SO₄^2-/M_xO_y固体超强酸及γ-Al₂O₃-NaOH-Na固体超强碱的应用研究

【作者】 李修刚；

【导师】 赵斌； 高根之；

【作者基本信息】 曲阜师范大学 ， 有机化学， 2008， 硕士

【摘要】 酸碱催化是催化领域的一个重要组成部分，尤其是近年来兴起的固体超强酸与固体超强碱，因其具有很高的酸碱强度，催化效率高，无环境污染，不腐蚀设备以及可重复使用和再生等优点，日益受到广大科学工作者的关注。SO₄^2-/M_xO_y型固体超强酸和γ-Al₂O₃-NaOH-Na型固体超强碱是其中最具代表性、最有工业应用前景的催化剂，本文对两种催化剂及其在有机合成中的应用进行了研究。本文第一部分，对近年固体超强酸的发展进行了综述，在此基础上，对专利“一种颗粒型固体超强酸催化剂及制备方法”中提及的固体超强酸进行了酸强度、TEM、FT-IR、孔隙及比表面表征，测定了固体超强酸表面硫酸根分解产物，对固体超强酸的表面结构进行了推测，实验结果表明：该专利固体超强酸的酸强度H₀≤-16．04，为的10000倍以上（100％硫酸酸强度H₀=-11．99），粉末催化剂比表面为198m²/g，平均孔径为36（?），颗粒催化剂比表面为224 m²／g，平均孔径为82 （?），比表面均较原载体氧化铝有所减少，但SEM表征表明，该固体超强酸仍保留有较大的孔道结构。固体超强酸的催化活性是酸强度、晶型、比表面积、表面孔结构共同作用的结果，具备高酸强度、微晶结构，大比表面积以及孔容的SO₄^2-／M_xO_y型固体超强酸具有较好的催化活性；SO₄^2-／M_xO_y型固体超强酸存在桥式双配态和螯合双配态两种结构，其中桥式双配态结构分解时脱SO₃，螯合双配态结构分解时脱SO₂，低浓度硫酸（≤2．5mol／L）负载时，硫酸根主要以螯合双配位态形式存在，螯合双配位态结构对催化剂催化活性贡献较大。同时将该催化剂应用于合成多元醇缩酮、1，4-二氧六环、季戊四醇油酸酯的反应，该催化剂在上述反应中表现出了良好的催化活性：催化剂用量在原料总质量的6-8％之间，采用二甲苯或酮本身带水，在带水剂回流条件下，反应均能在3h内进行完全，反应收率均在90％以上，经GC／MS分析表明，副反应主要为醇自身环化脱水，因此控制一定的反应温度与醇酮摩尔比是必要的，本文合成了季戊四醇双缩环己酮、苯乙酮1，2-丙二醇缩酮、环己酮乙二醇缩酮、苯乙酮乙二醇缩酮四种多元醇缩酮化合物；以廉价二甘醇为原料，采用气相常压固定床催化，反应温度为260℃，进料速度为0．4ml／min条件下，1，4-二氧六环的最高产率可达到76．14％；以季戊四醇和高级脂肪酸为原料，采用三甲苯为带水剂，高级脂肪酸与季戊四醇的摩尔比为5．6：1，固体超强酸催化剂用量为原料总质量的0．90％，催化温度为180℃，反应4小时，季戊四醇高级脂肪酸酯的酯化率可达99．88％。固体超强酸催化工艺具有催化效率高、不腐蚀设备、无环境污染、催化剂可重复使用和再生的优点，是工业酸催化工艺的理想选择。本文第二部分，总结了固体超强碱类催化剂近年的发展，对固体超强碱类催化剂未能工业化的原因进行了解释，由于制备固体超强碱一般采用金属氢氧化物或碳酸盐分解的方法，无法得到较大的比表面和孔结构的催化剂，因此催化活性一般不高，增大固体超强碱催化剂的比表面积和有效孔径是对固体超强碱类催化剂进行改性的重要内容。在此基础上，对传统固体超强碱γ-Al₂O₃-NaOH-Na的制备工艺进行了改进，改变了固体超强碱传统制备工艺，即金属碳酸盐或氢氧化物分解的方法，采用成型的大孔容及比表面积的γ-Al₂O₃载体，将碱及碱金属负载于载体之上，优化制备条件，得到了具有优良催化活性的固体超强碱催化剂，同时用BET、IR、TEM以及XRD等多种表征方对新制备的固体超强碱催化剂进行表征，结果表明所制备的固体超强碱碱强度H₀≥37，与传统工艺制备的同类型固体超强碱相当，比表面积为142．52m²．g^-1，孔容为0．4ml／g，较原γ-Al₂O₃载体有所减少，但通过SEM与TEM表征说明该固体超强碱仍保留了原载体的孔道结构，其整体催化效果优于传统制备方法所制备的固体超强碱催化剂。将该固体超强碱催化剂应用于查尔酮、环己酮自缩合以及生物柴油的合成反应中，该改性固体超强碱催化剂表现出了良好的催化活性：以苯乙酮和苯甲醛为原料，反应温度为40℃，催化剂用量为反应物总质量的7．5％，苯甲醛与苯乙酮摩尔比为1：1．1，反应3h查尔酮产率可达96．88％；以环已酮为原料，催化剂用量为原料总质量的10％，反应温度为190℃，反应3h，二聚物的总收率可达85．66％；以动物油和甲醇为原料，醇油摩尔为9：1，催化剂用量为动物油质量的2％，反应温度为70℃，反应3h后，生物柴油的收率可达91．8％。固体超强碱催化工艺催化效率高、无环境污染、不腐蚀设备，具有一定的工业应用前景。更多还原

