Superabsorbent polymers (SAPs) can absorb a large amount of water and find broad applications in various industries. There are many reports on the synthesis and structural modification techniques to improve the water absorption property of SAPs. However, we see few studies on the comparison and integration of these techniques. In this study, three structurally modified SAPs were synthesized and are evaluated for the effects of surface cross-linking, foaming, and the integration of the two modifications to improve the absorption rate and capacity of a conventional SAP. First, sodium polyacrylate-polyacrylamide was prepared as the base polymer by the aqueous solution polymerization method. Second, the base polymer was modified with surface cross-linking to enhance absorption, and a surface cross-linked SAP was obtained. Third, the base polymer was modified with foaming to obtain a foamed SAP. Lastly, the foamed SAP was modified further with surface cross-linking to obtain a foamed and surface cross-linked SAP. In comparison with the base polymer, the three synthesized SAPs were evaluated for their absorption performance. Results show that their absorption performance could be improved by the three modification processes. Specifically, the surface cross-linked SAP had the best absorption capacity under load, the foamed SAP had the highest absorption capacity of 1954 g/g, and the foamed and surface cross-linked SAP had the fastest absorption rate with an initial swelling rate of K-is = 21.94.

The present work reports on the promoting effects of rare earth elements (La, Ce and Y) to FeK/Al2O3 catalysts on liquid hydrocarbons from CO2 hydrogenation. The addition of La, Ce and Y can both improve the selectivity of C5+ hydrocarbons and reduce the selectivity of CH4. The C5+ selectivity can enhance to about 60 % with CH4 selectivity of around 11 % at CO2 conversions above 20 %. N-2 adsorption-desorption, in situ XRD, H-2-TPR, CO2/H-2-TPD, HRTEM and XPS are used to characterize the FeK/Al2O3 and FeK/M-Al2O3 (M = La, Ce, Y) catalysts. The results show that the introduction of rare earth elements into the FeK/Al2O3 catalyst obviously reduces the adsorption of H-2, which suppresses the CH4 formation. On the other hand, rare earth elements also promote the adsorbed CO2 species, which leads to the enhanced liquid hydrocarbons selectivity. Finally, the tailored CO2/H-2 ratio of CO2 and H-2 adsorption on the catalyst surface can influence the catalyst activity and the product selectivity evidently.

A novel capillary microphotoreactor (MPR) packed with TiO2-coated glass beads was developed in this work and its photocatalytic performance was evaluated using degradation of methylene blue (MB) as a model reaction. As compared to conventional wall-coated MPR, the use of glass beads as packing material not only provides a larger surface area for catalyst immobilization and shortens the mass transfer route, but also introduces flow perturbation. An appropriate size of glass beads should be chosen for packing because there is a tradeoff between increased catalysts coating area and decreased light penetration. It was found out that nearly 100 % degradation efficiency could be achieved in 80# glass beads packed MPR within short residence time (20 s), which was more than 2 orders of magnitude larger than value obtained in wall-coated MPR under the same operational conditions. Moreover, the packed MPR showed good durability, which declined by about 17 % after 6 h of operation and then remained stable for next 19.5 h.

CuO/MCM-41 catalyst was synthesized by a simple method with the modification of ethylene glycol (EG) and characterized by powder X-ray diffraction (XRD), nitrogen sorption, scanning electron microscopy (SEM) and transmission electron microscope (SEM). Its catalytic performance in the hydrogenation of CO₂ to methanol was also investigated. The results indicated that the as-synthesized CuO/MCM-41-EG catalyst took the properties of high dispersion, small particle size and high surface area, and then showed catalytic performance for the CO₂ hydrogenation to methanol. At the optimum reaction temperature of 240 °C, the CuO/MCM-41-EG catalyst gave 15% CO₂ conversion and 35% methanol selectivity.

