N-Heptane hydrogenolysis

Distribution of n-Heptane Hydrogenolysis Products Over Metals (23)... 

TABLE 7.19. Kinetic Parameters for n-Heptane Hydrogenolysis Over Metal Catalysts... 

Figure 14.1. Compensation plot of Arrhenius parameters for the reactions of (i) neopentane and (ii) n-heptane with hydrogen on various supported metals. They are compared with selected values for ethane hydrogenolysis, the lines being those used to classify the activities of metals for that reaction in Chapter 13 (see Figures 13.3-13.8). Ethane hydrogenolysis Q n-heptane hydrogenolysis v neopentane hydrogenolysis 3 neopentane isomerisation [1.

In the preparation of faujasite zeolite-supported Pt-Re catalysts, bimetallic PtRe clusters have been reported to be predominantly formed when a carbonyl rhenium precursor (Re2(CO)io) is contacted with zeolite in which platinum has been previously introduced and reduced. The preexisting Pt clusters may act as nucleation sites. After reduction, these Pt-Re systems show a high selectivity to CH4 in the hydrogenolysis of n-heptane [58]. 

Re2(CO)io Pt/NaY Pt/NaHY Adsorption from vapor phase PtRe clusters, deep hydrogenolysis of n-heptane [58]... 

Li and Klabunde (72) utilized a pulse reactor (normal pressure) to carry out n-heptane conversions. Pt and Sn were evaporated into a solvent at low temperature following evaporation the solvent was allowed to warm to room temperature where agglomeration of atoms took place to produce a dispersion of colloidal particles that were then added to an alumina support. These catalysts were compared to conventional Pt-Sn-alumina catalysts for n-heptane conversion. The authors proposed that the presence of small amounts of Sn° on the surface of Pt can cause both an increase in catalytic activity and a decrease in hydrogenolysis. 

As in the case of hydrogenolysis of cyclopentane, the change in selectivity observed in pulse and flow systems for the 1-5 dehydrocyclization of n-heptane to ethylcyclopentane and 1,2-dimethylcyclopentane, for instance, was interpreted by two modes of adsorption involving five or seven carbon atoms in contact with the surface (775) (Fig. 3). 

The reaction rates were determined at low conversion levels (7-12%) in an attempt to minimize the effects of secondary reactions. The inlet stream to the reactor contained five moles of hydrogen per mole of n-heptane. The n-heptane contained 0.5 ppm sulfur, and the reaction rates were determined after 40 hours on stream. The catalysts contained 0.9 wt% chlorine as charged. Prior to the runs the catalysts were contacted with an H2S-containing gas until H2S was detected at the reactor outlet (34). This step is routinely employed with platinum-rhenium and platinum-iridium catalysts to suppress hydrogenolysis activity (33). 

The application of the strong base method to liquid biphase hydrogenolysis reactions has provided quite interesting results using the SULPHOS complex 3 as catalyst precursor, BT as substrate and NaOH as base [10]. In a typical reaction in H20—MeOH/n-heptane (BT/NaOH/3 = 100 100 1, 30 bar H2), all the substrate is selectively transformed into 2-ethylthiophenol sodium salt (ETPNa the production of DHBT is generally less than 1%) (Scheme 2). At 200°C, however, appreciable decomposition of the catalyst has been observed to give metal particles that are responsible for heterogeneous HDS of BT to ethylbenzene and H2S. 

Chloro-l-phenylpropene (cinnamyl chloride) was reductively dehalogenated in water/n-heptane biphasic systems by hydrogen transfer from formates using Pd(II) complexes with sulfonated phosphine ligands of the type 21 (Scheme 3.38) [271], Addition of polyether detergents increased the rate of hydrogenolysis and supressed the formation of alcohol... 

Monometallic Pt/H-BEA and Pd/H-BEA and various bimetallics including Pt plus Pd, Ni, Cu or Ga have been examined for n-hexane hydroisomerization The monometallic catalysts show similar activities and isomer selectivities as the bimetallic PtPd catalyst, but in presence of sulphur, the bimetallic catalyst is more resistant to poisoning Blomsma et al. have investigated the hydroconversion of n-heptane on catalysts containing Pt and Pd on H-BEA and USY zeolites and found that bimolecular reactions are suppressed and the hydrogenolysis activity eliminated hence the performance of hydroisomerization is greatly improved. These authors attribute these beneficial effects to better intimacy and balance of the metal/acid functions. 

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