ZSM-11 zeolite is tetragonal, with a two-dimensional pore structure, is an important shape-selective adsorbent and catalyst for good. ZSM-5 zeolite with the same family are Pentasil, because with the structure of zeolite ZSM-5 is very similar, so the synthesis of ZSM-11 zeolite in the process is prone to ZSM-11/ZSM-5 eutectic growth phenomenon . Therefore, high purity synthetic zeolite ZSM-11 has long been the problem of many researchers. The past is mainly used tetrabutylammonium bromide or tetrabutylammonium hydroxide as templating agent in the hydrothermal synthesis of ZSM-11 system, zeolite, on the basis of this the first time in the previous four-phenyl-butyl ammonium bromide and the top three ammonium chloride as a template to synthesize a common high-purity ZSM-11 zeolite. And focus from the alkalinity, template, water content, crystallization time and crystallization temperature, and several other areas examined in detail the various factors on the crystallization process and the impact of synthetic samples. By examining the two kinds of template for the synthesis of zeolite, and found that tetrabutyl ammonium bromide or tetrabutyl ammonium hydroxide in the synthesis of ZSM-11 zeolite structure plays an important role in guiding, and phenyl trimethyl ammonium chloride presence is very necessary, plays to promote the synthesis of ZSM-11 zeolite purer, more well-crystallized role. In situ solid-phase inversion method to overcome the hot water system and some of the shortcomings of non-water system has to improve product quality, reduce cost, environmentally friendly advantages, synthetic zeolite is an ideal method. Therefore, this article hydrothermal method based on the phase inversion method using in situ solid-phase synthesis of pure ZSM-11 zeolite was investigated in the synthesis of the impact of various factors on the product, and with the conventional hydrothermal wears comparison . The results show that in situ conversion of solid phase crystallization method can also be synthesized zeolite sample well. This system of water content in small, H_2O/SiO_2 minimum to 3 can still be a good synthesis of crystalline zeolite ZSM-11; in the case of absolute water, after numerous experiments have been amorphous product, indicating that water Solid-phase system in the heat and mass transfer plays a necessary role. In the solid-phase synthesis system, mineralizer NaF crystal nucleation played a role in the promotion, making synthesis of pure phase ZSM-11 zeolite easier. The development of hetero-atom zeolite molecular sieve synthesis and catalysis has great role in promoting, is one of the hot research in recent years, due to the introduction of a skeleton with a high catalytic activity of the hetero-atom, the zeolite has a special The catalytic properties; or modified by the modulation of these heteroatom zeolite catalyst can have a variety of functions, is a good composite catalytic materials. Therefore, growing attention in recent years heteroatom zeolite synthesis and application development. Impurity atoms in ZSM-11 zeolite is also the focus of attention. Therefore, the issue in the synthesis of pure silica ZSM-11 zeolite doped with boron atoms on the basis of further obtain pure phase, high crystallinity of B-ZSM-11 zeolite. Examined the boron atom of the zeolite synthesis process and products, and through a variety of characterization that boron atoms into the zeolite framework. The results show that synthetic B-ZSM-11 zeolite, the ratio of raw materials in the range of Na_2O/SiO_2 than pure silicon than the synthetic zeolite ZSM-11 should be wide, and with the incorporation of boron increases, alkalinity be increased gradually. At the same time, using in situ solid-phase synthesis of doped B-ZSM-11 zeolite, compared the two systems and the synthesis of pure silica samples of zeolite ZSM-11 the similarities and differences found in B-ZSM-11 zeolite crystal cell parameters significantly less than pure silicon ZSM-11 zeolite, and the in situ solid-phase synthesis of B-ZSM-11 zeolite lattice parameters slightly larger than hydrothermal synthesis of zeolite samples. Nano-zeolite has a larger surface area, high surface energy, short-channel, etc., will help accelerate the catalytic reaction and adsorption heat and mass transfer process, thus improving catalyst utilization, enhanced reactivity and selectivity of the catalyst, extend the response operation cycle, to improve selectivity and reduce the coke deactivation, etc. have shown superior performance. Therefore, this article in the synthesis of conventional micron-ZSM-11 zeolite, based on the ratio of raw materials and by adjusting the crystallization conditions for the further synthesis of a 10nm particle size can be controlled in the suspended state within the zeolite ZSM-11 and B-ZSM- 11 zeolite, and examine the ratio of reactants and crystallization time on the synthesis of zeolite particle size, crystallinity and surface area of impact. The results show that adding alkali and ethanol can effectively reduce the crystal particle size, to extend the crystallization time can significantly increase the grain size.
