Effect desulfurization methods

Deep desulfurization method of fossil fuels, comprising a first step of HDS and a BDS step for the removal of HDS sulfur refractory compounds, using an effective amount of a biocatalyst. The fuel is incubated in the presence of one or more BDS-active microorganisms, which converts the organic sulfur compounds into water-soluble inorganic sulfur. Then, in a separation stage, the products of the incubation are separated into a deeply desulfurized liquid fossil fuel, and the water-soluble inorganic sulfur. 

Raney nickel desulfurization of thiophenes is an important technique of chain extension. Ring fission is accompanied by saturation of the ring carbon atoms and chain extension by four carbon atoms is effected. This method has been widely used to prepare alkanes, ketones and carboxylic acids and their derivatives (B-74MI30200). An illustrative example is given in Scheme 38 see also CHEC 1.16 and CHEC-II(2)522. 

Desulfurization. Helmkamp and Pettitt23 found that ci.v-2,3-dimethylthirane can be desulfurized by refluxing with methyl iodide in acetone the products are cis-2-butene and trimethylsulfonium iodide. Later, Pettitt and Helmkamp24 used the method to effect desulfurization of eye looctene sulfide. 

All these methods are specific to the precombustion removal of inorganic sulfur and are expensive when applied to the large quantities of coal burned in power stations. The organic sulfur retained within the carbonaceous structure represents an appreciable contribution to acid rain and, therefore, these methods may not provide effective desulfurization. 

Oil palm ash was utilized as an absorbent for dry-type flue gas desulfurization. The absorbents were prepared using water hydration method with the addition of other chemicals such as CaO and CaS04. The absorbents were then subjected to synthetic flue gas under various SO2 feed concentration (500 to 2000 ppm) and reaction temperature (65°C to 400°C). It was foimd that higher feed SO2 concentration reduces the time the absorbent could maintain 100% removal of SO2. On the other hand, higher reaction temperature was found to increase the reactivity of the absorbent. However, reaction temperature above SOO C was found to have negative effect on the reactivity of the absorbent. 

PEC. The patent includes the production method for the biocatalyst, with a characteristic inhibitory effect on certain enzyme expression. The expression recombinant vector contains a promoter free from manifesting inhibition due to an inorganic sulfur compound or a sulfur-containing amino acid. The recombinant microorganism also contains a gene for desulfurizing the sulfur-containing heterocyclic compound. 

Successive substitution is the simplest although generally the least effective method for performing these calculations. Values are assumed for one or more of the unknown variables other variables are then determined from some of the equations new values of the assumed variables are determined from the remaining equations. The process is repeated until convergence is obtained. For flue gas desulfurization examples, many of the variables are highly constrained, and the calculation sequence can easily move into infeasible regions. The solution sequence frequently oscillates. 

An application in power production, particularly in coal-fired power plants, is the analysis of flue gas scrubbers which remove excess SO2 following coal combustion. Tests run by SAMBESRL at the EPA s Research Triangle Park facility (8,9) have demonstrated the effectiveness of IC in determining sulfite and sulfate in flue gas desulfurization systems. Table III gives results of direct IC analysis of scrubber liquors compared with turbidimetric and titration methods. 

Tokitoh and co-workers further succeeded in the synthesis of overcrowded diarylstannylenes, Tbt(Tcp)Sn (170 Tcp = 2,4,6-tricyclohexylphenyl) and Tbt (Tpp)Sn [171 Tpp = 2, 4,6-tris(l-ethylpropyl)phenyl], by the exhaustive desulfurization of the corresponding tetrathiastannolanes with a trivalent phosphine reagent (Scheme 14.74). Since only a few convenient precursors have been available for the generation of stannylenes, this new method should provide us with a useful synthetic route for a variety of overcrowded stannylenes. The successful synthesis of a series of Tbt-substituted diarylstannylenes enabled the systematic comparison of their electronic absorptions with those of the previously reported overcrowded diarylstannylenes, which led to the elucidation of the substituent effect on the n—transition of stannylenes. 

Foundries that generate furnace dusts that are EP-Toxic due to lead and cadmium have found that by carefully mixing the dusts with water treated calcium carbide desulfurization slag (which contains calcium hydroxide), they may be rendered non-EP-Toxic. Great care must be taken with this method since at high pH levels the lead may leach out. In addition to this problem, the effect of other hazardous materials in the dust and in the slag may still render this waste as hazardous (Stephens 1988). 

The effects of reactor type, process variables and feedstock type, catalysts, and feedstock composition (Chapters 5 and 6) on the desulfurization process provide a significant cluster of topics through which to convey the many complexities of the process. In the concluding chapters, examples and brief descriptions of commercial processes are presented (Chapter 7) and, of necessity, some indications of methods of hydrogen production (Chapter 8) are also included. 

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