Selective hydrogenolysis of glycerol to 1,3-propanediol over Pt-W based catalysts

The selective hydrogenolysis of glycerol to 1,3-propanediol(1,3-PDO)is an attractive reaction due to the high demand for valorization of huge excess amounts of glycerol supply as well as the important application of 1,3-PDO in polyester industry.Nevertheless,the formation of 1,3-PDO is thermodynamically less favorable than 1,2-PDO,which necessitates the development of efficient catalysts to manipulate the reaction kinetics towards the 1,3-PDO formation.Among others,Pt-W based catalysts have shown promising activities and selectivities of 1,3-PDO although the reaction mechanism is not well addressed at the molecular level.In this short review,we have compared the performances of different Pt-W based catalysts and discussed the key factors influencing the activity and selectivity.Three possible reaction mechanisms have been discussed in terms of the synergy between Pt and WO_x and the origin of acid sites.Finally,the long-term stability of the Pt-W catalysts has been discussed.We hope this review will provide useful information for the development of more efficient catalysts for this important reaction.

Effective and simple recovery of 1,3-propanediol from a fermented medium by liquid–liquid extraction system with ethanol and K_3PO_4

1,3-Propanediol,traditionally obtained from fossils,has numerous industrial applications,including use in the production of high performance polymers.The microbial production of 1,3-propanediol presents several opportunities,and the final purity grade determines its price and commercial viability.The development of novel separation technology could improve the economic viability of the bioproduction of 1,3-propanediol.Thus,we investigated salting-out extraction as a novel process for 1,3-propanediol recovery from fermentation broth.Initially,a screening for the best salt/solvent combination was conducted and then optimized using the response surface methodology.The solvents studied were methanol,ethanol,isopropanol and acetone,and the salts examined were K_2HPO_4,Na_2CO_3,K_2CO_3,(NH_4)_2SO_4,NaHPO_4,K_3PO_4 and C_6H_5NaO_7.The optimal extraction system consisted of 34 wt%K_3PO_4,28 wt% ethanol,and 38 wt% fermentation broth containing 23.0 g·L^(-1)1,3-propanediol,which gave the highest partition coefficient of 33 and recovery yield of 97%.The results demonstrated that salting-out extraction was a promising method for 1,3-propanediol recovery from fermentation broth.

Aqueous Two Phase Extraction for the Recovery of 1,3-Propanediol from Its Aqueous Solutions

As the biodiesel production is rapidly enhanced, the crude glycerol, which is by-product of biodiesel processes, is state of surplus. 1,3-PDO (1,3-propanediol), a valuable monomer of poly(trimethylene terephthalate) (PTT), can be produced from the fermentation process using crude glycerin as a carbon source. For the economic biological production of 1,3-PDO, the low cost and high efficient separation processes is essential. In this study, aqueous two-phase system composed of various hydrophilic alcohols and salt was used as a primary separation step for 1,3-PDO. It was found that the aqueous two-phase systems are easily formed with decreasing of the polarity of alcohols. The extraction efficiency is proportional to the polarity of alcohols. In case of methanol or ethanol/K2HPO4, the extraction efficiency was more than 90%.? It was concluded that the aqueous two-phase extraction using methanol or ethanol/K2HPO4 can be applied? for the primary separation of 1,3-PDO? as an alternative to a conventional primary separation processes.

Isolation and Identification of Alkali-Resistant 1,3-Propanediol Producing Strain

1,3-Propanediol is a promising renewable resource produced by microbial production. It is mainly used in many synthetic reactions, particularly applied to the polymer synthesis and cosmetics industry. We described here the isolation of strain ZH-1, which has the ability of high production with 1,3-propanediol, from Fenhe River in China. It was classified as a member of K. pneumoniae after the study of phenotypic, physio-logical, biochemical and phylogenetic (16S rDNA). The initial glycerol concentration, fermentation time and pH value of strain ZH-1 were determined to be 50 g·L-1, 36 h and 8.0. Under these conditions, the practical yield of 1,3-PD was 18.53 g·L-1 and a molar yield (mol1,3-PD molGlycerol-1 of 1,3-propanediol to glycerol of 0.497. In addition, we found that for the strain ZH-1, the optimum grown pH was 9.0, so we can deter-mine that it is a new member of alkali-resistant strains.

