Acid Resistance And Catalytic Performance Of High Alumina ZSM-5 Zeolite Membrane

Chemical plants,chemical fiber plants,metal surface treatmentand electroplating industries discharge a large number of inorganic acids wastewater every year in China and industrial acidic wastewater must be post-treated and achieve the national discharge being discharge.Membrane separation technology has the advantages of high efficiency,energy conservation,environmental protection,molecular level separation,simple and easy control,which has a broad application prospect in the treatment of acidic wastewater.In addition,plenty of glycerol are produced in the field of biofuels,converting biomass polyols into oxygen-containing high-value compounds is an important research topic.High aluminum ZSM-5 zeolite membranes have excellent hydrophilicity,acid resistance,and abundant of strong Bronsted acid sites,which have potential application values in the fields of industrial acid wastewater separation and catalytic glycerol conversion.Therefore,the research content of this article is as follows:（1）Pervaporation performance of high alumina ZSM-5 zeolite membrane in inorganic acid and salt solution.In this study,the high alumina ZSM-5 zeolite membrane（Si O₂/Al₂O₃=9）was applied to separate inorganic acid and salt solution system（sulfate and phosphate system）by pervaporation,dehydration and desalination performance of the membrane for the inorganic acid and salt solution are investigated in this work.ZSM-5 zeolite membrane was continuously concentrated 3wt%sulfuric acid solution,the concentration was increased to 20 wt%after 44 h,and the membrane kept a long-term stability for 20 wt%sulfuric acid solution.No matter the ternary or pentanary H₂SO₄/sulfate or H₃PO₄/phosphate mixture(2M H₂SO₄/1g·L^-1 sulfate or 2M H₂SO₄/1g·L^-1 phosphate),only water molecules can permeate the membrane,the p H value of the permeation is 7 and the desalination rate reaches 100%.Besides,the advanced characterization results show that the high-alumina ZSM-5 zeolite membrane still maintains the integrity of structure and morphology for separation of high-concentration inorganic acids and salts,the high-alumina ZSM-5 zeolite membrane has good acid resistance,hydrophilicity and stability.（2）Glycerol aldehyde was prepared by catalytic oxidation of glycerol with high alumina ZSM-5 zeolite membrane.Strong Bronsted acid sites of the high aluminum ZSM-5 zeolite membrane are utilized to convert glycerol into aldehydes,ketones,acids,and other organic substances,improving the economic value of the product.Influences of membrane,reaction temperature,and the membrane area to feed mass ratio of ZSM-5 zeolite membranes on the oxidation of glycerol to glyceraldehyde were investigated in this study.When the molar ratio of glycerol to hydrogen peroxide in the reaction solution,the reaction temperature,and the membrane area to feed mass ratio of ZSM-5 molecular sieve membranes are 1:1,50℃,and 0.18,the permeation flux,the selectivity and content of glycerol on the permeation side were 0.55 kg·m^-2·h^-1,100%,and 7.93%,respectively.X-ray diffraction patterns,scanning electron microscopy images,gas chromatography results,and synchronous analysis suggested that integrity of the structure,morphology,and strong Bronsted acid sites of the ZSM-5 zeolite membrane were still maintained after the reaction.In this study,high aluminum ZSM-5 zeolite membrane are applied to achieve the green oxidation of glycerol under low temperature.