Vanadium poisoning of cracking catalysts: mechanism of poisoning and design of vanadium tolerant catalyst system
The mechanism of vanadium poisoning of cracking catalysts is described. Experimental results identify the poison precursor as volatile vanadic acid, H/sub 3/VO/sub 4/ which is formed under FCC regenerator conditions by the reaction V/sub 2/O/sub 5/(s) + 3H/sub 2/O(v) in equilibrium 2H/sub 3/VO/sub 4/(v). The concentration of H/sub 3/VO/sub 4/ in a typical regenerator (730/sup 0/C, 20% H/sub 2/O, 2 atm total pressure) is 1-10 ppm. Since H/sub 3/VO/sub 4/ is a strong acid analogous to H/sub 3/PO/sub 4/, it can destroy the zeolite by hydrolysis of the zeolites SiO/sub 2//Al/sub 2/O/sub 3/ framework. A basic solid with reasonable pore structure should be an effective scavenger. Basic alkaline earth oxides such as MgO or CaO are shown to be effective for vanadium scavenging. Microactivity testing shows excellent activity retention when 20% MgO is blended with cracking catalyst at vanadium loadings of 0.67% and 1.34% V by weight on catalyst. However, the SO/sub x/ in the regenerator flue gas can form a sulfate that competes with the formation of the vanadate. The degree of competition will be thermodynamically controlled. Since the formation of the vanadate from the oxide expands the lattice, pore structure effects exist similar to those observed for the reaction of calcium oxide with sulfur oxides.
- Research Organization:
- W.R. Grace and Co., Columbia, MD
- OSTI ID:
- 5559264
- Journal Information:
- J. Catal.; (United States), Journal Name: J. Catal.; (United States) Vol. 100:1; ISSN JCTLA
- Country of Publication:
- United States
- Language:
- English
Similar Records
Tin passivation of vanadium in metal-contaminated fluid-cracking catalysts: Electron paramagnetic resonance studies
The mechanism of zeolite Y destruction by steam in the presence of vanadium
Related Subjects
020400* -- Petroleum-- Processing
ALKALINE EARTH METAL COMPOUNDS
CALCIUM COMPOUNDS
CALCIUM OXIDES
CATALYSTS
CATALYTIC CRACKING
CHALCOGENIDES
CHEMICAL REACTIONS
CRACKING
DATA
DECOMPOSITION
DESIGN
ELEMENTS
EXPERIMENTAL DATA
HYDROLYSIS
INFORMATION
INORGANIC ION EXCHANGERS
ION EXCHANGE MATERIALS
LYSIS
MAGNESIUM COMPOUNDS
MAGNESIUM OXIDES
MATERIALS
METALS
MINERALS
NUMERICAL DATA
OXIDES
OXYGEN COMPOUNDS
PH VALUE
POISONING
POROSITY
PYROLYSIS
REMOVAL
SOLVOLYSIS
SULFUR COMPOUNDS
SULFUR OXIDES
THERMOCHEMICAL PROCESSES
THERMODYNAMICS
TRANSITION ELEMENTS
VANADIUM
ZEOLITES