以粉煤灰為鋁源納米級ZSM-5分子篩的合成調(diào)控
發(fā)布時間：2019-05-22 21:41
【摘要】：粉煤灰是煤炭在燃燒與轉(zhuǎn)化過程中產(chǎn)生的固體廢棄物,粉煤灰的大量排放與堆積不僅占用土地面積、污染環(huán)境而且危害人體健康。粉煤灰中有70%以上為SiO_2與Al2O_3,與分子篩的主要成分相似,故以粉煤灰為原料合成分子篩不僅能提高其資源利用價值、降低分子篩的合成成本,而且在一定程度上減少了環(huán)境污染,符合我國循環(huán)經(jīng)濟(jì)發(fā)展的戰(zhàn)略需求。本論文以固體廢棄物粉煤灰為原料,經(jīng)過焙燒、活化、除雜等步驟提取其中Al(OH)_3作為合成ZSM-5分子篩的鋁源,以正硅酸乙酯(TEOS)為硅源,以四丙基氫氧化銨(TPAOH)為模板劑,通過水熱合成法制備納米級ZSM-5分子篩。優(yōu)化了ZSM-5分子篩水熱合成體系的工藝參數(shù)(硅鋁比、晶化溫度、晶化時間、水硅比),考察了有機(jī)空間位阻劑對ZSM-5分子篩合成過程的影響,利用對Ni~(2+)的吸附能力評價分子篩的離子吸附性能與再生,初步探究了分子篩的吸附機(jī)理。并考察了不同晶化溫度、水硅比、有機(jī)添加劑條件下ZSM-5分子篩晶體生長動力學(xué)規(guī)律,建立分子篩晶化生長動力學(xué)模型。從宏觀和微觀的角度對ZSM-5分子篩的合成進(jìn)行調(diào)控,采用XRD、SEM、FT-IR、TGA、BET和PSD對ZSM-5分子篩產(chǎn)品進(jìn)行表征分析,研究結(jié)果如下:(1)粉煤灰中加入活化助劑(Na_2SiO_3),高溫焙燒后可以打破粉煤灰中較為穩(wěn)定的玻璃相和莫來石結(jié)構(gòu),轉(zhuǎn)化為易溶于酸的霞石,進(jìn)而提高了粉煤灰的化學(xué)活性,提高了粉煤灰的轉(zhuǎn)化利用率。粉煤灰經(jīng)焙燒后在鹽酸中浸漬,可成功提取其中的鋁元素,調(diào)解溶液pH值,可去除溶液中的Fe~(2+)、Ca~(2+)、Mg~(2+),得到較為純凈的Al(OH)_3,其提取率為80.89%。(2)以從粉煤灰中提取的Al(OH)_3作為鋁源,以TEOS為硅源,以TPAOH為模板劑,水熱合成法合成納米級ZSM-5分子篩的最佳工藝參數(shù)為:原料摩爾質(zhì)量比為n(H2O):n(SiO_2):n(TPAOH):n(Al(OH)_3)=2400:40:12:1,晶化溫度為140°C,晶化時間為6 h。(3)適量有機(jī)添加劑的添加可以有效調(diào)控分子篩晶粒大小、提高分子篩的產(chǎn)量,還可以增加分子篩比表面積,其中PVP的加入效果最好。(4)ZSM-5分子篩的生長動力學(xué)曲線為典型的“S”型曲線。其晶化過程有四個階段:誘導(dǎo)期、成核期、快速生長期、緩慢生長期。溫度是分子篩晶化動力學(xué)的主要動力學(xué)因素,隨著溫度的升高,分子篩成核期縮短,晶體的成核及生長速度增加。ZSM-5分子篩的成核表觀活化能En=24.18 kJ·mol-1及生長表觀活化能Eg=10.19 kJ·mol-1。;水硅比是影響水熱反應(yīng)體系堿性的主要因素,過高過低的水硅比均不利于分子篩的晶化,其中適宜的摩爾質(zhì)量比為:n(H2O):n(SiO_2)=60;有機(jī)添加劑尤其是PVP的加入可以提高分子篩的晶化生長速度,縮短成核期,使分子篩分散度有所提高,晶型更加完整。(5)有機(jī)添加劑可以提高分子篩的吸附性能,其中添加PVP制備的ZSM-5分子篩吸附性能最好,30°C、60 min時Ni~(2+)的最大去除率可達(dá)到92.8%。0.01 mol/L的EDTA-2Na作為再生助劑時,在40°C再生30 min時ZSM-5分子篩再生吸附能力最好,可達(dá)90.9%。ZSM-5分子篩對Ni~(2+)的吸附過程更符合Lagergren準(zhǔn)二級動力學(xué)方程,且PVP的加入,使ZSM-5分子篩吸附Ni~(2+)的能力提高。
[Abstract]:The fly ash is the solid waste produced in the process of combustion and conversion of the coal, and a great deal of discharge and accumulation of the fly ash not only occupy the area of the land, pollute the environment but also endanger the health of the human body. The fly ash has more than 70% of SiO2 and Al2O _ 3, and is similar to the main component of the molecular sieve, so that the molecular sieve is synthesized by using the fly ash as a raw material, not only can the resource utilization value of the molecular sieve be improved, the synthesis cost of the molecular sieve is reduced, and the environmental pollution is reduced to a certain extent, It is in accordance with the strategic demand of China's circular economy development. In this paper, Al (OH) _ 3 is taken as an aluminum source for synthesis of ZSM-5 molecular sieve, and tetrapropyl hydroxide (TPAOH) is used as a template agent by using solid waste fly ash as a raw material, and the Al (OH) _ 3 is used as an aluminum source for synthesizing a ZSM-5 molecular sieve through the steps of roasting, activation, impurity removal and the like, And the nano-scale ZSM-5 molecular sieve is prepared by a hydrothermal synthesis method. The process parameters (silicon-to-aluminum ratio, crystallization temperature, crystallization time and water-to-silicon ratio) of the ZSM-5 molecular sieve hydrothermal synthesis system were optimized, and the influence of the organic space-resistance agent on the synthesis process of the ZSM-5 molecular sieve was studied. The adsorption capacity of Ni ~ (2 +) was used to evaluate the ion adsorption performance and regeneration of the molecular sieve. The adsorption mechanism of molecular sieve was studied. The growth kinetics of ZSM-5 molecular sieve under different crystallization temperature, water-to-silicon ratio and organic additive