清洁法制备全结晶ZSM-5分子筛催化剂及其催化性能

在无额外添加碱金属或碱土金属的体系中,以氨水为模板剂,成功制备全结晶ZSM-5分子筛催化剂。晶化结束后,采用闪蒸技术回收晶化残液中的氨水,回收率高达85%,并且实现了回收氨水的循环再利用,连续回用3次仍然可以得到高结晶的分子筛催化剂。表征结果表明,通过优化合成配方,在晶化温度为170℃,晶化时间为6 h的条件下,制备的全结晶ZSM-5分子筛催化剂具有晶体形貌规整、晶间孔丰富、活性中心状态好、机械强度高(108 N·cm^(-1))等优点。在稀乙烯和苯气相烷基化制乙苯反应中,全结晶ZSM-5分子筛催化剂表现出优异的活性、选择性、稳定性及再生性能,关键杂质二甲苯含量仅为(350~400)μL·L^(-1),完全可以满足工业应用需求。

共结晶分子筛催化剂上催化裂化汽油中烯烃芳构化

针对共结晶分子筛催化剂CDM35的特点，开发了适宜催化裂化汽油和液化气改质的高芳烃低烯烃的循环固定流化床工艺。在质量空速1.0-2.0h^-1,370-420℃、200g CDM35、循环量10％～20％的条件下，对催化裂化汽油和／或液化气进行改质，可得到烯烃质量分数20％左右、芳烃质量分数40％左右、苯质量分数〈1％汽油辛烷值（RON）95以上的汽油产品。

结晶氯化镁—氯化铵混合硬化剂制壳工艺

介绍结晶氯化镁———氯化铵混合硬化剂的配制方法和硬化工艺方法。采用该工艺后,提高型壳的品质,改善生产环境,降低生产成本。

新型无机硬化剂在翻新地坪中应用及施工工法

BANDě邦地美■水晶地坪液体硬化剂应用于老旧建筑的改造,可不拆除原有的结构层及找平层,不产生建筑垃圾,完成后实现了地坪装饰面与原建筑同寿命。在旧改项目中实现了地面施工近零能耗,保证地坪装饰面的全生命周期的节能环保健康。

柠檬酸处理对FCC干气与苯烷基化催化剂的影响

采用ZSM-5/ZSM-11共结晶分子筛催化剂,在固定床反应装置上对催化裂化干气与苯制乙苯进行考察。NH3-TPD结果表明,随着水热处理条件的苛刻,催化剂的酸量和酸强度均下降,虽然这些催化剂上干气中乙烯转化率变化不明显,但产物中二甲苯含量大幅度下降。柠檬酸对分子筛催化剂进行改性处理后,可明显降低催化裂化干气与苯制乙苯中二甲苯杂质含量,原因可能为催化剂大的比表面积和孔容改善了原料的传质能力,从而抑制了二甲苯的生成。

复合结晶银催化剂的制备及催化性能

应用超声波电解法制备了La2O3/Ag复合银催化剂.利用SEM,XRD等手段对负载不同氧化镧含量的催化剂研究结果表明:电解过程中嵌入少量氧化镧,结晶银的晶体结构得到保持,催化剂的抗烧结性能得到显著提高.以丙二醇选择性催化氧化为反应体系,比较了1%La2O3/Ag复合结晶银和工业结晶银催化剂的催化活性和稳定性,实验结果表明:复合结晶银催化剂的低温氧化活性受到部分抑制,但是催化剂稳定性和反应选择性得到显著提高.

Structured binder‐free MWW‐type titanosilicate with Si‐rich shell for selective and durable propylene epoxidation

Selective and durable fixed‐bed catalysts are highly desirable for developing eco‐efficient HPPO(hydrogen peroxide propylene oxide)process.The powder titanosilicate catalysts must be shaped before being applied in industrial processes.As the essential additives for preparing formed catalysts,binders are usually the catalytically inert components,but they would cover the surface and pore mouth of zeolite,thereby declining the accessibility of active sites.By recrystallizing the binder(silica)/Ti‐MWW extrudates with the assistance of dual organic structure‐directing agents,the silica binder was converted into MWW zeolite phase to form a structured binder‐free Ti‐MWW zeolite with Si‐rich shell,which enhanced the diffusion efficiency and maintained the mechanical strength.Meanwhile,due to the partial dissolution of Si in the Ti‐MWW matrix,abundant silanol nests formed and part of framework TiO4 species were transferred into open TiO_(6)ones,improving the accumulation and activation ability of H_(2)O_(2)inside the monolith.Successive piperidine treatment and fluoridation of the binder‐free Ti‐MWW further enhanced the H_(2)O_(2)activation and oxygen transfer ability of the active Ti sites,and stabilized the Ti‐OOH intermediate through hydrogen bond formed between the end H in Ti‐OOH and the adjacent Si‐F species,thus achieving a more efficient epoxidation process.Additionally,the side reaction of PO hydrolysis was inhibited because the modification effectively quenched numerous Si‐OH groups.The lifetime of the modified binder‐free Ti‐MWW catalyst was 2400 h with the H_(2)O_(2)conversion and PO selectivity both above 99.5%.

