Synthesis And Performance Study Of Separation Materials Used For Enrichment Of Biomass Conversion Products-biobutanol And Furfural From Water

With the rapid development of economy,energy crisis and environmental degradation are highlighted.Development and valorization of renewable biomass resources can efficiently tackle the above mentioned problems.Biobutanol and furfural are two important energy and chemical products of biomass conversion.However,the low content of 1-butanol or furfural in aqueous solution during biomass fermentation or hydrolysis process requires the enrichment through separation methods.Compared with the traditional distillation method,adsorption and pervaporation methods have relatively simple,low energy consumption and environmental friendly.However,separation materials with high selectivity,high eefficiency play a leading role in separation process.Based on microporous materials as adsorbent and membranes materials having the hydrophobic features,these have advantages in the low content of butanol or furfural separation in aqueous solution.The paper carried out high-silica zeolites and zeolitic imidazolate frameworks(ZIFs)materials as research object and discussed the relationship between the structure and adsorption performance in biobutanol and furfural adsorption from aqueous solution.Secondly,good separation performance of adsorption materials(MAF-6)combined with polymer materials to prepare organic/inorganic hybrid membranes to study biobutanol and furfural pervaporation performance from aqueous solution.The main research contents and conclusions are as follows:(1)We synthesize 10-ring 3D channels of ZSM-5,12-ring 1D channels of ZSM-12 and 12-ring 3D channels of Beta and the relationship between the structure and adsorption performance were studied by static adsorption isotherm,static adsorption kinetic and fixed-bed dynamic breakthrough curves.The experimental results showed the 1-butanol adsorption amount is Beta(0.12 g/g)> ZSM-5(0.116 g/g)> ZSM-12(0.07 g/g)due to 12-ring 3D of Beta with largest pore volume;Equilibrium time of zeolites was short(10 min).This is because its aperature is bigger than dynamic diameter of 1-butanol(5.0 ?)and zeolites are channel sturcture.Breakthrough time of Beta(45 min)is longer ZSM-5(38 min)and ZSM-12(25 min),which is due to 12-ring 3D Beta with largest pore volume at flow rate of 0.2 mL/min,bed height of 20 cm.The adsorptive separation mechanism of three high-silica zeolites with channel structure is thermodynamic separations.The adsorptive separation performance of Beta zeolites was the best out of all the zeolites samples tested.However,due to lower specific surface area and pore volume,the total adsorption capacity of zeolites is not high.(2)Compared with high-silica zeolites,zeolitic imidazolate frameworks(ZIFs)(6-ring cages ZIF-8,8-ring cages MAF-6 and 12-ring channel TIF-1 Zn)with larger pore volume were synthesized and adsorption separation performance was studied from static adsorption isotherms,adsorption kinetic and fixed-bed dynamic breakthrough curves.From adsorption isotherm perspective,the adsorption amount of ZIF-8 and MAF-6 with cages structure is larger TIF-1 Zn with channel structure,but adsorption amount is higher than zeolites obviously.From adsorption kinetic perspective,the three hydrophobic ZIFs exhibited different adsorption kinetics of 1-butanol,following the order TIF-1 Zn(15 min)< MAF-6(30 min)< ZIF-8(60 min)but the adsorption equilibrium time of MAF-6 and ZIF-8 is shorter than zeolites due to MAF-6 and ZIF-8 with cages structure and smaller aperture.In breakthrough experiments,at flow rate of 0.2 mL/min,bed height of 20 cm.ZIF-8 and MAF-6 were shown to achieve separation by a combination of thermodynamic and kinetics effects.The breakthrough times of ZIF-8 and MAF-6 are longer than that of TIF-1 Zn due to larger pore volume and cage structures of ZIF-8 and MAF-6.The adsorptive separation mechanism of TIF-1 Zn is based on thermodynamic effects.(3)Due to MAF-6 having excellent separation performance in separation ABE aqueous solution,PEBA 2533 particles were directly dissolved MAF-6 suspension without drying procedure to effective overcome the nanoparticle agglomerations to prepare MAF-6/PEBA mixed matrix membrane.The pervaporation performance of the prepared MAF-6/PEBA mixed matrix mmebrane with various MAF-6 loading,temperatures and concentration for separating furfural from its aqueous solution were investigated.The pervaporation performance of MAF-6/PEBA mixed matrix membranes was studied for model ABE(Acetone-Butanol-Ethanol)fermentation broth.Compared with other ABE pervaporation membranes,the MAF-6/PEBA mixed matrix membrane with 20 wt.% loading show high total of 2889 g/(m2·h)and 1-butanol separation factor of 25.7 at 60 °C in model ABE(1:2:0.5 wt.%)solution and exhibited the excellent comprehensive performance.(4)The hydrophobic MAF-6 with excellent separation performance was carried out to study adsorptive separation performance of furfural from aqueous solution according to adsorption and pervaporation methods.Firstly,static adsorption and fixed-bed dynamic breakthrough behaviour were studied using MAF-6 with large-pore hydrophobic from furfural/water system.The experiment results showed that the adsorption amount of MAF-6 is 0.26 g/g;equilibrium time of MAF-6 is 45 min and breakthrough time is 100 min.Secondly,large-pore nanodisperse MAF-6/PEBA mixed matrix membranes were employed for efficient recovery of furfural via pervaporation.The experimental results showed that permeation flux and separation factor all increased with increasing MAF-6 loading amount,which overcome ?trade-off? effect.Compared with other furfural pervaporation membranes,the MAF-6/PEBA mixed matrix membranes showed the highest total flux(3203 g/(m2·h))and a separation factor of 52 referred to a 2 wt.% furfural aqueous solution at 70 °C and exhibited the excellent comprehensive performance.The structure and performance of MAF-6/PEBA mixed matrix membrane exhibited a good stability during pervaporation test for 80 h.The transfer mechanism in MAF-6/PEBA mixed matrix membrane during furfural-permselective pervaporation process was investigated.The research results showed that total flux increase and separation factor decrease with MAF-6 loading increasing.This indicated that the pore aperture of MAF-6 was considered as furfural-permselective paths.