含硅冠醚化合物的合成及其催化活性

合成了两种新型的含硅冠醚化合物。它们的结构经元素分析、ＩＲ和１ＨＮＭＲ表征。并对其相转移催化活性进行了考察。

高软化点聚碳硅烷的合成及可纺性

采用聚二甲基硅烷经常压高温裂解法合成了聚碳硅烷（PCS）,研究了不同反应条件下缩聚反应的特点与分子量增长的模式,探讨了聚碳硅烷的结构与可纺性之间的关系.结果表明,对应于不同分子量PCS之间的缩聚反应,高温下PCS的缩聚反应分为分子量匀速增长和加速增长2种模式.经匀速增长模式得到的PCS分子量呈双峰分布,具有良好的可纺性,而经加速增长模式得到的PCS因含有大量的支化结构,分子量呈多峰分布,可纺性较差,甚至丧失可纺性.通过控制反应条件使缩聚反应中分子量增长处于匀速模式,合成了软化点为256-287℃,数均分子量为2.3×10 3且具有良好可纺性的聚碳硅烷.

完美骨架全硅β沸石性质研究 Ⅰ.合成全硅β沸石与脱铝β沸石的性质比较

以四乙基氢氧化铵为模板剂 ,正硅酸乙酯为硅源 ,静置水热法合成全硅 β沸石 .用硝酸 (13mol/L)对硅铝比(Si/Al)为 2 0的Na β沸石回流脱铝 .焙烧后的上述两样品经粉末X射线衍射、低温氮吸附、核磁共振、红外光谱、吸附等温线等表征 ,发现合成的全硅 β沸石骨架与孔道结构完美并具有很高的表面疏水 /亲有机物的吸附特性 .

芳基硅烷合成研究进展

芳基硅烷广泛应用于Hiyama偶联、C-N偶联、联芳烃及聚酮高分子化合物合成等方面,其合成研究受到关注.文章对近二十年来芳基硅烷的合成研究进行概述,发现利用贵金属催化剂催化芳基硅烷合成,虽然产物收率高、底物适用性好、反应时间短、反应条件温和,但也存在着催化剂成本高、难以回收利用的问题.非贵金属催化剂的开发研究以及催化剂循环利用将是今后重点关注的方向.

合成润滑剂的现状及发展

介绍了合成润滑剂的发展概况和国内目前存在的主要问题,提出发展我国合成润滑剂的建议。

Fabrication and characterization of tungsten-containing mesoporous silica for heterogeneous oxidative desulfurization

A series of functional,tungsten-containing mesoporous silica materials（W-SiO2） have been fabricated directly from an ionic liquid that contained imidazole and polyoxometalate,which acted as mesoporous template and metal source respectively.These materials were then characterized through X-ray diffraction（XRD）,transmission electron microscopy（TEM）,Raman spectroscopy,Fourier transform infrared spectra（FTIR）,diffuse reflectance spectra（DRS）,and N2 adsorption-desorption,which were found to contain tungsten species that were effectively dispersed throughout the structure.The as-prepared materials W-SiO2 were also found to possess a mesoporous structure.The pore diameters of the respective sample W-SiO2-20 determined from the TEM images ranged from 2 to 4 nm,which was close to the average pore size determined from the nitrogen desorption isotherm（2.9 nm）.The materials were evaluated as catalysts for the heterogeneous oxidative desulfurization of dibenzothiophene（DBT）,which is able to achieve deep desulfurization within 40 min under the optimal conditions（Catalyst（W-SiO2-20）= 0.01 g,temperature = 60℃,oxidant（H2O2）= 20 μL）.For the removal of different organic sulfur compounds within oil,the ability of the catalyst（W-SiO2-20） under the same conditions to remove sulfur compounds decreased in the order：4,6-dimethyldibenzothiophene Dibenzothiophene Benzothiophene 1-dodecanethiol.Additionally,they did not require organic solvents as an extractant in the heterogeneous oxidative desulfurization process.After seven separate catalytic cycles,the desulfurization efficiency was still as high as 90.3%.From the gas chromatography-mass spectrometer analysis,DBT was entirely oxidized to its corresponding sulfone DBTO2 after reaction.A mechanism for the heterogeneous desulfurization reaction was proposed.

