Kinetics of Hydrogenolysis of Glycerol to Propylene Glycol over Cu-ZnO-Al2O3 Catalysts

A series of Cu-ZnO-Al2O3 catalysts with various metal compositions of Cu/Zn/Al were prepared by the co-precipitation method,and screened for glycerol hydrogenolysis to propylene glycol.The catalyst with a Cu/Zn/Al molar ratio of 1:1:0.5 exhibited the best performance for glycerol hydrogenolysis,and thus selected for kinetic investigation.Under elimination of external and internal diffusion limitation,kinetic experiments were performed in an isothermal fixed-bed reactor at a hydrogen pressure range of 3.0-5.0 MPa and a temperature range of 493-513 K. Based on a dehydration-hydrogenation two-step hydrogenolysis mechanism,a two-site Langmuir-Hinshelwood kinetic model taking into account competitive adsorption of glycerol,acetol and propylene glycol was proposed and successfully fitted to the experimental data.The average relative errors between observed and predicted outlet concentrations of glycerol and propylene glycol were 6.3%and 7.6%,respectively.The kinetic and adsorption parameters were estimated by using the fourth-order Runge-Kutta method together with the Rosenbrock algorithm.The activation energies for dehydration and hydrogenation reactions were 86.56 and 57.80 kJ·mol-1,respectively.

Effects of Oral Administration of Propylene Glycol and Ca-P-Mg Mixture on Milk Quality and SCC of Dairy Cows after Birth

In order to further study the postpartum care technology of dairy cows,the effects of oral administration of propylene glycol or Ca-P-Mg mixture and compound oral rehydration salts on milk quality and SCC of dairy cows after birth were investigated. The results showed that the milk fat and dry matter contents in the dairy cows administered with Ca-P-Mg mixture and compound oral rehydration salts were higher than those in the dairy cows administered with propylene glycol（P 〈0.05）. However, there were no significant differences in milk sugar and protein contents and SCC between the two administration groups.

Preparation and shaping of solid acid SO_4^(2-)/TiO_2 and its application for esterification of propylene glycol monomethyl ether and acetic acid

The solid acid SO_4^(2-)/TiO_2 was prepared by immersion method and applied for synthesis of propylene glycol methyl ether acetate(PMA) through esterification reaction of propylene glycol monomethyl ether(PM)and acetic acid(HAc). The optimal catalyst preparation condition was determined by orthogonal analysis of parameters in a five-factor and four-level test. The obtained solid acid catalysts were characterized in detail by means of X-ray powder diffraction, thermogravimetry, pyridine adsorbed IR analysis, scanning electron microscopy, and BET surface area method. Synthesis of PMA was studied in this paper through experimental investigation of reaction conditions such as temperature, molar ratio of reactants, catalyst dosage and agitation speed. Based on its possible reaction mechanism, a pseudo-homogeneous kinetic model was established and its activation energies E_a^+ and E_a^-,65.68 × 10~3J·mol^(-1) and 57.78 × 10~3J·mol^(-1), were estimated. To prepare shaped solid acid catalyst SO_4^(2-)/TiO_2, the shaping method of impregnation–shaping–impregnation was applied. The optimal molding formulation of solid acid catalyst, obtained from the orthogonal test, was found to be binder 7 wt%, reinforcing agent 20 wt%, pore forming material 2.5 wt%, and lubricant 4 wt%.The results of performance test of catalyst demonstrated that the shaped solid acid catalyst exhibited high activity and stability.

Synthesis of 2-methylpyrazine from cyclocondensation of ethylene diamine and propylene glycol over promoted copper catalyst

The 2-methylpyrazine was synthesized by catalytic reaction of ethylene diamine and propylene glycol at 380 ℃. The alumina supported copper catalysts with promoter were prepared by impregnation method, characterized by ICP-AES, BET and TPR. The results demonstrated that the dehydrogenation was improved by addition of chromium promoter. The selectivity of 2-methylpyrazine reached 84.75%, while the conversions of reactants were also enhanced.

