Heteroatom removal during

Figures 13 and 14 also show that hydrotreating the catalytic cracker feedstock increases the zeolite cracking. C3, and C5+ compounds are possible products of primary zeolite cracking. These figures show that hydrotreating of the feedstock results in larger yields of these primary cracking products and hence more valuable products. This improvement is most likely due to the heteroatom removal and the saturation of aromatic compounds during hydrotreating which tend to block active sites and reduce the activity of the catalyst.

Using the assumptions outlined above, an estimate of hydrogen requirements for heteroatom removal can be made. This estimate is shown in Table IV. This particular shale oil is, in fact, the Paraho shale oil (direct heated mode) which was hydrotreated for the U.S. Navy by The Standard Oil Company (Ohio). Results from hydrotreating tests on this oil were reported by Robinson (3). The hydrotreater was said to add about 1,600 SCF per barrel of shale oil feed (12.05 kmol/m3). However, complete heteroatom removal was not achieved during hydrotreating. The composition of the hydrotreated whole shale oil was reported as ... 

During thermal hydrotreating, heavy molecules crack into smaller ones, thereby favoring the catalytic action for sulfur and other heteroatoms removal (Kin et al., 1998). When a catalyst is present, the thermal reactions occur in the space between catalyst particles, in the liquid phase, and also in the gas phase, and they are nonsensitive to hindrance restrictions (Rahimi and Gentzis, 2003). 

Oxidation of iodoalkanes involves removal of an electron from the halogen nonbonding orbital. The radical-cations of primary and secondary alkyl iodides can be identified in aqueous solution by their absorption spectra and have half-lives of microseconds [1]. They are formed during pulse radiolysis of the iodoalkane in aqueous solution in the presence of nitrous oxide. This system generates hydroxyl radicals, which remove an electron from the iodine atom lone pair. Iodoalkane radical-anions complex with the lone-pair on other heteroatoms to form a lollo three-electron bond. In aqueous solution, the radical-cation of iodomethane is involved in an equlibrium indicated by Equation 2.1. 

Heteroatoms do affect every aspect of refining. Sulfur is usually the most concentrated and is fairly easy to remove many commercial catalysts are available that routinely remove 90% of the sulfur. Nitrogen is more difficult to remove than sulfur, and there are fewer catalysts that are specific for nitrogen. If the nitrogen and sulfur are not removed, the potential for the production of nitrogen oxides (NOx) and sulfur oxides (SOx) during processing and use become real. 

As can be observed in Scheme 70, these transformations have parallels with well-established selenium processes.195 Contrary to the cyclofunctionalization using selenium reagents, the tellurium version does not tolerate the presence of amines to capture the HC1 formed during the process, since amines react with organotellurium trichlorides.5,196 In this way, although several cyclizations can be successfully performed using tellurium electrophiles, the selenium methodology continues to be the method of choice for this purpose in view of the milder cyclofunctionalization conditions and the easier removal of the heteroatom at the end of the process. 

During the pyrolysis of mixed waste plastic, one of the main problems associated with the feedstock recycling is the presence of plastic containing hetroatoms, e.g. PVC, ABS, PVDC, etc. Efforts are made to remove the heteroatoms before pyrolysis. Chlorine can be removed either by thermal degradation or by using a catalyst. The HCl generated in the process can be used as industrial hydrochloric acid. 

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