棉籽油甲酯化联产生物柴油和甘油

介绍了在KOH催化剂作用下棉籽油与甲醇反应生成棉籽油甲酯即生物柴油的研究工作。用精棉籽油和毛棉籽油为原料，考察酯交换反应条件如醇油比、催化剂用量、反应温度、反应时间对棉籽油转化率和甲酯得率的影响。应用正交实验的方法得出精棉籽油酯交换反应的最佳反应条件为：反应温度45℃，醇油摩尔比为6：1，催化剂用量为1．1％，反应时间为60min。采用常压蒸馏的方法回收酯交换反应中过剩的甲醇。同时研究了甘油分离精制的方法，所得甘油的纯度可达97．86％。实验室制得的棉籽油甲酯生物柴油的主要性能指标符合ASTM制定的生物柴油的标准。     

固体酸催化蓖麻油制备生物柴油

以一水硫酸氢钠固体酸为催化剂,对蓖麻油酯交换制备生物柴油进行了研究。在反应温度为75℃条件下,考察了醇油摩尔比、催化剂用量(占油质量)及反应时间对酯交换反应的影响。在反应温度为75℃、醇油摩尔比为9∶1、催化剂用量为4%、反应时间为8 h的优化工艺条件下,平均甘油收率达93%,产物中甲酯总含量为95.20%。甲酯和甘油静置分层快,后处理简单,对环境无污染。     

微波-固体酸催化棉籽油制备生物柴油的研究

探讨了微波辅助条件下采用新型固体酸S2082-/Al2O3-ZrO2-La2O3替代传统的液体酸、碱催化剂,催化棉籽油与甲醇进行酯交换反应制备生物柴油。考察了微波功率、固体酸催化剂用量、醇油摩尔比、反应温度等因素对产物中甲酯含量的影响。结果表明,在微波辅助下,固体酸催化剂对棉籽油酯交换具有较好的催化活性和稳定性,产物与催化剂易于分离。在微波功率300W,反应温度120℃,醇油摩尔比12：1,固体酸催化剂用量为油质量的3%条件下,反应1.5h产物中棉籽油甲酯含量达到95.2%,催化剂重复使用10次甲酯含量维持在90%左右,表明催化剂具有较高的催化活性和稳定性。     

L-抗坏血酸硬脂酸酯--新型营养抗氧化剂的合成研究

考察了以硬脂酸甲酯和L-抗坏血酸为原料,通过酯交换法合成L-抗坏血酸硬脂酸酯的工艺,并通过正交实验对其反应条件进行优化设计.研究结果表明,最佳反应条件为:抗坏血酸:硬脂酸甲酯为1:1.3(摩尔比),催化剂浓硫酸:(抗坏血酸 甲酯)为1:0.10(摩尔比),反应温度24℃,反应时间24 h.在此条件下可获得总产率为77%,熔点为106～114℃的白色粉末状的抗坏血酸硬脂酸酯.     

邻苯二甲酰亚胺钾催化合成生物柴油北大核心CSCD

针对酯交换法合成生物柴油中均相催化剂不容易分离和非均相催化剂易失活和用量大等问题,提出用邻苯二甲酰亚胺钾催化大豆油和甲醇合成生物柴油。通过单因素实验考察了催化剂邻苯二甲酰亚胺钾用量、醇油摩尔比、反应温度和反应时间对甘油三酯转化率的影响,并利用Design-Expert软件通过响应面实验对合成反应条件进行了优化。考察了邻苯二甲酰亚胺钾在甘油和甲醇中的溶解度和作为催化剂的重复使用性能。通过红外光谱和气相色谱-质谱对生物柴油的结构和组成进行了分析。结果表明:合成生物柴油的最佳反应条件为反应温度60℃、醇油摩尔比7.15∶1、反应时间2.4 h、催化剂用量1.2%,在此条件下甘油三酯转化率为96.0%;催化剂在高温下溶于甲醇和甘油,在低温下可在甘油中析出;催化剂循环使用4次,甘油三酯转化率仍在85%以上;红外光谱和气相色谱-质谱分析表明,生物柴油被成功合成,棕榈酸甲酯、油酸甲酯、亚油酸甲酯和硬脂酸甲酯含量为83.09%。综上,邻苯二甲酰亚胺钾作为合成生物柴油的催化剂,具有较高的催化性能和较好的重复使用性,可以实现均相酯交换反应和非均相分离。     