Synthesis of propylene glycol ethers from propylene oxide catalyzed by environmentally friendly ionic liquids

A series of acetate ionic liquids were synthesized using a typical two‐step method.The ionic liquids were used as environmentally benign catalysts in the production of propylene glycol ethers from propylene oxide and alcohols under mild conditions.The basic strengths of the ionic liquids were evaluated by determination of their Hammett functions,obtained using ultraviolet‐visible spectroscopy,and the relationship between their catalytic activities and basicities was established.The catalytic efficiencies of the ionic liquids were higher than that of the traditional basic catalyst NaOH.This can be attributed to the involvement of a novel reaction mechanism when these ionic liquids are used.A possible electrophilic‐nucleophilic dual activation mechanism was proposed and confirmed using electrospray ionization quadrupole time‐of‐flight mass spectrometry.In addition,the effects of significant reaction parameters such as concentration of catalyst,molar ratio of alcohol to propylene oxide,reaction temperature,and steric hindrance of the alcohol were investigated in detail.

Zn–Ca–Al mixed oxide as efficient catalyst for synthesis of propylene carbonate from urea and 1,2-propylene glycol

A series of Zn–Ca–Al oxides with different CaO and ZnO contents have been prepared and evaluated in the synthesis of propylene carbonate(PC) from 1,2-propylene glycol(PG) and urea in a batch reactor. The effect of catalyst composition, basicity and reaction process parameters such as temperature, catalyst dose, molar ratio of PG to urea, purge gas flow and reaction time has been studied to find suitable reaction conditions for the PC synthesis. The PC selectivity and yield under the desired conditions could reach 98.4% and 90.8%, respectively. The best performing catalyst also exhibited a good reusability without appreciable loss in the PC selectivity and yield after five consecutive reaction runs. In addition, a stepwise reaction pathway involving a 2-hydroxypropyl carbamate intermediate was proposed for the urea alcoholysis to PC in the presence of Zn–Ca–Al catalysts, according to the time dependences of reaction intermediates and products.

IMPROVE OPTICAL CLEARING OF SKIN IN VITRO WITH PROPYLENE GLYCOL AS A PENETRATION ENHANCER

In order to enhance the optical clearing effect of topically applied optical clearing agents(OCAs),we evaluated the effect of propylene glycol(PG)as a chemical penetration enhancer(PE)on optical clearing of skin in vitro by observation and measurement of optical-transmittance and diffuse-reflectance spectra.Three OCAs,i.e.,glycerol,D-sorbitol and PEG400,and two other penetration enhancers,Azone and Thiazone,were used in this study.The results indicated that the decrease of reduced scattering coefficient caused by OCA/PG was larger than that by pure OCA,and the change by OCA/water was the least after the same treatment time.There were significant differences for the reduced scattering coefficient at 630 nm after 120 min application of agents between OCA and OCA/PG.The efficacy of optical clearing caused by OCA/PG depended on the OCA itself.When PEG400 was mixed with three different PEs,we found the optical clearing were different.The penetration enhancing ability of PG was much better compared to Azone,and suboptimal to Thiazone.Also,this study provides evidence for the use of PG as a PE in order to improve skin optical clearing.

Simulation and design of a heat-integrated double-effect reactive distillation process for propylene glycol methyl ether production

A double-effect reactive distillation(DERD)process was proposed for the production of propylene glycol methyl ether from propylene oxide and methanol to overcome the shortcoming of low selectivity and high-energy consumption in the tubular plug-flow reactor.A single-column reactive distillation(RD)process was conducted under optimized operating conditions based on sensitivity analysis as a reference.The results demonstrated that the proposed DERD process is able to achieve more than 95%selectivity of the desired product.After that,a design approach of the DERD process with an objective of the minimum operating cost was proposed to achieve further energy savings in the RD process.The proposed DERD configuration can provide a large energy-savings by totally utilization of the overhead vapor steam in the high-pressure RD column.A comparison of the single-column RD process revealed that the proposed DERD process can reduce the operating cost and the total annual cost of 25.3%and 30.7%,respectively,even though the total capital cost of DERD process is larger than that of the RD process.

Preparation, Characterization and Pharmacokinetics of Fluorescence Labeled Propylene Glycol Alginate Sodium Sulfate

A rapid and sensitive fluorescence labeling method was developed and validated for the microanalysis of a sulfated polysaccharide drug,namely propylene glycol alginate sodium sulfate(PSS), in rat plasma. Fluorescein isothiocyanate(FITC) was selected to label PSS, and 1, 6-diaminohexane was used to link PSS and FITC in order to prepare FITC-labeled PSS(F-PSS) through a reductive amination reaction. F-PSS was identified by UV-Vis, FT-IR and 1H-NMR spectrum. The cell stability and cytotoxicity of F-PSS were tested in Madin-Darby canine kidney(MDCK) cells. The results indicated that the labeling efficiency of F-PSS was 0.522% ± 0.0248% and the absolute bioavailability was 8.39%. F-PSS was stable in MDCK cells without obvious cytotoxicity. The method was sensitive and reliable; it showed a good linearity, precision, recovery and stability. The FITC labeling method can be applied to investigating the absorption and metabolism of PSS and other polysaccharides in biological samples.

