A dual-membrane airlift reactor for cyclohexanone ammoximation over titanium silicalite-1

A novel dual-membrane airlift reactor with a ceramic outer-membrane as a reactant ammonia distributor and another ceramic inner-membrane as a catalyst separator was developed for the cyclohexanone ammoximation over titanium silicalite-1(TS-1) without the addition of extra solvent such as tert-butanol, resulting in no need of separation step for solvent. It was interesting to find that the introduction of membrane distribution could increase the selectivity of cyclohexanone oxime by 18%, because many tiny ammonia bubbles could be produced with a membrane distributor to strengthen the mix of gas phase and organic phase. A blowing process was introduced into the membrane reactor to overcome the membrane fouling and decrease the filtration resistance. The operation conditions were optimized, and the conversion and selectivity remained stable at about 87% and 76% in a 25 h continuous run, respectively. Our research verifies the advantages of a dual-membrane reactor in a continuous ammoximation.