燃煤固體廢物制備介孔硅基材料
發(fā)布時間：2018-07-25 17:15
【摘要】：粉煤灰和煤氣化渣是我國煤炭能源利用過程中產(chǎn)生的兩種典型燃煤固體廢物。我國所面臨的燃煤固體廢物的處理壓力十分巨大,既要消納歷史積壓而來的數(shù)量巨大的粉煤灰,又要為排放量日益增加的煤氣化渣尋找處置途徑。傳統(tǒng)的資源化消納途徑如建筑材料、農(nóng)用土壤等領(lǐng)域的市場已經(jīng)趨于飽和,且隨著這些領(lǐng)域原料價格的下滑和應(yīng)用標(biāo)準(zhǔn)的提升,燃煤固體廢物在其中已不占據(jù)優(yōu)勢。因此,燃煤固體廢物的資源化勢必向高附加值和創(chuàng)新型的應(yīng)用方向發(fā)展。本研究針對燃煤固體廢物的高硅特性,將其應(yīng)用到介孔硅基材料的制備上,從而借助介孔硅基材料廣泛的應(yīng)用范圍,將燃煤固體廢物的資源化提升到一個新的平臺,這對燃煤固體廢物的永續(xù)消納具有十分深刻的意義。本研究的內(nèi)容分為兩大部分。一部分是針對粉煤灰和煤氣化渣化學(xué)性質(zhì)的差異,分別通過不同的合成方法制備出介孔硅基材料。另一部分是對所獲取的介孔硅基材料熱穩(wěn)定性和應(yīng)用性能的檢測。在介孔硅基材料的合成中,通過對煤氣化渣的酸預(yù)處理和堿熔處理獲得了化學(xué)活性高的高硅原料,然后通過溶膠-凝膠工藝成功制備出具有超大比表面積(1347 m2/g)和較大孔容(0.83 cm3/g)的有序介孔硅基材料MCM-41。然而溶膠-凝膠工藝由于前驅(qū)體組分和均一性難以控制,在工業(yè)放大上存在困難。故在以粉煤灰為原料合成介孔硅基材料的過程中,本研究首次提出了化學(xué)酸溶蝕法制備介孔材料。針對酸溶蝕反應(yīng)強(qiáng)度與所獲得硅基材料比表面積間的關(guān)系,本研究提出了反應(yīng)強(qiáng)度數(shù)值模型,并借助此模型討論了酸溶蝕法的成孔過程和機(jī)制。隨模型定義的反應(yīng)強(qiáng)度值(RI)的升高,所獲得的硅基材料的孔結(jié)構(gòu)按以下順序發(fā)生變化：無孔、楔形介孔、平行板形介孔、圓筒形介孔、微孔和楔形介孔。在最佳反應(yīng)強(qiáng)度(RI=5327)下,所制備出的新型介孔硅基材料為圓筒形介孔結(jié)構(gòu),且具有大的比表面積(585.02m2/g)和孔容(0.54 cm3/g)。這證明了酸溶蝕法可以制備出與溶膠-凝膠法相媲美的介孔硅基材料,而酸溶蝕法所具備的工藝簡單,工業(yè)化難度低等特點(diǎn),將會給介孔材料的合成領(lǐng)域帶來變革。通過對溶膠-凝膠法和酸溶蝕法獲得的兩種介孔硅基材料熱穩(wěn)定性的對比發(fā)現(xiàn),后者的熱穩(wěn)定性要明顯優(yōu)于前者。在900℃下處理1h后,溶膠-凝膠法獲得的MCM-41的孔容僅剩余15%,而酸溶蝕法獲得的孔容還保留有55%。在介孔硅基材料于相變材料載體和重金屬吸附的應(yīng)用研究中,同時討論了孔形對應(yīng)用性能的影響。具有圓筒形介孔的硅基材料在作為相變材料載體時,其有效負(fù)載率(54.85%)最大,所獲得的定型相變材料相變熱為50.65 J/g,相變溫度為30.9℃在循環(huán)熱穩(wěn)定性和泄露性檢測中均表現(xiàn)優(yōu)越,具有極強(qiáng)的應(yīng)用價值。所合成的介孔硅基材料直接應(yīng)用于重金屬Cr和Pb吸附時,其吸附量較低。經(jīng)螯合基團(tuán)EDTA和DTPA改性后,圓筒形介孔硅基材料對Pb的吸附量大幅上升(17.30 mg/g和16.90 mg/g),成為三種孔形中的最佳選擇。改性后的介孔硅基材料在重金屬吸附領(lǐng)域具備很強(qiáng)的競爭力。
[Abstract]:Coal ash and coal gasification slag are two typical solid wastes produced in the process of coal energy utilization in China. The pressure of the treatment of solid waste in China is very huge. It is necessary to eliminate the huge amount of coal ash from the historical backlog, and to find the way to deal with the coal gasification slag. The market for source reduction, such as building materials, agricultural soil and other fields, has become saturated, and with the decline of the price of raw materials and the improvement of application standards, the coal solid waste has not taken advantage of it. Therefore, the resource of coal solid waste is bound to develop to high value-added and innovative application. In view of the high silicon characteristics of coal burning solid waste, it is applied to the preparation of mesoporous silica based materials. With the wide application range of mesoporous silica based materials, the resource of solid waste is promoted to a new platform, which is of ten profound significance to the sustainable consumption of solid waste. The content of this study is divided into two parts. Part. One part is the preparation of mesoporous silica based materials by different synthetic methods for the chemical properties of fly ash and coal gasification slag. The other part is to detect the thermal stability and application performance of the mesoporous silica based materials. In the synthesis of