Catalytic transformation of 5-hydroxymethylfurfural (HMF) to produce 2,5-dimethylfuran (DMF) was studied over bimetallic (PtIr) and monometallic (Pt) catalysts supported on CMK-3 and SBA-15 mesoporous materials. The optimum temperature and hydrogen pressure for the maximum production of DMF were 120 °C and 15 atm, respectively. Increases in temperature and pressure decreased the selectivity to DMF. The catalysts were broadly characterized by different techniques, such as XRD, N2-isotherms, XPS, TPR, TEM and NH3-TPD. It was found that the metallic particles were well reduced and highly dispersed on the surface ofsupports having large surface areas and narrow pore size distributions. The PtIr alloy species catalytic sites were very active and selective towards the formation of the desired DMF. PtIr-CMK-3 catalyst showed an excellent activity, selectivity and stability to be applied in this process.
Hydrogenation of six model feeds containing three-, two-, and one-ring aromatic compounds was investigated to gain insights into the aromatic hydrogenation reaction chemistry over a commercial NiMo catalyst under practical reaction conditions. The hydrogenation reactivity of the aromatic compounds followed the following order: phenanthrene ∼ two-ring aromatics . one-ring aromatic. Comparison with previous studies revealed that the relative reactivity of the aromatic compounds is strongly influenced by the nature of the catalyst. Multiple-component feed studies showed that phenanthrene and naphthalene strongly inhibited the tetralin hydrogenation rate; however, naphthalene and tetralin had no appreciable effect on phenanthrene conversion. Langmuir-Hinshelwood-type rate equations were used to describe the reaction kinetics with physically meaningful and well-identified parameter values. The inhibition was attributed to competitive adsorption and was described in the kinetic model by adsorption terms that were obtained from the multicomponent feed experiments.
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