Nickel and aluminium recovery from spent reforming catalyst through selective leaching,crystallization and precipitation

An attempt has been made to investigate and optimize the recovery of Ni and Al through sulphuric acid(3.0-5.5 mol/L)leaching under different operating conditions.From the leaching experiments,it was possible to extract 98.5%of NiO and 40.7%of Al_(2)O_(3)under the conditions of 5.5 mol/L H_(2)SO_(4),reaction time of 4 h,solid-to-liquid ratio 0.2 g/mL,temperature of 358 K,particle size<100μm,200-250 r/min with 5.0 g catalyst dosage.The leached liquor Al was separated by selective crystallization using 1.4 mol/L KOH and Ni was separated by selective precipitation using 0.3 mol/L H_(2)C_(2)O_(4).From the studies,it is possible to recover around 97.9%of NiO having 98.3%purity,around 25%of Al_(2)O_(3)was also recovered as alum-(K)having 99%purity and 14.7%of Al_(2)O_(3)as a salt of Al-K-C_(2)O_(4)-SO_(4).Sulphuric acid was found to be a suitable leaching agent for selective leaching and it was also observed that alum-(K)can be selectively crystallized from sulphate solutions.The study also indicated the effective extraction and recovery of nickel and aluminium which were well supported by characterization studies using TG-DTA/DTG and XRD techniques.

Crystal Growth,Structure and Morphology of Rifapentine Methanol Solvate

Rifapentine, an important antibiotic, was crystallized from methanol solvent in the form of its methanol solvate. The crystal structure of rifapentine methanol solvate belongs to monoclinic, space group P21, with the unit cell parameters of a = 1.2278（3） nm, b = 1.9768（4） rim, c = 1.2473（3） nm, Z= 2, and β = 112.35（3）. The parallelepiped.morphology was also predicted by Materials Studio simulation program.. The influence of intermolecular in-teraction was taken into account in the attachment energy model. The crystal shape fits the calculated morphology well, which was performed on the potential energy minimized model using a generic DREIDING 2.21 force fieldand developed minimization protocol with derived＇partial charges.

Experimental research on influence of emulsifier on crystallization quantity of emulsion explosives under dynamic pressure

Dynamic pressure was applied on emulsion explosive by using an underwater explosion measuring apparatus, and the crystallization quantity was measured by dissolution method after emulsion explosive was pressed; the influence of emulsi- fier content and type was analyzed. The experimental results show that emulsifier content and type have an important effect on crystallization quantity of emulsion explosive. The crystallization quantity will reduce with Span-g0 content from 2% to 4%, so the demulsification and crystallization will decrease if the emulsifier content improves appropriately and the dynamic pressure resistance will increase. For emulsion explosive emulsified by T-152 and Span-g0, the crystallization quantity with T-152 is less than that of Span-g0 under the same dynamic pressure. This shows that the emulsifying effect ofT-152 is better than Soan-80.

Effect of Additive EDTA on Crystallization Process of Magnesium Hydroxide Precipitation

The effects of additive ethylenediaminetetraacetic acid (EDTA) on crystallization process were investigated by the induction time of MgSO 4-NaOH system. Nucleation and growth rates, growth mechanism and particle size distribution of magnesium hydroxide precipitation were involved with. The induction time in unseeded and seeded precipitation of magnesium hydroxide with and without additive EDTA was measured. The conductivity method was used to determine the induction period. Theoretical relations of the induction time and supersaturation ratio for different growth mechanisms and a combined analysis on the induction time were applied to determine nucleation and growth rates. The growth mechanism of magnesium hydroxide precipitation was disclosed by analyzing the experimental data with and without additive. The analysis on induction time indicated that additive EDTA had a significant influence on both nucleation and growth of magnesium hydroxide precipitation. The mechanism underlying the effect of EDTA on crystal growth was 2-dimension nucleation-mediated growth model.

Crystal Structure and Spectroscopic Studies of Diphenylcarbazide Acetonitrile Solvate,(PhNHNH)_2C=O·CH_3CN

The title compound (PhNHNH)2C=OCH3CN has been prepared and characterized by elemental analysis and IR spectrum studies. The single-crystal X-ray structure determination of the title compound was carried out. It crystallizes in the monoclinic system, space group P21/n with a = 5.7818(2), b = 15.320(1), c = 17.469(1) ? b = 97.476(1)? V = 1534.2(1) 3, Mr = 283.34 (C15H17N5O), Z = 4, Dc = 1.227 g/cm3 , F(000) = 600, ?= 0.082 mm-1, R = 0.0561 and wR = 0.1538. The total reflections were 8214 and the independent ones were 2624 (Rint = 0.0559), of which 1756 were observed with I > 2s(I). The torsion angles of the important groups (C(6)N(1) N(2)C(7) and C(7)N(3)N(4)C(8)) are 68.3(3) and 93.3(3), respectively. In the crystal lattice, the molecules form a network structure through hydrogen bonds. The crystal structure is stabilized by NH…N and NH…O hydrogen bonds. FT-IR spectra clearly show there exist acetonitrile molecules in the crystal lattice.