Isolation of New Strains of Bacteria Able to Synthesize 1,3-Propanediol from Glycerol

The natural environment is inhabited by many species that exhibit very specific metabolic activities that may find industrial applications. The aim of the study was to select non-pathogenic cultures of bacteria of the genus Clostridium and lactic acid bacteria able to convert glycerol into 1,3-propanediol (1,3-PD). Another aim of this study was to identify the isolates that best produced 1,3-propanediol both from pure and crude glycerol. The most efficient strains identified (Cl. butyricum) were analysed on a bioreactor scale. The aim was to determine temperature conditions on the efficiency and duration of 1,3-PD synthesis. The species Clostridium were identified using amplification of the 16S rRNA coding sequence. A total of 123 isolates (of the genus Clostridium and lactic acid bacteria) were isolated;a vast majority of these were able to synthesize 1,3-PD. The best results were obtained for Cl. butyricum strain DSP1, which was isolated from the rumen of a cow fed with glycerol. The strain efficiency using pure glycerol on bioreactor scale 0.65 mol/mol of glycerol at a temperature of 38℃ and a constant pH of 7.0.

梯度洗脱高效液相色谱法快速测定1,3-丙二醇发酵液中有机酸

提出了一种快速分析发酵液中9种有机酸的高效液相色谱方法。该方法利用RSpakKC-811色谱柱(300mm×8mmi.d.),采用超纯水-4mmol/L高氯酸为流动相进行梯度洗脱。流动相流速1.0mL/min,紫外检测波长210nm,柱温60℃时,能够快速、准确地分离测定发酵液中的丙酮酸、柠檬酸、苹果酸、延胡索酸、琥珀酸、乳酸、甲酸、乙酸等8种有机酸,分析时间只需15min。各种有机酸的线性相关系数R2≥0.9992,精密度的相对标准偏差为0.97%-2.72%,样品回收率为96.8%-102.5%,具有较高的精密度和准确度,可以用于1,3-丙二醇发酵液中有机酸的分析。

发酵液中1,3-丙二醇分离提取的研究进展

1,3-丙二醇是合成聚乳酸的主要原料,以甘油为底物的生物法制备1,3-丙二醇是以绿色化学为特征的技术。但1,3-丙二醇极性很强、微生物发酵液成分较复杂,产品收率偏低,质量难符合制备高性能聚对苯二甲酸丙二醇酯的要求,故1,3-丙二醇的分离提纯成为了生物法合成技术的关键。对于1,3-丙二醇发酵液,提纯过程包括发酵液预处理、脱盐和浓缩提纯。本文讨论了用于1,3-丙二醇提纯的主要技术,包括采用离心、过滤、絮凝脱大分子物质,用离子交换、电渗析、双水相萃取或有机溶剂沉淀等方法脱盐类,及通过精馏、萃取、吸附对发酵液浓缩提纯,或是以上某几个分离工艺的组合。提出整个分离工艺仍存在很多问题,对各工艺路线不断进行优化,开发新的经济高效的分离提取工艺路线,是目前实现规模化生物法生产1,3-丙二醇的技术重点。