Synthesis and characterization of copolyimides from bis(3,4-dicarboxyphenyl)dimethylsilane dianhydride

The silicon-containing poly (amic acid)s were synthesized from bis (3, 4-dicarboxyphenyl) dimethylsilane dianhydride (SIDA), pyromellitic dianhydride (PMDA) and 4,4′-oxydianiline (4,4'-ODA) in N, N-dimethylacetamide (DMAc). The poly (amic acid) films were obtained by solution-cast method from DMAc solutions and thermally converted into transparent, flexible and tough polyimide films. The wide-angle X-ray diffraction diagrams revealed that all the polyimides possessed amorphous character, and the regulation of those polyimides were decreased with the increase of the molar ratio of SIDA to PMDA. Differential scanning calorimeter measurements showed that the introduction of SIDA to polyimide backbone would make glass transition temperature shift to lower temperature. Thermogravimetric analyses indicated that the silicon-containing polyimides lowered decomposition temperature as compared with PMDA/4, 4′-ODA polyimides. However, UV-visible transmission and reflection spectra showed that the optical transparency of silicon-containing polyimide thin films was superior to that of PMDA/4, 4'-ODA polyimide thin films.

Charge compensation dominates the distribution of silica in SAPO-34

The distribution of Si atoms in the SAPO-34 framework determines its acidity and catalytic effects.This was investigated using the charge balance between the inorganic framework and trapped template ions.Three types of templates,which yielded R~＋,2R~＋ and 2R^（2＋） positive charges in the cages of SAPO-34,were obtained from single crystal data and they were used to direct the synthesis of SAPO-34 with different Si contents and formation of isolated Si atoms and Si islands in the lattice.The concentration limits of SiO2 in the gel for constituting isolated Si atoms were calculated and verified experimentally.Si islands,including 5-Si,8-Si,11-Si,14-Si island were described on the basis of host-guest charge compensation.An overall view of the distribution of Si atoms in SAPO-34 was given and a criterion for the strength and density of acid sites in SAPO-34 for it to be an efficient catalyst for MTO was made available.

Synthesis and Characterization of Waterborne Epoxy Curing Agent Modified by Silane

A novel waterborne epoxy curing agent was prepared using 3-glycidoxypropyl trimethoxysilane （GPTMS） as a termination agent of adduct, which was synthesized by triethylene tetramine （TETA） and liquid epoxy resin （E-51）. The effects of the reaction temperature and time on the synthesis process were investigated experimentally. The particle size and the distribution of water dispersion of the curing agent were measured by dynamic light scattering（DLS）. The structure of the products was characterized by Fourier transform infrared spec-trometer （FTIR） and ^1H-nuclear magnetic resonance （^1H NMR）. The properties of the synthesized curing agent and the epoxy resin film cured by it were also measured. The results showed that the appropriate temperature for the synthesis of adduct was at 65-75℃ and the reaction time was 4-5h, and that the suitable reaction temperature of curing agent synthesis was 75-85℃ and the reaction time was 3-4h. When the mass ratios of GPTMS and acetic acid were 3%-5% and 5%-10% respectively, the hardness, water resistance and adhesion of the cured film were improved significantly.

Growth of Cu/SSZ-13 on SiC for selective catalytic reduction of NO with NH_3

Silicon carbide(SiC)was used as a support for SSZ‐13zeolite in an attempt to improve the high‐temperature stability and activity of Cu/SSZ‐13in the selective catalytic reduction(SCR)of NO with NH3.SSZ‐13was grown via a hydrothermal method using the silicon and silica contained in SiC as the source of silicon,which led to the formation of a chemically bonded SSZ‐13layer on SiC.Characterization using X‐ray diffraction,scanning electron microscopy,and N2adsorption‐desorption isotherms revealed that the alkali content strongly affected the purity of zeolite and the crystallization time affected the coverage and crystallinity of the zeolite layer.Upon ion exchange,the resulting Cu/SSZ‐13@SiC catalyst exhibited enhanced activity in NH3‐SCR in the high‐temperature region compared with the unsupported Cu/SSZ‐13.Thus,the application temperature was extended with the use of SiC as the support.?2018,Dalian Institute of Chemical Physics,Chinese Academy of Sciences.Published by Elsevier B.V.All rights reserved.

Synthesis and ceramization of polycarbosilane containing beryllium

Polycarbosilane containing beryllium(BPCS) precursors was prepared by the reaction of polycarbosilane(PCS) with beryllium acetylacetone(Be(acac)2).The analysis of structures and components of BPCS demonstrates that their main structures are basically the same as PCS.Ceramization of BPCS precursors shows that BPCS precursors are organic below 600 °C and inorganic at 800 °C.At 1400 °C,BPCS precursors convert into silicon carbide ceramics.The ceramization of different beryllium content precursors were studied,which show that beryllium plays an important role in the inhibition of crystalline grain growth of β-SiC at high temperature and it can adjust the dielectric constant of silicon carbide ceramics.

