TWI704955B - Modified carbonaceous material, carbon dioxide adsorbent and method for cellulose hydrolysis using the same - Google Patents
Modified carbonaceous material, carbon dioxide adsorbent and method for cellulose hydrolysis using the same Download PDFInfo
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Description
本發明是關於一種經官能基改質之碳材,尤指一種層狀碳結構邊緣處具有官能基之改質碳材、使用其之二氧化碳吸附劑及纖維素水解方法。The present invention relates to a carbon material modified with functional groups, in particular to a modified carbon material with functional groups at the edge of a layered carbon structure, a carbon dioxide adsorbent using the carbon material and a cellulose hydrolysis method.
碳質材料已應用於傳統及新技術之各種研究領域中。例如,CO 2捕集領域中已廣泛研究多孔碳材。在各種固體吸附劑中,多孔碳材因其具備理想的物理和化學特性而備受關注,例如低成本、多種形貌、易加工性、可控孔隙度及定制的表面化性。 Carbon materials have been used in various research fields of traditional and new technologies. For example, porous carbon materials have been extensively studied in the field of CO 2 capture. Among various solid adsorbents, porous carbon materials have attracted attention because of their ideal physical and chemical properties, such as low cost, multiple morphologies, easy processing, controllable porosity, and customized surface properties.
此外,一些研究者已對碳材作為各種反應催化劑之可能性進行探討。碳質催化劑對環境無害,且可提供成本競爭優勢。尤其,碳材之可調表面特性及優異的物理性質可與多種催化反應相容。舉例來說,碳表面上酸性官能基改質已於纖維素水解反應中進行相關研究,例如具有0.41 mmol g -1酸位點(acid site)密度之中孔碳(CMK-3)及含有0.88 mmol g -1酸位點密度之含氧鹼活性碳(K26)。然而,該些酸性官能碳基材料的水解效率仍有待改進。 In addition, some researchers have explored the possibility of carbon materials as catalysts for various reactions. Carbon-based catalysts are not harmful to the environment and can provide cost competitive advantages. In particular, the adjustable surface properties and excellent physical properties of carbon materials are compatible with various catalytic reactions. For example, the modification of acidic functional groups on the carbon surface has been studied in the cellulose hydrolysis reaction, such as mesoporous carbon (CMK-3) with acid site density of 0.41 mmol g -1 and containing 0.88 mmol g -1 acid site density of oxygen-containing alkali activated carbon (K26). However, the hydrolysis efficiency of these acid-functional carbon-based materials still needs to be improved.
由於上述原因及下述其他原因,亟需開發一種可解決水解效率問題及/或在其它各種應用中具有極大潛力之新的表面改質碳材。Due to the above reasons and other reasons described below, there is an urgent need to develop a new surface-modified carbon material that can solve the problem of hydrolysis efficiency and/or has great potential in various other applications.
本發明之目的係提供一種碳材,其具有高表面覆蓋率之酸性官能基,進而能夠用於纖維素水解或/及其他應用。該些酸性官能基主要存在於層狀碳結構的邊緣上,故層狀結構上緊密靠近的酸基團得以仿水解酶(如葡萄糖苷酶)的中心,進而提高水解效率。此外,該酸官能化碳材因其對於CO 2分子具有無法預期之較高吸附容量,故亦可應用於二氧化碳捕集和封存。 The object of the present invention is to provide a carbon material with acidic functional groups with high surface coverage, which can be used for cellulose hydrolysis or/and other applications. These acidic functional groups mainly exist on the edges of the layered carbon structure, so the acid groups closely adjacent to the layered structure can imitate the center of a hydrolase (such as glucosidase), thereby improving the hydrolysis efficiency. In addition, the acid-functionalized carbon material has an unpredictable high adsorption capacity for CO 2 molecules, so it can also be used for carbon dioxide capture and storage.
依據上述及其他目的,本發明提供一種改質碳材,其包括呈層狀堆疊結構之六角碳網以及鍵結至該些六角碳網之酸性官能基,其中大部分之該些酸性官能基係共價連結至該些六角碳網邊緣處之平面內(in-plane)sp 2碳。具體地說,於本發明中,該些酸性官能基之全部或複數者共價連結至六角碳網邊緣處之sp 2碳,其中該些酸性官能基中位於六角碳網之sp 2碳處的該些複數者在數量上係多於該些酸性官能基中連結至六角碳網之sp 3碳的其它者。 According to the above and other objectives, the present invention provides a modified carbon material, which includes a layered stacked structure of hexagonal carbon nets and acidic functional groups bonded to the hexagonal carbon nets, most of the acidic functional groups are Covalently linked to the in-plane sp 2 carbons at the edges of the hexagonal carbon meshes. Specifically, in the present invention, all or plural of the acidic functional groups are covalently linked to the sp 2 carbons at the edges of the hexagonal carbon network, wherein the acidic functional groups located at the sp 2 carbons of the hexagonal carbon network These plurals are more in number than the others connected to the sp 3 carbons of the hexagonal carbon network among the acidic functional groups.
基於 13C DP / MAS固態核磁共振(ssNMR)、拉曼光譜及X射線光電子能譜以研究酸性官能基與六角碳網間的關係,可發現酸性官能基主要存在於六角碳網邊緣處:(i) 13C固態NMR中實質上沒有或只有弱的sp 3碳峰(δ 22ppm); (ii)拉曼光譜所測得的I D/I G譜帶比不大於1(甚至不大於0.9); (iii)X射線光電子能譜所測得的C1s/O1s比值不小於3(甚至不小於4)。 Based on 13 C DP / MAS solid-state nuclear magnetic resonance (ssNMR), Raman spectroscopy and X-ray photoelectron spectroscopy to study the relationship between acidic functional groups and the hexagonal carbon network, it can be found that the acidic functional groups mainly exist at the edge of the hexagonal carbon network: ( i) 13 C solid state NMR substantially no or only weak sp 3 carbon peak (δ 22ppm); (ii) a Raman spectrum measured by the I D / I G ratio of not more than 1 band (even not greater than 0.9) (Iii) The C1s/O1s ratio measured by X-ray photoelectron spectroscopy is not less than 3 (or even not less than 4).
於本發明中,該改質碳材可藉由瀝青類材料,如介相瀝青 (mesophase pitch 簡稱MP)進行酸改質製得,使酸性官能基主要形成於層狀堆疊結構中之芳香環平面的邊緣上。據此,可合成出一系列具有高密度酸性官能基之非孔洞碳材,其於纖維素水解中可展現提高的催化效率。具體地說,根據一較佳具體實施例,該改質碳材透過氮氣吸附而測得其具有低於56 m 2/g之比表面積以及約1.5 mmol/g(例如1.5~4.0 mmol /g)或更高的總酸位點密度,其大於中孔碳(CMK-3)及含氧鹼活性碳(K26)。 In the present invention, the modified carbon material can be prepared by acid modification of pitch materials, such as mesophase pitch (MP), so that acidic functional groups are mainly formed on the aromatic ring plane in the layered stacked structure On the edge. Accordingly, a series of non-porous carbon materials with high density of acidic functional groups can be synthesized, which can exhibit improved catalytic efficiency in cellulose hydrolysis. Specifically, according to a preferred embodiment, the modified carbon material has a specific surface area of less than 56 m 2 /g and about 1.5 mmol/g (for example, 1.5~4.0 mmol/g) through nitrogen adsorption. Or higher total acid site density, which is greater than mesoporous carbon (CMK-3) and oxygen-containing alkali activated carbon (K26).