Design and optimization of an integrated process for the purification of propylene oxide and the separation of propylene glycol by-product

It is difficult to separate the methanol and hydrocarbons in the propylene oxide(PO)purification process due to their forming azeotrope.As for this,a novel PO separation process,in that the deionized water is employed as extractant and 1,2-propylene glycol(MPG)that is formed from the PO hydrolysis reaction is recovered,is presented in this work.The salient feature of this process is that both the non-catalyzed reactions of PO hydrolysis to form MPG and dipropylene glycol(DPG)are simultaneously considered and MPG by-product with high purity is obtained in virtue of the deionized water as reflux liquid and side take-off in MPG column.In addition,the ionic liquid(IL)extractant is screened through the conductorlike screening model for segment activity coefficient(COSMO-SAC)and the comparisons of separation efficiency between the IL and normal octane(nC_(8))extractant for the separation of PO and 2-methylpentane are made.With the non-random two-liquid(NRTL)thermodynamic model,the simulation and optimization design for the full flow sheet are performed and the effects of the key operation parameters such as solvent ratio,theoretical stages,feeding stage etc.on separation efficiency are detailedly discussed.The results show that the mass purity and the mass yield of PO can be up to 99.99%and 99.0%,and the condenser duty,reboiler duty and PO loss in the process with IL extractant can be decreased by 69.66%,30.21%and 78.86%compared to ones with nC_(8).The total annual cost(TAC)calculation also suggests that the TAC would be significantly reduced if using IL in replace of nC_(8) for the investigated process.The presented results would provide a useful guide for improving the quality of PO product and the economic efficiency of industrial plant.

Stability and Thermal Property Optimization of Propylene Glycol-Based MWCNT Nanofluids

Propylene glycol-based MWCNT(multi-walled carbon nanotubes)nanofluids were prepared in the framework of a two-step method and by using a suitable PVP(polyvinyl pyrrolidone)dispersant.The BBD(Box-Behnken design)model was exploited to analyze 17 sets of experiments and examine the sensitivity of the absorbance to three parameters,namely the concentration of MWCNT,the SN ratio(mass ratio of carbon nanotubes to sur-factants)and the sonication time.The results have revealed that,while the SN ratio and concentration of MWCNT have a strong effect on the absorbance,the influence of the sonication time is less important.The sta-tistical method of analysis of variance(ANOVA)was further used to determine the F-and p-values of the model.Five experiments were run to validate this approach.Since sample 2 was found to display the greatest absorbance,it was selected for stability monitoring as well as thermal conductivity and viscosity measurements.This sample has been found to be stable;the viscosity decreased with increasing temperature;the addition of MWCNT nano-particles was more effective in improving the thermal conductivity of propylene glycol than other methods in the literature.Moreover,the MWCNT nanofluid based on propylene glycol exhibited higher thermal conductivity at low temperatures.

Manipulating Zn^(2+)solvation environment in poly(propylene glycol)-based aqueous Li^(+)/Zn^(2+)electrolytes for high-voltage hybrid ion batteries

Compared with aqueous single-ion batteries,rechargeable aqueous hybrid ion batteries,especially Li^(+)/Zn^(2+)hybrid ion batteries,are receiving extensive interest owing to their low cost,high operating voltage,and energy density.However,their working voltage and lifespan are limited by the decomposition of water and the growth of Zn dendrites.Herein,detrimental side reactions induced by the water reduction and the Zn dendrite growth are successfully suppressed by a poly(propylene glycol)(PPG)-based hybrid ion electrolyte[(1 m Zn(TFSI)2+10 m LiTFSI)in PPG/H2O].The addition of PPG in the electrolyte can not only enhance the bonding strength of hydrogen-bond in water but also tailor the solvation sheath of Zn2+as revealed by synchrotron X-rays.The participated solvation of PPG with Zn^(2+)can weaken Zn-H_(2)O interactions and redistribute Zn^(2+)flux on the surface of the Zn anode,thus inducing favorably even deposition of Zn.In addition,the decomposition of TFSI-contributes a ZnF_(2)-enriched solid electrolyte interface at the Zn anode to further prevent water decomposition and restrain Zn dendrites.The PPG-based electrolyte enables 2.1 V LiMnO_(2)//Zn batteries to deliver high specific capacities(121.7 mAh g^(-1)for a coin cell and 90 mAh g^(-1)for a pouch cell),and maintain 80%of the capacity over 700 cycles at 0.5 C,suggesting a promising pathway for highly reversible aqueous hybrid ion batteries.

