共查询到18条相似文献,搜索用时 156 毫秒
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采用等体积浸渍法制备了一系列氧化铝负载碱金属氟化物固体碱催化剂,用于甘油(丙三醇)与碳酸二甲酯酯交换反应合成碳酸甘油酯,其中KF/γ-Al2O3催化剂能够更好地促进碳酸甘油酯的生成。进一步考察了KF/γ-Al2O3催化剂的制备条件、反应条件对甘油与碳酸二甲酯酯交换反应的影响。当KF负载在γ-Al2O3的负载量为15%(质量分数,下同),于400℃焙烧5 h后制得固体碱催化剂,在n(碳酸二甲酯)∶n(甘油)=3∶1,反应温度80℃,反应时间1.5 h的条件下,甘油的转化率达96.1%,碳酸甘油酯选择性和收率分别达98.1%和94.3%。 相似文献
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《辽宁化工》2020,(5)
鸡蛋壳是一类产量巨大的废弃物,其主要成分是碳酸钙,可以作为碱性物质氧化钙的来源。将鸡蛋壳废弃物制成氧化钙碱性催化剂,能变废为宝,符合绿色化学理念。本文探究了基于鸡蛋壳催化剂的制备及碳酸甘油酯的合成,并通过FTIR、XRD、SEM/EDS和等对催化剂进行表征。发现以天然废弃物鸡蛋壳为原材料,加入白云石及滑石粉,煅烧温度1 250℃,在高温电炉中煅烧4 h所制备出的催化剂可用于碳酸甘油酯的合成,并具有良好的活性。该催化剂合成碳酸甘油酯的最优条件为:催化剂用量为5wt.%,碳酸二甲酯与甘油的摩尔比为3∶1,反应温度为80℃,反应时间为2h,转化率高达94.67%。但该催化剂在酯交换反应中稳定性较差,失活较快。 相似文献
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研究了碳酸二甲酯与2,2,6,6-四甲基哌啶醇的酯交换反应,得到了甲基(2,2,6,6-四甲基)哌啶基碳酸酯。考察了催化剂、反应时间、原料摩尔比等因素对反应的影响。实验结果表明:碳酸二甲酯与2,2,6,6-四甲基哌啶醇摩尔比为4.5∶1,催化剂氨基锂的用量为哌啶醇质量的0.3%、反应温度为90℃、不添加其它溶剂反应12 h条件下,反应收率为91.3%。 相似文献
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ZnO催化合成歧化松香甘油酯反应的研究 总被引:1,自引:0,他引:1
以歧化松香和甘油为原料,ZnO为催化剂,进行歧化松香甘油酯合成反应的研究。考察了原料配比、催化剂用量、反应温度、反应时间、搅拌速度及保护气种类对酯化反应进度的影响,确定了催化酯化合成歧化松香甘油酯的最佳工艺条件为:原料歧化松香与甘油的摩尔比2.0∶1.0、催化剂用量0.2%(以歧化松香计)、反应温度270℃、反应时间3.0 h、搅拌速度400 r/min、CO2作保护气。在线采样跟踪研究酯化反应的动力学实验数据,运用Eviews软件回归分析,确定不同温度下反应体系的动力学参数,其中反应级数为一级,阿累尼乌斯方程中指前因子为k0=1.372×104min-1和反应活化能为Ea=66.019 kJ.mol-1。 相似文献
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以活性炭、尿素和FeCl_3·6H_2O为原料得到Fe(OH)3,通过N2气氛还原得到磁核Fe_3O_4/C,随后将其置于CaCl_2与MgCl_2·6H2O溶液中超声分散,通过共沉淀法得到前驱体,焙烧制得磁性非均相固体碱催化剂(CaOMgO)@Fe_3O_4/C。对磁性非均相固体碱催化剂〔(CaO-MgO)@Fe_3O_4/C〕进行了磁滞回线、X射线衍射(XRD)、透射电镜(TEM)、CO_2-TPD及N_2的吸附-脱附(BET)测试。结果表明,CaO-MgO均匀地分散在磁核Fe_3O_4/C表面,催化剂在700℃有个强峰,具有较强的碱强度,磁化强度为23.8 emu/g,显示出较好的磁性。以碳酸二甲酯与甘油制备碳酸甘油酯作为探针反应,考察了(CaO-MgO)@Fe_3O_4/C催化剂的催化性能,得到在温度为85℃,n(碳酸二甲酯)∶n(甘油)=5∶1,催化剂用量为甘油质量的3%,反应时间为1 h的条件下,碳酸甘油酯的收率达到98.80%,甘油的转化率达到99.48%。催化剂重复使用6次后,碳酸甘油酯的收率为94.45%。 相似文献
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A new process, coupling reaction and azeotropic distillation was proposed for the synthesis of glycerol carbonate (GC) from glycerol (G) and dimethyl carbonate (DMC). The bench scale experimental investigation was systematically conducted for this new process. With calcium oxide (CaO) as the solid catalyst, the high yield of glycerol carbonate can be obtained at a low molar ratio of dimethyl carbonate to glycerol with the method of coupling reaction and azetropic distillation. The effect of azeotropic agents on glycerol carbonate yield was explored, and indicated