were investigated. The synthesis of ZSM-5 molecular sieve was controlled by the macro and micro angle. The results of XRD, SEM, FT-IR, TGA, BET and PSD were used to characterize the ZSM-5 molecular sieve. The results were as follows: (1) The activation aid (Na _ 2SiO _ 3) was added to the fly ash. The stable glass phase and the mullite structure in the fly ash can be broken after the high-temperature roasting, so that the nepheline which is easily soluble in the acid is converted, so that the chemical activity of the fly ash is improved, and the conversion utilization rate of the fly ash is improved. After the fly ash is roasted in hydrochloric acid, the aluminum element can be extracted successfully, the pH value of the solution can be adjusted, and the Fe ~ (2 +), Ca ~ (2 +) and Mg ~ (2 +) in the solution can be removed to obtain the pure Al (OH) _ 3, and the extraction rate is 80.89%. (2) Al (OH) _ 3 extracted from fly ash is used as an aluminum source, TEOS is used as a silicon source, and TPAOH is used as a template agent, and the hydrothermal synthesis method is used for synthesizing the nano-scale ZSM-5 molecular sieve with the best technological parameters as follows: the molar mass ratio of the raw materials is n (H2O): n (SiO2): n (TPAOH): n (Al (OH)3) = 2400:40:12:1, and the crystallization temperature is 140 DEG C, The crystallization time is 6 h. (3) the addition of the appropriate amount of organic additive can effectively control the size of the crystal grain of the molecular sieve, improve the yield of the molecular sieve, and also increase the specific surface area of the molecular sieve, wherein the addition effect of the PVP is the best. (4) The growth kinetics curve of the ZSM-5 molecular sieve is a typical "S"-type curve. The crystallization process has four stages: the induction period, the nucleation period, the rapid growth phase and the slow growing period. The temperature is the main dynamic factor of the crystallization kinetics of the molecular sieve, and with the increase of the temperature, the nucleation period of the molecular sieve is shortened, and the nucleation and growth rate of the crystal are increased. The apparent activation energy (En = 24.18 kJ 路 mol-1) and the apparent activation energy (Eg = 10.19 kJ 路 mol-1) of the ZSM-5 molecular sieve. and the water-to-silicon ratio is the main factor which influences the alkalinity of the hydrothermal reaction system, and the water-to-silicon ratio is not good for the crystallization of the molecular sieve, wherein the appropriate molar mass ratio is: n (H2O): n (SiO2) = 60; the addition of the organic additive, in particular the PVP, can improve the crystallization and growth speed of the molecular sieve and shorten the nuclear phase, The dispersity of the molecular sieve is improved, and the crystal form is more complete. and (5) the organic additive can improve the adsorption performance of the molecular sieve, wherein the adsorption performance of the ZSM-5 molecular sieve prepared by the addition of the PVP is the best, the maximum removal rate of the Ni-(2 +) can reach 92.8% and the EDTA-2Na of 0.01 mol/ L can be used as the regeneration assistant when the adsorption performance of the ZSM-5 molecular sieve prepared by adding the PVP is the best; The adsorption capacity of the ZSM-5 molecular sieve can reach 90.9% at 40 擄 C for 30min. The adsorption process of the ZSM-5 molecular sieve to Ni ~ (2 +) is more in line with the Lagergren's quasi-second-order kinetic equation, and the addition of PVP increases the ability of the ZSM-5 molecular sieve to adsorb Ni ~ (2 +).