采用熔融共混和吹塑成型工艺制备了无孔型热塑性聚氨酯弹性体(TPU)薄膜.以膜厚度、温度和相对湿度为变量对TPU薄膜的透湿和透气性能进行测试分析,并对其表面形貌、成分含量、热稳定性进行了表征.实验结果表明:TPU薄膜的透湿量随着膜厚度的增加而减小,薄膜透湿量随着温湿度的升高而显著增加;按ASTME96BW—2000标准测试,厚度为0.012mm的TPU薄膜透湿量达7093g/(m2·d).利用扫描电子显微镜观察到TPU薄膜表面相对平整,未发现微孔结构.气体渗透率测试分析表明,CH4和N2基本无法透过TPU薄膜,因此TPU薄膜可以有效地阻隔细菌与病毒入侵.傅里叶变换红外光谱表征结果显示,1000～1300cm-1处出现Si—O伸缩振动吸收峰,证明纳米SiO2成功掺杂到TPU中.

AbstractFractal theory, with its novel architectures inspired by nature, provides some novel concepts for smart reactor design. Here, researches on the applications of fractal theory to micro-reactor design are reviewed, in term of its high surface area-to-volume ratio, rapid and direct numbering-up, safety, and precise control. In addition, two designs of fractal micro-reactor are introduced as typical examples. First, the H-type fractal structure is considered in the context of the design of a double-plate micro-reactor, which is used for photocatalytic reactions of CO2. Second, applications of fractal Hilbert curves are considered in the design of channel structures for gas-liquid reactions. These two fractal micro-reactors can be fabricated via 3D printing technology and used for CO2conversion under mild conditions.

Cu/ZnO/MCM-41 catalyst was prepared via a double-solvent impregnation method, and its catalytic performance of CO2 hydrogenation to methanol was investi-gated. The water-ethylene glycol double solvent formed by adding an appropriate amount of ethylene glycol to the metal nitrate aqueous solution in the impregnation process pro-moted metal ions into the channels of MCM-41 support, resulting in the formation of metal particles with very small size. Metal particles were uniformly embedded in MCM-41 chan-nels. The relatively low reduction temperature indicated highly dispersed active sites with strong interaction between Cu and ZnO. Cu/ZnO/MCM-41 catalysts prepared with the method had stable catalytic performance in hydrogenation of CO2 to methanol. By ad-justing loading to control the particle size of Cu, the methanol selectivity and yield could reach 64.3% and 32.8 g·(kgcat)?1·h?1. Therefore the double-solvent impregnation method can effectively limit migration and sintering of active components with optimized particle size, so as to obtain catalysts with highly dispersed active sites and stable catalytic perfor-mance.

The present study investigates CO2-monoethanolamine (MEA) absorption reaction in a novel honeycomb fractal reactor under the laminar flow, with particular reference to the conventional serpentine tubular reactor. The results show the CO2 removal efficiency and absorption rate increase with the increasing liquid flow rate, as well as the increasing MEA when the other conditions remain unchanged. In general, the CO2 removal efficiency and absorption rate in honeycomb fractal reactor are higher than those in serpentine tubular reactor. The honeycomb-shaped configuration provides reaction space with larger surface-to-volume ratio. The fluid from the upper level channel split at the bifurcation when flowing towards the next level of hexagonal unit, leading to a declined reactant velocity in the latter branches and hence increasing the residence time. Besides, in the honeycomb fractal reactor, the flow pattern is maintained as slug flow in which the contact time and area are intensified, leading to the strengthened interface mass transfer. The maximum CO2 removal efficiency of 168% was obtained in honeycomb fractal reactor.

The liquefaction of wheat straws in sub-critical water to obtain bio-oil was investigated in this paper. We observed that the reaction temperature (300-374 °C) and reaction time (1-15 min) played important roles in the yield of bio-oil and found the optimal reaction conditions (340 °C, 5 min). The bio-oil was analyzed by elemental analysis, the Fourier transform infrared spectroscopy (FTIR) and gas chromatography-mass spectrometry (GC-MS). Results indicated that the heating value of bio-oil product was 32-38 MJ/kg, higher than that of the bio-oil obtained from microalgae, and the product was composed of ketones, phenol and its derivatives, aromatics and small amount of aldehydes and ethers.

