Extraction of coals through dilute alkaline hydrolytic treatment at low temperature and ambient pressure

Assam and Talcher (bituminous) coals have been subjected to batch aqueous alkali treatment followed by extraction. It has been shown that alkali treatment increased extractability and reactivity of coal. Use of 1.4% aqueous sodium hydroxide was found to be capable of rendering about 40–50% coal extractable in ethylene diamine in two alkali treatments followed by extractions. Semibatch operation yielded about 26–33% extractable coal, and extraction data were found to be comparable with those obtained in batch degradation via a single alkali treatment. Of the solvents studied, polar and basic solvents were found to be the most effective.     

聚羧酸减水剂的常温合成工艺

目前聚羧酸减水剂的合成工艺主要以加热为主,低温合成工艺报道较少。本文为了解决这一问题,以异戊烯醇聚氧乙烯醚（TPEG）、丙烯酸（AA）为主要聚合单体,研究分析反应温度、保温时间、A/B液滴加时间、酸醚比、引发剂过硫酸铵用量（APS）等因素对合成减水剂产品性能的影响。并利用正交试验,筛选出常温条件下较优的合成工艺：酸醚比n（AA）∶n（TPEG）=3.5∶1,引发剂过硫酸铵用量（按TPEG单体质量分数计）为0.5%,反应温度30℃,A液滴加2.25h,B液滴加3.5h,保温时间1.5h。合成减水剂产品在水灰比0.29,掺量0.25%的条件下,水泥净浆初始流动度达到240mm,1h后净浆流动度损失5mm,相同掺量下与其他减水剂产品相比具有更好的分散性和分散保持性。     

Synthesis and characterization of low density and hydrophobic silica aerogels dried at ambient pressure using sodium silicate precursor

The present paper deals with the synthesis and characterization of low density and hydrophobic silica aerogels dried at ambient pressure using low cost sodium silicate precursor. The hydrogels were prepared by sol–gel processing of sodium silicate precursor and acetic acid catalyzed water followed by vapour passing and solvent exchange with methanol. The mixture of MeOH:trimethylchlorosilane (TMCS):hexane was used for the end capping of the silanols present on the silica surface. The process was optimized by varying vapour passing time, gel ageing time, molar ratios of H₂O/Na₂SiO₃, CH₃COOH/Na₂SiO₃ and TMCS/Na₂SiO₃ and silylation period. The aerogels have been characterized by bulk density, % of volume shrinkage, porosity, Fourier transform infrared spectroscopy, thermogravimetric and differential thermal analysis and contact angle measurements. The best quality silica aerogels in terms of low density (0.073 g/cc), higher porosity (96%) and better hydrophobicity (θ = 146°) have been obtained with the molar ratio of Na₂SiO₃:H₂O:CH₃COOH:TMCS at 1:166.6:2.25:11.9.     

Electrochemical reduction of carbon dioxide in methanol at ambient temperature and pressure

The electrochemical reduction of carbon dioxide was studied in methanol-based supporting electrolytes on various metal electrodes at ambient temperature and pressure. The ionophore of the catholyte was benzalkonium chloride, [RN(CH3)2CH2C6H5]⁺Cl^–, where R=C8–C18, the chain length being distributed around C14. A divided H-type cell was used, the supporting electrolytes were 10–2moldm–3 benzalkonium chloride in double distilled methanol (catholyte) and a 10–1moldm–3 aqueous KHCO3 solution (anolyte). Nine different, high purity (>99.5%) metal electrodes were used: Ti, Fe, Co, Ni, Pt, Ag, Au, Zn and Sn. Carbon monoxide, methane and ethane were the main organic products. Silver, Au, Zn and Sn cathodes allowed for the best faradaic yields of CO production, the maximum amount of CO (71%, 185 mmol) being formed on the Ag electrode. Methane evolved on each of the nine tested electrodes, with current yields in the range from 0.2 to 3.0%. Ethane and ethylene were produced on the nickel electrode, with low faradaic efficiencies, 0.5 and 0.3%, respectively. No dimerization products were detected. This research can contribute to large-scale manufacturing of useful organic products from a readily available and cheap raw material: CO2-saturated methanol from industrial absorbers (the Rectisol process).     

