Hydrocarbon deposit

Sullivan, T.J. and M.C. Mix. 1985. Persistence and fate of polynuclear aromatic hydrocarbons deposited on slash burn sites in the Cascade Mountains and coast range of Oregon. Arch. Environ. Contam. Toxicol. 14 187-192. 

The catalyst can be treated with a solvent to extract hydrocarbon deposits. The most straightforward solvent to use is isobutane, which has been shown to restore catalytic activity only partially. Supercritical solvents have been tested, but they also lead to only partial restoration of the activity. Supercritical alkylation to remove the deposits in situ has been shown in Section III.D.l to be less effective. It is unlikely that this method of operation will lead to a competitive process. 

Petkovic, L.M. and Ginosar, D.M. (2004) The efiect of supercritical isobutane regeneration on the nature of hydrocarbons deposited on a USY zeolite catalyst utilized for isobutane/butene alkylation. Appl. Catal. A, 275, 235-245. 

Removal of nonvolatile hydrocarbons deposited on the catalyst by combustion in a stream of air... 

The search for structures able to be used as storage facilities differs from, and in a way is more complex than, the search for hydrocarbon deposits. In fact, just because a well has indicated a good, suitably covered reservoir does not mean that the structure is appropriate for storage purposes. It is necessary to prove that the gas to be stored there will not escape and therefore ensure the caprock s continuity and the closure of the structure. 

Tuhackova, J., T. Cajthaml, K. Novak, et al. 2001. Hydrocarbon deposition and soil micro flora as affected by highway traffic. Environ. Pollut. 113 255-262. 

When considering the higher hydrocarbons present in natural gas it is probably best to recall that a continuum exists in oil and gas reservoirs from almost pure methane to heavy petroleum oils and waxes. In general, hydrocarbon deposits do not span to the extremes higher hydrocarbon free natural gas is not commonly accounted although there are some very large natural gas deposits which comprise almost entirely methane . Thus many oil reserves have considerable quantities of associated gas and most gas reserves have associated with them light oil (condensate) deposits. 

Most coal-derived liquid hydrocarbon deposits are of Late Cretaceous or Tertiary age. Only four known deposits are of Paleozoic age (Clayton, 1993). The age distribution of coal-derived petroleum does not correspond to the worldwide age distribution of coal deposits (Figure 3), as —60% of the world s coals are Permian or older (Bouska, 1981). Evolutionary changes in the biopolymers characteristic of vascular plants may have contributed to the greater abundance of coal-derived petroleum from Late Cretaceous and younger coals. 

Tima A. C., Eglinton T. L, and Reddy C. M. (2003) High resolution record of pyrogenic polycyclic aromatic hydrocarbon deposition during the 20th Century. Environ. Sci. Technol. 37, 53 -61. 

To finish this duscussion on lipophorin biosynthesis we will mention studies on the origins of PLs, hydrocarbons, sterols, and carotenoids. It has been reported that in adult M. sexta and Rhodnius prolixm PL can be transferred from fat body to lipophorin (Van Heusden et al., 1991 Correa et al., 1992). This transfer of PL is independent of de novo synthesis of lipophorin however, the mechanism by which it occurs is unknown. Hydrocarbon transport by lipophorin has been studied only in P. ameri-cana. Katase and Chino (1982) have shown, in in vitro incubations, that a fat body rich in oenocytes, one type of cell in the hemolymph, which is the major site of hydrocarbon biosynthesis (Diehl, 1975), can release labeled hydrocarbon to lipophorin. It was also shown, using in vitro incubations, that the labeled hydrocarbon in lipophorin was delivered to the epidermis, the normal site of hydrocarbon deposition in insects. The sterols and carotenoids that are present in lipophorin must arise from the diet, because insects cannot biosynthesize either sterols or carotenoids de novo. Chino and Gilbert (1971) have shown that sterol can be transferred from the midgut to lipophorin, and the same is most likely true for carotenoids. The mechanism by which hydrocarbons, sterols, and carotenoids are transferred from either oenocytes or midgut epithelial cells to lipophorin is unknown. 

In the Sheep Mountain anticline of the Bighorn Basin, Wyoming, areas of red-bed bleaching within the Chugwater Formation correspond spatially with known hydrocarbon deposits. Malhotra et al. (1989) outlined bleached areas from Landsat TM imagery by a decrease in the ratio of bands 3 1 in conjunction with an increase in total reflected radiance. 

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