The electrochemical oxidation of chlorimuron-ethyl on Ti/SnO2-Sb2O5/PbO2 electrode was studied by cyclic voltammetry. The electrochemical behaviour of the electrode in a sodium sulfate solution and in the mixture solution of sodium sulfate and chlorimuron-ethyl was studied. The experimental results of cyclic voltammetry show that the acidic medium was suitable for the efficient electrochemical oxidation of chlorimuron-ethyl. Some electro-generated reagent was formed in the electrolysis process and chlorimuron-ethyl could be oxidized by the electro-generated reagent. A Ti/SnO2-Sb2O5/PbO2 electrode was used as the anode and the electrolysis experiment was carried out under the optimized conditions. The electrolysis process was monitored by UV-Vis spectrometry and high performance liquid chromatography(HPLC), and the chemical oxygen demand(COD) was determined by the potassium dichromate method. The mechanism of chlorimuron-ethyl to be oxided was studied primarily by the cyclic voltammetry and UV-Vis spectrometry. The results of electrolysis experiment demonstrate the possibility of the electrode to be used as an anode for the electrochemical treatment of chlorimuron-ethyl contained in waste water.

In order to find out the simplified and efficient treating method for chlorimuron-ethyl containing waste water, the influence of mass transfer on the degradation process of chlorimuron-ethyl by Ti/SnO2-Sb2O3/PbO2 anode electrochemical oxidation was investigated with cyclic voltammetry and constant current electrolysis method. And the factors influencing the mass transfer and chlorimuron-ethyl degradation reaction were optimized. The electrochemical oxidation mechanism of chlorimuron-ethyl on the Ti/SnO2-Sb2O3/PbO2 anode was primarily studied with cyclic voltammetry and UV-visible spectrometry. The concentration of chlorimuron-ethyl in the electrolysis process was monitored by high performance liquid chromatography (HPLC). The removal effect of chemical oxygen demand (COD) was evaluated with potassium dichromate method. The experimental results show that the nature of waste water, operating condition of electrolysis and mass transfer condition of waste water have the evident influence on the electrochemical degradation of chlorimuron-ethyl on the Ti/SnO2-Sb2O3/PbO2 anode. It is proved that the Ti/SnO2-Sb2O3/PbO2 anode electrochemical oxidation can be used for treating chlorimuron-ethyl containing waste water.

The sulfidation process of porous zinc oxide sorbent with hydrogen sulfide can be described in five steps after external mass transfer and pore diffusion. They are surface adsorption of hydrogen sulfide gas on zinc oxide sorbent and dissociation of the gas molecule on the sorbent surface, followed by reversible surface reactions, sulfide ion migration under the surface, and sulfidation penetration into the solid crystallite. On the basis of the understanding of this chemistry, an empirical rate law for the intrinsic kinetics of the sulfidation process was derived in this study. Kinetics modeling results using this reversible, adsorption, and ion-migration (RAIM) model were found, consistent with selected experiments of single-particle sulfidation. Modeling results were also comparable with several well-defined sulfidation models in the literature. The intrinsic kinetics of a porous ZnO sorbent G-72E were measured in a microflow packed column and calculated using the RAIM model, using a finite difference approach. The effective pore diffusivity of gaseous hydrogen sulfide in the porous zinc oxide pellet was calculated using the general process modeling system (gPROMS). Finally, design calculation for a full-scale packed desulfurizer was performed using the gPROMS distributed reactor model. Case studies were presented for hydrogen sulfide removal from natural gas in a simulated fuel-processing train for syngas production.