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Thursday, December 1, 2011
Wednesday, November 30, 2011
What is graphite oxide
graphite oxide is a compound of carbon , oxygen and hydrogen in varying proportions by graphite obtained with strong oxidizing agents. The bulk material is oxidized to a yellow solid with a C: O 2.1 to 2.9 , which retains the layered structure of graphite , but with a distance much larger and irregular.
the color of graphite oxide remains yellow, water-soluble is very good, no precipitation. Content of dissolved more than 99% single, micro-chip the size of 1 to 5 microns, the thickness of about 0.8 to 1.2 nm. This product has many advantages:1. preparation of clear, mature technology, easy to write articles for scientific research;2. good water solubility, sheet size, uniform, controllable;3. no Suixiao particles, high-temperature graphene oxide powder prepared by small particles and more layers curl is not conducive to experiments carried out.
With hydrazine hydrate suspension to reduce some of the graphite oxide 100 ° C, 24 hours , or by hydrogen peroxide plasma map some of the second action , [ 15 ] or pulsed xenon flash light is strong . [ 18 ] However , this approach will be less than 10 S / cm conductivity curve [ 18 ] and charge from a 200 cm2 / (V · S) orifice , from .5 to 30 cm2 / (V · S) for the electrons. These height values as oxides , but there are smaller scale than the original graph several orders of magnitude lower . Atomic force microscopy showed that the carbon – oxygen layer is distorted , it ‘s a significant business within the oxide layer thickness of the rough , reduced after . These errors occurred in the Raman spectra of graphene .
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the color of graphite oxide remains yellow, water-soluble is very good, no precipitation. Content of dissolved more than 99% single, micro-chip the size of 1 to 5 microns, the thickness of about 0.8 to 1.2 nm. This product has many advantages:1. preparation of clear, mature technology, easy to write articles for scientific research;2. good water solubility, sheet size, uniform, controllable;3. no Suixiao particles, high-temperature graphene oxide powder prepared by small particles and more layers curl is not conducive to experiments carried out.
With hydrazine hydrate suspension to reduce some of the graphite oxide 100 ° C, 24 hours , or by hydrogen peroxide plasma map some of the second action , [ 15 ] or pulsed xenon flash light is strong . [ 18 ] However , this approach will be less than 10 S / cm conductivity curve [ 18 ] and charge from a 200 cm2 / (V · S) orifice , from .5 to 30 cm2 / (V · S) for the electrons. These height values as oxides , but there are smaller scale than the original graph several orders of magnitude lower . Atomic force microscopy showed that the carbon – oxygen layer is distorted , it ‘s a significant business within the oxide layer thickness of the rough , reduced after . These errors occurred in the Raman spectra of graphene .
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Tuesday, November 29, 2011
The Introduction of carboxyl graphene powder
Carboxyl graphene powder is yellow powder, soluble in water, 5% carboxyl content, carboxyl parameters have been out of the products, product performance is very good.
1) Since graphene has a very high specific surface area, leading to its reunion is very serious, difficult to disperse polar or non polar solvents.
We are completely solve the problem of dispersion of graphene, its application in composite materials cleared the way;
2) graphene oxide is graphene-modified intermediates, we have been carboxylated graphene surface carboxyl content of 5.0 wt.% Or so, greatly conducive to the next step of the application;
3) available in volume quantities of graphene oxide film (paper) and graphite film (paper);
4) can be ordered graphene or graphene oxide dispersion (polar or non polar solvents may be);
5) and the American elite to launch high-end modified graphene - amination of graphene and graphene-based thiol。
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1) Since graphene has a very high specific surface area, leading to its reunion is very serious, difficult to disperse polar or non polar solvents.
