过饱和铝酸钠溶液结构性质与分解机理研究现状*

过饱和铝酸钠溶液分解是氧化铝生产过机理的研究是氧化铝生产过程的重要基础问题.本文对过饱和铝酸钠溶液中铝酸根离子存在的基本形态,浓度、苛性比和阳离子对铝酸钠溶液结构性质的影响,溶液中多种铝酸根离子平衡与转化规律,以及铝酸钠溶液分解机理研究的现状进行了总结和评述;分析了现有铝酸钠溶液结构性质与分解机理研究的不足;围绕强化氧化铝生产中铝酸钠溶液分解过程的目的,提出了铝酸钠溶液结构性质与分解机理研究的重点.     

利用甲醇尾气中二甲醚制取二甲基硫醚

采用二甲醚和二硫化碳为原料的方法生产了二甲基亚砜的中间产品二甲基硫醚.甲醇是有机合成工业的基本原料,在国防、医药、农药等方面被广泛应用.在精制年醇过程中,产生大量的二甲醚有毒气体,为了搞好综合利用和保护环境而回收利用这些气体,是一项有意义的工作. 我厂拟用放空尾气中的二甲醚生产二甲基亚矾.生产     

结合实用技术进行课堂教学

在教学过程中,根据中学化学内容,有机地结合当地工农业生产和日常生活介绍一些实用技术,有助于激发学生的学习兴趣,促进教学质量的提高.使学生在学习中感受到知识就是力量,体会到掌握中学化学基础知识是适应生产和现代化生活的需要.两年多来,我们从以下方面做了一些尝试.     

鸡蛋壳制备葡萄糖酸钙的研究

葡萄糖酸钙是一种溶解度高,生理宽容性大的钙营养剂和抗过敏药,广泛用作食品添加剂及医药制剂供口服或静脉注射.目前常用的生产方法主要是生物发酵法,其缺点是工艺复杂, 生产周期长且易造成污染.本研究以葡萄糖酸δ内酯作为葡萄糖酸的来源,利用蛋壳中所含高达93%的CaCO3[1]进行中和反应制备葡萄糖酸钙,探索了一条变废为宝,工艺简单,成本低,污染小的葡萄糖酸钙生产路线.     

玻璃成分分析标准物质的研究及应用

玻璃标准物质是用于比较的基准物质,在玻璃的生产和质量控制中是保证数值有效可靠的基础.分析了国内外玻璃标准物质的研究进展情况,论述了玻璃标准物质的作用,同时指出了现阶段玻璃标准物质研究中存在的问题,并指出了其未来的发展方向.     

铜基催化剂LP201在合成气一步法制备二甲醚三相过程中的应用

 目前二甲醚作为一种重要的能源受到广泛关注. 实现生产二甲醚工艺的重点是采用一种廉价的生产流程及研制出性能优异的催化剂. 本文采用普遍好评的三相反应器中合成气一步生产二甲醚的新工艺,并开发出具有优异催化性能的铜基催化剂LP201. 对该催化剂的活性及热稳定性进行了评价,并利用多种手段对催化剂进行了表征,从机理上阐述了该催化剂的优越性.     

ITO废靶中铟的回收

从ITO废靶中回收铟是生产中亟待解决的问题.通过试验,提出了盐酸浸出,中和除锡,铟置换,锌置换铟,压团和熔铸得到粗铟,然后电解精炼得到纯度99.99%铟的工艺.     

冶金过程中熔渣发泡现象的定量描述

本文分析了冶金过程中不同发泡现象的特点,以及引起不同发泡现象的气体来源.确定了描述不同气体来源引起发泡现象的发泡特性参数.讨论了用发泡特性参数来定量描述冶金生产中不同发泡过程的方法和给出熔渣发泡高度与熔渣物性参数和操作参数的关系,为在生产中实际应用提供必要的基础.     

