蓄能地板辐射采暖系统热性能的研究

利用相变传热理论，建立起分析热盘管置于封装相变储能材料层中的储能采暖地板热性能的理论模型，采用焓分析法，数值模拟贮热介质在曲边边界条件下、不同的热边界条件的作用，探索蓄能地板在不同的管间距布置、不同的地板覆盖层和不同供热工况等各种因素对储能地板热性能及蓄热效果的影响规律。     

不同季铵盐作用下的CO2水合物相平衡

CO₂气体水合物形成热力学性质是实施海水淡化、沼气纯化、碳捕集和封存、能源利用、天然气储存等技术的关键。采用恒容温度搜索法,在温度272.75~294.35 K,压力0.35~4.50 MPa的范围内,探究了四种季铵盐促进剂对CO₂气体水合物相平衡的影响。结果表明,相同条件下,季铵盐作用下CO₂水合物的相平衡温度由高到低分别为：四丁基氟化铵（TBAF）>四丁基溴化铵（TBAB）>四丁基氯化铵（TBAC）>苄基三乙基氯化铵（TEBAC）。基于Clausius-Clapeyron方程,计算了不同体系的相变潜热,探讨了其对水合物稳定性的影响。可以看出,水合物的相平衡压力对数与温度倒数呈线性关系,其中,TBAF、TBAB作用下的CO₂水合物相变潜热相接近且明显高于其他季铵盐,说明其促进效果最好,所对应的水合物生成条件也最为温和。利用Chen-Guo模型,结合PR状态方程和改进Joshi经验活度模型,分别计算了TBAF、TBAB、TBAC和TEBAC作用下CO₂水合物热力学相平衡数据,计算结果与实验数据吻合良好,最大平均相对误差为7.50%。     

Computer generation of detailed reaction networks in hydrocracking of Fischer-Tropsch wax

Fischer-Tropsch synthesis (FTS) wax is a mixture of linear hydrocarbons with carbon number from C7 to C70+.Converting FTS wax into high-quality diesel (no sulfur and nitrogen contents) by hydrocracking technology is attractive in economy and practicability.Kinetic study of the hydrocracking of FTS wax in elementary step level is very challenging because of the huge amounts of reactions and species involved.Generation of reaction networks for hydrocracking of FTS wax in which the chain length goes up to C70 is described on the basis of Boolean adjacency matrixes.Each of the species (including paraffins,olefins and carbenium ions) involved in the elementary steps is represented digitally by using a(N + 3) × N matrix,in which a group of standardized numbering rules are designed to guarantee the unique identity of the species.Subsequently,the elementary steps are expressed by computer-aided matrix transformations in terms of proposed reaction rules.Dynamic memory allocation is used in spe-cies storage and a characteristic vector with nine elements is designed to store the key information of a(N + 3) × N matrix,which obviously reduces computer memory consumption and improves computing efficiency.The detailed reaction networks of FTS wax hydrocracking can be generated smoothly and accu-rately by the current method.The work is the basis of advanced elementary-step-level kinetic modeling.     

Polyoxymethylene dimethyl ethers synthesis from methanol and formaldehyde solution over one-pot synthesized spherical mesoporous sulfated zirconia

The synthesis of polyoxymethylene dimethyl ethers as an ideal diesel fuel additive is the current hot topic of modern petrochemical industry for their expedient properties in mitigating air pollutants emission during combustion. In this work, a series of spherical sulfated zirconia catalysts were prepared by a one-pot hydrothermal method assisted with surfactant cetyltrimethylammonium bromide (CTAB). The prepared sulfated zirconia catalysts were used to catalyze PODE_n synthesis from methanol and formaldehyde solution. Various characterization (XRD, BET, SEM, TGA, NH₃-TPD, FTIR, and Py-IR) were employed to elaborate the structure–activity relationship of the studied catalytic system. The results demonstrated that S/Zr molar ratio in precursor solution played an effective role on catalyst morphology and acidic properties, where the weak Brønsted acid sites and strong Lewis acid sites were favorable to the conversion of methanol and formation of long-chain PODE_n, respectively. The reaction parameters such as catalyst amount, molar ratio of FA/MeOH, reaction time, temperature and pressure were optimized. The speculated reaction pathway for PODE_n synthesis was proposed based on the synergy of Brønsted and Lewis acid sites, which suggested that Brønsted and Lewis acid sites might be advantageous to the activation of polyoxymethylene hemiformals [CH₃(OCH₂)_nOH] and methylene glycol (HOCH₂OH), respectively.     

Promotional effect for SCR of NO with CO over MnOx-doped Fe3O4 nanoparticles derived from metal-organic frameworks

MnO_x-Fe₃O₄ nanomaterials were fabricated by using the innovative scheme of pyrolyzing manganese-doped iron-based metal organic framework in inert atmosphere and exhibited extraordinary performance of NO reduction by CO (CO-SCR). Multi-technology characterizations were conducted to ascertain the properties of fabricated materials (e.g., TGA, XRD, SEM, FT-IR, XPS, BET, H₂-TPR and O₂-TPD). Moreover, the interaction between reactants and catalysts was ascertained by in situ FT-IR. Experimental results demonstrated that Mn was an ideal promoter for iron oxides, resulting in decrease of crystallite size, improve reducibility property, enhance the mobility and the amount of lattice O^2- species, as well as strength the adsorption ability of active NO and CO to form multiple species (e.g., nitrate and carbonate). The unprecedented enhancement of CO-SCR activity over Mn-Fe nanomaterials follows the Eley-Rideal (E-R) and Langmuir-Hinshelwood (L-H) reaction pathway.     

