Catalysis of hydrocarbon conversion over zeolite-supported platinum-rhenium bimetallic clusters
The existence of mixed PtRe clusters in Y-zeolites is manifested from the high hydrogenolysis activity leading to methane exhibited by bimetallic catalysts compared to monometallic catalysts when converting n-heptane or cyclopentane. For instance, the turnover frequency of methane formation from cyclopentane hydrogenolysis over a PtRe/NaY catalysts at 240 C and 1 atm, is 187 times higher than the average value of those over Pt/NaY and Re/NaY. PtRe/Y-zeolite catalysts prepared from Re{sub 2} (CO){sub 10}, NaReO{sub 4}, or (Re(NH{sub 2}C{sub 2}H{sub 4}NH{sub 2}){sub 2}O{sub 2})Cl, all contain significant amounts of bimetallic clusters that can be detected by hydrocarbon hydrogenolysis reactions. Deposition of Re{sub 2} (CO){sub 10} onto Pt/NaY is a more promising way to prepare bimetallic zeolites than the other two methods used. The mobility of Re species is indispensable for the formation of mixed PtRe clusters on catalyst supports. Migration of Re oxide species in calcined samples is not confined within a zeolite particle. Interparticle migration of Re oxide can be inferred from the observation that bimetallic clusters are detected via the probe reactions in a physical mixture of Pr/NaHY and Re/NaHY. Presulfided PtRe/NaY exhibits superior activity maintenance to presulfided Pt/NaY, which is reminiscent of alumina-supported catalysts used in naphtha reforming. This result agrees with a model which assumes that the sulfur atoms strongly adsorbed on the Re atoms of mixed PtRe ensembles impose geometrical hindrance on the growth of harmful graphitic entities.
- Research Organization:
- Northwestern Univ., Evanston, IL (USA)
- OSTI ID:
- 7172081
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
020400* -- Petroleum-- Processing
ALKANES
ALLOYS
BIMETALS
CATALYST SUPPORTS
CATALYTIC EFFECTS
CATALYTIC REFORMING
CHALCOGENIDES
CHEMICAL PREPARATION
CHEMICAL REACTIONS
CYCLOALKANES
DEHYDROGENATION
DEPOSITION
ELEMENTS
HEPTANE
HYDROCARBONS
IMPREGNATION
INORGANIC ION EXCHANGERS
ION EXCHANGE
ION EXCHANGE MATERIALS
MATERIALS
METALS
METHANE
MINERALS
ORGANIC COMPOUNDS
OXIDES
OXYGEN COMPOUNDS
PERFORMANCE TESTING
PLATINUM
PLATINUM METALS
REFORMER PROCESSES
REFRACTORY METAL COMPOUNDS
RHENIUM
RHENIUM COMPOUNDS
RHENIUM OXIDES
SODIUM ALLOYS
SULFIDATION
SURFACE PROPERTIES
SYNTHESIS
TESTING
TRANSITION ELEMENT COMPOUNDS
TRANSITION ELEMENTS
YTTRIUM
YTTRIUM ALLOYS
ZEOLITES