微量酸催化麻疯树籽油制备生物柴油(英文)

Biodiesel produced from crude Jatropha curcas L.oil with trace sulfuric acid catalyst(0.02%-0.08% oil) was investigated at 135-184 ℃.Both esterification and transesterification can be well carried out simultane-ously.Factors affecting the process were investigated,which included the reaction temperature,reaction time,the molar ratio of alcohol to oil,catalyst amount,water content,free fatty acid(FFA) and fatty acid methyl ester(FAME) content.Under the conditions at 165 ℃,0.06%(by mass) H2SO4 of the oil mass,1.6 MPa and 20:1 methanol/oil ratio,the yield of glycerol reached 84.8% in 2 hours.FFA and FAME showed positive effect on the transesterification in certain extent.The water mass content below 1.0% did not show a noticeable effect on trans-esterification.Reaction kinetics in the range of 155 ℃ to 175 ℃ was also measured.     

Hydrolysis of mechanically pre-treated cellulose catalyzed by solid acid SO_4~(2-)-TiO_2 in water–ethanol solvent

An efficient catalyst SO_4~(2-)-TiO_2(ST) from industrial metatitanic acid has been successfully prepared to catalyze hydrolysis of ball-milling cellulose. The results show that the highest catalytic efficiency is obtained for ST calcined at 450 °C(ST-450) with the yield of 21.8% glucose, 13.0% 5-HMF and 4.2% furfural at 200 °C for30 min. The ball milling of cellulose and solid acid catalyst significantly enhances the cellulose hydrolysis. The high Lewis to Br?nsted acid sites ratio for ST-450 induced by bidentate ligands between SO_4~(2-)and TiO_2 benefits high organics yield, and high total acid sites contribute to the high cellulose conversion. The large pore volume of0.29 cm~3·g~(-1) and appropriate pore size of 7.35 nm of ST-450 also contribute to the high performance. High reaction temperature over 200 °C exhibits negative effect on glucose and 5-HMF yield due to undesired side reactions, while furfural product is stable in the reaction system. The bidentate ligands between SO_4~(2-)and TiO_2 are considered as active acid sites for cellulose hydrolysis in water–ethanol solvents.     

小麦秸秆制备乙酰丙酸的动力学研究

Levulinic acid is considered as a promising green platform chemical derived from biomass. The kinetics of levulinic acid accumulation in the hydrolysis process of wheat straw was investigated in the study. Using dilute sulfuric acid as a catalyst, the ki-netic experiments were performed in a temperature range of 190-230C and an acid concentration range of 1%-5% (by mass). A simple model of first-order series reactions was developed, which provided a satisfactory interpretation of the experimental results. The kinetics of main intermediates including sugar and 5-hydroxymethylfurfural (5-HMF) were also established. The kinetic pa-rameters provided useful information for understanding the hydrolysis process.     

Microwave-assisted leaching of vanadium from vanadium slag with sulfuric acid

Microwave irradiation was used to investigate vanadium slag in place of traditional heating.Factors associated with vanadium extraction ratio were studied following the concentration of leaching agent,oxidant dosage,microwave power,microwave irradiation time and mass ratio of liquid to solid.Results indicated that leaching ratio based on microwave leaching at atmospheric pressure can get to 68.48% under the conditions following sulfuric acid concentration 30%,mass ratio of liquid to solid ratio 2∶1,mass ratio of vanadium slag to manganese dioxide dosage 25∶1.4,and microwave power 800W for 3.5 h at 95 ℃.While,leaching ratio based on microwave leaching under pressure was up to 45.79% under the conditions following sulfuric acid concentration 20%,mass ratio of liquid to solid ratio 2∶1,mass ratio of vanadium slag to manganese dioxide dosage 25∶0.9,microwave power 800W for 10 min.Results showed leaching based on microwave irradiation under pressure can shorten time 94.44% in comparison with that at atmospheric pressure,and the leaching extraction can improve about 20%.     