於本發明中,該改質碳材經X光繞射可測得其具有約0.34 nm至約0.37 nm範圍之層間距離。 據此,邊緣上緊密靠近之酸性官能基可仿水解酶的中心,進而產生較佳之水解效率。In the present invention, the modified carbon material has an interlayer distance in the range of about 0.34 nm to about 0.37 nm as measured by X-ray diffraction. According to this, the acidic functional groups close to the edge can imitate the center of the hydrolase, thereby resulting in better hydrolysis efficiency.
於本發明中,包含有六角碳網之該瀝青類材料可以硫酸、硝酸或次氯酸鹽進行處理,隨後可選擇進行水熱處理。據此,該瀝青類材料可改質成具有高表面覆蓋率之酸性官能基,如磺酸基(sulfonic)、羧基(carboxyl)、內酯(lactone)及酚羥基(phenolic hydroxyl),其主要位於層狀結構的邊緣上。In the present invention, the pitch material containing the hexagonal carbon mesh can be treated with sulfuric acid, nitric acid or hypochlorite, and then optionally subjected to hydrothermal treatment. Accordingly, the asphalt-based materials can be modified into acidic functional groups with high surface coverage, such as sulfonic, carboxyl, lactone and phenolic hydroxyl, which are mainly located in On the edge of the layered structure.
於硫酸處理之態樣中,幾乎所有的酸性官能基皆共價連結於實質上由芳香族碳所組成的六角碳網之邊緣處之平面內sp 2碳。因此,經硫酸處理之碳材在 13C CP/MAS NMR光譜中實質上並未觀察到有sp 3碳峰。此表示,經硫酸處理之碳材實質上不具有脂肪族碳(aliphatic carbons)。以硫酸進行酸改質後,該改質碳材可具有約2.0 mmol/g或更高(如2.0~3.5 mmol/g)的總酸位點密度。包含於經硫酸處理之碳材中的磺酸基(sulfonic groups)、酚羥基(phenolic hydroxyl groups)、羧基(carboxyl groups)及內酯基(lactone groups)密度可分別為約0.8 mmol/g或更高(如0.8~1.5 mmol/g)、約0.5 mmol/g或更高(如0.5~0.8 mmol/g)、約0.1 mmol/g或更高(如0.1 ~0.3 mmol/g)、約0.4 mmol/g或更高(如0.4~0.9 mmol/g)。於本發明之一具體實施例中,已證實該經硫酸處理之碳材具有約0.7至約0.9之I D/I G比值以及約4.0至約6.0之C1s/O1s比值。 In the state of sulfuric acid treatment, almost all acidic functional groups are covalently connected to the in-plane sp 2 carbons at the edges of the hexagonal carbon network substantially composed of aromatic carbons. Therefore, the carbon material treated with sulfuric acid has no sp 3 carbon peak observed in the 13 C CP/MAS NMR spectrum. This means that the sulfuric acid-treated carbon material does not substantially contain aliphatic carbons. After acid-modified with sulfuric acid, the modified carbon material may have a total acid site density of about 2.0 mmol/g or higher (such as 2.0-3.5 mmol/g). The density of sulfonic groups, phenolic hydroxyl groups, carboxyl groups and lactone groups contained in the sulfuric acid-treated carbon material can be about 0.8 mmol/g or more, respectively. High (such as 0.8~1.5 mmol/g), about 0.5 mmol/g or higher (such as 0.5~0.8 mmol/g), about 0.1 mmol/g or higher (such as 0.1 ~0.3 mmol/g), about 0.4 mmol /g or higher (such as 0.4~0.9 mmol/g). One embodiment of the present invention, in the particular embodiment, it has been confirmed that treatment of the carbon material having a sulfation of from about 0.7 to about 0.9 I D / I G ratio and C1s of about 4.0 to about 6.0 / O1s ratio.
於硝酸或次氯酸鹽處理之另一態樣中,酸性官能基不僅只於材料邊緣處進行改質,其亦有部分係於苯環上改質。因此,經硝酸及經次氯酸處理之碳材在 13C CP/MAS NMR光譜中可觀察到弱的sp 3碳峰。以硝酸或次氯酸鹽進行酸改質後,該改質碳材可具有約1.5 mmol/g或更高(如1.5~2.5 mmol/g)的總酸位點密度。包含於經硝酸或次氯酸處理之碳材中的酚羥基、羧基及內酯基密度可分別為約0.3 mmol/g或更高(如0.3~0.8 mmol/g)、約0.2 mmol/g或更高(如0.2~1.5 mmol/g)、約0.3 mmol/g或更高(如0.3 ~0.9 mmol/g)。於本發明之一具體實施例中,已證實該經硝酸或次氯酸處理之碳材具有約0.9至約1.0之I D/I G比值以及約3.0至約4.0之C1s/O1s比值。 In another aspect of nitric acid or hypochlorite treatment, the acidic functional groups are not only modified at the edges of the material, but also partially modified on the benzene ring. Therefore, carbon materials treated with nitric acid and hypochlorous acid have a weak sp 3 carbon peak in the 13 C CP/MAS NMR spectrum. After acid-modified with nitric acid or hypochlorite, the modified carbon material may have a total acid site density of about 1.5 mmol/g or higher (such as 1.5-2.5 mmol/g). The density of phenolic hydroxyl group, carboxyl group and lactone group contained in the carbon material treated with nitric acid or hypochlorous acid may be about 0.3 mmol/g or higher (such as 0.3-0.8 mmol/g), about 0.2 mmol/g or Higher (such as 0.2 to 1.5 mmol/g), about 0.3 mmol/g or higher (such as 0.3 to 0.9 mmol/g). In one embodiment of the present invention, it has been confirmed that the carbonaceous material with nitric acid or hypochlorous acid treatment of about 0.9 to about 1.0 of the I D / I G ratio of from about 3.0 to about 4.0 and of C1s / O1s ratio.
有鑑於該改質碳材於纖維素水解中具有良好的催化效率,本發明更進一步提供一種纖維素水解方法,包括:於水溶液中混合上述改質碳材與纖維素;以及於該改質碳材作為催化劑之存在下以一預定溫度進行該纖維素之水解。該預定溫度可為130°C至210°C範圍。於本發明之一具體實施例中,已證實該改質碳材可以4.8 mol%(酸基/纖維素)之催化比率降解纖維素(如結晶相纖維素、非晶相纖維素及預水解纖維素)。此外,可觀察到只有低於3 mol%之葡萄糖產率係由磺酸基浸出水解反應所造成。據此,可得知本發明之改質碳材具備水解穩定性,以致於整個催化過程更加有效率且環保。In view of the good catalytic efficiency of the modified carbon material in cellulose hydrolysis, the present invention further provides a cellulose hydrolysis method, including: mixing the modified carbon material and cellulose in an aqueous solution; and applying the modified carbon The cellulose is hydrolyzed at a predetermined temperature in the presence of the material as a catalyst. The predetermined temperature may range from 130°C to 210°C. In a specific embodiment of the present invention, it has been proved that the modified carbon material can degrade cellulose (such as crystalline phase cellulose, amorphous phase cellulose and pre-hydrolyzed fiber) at a catalytic ratio of 4.8 mol% (acid base/cellulose) Vegetarian). In addition, it can be observed that only less than 3 mol% of the glucose yield is caused by the sulfonic acid group leaching and hydrolysis reaction. According to this, it can be known that the modified carbon material of the present invention has hydrolytic stability, so that the entire catalytic process is more efficient and environmentally friendly.
