Production of olefins from ethanol by Fe and/or P‐modified H‐ZSM‐5 zeolite catalysts

BACKGROUND: Much attention has been paid to the catalytic conversion of ethanol to olefins, since biomass resources such as ethanol are carbon‐neutral and renewable, and olefins are useful as both fuels and chemicals. It has been reported that zeolite H‐ZSM‐5 is effective for converting ethanol to hydrocarbons, with the chief products being aromatic compounds. RESULTS: Successive addition of Fe and P to the H‐ZSM‐5 improved the initial selectivity for propylene, while the sole addition of Fe or P and co‐addition of Fe and P showed medium initial selectivity. In general, catalysts showing higher initial selectivity for propylene exhibited a steeper decrease in propylene selectivity with time on‐stream. The cause of the change in product selectivity may be carbon deposition during reaction. Addition of Fe and P can improve catalytic stability when processing both neat and aqueous ethanol. The catalytic performance was regenerated by calcination in flowing air. CONCLUSION: Fe‐ and/or P‐modified H‐ZSM‐5 zeolite catalysts efficiently produced olefins (especially propylene) from ethanol. Effective catalyst regeneration was achieved by calcination in flowing air. Copyright © 2010 Society of Chemical Industry     

Improvement in impact‐, tensile‐, and dynamic properties of injection molded wheat‐pulp‐polypropylene composites through fiber finishing

This study was focused on the improvement of mechanical properties of injection molded wheat‐pulp polypropylene (PP) composites through fiber surface modifications. Ten different sizing and finishing agents, including fats, starch derivatives, and polysiloxanes were used as surfactants for the cellulosic pulp. As a result of polydimethylsiloxane treatment (0.3 wt %), impact strength was increased by 85%, tensile strength by 23%, and an augmentation in tensile modulus of 12% was also achieved. In consideration of the dynamic mechanical properties, the stronger effects of the modifiers on the storage‐ modulus were observed with increasing temperature. A new approach quantifying the extent of the dispersion of the pulp fibers using image analysis through transmission light micrographs was tested. The enhancement of tensile strength, tensile modulus, and impact strength could be attributed to the improved dispersion of the cellulosic fibers. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

丙烷无氧脱氢制丙烯工艺和催化剂的研究进展

概述了目前已工业化的几种丙烷无氧脱氢制丙烯的技术,包括美国UOP公司的Olefl ex工艺、Lummus公司的Catofi n工艺、Krupp-Uhde公司的STAR工艺以及德国Linde-BASF公司的Linde工艺和Snamprogetti公司的FBD工艺。介绍了两种常用的丙烷无氧脱氢催化剂(Cr系和Pt系催化剂),简述了Cr系催化剂及其工艺,详述了Pt系催化剂的活性中心及脱氢机理及其改性的主要途径(加入助剂、改变催化剂载体和催化剂的制备方法等),并探讨了Pt系、Cr系催化剂的失活再生。最后对丙烷无氧脱氢反应及其催化剂的研究前景(包括反应机理、反应动力学、助剂的作用和催化剂的稳定性等)进行了展望。     

聚碳酸亚丙酯(PPC)加工热稳定性研究

可降解聚碳酸亚丙酯(PPC)加工热稳定性较差。采用高压毛细管流变仪、傅里叶红外光谱仪(FT-IR)、热失重仪(TG)、拉力机和色差仪对工业级PPC的加工热稳定性进行了系统测试和分析。结果表明,使用高压毛细管流变仪可以较好地评估PPC的加工热稳定性。热失重法可以评估PPC的加工热稳定性,但评估不同加工条件下或不同加工配方的PPC热稳定性灵敏度不高。其它方法均不适宜于评估该材料。本研究对PPC的加工有一定的指导作用,并为今后提高PPC加工热稳定性的研究提供技术支持。     

PA66短纤维用于提高聚甲基乙撑碳酸酯力学与热学性能的研究

聚甲基乙撑碳酸酯(PPC)分子间作用力较低、力学和热学性能较差,通过双螺杆挤出制备PPC/PA66短纤维复合材料,促进PA66短纤维与PPC形成氢键作用力,有利于提高PPC材料的综合性能。红外光谱分析结果表明PA66短纤维的羰基与PPC分子链中的羟基之间形成了氢键,PA66短纤维的引入提高了PPC的力学性能和热学性能。当短纤维含量为20%(质量分数)时,复合材料的缺口冲击强度提高了315.8%,初始分解温度和玻璃化温度分别提高了32.2和3.8℃。当短纤维含量继续增加至30%(质量分数)时,由于高含量的纤维之间容易发生团聚,导致复合材料的力学性能略有下降。PPC力学和热学性能的显著提高,主要原因是氢键作用力的形成和PA66短纤维受力后发生的拉丝形变所引起。     

Elastic liposomes-in-vehicle formulations destined for skin therapy: the synergy between type of liposomes and vehicle

Objective: The present study is focused on optimization of elastic liposomes-in-vehicle formulations in respect to drug release and formulation properties. By combining penetration potential of elastic liposomes containing high ratio of entrapped drug and physicochemical properties of vehicles, both affecting the release and texture properties, optimal formulation could be achieved.

Materials and methods: Deformable, propylene glycol-containing or conventional liposomes with hydrophilic model drug (diclofenac sodium) were incorporated into the following vehicles appropriate for skin application: a hydrogel, a cream base and derma membrane structure base cream (DMS base). Each formulation was assessed for in vitro drug release and mechanical properties.

