Crossflow filtration of nanosized catalysts suspension using ceramic membranes

Ceramic membranes were used to separate nanosized nickel catalysts from slurry in hydrogenation of p-nitrophenol to p-aminophenol. Experimental results have revealed that the tubular ceramic membranes are capable of removing nickel catalysts with an efficiency of 100% and have no adverse impacts on the performance of catalysts. The analysis of fouling resistance in membrane filtration showed that cake layer formation on membrane surface was the main fouling mechanism. The unexpected phenomenon in cake resistance was considered to arise from the size and fractal properties of the nickel particle aggregates. A combined pore blockage and cake filtration model was utilized to describe the time-dependent flux decline. The model results agreed well with those obtained experimentally. A suitable membrane with optimized pore size which gives the highest steady flux was determined based on the model prediction. The cleaning of a fouled membrane can be achieved by use of strong acidic solutions.