Cu-embedded porous Al2O3 bifunctional catalyst derived from metal–organic framework for syngas-to-dimethyl ether

Dimethyl ether （DME）,as a promising alternative to diesel fuel and liquefied petroleum gas,has attracted considerable attention in catalysis domain.The catalytic direct synthesis of DME from syngas is an upand-coming route but remains a challenge.In this work,we firstly prepared a Cu-embedded porous Al₂O₃bifunctional catalyst （Cu@Al₂O₃-dp） by filling Cu-1,3,5-benzenetricarboxylate metal–organic framework（Cu-BTC MOF） with Al（OH）₃followed by a...     

LaCoO3对H2S选择氧化性能的影响

使用溶胶-凝胶法制备了LaCoO₃催化剂,采用XRD、BET和XPS等方式对催化剂进行了表征,考察了该催化剂制备过程中煅烧温度、表面活性剂PEG-6000和PEG-20000含量对其H₂S选择氧化制硫磺反应催化活性的影响。结果表明,表面活性剂PEG-6000及PEG-20000的添加能明显提高LaCoO₃的催化活性。0.02 mol La（NO₃）₃+0.02mol Co（NO₃）₂溶液中添加0.30 g PEG-20000、煅烧温度为650℃时所制备的LaCoO₃催化活性最好;在最佳反应温度260℃下,H₂S的转化率达到96.10%,硫选择性为93.77%。     

K3H3[As2W21O69（H2O）]·19H2O的合成及晶体结构（英文）

利用二缺位K14[As2W19O67]·nH2O前驱体在酸性条件下的结构转变得到了饱和的砷钨酸盐K3H3[As2W21O69(H2O)]·19H2O(1),借助傅立叶变换红外光谱和X射线单晶衍射对其结构进行了表征.结果表明,化合物1的多阴离子骨架由两个相同的三缺位[α-AsW9O33]9-片段通过三个W=O基团连接而成.值得提及的是,在化合物1的阴离子骨架中心空腔中存在一个游离的水分子.     

CF4 decomposition over solid ternary mixture NaF-Si-MO（MO=La2O3,CeO2,Pr6O-（11）,Nd2O3,Y2O3）

A solid ternary mixture consisting of NaF,silicon and one metal oxide such as La2O3,CeO2,Pr6O11,Nd2O3,and Y2O3 was prepared and usedas de-fluorinated reagent for CF4 decomposition.The results show that 90% conversion of CF4 can be reached initially over NaF-Si-La2O3,NaF-Si-CeO2,NaF-Si-Nd2O3,and NaF-Si-Y2O3 at 850 C.The fresh and used reagents were characterized using XRD and XPS techniques.It was found that the active components of NaF and metal oxides in NaF-Si-CeO2,NaF-Si-Pr6O11,NaF-Si-Nd2O3,and NaF-Si-Y2O3 weretransformed into inert phases of mixed metal fluorides and silicates,respectively,resulting in an ineffective utilization of these de-fluorinatedreagents,whereas no inert phases from NaF and La2O3 can be observed in the used NaF-Si-La2O3,indicating the NaF-Si-La2O3 reagent couldbe utilized more efficiently than the other reagents in CF4 decomposition.     

Mg掺杂In2O3-x催化剂光热催化CO2加氢

为提高光热催化CO₂加氢In₂O₃催化剂的催化活性,采用均相水热法制备Mg (OH)₂-In (OH)₃前驱体,通过高温煅烧和H₂-还原处理得到了富含氧空位的Mg掺杂In₂O_3-x(Mg-In₂O_3-x)催化剂。在300℃、常压、可见光照射条件下,CO₂加氢转化为CO的CO₂转化率可达31.20%,CO产生速率为14.22 mmol·g_cat^-1·h^-1,CO选择性为100%。相比于单一In₂O_3-x催化剂,Mg-In₂O_3-x催化剂光热催化CO₂转化率及CO产生速率明显提高,这归因于Mg成功掺杂到In₂O₃晶格中,促进In₂O₃表面氧空位的形成,进而对可见光响应效率大幅提高,并有效减缓光生电子-空穴的复合。     

