Coke and product profiles formed along the catalyst bed during n-heptane reforming

Journal Article · Tue Jun 01 04:00:00 EDT 1993 · Journal of Catalysis; (United States)

DOI:https://doi.org/10.1006/jcat.1993.1149· OSTI ID:6216049

Querini, C A; Fung, S C ^[1]

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1. Exxon Research and Engineering Company, Annandale, NJ (United States)

Deactivation of Pt/Al[sub 2]O[sub 3] and Pt-Re/Al[sub 2]O[sub 3] during n-heptane reforming was studied using a multi-outlet reactor, which allows determination of gas-phase composition profiles and coke profiles along the catalyst bed. Coke profiles strongly depend on catalyst type and pressure. At low pressure, 105 kPa, the coke content on the Pt catalyst increases along the bed and at 1225 kPa decreases. Between these pressure values, a maximum in the coke profile is observed. Similar changes in C[sub 5] ring naphthene concentration profile with pressure are observed and a general correlation has been established between coke and C[sub 5] naphthenes covering variations in time on-oil, pressure, and location of catalysts. Therefore, C[sub 5] naphthenes appear as the dominant factor in the deactivation of these catalysts. The addition of Re to a Pt catalyst has a similar effect on the coke profile and on the C[sub 5] naphthene profile of the Pt catalyst as increasing its operation pressure, i.e., shifting the maximum of coke C[sub 5] naphthene profile from bed outlet to inlet. Additionally, pressure at which coke is deposited affects TPO spectra. An increase in the total pressure of a Pt catalyst produces a TPO spectrum similar to that of Pt-Re. These results suggest that Re increases the hydrogen surface concentration on Pt-Re, and therefore, Re decreases the dehydrogenating capacity of this catalyst and increases its hydrogenating activity. The lower dehydrogenation activity of Pt-Re catalysts as compared with Pt catalysts result in forming less C[sub 5] ring diolefins and, thus, Pt-Re catalysts exhibit lower coke make and better stability. 46 refs., 12 figs., 3 tabs.

• OSTI ID: 6216049
• Journal Information: Journal of Catalysis; (United States), Journal Name: Journal of Catalysis; (United States) Vol. 141:2; ISSN 0021-9517; ISSN JCTLA5
• Country of Publication: United States
• Language: English

Related Subjects

02 PETROLEUM
020400 -- Petroleum-- Processing
37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY
400201* -- Chemical & Physicochemical Properties
ALKANES
ALUMINIUM COMPOUNDS
ALUMINIUM OXIDES
CATALYSTS
CATALYTIC EFFECTS
CATALYTIC REFORMING
CHALCOGENIDES
CHEMICAL REACTIONS
COKE
DEACTIVATION
DEHYDROGENATION
ELEMENTS
HEPTANE
HYDROCARBONS
HYDROGEN
METALS
NONMETALS
ORGANIC COMPOUNDS
OXIDES
OXYGEN COMPOUNDS
PLATINUM
PLATINUM METALS
REFORMER PROCESSES
RHENIUM
STABILITY
TRANSITION ELEMENTS