响应面法优化甘油酯转甲酯化条件

在反应温度、反应时间和甲醇钠用量3个单因素实验基础上,利用响应面分析法,以交酯化后样品中甘油和VE含量为评价指标,对甘油酯转甲酯化最佳条件进行了研究。结果表明,最佳反应温度73.7℃、反应时间2.1 h、甲醇钠用量0.51%(W/W)。在最佳条件下,VE保存率为90.5%,酯化率为89.4%。     

废弃油脂甘油酯化降酸过程中的甘油聚合研究

基于甘油酯化降酸的优势和降酸过程甘油聚合的问题,开展了废弃油脂甘油酯化降酸过程中甘油聚合的研究。考察了反应温度、甘油用量、催化剂种类、催化剂用量对甘油聚合的影响,并分析了聚甘油的聚合度。结果表明:反应温度越高、甘油与脂肪酸摩尔比越大,降酸速率越快,甘油聚合率越高,在反应温度220℃、甘油与脂肪酸摩尔比1∶1时甘油聚合率约为33.8%;聚甘油主要为二聚甘油;甘油酯化过程引入锌基催化剂,不仅提高降酸速率,缩短反应时间,还能降低反应温度、减少甘油的聚合,从而提高副产物甘油的回收率;与催化剂Zn Cl_2、Zn(Ac)_2相比,催化剂Zn O效果最好,在Zn O用量0.3%、反应温度180℃、甘油与脂肪酸摩尔比1∶1时甘油聚合率可降至约13%。研究结果将有助于进一步优化甘油酯化降酸工艺,为甘油酯化耦合碱催化酯交换法制备生物柴油技术的设计提供参考。     

响应面法优化超声波辅助猪油酯交换反应制备生物柴油的研究

以猪油和甲醇为原料,KOH为催化剂,采用单因素法确定醇油摩尔比、超声波功率、催化剂用量、反应温度等因素对猪油酯交换反应的脂肪酸甲酯产率的影响。单因素实验结果显示各因素的最佳值分别为醇油摩尔比6∶1,超声波功率为120 W,催化剂用量为0.8%,反应温度为60℃。采用响应面分析法优化超声强化KOH均相碱催化酯交换条件,结果显示最优条件为:醇油摩尔比为5.8∶1,超声功率为135.91W,反应温度为52.78℃,催化剂用量为0.86%,在该条件下甲酯最大的理论转化率为99.53%。     

超声波——固体碱催化黄连木籽油制备生物柴油

在超声波辅助条件下采用新型固体碱Li_2O/MgO替代传统液体酸、碱催化剂,催化黄连木籽油与甲醇进行酯交换反应制备生物柴油;考察超声波功率、超声波频率、固体碱催化剂用量、反应温度、醇油摩尔比等因素对产物中甲酯含量影响。结果表明,在超声波辅助下,固体碱催化剂对黄连木籽油酯交换具有较好催化活性和稳定性,在超声波功率70 W、超声波频率28 Hz、固体碱催化剂用量为油质量1.5%、反应温度60℃、醇油摩尔比9:1条件下,反应2 h产物中甲酯含量达98.6%;催化剂重复使用十次,甲酯含量维持在92%左右,表明催化剂具有较高催化活性和稳定性;且制备生物柴油质量达到国家柴油机燃料调合用生物柴油(BD100)标准。     

生物柴油副产物甘油精制工艺研究

以棕榈油为原料,碱法催化甲醇与棕榈油进行酯交换反应生成脂肪酸甲酯(即生物柴油)和副产物甘油。副产物粗甘油经过磷酸中和得到甘油半成品,再经过乙醇结晶、分子蒸馏得到高纯度甘油产品。通过正交实验得到乙醇结晶的最佳条件为:结晶温度20℃,结晶时间20 min,乙醇添加量为1∶1(V/W)。乙醇结晶后的甘油在温度110℃,压力30 Pa下进行分子蒸馏,得到纯度为99.5%的高纯度甘油。     

甘油发酵工艺的初步研究

以一种耐高渗透压的酵母为生产菌株,探讨了甘油发酵工艺对生产甘油的影响。结果表明:过低和过高的通气量都不利于甘油的生产,采用90L/h的通气量可获得较高的甘油得率;发酵液中pH的变化对甘油的生产影响显著,通过补加硫铵和自动调控pH,发酵时间大大缩短,甘油得率明显提高,达到了41.5％。     

