本文選題：分子篩 + Silicalite-1��； 參考：《太原理工大學(xué)》2017年碩士論文

【摘要】：分子篩是一類由四面體初級結(jié)構(gòu)構(gòu)成的具有規(guī)則孔道結(jié)構(gòu)的籠型無機(jī)材料,因其具有有序規(guī)則的孔結(jié)構(gòu)、酸堿性位、較高的水熱穩(wěn)定性以及廉價(jià)易生產(chǎn)等特性,被廣泛應(yīng)用于催化、吸附、分離、離子交換和主客體組裝等化工領(lǐng)域。MFI型分子篩屬于分子篩中應(yīng)用最廣泛的一類,近些年的研究表明,其不含鋁的純硅分子篩Silicalite-1對CH_4、N_2、O2、CO_2、C_2H_6等小分子氣體具有很好的吸附效果,對于CH_4/N_2混合氣的吸附選擇性高于大多數(shù)普通吸附劑。隨著工業(yè)生產(chǎn)要求的提高以及科學(xué)的發(fā)展,對于分子篩的改性手段越來越多,其中多級孔結(jié)構(gòu)的分子篩是很重要的一種。多級孔分子篩的出現(xiàn),解決了困擾催化多年的積碳、積大分子、催化劑效率低、擴(kuò)散阻力大等問題。然而多級孔分子篩卻一直沒有在吸附分離領(lǐng)域得到應(yīng)用,最主要的原因是,相比于微孔結(jié)構(gòu),多級孔結(jié)構(gòu)表面積降低、微孔減少,這些直接導(dǎo)致多級孔分子篩對氣體的吸附量和吸附選擇性降低,這完全違背了一個吸附劑該有的特點(diǎn),因此多級孔結(jié)構(gòu)在吸附分離上的研究很少,并且也很少有研究者試圖去尋找或者合成一種既不會影響吸附量和吸附選擇性又可以體現(xiàn)多級孔結(jié)構(gòu)作用的分子篩材料�；谝陨蟽牲c(diǎn),本文探索了以晶種法快速合成多級孔Silicalite-1分子篩和微孔Silicalite-1分子篩的方法,并利用XRD、SEM、TEM、77K氮?dú)馕降缺碚鞣治鍪侄螌悠返奈锵�、形貌、孔結(jié)構(gòu)進(jìn)行了分析,然后對多級孔Silicalite-1分子篩和微孔Silicalite-1分子篩分別進(jìn)行了CH_4/N_2/CO_2/C_2H_6的吸附分離測試,研究多級孔結(jié)構(gòu)在吸附分離中的作用以及驗(yàn)證本文合成出的多級孔silicalite-1分子篩是否既不會影響吸附量和吸附選擇性又能體現(xiàn)多級孔結(jié)構(gòu)性能。主要研究內(nèi)容和結(jié)論有以下幾方面:第一,在熱水條件下,以硅溶膠為硅源,探索以晶種法快速合成silicalite-1分子篩,改變其中關(guān)鍵反應(yīng)物的添加量,最終得產(chǎn)生微孔silicalite-1的最佳反應(yīng)物比例為1:0.1:0.1:0.15:50的二氧化硅/乙胺/四丙基溴化銨(tpabr)/氫氧化鈉/蒸餾水以及質(zhì)量百分?jǐn)?shù)為10%sio2的晶種(二氧化硅來自于硅溶膠),合成介孔silicalite-1的最佳反應(yīng)物比例只需在微孔的基礎(chǔ)上加入0.3的氟化鉀,兩種孔型silicalite-1的反應(yīng)溫度和反應(yīng)時間均為453k和20小時。與常規(guī)合成方法相比,該方法大大縮短了反應(yīng)時間。基于得到的兩種孔型silicalite-1,分別對其進(jìn)行ch4、n2、co2、c2h6四種氣體的單氣吸附測試,測試結(jié)果為微孔silicalite-1具有較大的ch4、n2、co2、c2h6吸附量和較高的ch4/n2、co2/n2、co2/ch4、c2h6/ch4吸附選擇性,雖然介孔silicalite-1的各氣體吸附量較低一些,但是其對co2/ch4、co2/n2、c2h6/ch4的吸附選擇性有所提高,對ch4/n2的吸附選擇性與微孔silicalite-1的基本一致。第二,基于探索得的快速合成silicalite-1的方法,改變硅源,得以氣相二氧化硅為硅源的微孔和多級孔silicalite-1分子篩,不同于以硅溶膠為硅源的微孔和介孔silicalite-1分子篩的是,氣相二氧化硅得到的微孔silicalite-1和多級孔silicalite-1的表面積基本相同,并且兩者對ch4、n2、co2、c2h6的吸附量以及對ch4/n2、co2/ch4、co2/n2、c2h6/ch4的吸附選擇性也相同�；谝陨戏治�,分別對兩者進(jìn)行ch4/n2、co2/ch4、co2/n2、c2h6/ch4四組混合氣的穿透分離實(shí)驗(yàn),結(jié)果表明,多級孔Silicalite-1的穿透時間均短于微孔的,并且多級孔Silicalite-1和微孔Silicalite-1對于CH_4/N_2、C_2H_6/CH_4的保留時間是一樣的。進(jìn)一步得出結(jié)論,當(dāng)混合氣中分子動力學(xué)直徑較小的氣體分子為弱吸附質(zhì)、分子動力學(xué)直徑較大的氣體分子為強(qiáng)吸附質(zhì)(穿透實(shí)驗(yàn)中弱吸附質(zhì)先穿透出來,強(qiáng)吸附質(zhì)后穿透出來),用多級孔Silicalite-1分離它們的時候,穿透時間變短并且保留時間不變,與微孔Silicalite-1相比,縮短了變壓吸附循環(huán)時間,提高了變壓吸附效率,達(dá)到了更好的分離效果。
[Abstract]:Molecular sieve is a kind of cage type inorganic material with regular pore structure consisting of the primary structure of tetrahedron. Because of its orderly and regular pore structure, acid base position, high hydrothermal stability and low cost and easy production, it is widely used in the chemical fields of.MFI type, such as catalysis, adsorption, separation, ion exchange and host and guest assembly. Sieves are one of the most widely used types of molecular sieves. In recent years, it has been shown that the pure silicon molecular sieve Silicalite-1 without aluminum has a good adsorption effect on small molecular gases such as CH_4, N_2, O2, CO_2, C_2H_6 and so on. The adsorption selectivity for CH_4/N_2 mixture is higher than that of most ordinary adsorbents. There are more and more methods for molecular sieve modification, among which multistage porous molecular sieves are very important. The emergence of multilevel porous molecular sieves has solved the problems of carbon deposition, large molecules, low catalyst efficiency and large diffusion resistance, which have plagued the catalysis for many years. However, multistage molecular sieves have not been obtained in the field of adsorption separation. The main reason is that, compared to the microporous structure, the surface area of the multistage pore structure is reduced and the micropores are reduced, which directly lead to the reduction of the adsorption and adsorption of gas, which is completely contrary to the characteristics of an adsorbent. Therefore, there are few studies on the adsorption and separation of the multistage pore structure, and there are few of them. The researchers are trying to find or synthesize a molecular sieve material that does not