Catalyst development for the selective oxidation of ethoxylates to their corresponding ether carboxylic acids

The aerobic selective oxidation of polyethoxylates to their corresponding carboxylic acids was investigated using supported Au-based catalysts in aqueous alkaline solution. Introduction of Pt as secondary metal to the titania supported Au catalyst led to a significant boost in activity while maintaining total selectivity. A screening of different preparation methods and metal ratios led to a titania supported AuPt catalyst with a substantially reduced intermediate leaching of the catalytically active metals. A long-term stability study showed no noble metal loss of this particular catalyst after a set of repeated batches, but still revealed a distinct loss in activity due sintering of the metal nanoparticles. By switching from titania to ceria as support material, intermediate metal leaching could be prevented completely while maintaining total selectivity and further enhancing the activity.     

Experimental study of the influence of sodium salts as additive to NO<Subscript><Emphasis Type="Italic">x</Emphasis></Subscript>OUT process

An experimental study of the SNCR process with urea as reducing agent and sodium salts as additive has been carried out, and detailed analysis of the reaction mechanism has been given here. In the temperature range of 800–975 °C, NO concentration decreases at first and then increases while the concentration of N₂O increases at first and then decreases with the increasing of temperature, and the turning point is 900 °C. With increasing of normalized stoichiometric ratio of reduction nitrogen to NO _x (NSR), NO removal efficiency increases, while the concentration of N₂O also increases, which decreases overall NO _x removal efficiency. With sodium salts as additive, the concentration of N₂O decreases with increasing of sodium salts addition at all temperatures, while the concentration of NO decreases at first and then increases at low-temperature side of the temperature window and increases at high-temperature side with additional increasing, whose changing extent is smaller than N₂O. Since sodium salts as additive can remove N₂O effectively and have no large influence on the removal of NO, the effect of sodium salts as additive is the combined effect of the production of active radicals and the removal of HNCO produced by the decomposition of urea through neutralization reactions, which is more important. To achieve the same effect under each condition, the needed addition of NaOH and CH₃COONa is less than that of Na₂CO₃ counting as Na atom. For the decomposition of CH₃COONa can produce CH₃COO, its addition can promote the reduction of NO more obviously at the lower temperature than Na₂CO₃ or NaOH. Overall NO _x removal efficiency at 900 ‡C with NSR=1.5 had been improved from about 30% to 70.45% through the addition of sodium salts. Sodium salts as additive caused the flue gas to become alkaline gas, but it was not serious for sodium salts existing as NaNCO.     

Synthesis and characterization of zirconia-based catalyst for the isomerization of n-hexane

Sulfated zirconia is a very strong solid acid catalyst which can be utilized for various reactions. The present study focuses on synthesis of zirconia-based catalyst with high acidity and high surface area, particularly for isomerization reaction. Sulfated zirconia has been obtained by sulfation of zirconia prepared by hydrothermal route. The catalyst was developed by impregnating tungstophosphoric acid on sulfated zirconia by wet incipient method. The catalyst was characterized through Brunauer–Emmett–Teller (BET) surface area, temperature-programmed desorption of ammonia, temperature program reduction of hydrogen, Fourier transmission infrared spectroscopy, and thermogravimetric analysis. The results revealed that the catalyst is crystalline in nature with surface area 190–225?m² g^?1 and acidity 0.135–0.558?mmol?g^?1. Twenty-five percent conversion was obtained (as confirmed by gas chromatography) at 225°C using n-hexane as model hydrocarbon in fixed-bed microreactor.     

High speed microcompression of paper coatings

A novel high speed microcompression platen tester was developed in order to measure the out-of-plane compressive modulus of thin materials. The instrument is capable of subjecting a sample of thickness 20 μm or greater to a transverse compressive pulse over a time interval ranging from approximately 2 ms to several seconds, and can therefore be used to collect data under conditions representative of those in a high speed calender nip. In this study, free layers of coating formulations normally used to coat paper were prepared and tested using the microcompression platen tester described above. Tests were conducted at high speeds, with a pulse duration of 2 ms during the compressive stroke, and at 23 °C to simulate room temperature calendering conditions. The compressive modulus of the coating did not correlate strongly with the modulus of its constituent latex. Latex content, however, strongly affected coating compressive modulus. A sharp increase in the compressive modulus was observed at the coating critical pigment volume concentration (CPVC)—essentially the latex concentration at which the coating layer porosity is reduced to zero. Pigment size distribution and pigment morphology also affected the compressive modulus of coating in a manner consistent with packing theory.     