Mg掺杂In2O3-x催化剂光热催化CO2加氢

为提高光热催化CO₂加氢催化剂In₂O₃的催化活性,采用均相水热法制备Mg(OH)₂-In(OH)₃前驱体,通过高温煅烧和H₂-还原处理得到了富含氧空位的Mg掺杂In₂O_3-x(Mg-In₂O_3-x)催化剂。在300℃、常压、可见光照射条件下,CO₂加氢转化为CO的CO₂转化率可达31.20%,CO产生速率为14.22 mmol·gcat^-1·h^-1,CO选择性为100%。相比于单一In₂O_3-x催化剂,Mg-In₂O_3-x催化剂光热催化CO₂转化率及CO产生速率明显提高,这归因于Mg成功掺杂到In₂O₃形晶格中,促进In₂O₃表面氧空位的形成,进而对可见光响应效率大幅提高,并有效减缓光生电子-空穴的复合。     

无氨湿法制备纳米晶In2O3及表征

Preparation of In₂O₃nano-scale powders by ultrasonic and homogeneous precipitation, using metal In and urea as raw materials, was reported for the first time, while the effects of reaction temperature, the ratio of the materials and the pH etc. on the preparation was dicussed. This method can be operated and industrialized easily with very low cost． The structural properties of precursor and In₂O₃were characterized by TG-DTA, XRD, ESCA and TEM. The results show that In₂O₃produced are very pure, monophase and spherical nano-scale powders with average size of 25 nm.     

B2O3对Ag/TiO2-Al2O3吸附剂的柴油吸附脱硫性能影响

采用浸渍法制备了不同B₂O₃负载量(e.g. 5%~20% (w))的Ag/TiO₂-B₂O₃-Al₂O₃吸附剂。以含硫量为245.36mg(S)/L 的商业柴油作为考察对象,常温常压下采用静态评价进行吸附脱硫性能研究。结果表明,B₂O₃改性后的Ag/TiO₂-Al₂O₃吸附剂的柴油吸附脱硫活性有了较大提高,当B₂O₃的负载量为15%时,吸附剂的吸附脱硫活性最高,2%Ag/4%TiO₂-15%B₂O₃-Al₂O₃ (w)的饱和吸附硫容达到2.36mg(S)/g 吸附剂。这对于未经预处理的商业柴油而言,吸附脱硫活性已经达到较高水平。采用N₂物理吸附、O₂化学吸附、X射线衍射(XRD)、NH₃程序升温脱附(NH₃-TPD)、傅里叶红外光谱(FT-IR spectra)、¹¹B核磁共振(¹¹B-NMR)等表征手段对不同负载量B₂O₃改性Ag/TiO₂-Al₂O₃吸附剂的织构性质、晶相结构和表面酸性的影响进行研究。关联活性测试和表征结果发现,吸附剂的吸附脱硫活性主要与吸附剂的表面弱酸性有关,而B₂O₃改性在吸附剂表面引入了较多的四配位的BO₄物种,能显著增加吸附剂表面弱酸性位点数量,提高吸附剂的吸附脱硫活性。     

Reaction of tetrahydrofuran with H2S in the presence of Na+/γ-Al2O3

Modification of -Al₂O₃ by sodium hydroxide promotes the increase of surface basicity but does not exert a strong effect on catalytic activity in the reaction of thiolane production from tetrahydrofuran and H₂S. Introduction of NaOH to -Al₂O₃ in small concentration increases the number of Lewis acid centers but decreases their strength. The activity of Na/-Al₂O₃ referred to one Lewis acid center drops.     

Layered manganese 4-phosphonoisophthalates （4-piH4） embedding Mn-O chains with metamagnetism in Mn3（4-piH）2（H2O）3·H2O

Two manganese phosphonates Mn3(4-piH)2(H2O)3·H2O (1) and Mn5(4-piH)2(4-piH2)2(phen)2(H2O)4 (2) (4-piH4 = 4-phosphonoisophthalic acid, phen = 1,10-phenanthroline) have been synthesized under hydrothermal conditions in the presence of organic co-ligand. Both compounds exhibit layer structures but with different topologies. In compound 1, a complicated "ladder-like" chain of {Mn3O3}O2 which contains three- and six-member rings made up of triangular shaped {Mn3O3} trimers is found. The chains are linked by the PO3C groups to form an inorganic layer. The phenyl and protonated carboxylate groups are pendent between the layers with extensive hydrogen bonds. In compound 2, tetramers of {Mn4O6} are connected by the {MnO6} octahedra through corner-sharing to form an infinite chain, which is further bridged by 4-piH3- ligands into a thick hybrid layer. Magnetic measurements reveal that antiferromagnetic interactions are dominant in both compounds. Metamag- netism is observed in compound 1 at low temperature, while no long range ordering is found in compound 2 down to 1.8 K.     