分析测试新方法(204~209)裂解气相色谱-质谱法测定氨纶废丝中油剂的含量

氨纶是一种聚氨酯弹性纤维,应用领域广阔. 在对氨纶生产过程中产生的大量废丝进行回收重复利用时,所添加的油剂会对甬道发生堵塞,因此在氨纶废丝回收之前需要对其进行清洗来控制油剂的含量. 运用裂解气相色谱-质谱法(PY-GC/MS)建立了1种测试氨纶废丝中油剂残余含量的方法. 方法简单快捷,无需任何样品前处理,为氨纶废丝的清洗工作,尤其是工业化清洗生产提供了准确可靠的数据.     

裂解气相色谱-质谱法测定氨纶废丝中油剂的含量

氨纶是一种聚氨酯弹性纤维,应用领域广阔.在对氨纶生产过程中产生的大量废丝进行回收重复利用时,所添加的油剂会对甬道发生堵塞,因此在氨纶废丝回收之前需要对其进行清洗来控制油剂的含量.运用裂解气相色谱-质谱法(PY-GC/MS)建立了1种测试氨纶废丝中油剂残余含量的方法.方法简单快捷,无需任何样品前处理,为氨纶废丝的清洗工作,尤其是工业化清洗生产提供了准确可靠的数据.     

Application of a Chitosan-Immobilized Talaromyces thermophilus Lipase to a Batch Biodiesel Production from Waste Frying Oils

Waste frying oil, which not only harms people’s health but also causes environmental pollution, can be a good alternative to partially substitute petroleum diesel through transesterification reaction. This oil contained 8.8 % of free fatty acids, which cause a problem in a base-catalyzed process. In this study, synthesis of biodiesel was efficiently catalyzed by the covalently immobilized Talaromyces thermophilus lipase and allowed bioconversion yield up to 92 % after 24 h of reaction time. The optimal molar ratio was four to six parts of methanol to one part of oil with a biocatalyst loaded of 25 wt.% of oil. Further, experiments revealed that T. thermophilus lipase, immobilized by a multipoint covalent liaison onto activated chitosan via a short spacer (glutaraldehyde), was sufficiently tolerant to methanol. In fact, using the stepwise addition of methanol, no significant difference was observed from the one-step whole addition at the start of reaction. The batch biodiesel synthesis was performed in a fixed bed reactor with a lipase loaded of 10 g. The bioconversion yield of 98 % was attained after a 5-h reaction time. The bioreactor was operated successfully for almost 150 h without any changes in the initial conversion yield. Most of the chemical and physical properties of the produced biodiesel meet the European and USA standard specifications of biodiesel fuels.     

柴油溶剂中脂肪酶催化高酸值废油脂酯化制备生物柴油

采用0＃柴油作为反应溶剂,利用固定化脂肪酶催化高酸值废油脂与甲醇酯化反应制备生物柴油。来源于Candida antarctica的固定化脂肪酶Novozym435在0＃柴油溶剂中具有极高的催化活性。以酸价高达157×10-3的废油脂为原料,废油脂质量比10%的Novozym435,甲醇与废油脂初始摩尔比2∶1,0＃柴油与废油脂质量比5∶1,摇床摇速170r/min,50℃下反应2h甲酯化率可达95.10%。0＃柴油作为反应溶剂有效地溶解了高酸值废油脂和甲醇,降低了反应体系的黏度和消除了甲醇对Novozym435的负面影响,提高了Novozym435的稳定性。同时,0＃柴油溶剂对未脱胶废油脂中残留的对脂肪酶有害的磷脂等胶类物质具有一定的稀释作用。该工艺省却了溶剂蒸馏的繁琐工序,直接得到脂肪酸甲酯和石化柴油的混合燃料。     