於本發明中,已證實可通過中和酸性官能基團以達成改質鹼官能基團,此鹼性官能化表面可將葡萄糖異構化為果糖,其選擇性高達90%,此表示共軛鹼可用於葡萄糖之鹼催化異構化。In the present invention, it has been proved that the basic functional group can be modified by neutralizing the acidic functional group. This basic functionalized surface can isomerize glucose to fructose with a selectivity of up to 90%, which means conjugation Alkali can be used for base-catalyzed isomerization of glucose.
再者,基於CO 2吸附分析,可得知本發明之酸官能化材料具備CO 2封存潛力。據此,本發明更提供一種捕集CO 2之酸官能化吸附劑,其包括呈層狀堆疊結構之六角碳網以及鍵結至該些六角碳網之酸性官能基,其中該些六角碳網實質上係由芳香族碳所組成,且實質上全部之該些酸性官能基係共價連結於該些六角碳網邊緣處之平面內sp 2碳。於本發明之一具體實施例中,已證實本發明之改質碳材展現高達約11 wt%(重量百分比)之高二氧化碳吸附量。 Furthermore, based on CO 2 adsorption analysis, it can be known that the acid functionalized material of the present invention has the potential for CO 2 storage. Accordingly, the present invention further provides an acid-functionalized adsorbent for capturing CO 2 which includes hexagonal carbon nets in a layered stacked structure and acidic functional groups bonded to the hexagonal carbon nets, wherein the hexagonal carbon nets It is substantially composed of aromatic carbons, and substantially all of the acidic functional groups are covalently connected to the in-plane sp 2 carbons at the edges of the hexagonal carbon meshes. In one specific embodiment of the present invention, it has been confirmed that the modified carbon material of the present invention exhibits a high carbon dioxide adsorption capacity of up to about 11 wt% (weight percentage).
本說明書及隨附申請專利範圍中所使用之「大部分之酸性官能基」用語係以材料中酸性官能基之個數百分比來定義。亦即,材料總酸性官能基中有超過50%的酸性官能基係改質於材料的邊緣處。例如,材料總酸性官能基中有至少60%的酸性官能基係改質於材料的邊緣處。例如,材料總酸性官能基中有至少70%的酸性官能基係改質於材料的邊緣處。例如,材料總酸性官能基中有至少80%的酸性官能基係改質於材料的邊緣處。例如,材料總酸性官能基中有至少90%的酸性官能基係改質於材料的邊緣處。The term "most of the acidic functional groups" used in this specification and the accompanying patent application is defined by the percentage of acidic functional groups in the material. That is, more than 50% of the total acidic functional groups of the material are modified at the edges of the material. For example, at least 60% of the total acidic functional groups of the material are modified at the edges of the material. For example, at least 70% of the total acidic functional groups of the material are modified at the edges of the material. For example, at least 80% of the total acidic functional groups of the material are modified at the edges of the material. For example, at least 90% of the total acidic functional groups of the material are modified at the edges of the material.
本發明之上述及其他目的、優點與新特徵可藉由下述參考隨附圖式之詳細敘述更加清楚明瞭。The above and other objectives, advantages and new features of the present invention can be more clearly understood by the following detailed description with reference to the accompanying drawings.
實施例- 製備官能化介相瀝青 Example- Preparation of functionalized mesophase pitch
於進一步處理和反應之前,研磨介相瀝青(軟化點:275-295℃, 日本‧三菱瓦斯化學株式會社),並於230目篩網中篩分至粒徑為63微米。Before further processing and reaction, the mesophase pitch (softening point: 275-295℃, Mitsubishi Gas Chemical Co., Ltd., Japan) is ground and sieved on a 230-mesh screen to a particle size of 63 microns.
[MP-SO 3H] [MP-SO 3 H]
利用濃H 2SO 4(95-97% SO 3)溶液作為氧化劑,以合成官能化介相瀝青(SO 3H-MP)。於乾燥氮氣環境下,在濃硫酸中加熱80℃達20小時,接著加熱150℃至7小時,以對介相瀝青(1.2 g)進行磺酸化。於反應後,過濾收集官能化MPs,並以大量水清洗。接著將材料以500 mL水進行索氏(Soxhlet)萃取8小時,並重覆兩次此萃取程序。最後,將改質後材料置於冷凍乾燥機中進行乾燥。 Use concentrated H 2 SO 4 (95-97% SO 3 ) solution as oxidant to synthesize functionalized mesophase pitch (SO 3 H-MP). In a dry nitrogen environment, heat at 80°C for 20 hours in concentrated sulfuric acid, and then heat at 150°C to 7 hours to sulfonate the mesophase pitch (1.2 g). After the reaction, the functionalized MPs were collected by filtration and washed with a large amount of water. Then the material was subjected to Soxhlet extraction with 500 mL of water for 8 hours, and this extraction procedure was repeated twice. Finally, the modified material is placed in a freeze dryer for drying.
[MP-SO 3H-HT] [MP-SO 3 H-HT]
對MP-SO 3H重覆三次水熱處理,以製得MP-SO 3H-HT。將MP-SO 3H(0.5 g)置於高壓釜中以30 mL水於200 °C下8小時。於水熱處理後,過濾收集材料,並以索氏萃取程序進行清洗。重覆相同步驟兩次,以合成MP-SO 3H-HT。 The hydrothermal treatment of MP-SO 3 H was repeated three times to prepare MP-SO 3 H-HT. Place MP-SO 3 H (0.5 g) in an autoclave with 30 mL of water at 200 °C for 8 hours. After the hydrothermal treatment, the material was collected by filtration and cleaned by Soxhlet extraction procedure. Repeat the same step twice to synthesize MP-SO 3 H-HT.
[MP-COOH][MP-COOH]
將500 mg的MPs置於100 mL圓底瓶中,以50 mL的不同濃度(7.9 M、7 M、6 M、5 M、4 M或1 M)的硝酸合成MP-COOH。於105 °C下迴流溶液1.5至3小時。於反應後,過濾收集官能性MPs,並以大量水清洗。將獲得之材料以500 mL水進行索氏萃取8小時,並重覆兩次。最後,將改質後材料置於冷凍乾燥機中進行乾燥。在不同反應條件中,濃度6M及反應1.5小時的條件被認為是羧酸基的最佳條件。因此,將以濃度6M及反應1.5小時的條件所合成的MP-COOH進行後續分析。Put 500 mg of MPs in a 100 mL round bottom bottle, and synthesize MP-COOH with 50 mL of nitric acid with different concentrations (7.9 M, 7 M, 6 M, 5 M, 4 M, or 1 M). Reflux the solution at 105 °C for 1.5 to 3 hours. After the reaction, the functional MPs were collected by filtration and washed with a large amount of water. The obtained material was subjected to Soxhlet extraction with 500 mL of water for 8 hours and repeated twice. Finally, the modified material is placed in a freeze dryer for drying. Among the different reaction conditions, the concentration of 6M and the reaction for 1.5 hours are considered to be the best conditions for the carboxylic acid group. Therefore, the MP-COOH synthesized under the conditions of a concentration of 6M and a reaction time of 1.5 hours will be subjected to subsequent analysis.
此外,亦可對經預處理的材料進行改質以製得MP- COOH:於不同氣體下(氮氣及空氣),以250°C或280°C燒結MPs (300mg)達2小時、4小時或6小時,接著再加入30 mL硝酸(7.9 M、7 M、6 M、5 M、4 M或1 M)於105 °C下反應1.5小時或3小時。In addition, the pretreated material can also be modified to produce MP-COOH: under different gases (nitrogen and air), sintering MPs (300mg) at 250°C or 280°C for 2 hours, 4 hours or 6 hours, then add 30 mL of nitric acid (7.9 M, 7 M, 6 M, 5 M, 4 M, or 1 M) and react at 105 °C for 1.5 hours or 3 hours.
