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1.
砷金矿与锰银矿同时浸出中的超声强化作用   总被引:3,自引:0,他引:3  
在硫酸体系中用两矿法工艺,研究了在超声波强化过程条件下同时浸出含砷金矿和锰银矿,以分解包含金、银的毒砂和氧化锰矿物. 实验表明,在锰银矿/金矿(质量比)=1:1.3、硫酸浓度0.57 mol/L、温度95℃、高频高功率超声波作用条件下,毒砂最终分解率可达84.9%. 而提高毒砂分解率正是提高金浸出率的重要条件.  相似文献   

2.
固定化脂肪酶催化菜籽油合成蜡酯   总被引:2,自引:0,他引:2  
赵晶晶  邓利  谭天伟  王芳 《化工进展》2007,26(9):1311-1315
以菜籽油、鲸蜡醇为原料,采用实验室自制的固定化Candidia sp.99-125脂肪酶分别在有机溶剂和无溶剂体系下合成了蜡酯,在两种体系下对影响蜡酯合成的各种因素进行了比较研究,研究表明:以正己烷为反应介质,在40℃条件下反应12h,油醇摩尔比1∶2,酶量15%(质量分数,上同),水含量7.5%,蜡酯产率可达85.87%;无溶剂体系中在50℃条件下反应20h,油醇摩尔比1∶1.5,蜡酯产率可达80.68%。通过流加鲸蜡醇可以提高酶的使用寿命。  相似文献   

3.
制备了三种用于RTM成型工艺的乙烯基酯树脂,分别命名为R-1,R-2,R-3。系统地研究了三种树脂体系的固化反应特性、工艺特性及其树脂浇铸体的力学性能。研究结果表明,三种树脂体系在室温(25℃)下的粘度都很低,分别为350mPa.s、80mPa.s、70mPa.s,一定温度下的粘度均能达到500mPa.s以下,且具有较长的适用期,符合RTM注射工艺的要求。分析树脂浇铸体的力学性能可以看到,弯曲强度最高可达110.05MPa,冲击强度最高可达12.27kJ/m2。最终选定R-3为综合性能最优的树脂体系。  相似文献   

4.
生物酶法转化酵母油脂合成生物柴油   总被引:4,自引:0,他引:4  
以一株高产油脂圆红冬孢酵母菌(Rhodosporidum toruloides Y4#)干菌粉为原料,利用酸热法提取了该酵母油脂,并对所得油脂进行了分析. 进一步利用该酵母油脂为原料分别研究了无溶剂体系中三步甲醇法及在叔丁醇介质体系中脂肪酶催化合成生物柴油,发现脂肪酶可以有效转化该酵母油脂制备生物柴油. 在优化反应条件下,生物柴油得率可达90%左右,略低于相同条件下利用精制大豆油合成生物柴油的得率.  相似文献   

5.
以钨酸钠为催化剂、过碳酸钠为氧化剂,选择性氧化乙腈制备乙酰胺.研究了该碱性氧化体系的作用,比较了反应时间、温度对反应的影响.考察了钨酸钠的催化性能以及不同碳酸钠用量在体系中的反应结果.反应时间的延长和温度的升高并不利于提高转化率,因此反应选择在室温条件下进行.碳酸钠和氧化体系碱性的增加能促进产物乙酰胺的生成.以钨酸钠为催化剂,反应条件:室温25℃,时间4 h,V[H2O]/V[methnol]=2/3时,乙腈的转化率可达100%左右,生成的乙酰胺的选择性可达94.3%.  相似文献   

6.
张燕  肖光 《当代化工》2009,38(2):103-105
以K2Cr2O7/HCI为反应氧化体系,对以催化裂化柴油进行氧化脱硫实验研究,考察了反应时间、反应温度、氧化剂体积分数、反应体系pH值和萃取剂用量对脱硫效果的影响。实验表明,在最佳反应条件下,柴油的脱硫率可达90%以上。  相似文献   

