Modifiers in rhodium catalysts for carbon monoxide hydrogenation: Structure-activity relationships
More efficient manufacture of oxygenates from syngas can fulfill a vital need for additives to transportation fuels. To achieve this, a much better understanding of the factors that control catalytic syngas reactions is needed, especially those that produce oxygenates rather than hydrocarbons. Some of the multi-functional systems used here are not only a better catalyst for oxygenates, but also provide an excellent system to investigate the effect of modifiers on the reaction pathways. Catalytic hydrogenation of carbon monoxide on supported rhodium catalysts gives rise to a variety of products such as hydrocarbons, alcohols, aldehydes, acids, esters and ethers. The effect of metal precursor, the support, and the nature and the amount of modifier on the rates and selectivity to these products is studied. Sodium and molybdenum modified Rh/Al{sub 2}O{sub 3} catalysts are investigated in detail. Also a new method of kinetic analysis, the delplot method, was developed and used. The delplot method sorts products according to their rank, finds the number and location of slow steps in a reaction network and separates regimes of conversion where product rank changes. Catalysts were also investigated using a battery of characterization techniques such as chemisorption, FTIR, XRD, XPS, TEM/EDX, TPD, ISS, ESR and solid-state NMR. Results from kinetics, characterization and test reaction studies are consistent with a dual-site mechanism where carbon monoxide is activated by Rh and hydrogen is activated by MoO{sub 3-x}. Increased activity and selectivity is attributed to a more effective hydrogenation capability provided by partially reduced molybdena. Addition of sodium to Rh/Al{sub 2}O{sub 3} decreases the rate of carbon monoxide hydrogenation substantially.
- Research Organization:
- Delaware Univ., Newark, DE (USA)
- OSTI ID:
- 5813278
- Resource Relation:
- Other Information: Thesis (Ph. D.)
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
10 SYNTHETIC FUELS
CARBON MONOXIDE
METHANATION
MOLYBDENUM
CATALYTIC EFFECTS
RHODIUM
SODIUM
ALUMINIUM OXIDES
CATALYSIS
CATALYST SUPPORTS
CHEMICAL ACTIVATION
CHEMICAL REACTION KINETICS
CHEMISORPTION
CRYSTAL STRUCTURE
DATA ANALYSIS
DESORPTION
ELECTRON SPIN RESONANCE
FOURIER TRANSFORMATION
FUEL ADDITIVES
HYDROGENATION
INFRARED SPECTRA
ION SCATTERING ANALYSIS
MOLYBDENUM OXIDES
NUCLEAR MAGNETIC RESONANCE
PHOTOELECTRON SPECTROSCOPY
SURFACE PROPERTIES
SYNTHESIS
SYNTHESIS GAS
TEMPERATURE CONTROL
TRANSMISSION ELECTRON MICROSCOPY
X-RAY DIFFRACTION
X-RAY SPECTROSCOPY
ADDITIVES
ALKALI METALS
ALUMINIUM COMPOUNDS
CARBON COMPOUNDS
CARBON OXIDES
CHALCOGENIDES
CHEMICAL ANALYSIS
CHEMICAL REACTIONS
COHERENT SCATTERING
CONTROL
DIFFRACTION
ELECTRON MICROSCOPY
ELECTRON SPECTROSCOPY
ELEMENTS
FLUIDS
GASES
INTEGRAL TRANSFORMATIONS
KINETICS
MAGNETIC RESONANCE
METALS
MICROSCOPY
MOLYBDENUM COMPOUNDS
NONDESTRUCTIVE ANALYSIS
OXIDES
OXYGEN COMPOUNDS
PLATINUM METALS
REACTION KINETICS
REFRACTORY METAL COMPOUNDS
RESONANCE
SCATTERING
SEPARATION PROCESSES
SORPTION
SPECTRA
SPECTROSCOPY
TRANSFORMATIONS
TRANSITION ELEMENT COMPOUNDS
TRANSITION ELEMENTS
010408* - Coal
Lignite
& Peat- C1 Processes- (1987-)
100200 - Synthetic Fuels- Production- (1990-)