n-Alkane hydroconversion over carbided molybdena supported on sulfated zirconia

Abstract

A carbided molybdena on sulfated zirconia support has been prepared by in situ exposure to a methane/ hydrogen mixture at 650°C and the characteristics established using N 2 adsorption and X-ray diffraction. The activity of the catalyst in the hydroconversion of C 6 to C 9 n-alkanes was investigated in the temperature range 350-450°C at 1 atm pressure. Activity and selectivity were found to show strong dependence on the choice of n-alkane with reaction rates found to be higher for the shorter alkanes. n-Hexane and n-heptane were hydroisomerised to the corresponding C6 and C7 isomers with high selectivity while the higher alkanes, especially nonane, produced mainly hydrocracking products. The catalyst offers a potential system for the upgrading of light naphtha range paraffins.

Catalytic Hydrogenation of Hydrocarbons for Gasoline Production

“…1,2 Meanwhile, it is a well-known fact that the major components of fuel used in internal combustion engines comprise mainly of straight chain and isomers of light and medium alkanes with specific concentration of aromatics due to environmental policies, but are good for the optimisation of octane number. [1][2][3][4][5] Refinery operations generally produce several streams of products that are typically quantified as functions of hydrocarbons sources used in various processes in generating high grade fuels. However, all these products contain valuable petrochemical components which at stages of productions require improved processing to extract them in more valuable forms.…”

Catalytic upgrading of refinery cracked products by trans-hydrogenation: a review

“…However, its exact chemical composition can be varied by blending with other specific hydrocarbons to produce a very high grade fuel depending on the demand, applications and environmental constraints. The major component of fuel used in internal combustion engines comprises of mainly straight chain and isomers of light and medium alkanes with specific concentrations of aromatics to achieve an optimum octane number [5][6][7]. Environmental problems associated with aromatics, however, have placed a ban on their usage recently due to health concerns [8,9]; even with the recent ban, gasoline will remain a popular fuel for transportation, combustion engines and industrial applications [10,11] for many years to come.…”

n-Heptane hydroconversion over sulfated-zirconia-supported molybdenum carbide catalysts

“…The hydroisomerisation of C4-C6 hydrocarbon is performed on industrial scale, but there is no established catalyst for heptane isomerisation [4,5]. Solid acid catalysts (such as platinum on chlorided alumina) that operate at low temperature (\423 K) are the current preferred catalysts used in refineries, because they give high activity at low temperature, which favours isomer yield, given the exothermicity of the isomerisation reaction [4,6,7]. The problem of corrosion and waste disposal are the major challenges with this type of catalysts.…”

“…Another example of catalyst that has been widely reported to be active at low temperature is a catalyst based on sulfated zirconia [8][9][10][11][12][13]. However, this type of catalyst appears susceptible to deactivation which appears to originate from high levels of carbonaceous deposits derived from cracking of higher alkanes, poor resistance to poisons such as water, and sulfate loss at high temperature [6,14,15].…”

“…The carbon donates its valence electron into the outer d band of Mo resulting in the appearance of a narrower metallic type band with a density of states at the Fermi level similar to that of a noble metal [18,19]. As a consequence, this permits their use in a wide variety of reactions including: dehydrogenation [20,21], hydrogenation [16], methane dehydroaromatisation [22], methane reforming [23,24], methane capturing [25], methanol oxidation [26], alcohol synthesis [27,28], alkyne metathesis [29], CO hydrogenation [30], water-gas shift [31,32], hydroisomerisation [6,[33][34][35] and hydrotreating [36].…”