Modifiers in rhodium catalysts for carbon monoxide hydrogenation: Structure-activity relationships

Thesis/Dissertation · Sun Jan 01 04:00:00 EST 1989

OSTI ID:5813278

Bhore, N A

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
• Country of Publication: United States
• Language: English

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ADDITIVES
ALKALI METALS
ALUMINIUM COMPOUNDS
ALUMINIUM OXIDES
CARBON COMPOUNDS
CARBON MONOXIDE
CARBON OXIDES
CATALYSIS
CATALYST SUPPORTS
CATALYTIC EFFECTS
CHALCOGENIDES
CHEMICAL ACTIVATION
CHEMICAL ANALYSIS
CHEMICAL REACTION KINETICS
CHEMICAL REACTIONS
CHEMISORPTION
COHERENT SCATTERING
CONTROL
CRYSTAL STRUCTURE
DATA ANALYSIS
DESORPTION
DIFFRACTION
ELECTRON MICROSCOPY
ELECTRON SPECTROSCOPY
ELECTRON SPIN RESONANCE
ELEMENTS
FLUIDS
FOURIER TRANSFORMATION
FUEL ADDITIVES
GASES
HYDROGENATION
INFRARED SPECTRA
INTEGRAL TRANSFORMATIONS
ION SCATTERING ANALYSIS
KINETICS
MAGNETIC RESONANCE
METALS
METHANATION
MICROSCOPY
MOLYBDENUM
MOLYBDENUM COMPOUNDS
MOLYBDENUM OXIDES
NONDESTRUCTIVE ANALYSIS
NUCLEAR MAGNETIC RESONANCE
OXIDES
OXYGEN COMPOUNDS
PHOTOELECTRON SPECTROSCOPY
PLATINUM METALS
REACTION KINETICS
REFRACTORY METAL COMPOUNDS
RESONANCE
RHODIUM
SCATTERING
SEPARATION PROCESSES
SODIUM
SORPTION
SPECTRA
SPECTROSCOPY
SURFACE PROPERTIES
SYNTHESIS
SYNTHESIS GAS
TEMPERATURE CONTROL
TRANSFORMATIONS
TRANSITION ELEMENT COMPOUNDS
TRANSITION ELEMENTS
TRANSMISSION ELECTRON MICROSCOPY
X-RAY DIFFRACTION
X-RAY SPECTROSCOPY