Results and discussion: The composition and type of both liposomes and the vehicle affected the rate and amount of the released drug. The cream base exhibited the slowest release, followed by the hydrogel and DMS base. Similar release profiles were achieved with both types of elastic vesicles (deformable and propylene glycol liposomes); the slowest release was observed for conventional liposomes, regardless of the vehicle used. The drug release profiles from different liposomes-in-vehicle formulations were in agreement with the physicochemical properties of the formulations. All of the liposomes were found to be compatible with the hydrogel preserving its original textures, whereas a significant decrease in all texture parameters was observed for liposomes-in-DMS base, regardless of liposome type.

Conclusion: Propylene glycol liposomes-in-hydrogel is considered as the optimal formulation for improving skin delivery of hydrophilic drug. Further investigations involving in vivo animal studies are necessary to confirm its applicability in skin therapy.     

One platform comparison of solubilization potential of dendrimer with some solubilizing agents

Objective: To compare various solubilizing agents for their solubilizing propensity as well as effect of pH, concentration and time on solubility of a highly hydrophobic drug.

Materials and methods: Dendrimers were synthesized by divergent method. Solubilization studies were carried out at different pH, concentration and time using Paclitaxel (PTX) as model drug. Hemolytic toxicity study was also performed.

Results: The solubility of PTX was increased with increasing concentration of solubilizing agents and the order of solubility enhancement effect of different solubilizing agents was found to be in the following order: fifth generation (5.0?G) poly(propylene imine) (PPI) dendrimers?>?β-CD?>?Tween 80?>?polyethylene glycol 6000. The solubility of PTX was found to be highest at pH 5.0 followed by pH 7.4 than pH 9.2. The result of hemolytic toxicity studies displayed that when these solubilizing agents are given in combination with PTX, the toxicity was found to be reduced as compare to plain drug.

Conclusions: The solubility of PTX was found to be significantly higher in the presence of 5.0?G PPI dendrimers as compared to the other solubilizing agents. It is also concluded that 5.0?G PPI dendrimers not only enhanced the solubility of PTX many folds but also reduced the toxicity of PTX.     

Formulation and evaluation of clotrimazole transdermal spray

Context: Transdermal spray (TS) of clotrimazole (CTZ) was formulated to improve the drug transport through the skin up to 12?h to achieve the antifungal efficacy.

Objective: The aim of present study was to formulate and evaluate antifungal transdermal spray to improve the permeation of clotrimazole across the skin and to decrease the dosing frequency in fungal infection.

Materials and methods: Different ratios of ethanol and acetone and various grades of eudragit and ethyl cellulose were evaluated according to six criteria: viscosity, drying time, stickiness, appearance and integrity on skin and water washability. Propylene glycol (PG) and polyethylene glycol 400 (PEG 400) were used in the study as plasticizer and solubilizer. The TS was evaluated for in vitro drug release, spray angle, spray pattern, average weight per dose, pH, drug content, evaporation time, leak test and antifungal efficacy study.

Results and discussion: Eudragit E100 and blend of ethanol and acetone (80:20) satisfied the desired criteria. The selection of optimized batch was based on the results of in vitro drug release, spray pattern and spray angle. The optimized batch showed the spray angle <85° and uniform spray pattern. The formulation containing PG showed higher drug release than PEG 400. The inclusion of eutectic mixture consisting of camphor and menthol (1:1) showed improved drug transport through the rat skin and larger mean zone of inhibition indicating the improved antifungal efficacy.

Conclusion: The TS of CTZ can be an innovative and promising approach for the topical administration in the fungal diseases.     

Production and blood parameters of Holstein cows treated prepartum with sodium monensin or propylene glycol

Forty-five multiparous Holstein cows were assigned to one of 3 treatments in a randomized complete block design. The objective was to evaluate the effects of sodium monensin (M) and propylene glycol (PPG) during the prepartum period on performance and metabolic parameters during the late dry and first 9 wk postpartum for cows receiving M postpartum. Treatments were: control (C), M in a controlled-release capsule to deliver 335 +/- 33 mg/d for approximately 100 d, and 300 mL/d of PPG drenched orally. Treatments started at 35 and 21 d prior to the expected date of calving for cows receiving M and PPG, respectively. To ensure that all treatments would be restricted to the prepartum period, C and PPG cows received a M controlled-release capsule in the first 24 h after calving. Prepartum propylene glycol administration increased concentrations of glucose and insulin, and decreased beta-hydroxybutyrate and nonesterified fatty acids in plasma prepartum. Milk production was similarly affected by treatments. However, prepartum M treated cows tended to produce more 3.5% fat-corrected milk compared with control, but similar to PPG. Milk fat content and yield tended to be greater for cows that received M prepartum than for C cows, while PPG cows were similar to M and C. Prepartum administration of M decreased milk protein content, but no effect was observed on protein yield.     

XRD表征氯化镁乙醇醇合物的结构

制备了一系列乙醇与MgCl2摩尔比(简称醇镁比)不同的MgCl2醇合物,采用XRD方法研究了MgCl2醇合物的晶体结构,并通过对晶胞参数的计算分析了MgCl2醇合物中结构稳定的组分。表征结果显示,醇镁比在1.5~6之间的MgCl2醇合物有4种结构稳定的组分,分别为MgCl2·6EtOH,MgCl2·3.33EtOH,MgCl2·2.8EtOH,MgCl2·1.5EtOH。不同醇镁比的MgCl2醇合物是由这4种结构稳定的组分中的一种或几种组成的。