7.
以K2Cr2O7/HCI为反应氧化体系,对以催化裂化柴油进行氧化脱硫实验研究,考察了反应时间、反应温度、氧化剂体积分数、反应体系pH值和萃取剂用量对脱硫效果的影响。实验表明,在最佳反应条件下,柴油的脱硫率可达90%以上。  相似文献   

8.
采用双硫腙-离子液体[Bmim][PF6](1-丁基-3-甲基咪唑六氟磷酸盐)对水中铅离子的萃取性能及反应条件展开了研究。主要探究了络合剂含量、萃取温度、料液相pH值及萃取体系与水相体积比对萃取效率的影响;此外,在最佳萃取率的前提条件下,进行了反萃剂的筛选,并考察了反萃温度及浓度对反萃效率的影响规律,继而获得最佳反萃条件。研究结果表明,在萃取温度为35 ℃、pH为6、络合剂双硫腙含量为0.5%(w/v)、萃取体系与水相体积比为 1:4 的萃取条件下,该萃取体系对水中铅离子的萃取率高达98.0 %。在35 ℃下,采用1mol/L HNO3对上述负载萃取体系进行反萃,反萃率可达97.0 %。最后,考察了该萃取与反萃体系多次复用的传质效率变化趋势,结果显示三次萃取/反萃后该体系萃取率依然可达80.0 %,反萃率为65.0 %。  相似文献   

9.
王安华 《山东化工》2006,35(6):26-30
对加压法二氧化碳与环氧丙烷合成碳酸丙烯酯催化剂进行了研究,实验结果表明:KI/聚乙二醇400催化体系具有很好的催化活性,可在较低温度、压力下短时间高产率的得到碳酸丙烯酯。碳酸丙烯酯得率可达99.8%以上,在一定条件下。经多次循环使用后仍有较高的活性。  相似文献   

10.
以钨酸钠为催化剂、过碳酸钠为氧化剂,选择性氧化乙腈制备乙酰胺。研究了该碱性氧化体系的作用,比较了反应时间、温度对反应的影响。考察了钨酸钠的催化性能以及不同碳酸钠用量在体系中的反应结果。反应时间的延长和温度的升高并不利于提高转化率,因此反应选择在室温条件下进行。碳酸钠和氧化体系碱性的增加能促进产物乙酰胺的生成。以钨酸钠为催化剂,反应条件:室温25℃,时间4h,V[H2O]/V[methanol]=2/3时,乙腈的转化率可达100%左右,生成的乙酰胺的选择性可达94.3%。  相似文献   

11.
夏咏梅  章克昌 《精细化工》2000,17(5):249-251
以自产铜绿假单胞菌脂肪酶为催化剂 ,通过无溶剂法棕榈油甘油解反应催化合成了单脂肪酸甘油酯。考察了反应温度程序以及加酶方式对最终产物中单甘酯质量分数的影响。结果表明程序降温和批次加酶更有利于反应 ,产物中单甘酯质量分数可增大 1 0 %~ 2 0 % ,实验条件下反应 48h后单甘酯质量分数可达 65 % ,脱酶后达 77%。  相似文献   

12.
A lipase preparation developed from Candida sp. 99‐125 was used for fatty acid alkyl ester synthesis by both enzymatic esterification of fatty acids, and transesterification of oils and fats. The lipase preparation was chosen based on screening of lipases from commercial sources as well as those produced in the laboratory. The effects of enzyme dosage, solvent types, water absorbent additions, inhibition of short‐chain alcohols, alcohol and acid types, molar ratio of substrates, and reusability of the lipase preparation in esterification were studied. Degree of esterification between oleic acid and methanol under optimal conditions reached 92%. Purity of the methyl ester after washing with water and distillation was 98%. Half‐life of the lipase preparation was calculated to be approximately 340 h. For transesterification of rapeseed oil with the same lipase preparation, the amount of methanol and mode of methanol addition to the reaction were also conducted. Transesterification of the oil with stepwise methanol addition reached 83% after 36 h reaction time.  相似文献   

