錳氧化物的還原法制備及其室溫催化氧化甲醛研究
發(fā)布時間：2018-07-13 19:00
【摘要】：近年來,室內(nèi)環(huán)境質(zhì)量備受人們的關(guān)注,而甲醛污染物在室內(nèi)環(huán)境具有潛伏期長,釋放源多,釋放持續(xù)時間久等特點(diǎn),去除室內(nèi)甲醛污染物,改善室內(nèi)空氣質(zhì)量,與人們身體健康密不可分,引起了人們的廣泛關(guān)注。甲醛去除方法多種多樣,有通風(fēng)法、生物凈化法、吸附法、臭氧氧化法、光催化、低溫等離子體技術(shù)和催化氧化法等。其中,過渡金屬氧化物催化氧化法因其效率高、無污染和廉價等特點(diǎn)成為甲醛去除的研究熱點(diǎn)。本文以高錳酸鉀作氧化劑,分別選用甲醇和硫酸錳為還原劑,通過簡單的氧化還原反應(yīng)合成系列錳氧化物,并通過在反應(yīng)體系中加入酸或堿調(diào)控錳氧化物催化劑的物理化學(xué)性質(zhì),進(jìn)而影響其室溫催化氧化降解甲醛的性能。通過掃描電鏡(SEM)、X射線衍射(XRD)、拉曼光譜(Raman)、N2-吸附脫附、光電子能譜(XPS)、氫氣程序升溫還原(H2-TPR)、電感耦合等離子體原子發(fā)射光譜(ICP-AES)和原位紅外光譜(in situ-FTIR)等表征手段研究了催化劑的物理化學(xué)性質(zhì),在自行建立的動態(tài)、靜態(tài)測試系統(tǒng)上評價了合成的錳氧化物室溫催化氧化降解甲醛的性能,通過分析甲醛催化氧化的中間產(chǎn)物和最終產(chǎn)物,闡述了錳氧化物室溫催化氧化甲醛的機(jī)理。研究表明,甲醇還原高錳酸鉀制備的錳氧化物均屬水鈉錳礦,反應(yīng)體系中加入酸,能夠使催化劑的比表面積增大,表面吸附氧與晶格氧的比例降低,同時還降低了表面活性氧物種的還原溫度和晶格氧的起始還原溫度。以2.7 mL甲醇、9 g高錳酸鉀和1 mL硫酸為反應(yīng)條件制備的錳氧化物室溫催化氧化甲醛的反應(yīng)活性最高,甲醛降解率為91%,二氧化碳產(chǎn)率達(dá)89%。硫酸錳還原高錳酸鉀制備的錳氧化物屬于2×2隧道型隱鉀錳礦,加堿后制備的錳氧化物為層狀水鈉錳礦,堿參與硫酸錳和高錳酸鉀的反應(yīng),能提高催化劑的比表面積和表面吸附氧與晶格氧的比例,降低表面活性氧物種的還原溫度和晶格氧的起始還原溫度。在高錳酸鉀、硫酸錳和氫氧化鈉物質(zhì)量之比為2:3:2的條件下制備的錳氧化物室溫催化氧化甲醛的反應(yīng)活性最高,甲醛降解率為95%,二氧化碳產(chǎn)率為57%。
[Abstract]:In recent years, people pay more attention to indoor environmental quality, and formaldehyde pollutants in indoor environment have the characteristics of long incubation period, many sources of release, long duration of release, and so on, to remove indoor formaldehyde pollutants and improve indoor air quality. It is closely related to the health of people and has aroused widespread concern. There are many ways to remove formaldehyde, such as ventilation, biological purification, adsorption, ozone oxidation, photocatalysis, low-temperature plasma technology and catalytic oxidation. Among them, transition metal oxide catalytic oxidation method has become a hot research area for formaldehyde removal because of its high efficiency, no pollution and low cost. A series of manganese oxides were synthesized by simple redox reaction with potassium permanganate as oxidant and methanol and manganese sulfate as reductants respectively. The physical and chemical properties of manganese oxide catalysts were regulated by adding acid or base to the reaction system, which affected the catalytic oxidation and degradation of formaldehyde at room temperature. By scanning electron microscopy (SEM) X-ray diffraction (XRD), Raman spectroscopy (Raman) and N _ 2-adsorption desorption, Photoelectron spectroscopy (XPS), hydrogen temperature-programmed reduction (H2-TPR), inductively coupled plasma atomic emission spectrometry (ICP-AES) and in situ infrared spectroscopy (in situ FTIR) were used to study the physicochemical properties of the catalysts. The catalytic oxidation of formaldehyde by manganese oxide at room temperature was evaluated by static test system. The mechanism of oxidation of formaldehyde by manganese oxide at room temperature was described by analyzing the intermediate product and final product of catalytic oxidation of formaldehyde. The results show that the manganese oxides prepared by methanol reduction of potassium permanganate are all sodium manganese ores. Adding acid into the reaction system can increase the specific surface area of the catalyst and decrease the ratio of adsorbed oxygen to lattice oxygen on the surface. The reduction temperature of surface active oxygen species and the initial reduction temperature of lattice oxygen are also reduced. Under the conditions of 2.7 mL methanol 9 g potassium permanganate and 1 mL sulfuric acid as the reaction condition, manganese oxide has the highest catalytic activity for formaldehyde oxidation at room temperature, the degradation rate of formaldehyde is 91%, and the yield of carbon dioxide is 89%. Manganese oxide prepared by reduction of potassium permanganate with manganese sulfate belongs to 2 脳 2 tunnel type crypto-potassium manganese ore, and the manganese oxide prepared by adding alkali is layered sodium manganese ore. Alkali takes part in the reaction between manganese sulfate and potassium permanganate. The specific surface area of the catalyst and the ratio of surface adsorbed oxygen to lattice oxygen can be increased, and the reduction temperature of surface active oxygen species and the initial reduction temperature of lattice oxygen can be decreased. Under the condition that the mass ratio of potassium permanganate, manganese sulfate and sodium hydroxide is 2:3:2, the manganese oxide has the highest catalytic activity for formaldehyde oxidation at room temperature, the degradation rate of formaldehyde is 95%, and the yield of carbon dioxide is 57%.