基于氯化镁饱和溶液中固定化脂肪酶Lipozyme TL IM催化光皮树油脂合成生物柴油

基于氯化镁饱和溶液反应体系中,对采用固定化脂肪酶Lipozyme TL IM催化光皮树油脂转化为生物柴油的工艺进行了研究。考察了固定化脂肪酶Lipozyme TL IM催化光皮树油转酯化的工艺中甲醇的用量、固定化脂肪酶的添加量、摇床的转速和反应时间对生物柴油产率的影响。实验结果表明,采用氯化镁饱和溶液反应体系,在醇油摩尔比为3∶1,固定化酶Lipozyme TL IM用量为光皮树油质量的20%,摇床转速为150 r/min,反应8 h时,生物柴油产率最高,达到86.5%。与传统的三步甲醇醇解或者有机溶剂反应体系比较,采用的氯化镁饱和溶液体系的酶稳定性更好,反应效率更高,有效地解决了酶在甲醇中失活的问题,生产成本低,可成为生产生物柴油的新工艺。     

华根霉全细胞脂肪酶催化合成生物柴油

比较了5种不同商品化脂肪酶和自制的华根霉CCTCCM201021全细胞脂肪酶(RCL)催化油脂合成生物柴油的转化效果,结果表明,RCL能有效应用于无溶剂体系催化合成生物柴油.在无溶剂体系中对该酶催化生物柴油的转酯化反应工艺进行优化,考察了甲醇用量、体系含水量、酶的添加量和反应温度对生物柴油收率的影响,使生物柴油最终收率大于86.0%.在有机溶剂体系中选择不同有机溶剂作为助溶剂进行转酯化反应,发现logP值在4.0～4.5的有机溶剂具有较好的转化效果.其中以正庚烷为助溶剂的转酯化反应具有最高的生物柴油收率86.7%.在无溶剂体系中RCL催化转化油酸和模拟高酸价油脂合成脂肪酸甲酯的研究表明,该酶具有很好的催化合成生物柴油的潜力.     

Production of biodiesel by immobilized Candida sp. lipase at high water content

A new process for enzymatic synthesis of biodiesel at high water content (10–20%) with 96% conversion by lipase from Candida sp. 99–125 was studied. The lipase, a no-position-specific lipase, was immobilized by a cheap cotton membrane and the membrane-immobilized lipase could be used at least six times with high conversion. The immobilized lipase could be used for different oil conversion and preferred unsaturated fatty acids such as oleic acid to staturated fatty acids such as palmitic acid. The changes in concentration of fatty acids, diglycerides, and methyl esters in the reaction were studied and a mechanism of synthesis of biodiesel was suggested: the triglycerides are first enzymatically hydrolyzed into fatty acids, and then these fatty acids are further converted into methyl esters.     

Biodiesel Production from Various Oils Under Supercritical Fluid Conditions by Candida antartica Lipase B Using a Stepwise Reaction Method

In this study, we evaluate the effects of various reaction factors, including pressure, temperature, agitation speed, enzyme concentration, and water content to increase biodiesel production. In addition, biodiesel was produced from various oils to establish the optimal enzymatic process of biodiesel production. Optimal conditions were determined to be as follows: pressure 130 bar, temperature 45 °C, agitation speed 200 rpm, enzyme concentration 20%, and water contents 10%. Among the various oils used for production, olive oil showed the highest yield (65.18%) upon transesterification. However, when biodiesel was produced using a batch system, biodiesel conversion yield was not increased over 65%; therefore, a stepwise reaction was conducted to increase biodiesel production. When a reaction medium with an initial concentration of methanol of 60 mmol was used and adjusted to maintain this concentration of methanol every 1.5 h during biodiesel production, the conversion yield of biodiesel was 98.92% at 6 h. Finally, reusability was evaluated using immobilized lipase to determine if this method was applicable for industrial biodiesel production. When biodiesel was produced repeatedly, the conversion rate was maintained at over 85% after eight reuses.     

