KIT-1介孔分子筛的化学修饰及吸附性能

介孔分子筛MCM-41具有较大、可调的孔径和较高的比表面积，其骨架组成具有较强的可调变性．为该材料的应用提供了很大的空间。但全硅MCM-41分子筛在潮湿空气中，即使在室温条件下也会发生水解反应，使其介孔结构遭到破坏。前人已针对MCM-41分子筛稳定性不足的问题相继合成了稳定性较高的介孔分子筛KIT-1,     

Continuous pH monitoring during pretreatment of yellow poplar wood sawdust by pressure cooking in water

Yellow poplar wood sawdust consists of 41% cellulose and 19% hemicellulose. The goal of pressure cooking this material in water is to hydrate the more chemically resistive regions of cellulose in order to enhance enzymatic conversion to glucose. Pretreatment can generate organic acids through acid-catalyzed degradation of monosaccharides formed because of acids released from the biomass material or the inherent acidity of the water at temperatures above 160°C. The resulting acids will further promote the acid-catalyzed degradation of monomers that cause both a reduction in the yield and the formation of fermentation inhibitors such as hydroxymethyl furfural and furfural. A continuous pH-monitoring system was developed to help characterize the trends in pH during pretreatment and to assist in the development of a base (2.0 M KOH) addition profile to help keep the pH within a specified range in order to reduce any catalytic degradation and the formation of any monosac-charide degradation products during pretreatment. The results of this work are discussed.     

水热改性对NiMo/γ-Al2O3加氢脱氮催化剂结构及性能的影响

The influence of hydrothermal modification on the structure and hydrodenitrogenation (HDN) activity of NiMo/γ-Al₂O₃catalyst was studied in the range 140～180 ℃. The experimental results indicated that the hydrodenitrogenation reaction rate of pyridine was accelerated using the NiMo/γ-Al₂O₃catalyst synthesized via hydrothermal route due to the change of the structure, the increase of the amount of Mo and Ni and the rise of the specific surface area. The change of the structure of catalysts was enhanced at higher hydrothermal temperature, producing NiMo/γ-Al₂O₃catalyst with better HDN activity.     

Influence of preparation conditions on thermal properties of lanthanide benzenepolycarboxylates

Properties of lanthanide 1,2,4-benzenetricarboxylates and lanthanide 1,2,4,5-benzenetetracarboxylates obtained by a classical synthesis method and under hydrothermal conditions were compared. Solid 1,2,4-benzenetricarboxylates and 1,2,4,5-benzenetetracarboxylates of cerium, neodymium and erbium were prepared by a classical precipitation method. The same lanthanide compounds were obtained also from hydrothermal reaction. All obtained products were examined by elemental analysis. General formulae of complexes were: Ln(1,2,4-btc)·xH₂O and Ln₄(1,2,4,5-btec)₃·yH₂O. The thermal analysis shows that hydrothermal conditions cause the coordination of less number of water molecules to complex molecule. Because lanthanide ions exhibit the most often the coordination number equal 8 or 9 one can conclude that the coordination ability of carboxylic groups under hydrothermal conditions is different from that under mild ones. Probably, in hydrothermal conditions the carboxylic groups of 1,2,4-benzenetricarboxylate ions are able to form more coordination bonds with lanthanide ions than under normal pressure.     

One Novel Vanadium-Phosphate Cluster [PV_(2.5)O_(8.5)]-3.83{H_2O} with Three-Dimensional Architecture

A novel vanadium-phosphate compound [PV_2.5O_8.5]·3.83{H_2O}(1)was obtained from the hydrothermal reac-tion and structurally characterized by elemental analysis and single-crystal X-ray diffraction,which exhibited thatthe title complex crystallized in cubic space group I-43m with crystal data:a=1.6115(1)nm,V=4.1848(1)nm~3,Z=12,D_c=1.783 g/cm~3,F(000)=2278,R_1=0.0528,and wR_2=0.1329[I>2σ(I)](all data).The basic unit of{PV_2.5O_8.5}symmetrically extended to closed sphere-like structure of{P_4V_(10)O_(34)},which was further linked to in-terleaving three-dimensional network via sharing four phosphate through μ_3-oxygen atoms around the closedsphere-like structures.     