【學(xué)位授予單位】：北京建筑大學(xué)
【學(xué)位級別】：碩士
【學(xué)位授予年份】：2017
【分類號】：X51
本文編號：2120436
[Abstract]:In recent years, people pay more attention to indoor environmental quality, and formaldehyde pollutants in indoor environment have the characteristics of long incubation period, many sources of release, long duration of release, and so on, to remove indoor formaldehyde pollutants and improve indoor air quality. It is closely related to the health of people and has aroused widespread concern. There are many ways to remove formaldehyde, such as ventilation, biological purification, adsorption, ozone oxidation, photocatalysis, low-temperature plasma technology and catalytic oxidation. Among them, transition metal oxide catalytic oxidation method has become a hot research area for formaldehyde removal because of its high efficiency, no pollution and low cost. A series of manganese oxides were synthesized by simple redox reaction with potassium permanganate as oxidant and methanol and manganese sulfate as reductants respectively. The physical and chemical properties of manganese oxide catalysts were regulated by adding acid or base to the reaction system, which affected the catalytic oxidation and degradation of formaldehyde at room temperature. By scanning electron microscopy (SEM) X-ray diffraction (XRD), Raman spectroscopy (Raman) and N _ 2-adsorption desorption, Photoelectron spectroscopy (XPS), hydrogen temperature-programmed reduction (H2-TPR), inductively coupled plasma atomic emission spectrometry (ICP-AES) and in situ infrared spectroscopy (in situ FTIR) were used to study the physicochemical properties of the catalysts. The catalytic oxidation of formaldehyde by manganese oxide at room temperature was evaluated by static test system. The mechanism of oxidation of formaldehyde by manganese oxide at room temperature was described by analyzing the intermediate product and final product of catalytic oxidation of formaldehyde. The results show that the manganese oxides prepared by methanol reduction of potassium permanganate are all sodium manganese ores. Adding acid into the reaction system can increase the specific surface area of the catalyst and decrease the ratio of adsorbed oxygen to lattice oxygen on the surface. The reduction temperature of surface active oxygen species and the initial reduction temperature of lattice oxygen are also reduced. Under the conditions of 2.7 mL methanol 9 g potassium permanganate and 1 mL sulfuric acid as the reaction condition, manganese oxide has the highest catalytic activity for formaldehyde oxidation at room temperature, the degradation rate of formaldehyde is 91%, and the yield of carbon dioxide is 89%. Manganese oxide prepared by reduction of potassium permanganate with manganese sulfate belongs to 2 脳 2 tunnel type crypto-potassium manganese ore, and the manganese oxide prepared by adding alkali is layered sodium manganese ore. Alkali takes part in the reaction between manganese sulfate and potassium permanganate. The specific surface area of the catalyst and the ratio of surface adsorbed oxygen to lattice oxygen can be increased, and the reduction temperature of surface active oxygen species and the initial reduction temperature of lattice oxygen can be decreased. Under the condition that the mass ratio of potassium permanganate, manganese sulfate and sodium hydroxide is 2:3:2, the manganese oxide has the highest catalytic activity for formaldehyde oxidation at room temperature, the degradation rate of formaldehyde is 95%, and the yield of carbon dioxide is 57%.
【學(xué)位授予單位】：北京建筑大學(xué)
【學(xué)位級別】：碩士
【學(xué)位授予年份】：2017
【分類號】：X51
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