Reforming n-heptane

Since the n-heptane reforming rate is much faster than catalyst deactivation rate, the reaction system considered, with appropriate assumptions, is represented by the following quasi-steady state mass balance equations ... 

Figure 9. n-Heptane reforming network over Pt-Re/Al203... 

Ni, which showed loss of activity at higher partial pressures of steam, probably due to oxidation.With Rh, AI2O3 was found to be a more stable support than SiOi, and the degree of dispersion of Rh on it was determined by Ha chemisorption and related to the activity of the catalyst for n-heptane reforming at 550—800 °C (Table 2). For high concentrations of Rh the activity was... 

TABLE 8,3. Change of Selectivity with Crystallite Size n-Heptane Reforming,... 

Toluene is a major aromatic constituent in catalytic reformate and one of the most important chemical intermediates obtained from this reaction. The kinetics of n-heptane reforming have been studied (39, 40), and the interest in toluene from this source antedates the use of platinum catalysts (76, 119, 145). While heptane is converted with considerably greater ease than hexane, this reaction is, on mass balance calculations, not sufficient to account for the toluene found in reformates. 

Little attempt seems to have been made to estimate the number of free surface metal atoms in coked catalysts, and hence to find TOFs, assuming these to be the seat of the residual activity. While the use of hydrogen chemisorption might be considered risky, that of carbon monoxide ought to be suitable. Based on the loss of its IR intensity, the active metal area of Pt/Al203 used for n-heptane reforming was only 8% of its initial value, but its extent of adsorption slowly increased as it displaced some of the carbon . ... 

In Europe, synthesis gas is mainly produced by steam reforming naphtha. Because naphtha is a mixture of hydrocarbons ranging approximately from C5-C10, the steam reforming reaction may be represented using n-heptane ... 

Nickel carbonyl has been shown to have a very high retention— 98.7%—both in the pure hquid and as 10% solution in n-heptane. It was argued that this represents the results following essentially complete isotopic exchange. Since the exchange of CO with Ni(CO)4 is known to occur quite rapidly by a dissociation mechanism, reformation of nickel carbonyl following the nuclear reaction would proceed rapidly by the reaction... 

For the n-Cq reforming and n-C[2 isomerization reactions the catalysts were run in a fixed bed micro reactor equipped with on-line GC analysis. The catalyst, together with a quartz powder diluent, was added to a 6 inch reactor bed. A thermocouple was inserted into the center of the bed. The catalysts were calcined at 350-500°C immediately prior to use and reduced in H2 at 350-500°C for 1 hour. n-Heptane or dodecane (Fluka, puriss grade) were introduced via a liquid feed pump. The mns were made at 100-175 psi with a H2/n-heptane (or n-Ci2) feed ratio of 7 and a weight hourly space velocity of 6-11. 

Figure 2-15 Reactions in catalytic reforming of n-heptane to 2,2,3-trimethylbutane and toluene.

The first suggestions concerning the mechanism of catalytic reforming were based on studies with hydrocarbon mixtures that permitted only observation of composition changes.91,98,120 It was observed, for example, that about 30% of the Ci—C4 product consisted of methane and ethane. These, however, are not common products in catalytic cracking processes. In fact, when n-heptane was hydrocracked, less methane and ethane were formed than expected, according to the stoichiometry of Eqs. (2.15) and (2.16). Therefore, C5 and C6 hydrocarbons were not considered... 

In view of the complicated reaction kinetics of multicomponent systems, it was not clear whether or not the diffusional effects would also affect the relative rate of conversion of feed molecules in a mixture. To answer this question we studied the hydrocracking of three multicomponent systems. The first was a C5-C8 mixture, a C5 360° C boiling range midcontinent reformate which contained 12.5 wt % n-paraffins including 4.2% n-pentane, 4.3% n-hexane, 2.9% n-heptane, l.l%n-octane, and <1% C9+ n-paraffins, with the remainder isoparaffins and aromatics. The reaction was carried out at 400 psig, 2 H2/HC, 2 LHSV, and 800°F. Secondly, a Cg-Cie mixture... 

Figure 1, Effect of mean Ni crystallite size (dx) in catalysts of series A on the coking rate and the length of the induction period in the steam reforming of n-heptane (H20 C = 25 1)...

The deactivation of a Pt-Re/AI203-d reforming catalyst was studied at moderate pressure using n-heptane as feed. A reactor which allows the analysis of the reaction products along the catalyst bed and the discharge of deactivated catalyst in discrete sections was used in this study. The coke was characterized by temperature-programmed oxidation (TPO). 

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