Production of biodiesel from palm fatty acid distillate using sulfonated-glucose solid acid catalyst:Characterization and optimization

A palm fatty acid distillate (PFAD) has been used for biodiesel production. An efficient sulfonated-glucose acid catalyst (SGAC) was prepared by sulfonation to catalyze the esterification reaction. The effect of three variables i.e. methanol-to-PFAD molar ratio, catalyst amount and reaction time, on the yield of PFAD esters was studied by the response surface methodology (RSM). The optimum reaction conditions were:12.2:1 methanol-to-PFAD molar ratio, 2.9%catalyst concentration and 134 min of time as predicted by the RSM. The reaction under the optimum conditions resulted in 94.5%of the free fatty acid (FFA) conversion with 92.4%of the FAME yield. The properties of the PFAD esters were determined according to biodiesel standards.     

Kinetics of Sawdust Hydrolysis with Dilute Hydrochloric Acid and Ferrous Chloride

With dilute hydrochloric acid as catalyst and promoted by ferrous chloride, hydrolysis of waste sawdust to produce monosaccharides was conducted by using an one-step method in a batch-wise operation reactor. Based on the model of first order consecutive irreversible reactions, the kinetics equation incorporating the term of catalyst concentration was obtained that is suitable for describing the hydrolysis of sawdust. Activation energies were calculated for hydrolysis of sawdust and decomposition of monosaccharides.     

Preparation of Peracetic Acid from Acetic Acid and Hydrogen Peroxide: Experimentation and Modeling

Based on the kinetic equations and equilibrium constants, some mathematic models were developed for calculating peracetic acid (PAA) concentration, equilibrium conversion rate of hydrogen peroxide, etc. The effects of several parameters on PAA synthesis were investigated by experimentation and modeling. The equilibrium constants determined from the forward and reverse rate constants at 293, 303, 313 and 323 K were 2.91, 2.81, 2.72 and 2.63, respectively. The models could predict the values of equilibrium concentration of PAA with average relative deviation of less than 10%. Both of the experimental and model-calculated results demonstrated that temperature and catalyst loading were the most important factors affecting the rate of PAA synthesis, but high temperature led to the decrease of equilibrium concentration of PAA. According to the model, the reaction could achieve equilibrium within 24 h when operated at 303 K with 1%~1.5%(w) sulfuric acid as catalyst. Additionally, when using anhydrous acetic acid and 30% hydrogen peroxide to prepare PAA, the volumetric ratio of the two solutions should be in the range of 1.2~1.5 in order to obtain the highest equilibrium concentration of PAA. This study can serve as a step towards the further optimization of PAA synthesis and some other related investigations.     

TEOS-化学液相沉积法改性ZSM-5催化剂上的高选择性甲苯择形歧化反应

Shape-selective catalysts for the disproportionation of toluene were prepared by the modification of the cylinder-shaped ZSM-5 zeolite extrudates with chemical liquid deposition with TEOS (tetraethyl orthosilicate).Various parameters for preparing catalysts were changed to investigate the suitable conditions.The resulting cata-lysts were tested in a pressured fixed bed reactor and characterized by SEM (scanning electron microscopy).The conversion of toluene and para-xylene selectivity were influenced remarkably by the n(SiO2)/n(Al2O3) ratio of ZSM-5 zeolite,the type and amount of deposition agent,acid and solvent used,and the time and cycle of deposition treatment.TEOS was proved to be a more efficient agent than the conventional polysiloxanes when the deposition amount was low.The catalyst prepared at the suitable conditions exhibited a high para-xylene selectivity of 91.1% with considerable high conversion of 25.6%.SEM analyses confirmed the formation of a layer of amorphous silica on the external surface of ZSM-5 zeolie crystals,which was responsible for the highly enhanced shape-selectivity.     

Adsorption of 2-naphthalenesulfonic acid/sulfuric acid/sulfurous acid from aqueous solution by iron-impregnated weakly basic resin:Equilibrium and model

Commercial grade weakly basic resin D301 was impregnated with iron through a simple method using ferric chloride. Experiments for single, bisolute and trinary competitive adsorption were carried out to investigate the adsorption behavior of 2-naphthalenesulfonic acid (NSA), sulfuric acid and sulfurous acid from their solution at 298K onto the novel hybrid iron impregnated D301(Fe-D301). Adsorption affinity of NSA on Fe-D301 was found to be much higher than that of sulfuric acid, while adsorption affinity of sulfuric acid was slightly higher than that of sulfurous acid. The data of single-solute adsorption were fitted to the Langmuir model and the Freundlich adsorption model. The non-ideal competitive adsorbed model coupled with the single-solute adsorp-tion models were used to predict the bisolute and trinary-solute competitive adsorption equilibria. The NICM coupled with the Langmuir model yields the favorable representation of the bisolute and trinary-solute compet-itive adsorption behavior.     