溶剂热/水热条件下空旷结构草酸锌的合成

应用水热法及溶剂热方法，选择两种模板剂1，2-丙二胺和4，5-二氮芴-9-酮连氮(L)设计合成了草酸锌空旷结构材料[Zn₂(C₂O₄)3][C₃H₁₂N₂]·H₂O (Ⅰ)和[Zn₂(C₂O₄)₃]·L·6[H₃O] (Ⅱ)，使用CHN元素分析、     

Synthesis, nuclear, and magnetic structures and magnetic properties of [Mn3(OH)2(SO4)2(H2O)2

[Mn(3)(OH)(2)(SO(4))(2)(H(2)O)(2)] and its deuterated analogue were synthesized by a hydrothermal technique and characterized by differential thermal analysis, thermogravimetric analysis, and IR spectroscopy. Its nuclear structure, determined by single-crystal X-ray analysis and Rietveld analysis of neutron powder-diffraction data, consists of a 3D network of chains of edge-sharing Mn(1)O(6), running along the c axis, connected by the apices of Mn(2)O(6) and SO(4) units. It is isostructural to the nickel analogue. Determination of the magnetic structure and measurements of magnetization and heat capacity indicate the coexistence of both magnetic long-range ordering (LRO) and short-range ordering (SRO) below a Néel temperature of 26 K, while the SRO is retained at higher temperatures. The moments of the two independent Mn atoms lie in the bc plane, and that of Mn(1) rotates continuously by 54 degrees towards the c axis on decreasing the temperature from 25 to 1.4 K. While the SRO may be associated with frustration of the moments within a Mn(3) trimer, the LRO is achieved by antiparallel alignment of the four symmetry-related trimers within the magnetic unit cell. A spin-flop field, measured by dc and ac magnetization on a SQUID, is observed at 15 kOe.     

Hydrothermal Synthesis and Structure Characterization of a Novel 4,4′-Bipyridine Bridging Dumbbell-like Dimeric Pentamolybdate

1 INTRODUCTION Polyoxometalates (POMs) have been attracting extensive interest of many chemists in solid-state materials chemistry owning to the various structures and great potential applications in catalysis, medi- cine, photo-electricity and magnetism[1～9]. Over the past decades, lots of novel POMs have been pre- pared by hydrothermal synthesis, such as discrete structure[10], one-dimensional chain-like structure[11, 12] and higher dimensional architecture[13～18]. However, in these…     

Synthesis and Crystal Structure of Mixed-Ligand Ni(II) Complex of N-(1-Phenyl-3-methyl-4-benzylidene-5-pyrazolone) p-Nitrobezoylhydrazide and Pyridine

A novel mixed-ligand nickel complex, [Ni(PMBP—PNH) (Py)₃], [PMBP—PNH=N-(1-phenyl-3-methyl-4-benzylidene-5-pyrazolone) p-nitrobezoylhydrazide; Py = pyridine], has been synthesized by the hydrothermal method and characterized by elemental analysis, IR spectrum, thermal analysis, and single-crystal X-ray diffraction. The X-ray diffraction reveals that the nickel (II) ion in the title complex is in a slightly distorted octahedral arrangement of the ONO donor atoms of primary ligand PMBP-PNH and three N-donor atoms in the secondary ligand pyridine.     

水热法制备高纯超细CeO2-ZrO2复合氧化物

Superfine composite powders of CeO₂-ZrO₂ (CZ) and CeO₂-ZrO₂-La₂O₃ (CZL) were prepared by hydrothermal method. The effects of pH、temperature and time for hydrothermal process on the performance of the resulting powders were studied. The optimized reaction parameters were on follows: the precursor′s pH≈9.0, hydrothermal temperature of 200 ℃ holding for 2 h. Thermal stable powders with average particle size smaller than 10 nm and specific surface area of 171 m²·g^-1 were obtained. A BET specific surface area was still at 44 m²·g^-1 after calcination at 1 000 ℃ for 6 hours.