1,3-丙二醇发酵液的絮凝预处理研究

【目的】对含1，3-丙二醇的发酵液进行絮凝预处理研究。【方法】实验采用三种阳离子型聚丙烯酰胶（以下简称CPAM）作为絮凝剂去除含1，3-丙二醇发酵液中的菌体和蛋白质大分子杂志。考察不同条件下的絮凝处理对发酵液中1，3-丙二醇和过滤效果的影响。【结果】实验研究得到适宜的1，3-丙二醇的发酵液絮凝条件：采用F04800SH型阳离子型聚丙烯酰胺，絮凝剂用量0．2g／L，pH7．0～11．0，搅拌速度200dmin，温度15℃～60℃，该条件下预处理的发酵液絮凝率大于95％，絮凝率超过95％。【结论】实验研究确定的絮凝预处理不会造成1，3-丙二醇的损失且能加快过滤速度，是一种有效的1，3-丙二醇发酵液预处理方法。

酵母发酵液直接催化4-氯-乙酰乙酸乙酯不对称还原生成4-氯-3-羟基-丁酸乙酯

考察了面包酵母发酵液直接催化4-氯-乙酰乙酸乙酯（COBE）的不对称还原反应,并进行了手性添加物的筛选和反应条件的优化实验. 结果表明,以β-环糊精为手性添加物时,酵母发酵液催化COBE不对称还原生成光活性产物（S）-4-氯-3-羟基-丁酸乙酯（（S）-CHBE）的产率和ee值分别高达76%和92%. 在一定条件下,增大β-环糊精浓度,有利于（S）-CHBE的生成. 最佳酵母菌培养时间为16～18 h, 最佳反应温度和pH值分别为29～31 ℃和7.2.

1,3-丙二醇发酵液脱盐技术研究进展

1,3-丙二醇（PDO）是新型纤维PTT的关键原料,可通过化学法和生物发酵法生产,在生物发酵法生产PDO过程中,菌体代谢过程产生有机酸,发酵过程通过自控流加液碱调节发酵液pH值为中性,发酵结束时发酵液液中有2%-3%的盐,目前PDO发酵液脱盐的技术有离子交换、电渗析、双极膜电渗析、刮板蒸发等,本文对这几种脱盐技术进行了综述和比较,为该领域的从业人员提供参考。

酵母发酵液催化不对称还原反应合成(S)-4-氯-3-羟基-丁酸乙酯的条件优化

目的优化酵母发酵液直接催化4-氯乙酰乙酸乙酯(COBE)合成(S)-4-氯-3-羟基-丁酸乙酯((S)-CHBE)的反应条件.方法考察酵母发酵液催化该反应过程中基质变化的规律,研究底物和能源供体对反应的影响,并通过正交实验设计法优化反应条件.结果在酵母发酵液催化COBE不对称还原反应的过程中,底物和还原糖消耗、产物合成相对集中在反应的前期;反复分批式添加底物和蔗糖有利于反应效率的提高;正交实验优化反应条件的结果表明酵母发酵液直接催化COBE不对称还原反应合成(S)-CHBE的最佳反应条件为蔗糖添加方式Ⅱ(反应开始2h后添加5g/120mL),底物添加方式Ⅳ[0.5(3)],缓冲剂添加量2g/120mL,β-环糊精添加量为2g/120mL,反应后测定产物的产率达96%,ee(对映体过量值)达100%.结论通过反应条件优化提高了酵母发酵液的催化效果.

对1,3-丙二醇发酵液用金属纳滤膜过滤的研究

考察了l,3-丙二醇发酵液金属膜过滤在不同条件下的通量、收率及蛋白含量的变化。在此基础上,初步探讨了膜的过滤机理,确定了金属膜过滤的工艺参数。结果表明,100 nm膜适用于过滤1,3-丙二醇发酵液,按料液体积20%从开始过滤2h后就持续加入去离子水,在4.2/3.6 MPa压力下,60℃,pH值为7的条件下,5h内完成过滤,并且收率达到87%以上,运行时间短而且对后续工艺压力最小。

