Reforming methylcyclopentane

Table VII shows some results obtained in reforming methylcyclopentane, and it is noteworthy that there appear to be striking differences between these data and the earlier results with cyclohexane. When compared at similar space velocity and pressure conditions, the conversions (and particularly the selectivities) are markedly poorer than those in the cyclohexane case despite the use of higher temperatures. The selectivity would be still poorer at higher pressures.

The illustrated unit can be used to study vapor-phase reforming of kerosene fractions to high octane gasoline, or hydrogenation of benzene, neat or in gasoline mixtures to cyclohexane and methylcyclopentane. In liquid phase experiments hydrotreating of distillate fractions can be studied. The so-called Solvent Methanol Process was studied in the liquid phase, where the liquid feed was a solvent only, a white oil fraction. 

Hydrogenolysis of 2-methylpentane, hexane, and methylcyclopentane has been also studied on tungsten carbide, WC, a highly absorptive catalyst, at 150-350 °C in a flow reactor [80], These reforming reactions were mainly cracking reactions leading to lower molar mass hydrocarbons. At the highest temperature (350 °C) all the carbon-carbon bonds were broken, and only methane was formed. At lower temperatures (150-200 °C) product molecules contained several carbon atoms. 

Fig. 1. Reaction composition profile. Reforming at 794 K, 2620 kPa. Zone A dehydrogenation zone zone B isomerization zone zone C hydrogenation and cracking zone. [Charge stock A, hexane (HEX) , benzene (BENZ) V, cyclohexane (CH) O, methylcyclopentane (MCP).]...

Similar arguments can be made for the effects of temperature on the reforming of a methylcyclopentane-hexane mixture at 2620 kPa, as shown in Fig. 17. Higher temperatures favor the benzene formation. 

Benzene, naphthalene, toluene, and the xylenes are naturally occurring compounds obtained from coal tar. Industrial synthetic methods, called catalytic reforming, utilize alkanes and cycloalkanes isolated from petroleum. Thus, cyclohexane is dehydrogenated (aromatization), and n-hexane(cycli> zation) and methylcyclopentane(isomerization) are converted to benzene. Aromatization is the reverse of catalytic hydrogenation and, in the laboratory, the same catalysts—Pt, Pd, and Ni—can be used. The stability of the aromatic ring favors dehydrogenation. 

Pt-Re sulfided, A1203 support Hydrogenolysis and reforming of n-hexane and methylcyclopentane. Coke deposition measured. 

Pt-Re Pt-Ir A1203 support Chemisorption of H2 and CO. Reforming of heptane, methylcyclopentane, and naptha. 

J.N. Beliramini and R. Datta, React. IQnetics and Catalysts Ijetters, in press. J.N, Beltramini, T.J. Wessel, and R. Datta, Kinetics of Deactivation of FVAtaOg-Cl catalysts by Coking During Methylcyclopentane Reforming, submitted for publication. 

The studies of n-heptane and methylcyclopentane conversion provide insight into the advantages of platinum-iridium and platinum-rhenium catalysts over catalysts containing only one of the transition metal components, that is, platinum, iridium, or rhenium. If, for example, we consider an iridium-alumina catalyst for the reforming of a petroleum naphtha fraction, we find that it produces a substantially higher octane number reformate than a platinum on alumina catalyst under normal reforming conditions. The iridium-alumina catalyst will also exhibit a lower rate of formation of carbonaceous residues on the surface, with the result that the maintenance of activity with time will be much superior to that of a platinum-alumina catalyst. 

A catalyst consisting of platinum dispersed on an acidic alumina is a very effective dual function catalyst, used in petroleum reforming of naphtha and also for paraffin isomerization. The conversion of naphtha constituents such as methylcyclopentane, MCP, to benzene, B, is desired in order to increase octane rating. The reaction pathway for conversion of MCP to B is illustrated in Fig. 3 . MCP is first dehydrogenated on a platinum site to the olefin of the same structure. The olefin then transfers to an acidic site where it is isomerized to cyclohexene. This olefin proceeds to a platinum site where it is dehydrogenated to B and H2. In the diagram, vertical movement represents hydrogen subtraction or addition and horizontal movement represents isomerization. 

The low reactivity of hexane and methylcyclopentane accounts for the relatively low benzene content in reformates (see Tables II and IV). Since the direct preparation of benzene by catalytic reforming would be economically attractive, considerable effort has been devoted to modifications (124-131) designed to achieve this end. 

Figure 14 (left) Coke formation on 0.2 g of catalyst as a function of time in methylcyclopentane reforming. Same operational conditions and numbers as in Figure 13. ... 

Figure 15 (right) TPO of coked catalysts after the 7 h of methylcyclopentane reforming (end of runs in Figure 14). Same numbers as in Figure 13.35...

Figure 18 (left) Concentration of methylcyclopentane in the effluent as a function of chloride concentration on Pt(0.3)-Re(0.3)/AI2O3 during naphtha reforming. F = fresh catalyst, C = coked catalyst.56... 

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