Cd/CdS光催化降解甲基橙的研究

采用胶体化学法制备表面富镉的Cd／CdS纳米粒子为催化剂对水溶液中甲基橙的光催化降解进行了研究。探讨了光催化反应机理,讨论了光催化剂用量,双氧水的用量,试液的pH值,光照时间与甲基橙脱色率的关系。实验结果表明,当甲基橙起始浓度为20mg／L,Cd／CdS用量为0．500g,双氧水用量为5．88mmol／L,pH值为7．0时,光照6h,甲基橙的脱色率可达到95．5％。     

纳米TiO2-MoO3的制备及对甲基红的催化降解

介绍了掺杂不同比例MoO3的纳米TiO2纳米混合金属氧化物TiO2-MoO3的制备,用TEM、XRD、IR等技术TiO2-MoO3催化剂进行了表征。结果表明纳米TiO2-MoO3催化剂为锐钛矿型晶相,且TiO2-MoO3的紫外吸收比纯TiO2的紫外吸收强度大得多。研究了催化剂TiO2-MoO3对甲基红的紫外光催化降解。探讨了MoO3的掺杂比例,催化剂用量及不同时间对甲基红的紫外光催化脱色的影响。结果表明,在适宜的反应条件下,脱色率达89．264％。     

Polybutylacrylate/poly(methyl methacrylate) Core-Shell Elastic Particles as Epoxy Resin Toughener:Part Ⅰ Design and Preparation

Polybutylacrylate (PBA)/poly(methyl methacrylate) (PM MA) core-shell elastic particles (CSEP), whose rubbery core diameterranged from 0.08 μm to 1.38 μm, were synthesized by using conventional emulsion polymerization, multi-step emulsion polymerization, and soapless polymerization. Allyl methacylate (ALMA) and ethylene glycol dimethacrylate (EGDMA) were selected as crosslinking reagents for core polymerization. Methacrylic acid (MAA) was used as functional co-monomer with methyl methacrylate as shell component. The content of vinyl groups in PBA rubbery core increased with the amount of crosslinking reagents. The core-shell ratio affected great on the morphology of the complex particles. Furthermore, the amounts of carboxyl on the surface of core-shell particles, copolymerized with acrylic acid, were determined by potentiometric titration. Results showed that methylacrylic acid was distributed mostly on the surface of particles.     

共聚物水凝胶温度及pH敏感行为的研究

用自由基聚合法合成了NVP／HEMA和NVP／HEMA／AAm共聚物水凝胶材料,研究了温度、pH值、离子强度等因素对凝胶溶胀性能的影响。结果表明水凝胶的溶胀度随着温度的升高而减少;水凝胶在酸性溶液中溶胀,在碱性溶液中收缩,显现出良好的pH值敏感性;水凝胶的溶胀度随着离子强度的增加而减少。     

空心钛硅分子筛在二甲基硫醚液相氧化反应中的催化性能

在以过氧化氢为氧化剂的二甲基硫醚液相氧化反应体系中,对空心钛硅分子筛（HTS）的催化性能进行了系统研究,详细考察了催化剂存在与否以及催化剂用量、反应时间、反应物料配比及溶剂用量等不同反应条件变化对二甲基硫醚温和液相氧化反应的影响。研究发现,在温和反应条件下,HTS催化二甲基硫醚氧化反应中主要产物是二甲基亚砜和二甲基砜。经优化后,能够获得较好的氧化二甲基硫醚制备二甲基亚砜的反应效果,在二甲基硫醚转化率超过99%的情况下,二甲基亚砜选择性可达95%以上。     

The direct,one-step process for synthesis of dimethyl ether from syngas. III. DME as a chemical feedstock

In Parts I & II of this Series, we illustrated the process research studies on a new, trendsetting indirect syngas conversion process, the direct, one-step LPDME^tm process, which is now a shining example of “dual catalysis” or “cooperative/adaptive” catalysis and also of thermodynamic/kinetic coupling in series-parallel reactions.