[MP-Oxy][MP-Oxy]
將500 mg的MPs置於具有5%次氯酸鈉(250 mL)之500 mL圓底瓶中,並以37%濃度之次氯酸調整pH至約4~5,於30 °C下反應12小時、18小時或24小時,以合成MP-Oxy。於反應後,過濾收集官能性MPs,並以大量水清洗。將獲得的材料以500 mL水進行索氏萃取8小時,並重覆兩次。於不同反應時間下合成之MP-Oxy材料中,將選擇經過24小時處理的材料進行後續分析。於酸改質後,可選擇進行一次水熱處理,以修復MP-Oxy材料結構,獲得MP-Oxy-HT。Put 500 mg of MPs in a 500 mL round-bottomed bottle with 5% sodium hypochlorite (250 mL), adjust the pH to about 4 to 5 with 37% hypochlorous acid, and react at 30 °C for 12 hours, 18 Hours or 24 hours to synthesize MP-Oxy. After the reaction, the functional MPs were collected by filtration and washed with a large amount of water. The obtained material was subjected to Soxhlet extraction with 500 mL of water for 8 hours and repeated twice. Among the MP-Oxy materials synthesized under different reaction times, the materials that have been processed for 24 hours will be selected for subsequent analysis. After acid reformation, a hydrothermal treatment can be selected to repair the structure of MP-Oxy material and obtain MP-Oxy-HT.
比較例- 製備MCN-HSO 3 Comparative Example- Preparation of MCN-HSO 3
使用發煙H 2SO 4(20% SO 3)溶液作為氧化劑,以及mesoporous carbon nanoparticles (簡稱MCN) 中孔碳奈米粒子,合成官能化中孔碳奈米粒子材料(HSO 3-MCN)。於圓底瓶(50 mL)中以發煙硫酸溶液(80 mL)處理MCN材料(1.2 g),並於氮氣及80 °C下加熱混合物至24小時。於反應後,過濾收集合成得的官能性MCN,並以大量水清洗。將合成出的MCN材料(1.2 g)以250 mL水進行索氏萃取3小時,並重覆連續四次此萃取程序。 Using fuming H 2 SO 4 (20% SO 3 ) solution as oxidant and mesoporous carbon nanoparticles (MCN for short) mesoporous carbon nanoparticles, functionalized mesoporous carbon nanoparticle materials (HSO 3 -MCN) were synthesized. The MCN material (1.2 g) was treated with fuming sulfuric acid solution (80 mL) in a round bottom flask (50 mL), and the mixture was heated at 80 °C under nitrogen for 24 hours. After the reaction, the synthesized functional MCN was collected by filtration, and washed with a large amount of water. The synthesized MCN material (1.2 g) was subjected to Soxhlet extraction with 250 mL of water for 3 hours, and this extraction procedure was repeated four consecutive times.
氮氣與二氧化碳氣體等溫吸附Nitrogen and carbon dioxide gas isotherm adsorption
於1×10 -6mmHg真空度下,利用Micromeritics 3Flex分析儀進行樣品之氮氣(N 2)與二氧化碳氣體(CO 2)等溫吸附分析。於液態氮溫度(77 K)下,分析相對壓力(P/P 0) 介於0.05和0.995之間的N 2等溫吸附曲線,並於相對壓力(P/P 0)介於0.05和0.3之間的範圍下獲得Brunauer-Emmett-Teller (BET)比表面積。於273 K(P 0= 26,142 mmHg)及298 K (P 0= 48,273 mmHg)下,相對分析壓力(P/P 0)介於0.0003和0.03之間的CO 2等溫吸附曲線。使用Micromeritics ISO控制器(0.1°C內)達到CO 2分析溫度。最初使用Micromeritics Smart VacPrep脫氣裝置,於393K、1×10 -3mmHg真空度下對樣品(50 mg)進行脫氣12小時。使用純度為99.996%之氦氣(He),測定樣品管內之自由空間。樣品之氮氣(N 2)等溫吸附曲線圖示於圖1及2中,而樣品之二氧化碳氣體(CO 2)等溫吸附曲線圖示於圖3中。 Under a vacuum of 1×10 -6 mmHg, a Micromeritics 3Flex analyzer was used to perform the adsorption isotherm analysis of nitrogen (N 2 ) and carbon dioxide (CO 2 ) of the sample. Under the temperature of liquid nitrogen (77 K), analyze the N 2 adsorption isotherm curve with the relative pressure (P/P 0 ) between 0.05 and 0.995, and the relative pressure (P/P 0 ) between 0.05 and 0.3 The Brunauer-Emmett-Teller (BET) specific surface area is obtained under the range of time. At 273 K (P 0 = 26,142 mmHg) and 298 K (P 0 = 48,273 mmHg), the relative analysis pressure (P/P 0 ) is between 0.0003 and 0.03 CO 2 adsorption isotherm curve. Use Micromeritics ISO controller (within 0.1°C) to reach CO 2 analysis temperature. Initially, the Micromeritics Smart VacPrep degassing device was used to degas the sample (50 mg) at 393K and a vacuum of 1×10 -3 mmHg for 12 hours. Use helium (He) with a purity of 99.996% to measure the free space in the sample tube. The nitrogen (N 2 ) adsorption isotherm of the sample is shown in Figures 1 and 2, and the carbon dioxide (CO 2 ) adsorption isotherm of the sample is shown in Figure 3.
結果顯示,所有材料之表面積(MP-HSO 3表面積為55.2 m 2/g,MP-HSO 3-HT表面積為25.2 m 2/g,MP-COOH表面積為2.18 m 2/g,MP-Oxy表面積為1.56 m 2/g)相對低於其他多孔材料。此表示官能性MPs為非孔洞材料。於線形氣體分子(CO 2)物理吸附研究(273K)中,令人感到意外的是MP-SO 3H及 MP-SO 3H-HT展現高的CO 2吸附容量(MP-SO 3H為2.46 mmol/g,MP-SO 3H-HT為2.23 mmol/g),其呈II型等溫曲線。在MP-SO 3H和MP-SO 3H-HT中觀察到相當大量之CO 2物理吸附是出人意料的現象,因為此與使用高表面積或具有鹼官能基材料進行CO 2封存的習知概念是相互衝突的。 The results show that the surface area of all materials (MP-HSO 3 surface area is 55.2 m 2 /g, MP-HSO 3 -HT surface area is 25.2 m 2 /g, MP-COOH surface area is 2.18 m 2 /g, MP-Oxy surface area is 1.56 m 2 /g) is relatively lower than other porous materials. This means that functional MPs are non-porous materials. In the study of physical adsorption of linear gas molecules (CO 2 ) (273K), it is surprising that MP-SO 3 H and MP-SO 3 H-HT exhibit high CO 2 adsorption capacity (MP-SO 3 H is 2.46 mmol/g, MP-SO 3 H-HT is 2.23 mmol/g), which shows a type II isotherm. In MP-SO 3 H and MP-SO 3 H-HT, it is an unexpected phenomenon to observe a considerable amount of CO 2 physical adsorption, because it is different from the conventional concept of CO 2 storage using high surface area or basic functional group materials. Conflicting.