Microstructural evolution during partial remelting of AM60B magnesium alloy refined by MgCO_3

AM60B magnesium alloy was refined by MgCO3 and its microstmcturat evolution was investigated during partial remelting. The results indicate that MgCO3 is an effective grain refiner for AM60B alloy and can decrease the grain size from 329 pm of the unrefined alloy to 69 μm. A semisolid microstructure with small and spheroidal primary particles can be obtained after being partially remelted. The microstructure evolution can be divided into four steps： the initial rapid coarsening, structure separation, spheroidization and final coarsening. Correspondingly, these four steps result from the phase transformations of β→α, α＋β→L and α→L, α→L and two reverse reactions of α→L and L→α, respectively. One spheroidal primary particle in the semisolid microstmcture usually originates one dendrite in the as-cast microstructure. The variation of primary particle size with holding time does not obey the LSW law, Dt^3-Do^3=Kt, after the semisolid system is in its solid-liquid equilibrium state. Longer heating duration makes the primary particles more globular, but it makes their size larger at the same time.

Theoretical Calculation on Optimum Si-doping Content in Boron Carbide Thin Film

The theoretical expression of the relationship between optimumdoping content and crystal structure is presented as well as thepreparation methods. By using this expression, the optimum dopingcontent of silicon-coped boron carbide thin film is calculated. Thequantitative calculation value is consistent with the experimentalresults. This theoretical expression is also appropriate to resolvethe optimum doping content for Other electric materials.

Synthesis and Characterization of ZnO Bicrystalline Nanosheets Grown via Ag-Au Alloy Catalyst

ZnO bicrystalline nanosheets have been synthesized by using Ax=AU1-x alloy catalyst via the vapor transport and condensation method at 650 ℃. High resolution transmission electron microscopy characterization reveals a twin boundary with {01-13} plane existing in the bicrystalline. A series of control experiments show that both AgxAu1-x alloy catalyst and high supersaturation of Zn vapor are prerequisites for the formation of ZnO bicrystalline nanosheet. Moreover, it is found that the density of ZnO bicrytalline nanosheets can be tuned through varying the ratio of Ag to Au in the alloy catalyst. The result demonstrates that new complicated nanostructures can be produced controllably with appropriate alloy catalyst.

Effects of Non-specific and Specific Solvation on Adsorption of BPTI on Au Surface： Insight from Molecular Dynamics Simulation

Proteins adsorption at solid surfaces are of paramount important for many natural processes. However, the role of specific water in influencing the adsorption process has not been well understood. We used molecular dynamics simulation to study the adsorption of BPTI on Au surface in three water environments （dielectric constant model, partial and full solvation models）. The result shows that a fast and strong adsorption can occur in the dielectric environment, which leads to significant structure changes, as confirmed by great deviation from the crystal structure, largely spreading along the Au surface, rapid lose in all secondary structures and the great number of atoms in contact with the surface. Compared to the dielectric model, slower adsorption and fewer changes in the calculated properties above are observed in the partial solvation system since the specific water layer weakens the adsorption effects. However, in the partial solvation system, the adsorption of polar Au surface causes a significant decrease in the specific hydration around the protein, which still results in large structure changes similar to the dielectric system, but with much less adsorption extent. Enough water molecules in the full solvation system could allow the protein to rotate, and to large extent preserve the protein native structure, thus leading to the slowest and weakest adsorption. On the whole, the effects of non-specific and specific solvation on the protein structure and adsorption dynamics are significantly different, highlighting the importance of the specific water molecule in the protein adsorption.

Crystal Structure of Carboxypeptidase a Complexed with an Inactivator in a New Crystalline Form

A new crystalline form of carboxypeptidase A (CPA) complexes withan inactivator was obtained by the method of hanging drop vapor diffusion. The inacti-’vator, 2-benzyl-3-iodo-propanoic acid (BIPA ), binds covalently to an active siteresidue Glu-27O of CPA. The complex was crystallized in space group P212121 with a= 48. 8 A, b=66. 9 A, c= 96. 0 A. The complex structure was determined by molecu-lar replacement using the native CPA crystal structure as the search model. The finalcrystallographic residual is 0. 152. Except for the modification of Glu-270, the inactiva-tor exhibits normal binding mode compared with other ligand complexes of CPA. Inthe final different electron density maps (2Fo-Fc, Fo-Fc), the density of the iodo ioncould not be found while the conserved molecule remains coordinated to Zn2+ as in thenative CPA. Comparisons of complex of CPA-BIPA with the native CPA and theCPA/D-Phe complex are presented. The mechanism of inactivation of CPA was dis-cussed.