【Abstract】 Acid-base catalysis is an important part of catalysis fields. Solid superacid and solid superbase, which are developed in resent years, attract close attention of many researchers, because of high acidic and basic strength, high catalysis efficiency, no pollution to environment, and no corrosion to equipments, reusable and renewable property. SO₄^2-/M_xO_y solid superacid andγ-Al₂O₃-NaOH-Na solid superbase are most representative and industrial valuable ones of acid-base catalysts. In this paper application of these two catalysts in organic synthesis was studied.The first part of this paper provides an overview of the development of solid superacid in resent years. The catalyst, which is involved in Chinese patent ’A granular solid superacid catalyst and the method of preparation’, was characterized by the method of indicator, SEM, FT-IR and BET. The decomposition product of sulfate radical on the surface of catalyst was analyzed in order to determine the surface structure of solid superacid catalyst. The result of experiments shows that the acid strength H₀≤-16.04, 10000 times of 100% H₂SO₄ （H₀=-11.99）, specific surface of powdery catalyst 198m²/g and average pore radii 36℃, specific surface of granule catalyst 224m²/g and average pore radii 82℃which is smaller than the carrier Al₂O 3. The catalyst, which has high, microcrystalline structure, large and specific pore volume, has high catalytic activity. There are two kinds of structures in SO₄^2-/M_xO_y solid superacid: the bridge type double co-ordinating structure and the chelate type double co-ordinating structure, the bridge type double co-ordinating structure giving SO₃, the chelate type double co-ordinating structure giving SO₂. The chelate type double co-ordinating structure plays more important part in catalytic activity.For the synthesis reaction of polylol ketal,1,4-dioxane, pentaerythritol fatty acid ester, SO₄^2-/M_xO_y solid superacid has a satisfactory catalytic activity. With the catalyst amount wt% of raw material, after 3 hour, the yields of all can be over 90%, and the side reaction is dehydratio of polyol. Four polylol ketal cyclohexanone pentaerythritol ketal, acetophenone 1,2-propanediol ketal, cylohexanone ethylene ketal, acetophenone ethylene ketal were synthesized in this paper. With diglycol as raw material, reaction temperature 260 ?, feed ratio 0.4ml/min, 1,4-dioxane was synthesized in fixed bed reactor, and the yield can be up to 76.14%. With pentaerythritol and fatty acid as raw materia, mole ratio of fatty acid and pentaerythritol 5.6:1, catalyst amount 0.90% wt% of totle material, catalysis temperature 180?, after four hours, yield of pentaerythritol fatty acid ester can be up to 99.88%. Because of high catalytic activity, no corrosion to equipments, no pollution to environment, reusable and renewable catalyst, the methodology of solid superacid is the optimal choice of acidic catalytic reaction.In the second part of this paper, the development of solid superbase was summerized. Based on traditional solid superbaseγ-Al₂O₃-NaOH-Na,γ-Al₂O₃ carrier with large specific surface and specific pore volume was introduced in order to improve traditional preparation methodology, which uses carbonate and hydroxide as precusor. The catalyst, which has high catalytic activity, was obtained and characterized by the method of BET, FT-IR, SEM, XRD and so on. The result shows that the catalyst has higher catalytic activity than traditional solid superbaseγ-Al₂O₃-NaOH-Na, H₀≥37, specific surface 142.52m².g^-1, specific pore volume 0.4ml/g. For the synthesis reaction of chalcone, cyclohexanone aldolization and biodiesel,γ-Al₂O₃-NaOH-Na solid superacid has a satisfactory catalytic activity. With hypnone and phenylaldehyde as raw material, amount of catalyst 7.5% wt% of material, mole ratio of hypnone and phenylaldehyde 1:1.1, reaction temperature 40℃, after 3 hours, the yield of chalcone can be up to 96.88%. With cyclohexanone as raw material, amount of catalyst 10% wt% of material, reaction temperature 190℃, after 3 hours, dimmer of cyclohexanone can be up to 85.66%. With animal oil and mathanol as raw material, mole ratio of mathanol and oil 9:1, amount of catalyst 2% wt% of oil, reaction temperature 70℃, after 3 hours, the yield of biodiesel can be up to 91.8%. The methodology of solid superbase has some industrial prospects, because of high catalytic activity, no corrosion to equipments, and no pollution to environment.更多还原