酸位點密度測定Acid site density determination
基於反式滴定法(Boehm's method)進行酸位點測定,並利用元素分析以分析硫,其表示為磺酸基(sulfonic)。使用不同鹼溶液對各個官能基進行Boehm選擇性中和,以測定如羧基、內酯及酚羥基之官能基:氫氧化鈉(NaOH)用於測定三種官能基;碳酸鈉(Na 2CO 3)用於測定羧基及內酯;碳酸氫鈉(NaHCO 3)僅用於測定羧酸。所有的酸及鹼溶液(HCl、NaOH、Na 2CO 3、NaHCO 3、KHP)皆配製成0.01 M濃度。由於NaOH濃度容易因暴露於空氣中CO 2而改變,故使用鄰苯二甲酸氫鉀(Potassium Hydrogen Phthalate, KHP)交叉確定配製成的氫氧化鈉濃度。獲得的濃度值為氫氧化鈉濃度。隨後,以NaOH滴定HCl,以測得HCl濃度。最後,使用HCl確定Na 2CO 3及NaHCO 3濃度。使用酚酞作為用於NaOH溶液的指示劑,並使用溴甲酚綠作為用於Na 2CO 3及NaHCO 3溶液的指示劑。 The acid site determination is performed based on the trans titration method (Boehm's method), and elemental analysis is used to analyze sulfur, which is expressed as a sulfonic group. Use different alkali solutions to perform Boehm selective neutralization of each functional group to determine functional groups such as carboxyl, lactone and phenolic hydroxyl: sodium hydroxide (NaOH) is used to determine three functional groups; sodium carbonate (Na 2 CO 3 ) Used for the determination of carboxyl and lactone; sodium bicarbonate (NaHCO 3 ) is only used for the determination of carboxylic acid. All acid and alkali solutions (HCl, NaOH, Na 2 CO 3 , NaHCO 3 , KHP) are formulated to a concentration of 0.01 M. Since the concentration of NaOH is easily changed by exposure to CO 2 in the air, Potassium Hydrogen Phthalate (KHP) is used to determine the concentration of sodium hydroxide. The concentration value obtained is the sodium hydroxide concentration. Subsequently, HCl was titrated with NaOH to measure the HCl concentration. Finally, use HCl to determine the concentration of Na 2 CO 3 and NaHCO 3 . Phenolphthalein was used as an indicator for NaOH solutions, and bromocresol green was used as an indicator for Na 2 CO 3 and NaHCO 3 solutions.
依下述方法進行Boehm滴定:將50 mg材料(MP系列材料)加至50 mL管中之20 mL每種鹼溶液(NaOH、Na 2CO 3及NaHCO 3)中。將所有三個樣品渦旋2小時後過濾回收溶液。 隨後,用HCl滴定每種鹼回收溶液。 從HCl對應滴定的鹼溶液測得酸位點。分別使用NaHCO 3、Na 2CO 3及NaOH,計算羧酸、羧基與內酯相加、以及總酸位點。 苯酚密度則由NaOH與Na 2CO 3測定的密度差算得。利用下述等式算得每組的酸位點(acid site): 。 Carry out Boehm titration as follows: add 50 mg of material (MP series material) to 20 mL of each alkali solution (NaOH, Na 2 CO 3 and NaHCO 3 ) in a 50 mL tube. After vortexing all three samples for 2 hours, the solution was recovered by filtration. Subsequently, each alkali recovery solution was titrated with HCl. The acid site is measured from the alkali solution corresponding to the titration of HCl. Using NaHCO 3 , Na 2 CO 3 and NaOH, respectively, calculate the addition of carboxylic acid, carboxyl group and lactone, and total acid sites. The density of phenol is calculated from the density difference measured by NaOH and Na 2 CO 3 . Use the following equation to calculate the acid site of each group: .
研究結果顯示,MP-HSO 3-HT之總酸位點(2.25 mmol/g)低於MP-HSO 3(3.12 mmol/g),此是因為水熱處理會移除MP-HSO 3-HT的官能基。此外,MP-COOH之總酸位點(2.00 mmol/g)低於MP-HSO 3或MP-HSO 3-HT,此表示硝酸的氧化不如硫酸的好,而MP-Oxy的總酸度(1.96 mmol/g)是所有材料中最低的。 The research results show that the total acid sites of MP-HSO 3 -HT (2.25 mmol/g) are lower than that of MP-HSO 3 (3.12 mmol/g). This is because the hydrothermal treatment will remove the functionalities of MP-HSO 3 -HT. base. In addition, the total acid sites of MP-COOH (2.00 mmol/g) are lower than MP-HSO 3 or MP-HSO 3 -HT, which means that the oxidation of nitric acid is not as good as that of sulfuric acid, and the total acidity of MP-Oxy (1.96 mmol/g) /g) is the lowest of all materials.
未處理的MP和官能化MPs的酸位點分佈示於下表1中。The acid site distribution of untreated MPs and functionalized MPs is shown in Table 1 below.
[表1] [Table 1]
粉末 X光繞射( PXRD) Powder X- ray diffraction ( PXRD )
在該實驗中,藉由Bruker D8 Advance光譜儀記錄粉末XRD光譜,其係於40kW的電壓下操作,並用CuKα輻射(λ= 1.5418 Å)產生40mA的電流。 掃描角度為10°至90°,掃描速率為6°/分鐘。In this experiment, a Bruker D8 Advance spectrometer was used to record powder XRD spectra, which was operated at a voltage of 40 kW and CuKα radiation (λ = 1.5418 Å) was used to generate a current of 40 mA. The scanning angle is 10° to 90°, and the scanning rate is 6°/min.
MP系列材料之XRD圖在2θ角為24°-25°處顯示訊號峰,其可解釋為非晶相碳結構之(002)面。 相較於未改質MP之高強度峰相,改質材料在相同角度處顯示出寬且弱的訊號峰,此表示氧化處理使得晶相變弱,且層狀結構呈隨機堆疊。The XRD pattern of MP series materials shows a signal peak at a 2θ angle of 24°-25°, which can be interpreted as the (002) plane of the amorphous carbon structure. Compared with the high-intensity peak phase of the unmodified MP, the modified material shows a broad and weak signal peak at the same angle, which means that the oxidation treatment makes the crystal phase weaker and the layered structure is randomly stacked.
此外,通過布拉格定律(Bragg's Law)2d(hkl)sinθ=nλ計算所有材料的d-spacing(其層間結構的距離)如下:0.366 nm (MP-HSO 3)、0.366nm(MP-HSO 3-HT)、0.343 nm(MP-COOH)及0.345 nm(MP-Oxy)。 Further, by Bragg's law (Bragg's Law) 2d (hkl ) sinθ = nλ calculate all material d-spacing (distance between its layer structure) as follows: 0.366 nm (MP-HSO 3 ), 0.366nm (MP-HSO 3 -HT ), 0.343 nm (MP-COOH) and 0.345 nm (MP-Oxy).
傅立葉轉換紅外光譜(FTIR ) Fourier transform infrared spectroscopy (FTIR )
官能化MP材料之FTIR光譜示於圖4。在MP-SO 3H及MP-SO 3H-HT上1027cm -1和1151cm -1處之譜帶係指磺酸基團(SO 3H)之S-O及S=O不對稱及對稱伸縮。1326cm -1處之譜帶則指C-O伸縮。 1521~1596 cm -1處之譜帶係歸因於石墨結構的C = C伸縮模式。 1712cm -1處之譜帶係指羧酸基的C = O伸縮模式。 此外,2850~3045cm -1之間的譜帶係歸因於C-H伸縮模式,而位於3300~3400cm -1之間的譜帶係歸因於羧酸基和酚酸上的OH官能基。 The FTIR spectrum of the functionalized MP material is shown in Figure 4. The bands at 1027 cm -1 and 1151 cm -1 on MP-SO 3 H and MP-SO 3 H-HT refer to the asymmetric and symmetrical stretching of SO and S=0 of the sulfonic acid group (SO 3 H). The band at 1326cm -1 refers to CO stretching. The band at 1521~1596 cm -1 is attributed to the C = C stretching mode of the graphite structure. The band at 1712 cm -1 refers to the C=O stretching mode of the carboxylic acid group. In addition, the band between 2850 and 3045 cm -1 is due to the CH stretching mode, and the band between 3300 and 3400 cm -1 is due to the carboxylic acid group and the OH functional group on the phenolic acid.