mesoporous silica, the acid pretreatment and alkali melt treatment of coal gasification slag have been passed. High silicon materials with high chemical activity were obtained, and the ordered mesoporous silica based materials with super specific surface area (1347 m2/g) and larger Kong Rong (0.83 cm3/g) were successfully prepared by sol-gel process. However, the sol-gel process was difficult to control in the industrial amplification due to the difficulty of controlling the precursor composition and homogeneity. In the process of synthesizing mesoporous silica based materials from raw materials, the mesoporous materials were prepared by chemical acid dissolution method for the first time. In view of the relationship between the strength of acid dissolution reaction and the specific surface area of the silicon base material obtained, a numerical model of the reaction strength was put forward in this study, and the pore forming process and mechanism of acid dissolution method were discussed with the model. The pore structure of the silicon based material is changed in the following order: no hole, wedge mesoporous, parallel plate mesoporous, cylindrical mesoporous, microporous and wedge-shaped mesoporous. Under the best reaction strength (RI=5327), the new mesoporous silicon-based material is a cylindrical mesoporous structure with large RI. Specific surface area (585.02m2/g) and Kong Rong (0.54 cm3/g). This proves that acid dissolution method can produce mesoporous silica based on sol-gel method. The acid dissolution process is simple, and the difficulty of industrialization will bring about changes in the synthesis field of mesoporous materials. The sol-gel method and acid dissolution method are obtained. The thermal stability of the two mesoporous silica based materials shows that the thermal stability of the latter is obviously superior to the former. After the treatment of 1H at 900 C, the pore volume of the MCM-41 obtained by the sol-gel method is only 15%, while the pore volume obtained by the acid dissolution method still holds 55%. in the application of mesoporous silica based materials for phase variable materials and the adsorption of heavy metals. At the same time, the influence of the pore shape on the application performance is discussed. The effective load rate (54.85%) of the silicon based material with a cylindrical mesoporous material is the largest when it is used as a phase change material carrier. The phase change heat of the fixed phase change material is 50.65 J/g, the phase change temperature is 30.9, and it has excellent performance in the cyclic thermal stability and leakage detection. The adsorption capacity of the mesoporous silica based materials synthesized directly on Cr and Pb adsorption is low. After the modification of chelating group EDTA and DTPA, the adsorption of cylindrical mesoporous silica based materials on Pb is greatly increased (17.30 mg/g and 16.90 mg/g), which is the best choice in the three pores. The modified mesoporous silica based materials are in heavy metals. The field of adsorption is very competitive.
