Linear aliphatic hydrocarbons

A very serious problem was to clear up the formation of hydroperoxides as the primary product of the oxidation of a linear aliphatic hydrocarbon. Paraffins can be oxidized by dioxygen at an elevated temperature (more than 400 K). In addition, the formed secondary hydroperoxides are easily decomposed. As a result, the products of hydroperoxide decomposition are formed at low conversion of hydrocarbon. The question of the role of hydroperoxide among the products of hydrocarbon oxidation has been specially studied on the basis of decane oxidation [82]. The kinetics of the formation of hydroperoxide and other products of oxidation in oxidized decane at 413 K was studied. In addition, the kinetics of hydroperoxide decomposition in the oxidized decane was also studied. The comparison of the rates of hydroperoxide decomposition and formation other products (alcohol, ketones, and acids) proved that practically all these products were formed due to hydroperoxide decomposition. Small amounts of alcohols and ketones were found to be formed in parallel with ROOH. Their formation was explained on the basis of the disproportionation of peroxide radicals in parallel with the reaction R02 + RH. 

Catalytic Dewaxing Also called CDW. A hydiocracking process for removing waxes (linear aliphatic hydrocarbons) from petroleum streams by converting them to lower molecular weight hydrocarbons. The catalyst is a synthetic mordenite. Developed by BP two units were operating in 1988. 

MLDW [Mobil lube dewaxing] A catalytic process for removing waxes (long-chain linear aliphatic hydrocarbons and alkyl aromatic hydrocarbons) from lubricating oil. Developed by Mobil Research Development Corporation and operated at Mobil Oil refineries since 1981. Eight units were operating in 1991. 

Molex A version of the Sorbex process, for separating linear aliphatic hydrocarbons from branched-chain and cyclic hydrocarbons in naphtha, kerosene, or gas oil. The process operates in the liquid phase and the adsorbent is a modified 5A zeolite the pores in this zeolite will admit only the linear hydrocarbons, so the separation factor is very large. First commercialized in 1964 by 1992, 33 plants had been licensed worldwide. See also Parex (2). 

Parex (2) [Paraffin extraction] A process for separating linear aliphatic hydrocarbons from branched-chain and cyclic hydrocarbons by means of a zeolite 5 A adsorbent. The products are desorbed with a mixture of steam and ammonia. Developed in the mid-1960s by Luena-Werke and Schwedt in East Germany and operated in East Germany, Bulgaria and the USSR. Broadly similar to Molex and not to be confused with Paiex (1). 

Many microwave extractions can reach maximum recovery in 10 to 20 minutes. Longer extraction time is not necessary and may lead to the decomposition of thermolabile analytes. It was reported that the recovery of sulfonylurea from soil was not affected by extraction time in the range 5 to 30 minutes [79], Similar observation was made in the extraction of PAHs from soils and sediments [6], In the extraction of PAHs and LAHs (linear aliphatic hydrocarbons) from marine sediments, the extraction time was found to be dependent on the irradiation power and the number of samples extracted per run [81], When the irradiation power was 500 W, the extraction time varied from 6 minutes for one sample to 18 minutes for eight samples [74], The recovery of OCPs from spiked marine sediments increased from 30% at 5 and 10 minutes to 60% at 20 minutes and to 74 to 99% at 30 minutes [82],... 

The activity and selectivity of catalyst HZSM5-1 was constant over 1 hour on stream although the formation of a linear hydrocarbon species at the catalyst was noticed. The IR spectra suggest that this species is a linear aliphatic hydrocarbon (coke precursor) increasing in concentration with time on stream [13], It is concluded that this species is adsorbed at the (catalytically inactive) Si-OH groups of the catalyst. During our measurements, the catalytically active Si-OH-AI groups were not blocked by this surface species and the product selectivity was not altered... 

The Fischer-Tropsch catalysis of converting syngas to predominantly linear aliphatic hydrocarbons has been extensively reviewed (350-354). A related process, converting syngas to oxygenates and hydrocarbons over zeolite-supported Pd catalysts, will be briefly described here. 

Primary alkyl radicals from linear aliphatic hydrocarbons, type H(CH2) CH2, n O ... 

Hydrocarbons are transformed into a variety of products under hydrogenation conditions. The heterogeneous catalyst is Pt which is a very reactive metal (also used as CO oxidation catalyst for automobile exhaust systems and in various other reactions). Linear aliphatic hydrocarbons are transformed into aromatics (dehydrocycli-zation) and branched hydrocarbons (isomerization). 

Aikyiated Aromatics At present, the only products in this category are linear alky-benzenes. As is the case with the linear paraffins, they are high in purity and low in color and odor. They are less volatile and more compatible than the linear paraffins. They are also used to reduce the viscosity of plastisols. Because the viscosity of dode-cylbenzene is about four times that of a Cjs linear aliphatic hydrocarbon, it is about 25 percent less effective in reducing plastisol viscosity. Often, linear alkylbenzenes are available in blends with linear paraffins. 

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