13 C 固態核磁共振 (SSNMR ) 13 C solid state nuclear magnetic resonance ( SSNMR )
13C固態核磁共振光譜( 13C DP-mass rotation, 13C DP-MAS)示於圖5。MP光譜有兩個主峰,其中心化學位移為22 ppm及125 ppm,此表示有兩種主要化學組成,其分別為脂肪族碳及芳香族碳。於MP-SO 3H和MP-SO 3H-HT光譜中,未明顯觀察到脂肪族的碳峰,而芳香族的碳峰則往低場稍微位移,其新峰值中心位於化學位移180 ppm處,此可代表氧化基團,如羧酸。與磺酸相鄰之芳香族碳的化學位移可能已併於約130 ppm處,其變得難以從其他芳香族碳中區分出來。除了上述結果外,亦發現MP-COOH和MP-Oxy仍具有脂肪族的碳峰,其中MP-Oxy於化學位移為57 ppm處具有新峰。根據文獻,此為O-烷基-C基團。上述結果證實,酸性官能基的改質主要發生在材料的邊緣,而MP-COOH和MP-Oxy在苯環上有少許酸性官能基的改質。 The 13 C solid-state nuclear magnetic resonance spectrum ( 13 C DP-mass rotation, 13 C DP-MAS) is shown in Figure 5. The MP spectrum has two main peaks, and the center chemical shifts are 22 ppm and 125 ppm, which means that there are two main chemical compositions, which are aliphatic carbon and aromatic carbon. In the spectra of MP-SO 3 H and MP-SO 3 H-HT, the aliphatic carbon peak is not clearly observed, while the aromatic carbon peak is slightly shifted to the lower field, and the new peak center is at the chemical shift 180 ppm , This can represent an oxidizing group, such as a carboxylic acid. The chemical shift of the aromatic carbon adjacent to the sulfonic acid may have merged at about 130 ppm, making it difficult to distinguish it from other aromatic carbons. In addition to the above results, it is also found that MP-COOH and MP-Oxy still have aliphatic carbon peaks, and MP-Oxy has a new peak at a chemical shift of 57 ppm. According to the literature, this is an O-alkyl-C group. The above results confirm that the modification of acidic functional groups mainly occurs at the edge of the material, while MP-COOH and MP-Oxy have a little modification of acidic functional groups on the benzene ring.
X 射線光電子能譜(XPS ) X -ray photoelectron spectroscopy ( XPS )
XPS分析示於圖6。由下式算得C/O比值:[(C1S的積分面積)/(C1S的敏感因子)/(O1S的積分面積)/(O1S的敏感因子)]。 分析結果表示,未官能化材料MP的C/O比值為4.89,而官能性材料MP-SO 3H、MP-SO 3H-HT、MP-COOH和MP-Oxy的C/O比值分別為5.85、4.75、3.72和3.32。 MP-SO 3H具有較高比值係因為大多數的官能基在邊緣處改質。 至於MP-SO 3H-HT,由於水熱處理後羥基會取代磺化基,故MP-SO 3H-HT的C/O比值會降低。 MP-COOH和MP-Oxy的官能基不僅在材料邊緣處進行改質,其亦在苯環上進行部分改質,因而導致較低的C/O比值。 The XPS analysis is shown in Figure 6. The C/O ratio is calculated from the following formula: [(C1S integrated area)/(C1S sensitive factor)/(O1S integrated area)/(O1S sensitive factor)]. The analysis results show that the C/O ratio of the unfunctionalized material MP is 4.89, while the C/O ratios of the functional materials MP-SO 3 H, MP-SO 3 H-HT, MP-COOH and MP-Oxy are 5.85. , 4.75, 3.72 and 3.32. MP-SO 3 H has a higher ratio because most of the functional groups are modified at the edges. As for MP-SO 3 H-HT, the C/O ratio of MP-SO 3 H-HT will decrease because the hydroxyl group will replace the sulfonated group after hydrothermal treatment. The functional groups of MP-COOH and MP-Oxy are not only modified at the edges of the material, but also partially modified on the benzene ring, resulting in a lower C/O ratio.
拉曼光譜Raman spectroscopy
於拉曼光譜分析中,分別於1360 cm -1及1585 cm -1處觀察到D譜帶及G譜帶,如圖7所示。 1360 cm -1處的D譜帶表示有結構缺陷(sp 3)引起的平面外振動,而1585 cm -1處的G譜帶則指sp 2鍵結之碳原子平面內振動。 分析結果顯示,非官能性材料MP的I D/I G比值為0.83,而MP-SO 3H(0.74)和MP-SO 3H-HT(0.88)的I D/I G比值低於MP-COOH(0.96)及MP-Oxy(0.97)的I D/ I G比值。 因此,可確認MP-SO 3H和MP-SO 3H-HT在邊緣上具有比MP-COOH及MP-Oxy更多的官能基。 In the Raman spectroscopy analysis, the D band and G band were observed at 1360 cm -1 and 1585 cm -1 respectively, as shown in Figure 7. The D band at 1360 cm -1 represents out-of-plane vibration caused by structural defects (sp 3 ), while the G band at 1585 cm -1 refers to the in-plane vibration of sp 2 bonded carbon atoms. Analysis showed that non-functional material MP, I D / I G ratio of 0.83, and the MP-SO 3 H (0.74) and MP-SO 3 H-HT ( 0.88) of the I D / I G ratio is below MP- I D / I G ratio of COOH (0.96) and MP-Oxy (0.97). Therefore, it can be confirmed that MP-SO 3 H and MP-SO 3 H-HT have more functional groups on the edge than MP-COOH and MP-Oxy.
製備非晶相纖維素及預水解纖維素Preparation of amorphous cellulose and pre-hydrolyzed cellulose
首先於40mL濃HCl中潤濕5g市售微晶纖維素(Avicel® PH-101),然後再加入160mL冷HCl(先在乾冰浴中預冷卻1.5小時)溶解纖維素,以合成非晶相纖維素。將β-葡聚醣/ HCl溶液倒入1L冷丙酮中,以直接再沉澱成蓬鬆的白色固體,或在室溫下溶解2小時後進行再沉澱(預水解纖維素)。接著,在4℃下以15,000 rpm超離心15分鐘以進行分離,並重覆三次。於離心過程中,用冷丙酮洗滌固體並儲存於低溫環境下,以降低纖維素水解產生不能用之短β-葡聚醣鏈的可能性。首先,將分離出的固體分散於1.5L冷去離子(DI)水中,然後用PTFE濾紙過濾出白色粉末,並用冷DI水洗滌至呈中性pH值。此外,合成出的非晶相纖維素以DI水進行索氏萃取24小時,接著冷凍乾燥3天。First wetting 5g of commercially available microcrystalline cellulose (Avicel® PH-101) in 40mL concentrated HCl, and then adding 160mL cold HCl (pre-cooled in a dry ice bath for 1.5 hours) to dissolve the cellulose to synthesize amorphous fiber Vegetarian. Pour the β-glucan/HCl solution into 1L cold acetone to directly re-precipitate into a fluffy white solid, or dissolve it at room temperature for 2 hours and then re-precipitate (pre-hydrolyzed cellulose). Next, the separation was performed by ultracentrifugation at 15,000 rpm at 4°C for 15 minutes, and repeated three times. During the centrifugation process, the solid was washed with cold acetone and stored at a low temperature to reduce the possibility of unusable short β-glucan chains produced by cellulose hydrolysis. First, disperse the separated solid in 1.5L cold deionized (DI) water, then filter the white powder with PTFE filter paper, and wash it with cold DI water to a neutral pH. In addition, the synthesized amorphous cellulose was subjected to Soxhlet extraction with DI water for 24 hours, and then freeze-dried for 3 days.
