Surface organometallic chemistry on metals applied to the environment: Hydrogenolysis of AsPh3 with nickel supported on alumina

The reaction of AsPh3 with Ni/Al2O3 at 100 to 200 degreesC under 6 to 30 ba rs of hydrogen has been followed by kinetic analysis of both the consumptio n of AsPh3 and the evolution of benzene and cyclohexane as well as magnetic and XRD measurements of the metallic and intermetallic phase(s). The react ion proceeds via complete hydrogenolysis of the As-Ph bonds, with final for mation of a well-characterized NiAs alloy (XRD). The mechanism of alloy for mation is complex: at low coverage of the nickel surface, stepwise hydrogen olysis of the As-Ph bonds leads to the formation of the surface organometal lic fragments Ni-s[AsPhx](y) (kinetic studies and analytical data). Further hydrogenolysis of these fragments progressively leads to the formation of arsenic "adatoms" which quickly migrate inside the nickel particles to form NiAs0.45 amorphous intermetallic phases (XRD and magnetic measurements). T he reaction then proceeds slowly up to the As/Ni ratio of unity with format ion of the crystalline NiAs "nickeline" phase (XRD). (C) 2001 Academic Pres s.