基于聚吡咯/石墨烯的甘油酶电极的构建及性能研究

本文以循环伏安法在玻碳电极表面制备了聚吡咯(PPy)膜,以水热还原法制备了三维石墨烯(GN),并以此构建了甘油酶电极。所构建的甘油酶电极以甘油激酶(GK)和甘油三磷酸氧化酶(GPO)为催化剂,以三维石墨烯(GN)为载体,以聚吡咯(PPy)为介体,以Nafion溶液作为粘结剂。该甘油酶电极可以在酶、介体及电极表面提供良好的电子转移。论文探究了吡咯的聚合条件,并采用扫描电子显微镜及电化学方法对其进行了表征;对该酶电极的修饰材料、工作条件等进行了优化,采用电化学方法对其性能进行了评价。结果表明,聚吡咯的聚合圈数为8时其导电性能最优,所述的基于聚吡咯/石墨烯的甘油酶电极在pH为7.0,浓度为0.2mmol/L的磷酸缓冲溶液对甘油有着较高的电流响应,其催化电流达46.2μA,电流密度达677.6μA/cm~2。     

GUT2, a gene for mitochondrial glycerol 3-phosphate dehydrogenase of Saccharomyces cerevisiae

A gut2 mutant of Saccharomyces cerevisiae is deficient in the mitochondrial glycerol 3-phosphate dehydrogenase and hence cannot utilize glycerol. Upon transformation of a gut2 mutant strain with a low-copy yeast genomic library, hybrid plasmids were isolated which complemented the gut2 mutation. The nucleotide sequence of a 3·2 kb PstI-XhoI fragment complementing a gut2 mutant strain is presented. The fragment reveals an open reading frame (ORF) encoding a polypeptide with a predicted molecular weight of 68·8 kDa. Disruption of the ORF leads to a glycerol non-utilizing phenotype. A putative flavin-binding domain, located at the amino terminus, was identified by comparison with the amino acid sequences of other flavoproteins. The cloned gene has been mapped both physically and genetically to the left arm of chromosome IX, where the original gut2 mutation also maps. We conclude that the presented ORF is the GUT2 gene and propose that it is the structural gene for the mitochondrial glycerol 3-phosphate dehydrogenase.     

Overexpression of the genes of glycerol catabolism and glycerol facilitator improves glycerol conversion to ethanol in the methylotrophic thermotolerant yeast Ogataea polymorpha

Production of fuel ethanol is one of the possible ways to utilize crude glycerol, substantial amounts of which are produced by biodiesel industry. Earlier, we have described construction of the recombinant strains of methylotrophic thermotolerant yeast Ogataea polymorpha with simultaneous overexpression of the genes PDC1 and ADH1, which produced increased amounts of ethanol from glycerol. In this work, we have further improved these strains by overexpression of genes involved either in oxidative (through dihydroxyacetone) or phosphorylative (through glycerol-3-phosphate) pathway of glycerol catabolism, as well as heterologous gene coding for glycerol transporter FPS1 from Komagataella phaffii (formerly, Pichia pastoris). Obtained recombinant strains produced up to 10.7 g/L of ethanol (with ethanol productivity 30 mg/g of biomass/hr and yield 132 mg/g of consumed glycerol) from pure glycerol and up to 3.55 g/L of ethanol (with ethanol productivity 11.6 mg/g of biomass/hr and yield 72.3 mg/g of consumed glycerol) from crude glycerol as a carbon source, which is approximately 15 times more relative to that of the O. polymorpha wild-type strain and 2.2 more relative to the earlier constructed strain.     

克雷伯杆菌生产1,3-丙二醇关键酶酶活分析方法研究

有氧条件下,建立了克雷伯杆菌破碎方法及其生产1,3-丙二醇代谢途径中关键酶酶活测定方法。超声波细胞破碎优化条件为:超声频率30kHz,100%振幅,间歇频率0.6,超声时间12min。细胞抽提液中甘油脱氢酶、1,3-丙二醇氧化还原酶、甘油脱水酶酶活测定的最适pH分别为12、9.5和7.0,最适温度分别为45oC、45oC和37。甘油脱氢酶、1,3-丙二醇氧化还原酶用初速度法测定。甘油脱水酶用终止法测定。     