After external mass transfer and pore diffusion, sulfidation of porous zinc oxide sorbent with hydrogen sulfide can be described in five steps. They are surface adsorption of hydrogen sulfide gas on zinc oxide sorbent and dissociation of the gas molecule on the sorbent surface, followed by reversible surface reactions, sulfide ion migration under the surface, and sulfidation penetration into the solid crystallite. Based on this understanding of chemistry, an empirical rate law for the intrinsic kinetics of sulfidation process was derived in this study. Kinetics modeling results using this reversible, adsorption, and ion migration (RAIM) model were applied to select experiments of single particle sulfidation and compared with several well-defined sulfidation models from the literature. In modeling the sulfidation with zinc oxide pellets, the saturated sulfur capacity and effective pore diffusivity of gaseous hydrogen sulfide in pellets were calculated using the gPROMS (general PROcess Modelling System) modeling. In modeling the sulfidation in full-scale packed desulfurizers, the gPROMS distributed reactor model was used. Case studies were presented for hydrogen sulfide removal from natural gas in a simulated fuel processing train. Finally, a new understanding on the sulfidation equilibrium in packed bed was proposed.

Based on the water gas shift (WGS) catalytic mechanism on precious metal catalyst, a Langmuir–Hinshelwood (LH) kinetics model was derived for the operating conditions of syngas from natural gas reforming at near-ambient pressure. A power law kinetics model was also presented for comparative purpose. These two kinetics models were integrated in a dynamic distributed reactor model for design of full-scale WGS reactors for a natural gas fuel processing system. Modeling results indicated that the LH kinetics model gives predictions of reactor performance closer to the experimental data. Using the LH kinetics model, optimization of operating conditions for the high-temperature shift (HTS) and low-temperature shift (LTS) reactors was also attempted.

There is a potential for using waste tire rubber to make activated-carbon adsorbents for air-quality control applications. Such an approach provides a recycling path for waste tires and the production of new adsorbents from a low-cost waste material. Tire-derived activated carbons (TDACs) were prepared from waste tires. The resulting products are generally mesoporous, with N-2-BET specific surface areas ranging from 239 to 1031 m(2)/g. TDACs were tested for their ability to store natural gas and remove organic compounds and mercury species from gas streams. TDACs are able to achieve 36% of the recommended adsorbed natural gas (methane) storage capacity for natural-gas-fueled vehicles. Equilibrium adsorption capacities for CH4 achieved by TDACs are comparable to Calgon BPL, a commercially available activated-carbon adsorbent. The acetone adsorption capacity for a TDAC is 67% of the adsorption capacity achieved by BPL at 1 vol % acetone. Adsorption capacities of mercury in simulated flue-gas streams are, in general, larger than adsorption capacities achieved by coal-derived activated carbons(CDACs) and BPL. Although TDACs may not perform as well as commercial adsorbents in some air pollution control applications, the potential lower cost of TDACS should be considered when evaluating economics.

Despite technical advances to reduce air pollution emissions, motor vehicles still account for 30 to 70% emissions of all urban air pollutants. The Clean Air Act Amendments of 1990 require 100 cities in the United States to reduce the amount of their smog within 5 to 15 years. Hence, auto emissions, the major cause of smog, must be reduced 30 to 60% by 1998. Natural gas con be combusted with less pollutant emissions. Adsorbed natural gas (ANG) uses adsorbents and operates with a low storage pressure which results in lower capital costs and maintenance. This paper describes the production of an activated carbon adsorbent produced from an Illinois coal for ANG.

Granular activated carbons (−20 + 100 mesh; 0.149−0.84 mm) were produced by physical activation and chemical activation with KOH from an Illinois bituminous coal (IBC-106) for natural gas storage. The products were characterized by BET surface area, micropore volume, bulk density, and methane adsorption capacities. Volumetric methane adsorption capacities (VmVs) of some of the granular carbons produced by physical activation are about 70 cm3/cm3 which is comparable to that of BPL, a commercial activated carbon. (VmVs) values above 100 cm3/cm3 are obtainable by grinding the granular products to −325 mesh (<0.044 mm). The increase in (VmVs) is due to the increase in bulk density of the carbons. Volumetric methane adsorption capacity increases with increasing pore surface area and micropore volume when normalizing with respect to sample bulk volume. Compared with steam-activated carbons, granular carbons produced by KOH activation have higher micropore volume and higher methane adsorption capacities (g/g). Their volumetric methane adsorption capacities are lower due to their lower bulk densities.