In this part III, we take a look at several processes on the research and pilot scale that employ methanol and DME as chemical feedstocks for further conversion to value-added chemicals. A most rational and cogent argument for the use of DME as a feedstock is that the unit production cost of DME from the direct, one-step DME processes, most notably the LPDME^tm process, can be lower than methanol (from LPMeOH^tm), on a methanol-equivalent basis. DME also has inherently more benign physical and chemical properties, contains 1 less mole of water, and results in a substantially similar product distribution, as methanol, for the methanol-to-gasoline (MTG) and methanol-to-olefins (MTO) process. DME can also be converted to several other important chemicals; some of these include dimethoxymethane, dimethoxyethane, methylal, formaldehyde, acetic acid, methyl acetate, and polyoxymethylene ethers. In this report, we offer a critical assessment of the current status of these processes and a projected path to commercialization. Considering the trendsetting and impactful nature of DME as a chemical entity and as a chemical feedstock, along with its “free” cost, we are of the opinion that the future of DME, and of its chemical conversions, as so-called “DME economy”, is very bright.     

Synthesize and characterization of new polymeric surfactants based on nonionic maleate surfmer by catalytic bulk copolymerization with methyl methacrylate

Non-ionic maleate surfmer (M1) was prepared via ring opening reaction of maleic anhydride with hexanol followed by esterfaction with polyethylene glycol. The prepared surfmer was homo-polymerized and copolymerized with methyl methacrylate (M2) at different conditions using TiO₂ and V₂O₅ as catalysts in presence of O₂ or N₂. The chemical structure of the prepared surfmer, homo-polymer and copolymer were confirmed by FT-IR, ¹³C and ¹H NMR. The molecular weights of the prepared polymers were measured using Gel Permeation Chromatography (GPC) and their thermal gravimetric analysis (TGA) was determined. TGA indicated a higher thermal stability for the copolymers M1M2TN and M1M2VO relative to the pure polymethylmethacrylate (PMMA). The interfacial tension for the prepared surfmer and the copolymer was measured. The optimum conditions which resulted in 64.2% and 63.8% conversion were 20% w/w TiO₂ in N₂ and 10% w/w V₂O₅ in O₂ at 80?°C for 4?h with M1/M2 molar ratio of 1:1.     

Fatty acid composition, conjugated linoleic acid isomers and cholesterol in beef from crossbred bullocks intensively produced and from Alentejana purebred bullocks reared according to Carnalentejana-PDO specifications

The purpose of this study was to characterise and compare the nutritional value of Portuguese Carnalentejana-PDO beef, obtained from Alentejana purebred bullocks reared in a semi-extensive system, with the meat from Alentejana×Charolais crossbred bullocks produced in a conventional intensive concentrate-based system. In addition, seasonal changes in Carnalentejana-PDO beef quality were assessed, by analysing meat samples from animals slaughtered in early autumn and late spring. The results showed that beef-PDO has different intramuscular fat characteristics in comparison with meat from crossbred bullocks fed intensively with concentrate. However, the finishing period of Alentejana purebred bullocks with concentrate seems to attenuate most of the typical grass-fed characteristics of meat fat. Nevertheless, from a human nutrition perspective, Carnalentejana-PDO beef seems to be healthier than that from intensively reared animals since it has a lower n-6/n-3 ratio, although always above the recommended guidelines for human diet, and higher proportions of c9,t11 conjugated linoleic acid (CLA) isomer and total CLA relative to saturated fatty acids plus total cholesterol (CLA/SFA+CHR). Furthermore, no seasonal variation in the nutritional quality of beef-PDO was apparent. Taken together, the data indicate that Carnalentejana-PDO beef is of greater nutritional value than intensively produced beef from crossbred bullocks throughout the year.     

Unexpected Crosslinking During Acetoacetoxy Group Protection on Waterborne Crosslinkable Latexes

Summary: The microstructure of the polymer synthesized by seeded semicontinuous emulsion copolymerization of AAEMA was investigated. It was found that the neutralization of the latexes with ammonia to protect acetoacetoxy functionality against hydrolysis during storage had a remarkable effect on the gel content. A base catalyzed Michael addition reaction between acetoacetoxy groups and terminal double bond (TDB) is proposed as responsible for the chain precrosslinking observed. The presence of TDB in the latexes was demonstrated by means of ¹H NMR. Moreover, the chain precrosslinking affected the subsequent crosslinking reaction of the latex with diamines hindering chain interdiffusion and yielding poorer mechanical properties.

Michael addition between AcAc functional groups and TDB, and final gel content of the MMA/BA/MAA latexes with different amounts of AAEMA.