that benzene was the most effective azeotropic agent. The effects of the process parameters, tower height, amount of added benzene, final temperature of tower bottom and reflux ratio were investigated. Glycerol carbonate yield can be as high as 98% under the conditions at molar ratio of dimethyl carbonate to glycerol 1:1, final temperature of tower bottom 85 °C, 1.5 mass ratio of added benzene to that in the azeotrope with methanol theoretically produced and reflux ratio 4. By continuously removing methanol from reaction system with the method of coupling reaction and azeotropic distillation, the yield of glycerol carbonate can be retained at high level using the recycled catalyst. 相似文献
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以三嵌段共聚物(EO-PO-EO)F127为结构导向剂,甲阶酚醛树脂为碳源,KF·2H2O为无机前驱体,用溶剂诱导挥发自组装的方法合成KF/C复合材料。采用XRD、BET和XPS等手段对合成的材料进行结构表征,并考察KF/C在甘油与碳酸二甲酯酯交换合成碳酸甘油酯反应中的性能,结果表明,在甘油加入量为0.184 6 g、碳酸二甲酯加入量为0.900 7 g、溶剂N,N-二甲基乙酰胺为5.426 g、催化剂KF/C加入量为0.1 g、反应温度100 ℃、反应时间2 h和搅拌速率600 r·min-1条件下,甘油转化率达98.5%,碳酸甘油酯选择性达99.8%,催化剂具有较好的循环使用性能。 相似文献
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采用浸渍法制备KF/MgCO3前体,经高温焙烧后获得了一系列KF/MgO固体碱催化剂,用于催化碳酸二甲酯(DMC)和甘油(GL)酯交换反应合成甘油碳酸酯(GC)。系统考察了KF负载量和焙烧温度对催化剂活性的影响,并通过X射线衍射、N2吸脱附等温线、扫描电子显微镜和哈米特酸碱滴定等一系列技术对催化剂的结构性能进行了表征。结果表明,当KF负载量为20%(质量分数)时,经550℃焙烧所获得的20%KF/MgO-550催化剂活性最高。经过反应工艺条件的优化,当催化剂与甘油的相对质量分数为2%,DMC与GL的摩尔比为3∶1,75℃条件下反应1.5h后,GC收率可以达到96.8%。当20%KF/MgO-550催化剂重复使用3次之后,GC的收率由96.8%降低到67.3%,经再生处理后20%KF/MgO-550的催化活性可以恢复并且表现出更优异的稳定性。 相似文献
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Synthesis of glycerol carbonate from glycerol and dimethyl carbonate by transesterification: Catalyst screening and reaction optimization 总被引:2,自引:0,他引:2
Jos R. Ochoa-Gmez Olga Gmez-Jimnez-Aberasturi Beln Maestro-Madurga Amaia Pesquera-Rodríguez Camilo Ramírez-Lpez Leire Lorenzo-Ibarreta Jesús Torrecilla-Soria María C. Villarn-Velasco 《Applied Catalysis A: General》2009,366(2):315-324
The synthesis of glycerol carbonate from glycerol and dimethyl carbonate by transesterification is reported. Firstly, a catalyst screening has been performed by studying the influence of different basic and acid homogeneous and heterogeneous catalysts on reaction results. Catalytic activity is extremely low for acidic catalysts indicating that reaction rate is very slow. On the contrary, high conversions and yields are obtained for basic catalysts. Catalytic activity increases with catalyst basic strength. The best heterogeneous catalyst is CaO. Calcination of CaO increases dramatically