A core–shell Ni/SiO2@TiO2 catalyst for highly selective one-step synthesis of 2-propylheptanol from n-pentanal

One-step synthesis of 2-propylheptanol (2-PH) from n-pentanal via a reaction integration of n-pentanal self-condensation and successive hydrogenation is of great significance for it can simplify process flow and reduce energy consumption. The key to promotion of 2-PH selectivity is to enhance the competitiveness of n-pentanal self-condensation with respect to its direct hydrogenation. For this purpose, a core–shell structured Ni/SiO₂@TiO₂ catalyst was designed and prepared. With the precise architecture of this core–shell structured catalyst, n-pentanal can be firstly in contact with TiO₂ to 2-propyl-2-heptenal (2-PHEA) while the direct hydrogenation to n-pentanol can be effectively inhibited, and then 2-PHEA diffuses into the core of Ni/SiO₂ and is hydrogenated to 2-PH. The spatial threshold of the core–shell catalyst significantly enhanced its catalytic performance; a 2-PH selectivity of 77.9% was reached with a 100% n-pentanal conversion. The 2-PH selectivity is much higher than that obtained by employing Ni/TiO₂ catalyst. Furthermore, the reaction kinetics of one-step synthesis of 2-PH from n-pentanal catalyzed by Ni/SiO₂@TiO₂ was studied and its kinetic model was established which is useful for reactor design and scale-up.     

Formation of bromo-substituted triclosan during chlorination by chlorine in the presence of trace levels of bromide

The side reactions of triclosan (2,4,4'-trichloro-2'-hydroxydiphenyl ether, TC) and chlorine in the presence of sodium chloride were investigated. In the absence of sodium chloride, three chloro-derivatives of TC, 2',3,4,4'-tetrachloro-2-hydroxydiphenyl ether (3-Cl-TC), 2',4,4',5-tetrachloro-2-hydroxydiphenyl ether (5-Cl-TC), and 2',3,4,4',5-pentachloro-2-hydroxydiphenyl ether (3,5-Cl(2)-TC) were formed, whereas in the presence of sodium chloride, 3-bromo-2',4,4'-trichloro-2-hydroxydiphenyl ether (3-Br-TC), 5-bromo-2',4,4'-trichloro-2-hydroxydiphenyl ether (5-Br-TC), (3 or 5)-bromo-2',4,4',(5 or 3)-chloro-2-hydroxydiphenyl ether ((3,5)-(BrCl)-TC), and 3,5-dibromo-2',4,4'-trichloro-2-hydroxydiphenyl ether (3,5-Br(2)-TC) were additionally formed. Radiochemical neutron activation analysis indicated that 1g of commercially available sodium chloride contained 73 microg of bromide and the bromide ion was determined to be the source of the side reactions. The rate of decrease of TC due to reaction with chlorine was greatly accelerated by the presence of bromide ion in the system: the rate with only 1 x 10(-5) M bromide ion was three times the rate in the absence of bromide.     

渗透结晶型液体硬化剂表面处理方法及作用机理研究

阐述了渗透结晶型表面处理剂的作用机理。渗透结晶型表面处理剂渗透进入水泥基内部后,与水泥的水化产物发生反应可以生成新的晶体来填补水泥缝隙,使基体更加密实,研究发现,这是通过与水泥基的化学反应增强机制来实现强化的。本文主要介绍了氟硅酸盐与水泥基材料的作用机理,并初步研究了氟硅酸盐表面硬化的处理方法。     

Review on the Reactivity of 1,1‐Diamino‐2,2‐dinitroethylene (FOX‐7)

1,1‐Diamino‐2,2‐dinitroethylene (FOX‐7) is a novel high‐energy insensitive material with good thermal stability and low sensitivity, and exhibits excellent application performance in the field of insensitive ammunitions and solid propellant. Although FOX‐7 is simple in molecular composition and structure, its chemical reactivity is abundant and surprising, including salification reaction, coordination reaction, nucleophilic substitution reaction, acetylate reaction, oxidizing reaction, reduction reaction, electrophilic addition reaction, among other reactions. These reactions are systemically summarized and some reaction mechanisms are analyzed in this review.     

氯代烷烃对气相缩合法合成苯基三氯硅烷的影响(英文)

To enhance the process of phenyltrichlorosilane synthesis using gas phase condensation, a series of chloralkanes were introduced. The influence of temperature and chloralkane amount on the synthesis was studied based on the product distribution from a tubular reactor. The promoting effect of chloralkane addition was mainly caused by the chloralkane radicals generated by the dissociation of C–Cl bond. The promoting effect of the chloromethane with more chlorine atoms was better than those with less chlorine atoms. Intermediates detected from the reactions with isoprene and bromobenzene demonstrated that both trichlorosilyl radical and dichlorosilylene existed in the reaction system in the presence of chloralkanes. A detailed reaction scheme was proposed.