Waste Management in Propylene Epoxidation Process with the Use of Supercritical Fluid Media

Experimental results on solubility of the styrene, phenol, methylphenylcarbinol, acetophenone, ethyl benzene, propylene glycol and molybdenum as a complex with Trilon B in supercritical CO2 obtained using a dynamic (flow) method are presented. The obtained data are described in the framework of Peng-Robinson equation. The results of the experients on the extraction of organic components from waste formed in the olefin epoxidation process at Nizhnekam-skneftekhim Inc., on the analysis of extract composition, and on the testing of the extract as an epoxidation catalyst are presented. The supercritical water oxidation (SCWO) process of epoxidation process waste was conducted in periodical and continuous mode. The analysis results of reaction product are given. Pilot experiments on dry sediment formation were conducted using Radio Frequency (RF) Inductively Coupled Plasma (ICP) of low pressure.

Chiral fluorescent sensor Tb^(3+)@Cd‑CP based on camphoric acid for the enantioselective recognition of R‑and S‑propylene glycol

Herein,a layered chiral coordination polymer,[Cd2(D‑cam)_(2)(2,2′‑bipy)_(2)]_(n)(Cd‑CP),was synthesized using a solvothermal method with camphoric acid(D‑H_(2)cam),2,2′‑bipyridine(2,2′‑bipy)and Cd^(2+),and Tb^(3+)@Cd‑CP was in‑situ synthesized introducing Tb^(3+)ions.The fluorescence experiments revealed that compared to Cd‑CP,Tb^(3+)@Cd‑CP exhibited ultra‑high fluorescence performance.The luminescence sensing performance demonstrated that Tb^(3+)@Cd‑CP could distinguish R/S‑propylene glycol(R/S‑PG)by fluorescence responses,with fluorescence quenching constant of 5.3×10^(3)and 2.0×10^(3)L·mol^(-1)respectively and the enantioselectivity factor(α)of 2.65.Moreover,Tb^(3+)@Cd‑CP demonstrated limits of detection of 9.3 and 19.0μmol·L^(-1)for R‑PG and S‑PG,respectively,and showed good reproducibility.

Oxidation of glycerol with H_2O_2 on Pb-promoted Pd/γ-Al_2O_3 catalysts

A series of bimetallic Pd-Pb catalysts with a constant Pd content of 1 wt%and Pb/Pd atomic ratio from 0 to 1.6 supported on γ-Al2O3 were prepared and used for glycerol oxidation with H2O2 as the oxidizing agent at atmospheric pressure,45℃ and pH =11.The morphology and dispersion of the catalysts were characterized by scanning electron microscopy-energy dispersive X-ray spectroscopy（SEM-EDX） and transmission electron microscopy（TEM）.The presence of an alloy phase in the bimetallic catalyst was detected by X-ray photoelectron spectroscopy（XPS）.Glycerol conversion obtained with the monometallic Pd catalyst was 19%,which was increased to 100%with the addition of Pb.The four bimetallic PdPb catalysts were able to oxidize glycerol to dihydroxyacetone（DIHA） and the selectivity to DIHA reached 59%,58%,34%and 25%for PdPb0.25,PdPb0.50,PdPb1.00 and PdPbl.60 catalysts,respectively.

Positive Effects of Isopropanol as a Co-Precipitant in Glycerol-3-Phosphate Acyltransferase Crystallization

Glycerol-3-phosphate acyltransferase(GPAT) is considered as the rate-limiting enzyme of glycerolipid synthesis pathway and the core element in lysophosphatidic acid(LPA) synthesis. For understanding its catalytic mechanism, the structural biology study is expected, but is always hindered by obtaining crystals for X-ray diffraction analysis. In this study, a progressive strategy to optimize the crystal of microalgae plastidial GPAT was presented. After the expression and purification of GPAT, the crystals were screened by hanging-drop and only clusters were obtained. The crystals were optimized by adjusting temperature, pH, protein concentration, or precipitant, but little improvement. To improve the interaction between protein and precipitant, the isopropanol was applied as co-precipitant. The qualified crystals formed. It's suggested that isopropanol is critical to affect protein crystallization by altering polyethylene glycol(PEG)-water-protein interaction when PEG serves as precipitant. The resulting crystal diffracted to a resolution of 2.75 ? and belonged to space group P1, with unit-cell parameters a = 50.79, b = 80.09, c = 88.21 ?, and α = 62.85, β = 73.04, γ = 80.53?. This work introduced a new strategy to optimize the crystal of the heterogeneous catalysis enzymes like GPAT and provided the fundamental structural information for the oriented synthesis of marine microalgae glycerolipid.