13.
脂肪酶催化合成环十五内脂的酸碱效应   总被引:4,自引:0,他引:4  
以15-羟基十五烷酸甲酯为底物,进行了脂肪酶催化合成环十五内酯研究,考察了酶活性与pH值的关系,探讨了酶粉pH值记忆和有机相酸碱性对内酯化反应的影响。结果表明,pH=6~7时脂肪酶的水解活力最高,pH=6~6.5时15-羟基十五烷酸甲酯转化环十五内酯的转化率最高,添加有机酸碱对内酯化反应产生不利影响。  相似文献   

14.
Lipase from Candida antarctica was entrap-immobilized in cellulose acetate-TiO2 gel fiber (fiber-immobilized lipase) by the sol-gel method. Syntheses of geranyl acetate and citronellyl acetate catalyzed by the fiber-immobilized lipase were studied in heptane solution. Conversions reached 85% for geranyl acetate after 100 h, and 75% for citronellyl acetate after 80 h, and these values were almost identical to those for syntheses catalyzed by nonimmobilized lipase, although the reaction rate was decreased by immobilization. Compared to those of the non-immobilized lipase and commercially available immobilized lipase (Novozyme 435), the activity of the fiber-immobilized lipase was not particularly affected by changes in reaction conditions, such as bulk water content or substrate concentration. The fiber-immobilized lipase retained a high level of activity after six repeated uses, and almost no enzyme leakage from fiber was observed. However, the reactivity of the fiber-immobilized lipase was depressed at higher temperature, presumably due to dehydration by thermal contraction of the gel fiber.  相似文献   

15.
表面活性剂包衣脂肪酶在有机溶剂中催化酯合成   总被引:1,自引:1,他引:0  
用合成的谷氨酸二烷基酯核糖醇对来源于Candidarugosa的脂肪酶进行了包衣 ,以月桂酸与月桂醇的酯化为模型反应 ,研究了各种操作条件对包衣酶活性的影响。结果表明 ,包衣酶制备过程中的缓冲溶液的最适 pH为 6.8,谷氨酸双十二烷基酯核糖醇的包衣效果最好 ,最适反应温度为 3 0℃ ,最佳溶剂为异辛烷。在 10h内底物转化率达 94%。  相似文献   

16.
固定化假丝酵母脂肪酶合成棕榈酸异辛酯   总被引:10,自引:0,他引:10  
陈必强  叶华  谭天伟 《化工学报》2004,55(3):422-425
开发了固定化假丝酵母脂肪酶99-125合成棕榈酸异辛酯的工艺.对反应温度、酶用量、底物摩尔比等酯化反应条件进行了研究.脂肪酶以吸附的形式固定在织物膜上,以1g棕榈酸、0.67g异辛醇、0.12g固定化脂肪酶和5ml石油醚组成的反应系统在40℃条件下反应24h,酯化率可达96.6%.固定化酶连续反应9批后酯化率仍维持在90%以上.  相似文献   

17.
We attempted to produce MAG of CLA through lipase-catalyzed esterification of a FFA mixture containing CLA (referred to as FFA-CLA) with glycerol. Screening of lipases showed that MAG-CLA was produced efficiently at 5°C with Penicillium camembertii, Rhizopus oryzae, and Candida rugosa lipases. Among them, C. rugosa lipase was selected because the lipase is widely used as a catalyst for oils and fats processing. The reaction was conducted with agitation of a 300-g mixture of FFA-CLA/glycerol (1∶5, mol/mol), a 200-U/g mixture of C. rugosa lipase, and 2% water. When the reaction was conducted at 30°C, the esterification scarcely proceeded, owing to inhibition of the reaction by glycerol. But the reaction at 5°C eliminated the inhibition and produced MAG efficiently: The degree of esterification reached 93.8% after 58 h, and MAG content in the reaction mixture was 88.4 wt%. To reduce the reaction time, the reactor was connected with a vacuum pump after 24 h, and the reaction was continued with dehydration at 5 mm Hg. The degree of esterification reached 94.7% after 24 h of dehydration (48 h in total), and MAG content increased to 93.0 wt%. Candida rugosa lipase acted a little more strongly on cis-9, trans-11 CLA than on trans-10,cis-12 CLA, but the contents of the two isomers in MAG obtained from a 48-h reaction were the same as the contents in FFA-CLA.  相似文献   