2-甲基-6-乙酰基萘液相催化氧化反应动力学

In this paper,a kinetics model for the liquid-phase oxidation of 2-methyl-6-acetyl-naphthalene to 2,6-naphthalene dicarboxylic acid catalyzed by cobalt-manganese-bromide is proposed.The effects of the reaction temperature,catalyst concentration and ratio of catalyst on the time evolution of the experimental concentration for the constituents including raw material,intermediates and product are investigated.The model parameters are determined in a nonlinear optimization,minimizing the difference between the simulated and experimental time evolution of the product composition obtained in a semi-batch oxidation reactor where the gas and liquid phase were well mixed.The kinetics data demonstrate that the model is suitable to the liquid-phase oxidation of 2-methyl-6-acetyl-naphthalene to 2,6-naphthalene dicarboxylic acid.     

沙柳酸催化水解制备乙酰丙酸及分离提纯

以沙柳为原料,硫酸为催化剂,考察了催化剂浓度、反应时间、反应温度、液固比对沙柳水解制备乙酰丙酸得率的影响,通过正交实验方法得到最佳的水解反应条件为：反应温度200 ℃,反应时间90 min,催化剂质量分数9%,液固比（mL∶g）15∶1,乙酰丙酸的最高得率为18.80%;各因素对水解反应影响的大小顺序为：反应时间＞催化剂浓度＞反应温度＞液固比。在静态条件下,用335弱碱性阴离子交换树脂对水解液进行分离提纯,在附吸温度为35 ℃、树脂投料量为15 g、盐酸洗脱剂浓度为0.5 mol/L时,乙酰丙酸的回收率为95.35%。     

木糖渣稀酸水解制取还原糖条件的研究

在高温条件下通过对木糖渣稀硫酸水解的研究,探讨了影响水解还原糖产率的因素如固液比、硫酸浓度、时间和温度,得到了水解还原糖的较优条件是固液比为1：15（质量体积比）,硫酸浓度为8%,反应温度为120℃,反应时间为120min。在此条件下,得到还原糖产率为45.6%。证明通过稀酸水解处理木糖渣是一条重要和环境友好型的途径。     

江西弋阳蛇纹石硫酸浸出过程工艺条件的优化研究

文章在常压、较低温度(<100℃)下,开展了江西弋阳蛇纹石硫酸浸出工艺条件的研究.以蛇纹石中氧化镁的浸出率为主要考察指标,通过单因素条件实验和正交实验,分别考察了蛇纹石酸浸反应温度、酸浸反应时间、硫酸溶液质量浓度、液固比等因素的变化对蛇纹石中氧化镁浸出率的影响,所得较佳的工艺条件为:酸浸反应温度95℃、酸浸反应时间5h...     

半乳糖常压水解制备乙酰丙酸

以半乳糖为原料,常压下硫酸催化水解制备乙酰丙酸,探讨了半乳糖浓度、反应温度、反应时间、硫酸浓度等对乙酰丙酸产率的影响.结果表明,硫酸催化水解制乙酰丙酸的最优反应条件为:半乳糖浓度0.4 mol·L-1、反应温度130℃、反应时间60 min、硫酸浓度3.5 mol·L-1,在此条件下,乙酰丙酸产率最高达到64.2％.     

用硫酸从镍氢电池负极板废料中浸出镍钴

为了吲收有价金属,实现废物循环利用,对硫酸浸出镍氢电池负极扳废料中的镍钻元素进行了生产性试验研究。基于硫酸与负极板反应放出大量热量及产生大量气体的原理,采用涂层钢带一体、静态不施加搅拌的浸出方式,考察了硫酸浓度、液固比（硫酸体积与负极板废料的质量比）、反应时间、温度等因素对镍钴浸出的影响。生产性试验结果表明：在硫酸浓度为2．0mol／L、液固比为6：1、反应时间为30min、初始温度为常温的条件下,镍钴浸出率均在98％以上,稀土浸出率在90％以上,铁浸出率只有3％～6％。     