its activity due to calcium hydroxide removal from its surface. A reaction optimization study has been carried out with CaO as catalyst by using a factorial design of experiments leading to operation conditions for achieving a 100% conversion and a >95% yield at 1.5 h reaction time: 95 °C, catalyst/glycerol molar ratio = 0.06 and dimethyl carbonate/glycerol molar ratio = 3.5. Carbonate glycerol can be easily isolated by filtering the catalyst out and evaporating the filtrate at vacuum. Leaching of catalyst in reaction medium was lower than 0.34%. Catalyst recycling leads to a quick decrease in both conversions and yields probably due to a combination of catalyst deactivation by CaO exposure to air between catalytic runs, and a decrease in the catalyst surface area available for reaction due to particle agglomeration. 相似文献
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以含有不同取代基的有机锡化合物为催化剂,通过碳酸乙烯酯(EC)与丁二酸二甲酯(DMSu)耦合法制备了聚丁二酸乙二醇酯(PES)和碳酸二甲酯(DMC),并对PES的结构进行了表征。结果表明,有机锡取代基团的电子效应和空间位阻对其催化性能具有很大影响;取代基的吸电子效应越大、空间位阻越小,有机锡的催化活性越高,但若有机锡中存在B酸中心时则容易引起副反应,导致产物选择性差。综合考虑,Bu2SnO的催化性能最好,最优反应条件下,DMC的收率可达到70.08%,PES的特性黏数可达到0.622 dl·g-1。 相似文献
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A process for the production of glycerol carbonate (GC) is proposed with the transesterification of glycerol (GL) and dimethyl carbonate (DMC) with CaO as catalyst by reactive distil ation and extractive distil ation. The perfor-mance of solvents in separating DMC-methanol azeotrope and the effects of operation parameters on the reactive distillation process are investigated experimental y. The results indicate that both the GL conversion and GC yield increase with the DMC/GL molar ratio, reflux ratio, final temperature of tower bottom, and CaO/GL molar ratio and decrease as the recycle number of CaO increases. The calcium concentration in the residual reaction mixture also decreases remarkably as the DMC/GL molar ratio increases. At DMC/GL molar ratio 4.0, reflux ratio 1.0, final temperature of tower bottom 358 K, and CaO/GL molar ratio 0.05, both the GL conversion and GC yield can reach above 99.0%, and the mass concentration of calcium in the product is less than 0.08%. 相似文献
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用绿色化学原料碳酸二甲酯(DMC)代替硫酸二甲酯(DMS)等传统有毒试剂作为甲基化试剂,以间氯苯酚为原料,在固体碱与相转移催化剂(PTC)的作用下,合成了间氯苯甲醚。考察了PTC种类、物料配比、反应时间、反应温度和碱性催化剂用量对反应的影响,通过响应面实验设计,得到最佳反应条件:以四丁基溴化铵(TBAB)为PTC,K2CO3为碱性催化剂,n(间氯苯酚)∶n(DMC)∶n(TBAB)∶n(K2CO3)=1∶3.83∶1.07∶0.5,反应温度为98℃,反应时间为7 h,间氯苯甲醚的得率为98.3%,间氯苯酚的转化率为100%。 相似文献