Effects of SiC amount on phase compositions and properties of Ti_3SiC_2-based composites

The phase compositions and properties of Ti3SiC2-based composites with SiC addition of 5%-30% in mass fraction fabricated by in-situ reaction and hot pressing sintering were studied. SiC addition effectively prevented TiC synthesis but facilitated SiC synthesis. The Ti3SiC2/Ti C-SiC composite had better oxidation resistance when SiC added quantity reached 20% but poorer oxidation resistance with SiC addition under 15% than Ti3SiC2/TiC composite at higher temperatures. There were more than half of the original SiC and a few Ti3SiC2 remaining in Ti3SiC2/Ti C-SiC with 20% SiC addition, but all constituents in Ti3Si2/TiC composite were oxidized after 12 h in air at 1500 °C. The oxidation scale thickness of TS30, 1505.78 μm, was near a half of that of T,2715 μm, at 1500 °C for 20 h. Ti3SiC2/Ti C composite had a flexural strength of 474 MPa, which was surpassed by Ti3SiC2/TiC-SiC composites when SiC added amount reached 15%. The strength reached the peak of 518 MPa at 20% SiC added amount.

Synthesis of acetals and ketals catalyzed by tungstosilicic acid supported on active carbon

Catalytic activity of activated carbon supported tungstosilicic acidin synthesizing 2-methyl-2-ethoxycarbonylmethyl- 1,3-dioxolane, 2,4-dimethyl-2-ethoxycarbonylmethyl-1,3-dioxolane, cyclohexanone ethylene ketal, cyclohexanone 1,2-propa- nediol ketal, butanone ethylene ketal, butanone 1,2-propanediol ketal, 2-phenyl-1,3-dioxolane, 4-methyl-2-phenyl-1,3-dioxolane, 2-propyl-1,3-dioxolane, 4-methyl-2-propyl-1,3-dioxolane was reported. It has been demonstrated that activated carbon supported tungstosilicic acid is an excellent catalyst. Various factors involved in these reactions were investigated. The optimum conditions found were: molar ratio of aldehyde/ketone to glycol is 1/1.5, mass ratio of the catalyst used to the reactants is 1.0%, and reaction time is 1.0 h. Under these conditions, the yield of 2-methyl-2-ethoxycarbonylmethyl-1,3-dioxolane is 61.5%, of 2,4-dimethyl- 2-ethoxycarbonylmethyl-1,3-dioxolane is 69.1%, of cyclohexanone ethylene ketal is 74.6%, of cyclohexanone 1,2-propanediol ketal is 80.1%, of butanone ethylene ketal is 69.5%, of butanone 1,2-propanediol ketal is 78.5%, of 2-phenyl-1,3-dioxolane is 56.7%, of 4-methyl-2-phenyl-1,3-dioxolane is 86.2%, of 2-propyl-1,3-dioxolane is 87.5%, of 4-methyl-2-propyl-1,3-dioxolane is 87.9%.

Synthesis of mesoporous high‐silica zeolite Y and their catalytic cracking performance

Mesoporous high‐silica zeolite Y with advantages of improved accessibility of acid sites and mass transport properties is highly desired catalytic materials for oil refinery,fine chemistry and emerg‐ing biorefinery.Here,we report the direct synthesis of mesoporous high‐silica zeolite Y(named MSY,SiO_(2)/Al2O_(3)≥9.8)and their excellent catalytic cracking performance.The obtained MSY mate‐rials are mesoporous single crystals with octahedral morphology,abundant mesoporosity and ex‐cellent(hydro)thermal stability.Both the acid concentration and acid strength of H‐form MSY are obviously higher than those of commercial ultra‐stable Y(USY),which should be attributed to the uniform Al distribution of MSY zeolite.The H‐MSY displays an obviously reduced deactivation rate and improved catalytic activity in the cracking reaction of bulky 1,3,5‐triisopropylbenzene(TIPB),as compared with its mesoporogen‐free counterpart and USY.In addition,H‐MSY was investigated as catalyst for the cracking of industrial heavy oil.The MSY‐based catalyst(after aging at 800 oC in 100%steam for 17 h)exhibits superior conversion(7.64%increase)and gasoline yield(16.37%increase)than industrial fluid catalytic cracking(FCC)catalyst under the investigated conditions.

Synthesis of Silica-Dispersed NiMo Hydrodesulfurization Catalysts

Silica-dispersed NiMo hydrodesulfurization catalysts were synthesized by the deposition-precipitation method. For comparative purposes, bulk NiMo catalysts were obtained by co-precipitation. The silica-dispersed NiMo catalyst had highly active metals content. Silica was employed to disperse active metals for full utilization of active components. The BET analysis showed that the silica-dispersed NiMo catalysts had a high surface area （147.0 m2/g） and pore volume （0.27 mL/g）, whereas the bulk NiMo catalysts exhibited a very low surface area （87.5 m2/g）. Transmission electron microscopy results proved that the active components were dispersed on the SiO2 substrate. X-ray diffraction patterns of the silicadispersed NiMo catalyst and the bulk NiMo catalyst were indexed to NiMoO4. The hydrodesulfurization activity of silicadispersed NiMo catalysts was much higher than that of reference catalysts and could be up to twice greater than those of commercial NiMo alumina-supported systems per gram of catalyst. The activity testing results also demonstrated that the silica-dispersed NiMo catalyst was an effective hydrodesulflarization catalyst.