考虑丙二醇热解的相变发汗冷却数值研究

为了揭示裂解反应对相变发汗冷却的影响,本文结合局部热非平衡下的两相混合模型(LTNE-TPMM),过渡态理论(TST)和化学反应动力学,利用丙二醇(PG)作为冷却剂,对多孔平板相变发汗冷却进行了数值研究,首次揭示了不同冷却剂质量流量和热流密度分布下裂解反应对多孔介质内流动换热过程的影响机理和影响规律。结果表明,丙二醇裂解率与注入流量呈现负相关,与热流密度大小呈现正相关,质量流量从0.2 kg(/m^(2)∙s)提高至0.4 kg(/m^(2)∙s)时,丙二醇的裂解率由0.48降低至0.27;热流密度q_(0)从0.8 MW/m^(2)提高到1.2 MW/m^(2)时,裂解率由0.21提高到了0.63。裂解反应从多孔骨架吸收大量热量,增加了额外的化学热沉。此外,裂解反应能够有效强化多孔出口高温区的流动换热,提高热扩散速率。

负载碳酸钙的水包油包固乳液稳定性及相互作用研究

碳酸钙由于分散稳定性差,很难在食品基质中传递。水包油包固(solid-in-oil-in-water,S/O/W)三相载体乳液作为食品营养素的载体,具有制备成本低、工艺简单等优点。为提高碳酸钙在液态食品中的分散稳定性,实现较高品质利用,该文以黄原胶(xanthan gum,XG)和海藻酸丙二醇酯(propylene glycol alginate,PGA)复凝聚为水相,精制猪油为油相,通过高速剪切分散构建负载碳酸钙的S/O/W钙-脂质乳液,考察PGA和XG复凝聚的界面活性和相互作用,研究不同配比PGA-XG复合物制备乳液的物理稳定性、Zeta电位、表观黏度、粒径分布及微观结构。结果表明,PGA与XG以氢键的方式产生相互作用,复凝聚后显著降低了XG在油水界面的表面张力;m(PGA)∶m(XG)=4∶6时,乳液Zeta电位为(-43.3±0.1)mV,平均粒径为(1.59±0.08)μm,有较好的物理稳定性和流变学特性,碳酸钙位于油相内部。该研究结果可丰富构建S/O/W传递系统理论,为开发新型营养素输送载体提供参考。

双氧水法制环氧丙烷装置废水醇醚回收技术与经济效益分析

双氧水法制环氧丙烷装置(HPPO)废水具有排放总量大、化学需氧量(COD)高、含盐量高、可生化性差的特点。采用多级差压热耦合精馏技术、环保型可循环共沸精馏技术和MVR热泵精馏技术相结合,对HPPO废水进行醇醚回收,在低能耗的同时实现了HPPO废水中高附加值有机物总回收率95%以上,丙烯利用率提高3~5百分点,除盐率接近100%,大幅降低了后续废水处理的难度。在化工行业节能减排、降本增效的大背景下,具有显著的经济效益和社会效益。

聚醚酯消泡剂在白水中的性能研究

本研究表征了以不同官能度的聚醚(脂肪醇聚醚、丙二醇聚醚、甘油聚醚,官能度分别为1、2、3)和脂肪酸为原料合成的聚醚酯结构,着重探讨了3种官能度聚醚酯的消泡性能。结果表明,硬脂酸为优选脂肪酸,起始剂为十八醇、环氧乙烷(EO)与环氧丙烷(PO)物质的量比为3∶7时,合成的脂肪醇聚醚酯消泡剂的消泡性能最佳;POEO或EOPOEO嵌段的丙二醇聚醚酯(EO在聚醚链段末端)具有良好的消泡效果;相对分子质量3 000的甘油聚醚合成的甘油聚醚酯消抑泡效果最佳。优选的十八醇聚醚酯在低温生活用纸白水中消抑泡效果好,丙二醇聚醚酯和甘油聚醚酯分别在高温箱纸板和文化用纸白水中消抑泡效果好。3种聚醚酯溶液浓度增至0.6 g/L时,表面张力均为27.0 mN/m。