affect the adsorption capacity and the adsorption selectivity and can reflect the multilevel pore structure. Based on the above two points, the rapid synthesis of multistage porous Silicalite-1 molecular sieves and microporous Silicalite-1 sub sieves by crystal seed method and the use of XRD, SEM, TEM, 77K nitrogen gas are explored. The phase, morphology and pore structure of the samples were analyzed by means of adsorption and other characterization methods. Then the adsorption separation and separation of multistage Silicalite-1 molecular sieves and microporous Silicalite-1 molecular sieves were carried out respectively. The role of multistage pore structure in the adsorption separation and the verification of the multistage hole silicali in this paper were verified. The main research contents and conclusions are as follows: first, the rapid synthesis of silicalite-1 molecular sieves using silica sol as the silicon source under hot water conditions is to make a rapid synthesis of the key reactants by using the silica sol as the silicon source, and the final production of the TE-1 molecular sieve has to be produced. The optimum reactant ratio of hole silicalite-1 is 1:0.1:0.1:0.15:50, silica / ethylamine / four propyl ammonium bromide (TPABr) / sodium hydroxide / distilled water and the mass percentage of 10%sio2 (silica from silica sol). The optimum reactant ratio for mesoporous silicalite-1 is only to add 0.3 potassium fluoride on the basis of micropores. The reaction temperature and reaction time of the two pass silicalite-1 are both 453k and 20 hours. Compared with the conventional synthesis method, the method greatly shortens the reaction time. Based on the obtained two kinds of pore type silicalite-1, the single gas adsorption tests of four kinds of gas, CH4, N2, CO2, C2H6, are carried out respectively. The test result is that the microporous silicalite-1 has a larger ch. 4, N2, CO2, C2H6 adsorption capacity and higher ch4/n2, co2/n2, co2/ch4, c2h6/ch4 adsorption selectivity, although the adsorption capacity of mesoporous silicalite-1 is lower, but its adsorption selectivity to co2/ch4, co2/n2, c2h6/ch4 is improved, and the adsorption selectivity for ch4/n2 is basically consistent with that of micropores. Second, based on the exploration fast The method of synthesizing silicalite-1 is to change the silicon source, the microporous and multistage pore silicalite-1 molecular sieves of silicon dioxide as the silicon source, different from the microporous and mesoporous silicalite-1 molecular sieves with silicon sol as the silicon source, and the surface area of the microporous silicalite-1 and the multistage pore silicalite-1 obtained by the gas phase silica is basically the same, and both of them have the same surface area. The adsorption capacity of CH4, N2, CO2, C2H6 and the adsorption selectivity for ch4/n2, co2/ch4, co2/n2, c2h6/ch4 are also the same. Based on the above analysis, the penetration separation experiments of the four groups of ch4/n2, co2/ch4, co2/n2 and c2h6/ch4 are carried out respectively. The results show that the penetration time of the multistage holes is shorter than that of the micropores, and the multistage holes are used. The retention time of CH_4/N_2 and C_2H_6/CH_4 is the same as the microporous Silicalite-1. Further conclusion is that when the gas molecules with smaller molecular dynamics diameter in the mixture are weak adsorbate, the molecular dynamics of the gas molecules with larger diameter are strong adsorbate (penetrating the weak adsorbate in the penetration experiment, and penetrating after the strong adsorbate). When they are separated with multistage holes Silicalite-1, the penetration time is shorter and the retention time is constant. Compared with the microporous Silicalite-1, the pressure swing adsorption cycle time is shortened, the pressure swing adsorption efficiency is improved, and the better separation effect is achieved.

【學(xué)位授予單位】：太原理工大學(xué)
【學(xué)位級別】：碩士
【學(xué)位授予年份】：2017
【分類號】：TQ424.25

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