Synthesis of star polymethyl acrylate by SET-LRP at ambient temperature

The star-shaped polymethyl acrylate (PMA) was synthesized by single electron transfer living radical polymerization (SET-LRP) at 30 °C in dimethyl sulfoxide, using 2,2-dibromomethyl-1,3-dibromopropane as the multifunctional initiator, Cu⁰ powder and tris-(2-dimethylamino ethyl)amine (Me₆-TREN) as catalyst. The structure of polymer was analyzed by ¹H NMR, and the results showed that the star-shaped PMA had perfect chain ends (–Br) retention. In addition, the polymerization proceeded smoothly and the time dependence of ln([M]₀/[M]) was linear, which could indicate a first order propagation rate with respect to both radicals and monomer concentration, the polymerization was the living polymerization. The M _n and M _w/M _n of polymer were being measured by Gel Permeation Chromatography. The k _p^app = 0.0367 h⁻¹ and the conversion was 36.3% at 16 h, meanwhile the M _n^GPC of the polymer was 13,300 and the M _w/M _n was 1.40.     

Synthesis of ZSM-5 at low temperature and atmospheric pressure in a pilot-scale batch reactor

The synthesis of ZSM-5 was carried out at 100°C and atmospheric pressure in a 30 l batch reactor. The results show that a quality of ZSM-5 can easily be synthesized with a well-developed framework structure within 72 h of reaction. The crystallinity readily reached almost 100% and the yield was well over 70% for samples having various SiO₂/Al₂O₃ ratios. As the SiO₂/Al₂O₃ ratio decreased, the morphology changed from euhedral to spherulite along with an increase of aggregation. The average BET surface area of the samples was 371 m² g⁻¹ and nuclear magnetic resonance spectroscopic studies showed a quality of ZSM-5 with the least defect sites in the framework structure.     

TGH-3Q型羰基硫常低温水解催化剂及应用

研究了太原理工大学开发的TGH－3Q型COS水解催化剂上的动力学行为。实验表明,这种改进型催化剂在温度40～180℃范围显示很高的催化活性和抗氧中毒能力。该催化剂已成功用于氨厂和甲醇厂的气体净化,使用寿命超过三年。根据用无梯度微型反应器和色谱仪获得的结果,其水解反应的本征速率可表达为：对于大颗粒催化剂,宏观速率可表示为该催化剂的耐毒害能力与其上沉积的硫／硫酸盐沉积学密切相关。在所提出的机理的基础上给出了催化剂因氧毒害而失活的动力学模型。     

室温自交联型丙烯酸酯改性聚氨酯乳液的制备

本文以异佛尔酮二异氰酸酯(IPDI)、聚酯二元醇(Mn=1500)、二羟甲基丙酸(DMPA)、甲基丙烯酸羟乙酯(HEMA)、甲基丙烯酸甲酯(MMA)、双丙酮丙烯酰胺(DAAM)等作为主要原料合成聚丙烯酸酯-聚氨酯乳液(PUA)。考察了MMA、DAAM含量及DAAM/ADH不同比例对PUA的乳液粒径、涂膜耐水性和硬度等的影响。通过红外光谱、激光粒度仪等手段,选取了制备PUA较好的工艺配方,为合成性能优异的聚丙烯酸酯-聚氨酯乳液奠定了的基础。     

High‐temperature esterification of fatty acids with methanol at ambient pressure

The article presents the results of the kinetic study of the acid‐catalyzed esterification of free fatty acids (FFA) with methanol (MeOH) at elevated temperatures above the boiling point of MeOH, at ambient pressure, and at continual flow of liquid MeOH into the reaction mixture. Under these conditions, the reaction follows the rate equation valid for reactions of the first order. Beside temperature, the pseudo rate constant depends also on the flow rate of MeOH and on the concentration of a catalyst. At temperatures 50–60 °C higher than the boiling point of MeOH, the reaction rate is two to three times higher than at the temperatures close to the boiling point of MeOH. Apart from the temperature, the increase of the rate is facilitated also by a high local molar excess of MeOH in the input site with respect to FFA and by effective removal of water from the reaction mixture. The composition of the reaction mixture is then farther from the equilibrium composition. High conversion of FFA to methyl esters (above 99%) with low residual acidity of the product (acid value around 2–3 mg KOH/g) is achieved at short times of several tens of minutes and at a low total molar ratio of MeOH/FFA of around 3–4.     