高效液相色谱法检测肺炎克雷伯氏菌发酵液中的3-羟基丙酸

3-羟基丙酸(3-hydroxypropionic acid,3-HP)是一种重要的平台化合物。肺炎克雷伯氏菌(Klebsiella pneumoniae)利用甘油生产3-HP的过程中,常伴有乳酸等副产物的产生。在利用高效液相色谱法(high performance liquid chromatography,HPLC)检测3-HP产量时,两者色谱峰重叠、难以有效检测3-HP产量。因此,通过选择与优化HPLC的检测条件,建立了一种简单、快速、准确检测3-HP含量的检测方法。结果表明:利用色谱柱HPX-87H(300 mm×7.8 mm,5μm),流动相5 mmol·L^(-1)H_(2)SO_(4),流速0.6 mL·min^(-1),柱温65℃,进样量20μL,采用紫外检测器(210 nm),完成了3-HP产量的检测。该方法不仅提高了3-HP的检测效率和检测精度,还可以准确检测发酵过程中产物的变化。

Optimizing Control of Bio-dissimilation Process of Glycerol to 1,3-Propanedlol

An iterative optimization strategy is proposed and applied to the steady state optimizing control of the bio-dissimilation process of glycerol to 1,3-propanediol in the presence of model-plant mismatch and input constraints. The scheme is based on the Augmented Integrated System Optimization and Parameter Estimation （AI- SOPE） technique, but a linearization of some performance function in the modified model-based optimization problem of AISOPE is introduced to overcome the difficulty of determining an appropriate penalty parameter. When carrying out the iterative optimization, the penalty coefficient is set to a larger value at the current iteration than at the previous iteration, which can promote the evolution rate of the iterative optimization. Simulation studies illustrate the potential ofthe approach presented for the optimizing control of the bioTdissimilation process of glycerol to 1,3-propanediol. The effects of measurement noise, measured and unmeasured disturbances on the proposed algorithm are also investigated.

在线反冲在1,3-丙二醇发酵液膜过滤中的应用

膜过滤是生物法1,3-丙二醇(PDO)分离提取工艺中的关键工序,膜污染是影响膜过滤通量和清洗水用量的核心因素,在膜过滤过程中增加在线反冲,可以有效降低膜污染对过滤通量的影响,减缓膜过滤通量下降的速度,将膜过滤设备清洗周期由1d/次延长至5d/次。

Alcohol-treated SiO_2 as the support of Ir-Re/SiO_2 catalysts for glycerol hydrogenolysis

The surface of SiO2 support was pretreated by C1-C4 normal alcohols before the impregnation of iridium and rhenium precursors.These catalysts were applied in high concentration glycerol aqueous solution hydrogenolysis.The catalysts prepared from the pretreated supports exhibited high catalytic activity because of the formation of more active sites from a high dispersion of iridium oxide and rhenium oxide.The catalysts with the support pretreated by 1-propanol showed the highest glycerol conversion of 59.5%.The supports and catalysts were characterized by FT-IR,nitrogen adsorption,TPR,XRD,TEM,H2-chemisorption and NH3-TPD.

Effect of promoters on the selective hydrogenolysis of glycerol over Pt/W-containing catalysts

Diverse promoters,including noble metals（such as Ru,Ir and Rh） and transition metal oxides（such as Re,La,Fe,Zr,Sn and Ce oxides） were introduced into Pt/WOx and Pt/WOx/Al2O3 catalysts to investigate the ability of these promoters to modify activity and selectivity during glycerol hydrogenolysis to 1,3-propanediol.Among these,La exhibited the greatest promotional effect;the introduction of 0.1% La to the Pt/WOx improved activity,selectivity and stability,although the significant increase in selectivity came at the cost of a slight activity loss in the case of the Pt/WOx/Al2O3 catalyst.Transmission electron microscopy,high angle annular dark field scanning tunneling electron microscopy and NH3-temperature programmed desorption all demonstrated that the introduction of La generates a greater quantity of acidic sites on the catalyst surface,and that the majority of the La species are associated with Pt particles.Most of the other additives resulted in only minimal improvements or even detrimental effects with regard to both activity and selectivity,although some appear to improve the stability of the catalyst.

