Preparation Of Metallic Based Zeolite Membranes Structured Catalytic Materials

Structured catalysts,which are uni-body structures composed of interconnected cells or channel,are widely used in environmental applications and pollution control because of low pressure drop,high gas fluxes and negligible concent ration and/or temperature gradients,and increasingly in many new reactors application such as chemical and refining process,catalytic combustion,and high exothermic/endothermic reaction coupling reaction.As a structured catalyst,zeolite membrane catalyst play a role in separation and reaction. It not only can reduce the energy consumption and the operation steps,but also result higher conversion and reaction selectivity than in the thermodynamic equilibrium conversion rate. Combinated by chemical bond,zeolite cann't detached from the carrier.Compared with traditional pellet or granular catalysts,zeolite membrane catalyst possess many advantages,such as low pressure drop and negligible concent ration and/or temperature gradients.Besides,it has its own unique shape selecting catalysis and high temperature resistance,and therefore the activity and selectivity of the catalyst greatly enhanced.Firstly,ZSM-5 zeolite membranes were synthesized on stainless steel using TPAOH as SDA.Effects of the crystallization conditions,such as pH values of the synthesis solution and contents of H₂O of the synthsis solution,had been investigated.The optimized conditions were crystalling at 175℃for 24-36 hours and with mole ratios TEOS:Al₂O₃:TPAOH:H₂O=1: 0.01:0.16:110.B-oriented Silicalite-1 zeolite films were synthesized on stainless steel using TPAOH as SDA.ZSM-5 zeolite membranes were synthesized on stainless steel which was supported b-oriented Silicalite-1 zeolite films transition layer.ZSM-5 zeolite membranes which were synthesized on stainless steel which was supported b-oriented Silicalite-1 zeolite films are more performance than stainless steel by in situ synthesis,and had no cracks in the baking process. B-oriented Silicalite-1 zeolite films transition Layer was beneficial to synthesize ZSM-5 zeolite membranes which are good adhesion.By using coating technique with nano seeds,Silicalite-1 zeolite membranes on stainless steel substrate were prepared through hydrothermal treatment from clear solution.By electrochemical deposition,embedding nano-Cu particles onto the surface of seed coating layer and Silicalite-1 zeolite membranes were studied.The prepared seeds,seed coating layer, Silicalite-1 membranes and the composition of the surface material were characterized by SEM, XRD and EDX.The results showed that pure uniform Silicalite-1 seeds were about 200 nm. The uniform and smooth seed layer was formed on the stainless steel substrate surface by coating with the coating suspension.By electrochemical deposition,nano-Cu particles were embedded in the crystal interspace of seed coating layer.A dense and free defect Silicalite-1 zeolite membrane was obtained on the seeded support by the following hydrothermal treatment from clear solution,nano-Cu particles could not be embedded into the surface of hydrothermal-synthesised Silicalite-1 zeolite membranes by electrochemical deposition.