Nanocrystalline In2O3-based H2S sensors operable at low temperatures

Nanocrystalline In(2)O(3)-based solid solutions, with different concentration of Co, with cubic structure were successfully prepared by a simple route. The as-prepared materials were characterized by X-ray diffraction (XRD) and transmission electron microscopy (TEM). The indirect heating structure sensors based on pure and doped In(2)O(3) as sensitive materials were fabricated on an alumna tube with Au electrodes and gas-sensing properties of the sensor elements were measured as a function of concentration of dopant, operating temperature and concentrations of the test gases. The results showed that In(2)O(3) had high response towards H(2)S gas at an operating temperature 150 degrees C, while 2.5 wt.% Co-doped In(2)O(3) sensor exhibited enhance response and selectivity to H(2)S at rather lower operating temperature. Incorporation of platinum further improved the response, selectivity and response time towards H(2)S. Platinum incorporated 2.5 wt.% Co-doped In(2)O(3) (Pt: 0.5 wt.%) was able to detect 10-100 ppm of H(2)S in air at an operating temperature of 100 degrees C. The selectivity of the sensor elements for H(2)S against liquefied petroleum gas (LPG), NH(3) and H(2) gases was studied. The improved gas-sensing properties can mainly be attributed to the selectivity to oxidation of H(2)S and noble metal additive sensitization.     

Novel ZnO-Al2O3 composite particles as sorbent for low temperature H2S removal

ZnO-Al₂O₃ composite particles composed of ZnO nanosheets（thickness of 40-80 nm） on alumina particles were prepared by heterogeneous precipitation method using bayerite seed particles.The asprepared composite particles were characterized in terms of crystal structure,morphology,surface area and pore volume.The composite particles were used as sorbent for H₂S adsorption at low temperature, and were compared with pure ZnO sorbent.The composite sorbent showed a greater sulfur adsorption capacity（0.052 g/g） than pure form of ZnO（0.028 g/g）.This significant improvement was mainly attributed to higher surface area,more pore volume and unique morphology in nanoscale,which were also obtained by low cost presented method in this work for synthesis of ZnO sorbent supported on alumina particles.     

Two Related Porous Thioindates with T3 Clusters, (H2DAH)3In10S18·6H2O and (H2DAH)3In10S18

Two high porous thioindates with 1,6‐diaminohexane (DAH), DAH‐InS‐ 1 and DAH‐InS‐ 2 , were prepared by solvothermal reaction. Though the same T₃ supertetrahedral frameworks were reported, the cations are different. DAH is a non‐cyclic diamine and also an economical reagent for synthesis. Because of the structural difference of the structural directing agents, the dimensions of crystal cells of DAH‐InS‐ 1 and DAH‐InS‐ 2 are elongated and the total volumes for the cation and solvent are 74.6 and 72.1 % (Platon) larger relative to those reported previously. The two compounds were obtained in one reaction system by controlling the reaction time. Their structures are briefly discussed and the correlativity of crystal shape with the parameters of microstructure is discussed.     

