N-interstitial Re cluster

EXAFS analysis for the sample after the fifth pulse reaction of benzene and O2 revealed the formation of Re monomers with Re=0 bonds (CN = 3.7 0.2) at 0.173 O.OOlnm and Re-O bond (CN = 1.3 0.6) at 0.211 0.002nm (Table 10.7). The monomeric structure (vi) in Table 10.7 was similar to that after the steady state reaction (i). The Re monomers (vi) were transformed into the Rejo clusters again by NH3 treatment for 2h. NH3 has two roles, N supplier and reduc-tant, in producing the catalytically active N-interstitial Re cluster, which converts benzene and O2 into phenol with a selectivity of 93.9%, accompanied with oxidation of the cluster to the inactive Re monomer (Scheme 10.4). Thus, the formation of the N-interstitial Rejo clusters and the decomposition of the Rejo clusters to the Re monomers are balanced under the steady-state reaction conditions [73]. 

Molecular oxygen was the active oxidant for the phenol synthesis and the maximum phenol selectivity (93.9%) was achieved on the N-interstitial Re cluster supported on HZSM-5. Molecular oxygen was activated in the space between the two Re6 octahedral cores of the Re10 cluster and benzene concertedly reacted on the activated 02 with the very low activation energy of 24 kj mol-1. The pore size of HZSM-5 is 5.5 A, which is similar to the size of the Re6-octahedral cluster framework,... 

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See also in sourсe #XX -- [ ]

See also in sourсe #XX -- [ ]

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