【學(xué)位授予單位】：華東理工大學(xué)
【學(xué)位級別】：博士
【學(xué)位授予年份】：2016
【分類號】：TQ127.2;X705
本文編號：2144496
[Abstract]:Coal ash and coal gasification slag are two typical solid wastes produced in the process of coal energy utilization in China. The pressure of the treatment of solid waste in China is very huge. It is necessary to eliminate the huge amount of coal ash from the historical backlog, and to find the way to deal with the coal gasification slag. The market for source reduction, such as building materials, agricultural soil and other fields, has become saturated, and with the decline of the price of raw materials and the improvement of application standards, the coal solid waste has not taken advantage of it. Therefore, the resource of coal solid waste is bound to develop to high value-added and innovative application. In view of the high silicon characteristics of coal burning solid waste, it is applied to the preparation of mesoporous silica based materials. With the wide application range of mesoporous silica based materials, the resource of solid waste is promoted to a new platform, which is of ten profound significance to the sustainable consumption of solid waste. The content of this study is divided into two parts. Part. One part is the preparation of mesoporous silica based materials by different synthetic methods for the chemical properties of fly ash and coal gasification slag. The other part is to detect the thermal stability and application performance of the mesoporous silica based materials. In the synthesis of mesoporous silica, the acid pretreatment and alkali melt treatment of coal gasification slag have been passed. High silicon materials with high chemical activity were obtained, and the ordered mesoporous silica based materials with super specific surface area (1347 m2/g) and larger Kong Rong (0.83 cm3/g) were successfully prepared by sol-gel process. However, the sol-gel process was difficult to control in the industrial amplification due to the difficulty of controlling the precursor composition and homogeneity. In the process of synthesizing mesoporous silica based materials from raw materials, the mesoporous materials were prepared by chemical acid dissolution method for the first time. In view of the relationship between the strength of acid dissolution reaction and the specific surface area of the silicon base material obtained, a numerical model of the reaction strength was put forward in this study, and the pore forming process and mechanism of acid dissolution method were discussed with the model. The pore structure of the silicon based material is changed in the following order: no hole, wedge mesoporous, parallel plate mesoporous, cylindrical mesoporous, microporous and wedge-shaped mesoporous. Under the best reaction strength (RI=5327), the new mesoporous silicon-based material is a cylindrical mesoporous structure with large RI. Specific surface area (585.02m2/g) and Kong Rong (0.54 cm3/g). This proves that acid dissolution method can produce mesoporous silica based on sol-gel method. The acid dissolution process is simple, and the difficulty of industrialization will bring about changes in the synthesis field of mesoporous materials. The sol-gel method and acid dissolution method are obtained. The thermal stability of the two mesoporous silica based materials shows that the thermal stability of the latter is obviously superior to the former. After the treatment of 1H at 900 C, the pore volume of the MCM-41 obtained by the sol-gel method is only 15%, while the pore volume obtained by the acid dissolution method still holds 55%. in the application of mesoporous silica based materials for phase variable materials and the adsorption of heavy metals. At the same time, the influence of the pore shape on the application performance is discussed. The effective load rate (54.85%) of the silicon based material with a cylindrical mesoporous material is the largest when it is used as a phase change material carrier. The phase change heat of the fixed phase change material is 50.65 J/g, the phase change temperature is 30.9, and it has excellent performance in the cyclic thermal stability and leakage detection. The adsorption capacity of the mesoporous silica based materials synthesized directly on Cr and Pb adsorption is low. After the modification of chelating group EDTA and DTPA, the adsorption of cylindrical mesoporous silica based materials on Pb is greatly increased (17.30 mg/g and 16.90 mg/g), which is the best choice in the three pores. The modified mesoporous silica based materials are in heavy metals. The field of adsorption is very competitive.
【學(xué)位授予單位】：華東理工大學(xué)
【學(xué)位級別】：博士
【學(xué)位授予年份】：2016
【分類號】：TQ127.2;X705
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