Study And Application Of Coupling Nanocatalysis And Inorganic Membranes

Nano-sized catalysts have received considerable attention for their excellentcatalytic properties. Up to now, various methods have been developed to preparenano-sized catalysts, and furthermore, a lot of nano-sized catalysts have beencommercially produced. But the large scale applications of nano-sized catalysts havebeen still few, especially for these unsupported suspended nano-sized catalysts. Oneof the main reasons is due to the fact that the problem of recovery of nano-sizedcatalysts from product mixture has not been well resolved. High-gradient magneticseparation and inorganic membrane separation are two main methods for recoveringnano-sized catalysts and the latter is more practicable. Therefore, applying inorganicmembrane separation in nanocatalysis is important for implementing the industrialapplications of nano-sized catalysts.In recent years, inorganic membrane reactors have been paid many attentions,but the research has been focused on gas-phase applications. A limited number ofstudies are concerned with the applications of inorganic membrane reactors to liquidphase reactions, especially for liquid phase reactions with catalysts in suspension.In order to implement commercial applications of nano-sized catalysts, theresearch work was carried out on coupling of nanocatalysis and inorganic membranesin this dissertation: examining the catalytic properties of nano-sized nickel for thepreparation of p-aminophenol; theoretical analyzing side-stream nanocatalyticinorganic membrane reactor for the preparation of p-aminophenol over nano-sizednickel; designing a novel submerged inorganic membrane reactor to overcome theshortage of side-stream membrane reactor and to enhance the membrane flux byprocess intensification. These works will provide fundamental knowledge for theapplication of nanocatalytic inorganic membrane reactor.Firstly, catalytic properties of nano-sized nickel were investigated in the catalytichydrogenation of p-nitrophenol to p-aminophenol in comparison with conventionalRaney nickel, which is the commercially used catalyst. Experimental results showedthat the catalytic activity, stability and selectivity of nano-sized nickel were superiorto those of Raney nickel under the same reaction conditions. Particle size, surfacestructure and absence of micropores might be responsible for nano-sized nickel'sexcellent catalytic properties. Fresh nickel and used nickel samples were characterizedby particle size analyzer and nitrogen sorption. The results indicated that aggregation IV南 京 工 业 大 学 博 士 学 位 论 文of nanoparticles might lead to the deactivation of nano-sized nickel and jam ofmicropores could be the major reason for the deactivation of Raney nickel. Inconclusion, nano-sized nickel was an efficient catalyst for the catalytic hydrogenationof p-nitrophenol to p-aminophenol. The intrinsic kinetics of preparation ofp-aminophenol from p-nitrophenol over nano-sized nickel catalyst was also studiedunder exclusion from effects of external diffusion and internal diffusion. Experimentalresults showed that external diffusing influence could be eliminated when theagitation rate was over 300 rpm. Under the conditions that the reaction temperature,the hydrogen pressure, the initial concentration of p-nitrophenol were 80-110 C, 0.8 oMPa-1.9 MPa, 37.94-249.97 g·L-1 respectively, the reaction was zeroth order withrespect to p-nitrophenol and 1.3 order with respect to hydrogen, and the activationenergy of the reaction was 32.62 kJ·mol-1.Secondly, the feasibility of using cross-flow ultrafiltration technology to separatethe nano-sized nickel catalyst from a liquid was investigated. At the same time, effectsof operating conditions on the filtration performance were discussed. Other filtrationbehaviors, such as membrane fouling and cleaning, were also studied. Experimentalresults showed that the nano-sized nickel catalyst could be completely rejected by aceramic membrane with a mean pore size of...