本文選題：二次生長法　切入點：NaY沸石膜　出處：《太原理工大學》2017年碩士論文　論文類型：學位論文

【摘要】：NaY沸石膜有效孔徑為0.74 nm,具有較強的親水性和極性,適用于大分子物質的分離或者一些性質相似但存在極性差異體系的分離。碳酸二甲酯(DMC)作為一種綠色環(huán)保的化工產品,在工業(yè)生產中DMC是以甲醇(MeOH)作為原料進行合成的,在反應之后通常存在MeOH和DMC的共沸物,傳統(tǒng)分離工藝難以將其分離。MeOH分子動力學直徑小于DMC,而且其親水性和極性均高于DMC。因此,用NaY沸石膜通過滲透蒸發(fā)技術分離MeOH/DMC體系時,能夠優(yōu)先吸附MeOH。本論文詳細研究了晶種類型及尺寸、載體表面性質和分散介質組成及性質對晶種層質量及成膜的影響,并進一步探討了恒溫和變溫晶化對NaY沸石膜微結構的影響。通過透射電子顯微鏡(TEM)、掃描電子顯微鏡(SEM)、X-射線衍射儀(XRD)等手段對所合成的沸石晶種、載體、晶種層及制備的NaY沸石膜進行了分析表征,并對沸石膜進行了滲透蒸發(fā)分離性能的檢測,結果表明:1、晶種尺寸影響晶種層的質量,晶種粒徑過小,團聚嚴重;晶種粒徑過大,擔載不均勻,有載體裸露。以500 600 nm的小粒徑NaY沸石為晶種時,可完全鋪滿載體。2、載體的表面性質對晶種層的擔載及成膜有一定影響,以α-Al_2O_3和多孔不銹鋼為載體時,晶種均可以完全鋪滿載體;其中多孔不銹鋼制備的晶種層更為平整,但合成的沸石膜,由于與載體結合力差,存在局部脫落現(xiàn)象。3、以水為單一分散介質,晶種能完全鋪滿載體,晶種層比無水乙醇作單一分散介質更加平整;而以0.6 wt%的聚二烯二甲基氯化銨溶液(PDDA)作混合分散介質時,晶種可以非常平整的鋪滿載體,無任何載體裸露,合成的沸石膜也完整致密。4、以小粒徑NaY沸石為晶種,以0.6wt%的PDDA水溶液為混合分散介質,在α-Al_2O_3載體上制備高質量晶種層,經(jīng)100℃恒溫晶化7 h,可合成出致密連續(xù)的NaY沸石膜;而經(jīng)過變溫晶化(140℃2 h→100℃6 h)合成出的沸石膜,較恒溫晶化膜層更薄,但致密性不如前者。5、將100℃恒溫晶化7 h的NaY沸石膜在50℃條件下滲透分離MeOH/DMC體系,隨著原料液中甲醇濃度的增大(20 80 wt%),總滲透通量增加(0.648 0.796 Kg/(m~2·h)),分離因子降低(24.52 3.24);隨著原料液溫度的升高(20 70℃),總滲透通量增大(0.278 1.224 Kg/(m~2·h)),分離因子降低(23.52 2.78)。
[Abstract]:The effective pore size of NaY zeolite membrane is 0.74 nm, which has strong hydrophilicity and polarity. It is suitable for the separation of macromolecular substances or some systems with similar properties but different polarity. Dimethyl carbonate (DMC) is a green and environmentally friendly chemical product. In industrial production, DMC is synthesized from methanol MeOH. After the reaction, there are azeotropic compounds of MeOH and DMC. It is difficult for the traditional separation process to separate. MeOH molecular dynamic diameter is smaller than that of DMC, and its hydrophilicity and polarity are higher than that of DMC.Therefore, when NaY zeolite membrane is used to separate MeOH/DMC system by osmotic evaporation, In this paper, the effects of seed type and size, surface properties of carrier, composition and properties of dispersing medium on the quality and film formation of seed layer were studied in detail. The effect of constant temperature and variable temperature crystallization on the microstructure of NaY zeolite membrane was further discussed. The crystal seed and carrier of the synthesized zeolite were obtained by means of transmission electron microscope (TEM) and scanning electron microscope (SEM). The seed layer and NaY zeolite membrane were analyzed and characterized, and the pervaporation separation performance of zeolite membrane was tested. The results showed that the size of seed affected the quality of seed layer, the particle size of seed was too small, the agglomeration was serious, and the particle size of seed was too large. When the small diameter NaY zeolites with a diameter of 500 ~ 600nm are used as seed seeds, the carrier. 2. The surface properties of the carrier have a certain effect on the loading and film formation of the seed layer. When 偽 -Al _ 2O _ 2O _ 3 and porous stainless steel are used as the carrier, the surface properties of the carrier have a certain effect on the loading and film formation of the seed layer, when 偽 -Al _ 2O _ 2O _ 3 and porous stainless steel are used as carriers, The seed layer prepared by porous stainless steel is more smooth, but the synthesized zeolite membrane, due to its poor adhesion with the carrier, has the phenomenon of partial shedding. With water as the single dispersing medium, the seed can be completely covered with the carrier. The seed layer is more smooth than anhydrous ethanol as a single dispersing medium, and when the mixture medium is 0.6 wt% polydiene dimethylammonium chloride (PDDA), the seed can be very flat and covered with the carrier without any naked carrier. The synthesized zeolite membrane is also compact and compact. Using small diameter NaY zeolite as seed and 0.6 wt% PDDA aqueous solution as mixed dispersion medium, high quality seed layer is prepared on 偽 -Al _ 2O _ 3 carrier. After crystallization at 100 鈩，

本文編號：1579956