Comparison of Pt/KL catalysts prepared by ion exchange or incipient wetness impregnation

Journal Article · Sat Feb 01 04:00:00 EST 1992 · Journal of Catalysis; (United States)

DOI:https://doi.org/10.1016/0021-9517(92)90245-D· OSTI ID:6975910

Ostgard, D J; Kustov, L; Poeppelmeier, K R; Sachtler, W M.H. ^[1]

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1. 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), Journal Name: Journal of Catalysis; (United States) Vol. 133:2; 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
ABSORPTION SPECTROSCOPY
ALKALI METAL COMPOUNDS
ALKANES
CALCINATION
CARBON COMPOUNDS
CARBON MONOXIDE
CARBON OXIDES
CARBONIZATION
CATALYSTS
CATALYTIC EFFECTS
CATALYTIC REFORMING
CHALCOGENIDES
CHEMICAL PREPARATION
CHEMICAL REACTIONS
CHEMISORPTION
CHLORIDES
CHLORINE COMPOUNDS
COKING
COMPARATIVE EVALUATIONS
CONTROL
CYCLOALKANES
DEACTIVATION
DECOMPOSITION
DEHYDROCYCLIZATION
DEHYDROGENATION
ELECTROMAGNETIC RADIATION
ELECTRON MICROSCOPY
ELEMENTS
EVALUATION
FOURIER TRANSFORMATION
HALIDES
HALOGEN COMPOUNDS
HEXANE
HYDROCARBONS
HYDROGEN
IMPREGNATION
INFRARED RADIATION
INORGANIC ION EXCHANGERS
INTEGRAL TRANSFORMATIONS
ION EXCHANGE
ION EXCHANGE MATERIALS
MATERIALS
METALS
MICROSCOPY
MINERALS
NONMETALS
ORGANIC COMPOUNDS
OXIDES
OXYGEN COMPOUNDS
PARTICLE SIZE
PLATINUM
PLATINUM COMPOUNDS
PLATINUM METALS
PLATINUM OXIDES
POTASSIUM CHLORIDES
POTASSIUM COMPOUNDS
PYROLYSIS
RADIATIONS
REDUCTION
REFORMER PROCESSES
SEPARATION PROCESSES
SILICATE MINERALS
SIZE
SORPTION
SPECTROSCOPY
SYNTHESIS
TEMPERATURE CONTROL
THERMOCHEMICAL PROCESSES
TRANSFORMATIONS
TRANSITION ELEMENT COMPOUNDS
TRANSITION ELEMENTS
ZEOLITES