The kinetics of the B2H6/O (3P) system at room temperature

An experimental study of the kinetics of the B₂H₆/O (³P) system at room temperature, is presented. Modeling was based on a multiple-parameter fitting process to a complex kinetic mechanism. The aim of the study was to propose and evaluate a preferred set of elementary reactions which might be important for the oxidation of boron-hydrides. In this study, relative concentration-vs.-time profiles of the radicals OH and BO₂ were measured in a low pressure flow reactor, by the technique of laser-induced-fluorescence. A range of almost two orders of magnitude in the initial fuel to oxygen ratio was covered, while the residence times of the gases in the reactor were up to 1 s. A comprehensive kinetic mechanism was constructed from the available measured and estimated data in literature. After the fitting process and dropping all of the reactions with negligible contribution, a 46 elementary reactions mechanism was obtained. In this mechanism, 27 reactions are not measured and their rate coefficients were used as the adjustable (within reasonable limits deduced from kinetic and thermodynamic considerations) parameters of the fitting process. Good agreement was obtained between all of the measured and calculated profiles. From sensitivity analysis it was found that only a limited group of these reactions highly contributes to the calculated concentrations of OH and BO₂. With only the highly contributing reactions and all the oxygenhydrogen reactions which are measured and relatively well known, a 30 elementary reactions mechanism was obtained. In this mechanism only 13 reactions are not measured and the agreement between the measured and the calculated profiles is still reasonable. To demonstrate the possible usefulness of the proposed mechanism, the rate coefficient of the reaction B₂H₆ + OH → B₂H₅ + H₂O which was not measured before, was directly measured in our experimental set-up. The rate coefficient that was obtained in the direct measurement is (3.3 ± 1.1) × 10¹¹ cm³mol^?1s^?1, in excellent agreement with the predicted one by the multiple-parameter-fitting process, which was 2 × 10¹¹ cm³mol^?1s^?1. © 1995 John Wiley & Sons, Inc.     

Optical constants of HNO3/H2O and H2SO4/HNO3/H2O at low temperatures in the infrared region

The complex index of refraction of liquid HNO3/H2O and H2SO4/HNO3/H2O has been obtained at different temperatures and acid concentrations. FT-IR specular reflectance spectra were obtained for 30, 54, and 64 wt % aqueous HNO3 and for four different H2SO4/HNO3/H2O mixtures in the temperature region from 293 to 183 K. The complex index of refraction was obtained from the reflectance spectra with the Kramers-Kronig transformation. The optical constants of the binary and ternary mixtures vary with the acid concentration and the temperature. The results demonstrate that vibrational bands originating from the sulfate species are more sensitive to changes in temperature than the bands originating from vibrations in the nitrate species; only minor changes in the nitrate vibrational bands are observed as the temperature decreases below 248 K.     

Crystal Structure and Thermal Stability of Ag3(CHF2COO)3(H2O)2

X-ray diffraction analysis of [Ag₃(CHF₂COO)₃(H₂O)₂] revealed that its crystals are orthorhombic: space group Cmca, a = 13.809(4) Å, b = 15.975(2) Å, c = 12.244(2) Å, Z = 8. The thermogravimetric analysis showed that under the atmosphere of N₂ and at 101.3 kPa, silver difluoroacetate melts at 488 K; the thermal decomposition reaction occurs in the interval 493–548 K with the formation of Ag. Under the mass-spectral experiment conditions at 521 K, two processes occur simultaneously, namely, evaporation and decomposition. The following ions were detected in the mass-spectrum of silver difluoroacetate: Ag₂L⁺, Ag₂R⁺, Ag₂F⁺, Ag₂O⁺, Ag₂ ⁺, Ag⁺, LH⁺, RCO⁺, R⁺ (L = CHF₂COO, R = CHF₂).     

Flexible 3D porous metal-organic framework exhibiting selective adsorption for H2O over organic solvents

A new flexible 3D porous metal-organic framework (MOF) with 1D open nanotube,[Co2(μ5-CTAI)(dpe)(H2O)2]n·6n(H2O)(1) (CTA=cyclohexane-1,2,4,5-tetracarboxylic acid,dpe=1,2-di(4-pyridyl) ethylene) has been prepared and structurally characterized.Meanwhile,each 1D nanotubes filled with 1D water chain with dimension of 13.711 × 12.275 2.Compound 1 represents a new example that collapse/deform upon dehydration/hydration and shows adsorb H 2 O selectively over organic solvents.     

Argon adsorption on Cu3(benzene-1,3,5-tricarboxylate)2(H2O)3 metal-organic framework

Using volumetric adsorption techniques, we have measured the adsorption of argon on Cu3(BTC)2(H2O)3, (BTC = benzene-1,3,5-tricarboxylate), a microporous metal-organic framework structure, at temperatures between 66 and 143 K. In addition to the experiments, we have used Grand Canonical Monte Carlo simulations to calculate the adsorption isotherm of argon at 87 K. Our experimental and theoretical results are compared to those of previous studies. The experiments were performed using a high density of points, allowing us to obtain, in detail, the isosteric heat's coverage dependence. Our values from the simulations are in reasonable agreement with those obtained in the experiments.