【摘要】：以甲醇和二氧化碳為原料合成碳酸二甲酯是一條極具吸引力的工藝路線,同時解決了二氧化碳的去向和甲醇產(chǎn)能過剩的問題。具有Ia3d立方結(jié)構(gòu)的MCM-48因具有三維網(wǎng)狀結(jié)構(gòu)和良好的擴(kuò)散性能在催化領(lǐng)域具有較大的應(yīng)用潛質(zhì),但本身缺乏活性中心,限制了其應(yīng)用。本文將該反應(yīng)體系和材料的優(yōu)勢結(jié)合起來,將銅鎳金屬摻雜到MCM-48介孔分子篩中作為催化甲醇和二氧化碳直接合成碳酸二甲酯的催化劑。因氟離子具有提高分子篩水熱穩(wěn)定性的特點(diǎn),本文在含氟體系、較低的模板劑濃度下合成介孔分子篩MCM-48,研究了模板劑用量、水量、晶化溫度等對分子篩結(jié)構(gòu)的影響,并通過X射線衍射、電子掃描電鏡、透射電鏡、N2等溫吸附等方法對樣品進(jìn)行表征分析來確定合成分子篩的最優(yōu)制備條件,結(jié)果表明,當(dāng)模板劑用量、水量、晶化溫度分別為n(Si)：n(十六烷基三甲基溴化銨,簡寫為CTAB)=1:0.2、n(Si):n(H2O)=1:70、150 ℃時合成出的分子篩結(jié)構(gòu)和形貌最好。在最優(yōu)的分子篩合成條件下,分別通過水熱直接合成法和傳統(tǒng)浸漬法將金屬銅或鎳引入分子篩,考察了金屬摻雜量、單雙金屬摻雜、雙金屬摻雜時金屬摩爾比等對分子篩結(jié)構(gòu)的影響,并通過X射線衍射、紅外光譜、電感耦合等離子發(fā)射光譜、N2等溫吸附等方法對樣品進(jìn)行表征分析,結(jié)果表明,在一定的金屬摻雜范圍內(nèi)都可以成功制備出維持有三維有序性結(jié)構(gòu)的分子篩。水熱合成時,單金屬銅鎳的最大摻雜量分別可以達(dá)到n(Si)：n(Cu)=1：0.025、n(Si)：n(Ni)=1：0.030,銅鎳雙金屬的最大摻雜量可達(dá)n(Si)：n(Cu)：n(Ni)=1：0.02：0.01；浸漬合成時,氧化銅和氧化鎳的質(zhì)量分?jǐn)?shù)最大可達(dá)15%。采用Cahn-2000型高真空電子天平測試系統(tǒng)來研究水熱合成的樣品對二氧化碳的吸附量,結(jié)果表明,當(dāng)單金屬摻雜時,樣品對二氧化碳的吸附量隨金屬含量的增多呈先增大后減小的趨勢,金屬摻雜量分別為n(Si)：n(Cu)=0.015、n(Si)：n(Ni)=0.015時樣品對二氧化碳的吸附量最大；當(dāng)固定銅鎳摩爾比為2的雙金屬摻雜時,樣品對二氧化碳的吸附量隨金屬含量的增多而減�。划�(dāng)金屬總量相同、不同金屬摩爾比時,樣品對二氧化碳吸附量的變化趨勢為：Vab(銅鎳摩爾比為2時的雙金屬摻雜)Vab(銅單金屬摻雜)Vab(鎳單金屬摻雜)Vab(銅鎳摩爾比為0.5和1時的雙金屬摻雜)。反應(yīng)條件為150℃、7.5 bar CO2、10 mL甲醇、9h時對樣品的催化性能進(jìn)行考察,結(jié)果表明,水熱合成的樣品Cu-Ni-MCM-48-0.010-0.005的催化性能最好；在最優(yōu)催化劑催化反應(yīng)時優(yōu)化反應(yīng)條件,在考察范圍內(nèi),反應(yīng)最佳溫度為160℃,反應(yīng)最佳壓力為10bar。
[Abstract]:The synthesis of dimethyl carbonate from methanol and carbon dioxide is an attractive process, and the problem of carbon dioxide fate and methanol overcapacity is solved at the same time. MCM-48 with Ia3D cubic structure has great application potential in catalytic field because of its three-dimensional network structure and good diffusion performance, but its application is limited by its lack of active center. In this paper, the advantages of the reaction system and materials are combined, and copper and nickel metals are doped into MCM-48 mesoporous molecular sieve as catalysts for the direct synthesis of dimethyl carbonate from methanol and carbon dioxide. In this paper, mesoporous molecular sieve MCM-48 was synthesized in fluorine system with low concentration of template. The effects of the amount of template agent, water content and crystallization temperature on the structure of molecular sieve were studied. X-ray diffraction, electron scanning electron microscope, transmission electron microscope and N _ 2 isothermal adsorption were used to characterize the samples to determine the optimum preparation conditions. The results showed that the optimum preparation conditions were obtained when the amount of template, water content, The structure and morphology of the molecular sieve synthesized at n (Si): n (cetyltrimethylammonium bromide, CTAB) 1: 0.2n (Si): n (H2O) 1: 70150 鈩，

本文編號：2127367