EVALUATION OF CATALYSTS FOR SELECTIVE HYDROCRACKING OF POLYPHENYLS

Technical Report · Thu Apr 25 04:00:00 EST 1963

OSTI ID:4695327

Gardner, L E

Metal-promoted aluminas of low surface area and free from acidity were found to be the best catalysts for selectively hydrocracking the carbon-carbon bond between phenyl rings in polyphenyls in an extensive screening program carried out on biphenyl, o-, and m-terphenyls as model charge stocks. With cobalt molybdate or nickel oxide (1.3%) on gamma alumina of 25 to 100 sq m/gram surface area, conversions of 60 to 95% were obtained with 60 to 80% selectivity for the desired chain-splitting reaction. Vanadia-cobalt oxide or piatinum on this alumina base were also found to be active and selective for this reaction. Hydrocracking was carried out at temperatures from 800 to 1000 deg F and pressures from 500 to 1000 psig. The feed was ordinarily a 10 to 50 wt% solution in xylene and was pumped over the catalyst at from 0.5 to 2.0 liquid volumes per hour with 10 to 50 moles of hydrogen per mole of polyphenyl circulated with it. With these simple model compounds it was possible, primarily by gas-solid chromatographic columns, to characterize completely the cracked products obtained. Alkyl biphenyls or alkyl benzenes, from terphenyl or biphenyl feedstock respectively, were the principal by-products found, resulting from the competing reactions of hydrogenation, ring cleavage, and polymerization. Coke formation was low, normally about 0.5% of the feed in a two-hour run. Dual function catalysts, which actually promote both ring hydrogenation and cracking were found to be unsatisfactory. High yields of undesired low molecular weight products and alkyl polyphenyls resulted. Catalysts on silica or silica-alumina, or acid treated samples all displayed too much cracking activity and coke formation. Total conversion appeared to be independent of catalyst surface area, but selectivity was greatly improve and coke yield reduced as surface area was decreased down to 25 sq. m/gram. Using the selective catalysts, reclamation of high boiling polyphenyl polymers resulting from radiolysis of terphenyls in the core of a nuclear reactor will be studied. Successful conversion of a major portion of this waste to usable coolant can be an important factor in reducing the costs of the use of terphenyl as a coolantmoderator in a power reactor. (auth)

• Research Organization: Phillips Petroleum Co. Research and Development Dept., Bartlesville, Okla.
• NSA Number: NSA-17-028434
• OSTI ID: 4695327
• Report Number(s): IDO-16858
• Country of Publication: United States
• Language: English

Related Subjects

ACIDITY
ALKYL RADICALS
ALUMINUM
BENZENE
BOILING
CARBON
CATALYSIS
CHEMICAL REACTIONS
COBALT OXIDES
ECONOMICS
HYDROGEN
HYDROGENATION
HYDROLYSIS
LIQUIDS
MOLYBDENUM OXIDES
NICKEL OXIDES
ORGANIC COOLANT
ORGANIC MODERATOR
PLATINUM
POLYMERIZATION
POLYPHENYLS
POWER PLANTS
PRESSURE
RADIATION CHEMISTRY
REACTOR CORE
REACTOR TECHNOLOGY
RESIDUES
SILICON
SOLUTIONS
SURFACES
TEMPERATURE
VANADIUM OXIDES
XYLENE