废旧镍氢电池负极材料中镍的提取技术研究

采用动态溶出法研究了废旧镍氢电池中金属镍的湿法回收工艺。分别考察了硫酸浓度、液固比、溶解时间、温度等因素对废旧镍氢电池负极材料中镍的回收率的影响。实验结果表明,当硫酸浓度为3 mol/L,液固比为7∶1,溶解时间为5 h,溶解温度为70℃时,镍的回收率达到最高。最佳条件下,镍的回收率为98%。     

硫酸水解-高效液相色谱法定量测定低聚木糖

建立了一种基于硫酸水解-高效液相色谱法测定低聚木糖产品中低聚木糖含量的简捷方法。经过优化实验,硫酸水解的条件:硫酸质量分数6.0%、反应温度100℃、反应时间60 min;高效液相色谱测定的条件:色谱柱Bio-Rad Aminex HPX-87H、流动相5 mmol/L H₂SO₄、洗脱流速0.6 mL/min、柱温55℃,采用外标法和峰面积积分法测得样品中低聚木糖质量分数为39.94%,重复性好,标准差为0.36%。     

煤气化粉煤灰酸浸工艺条件的研究

在常压、较低温度（≤100℃）下,开展了煤气化粉灰硫酸浸出工艺条件的研究。以煤气化粉煤灰中Al2O3的浸出率为主要考察指标,通过单因素条件实验和正交实验,分别考察了粉煤灰活化焙烧温度、酸浸反应温度、酸浸反应时间、硫酸溶液质量浓度、液固比等因素的变化对煤气化粉煤灰中Al2O3浸出率的影响。在无需活化焙烧、不使用助剂的条件下,确定较适宜的酸浸工艺条件为：酸浸反应温度95℃、酸浸反应时间5h、硫酸溶液质量浓度40％、液固比4．5：1;此条件下的重复实验表明煤气化粉煤灰中Al2O3的平均浸出率为94．87％。     

杨木废弃物稀酸水解预处理条件的响应面优化

以聚糖类转化率为考核指标,探讨了杨木废弃物稀酸水解预处理物料的适宜颗粒尺寸范围,并用响应面实验设计优化了稀酸水解条件.结果表明,稀酸水解预处理物料的适宜颗粒尺寸为0.075~0.096 mm,稀硫酸水解的优化工艺条件为:固液比1:10,温度158 ℃,时间5 min,硫酸质量分数2.5%.在此优化条件下,聚糖类转化率为59.23%.稀酸水解液的高效液相色谱分析表明,水解液主要成分为木糖(29.897 g/L),占总糖量的64.8%,其次为葡萄糖(8.748 g/L),占总糖量的18.9%,稀酸水解单糖继续降解较少.SEM形貌和XRD分析表明,水解残渣的纤维结构破坏明显,其结晶度由原料的57.45%降低到47.37%,该稀酸水解残渣存在通过酶解和发酵制备生物乙醇的可能性.     

钒铅锌矿硫酸浸出提取钒锌

钒铅锌矿含有多种有价金属,V品位高,具有较高的经济价值。本工作采用硫酸浸出法从该矿中提取钒锌,对浸出过程热力学进行分析,通过条件实验研究硫酸浓度、液固比、浸出时间、搅拌速率、浸出温度等条件对钒、铅、锌等主要有价金属浸出率的影响。结果表明,在较高pH值及较高温度下,浸出液中V会出现水解,含V的水解产物留在浸出渣中影响V浸出率。得到最优浸出条件为：硫酸浓度200 g/L,液固比3:1,浸出时间30 min,搅拌速率200 r/min,浸出温度为30℃。最优条件下V浸出率可达97.90%,Zn浸出率为97.11%,Fe浸出率<1%,Pb浸出率<0.01%。动力学分析结果表明,浸出过程的反应速率受扩散过程控制。酸浸过程使V和Zn进入浸出液,Pb和Fe留在浸出渣中,所得浸出液可使用离子交换或萃取法分离V和Zn。浸出渣中含钒0.41wt%、锌0.61wt%、铁15.50wt%、铅47.70wt%,主要成分为PbSO₄和FeO(OH),可返回火法炼铅系统。