so its concentrations are beUeved to be more uniform than o2one, especially in and around cities. Also, the impacts are viewed as more regional in nature. This allows an even coarser hori2ontal resolution, on the order of 80 to 100 km, to be used in acid deposition models. Atmospheric models of acid deposition have been used to determine where reductions in sulfur dioxide emissions would be most effective. Many of the ecosystems that are most sensitive to damage from acid deposition are located in the northeastern United States and southeastern Canada. Early acid deposition models helped to estabUsh that sulfuric acid and its precursors are transported over long distances, eg, from the Ohio River Valley to New England (86—88). Models have also been used to show that sulfuric acid deposition is nearly linear in response to changing levels of emissions of sulfur dioxide (89). 

The new Clean Air Act will result in a permanent 10 million ton reduction in sulfur dioxide (SOj) emissions from 1980 levels. To achieve this, EPA will allocate allowances of one ton of sulfur dioxide in two phases, The first phase, effective January 1, 1995, requires 110 powerplants to reduce their emissions to a level equivalent to the product of an emissions rate = (2,5 lbs of S02/mm Btu) x (the average mm Btu of their 1985-1987 fuel use). Plants that use certain control technologies to meet their Phase 1 reduction requirements may receive a two year extension of compliance until 1997. The new law also allows for a special allocation of 200,000 annual allowances per year each of the 5 years of Phase 1 to powerplants in Illinois, Indiana and Ohio. 

Consequently, environmental regulations affect each fuel composition in different ways. For gasoline, requirements include a reduction in sulfur, nitrogen, olefins and... 

Effect ofNOa- on G(Ce+8). There is a striking effect (43) of NO on Ce+4 reduction in sulfuric acid solutions. T1 + increases (44) G(Ce+s) from 2Gh o, + GH — G0Hto 2Gh,o, + Gh + G0h. N08 at concentrations greater than 0.01 M markedly enhances G(Ce +a) both in the presence and absence of T1 +, the effect being approximately equal in both cases. Mahlman (24) confirmed this effect and extended the study from 0.5M to 5.0M. The enhancement, AG(Ce+3), for NOs concentrations from O.lilf to 5.0M is quantitatively expressed by Equation 1 as shown in Figure 1. 

In every case, the liquid products show substantial reductions in sulfur con-... 

Accordingly, two phenomena are observed involving the effect of carbon black. One is the reduction in sulfur rank for the Ale sulfide structure, and the other, is the formation of the A1 type product at an earlier cure stage and an increase in the B1 products at a later stage. 

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. 

Other than a slight reduction in sulfur content the filtrate appeared to be thermally stable. Heptane insolubles showed little consistent change. This would be expected since these conditions are very similar to the solvent-refining process environment. 

Because of the increased sulfur and impurity levels in crudes currently being processed, refiners in recent years have been considering residue desulfurization units upstream of the delayed coker. In addition to the reduction in sulfur content, residue desulfurization units also lower the metals and carbon residue contents. Due to the reduction in the carbon residue, the liquid product yield is increased and the coke yield reduced. In addition, the coke produced from a desulfurized residue may be suitable for use as anode grade coke. Table I shows the yields and product properties after coking Medium Arabian vacuum residue, with and without upstream residue desulfurization. 

This similarity in volumes conceals enormous structural changes in the industry s sources of supply. Table 25.1 summarizes the dramatic shifts in the sources of sulfur during this period. It shows, for example, the virtual demise of Frasch and native sources of supply, and a 54 percent reduction in sulfur values derived from sulfuric acid pyrites roasting offset by huge increases in recovered sulfur (59%) plus added sulfuric acid and S02 recoveries from metallurgical smelting, (59%). 

When the reduction is performed without control of the potential, a mixture of products results. Thus, reduction in sulfuric acid at lead or mercury cathodes of the pyridine carboxylic acids leads to a mixture of picolines andtetra- and hexahydropyridine derivatives.284-287 Derivatives of nicotinic acid are more apt to be reduced in the ring than the 2- and 4-carboxypyridines. Reduction of the corresponding pyridylcarbinoles under identical conditions produces a similar reaction mixture.287... 

The recycle characteristics of coal-derived oil are very Important for the commercialization of a liquefaction process. One subbituminous coal from the Sheridan field of the Powder River Coal Basin was studied for Its recycle characteristics and found to be quite acceptable. After nine recycles the viscosity of the product oil remained low and about 957. reduction In sulfur level to 0.22 wt% was achieved. Sucdi a liquefaction process holds promise for those Western coals that have high sulfur and high ash and cannot be economically transported to distant markets. 

In many reductions a lead cathode yields the same kind of product as a mercury electrode, but in some cases it is either inferior or superior to mercury. The latter is found in the reduction in sulfuric acid of aromatic acids to the corresponding alcohols. In such cases, specific adsorption of the substrate at the electrode may partly exclude the discharge... 

Among the azomethine derivatives of hydroxylamine, the ordinary oximes are the most important, and many polarographic and electrolytic investigations of oximes have been made [1,85,86]. Most oximes are reducible in acid solution, and only few in alkaline solution polarographic data prove that it is the protonated oxime that is the reducible species in acid and neutral solutions. Classic reductions in sulfuric acid at lead cathodes or controlled potential reductions in acid solution at mercury cathodes yield the amine in a four-electron reduction. As the hydroxylamine corresponding to the oxime is not reducible under the conditions employed, it has been suggested [1] that the reduction proceeds as in ... 

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