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Two series of catalysts with nickel oxide or molybdenum oxide as the active component and with different zeolites as supports were prepared by incipient wetness impregnation method, and their structural properties and acidity were characterized by means of XRD, H2-TPR, N2 adsorption and desorption, FTIR spectrum of adsorbed pyridine and NH3-TPD. The catalytic activity of the prepared materials was investigated for the hydrodealkylation of commercial C9 + heavy aromatics to BTX. The results show that the catalytic performance is greatly influenced by the specific surface area, the acidity and the interaction between zeolite and metal oxide, and little affected by the pore diameter of catalysts. For NiO catalysts, the samples with the moderate interaction between zeolite and NiO exhibit the relatively high selectivity of BTX. And for MoO3 catalysts, the presence of the molybdenum species associated with Brønsted acid site causes the remarkable reduction of selectivity. The presence of Brønsted acid sites, the growth of the strength of Lewis acid sites and the increase of acid amount and the specific surface area can all enhance the conversion of C9 + aromatics. Finally, compared with other zeolites, the HMCM-56 catalysts show the excellent overall catalytic performance with the yield of BTX more than 60 mol%, whether using NiO or MoO3 as the active component. [ABSTRACT FROM AUTHOR]

The pressure drop of a cross-flow moving-bed was investigated in a two-dimensional rectangular apparatus. The effects of the particle velocity, the superficial gas velocity, the formation and development of cavity/raceway and voidage of particles on the pressure drop were investigated experimentally under the operational conditions of 0.09–1.35 m/s of the superficial gas velocity and 0.95–9.68 cm/min of the particle velocity. The experimental results show that the particle velocity has little influence on the pressure drop, while the phenomena of cavity and pinning occur when the cross-flow velocity is high enough. The development of a cavity or a raceway can result in three types of variations of pressure drop with time: stabilization, slight fluctuation and severe fluctuation. A cavity appears in a process cycle of ‘formation-growing up-collapsing-fluidization’ at a high gas velocity. On the basis of experimental results, a model for calculating the pressure drop after a cavity occurs and a dimensionless relationship of cavity size is developed, which gives a good qualitative account of the experimental data. [ABSTRACT FROM AUTHOR]