A Bi-component Cu Catalyst for the Direct Synthesis of Methylchlorosilane from Silicon and Methyl Chloride

A bi-component catalyst comprising CuC1 and metallic copper was used in the direct synthesis of me- thylchlorosilane to study the catalytic synergy between the different copper sources. The catalyst exhibited high ac- tivity and high selectivity of dimethyldichlorosilane （M2） in the stirred bed reactor. The effect of the proportion of CuC1 used was studied and 10%-30% CuC1 gave the best yield of M2. The use of CuC1 decreased the induction pe- riod of reaction, improved the selectivity in the induction stage, and gave a longer stable stage. These results sug- gest that bi-comoonent catalyst has advantazes in the direct synthesis reaction.

Al-modified mesocellular silica foam as a superior catalyst support for dibenzothiophene hydrodesulfurization

A series of Al‐containing mesostructured cellular silica foams(Al‐MCFs)with different Si/Al molar ratios(x;x=10,20,30,40,or50)were prepared by a post synthetic method using aluminum isopropoxide as an alumina source.The corresponding NiMo catalysts supported on Al‐MCFs were prepared and evaluated using dibenzothiophene(DBT)as the probe reactant.All the synthesized samples were characterized by small‐angle X‐ray scattering,scanning electron microscopy,nitrogen adsorption‐desorption,UV‐Vis diffuse reflectance spectroscopy,H2temperature‐programmed reduction,27Al MAS NMR,temperature‐programmed desorption of ammonia,pyridine‐FTIR,Raman spectroscopy,HRTEM,and X‐ray photoelectron spectroscopy to analyze their physicochemical properties and to gain a deeper insight of the interrelationship between the structures and the catalytic performance.The synthesis mechanism was proposed to involve the formation of Br?nsted acid and Lewis acid sites through the replacement of Si4+with Al3+.Aluminum introduced into MCFs by the post synthetic method has a negligible influence on the mesostructure of the parent MCFs but can form silicoaluminate materials with moderate Br?nsted acidity.For Al‐MCFs(x)materials,the detection of tetrahedrally coordinated Al3+cations demonstrated that the Al species had been successfully incorporated into the silicon frameworks.Furthermore,the DBT hydrodesulfurization(HDS)catalytic activity of the NiMo/Al‐MCFs(x)catalysts increased with increasing Si/Al molar ratio,and reached a maximum at a Si/Al molar ratio of20.The interaction of Ni and Mo species with the support became stronger when Al was incorporated into the MCFs supports.The high activities of the NiMo/Al‐MCFs catalysts for the DBT HDS were attributed to the suitable acidity properties and good dispersions of the Ni and Mo active phases.

Synthesis and Crystal Structure of Na_(10)[LaSiW_(11)O_(39)(H_2O)_4]_2·22H_2O

The complex Na10[LaSiW11O39(H2O)4]2?2H2O was synthesized and crystallized in monoclinic,space group P21/n with cell parameters: a=17.9786(9), b=23.5940(2), c=13.1289(8), β=90.141(2)°, V=5569.1(6)3, Mr=6336.60, Z=2, Dc=3.779g/cm3, (MoKa)= 0.71069? =23.533mm-1, F(000)=5488, T=293(2)K. The final refinement for 8404 observed reflections with I >2s (I) gave R = 0.0595 and wR = 0.1366. Both lanthanide cations are coordinated by nine oxygen atoms in a distorted squareantiprism environment. The LaO bond lengths are from 2.52(1) to 2.63(2).

Formation kinetics and transition mechanism of CaO·SiO2 in low-calcium system during high-temperature sintering

The crystal structure,formation kinetics and micro-morphology of CaO·SiO2 during high-temperature sintering process were studied in low-calcium system by XRD,FT-IR,Raman and SEM-EDS methods.When the molar ratio of CaCO3 to SiO2 is 1.0,β-2CaO·SiO2 forms firstly during the heating process,and then CaO·SiO2 is generated by the transformation reaction of pre-formed 2CaO·SiO2 with SiO2.3CaO·SiO2 and 3CaO·2SiO2 do not form either in the heating or sintering process.Rising the sintering temperature and prolonging the holding time promote the phase transition of 2CaO·SiO2 to CaO·SiO2,resulting in the sintered products a small blue shift and broadening in Raman spectra.The content of CS can reach 97.4%when sintered at 1400℃ for 1 h.The formation kinetics of CaO·SiO2 follows the second-order chemical reaction model,and the corresponding apparent activation energy and pre-exponential factor are 505.82 kJ/mol and 2.16×10^14 s^−1 respectively.