纖維素水解Cellulose hydrolysis
纖維素水解:選擇市售微晶纖維素(Avicel ®PH-101)、非晶相纖維素或預水解纖維素(50 mg)進行水解降解,其使用(i)非均相催化劑:MP或官能性MP(5 mg)、MCN-HSO 3(5mg)、市售強酸樹脂Amberlyst 15(5mg)或Nafion 50(球粒約40mg)於去離子水溶液(2mL)中;或(ii)均相硫酸水溶液(7.5mN,2mL)。將所得懸浮溶液置於專用高壓玻璃管(外徑:1.9cm,長度:6.0cm)中,其含有磁石。將管置於預熱之加熱板塊中,以400 rpm攪拌,並於自生壓力下以130、150或180℃處理2、3、4、12、24或48小時。於反應後,將高壓玻璃管從加熱板塊上取下進行冷卻。使用SPE過濾組(200mg / 3mL SPE管柱,二氧化矽)分別收集混合物及濾液,隨後用75℃水(8mL)洗滌過濾的混合物,以將殘留的醣或衍生物完全洗到預稱重的15毫升聚丙烯管中。濾液的體積(Vfiltrate)係以過濾前後的管質量差值除以水密度(1g / cm 3)(Vfiltrate =(Mfull-Mempty)/(1 g / cm 3); empty:空管質量;Mfull:過濾後的管質量)算得。通過HPLC表徵濾液濃度,以估算反應產生的產物及轉化的纖維素重量百分比。控制組實驗除未加入催化劑外,其反應條件皆與上述相同。 Cellulose hydrolysis: choose commercially available microcrystalline cellulose (Avicel ® PH-101), amorphous cellulose or pre-hydrolyzed cellulose (50 mg) for hydrolytic degradation, using (i) heterogeneous catalyst: MP or functional Reactive MP (5 mg), MCN-HSO 3 (5 mg), commercially available strong acid resin Amberlyst 15 (5 mg) or Nafion 50 (about 40 mg pellets) in deionized aqueous solution (2 mL); or (ii) homogeneous aqueous sulfuric acid (7.5mN, 2mL). The resulting suspension solution was placed in a special high-pressure glass tube (outer diameter: 1.9 cm, length: 6.0 cm), which contained a magnet. Place the tube in a preheated heating plate, stir at 400 rpm, and treat at 130, 150 or 180°C for 2, 3, 4, 12, 24 or 48 hours under autogenous pressure. After the reaction, the high-pressure glass tube was removed from the heating plate for cooling. Use the SPE filter set (200mg / 3mL SPE column, silica) to collect the mixture and filtrate, and then wash the filtered mixture with 75℃ water (8mL) to completely wash the residual sugars or derivatives to the pre-weighed 15 ml polypropylene tube. The volume of the filtrate (Vfiltrate) is the difference in tube mass before and after filtration divided by the water density (1g / cm 3 ) (Vfiltrate = (Mfull-Mempty)/(1 g / cm 3 ); empty: empty tube mass; Mfull: The mass of the filtered tube) is calculated. The concentration of the filtrate was characterized by HPLC to estimate the product produced by the reaction and the weight percentage of the converted cellulose. The reaction conditions of the control group experiment were the same as the above except that no catalyst was added.
三種不同類型的纖維素(50 mg之結晶相纖維素、非晶相纖維素及預水解纖維素)與官能化MP(5 mg之MP-SO 3H、MP-SO 3H-HT、MP-COOH及MP-Oxy)的水解降解結果示於圖8至圖13中。該些材料與三種纖維素在2mL水溶液中以180℃反應2、3及4小時。結果顯示,水解後得到三種產物:纖維二糖(cellobiose)、葡萄糖(glucose)和羥甲基糠醛(Hydroxymethyl Furfural,簡稱HMF),葡萄糖是水解後的主要產物。因此,發現MP-COOH由於其酸位點密度相對較低而具有較低的葡萄糖產率,而MP-SO 3H及MP-SO 3H-HT有較多的酸位點,其強酸性官能基集中在材料邊緣,因而促進糖苷鍵的裂解。尤其,MP-SO 3H在180℃下與預水解纖維素反應3小時,可獲得44%之最高葡萄糖產率。隨著反應時間的增加,只有MP-Oxy有更高的葡萄糖產率。 Three different types of cellulose (50 mg of crystalline phase cellulose, amorphous phase cellulose and pre-hydrolyzed cellulose) and functionalized MP (5 mg of MP-SO 3 H, MP-SO 3 H-HT, MP- The hydrolytic degradation results of COOH and MP-Oxy) are shown in Figure 8 to Figure 13. These materials and three celluloses were reacted at 180°C for 2, 3, and 4 hours in 2 mL of aqueous solution. The results showed that three products were obtained after hydrolysis: cellobiose, glucose and Hydroxymethyl Furfural (HMF). Glucose is the main product after hydrolysis. Therefore, it is found that MP-COOH has a lower glucose yield due to its relatively low density of acid sites, while MP-SO 3 H and MP-SO 3 H-HT have more acid sites and their strong acidic functions The base is concentrated on the edge of the material, thus promoting the cleavage of glycosidic bonds. In particular, MP-SO 3 H reacted with pre-hydrolyzed cellulose at 180°C for 3 hours to obtain the highest glucose yield of 44%. As the reaction time increases, only MP-Oxy has a higher glucose yield.
浸出( leaching)測試 Leaching (leaching) test
首先,將3 mL去離子水加到反應管中之7.5 mg MP系列催化劑,並在180℃下加熱反應管3小時。 於反應後,用0.22 μm PTFE針筒過濾器(Syringe filter)過濾溶液,並將2 mL澄清濾液加到另一反應管中的50 mg纖維素,以與第一反應管相同的對應溫度及時間處理第二反應管。First, add 3 mL of deionized water to the 7.5 mg MP series catalyst in the reaction tube, and heat the reaction tube at 180°C for 3 hours. After the reaction, filter the solution with a 0.22 μm PTFE Syringe filter, and add 2 mL of the clear filtrate to the 50 mg cellulose in the other reaction tube at the same temperature and time as the first reaction tube Dispose of the second reaction tube.
非晶相纖維素與不同催化劑於180℃下進行3小時浸出測試,其結果示於圖14中。可看出MP-SO 3H、MP-SO 3H-HT及MP-COOH浸出所造成之葡萄糖產率分別為2.3 %、0.5 %及0.3 %。該些材料酸浸出所引起的葡萄糖產量非常低,此表示纖維素水解主要是由官能性MP系列材料邊緣上的酸性官能基團所導致,而MP-Oxy材料酸浸出所引起的葡萄糖產率高達39%。 The amorphous phase cellulose and different catalysts were subjected to a 3-hour leaching test at 180°C. The results are shown in FIG. 14. It can be seen that the glucose yields caused by MP-SO 3 H, MP-SO 3 H-HT and MP-COOH leaching are 2.3%, 0.5% and 0.3%, respectively. The glucose yield caused by acid leaching of these materials is very low, which means that the hydrolysis of cellulose is mainly caused by the acidic functional groups on the edges of functional MP series materials, while the glucose yield caused by acid leaching of MP-Oxy materials is as high as 39%.