Li掺杂CeO2固体碱催化甘油酯交换合成碳酸甘油酯

针对由甘油制备碳酸甘油酯的酯交换法中催化剂制备方法复杂、活性组分易流失等问题,采用一锅法制备了Li掺杂CeO₂固体碱催化剂。对催化剂进行了X射线衍射(XRD)、扫描电镜(SEM)、透射电镜(TEM)、BET、X射线光电子能谱(XPS)、CO₂程序升温脱附(CO₂-TPD)等表征。以甘油转化率和碳酸甘油酯产率为指标,对催化剂进行了筛选,并采用单因素实验对甘油酯交换合成碳酸甘油酯的工艺条件进行了优化,同时考察了催化剂的重复使用性能。结果表明：Li与CeO₂之间能够产生协同作用,Li的掺杂能够明显增加CeO₂的中强碱活性位点;Li、Ce与柠檬酸物质的量比为0.3∶1∶1时,催化剂催化活性最好;甘油酯交换合成碳酸甘油酯的最优反应条件为反应温度100℃、反应时间2.0 h、催化剂用量为甘油质量的1%、甘油与碳酸二甲酯物质的量比1∶2,在此条件下甘油转化率为90.16%,碳酸甘油酯收率为90.04%;催化剂在重复使用5次后活性无明显下降。采用一锅法制备的Li掺杂CeO₂     

Feeding value of glycerol as a replacement for corn grain in rations fed to lactating dairy cows

Growth of the corn ethanol industry has created a need for alternatives to corn for lactating dairy cows. Concurrent expansion in soydiesel production is expected to increase availability and promote favorable pricing for glycerol, a primary co-product material. The objective of this study was to determine the feeding value of glycerol as a replacement for corn in diets fed to lactating dairy cattle. Sixty lactating Holstein cows housed in individual tie stalls were fed a base diet consisting of corn silage, legume forages, corn grain, soyhulls, roasted soybeans, and protein supplements. After a 2-wk acclimation period, cows were fed diets containing 0, 5, 10, or 15% refined glycerol for 56 d. Cows were milked twice daily and weekly milk samples were collected. Milk production was 36.3, 37.2, 37.9, and 36.2 ± 1.6 kg/d and feed intake was 23.8, 24.6, 24.8, and 24.0 ± 0.7 kg/d for 0, 5, 10, and 15% glycerol treatments, respectively, and did not differ except for a modest reduction in feed intake during the first 7 d of the trial for 15% glycerol (treatment × time effect). Milk composition was not altered by glycerol feeding except that milk urea nitrogen was decreased from 12.5 ± 0.4 to 10.2 ± 0.4 mg/dL with glycerol addition. Cows fed diets containing 10 and 15% glycerol gained more weight than those fed rations containing 0 or 5% glycerol but body condition scores did not differ with glycerol feeding. The data indicate that glycerol is a suitable replacement for corn grain in diets for lactating dairy cattle and that it may be included in rations to a level of at least 15% of dry matter without adverse effects on milk production or milk composition.     

生物柴油生产及其副产物甘油的有效利用

甘油是生产生物柴油的主要副产品,随着世界范围内生物柴油需求量和生产量的迅猛增长,甘油的有效利用也成为紧迫课题。对生物柴油的生产及利用,生物柴油副产物甘油生产高附加值的新产品和新途径进行了介绍,以期充分利用天然再生资源。     

Chronic metabolic responses of postpartal dairy cows to subcutaneous glucagon injections, oral glycerol, or both

We examined the long-term effects of daily subcutaneous injections of 15 mg of glucagon during the first 14 d postpartum with or without coadministration of 400 mL of pure glycerol orally on blood metabolites and hormones and liver composition of Holstein dairy cows during early lactation. Fourteen multiparous cows with body condition score of ≥3.5 points (1-5 point scale) were assigned randomly to one of 4 treatment groups—saline, glucagon, glycerol, or glucagon plus glycerol. Fatty liver syndrome was induced by feeding cows a dry-cow ration supplemented with 6 kg of cracked corn daily during the last 6 wk of the dry period. Compared with saline treatment (n = 3), coadministration of glucagon and glycerol (n = 4) increased plasma glucose and insulin and decreased plasma nonesterified fatty acid concentrations in both treatment weeks, whereas glucagon alone (n = 3) produced similar changes plus a decrease in plasma β-hydroxybutyrate in the second week only. No significant changes were observed for the glycerol alone treatment (n = 4). We conclude that a single daily dose of glycerol for the first 14 d postpartum may potentiate the action of glucagon in the first treatment days to alleviate some symptoms of fatty liver syndrome, such as the increase in plasma nonesterified fatty acids and the decrease in plasma glucose and insulin, in Holstein dairy cows after parturition.