We are completely solve the problem of dispersion of graphene, its application in composite materials cleared the way;
2) graphene oxide is graphene-modified intermediates, we have been carboxylated graphene surface carboxyl content of 5.0 wt.% Or so, greatly conducive to the next step of the application;
3) available in volume quantities of graphene oxide film (paper) and graphite film (paper);
4) can be ordered graphene or graphene oxide dispersion (polar or non polar solvents may be);
5) and the American elite to launch high-end modified graphene - amination of graphene and graphene-based thiol。
Read more: carboxyl graphene powder for sale
Monday, November 28, 2011
The Introduction of CMK-3
CMK-3 over the CAC, adsorption capacity, adsorption rate, and equilibrium time is short, is a good adsorbent, while of the mesoporous carbon CMK-3 for phenol adsorption thermodynamics and kinetics. CMK-3 adsorption of phenol used Langmuir and Freundlich isotherm to describe the correlation is good, but more in line with Freundlich empirical formula. were used to simulate first-order reaction and second-order reaction model examined the adsorption kinetics and the calculation of these dynamics model rate constants. analog second-order reaction model and experimental data a good correlation between the respectively calculated thermodynamic parameters ΔG0, ΔS0 and ΔH0, results show that, CMK-3 for phenol adsorption process is endothermic and spontaneous .
Mesoporous carbon is a new type of non-silicon-based mesoporous materials with large specific surface area (up to 2500m2 / g) and pore volume (up to 2.25cm3 / g), is expected to catalyst, hydrogen storage materials, electrode materials and other aspects of important applications, so are people’s attention. In addition, mesoporous materials obtained by the double-layer capacitance charge storage material above the metal oxide particles assembled electric capacity, far higher than commercially available metal oxide double-layer capacitors.
And pure mesoporous silica materials, mesoporous carbon materials exhibit unique properties, high specific surface area, high porosity; pore size adjustable within a certain range; mesoporous shapes, hole wall composition, structure and nature of the adjustable; by optimizing the synthesis conditions can be high thermal stability and hydrothermal stability; synthesis is simple, easy to operate, no physiological toxicity. It is still in its attraction of fuel cells, molecular sieve, adsorption, catalysis, electrochemistry and other areas of potential applications. In recent years, mesoporous materials science has become an international cross-chemistry, physics, materials, biology and other disciplines cross one of the hot areas of research, development of materials science have become an important milestone.
Mesoporous material as a photocatalyst for the treatment of environmental contaminants is one of the hot research in recent years. For example, mesoporous TiO2 Bi Nami TiO2 (P25) has a higher photocatalytic activity, because the mesoporous structure with high surface area to improve contact with organic molecules, an increase of surface adsorbed water and hydroxyl, water and hydroxyl groups with the catalyst surface can be excited by light the reaction of hydroxyl radical hole, and hydroxyl radical degradation of organic matter is a strong oxidant, can put a lot of biodegradable organic matter is oxidized to CO2 and water and other minerals. In addition, the ordered mesoporous materials for selective doping can improve the optical activity of visible light photocatalytic degradation of organic waste to increase the efficiency.
Now widely used in domestic water chlorine disinfection process though killed all bacteria, but had chloroform, carbon tetrachloride, monochloroacetic acid and a series of toxic organic compounds, its serious “three letter” effects (cancer, teratogenic, mutagenic) has attracted international scientific and medical community’s attention. Through the pores of mesoporous materials received on the inner wall of the school γ-chloropropyl triethoxysilane, has been functionalized mesoporous CPS-HMS, the functional mesoporous molecular sieves to remove traces of chloroform in water results are obvious, the removal rate of up to 97%. After the treated water chloroform concentrations below the national standard, even lower than the drinking water standards.
Read more: CMK-3 for sale
Mesoporous carbon is a new type of non-silicon-based mesoporous materials with large specific surface area (up to 2500m2 / g) and pore volume (up to 2.25cm3 / g), is expected to catalyst, hydrogen storage materials, electrode materials and other aspects of important applications, so are people’s attention. In addition, mesoporous materials obtained by the double-layer capacitance charge storage material above the metal oxide particles assembled electric capacity, far higher than commercially available metal oxide double-layer capacitors.
