A system combining nanocatalytic reaction with crossflow ultrafiltration (UF) was used to prepare p-aminophenol from p-nitrophenol. In this system, nanosized nickel catalysts in suspension were employed during reaction, and then separated from slurry by an UF membrane filter. The adhesion of nickel particles to contact surfaces caused a rapid decline in the hydrogenation rate and UF flux. In order to understand the effect of materials properties, and operating parameters on adhesion of catalysts, the nickel adhesion was investigated by measuring the mass of nickel remaining on solid surfaces after contact. Surface materials with different roughness and hydrophilicity have been tested, such as poly(tetrafluoroethylene) (PTFE), stainless steel (AISI 304) and glass. The results show that rougher surfaces have more adhesion than smooth ones. Hydrophilic glass has less adhesion than hydrophobic PTFE, while intermediately hydrophilic stainless steel has the most adhesion due to its surface magnetic effect. During ultrafiltration, adhesion decreases with increasing crossflow velocity and increases with increasing suspension concentration. With the addition of microsized alumina particles in suspension, the adhesion of nanosized nickel can be inhibited effectively. (c) 2007 American Institute of Chemical Engineers.