Fouling tendency of ash resulting from burning mixtures of biofuels. Part 1: Deposition rates

Specified mixtures of peat with bark and peat with straw were burned in a lab-scale entrained flow reactor that simulates conditions in the superheater region of a conventional biomass-fired boiler. The deposition rates were recorded on an air-cooled probe that was inserted into the reactor at the outlet. For both mixtures, the deposition behaviour followed a non-linear pattern, which suggests that physico-chemical interaction between the types of ash has taken place. Peat seems to act as a cleansing agent in all mixtures with straw, while it acts as a cleansing agent in mixtures with bark only up to a share of 50 wt% bark. Between 50 and 100 wt% bark, it seems that peat adds to the deposition. The results indicate that it is possible to burn up to 30 wt% bark (renewable biofuel and pulp mill waste) and up to 70 wt% straw (renewable biofuel and agricultural waste) in mixtures with peat (CO₂-neutral fossil fuel) without encountering increased deposition rates.     

Mn^2＋-TiO2介孔复合材料的制备及其光催化降解对氯苯酚

以钛酸四丁酯为前驱体，三嵌段共聚物为模板剂，通过sol—gel工艺成功合成了掺杂Mn^2＋离子的介孔TiO2复合材料，并利用小角X-射线衍射（LAXRD）、广角X-射线衍射（XRD）及透射电镜分析（TEM）对样品进行了表征。结果表明，Mn^2＋离子的掺杂能够阻止TiO2的相转变，提高TiO2介孔结构的热稳定性。在通氧、紫外光连续照射条件下，使用掺杂Mn2％的Mn^2＋-TiO2作催化剂对初始浓度为60mg／L的对氯苯酚进行催化降解，3h后降解率达到81．7％。     

Pulped Phormium tenax leaf fibres as reinforcement for epoxy composites

Leaf fibres from Phormium tenax (harakeke, New Zealand flax) were pulped at 170 °C with NaOH and anthraquinone. The pulp was wet laid to form mats, which were used to reinforce epoxy composites. The flexural modulus was almost as high as that measured for epoxy reinforced with glass chopped strand mat at the same weight fraction. The flexural strength was two-thirds that of the glass-reinforced composite. Failure was abrupt. SEM images showed torn fragments of fibre cell walls protruding from the fracture surface, indicating strong interfacial bonding. Good mechanical performance was attributed to the rarity of kink bands in the individual fibre cells, along with wrinkled cell-wall surfaces that enhanced the area of the fibre–matrix interface.     

基于MATHEMATICA的因次分析程序

因次分析是一种重要的数学建模方法,广泛应用于化工原理中与湍流有关的物理现象的无因次数群关联式的建立。经典化工原理在因次分析过程中采用手算法进行符号运算,非常烦琐；本文基于MATHEMATICA软件强大的符号运算功能,给出了一个因次分析程序,用来进行因次分析中的这些烦琐而重复的计算。本文还给出了该程序的若干应用实例。     

Green antimicrobial coating based on quaternised chitosan/organic montmorillonite/Ag NPs nanocomposites

This work is aimed at developing a green antimicrobial coating. First, a green antimicrobial agent, quaternised chitosan (QCS)/organic montmorillonite (OMMT)/silver nanoparticles (Ag NPs) (QOMA) nanocomposite was fabricated through an environmental-friendly one-step approach. Morphological and structural characteristics of QOMA were investigated, and good antimicrobial activity was proved. QOMA was then incorporated into powder coating formulations to form a homogeneous coating on steel plates, which was studied by scanning electron images. Besides, the physical and mechanical properties as well as the antimicrobial performances of the coatings were discussed. The results showed that the addition of QOMA imparted good antimicrobial capacity to the powder coating, but did not affect its physical and mechanical properties. The coatings were able to effectively inactivate Gram-negative bacteria (Escherichia coli), Gram-positive bacteria (Staphylococcus aureus) and fungi (Aspergillus niger, Penicillium funiculosum, Chaetomium globasum, Paecilomyces varioti, Asp. terreus and Aureobasidium pullulans). Our findings demonstrate the possibilities of green antimicrobial coating containing QOMA for practical applications in medical devices, domestic appliances and other solid surfaces concerning bacterial infection and contamination.     

Predictive optimal control for thermo-mechanical pulping processes with multi-stage low consistency refining

In this paper, we present a nonlinear model based dynamic optimization approach for optimal control for thermo-mechanical pulping (TMP) processes. The method is based on nonlinear model predictive control (NMPC) technique with an economic objective function. In our previous work [1], an economically oriented NMPC (econNMPC) was presented for a two-stage TMP process with high consistency (HC) refiners. The two-stage TMP process was simulated up to the secondary refiner. In this study, we extend the previous study to multiple stages that include low consistency (LC) refining. Here we can exploit the complexity of interactions of multiple stage TMP for both performance and optimal operations. The first process is a conventional refining process with two stages of HC refining with a primary and a secondary refiner, followed by a latency chest and a third-stage LC refiner. The second TMP process has only a HC primary refiner, and the secondary stage HC refiner is replaced by multiple stages of LC refiners after the latency chest. Both TMP schemes are dynamically optimized against disturbances to produce the same target final pulp qualities while minimizing specific energy consumption of the processes. The simulation results show the potential economic benefits of the proposed method, through a reduction in total specific energy, about 24%, for the second TMP process.