Adsorption of 1,3-propanediol from synthetic mixture using polymeric resin as adsorbents

The aim of this work was to separate 1,3-PDO from a synthetic mixture using polymeric resins,Amberlite XAD-7 and XAD-16 resins.The equilibrium adsorption of 1,3-PDO onto two polymeric resins were investigated in binary and tertiary systems.Experimental results of binary component adsorption equilibrium indicated that the adsorption capacity(q)of 1,3-PDO at 160 g/L onto XAD-7 and XAD-16 was 835.96 and 584.61 mg 1,3-PDO/g dry resin,respectively.The adsorption isotherms were closely predicted by the Langmuir-Freundlich model among the two isotherm model tested.The value of n of 1,3-PDO adsorbed on XAD-7 are much higher than those on XAD-16.This result suggested that XAD-7 resin has a higher affinity for the 1,3-PDO adsorption than XAD-16 resin.Moreover,the value of adsorption capacity of 1,3-PDO in the binary and tertiary component were compared at the same conditions.In the tertiary system,although the selectivity of 1,3-PDO from XAD-7 was approximately six times higher than XAD-16,the adsorption capacity of 1,3-PDO at 160 g/L onto XAD-16 was higher than XAD-7.Interestingly,the reusability of XAD-7 and XAD-16 resins in the three cycle times shows a slight loss of adsorption capacity.Furthermore,the investigation about desorption by an ethanol/water mixture at 50%(V/V)indicated that the desorption yield of 1,3-PDO from XAD-7 was lower than XAD-16 resin for both the binary and tertiary component.This was due to the more favorable adsorption characteristics of XAD-7 resin than XAD-16 resin.

Thermodynamic analysis of liquid phase in situ hydrogenation of glycerol for 1,3-propanediol synthesis

Based on the combination of the glycerol aqueous-phase reforming(APR)and catalytic hydrogenation of glycerol,a novel reaction system of liquid phase in situ hydrogenation of glycerol for the synthesis of 1,3-propanediol is proposed,in which hydrogen is produced from glycerol aqueous-phase reforming in the same reactor.In this new system,the glycerol is the raw material of the aqueous-phase reforming reaction;the hydrogen generated from the APR of glycerol can be quickly transformed to the in situ hydrogenation of glycerol to produce 1,3-propanediol,which can improve the selectivity of hydrogen for the APR process of glycerol.Moreover,thermodynamic calculation of the coupling processes was carried out,and standard molar enthalpies and equilibrium constants of foregoing reactions were obtained.The above calculation results indicate that the combination process is feasible for 1,3-propanediol synthesis.

Separation of 1,3-propanediol from glycerol-based fermentations of Klebsiella pneumoniae by alcohol precipitation and dilution crystallization

The separation of 1,3-propanediol from the glycerol-based fermentation broth of Klebsiella pneumoniae plays an important role during the microbial production of 1,3-propanediol.In this paper,the separation of 1,3-propanediol from fermentative broth by a combination of ultrafiltration and alcohol dilution crystallization was investi-gated.The broth was first filtered by ultrafiltration,and 99%of cells,89.4%of proteins and 69%of nucleic acids were removed.The obtained broth was further condensed by vacuum distillation,and then alcohol was added.The macro-molecular impurities,such as nucleic acids,polysaccharides and proteins,were precipitated,and inorganic and organic salts were crystallized.The optimal volume ratio of alcohol added to the condensed fermentation broth was determined to be 2:1.As a result,proteins,nucleic acids and electric conduc-tivity decreased by 97.4%,89.7%and 95.8%,respectively,compared with the fermentative broth.The influences of pH and water content in condensed broth on alcohol precipi-tation and dilution crystallization were also investigated.The experimental results indicated that alcohol precipitation and dilution crystallization was feasible and effective for the separation of 1,3-propanediol from actual fermentation broth.