A kinetic study on lipase-catalyzed interesterification of soybean oil with oleic acid in a continuous packed-bed reactor

To provide a mathematical basis for the design and operation of a continuous, packed-bed reactor for the interesterification of soybean oil, soybean oil that contains 22.7% oleoyl and 54.3% linoleoyl moieties as molar acyl moiety composition was interesterified in hexane with oleic acid, using an immobilized sn-1,3-specific lipase (Lipozyme IM) from Mucor miehei. The reaction was carried out in a U-shaped Pyrex glass-made packed-bed reactor at 37°C in the following system: concentration of soybean oil in the feed stream=12.5 wt%, molar ratio of fatty acid to soybean oil=3.0, and water content in the feed stream=1340–2340 ppm. At these water contents, Lipozyme IM gave practically the same catalytic activity, and the content of triacylglycerols in the product oil was 91–94 wt%. Rate equations for the change in oleoyl and linoleoyl moiety compositions in soybean oil were derived and their validity was confirmed experimentally. On the other hand, the catalytic activity of Lipozyme IM decayed in the first-order fashion. Based on these deactivation kinetics, the flow rate of the feed stream is simulated for the operation of a continuous, packed-bed reactor at 37°C that produces an oil of a fixed composition of oleoyl moiety.     

Synthesis of SBA-15 from low cost silica precursor obtained from sugarcane leaf ash and its application as a support matrix for lipase in biodiesel production

Ordered mesoporous silica material was synthesized from a low-cost precursor, sugarcane leaf ash, was used as a support matrix for lipase for the production of biodiesel. The mesoporous samples were characterized using Fourier transform infra red spectroscopy. The surface topography and morphology of the mesoporous materials were studied using scanning electron microscope. The pore diameter, pore volume, Brunauer Emmett and Teller surface area of the mesoporous material were determined by N₂ gas adsorption technique. Different pore size Santa Barbara Acid-15 (SBA-15) samples were synthesized and their lipase immobilization capacity and specific enzyme activity of immobilization lipase were determined and compared. Lipase from Candida Antarctica immobilized on SBA-15 (C) had shown maximum percentage immobilization and specific enzyme activity. The immobilized lipase mesoporous matrix was used for biodiesel production from crude non-edible Calophyllum inophyllum oil. The percentage yield of fatty acid methyl ester, 97.6 % was obtained under optimized conditions: 100 mg of lipase immobilized on SBA-15, 6:1 methanol to oil molar ratio, the reaction of 2 g C. inophyllum oil with methanol.     

Optimization of lipase-catalyzed transesterification of lard for biodiesel production using response surface methodology

Biodiesel, an alternative diesel fuel made from renewable biological resources, has become more and more attractive recently. Combined use of two immobilized lipases with complementary position specificity instead of one lipase is a potential way to significantly reduce cost of lipase-catalyzed biodiesel production. In this study, the process of biodiesel production from lard catalyzed by the combined use of Novozym435 (non-specific) and Lipozyme TLIM (1,3-specific) was optimized by response surface methodology. The optimal reaction conditions were 0.04 of amount of lipase/oil (w/w), 0.49 of proportion of Novozym435/total lipases (w/w), 0.55 of quantity of tert-butanol/oil (v/v), 5.12 of quantity of methanol/oil (mol/mol), and 20 h of reaction time, by which 97.2% of methyl ester (ME) yield was attained, very close to the predicted value (97.6%). This optimal reaction condition could be true of other similar reactions with plant and animal oil resources; their ME yield could be higher than 95%. The lipases regenerated by washing with organic solvent after each reaction cycle could be continuously reused for 20 cycles without any loss of activity, exhibiting very high manipulation stability.     

Enzymatic conversion of waste cooking oils into alternative fuel—Biodiesel

Production of biodiesel from pure oils through chemical conversion may not be applicable to waste oils/fats. Therefore, enzymatic conversion using immobilized lipase based on Rhizopus orzyae is considered in this article. This article studies this technological process, focusing on optimization of several process parameters, including the molar ratio of methanol to waste oils, biocatalyst load, and adding method, reaction temperature, and water content. The results indicate that methanol/oils ratio of 4, immobilized lipase/oils of 30 wt% and 40°C are suitable for waste oils under 1 atm. The irreversible inactivation of the lipase is presumed, and a stepwise addition of methanol to reduce inactivation of immobilized lipases is proposed. Under the optimum conditions the yield of methyl esters is around 88–90%.