Effect of aminoguanidine (AG) on erythrocyte lipid peroxidation and actiwities of antioxidant enzymes in experimental diabetes

Abstract

Four catalysts, Co–Mo and Ni–Mo, designed to cover a widerange of activity for aromatic ring hydrogenation and twocatalysts, zeolite-Co–Mo, with different cracking activitieswere tested, in the hydrodesulfurization of dibenzothiophene(DBT) and 4,6-dimethyl-DBT (DMDBT) in a fixed-bed reactor at360°C and a hydrogen pressure of 5.4 MPa. Increasing thehydrogenation activity of the catalysts increased the moleratio, α, of cyclohexylbenzenes to biphenyls produced from bothreactants. Although α had little effect on thehydrodesulfurization (HDS) rate of DBT, the HDS rate of DMDBTincreased significantly with α, approching thesame level as forDBT at α = 2. Introduction of zeolite H-ZSM-5 to the Co–Mo–Alcatalyst increased the HDS rate of DBT at a lower value of α anddecreased that of DMDBT. No cracking reactions of DBT and DMDBTwere detected. A Co–Mo–Al catalyst containing HY zeolitedisplayed significant cracking activity of DMDBT defined by tworoutes: demethylation of benzenic rings and scission of the C–Cbond connecting the benzenic rings. It resulted in increasingHDS rates of DMDBT by about threefold relative to the Co–Mo–Alcatalyst, yielding toluene and benzene, at a ratio of about 3,as the main HDS products. About 80% of the DMDBT desulfurizedwith HY–Co–Mo–Al catalyst was converted through “cracking”intermediates, 90% of those intermediates being produced throughthe scission of the C–C bond connecting the benzenic rings.