【學(xué)位授予單位】：東北石油大學(xué)
【學(xué)位級別】：碩士
【學(xué)位授予年份】：2017
【分類號】：TQ424.25;TB383.1
本文編號：2483287
[Abstract]:The fly ash is the solid waste produced in the process of combustion and conversion of the coal, and a great deal of discharge and accumulation of the fly ash not only occupy the area of the land, pollute the environment but also endanger the health of the human body. The fly ash has more than 70% of SiO2 and Al2O _ 3, and is similar to the main component of the molecular sieve, so that the molecular sieve is synthesized by using the fly ash as a raw material, not only can the resource utilization value of the molecular sieve be improved, the synthesis cost of the molecular sieve is reduced, and the environmental pollution is reduced to a certain extent, It is in accordance with the strategic demand of China's circular economy development. In this paper, Al (OH) _ 3 is taken as an aluminum source for synthesis of ZSM-5 molecular sieve, and tetrapropyl hydroxide (TPAOH) is used as a template agent by using solid waste fly ash as a raw material, and the Al (OH) _ 3 is used as an aluminum source for synthesizing a ZSM-5 molecular sieve through the steps of roasting, activation, impurity removal and the like, And the nano-scale ZSM-5 molecular sieve is prepared by a hydrothermal synthesis method. The process parameters (silicon-to-aluminum ratio, crystallization temperature, crystallization time and water-to-silicon ratio) of the ZSM-5 molecular sieve hydrothermal synthesis system were optimized, and the influence of the organic space-resistance agent on the synthesis process of the ZSM-5 molecular sieve was studied. The adsorption capacity of Ni ~ (2 +) was used to evaluate the ion adsorption performance and regeneration of the molecular sieve. The adsorption mechanism of molecular sieve was studied. The growth kinetics of ZSM-5 molecular sieve under different crystallization temperature, water-to-silicon ratio and organic additive were investigated. The synthesis of ZSM-5 molecular sieve was controlled by the macro and micro angle. The results of XRD, SEM, FT-IR, TGA, BET and PSD were used to characterize the ZSM-5 molecular sieve. The results were as follows: (1) The activation aid (Na _ 2SiO _ 3) was added to the fly ash. The stable glass phase and the mullite structure in the fly ash can be broken after the high-temperature roasting, so that the nepheline which is easily soluble in the acid is converted, so that the chemical activity of the fly ash is improved, and the conversion utilization rate of the fly ash is improved. After the fly ash is roasted in hydrochloric acid, the aluminum element can be extracted successfully, the pH value of the solution can be adjusted, and the Fe ~ (2 +), Ca ~ (2 +) and Mg ~ (2 +) in the solution can be removed to obtain the pure Al (OH) _ 3, and the extraction rate is 80.89%. (2) Al (OH) _ 3 extracted from fly ash is used as an aluminum source, TEOS is used as a silicon source, and TPAOH is used as a template agent, and the hydrothermal synthesis method is used for synthesizing the nano-scale ZSM-5 molecular sieve with the best technological parameters as follows: the molar mass ratio of the raw materials is n (H2O): n (SiO2): n (TPAOH): n (Al (OH)3) = 2400:40:12:1, and the crystallization temperature is 140 DEG C, The crystallization time is 6 h. (3) the addition of the appropriate amount of organic additive can effectively control the size of the crystal grain of the molecular sieve, improve the yield of the molecular sieve, and also increase the specific surface area of the molecular sieve, wherein the addition effect of the PVP is the best. (4) The growth kinetics curve of the ZSM-5 molecular sieve is a typical "S"-type curve. The crystallization process has four stages: the induction period, the nucleation period, the rapid growth phase and the slow growing period. The temperature is the main dynamic factor of the crystallization kinetics of the molecular sieve, and with the increase of the temperature, the nucleation period of the molecular sieve is shortened, and the nucleation and growth rate of the crystal are increased. The apparent activation energy (En = 24.18 kJ 路 mol-1) and the apparent activation energy (Eg = 10.19 kJ 路 mol-1) of the ZSM-5 molecular sieve. and the water-to-silicon ratio is the main factor which influences the alkalinity of the hydrothermal reaction system, and the water-to-silicon ratio is not good for the crystallization of the molecular sieve, wherein the appropriate molar mass ratio is: n (H2O): n (SiO2) = 60; the addition of the organic additive, in particular the PVP, can improve the crystallization and growth speed of the molecular sieve and shorten the nuclear phase, The dispersity of the molecular sieve is improved, and the crystal form is more complete. and (5) the organic additive can improve the adsorption performance of the molecular sieve, wherein the adsorption performance of the ZSM-5 molecular sieve prepared by the addition of the PVP is the best, the maximum removal rate of the Ni-(2 +) can reach 92.8% and the EDTA-2Na of 0.01 mol/ L can be used as the regeneration assistant when the adsorption performance of the ZSM-5 molecular sieve prepared by adding the PVP is the best; The adsorption capacity of the ZSM-5 molecular sieve can reach 90.9% at 40 擄 C for 30min. The adsorption process of the ZSM-5 molecular sieve to Ni ~ (2 +) is more in line with the Lagergren's quasi-second-order kinetic equation, and the addition of PVP increases the ability of the ZSM-5 molecular sieve to adsorb Ni ~ (2 +).
【學(xué)位授予單位】：東北石油大學(xué)
【學(xué)位級別】：碩士
【學(xué)位授予年份】：2017
【分類號】：TQ424.25;TB383.1
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