與其他催化劑比較纖維素水解效率Compare cellulose hydrolysis efficiency with other catalysts
比較MP系列催化劑與其他材料(例如Amberlyst
®15氫型(5 mg)或Nafion
®NR50(珠粒約40 mg)市售強酸性樹脂、磺化中孔碳奈米粒子(MCN-SO
3H)及均相硫酸水溶液(7.5 mN,2 mL))之纖維素水解效率,如圖15所示。結果顯示,以Amberlyst 15作為催化劑以180℃進行3小時之非晶相纖維素水解反應可得到約9.5%之葡萄糖產率,而Nafion 50作為催化劑的產率僅約5.9%。儘管該些市售的非均相催化劑在表面上有強酸基團可引起纖維素之高水解效率,但其表面上的酸性基團位置可能非常遠。因此,雖然Amberlyst 15及Nafion 50的浸出測試分別得到2.5%及0.4%的葡萄糖產率,但官能性MP之葡萄糖產量可高3倍。另一方面,非均相催化劑MCN-SO
3H作為催化劑可獲得6.9%的葡萄糖產率。此低葡萄糖產率可歸因於多孔通道內較低的酸表面覆蓋率,甚至導致有0.6%的葡萄糖產率係由材料浸出所引起。至於與MP-SO
3H具有相同酸量的均相硫酸水溶液,其均相反應的水解效率比MP-SO
3H低一半。據推測,於相同的水溶液中,MP-SO
3H具有高的酸表面覆蓋率,此能夠更有效地破壞纖維素中的糖苷鍵。
Compare MP series catalysts with other materials (such as
上述實施例透過化學氧化方法合成出一系列具有酸性官能基高表面覆蓋率之介相瀝青(MP)系列材料,其包括MP-SO 3H(用硫酸處理)、MP-SO 3H-HT(水熱處理MP-SO 3H)、MP-COOH(用硝酸處理)及MP-Oxy(用次氯酸鈉處理)。酸鹼反式滴定結果顯示,MP-SO 3H具有最高的酸位點密度(3.1 mmol / g),其含有1.5 mmol / g之主要磺酸及0.84 mmol / g 內酯。水熱處理後,MP-SO 3H-HT之磺酸基團減少,且產生更多的苯酚。氮氣吸附分析顯示官能性MP的比表面積低於56 m 2/ g,此表示該些材料為非孔洞結構。 MP上靠近的弱酸分子可仿纖維素水解酶(其活性中心具有靠近的羧基),可作為纖維素水解之替代觸媒。令人驚訝的是, MP-SO 3H可觀察到最高的CO 2吸附量(2.46 mmol / g),其可具有非常大的CO 2封存潛力,故可作為捕集二氧化碳之無孔洞的酸官能基化吸附劑。 In the above embodiments, a series of mesophase pitch (MP) materials with acidic functional groups and high surface coverage were synthesized through chemical oxidation methods, including MP-SO 3 H (treated with sulfuric acid), MP-SO 3 H-HT ( Hydrothermal treatment of MP-SO 3 H), MP-COOH (treated with nitric acid) and MP-Oxy (treated with sodium hypochlorite). Acid-base trans titration results show that MP-SO 3 H has the highest acid site density (3.1 mmol/g), and it contains 1.5 mmol/g of main sulfonic acid and 0.84 mmol/g of lactone. After the hydrothermal treatment, the sulfonic acid groups of MP-SO 3 H-HT are reduced and more phenol is produced. Nitrogen adsorption analysis showed that the specific surface area of the functional MP is less than 56 m 2 /g, which indicates that these materials have a non-porous structure. The weak acid molecules close to MP can imitate cellulose hydrolase (its active center has close carboxyl groups) and can be used as an alternative catalyst for cellulose hydrolysis. Surprisingly, MP-SO 3 H can observe the highest CO 2 adsorption capacity (2.46 mmol/g). It has a very large CO 2 storage potential, so it can be used as a non-porous acid function for capturing carbon dioxide. Base adsorbent.
上述實施例係為了說明本發明之具體實施方式及其技術特徵,而不是用於限制本發明之保護範疇。 在不悖離隨附申請專利範圍所請之發明精神及範疇下,可進行許多其他可能的修改及變化。本發明所主張之權利範圍自應以申請專利範圍所述為準。The above-mentioned embodiments are intended to illustrate the specific implementation and technical features of the present invention, rather than to limit the protection scope of the present invention. Many other possible modifications and changes can be made without departing from the spirit and scope of the invention requested in the scope of the attached patent application. The scope of the rights claimed in the present invention should be subject to the scope of the patent application.
無no
圖1及2為MP系列材料之氮氣等溫吸附曲線圖; 圖3為MP系列材料之二氧化碳氣體等溫吸附曲線圖; 圖4為MP系列材料之FTIR光譜圖; 圖5為MP系列材料之固態NMR分析圖; 圖6為MP系列材料之XPS分析圖; 圖7為MP系列材料之拉曼分析圖; 圖8為官能性MP系列材料用於結晶相纖維素水解2小時的總產量; 圖9為官能性MP系列材料用於結晶相纖維素水解3小時的總產量; 圖10為官能性MP系列材料用於結晶相纖維素水解4小時的總產量; 圖11為官能性MP系列材料用於非晶相纖維素水解3小時的總產量; 圖12為官能性MP系列材料用於非晶相纖維素水解4小時的總產量; 圖13為官能性MP系列材料用於預水解纖維素水解3小時的總產量; 圖14為官能性MP系列材料於180°C下進行3小時非晶相纖維素之浸出測試;以及 圖15為官能性MP系列材料、H 2SO 4、Amberlyst 15、Nafion 50 及MCN-HSO 3之纖維素水解效率。 Figures 1 and 2 are the nitrogen isotherm adsorption curves of MP series materials; Figure 3 is the carbon dioxide gas adsorption isotherm curves of MP series materials; Figure 4 is the FTIR spectrum of MP series materials; Figure 5 is the solid state of MP series materials NMR analysis chart; Fig. 6 is the XPS analysis chart of MP series materials; Fig. 7 is the Raman analysis chart of MP series materials; Fig. 8 is the total yield of functional MP series materials used in crystalline phase cellulose hydrolysis for 2 hours; Fig. 9 Is the total output of functional MP series materials used in crystalline phase cellulose hydrolysis for 3 hours; Figure 10 is the total output of functional MP series materials used in crystalline phase cellulose hydrolysis for 4 hours; Figure 11 is the total output of functional MP series materials used in crystalline phase cellulose hydrolysis The total yield of amorphous cellulose hydrolysis for 3 hours; Figure 12 shows the total yield of functional MP series materials used in amorphous cellulose hydrolysis for 4 hours; Figure 13 shows the functional MP series materials used for pre-hydrolyzed cellulose hydrolysis 3 Hours of total output; Figure 14 shows the leaching test of amorphous cellulose with functional MP series materials at 180°C for 3 hours; and Figure 15 shows functional MP series materials, H 2 SO 4 , Amberlyst 15, Nafion 50 And MCN-HSO 3 cellulose hydrolysis efficiency.
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