低温合成苯乙烯-马来酸酐交替共聚物

苯乙烯(St)和马来酸酐(MA)自由基引发共聚反应,生成共聚物SMA,是典型的交替共聚。在过氧化苯甲酰(BPO)引发下,以丙酮为溶剂,采用溶液聚合法合成苯乙烯-马来酸酐共聚物,并用收率作为评价标准,对反应条件进行研究。结果表明,在温度为60℃,BPO的质量分数x(BPO)=0.3%,n(苯乙烯)∶n(马来酸酐)=1∶1,w(单体)=30%,反应2 h的条件下,聚合物的收率可达到98.5%。利用化学滴定法测得聚合物中马来酸酐摩尔分数为49.91%,结合理论,证明了合成的苯乙烯-马来酸酐共聚物是一种交替共聚物。一种低温合成苯乙烯-马来酸酐交替共聚物的工艺得到开发。     

Novel oxidation reaction at ambient temperature and atmospheric pressure with electric discharge and oxide surface

We investigated a novel oxidation reaction with surface-oxygen and lattice-oxygen induced using a non-equilibrium electric discharge at ambient temperature. We employed MgO, ZrO₂, and TiO₂ for this novel reaction. Methane was oxidized easily and converted into H₂, CO, and CO₂ by the surface-oxygen and lattice-oxygen of oxide with activation of discharge at ambient temperature without gas-phase oxygen. The oxide itself was stable after the reaction. Among these oxides, the tetragonal phase and amorphous phase of ZrO₂ showed remarkably high activity for methane oxidation. Consequently, up to 8% of surface and lattice oxygen of the oxide was consumed by methane oxidation induced by electric discharge. The non-equilibrium electric discharge activated both the surface-oxygen and the lattice-oxygen of the oxides and methane molecules in the gas phase. After these reactions, the oxide surface vacant sites were recovered partially through steam post-treatment. Hydrogen formed simultaneously with steam decomposition. Other reactions were also studied by changing the reaction gas: methane into carbon monoxide, carbon monoxide with oxygen, and carbon monoxide with steam. Furthermore, the correlation of reactivity between the feed gas and surface oxygen was studied. Emission spectra under a CH₄ atmosphere with electric discharge showed complex peaks caused by carbon monoxide formation at 280-500 nm at 0-4 min, suggesting that surface oxygen on oxides was probably consumed within 4 min from the start of the reaction.     

Synthesis of graphene on silicon carbide substrates at low temperature

A method for the synthesis of millimeter-scaled graphene films on silicon carbide substrates at low temperatures (750 °C) is presented herein. Ni thin films were coated on a silicon carbide substrate and used to extract the substrate’s carbon atoms under rapid heating. During the cooling stage, the carbon atoms precipitated on the free surface of the Ni and formed single-layer or few-layer graphene. The result shows that the number of graphene layers might be further controlled by appropriate process conditions. In contrast to the epitaxial graphene synthesis on single crystal silicon carbide, the graphene prepared here are continuous over the entire Ni-coated area, and can be stripped from the substrate much more easily for further characterization. The large-scaled, low temperature and transferable features of our method suggest the potential for future graphene-based applications.     

Selective hydrogen purification through graphdiyne under ambient temperature and pressure

Graphdiyne, a recently synthesized one-atom-thick carbon allotrope, is atomistically porous - characterized by a regular "nanomesh"- and suggests application as a separation membrane for hydrogen purification. Here we report a full atomistic reactive molecular dynamics investigation to determine the selective diffusion properties of hydrogen (H(2)) amongst carbon monoxide (CO) and methane (CH(4)), a mixture otherwise known as syngas, a product of the gasification of renewable biomass (such as animal wastes). Under constant temperature simulations, we find the mass flux of hydrogen molecules through a graphdiyne membrane to be on the order of 7 to 10 g cm(-2) s(-1) (between 300 K and 500 K), with carbon monoxide and methane remaining isolated. Using a simple Arrhenius relation, we determine the energy required for permeation on the order of 0.11 ± 0.03 eV for single H(2) molecules. We find that addition of marginal applied force (approximately 1 to 2 pN per molecule, representing a controlled pressure gradient, ΔP, on the order of 100 to 500 kPa) can successfully enhance the separation of hydrogen gas. Addition of larger driving forces (50 to 100 pN per molecule) is required to selectively filter carbon monoxide or methane, suggesting that, under near-atmospheric conditions, only hydrogen gas will pass such a membrane. Graphdiyne provides a unique, chemically inert and mechanically stable platform facilitating selective gas separation at nominal pressures using a homogeneous material system, without a need for chemical functionalization or the explicit introduction of molecular pores.     

