Efficient recovery of ultrafine catalysts from oil/water/solid three-phase system by ceramic microfiltration membrane

A submerged ceramic membrane filtration system was constructed for the filtration of oil/water/solid three-phase mixture, where hexane acted as the oil phase and beta zeolite as the solid phase. The effects of the phase composition and transmembrane pressure on the filtration performance of ceramic membrane were investigated. The liquid composition in the feed and transmembrane pressure greatly affected the filtration rate and the proportion of oil/water in the permeate. Only aqueous phase passed through the membrane at lower pressures, both water and oil phases could permeate through the membrane with a lower water yield at higher pressures, and the lower water content in the feed promoted the earlier discharge of oil. The hydrophilic nature of ceramic membrane should be responsible for the filtration behavior. A combined process applying low pressure for water permeation and high pressure for oil permeation was proposed for the filtration of oil/water/solid three-phase mixture, and an efficient separation of oil/water/solid three phases was achieved.