Comparison of Pt/KL catalysts prepared by ion exchange or incipient wetness impregnation
- Northwestern Univ., Evanston, IL (United States)
Pt/KL catalysts prepared by ion exchange (IE), incipient wetness impregnation (IWI), and coimpregnation with KCl(IWI + KCl) have been characterized by dynamic techniques, chemisorption of H[sub 2] and CO. Fourier transform-infrared spectroscopy (FT-IR) of adsorbed CO, and catalytic tests using n-hexane (n-C6) and methylcyclopentane (MCP) conversions as probe reactions. Temperature-programmed reduction (TPR) shows significant differences between the IE and IWI catalysts. After calcination up to 400 C, the IWI samples contain Pt[sup 4+] ions that are reduced at 250 C, but IE samples contain PtO particles that are reduced at 11 C, besides two Pt[sup 2+] species with TPR peaks at 80 and 150 C. High resolution electron microscopy, adsorption, FT-IR, and catalytic results consistently show that, after reduction, the IWI catalysts contain smaller Pt particles located inside the zeolite channels, while the IE sample has larger particles, some of which are on the external surface. At high temperature, excess KCl reacts with zeolite protons, forming HCL which escapes. In comparison to the IE samples, the IWI catalysts are less acidic, less active for n-C[sub 6] conversion, more selective for dehydrocyclization, but less selective for hydrogenolysis, and they deactivate less. Since hydrogenolysis requires large Pt ensembles, the small Pt particles in the IWI catalysts produce less C[sub 1]-C[sub 5] compounds and less coke. The product distribution of MCP ring opening shows higher than statistical selectivity toward 3-methylpentane, suggesting that the MCP molecule becomes oriented inside the zeolite channels.
- DOE Contract Number:
- FG02-87ER13654
- OSTI ID:
- 6975910
- Journal Information:
- Journal of Catalysis; (United States), Vol. 133:2; ISSN 0021-9517
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
ORGANIC
PHYSICAL AND ANALYTICAL CHEMISTRY
02 PETROLEUM
CATALYSTS
CHEMICAL PREPARATION
CYCLOALKANES
CATALYTIC REFORMING
HEXANE
PLATINUM
CATALYTIC EFFECTS
ABSORPTION SPECTROSCOPY
CALCINATION
CARBON MONOXIDE
CHEMISORPTION
COKING
COMPARATIVE EVALUATIONS
DEACTIVATION
DEHYDROCYCLIZATION
DEHYDROGENATION
ELECTRON MICROSCOPY
FOURIER TRANSFORMATION
HYDROGEN
IMPREGNATION
INFRARED RADIATION
ION EXCHANGE
PARTICLE SIZE
PLATINUM OXIDES
POTASSIUM CHLORIDES
REDUCTION
TEMPERATURE CONTROL
ZEOLITES
ALKALI METAL COMPOUNDS
ALKANES
CARBON COMPOUNDS
CARBON OXIDES
CARBONIZATION
CHALCOGENIDES
CHEMICAL REACTIONS
CHLORIDES
CHLORINE COMPOUNDS
CONTROL
DECOMPOSITION
ELECTROMAGNETIC RADIATION
ELEMENTS
EVALUATION
HALIDES
HALOGEN COMPOUNDS
HYDROCARBONS
INORGANIC ION EXCHANGERS
INTEGRAL TRANSFORMATIONS
ION EXCHANGE MATERIALS
MATERIALS
METALS
MICROSCOPY
MINERALS
NONMETALS
ORGANIC COMPOUNDS
OXIDES
OXYGEN COMPOUNDS
PLATINUM COMPOUNDS
PLATINUM METALS
POTASSIUM COMPOUNDS
PYROLYSIS
RADIATIONS
REFORMER PROCESSES
SEPARATION PROCESSES
SILICATE MINERALS
SIZE
SORPTION
SPECTROSCOPY
SYNTHESIS
THERMOCHEMICAL PROCESSES
TRANSFORMATIONS
TRANSITION ELEMENT COMPOUNDS
TRANSITION ELEMENTS
400201* - Chemical & Physicochemical Properties
020400 - Petroleum- Processing