負(fù)載型雙功能磁性催化劑的制備及性能研究
發(fā)布時(shí)間：2019-05-23 17:49
【摘要】：甲醇作為一種重要的碳一化工原料,近些年來出現(xiàn)了產(chǎn)量過剩的現(xiàn)象,以甲醇為原料制備下游產(chǎn)品受到廣泛研究。其中甲酸甲酯(MF)是甲醇下游產(chǎn)品中一種非常重要的有機(jī)中間體,不僅可以直接用作干水果、谷物等的煙熏劑和殺菌劑,還可以用作有機(jī)溶劑和藥物合成的原料,應(yīng)用范圍非常廣泛。作為非均相反應(yīng)體系中具有很大的發(fā)展前景的催化劑載體,介孔材料具有易調(diào)控的孔結(jié)構(gòu)和高地吸附能力,在催化等方面含有廣闊的發(fā)展前景。特別是將介孔材料和磁性Fe304相結(jié)合所制得的復(fù)合磁性催化劑載體。這種復(fù)合材料不僅具有便于回收分離的特性,而且還保持著介孔材料本身的特點(diǎn)。本文對(duì)甲醇液相一步催化轉(zhuǎn)化制備甲酸甲酯反應(yīng)體系的雙功能催化劑進(jìn)行了研究。本論文首先通過焙燒擬薄水鋁石制備γ-A1203載體,并用浸漬-還原法把貴金屬Au、Pd負(fù)載在了 γ-Al2O3載體上,制備了單金屬納米顆粒的Au/γ-Al2O3,Pd/γ-Al2O3和雙金屬Pd-Au/γ-Al203催化劑;另外還通過異丙醇鋁水解在磁核Fe304外包覆了 γ-A1203,制備了磁性Pd/γ-Al2O3@ Fe3O4雙功能催化劑,對(duì)催化劑進(jìn)行了XRD、XPS、BET、NH3-TPD、H2-TPR、TEM等一系列表征,并測(cè)定了其在甲醇液相催化制備甲酸甲酯反應(yīng)過程中的催化性能。實(shí)驗(yàn)結(jié)果如下:(1)將Au納米顆粒負(fù)載在y-A1203載體上制備的一系列Au/γ-Al2O3催化劑,其比表面積和孔體積分別為353.5 m2·g-1和1.53cm3·g-1,Au納米顆粒分布比較均勻,平均粒徑約5.0 nm,但是該催化劑在甲醇液相催化反應(yīng)中的催化效果不是很理想。在負(fù)載量為1.0wt%,5 mL無水甲醇、0.8 MPa氧氣壓力,130℃反應(yīng)6 h時(shí),甲醇轉(zhuǎn)化率最高達(dá)到28.5%,甲酸甲酯選擇性37.15%,收率10.59%。在Au催化劑中加入適宜比例的Pd制備的雙金屬Pd-Au/γ-Al2O3催化劑在甲醇液相催化轉(zhuǎn)化生成甲酸甲酯反應(yīng)體系中的催化活性和MF選擇性明顯比Au/γ-Al2O3催化劑高,該催化劑的比表面積和孔體積分別為332.7 m2·g-1和1.14 cm3·g-1,負(fù)載的貴金屬納米顆粒粒徑在2～5 nm,而且該催化劑的酸性和氧化性與單金屬Au/γ-Al2O3催化劑相比有明顯提高。該催化劑在甲醇液相一步催化轉(zhuǎn)化制備甲酸甲酯反應(yīng)過程中的最佳反應(yīng)條件為:反應(yīng)溫度160℃,氧氣壓力0.8 MPa,反應(yīng)時(shí)間6 h時(shí),甲醇轉(zhuǎn)化率和甲酸甲酯選擇性分別為53.47%和58.45%,收率31.25%。(2)用同樣方法制備的Pd/γ-Al203催化劑與Au/γ-Al2O3催化劑相比催化活性有了明顯的提高,氧化性與酸性都比Au/γ-Al2O3催化劑高,Pd納米顆粒粒徑平均約為5.0 nm。通過優(yōu)化反應(yīng)條件,甲醇轉(zhuǎn)化率可以達(dá)到47.17%,甲酸甲酯選擇性也可達(dá)到41.83%,收率19.73%。同時(shí),還利用異丙醇鋁水解制備了磁性雙功能Pd/γ-Al2O3@Fe3O4催化劑,并對(duì)其進(jìn)行了 XRD和VSM表征,結(jié)果表明,該催化劑具有良好的超順磁性,且保持著γ-Al2O3和Fe3O4的特征衍射峰。其在最優(yōu)反應(yīng)條件下甲醇轉(zhuǎn)化率和甲酸甲酯選擇性分別為46.87%和40.79%,收率19.11%,催化性能與Pd/γ-Al2O3催化劑相比沒有明顯變化,但是其重復(fù)使用性能明顯提高。
[Abstract]:As a kind of important carbon-chemical raw material, methanol has the phenomenon of excess production in recent years, and the preparation of the downstream products with methanol as the raw material is widely studied. The methyl formate (MF) is a very important organic intermediate in the downstream product of methanol, not only can be used as a fumigant and a bactericide for dry fruits, grains and the like, but also can be used as a raw material for organic solvent and drug synthesis, and the application range is very wide. As a catalyst carrier with great development prospect in the heterogeneous reaction system, the mesoporous material has an easily-regulated pore structure and high adsorption capacity, and has wide development prospect in the aspects of catalysis and the like. In particular to a composite magnetic catalyst carrier prepared by combining a mesoporous material and a magnetic Fe304. The composite material not only has the characteristics of convenient recovery and separation, but also maintains the characteristics of the mesoporous material itself. In this paper, a double-functional catalyst for preparing methyl formate reaction system by one-step catalytic conversion of methanol is studied. The Au/ Al-Al2O3, Pd/ Al-Al2O3 and the bimetallic Pd-Au/ Al-Al203 catalyst of the single-metal nanoparticles were prepared by roasting the pseudo-boehmite to prepare the Al-Al 203 carrier, and loading the noble metal Au and Pd on the Al-Al2O3 carrier by a dip-reduction method. A series of characteristics such as XRD, XPS, BET, NH3-TPD, H2-TPR, TEM and the like of the magnetic Pd/ Al-Al2O3 @ Fe3O4 double-functional catalyst are prepared by the hydrolysis of aluminum isopropoxide on the magnetic core Fe304, and the magnetic Pd/ Al-Al2O3 @ Fe3O4 double-functional catalyst is prepared. And the catalytic performance of the catalyst in the process of preparing the methyl formate by the liquid phase of the methanol is measured. The results of the experiment are as follows: (1) A series of Au/ I-Al2O3 catalysts prepared by loading Au nanoparticles on a y-A1203 carrier have a specific surface area and pore volume of 353.5 m2 路 g-1 and 1.53 cm3 路 g-1, and the distribution of Au nanoparticles is uniform, with an average particle size of about 5.0 nm. But the catalytic effect of the catalyst in the liquid-phase catalytic reaction of methanol is not ideal. The conversion of methanol was up to 28.5%, the selectivity of methyl formate was 37.15% and the yield was 10.59% when the loading was 1.0% by weight,5 mL of anhydrous methanol, 0.8 MPa of oxygen pressure and 130 鈩，
本文編號(hào)：2484096
[Abstract]:As a kind of important carbon-chemical raw material, methanol has the phenomenon of excess production in recent years, and the preparation of the downstream products with methanol as the raw material is widely studied. The methyl formate (MF) is a very important organic intermediate in the downstream product of methanol, not only can be used as a fumigant and a bactericide for dry fruits, grains and the like, but also can be used as a raw material for organic solvent and drug synthesis, and the application range is very wide. As a catalyst carrier with great development prospect in the heterogeneous reaction system, the mesoporous material has an easily-regulated pore structure and high adsorption capacity, and has wide development prospect in the aspects of catalysis and the like. In particular to a composite magnetic catalyst carrier prepared by combining a mesoporous material and a magnetic Fe304. The composite material not only has the characteristics of convenient recovery and separation, but also maintains the characteristics of the mesoporous material itself. In this paper, a double-functional catalyst for preparing methyl formate reaction system by one-step catalytic conversion of methanol is studied. The Au/ Al-Al2O3, Pd/ Al-Al2O3 and the bimetallic Pd-Au/ Al-Al203 catalyst of the single-metal nanoparticles were prepared by roasting the pseudo-boehmite to prepare the Al-Al 203 carrier, and loading the noble metal Au and Pd on the Al-Al2O3 carrier by a dip-reduction method. A series of characteristics such as XRD, XPS, BET, NH3-TPD, H2-TPR, TEM and the like of the magnetic Pd/ Al-Al2O3 @ Fe3O4 double-functional catalyst are prepared by the hydrolysis of aluminum isopropoxide on the magnetic core Fe304, and the magnetic Pd/ Al-Al2O3 @ Fe3O4 double-functional catalyst is prepared. And the catalytic performance of the catalyst in the process of preparing the methyl formate by the liquid phase of the methanol is measured. The results of the experiment are as follows: (1) A series of Au/ I-Al2O3 catalysts prepared by loading Au nanoparticles on a y-A1203 carrier have a specific surface area and pore volume of 353.5 m2 路 g-1 and 1.53 cm3 路 g-1, and the distribution of Au nanoparticles is uniform, with an average particle size of about 5.0 nm. But the catalytic effect of the catalyst in the liquid-phase catalytic reaction of methanol is not ideal. The conversion of methanol was up to 28.5%, the selectivity of methyl formate was 37.15% and the yield was 10.59% when the loading was 1.0% by weight,5 mL of anhydrous methanol, 0.8 MPa of oxygen pressure and 130 鈩，
本文編號(hào)：2484096
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