常温固化聚氨酯介电灌封胶

合成了常温固化聚氨酯介电灌封胶,杀考察了多元醇用量、异氰酸酯基含量、增塑剂用量、阻燃剂用量对其性能的影响。结果表明,三元醇用量为聚醚多元醇的20%～40%,异氰酸酯基质量分数为2.3%～3.0%,增塑剂和阻燃剂等添加剂占反应物总量的40%～60%时得到的灌封胶性能较好。     

低含量PcBN复合片在高温高压下的合成

通过不同铝含量(10vol%,15vol%,20vol%,25vol% 30vol%)在Al-TiN-cBN体系下高温高压合成低含量PcBN复合片并研究其性能.通过XRD发现生成了TiB2、AlN、Al2O3三种物相,随着铝含量的增多,新生相AlN、Al2O3的含量逐渐增多.通过硬度检测和弯曲试验发现:由于AlN和Al2O3相的增多,相对降低了cBN的含量,显微硬度值也随着铝含量的增多而逐渐降低;而由于铝的催化效果,随着铝含量的增多(10vol%～20vol%),强的cBN-cBN键就逐渐增多,增强了其韧性,再增加铝的含量(25vol%～30vol%))韧性反而降低.切削试验发现,铝含量为20vol%时候,切削效果最佳.这是PcBN复合片显微硬度和抗弯强度的一种综合体现.     

Investigation of passive DMFC mini-stacks at ambient temperature

Two designs of flow fields/current collectors for a passive direct methanol fuel cell (DMFC) monopolar three-cell stack were investigated. The first one (A) consisted of two plastic plates covered by thin gold film current collectors in the area of electrodes with a distribution of holes through which methanol (from a reservoir) and air (from ambient) could diffuse into the electrodes. The second design (B) consisted of thin gold film deposited on the external borders of the fuel and oxidant apertures where the electrodes were placed in contact. A big central hole allowed a direct exposure of electrodes to ambient air (for the cathodes) and methanol solution (for the anodes). An investigation of the performance and discharge behaviour of the two designs was carried out. The advantages and disadvantages of each configuration were analysed. Similar performances in terms of maximum power were recorded; whereas, better mass transport characteristics were obtained with the design B. On the contrary, open circuit voltage (OCV) and stack voltage at low current were higher for the design A as a consequence of lower methanol cross-over. A longer discharge time (17 h) with a unique MeOH charge was recorded with design B at 250 mA compared to the design A (5 h). This was attributed to an easier CO₂ removal from the anode and better mass transport properties.     

常压制备疏水性二氧化硅气凝胶

以正硅酸乙酯(TEOS)为硅源,氢氟酸作催化剂,采用溶胶-凝胶法常压下制备二氧化硅气凝胶,并研究催化剂、乙醇、水等因素对凝胶过程的影响。采用傅里叶变换红外分析(FT-IR)、电子扫描探针(SPM)等对二氧化硅气凝胶的结构和性能进行研究。结果表明,经三甲基氯硅烷(TMCS)表面改性处理后的气凝胶表现出了很好的疏水性能。该气凝胶密度为200~400 kg/m³,与水的接触角大于120°。当n(TEOS)∶n(乙醇)∶n(H₂O)∶n(HF)=1∶6∶4∶0.25时,得到的气凝胶各方面的综合性能最好。凝胶时间随着水和氢氟酸用量增加而缩短,随乙醇用量的增加而增加。     

Dual-curing of anionic aqueous-based polyurethanes at ambient temperature

Polyurethane (PU) prepolymers are prepared by a polyaddition of isophorone diisocyanate, polypropylene glycol-1000, and 2,2-dimethylolpropanic acid. The anionic aqueous-based PU dispersions are derived from a water dispersion process of these NCO-terminated PU prepolymers together with a neutralization and a chain extension. They have both terminal amino and pendent carboxylic groups which are potentially reactive sites toward a di-functional epoxy and a tri- or di-aziridinyl compound of a dual-curing PU system, respectively. The stabilities of the resulting PU dispersions on zeta potential and particle size distributions are investigated. The improvements on mechanical, physical, and thermal properties of these dual-cured PU systems are also evaluated. © 1998 John Wiley & Sons, Inc. J Appl Polym Sci 67:1661–1671, 1998