18.
We attempted to synthesize high-purity structured triacylglycerols (TAG) with caprylic acid (CA) at the 1,3-positions and a polyunsaturated fatty acid (PUFA) at the 2-position by a two-step enzymatic method. The first step was synthesis of TAG of PUFA (TriP), and the second step was acidolysis of TriP with CA. Candida antarctica lipase was effective for the first reaction. When a reaction medium of PUFA/glycerol (3∶1, mol/mol) and 5% immobilized Candida lipase was mixed for 24 h at 40°C and 15 mm Hg, syntheses of TAG of γ-linolenic, arachidonic, eicosapentaenoic, and docosahexaenoic acids reached 89, 89, 88, and 83%, respectively. In these reactions, the lipase could be used for at least 10 cycles without significant loss of activity. In the second step, the resulting trieicosapentaenoin was acidolyzed at 30°C for 48h with 15 mol parts CA using 7% of immobilized Rhizopus delemar lipase. The CA content in the acylglycerol fraction reached 40 mol%. To increase the content further, the acylglycerols were extracted from the reaction mixture with n-hexane and were allowed to react again with CA under conditions similar to those of the first acidolysis. After three successive acidolysis reactions, the CA content reached 66 mol%. The content of dicapryloyl-eicosapentaenoyl-glycerol reached 86 wt% of acylglycerols, and the ratio of 1,3-dicapryloyl-2-eicosapentaenoyl-glycerol to 1(3),2-dicapryloyl-3(1)-eicosapentaenoyl-glycerol was 98∶2 (w/w). In this reaction, the lipase could be used for at least 20 cycles without significant loss of activity. Repeated acidolysis of the other TriP with CA under similar conditions synthesized 1,3-dicapryloyl-2-γ-linolenoyl-glycerol, 1,3-dicapryloyl-2-arachidonoyl-glycerol, and 1,3-dicapryloyl-2-docosahexaenoyl-glycerol in yields of 58, 87, and 19 wt%, respectively.  相似文献   

19.
Wax esters were synthesized in a solvent free system catalyzed by immobilized lipase from Candida sp. 99-125, with oleic acid and cetyl alcohol. The effects of substrate molar ratio, lipase dosage and water removal were investigated in a 50 ml flask incubated in a thermostatic cultivation cabinet. The optimized conditions were: temperature 40 ℃, shaking at 170 r·min-1, acid/alcohol molar ratio 1:0.9, lipase dosage in 10% (by mass) of oleic acid, and open reaction for water removal. As a result, the conversion rate reached 98% for reaction of 8 h. The volume of reactor was scaled up to 1 L three-neck flask. The optimized parameters were: 200 r·min-1 agitation speed, 2.5% (by mass) lipase dosage, others were the same as the parameters described above. The conversion rate reached 95% for reaction of 24 h. The lipase retained 46% conversion rate after reuse for 6, 7 batches. The products were purified by removing remained cetyl alcohol and fatty acids with ethanol and saturated sodium carbonate so-lution, respectively. The purity of the wax ester, cetyl oleate, was 96%. The physical and chemical properties of cetyl oleate were tested and compared with those of jojoba oil. The results show that the product cetyl oleate has great potential to use as the substitute of natural jojoba oil.  相似文献   

20.
无溶剂体系中酶催化合成共轭亚油酸甘油酯   总被引:1,自引:0,他引:1  
采用直接酯化法,以共轭亚油酸(简称CLA)和甘油为原料,用脂肪酶Novozym 435催化合成共轭亚油酸甘油酯。结果表明:n(甘油)/n(CLA)=5,酶添加量为体系总质量的4%,65℃反应6 h后,共轭亚油酸的转化率为98.18%。所得共轭亚油酸甘油酯为淡黄色油状透明液体,酸价低于3,Novozym 435的操作半衰期为30 h。  相似文献   

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