And pure mesoporous silica materials, mesoporous carbon materials exhibit unique properties, high specific surface area, high porosity; pore size adjustable within a certain range; mesoporous shapes, hole wall composition, structure and nature of the adjustable; by optimizing the synthesis conditions can be high thermal stability and hydrothermal stability; synthesis is simple, easy to operate, no physiological toxicity. It is still in its attraction of fuel cells, molecular sieve, adsorption, catalysis, electrochemistry and other areas of potential applications. In recent years, mesoporous materials science has become an international cross-chemistry, physics, materials, biology and other disciplines cross one of the hot areas of research, development of materials science have become an important milestone.
Mesoporous material as a photocatalyst for the treatment of environmental contaminants is one of the hot research in recent years. For example, mesoporous TiO2 Bi Nami TiO2 (P25) has a higher photocatalytic activity, because the mesoporous structure with high surface area to improve contact with organic molecules, an increase of surface adsorbed water and hydroxyl, water and hydroxyl groups with the catalyst surface can be excited by light the reaction of hydroxyl radical hole, and hydroxyl radical degradation of organic matter is a strong oxidant, can put a lot of biodegradable organic matter is oxidized to CO2 and water and other minerals. In addition, the ordered mesoporous materials for selective doping can improve the optical activity of visible light photocatalytic degradation of organic waste to increase the efficiency.
Now widely used in domestic water chlorine disinfection process though killed all bacteria, but had chloroform, carbon tetrachloride, monochloroacetic acid and a series of toxic organic compounds, its serious “three letter” effects (cancer, teratogenic, mutagenic) has attracted international scientific and medical community’s attention. Through the pores of mesoporous materials received on the inner wall of the school γ-chloropropyl triethoxysilane, has been functionalized mesoporous CPS-HMS, the functional mesoporous molecular sieves to remove traces of chloroform in water results are obvious, the removal rate of up to 97%. After the treated water chloroform concentrations below the national standard, even lower than the drinking water standards.
Read more: CMK-3 for sale
Friday, November 25, 2011
The Introduction of MCM-41
A technique called MCM-41 of ordered mesoporous materials, it is a new type of nano structure material, has featured six party in orderly arrangement, size uniform, pore diameter can be in 2-10 nm range continuous adjustment, high spicific surface etc. Characteristics. MCM-and from the traditional synthesis Molecule sieve synthesis is the biggest characteristic of the template, different, traditional zeolite synthesis of molecular sieve Molecule or small organic Molecule in a single molecular or metal ion for template agent and ZSM-5 as an example, the typical template, for four propyl amine ion, crystal is through the acid salt in the template, around the formation of condensation. And the synthesis of MCM-41 is different, it is in large Molecule molecular surfactants as a template,, template, alkyl chain generally more than 10 carbon atom, about the formation of it has already proposed two mechanism, and continue to improve and perfect. Compared with other zeolite materials, MCM-41 skeleton aluminum species are relatively poor thermal stability, in the roasting process, aluminum frame by frame fall off as a species skeleton aluminum species.
Pure silicon MCM-41 itself acid is very weak, as catalytic activity directly is low. Therefore, researchers often the modification, to increase its catalytic activity.
Modification methods include：
(1) synthetic skeleton structure with miscellaneous atomic MCM-41, coordination of the four central skeleton ion such as: A13 +, Cu2 + +, and Zn2 Fe3, +, and Ga3 + from anions and surface center, but through the protons or other transition metal ions to compete so as to form the catalytic activity center.
(2) using in heteropoly acid etc are method, made a series of applicable to different reaction of multiphase catalysts, such as: B acid hydrogen type MCM-41; Doping L acid type MCM-1; Mixed metal oxide alkaline or sexual MCM-41; Bear in PW12, SIW12, such as the PMo12 MCM-41 heterpoly acid; And in SO42 / bear TiO2, ZrO2 / SO42- such as solid super acid type MCM-41.
(3) MCM-41 hole assembly solid in transition metal complex molecules.
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Pure silicon MCM-41 itself acid is very weak, as catalytic activity directly is low. Therefore, researchers often the modification, to increase its catalytic activity.
Modification methods include：
(1) synthetic skeleton structure with miscellaneous atomic MCM-41, coordination of the four central skeleton ion such as: A13 +, Cu2 + +, and Zn2 Fe3, +, and Ga3 + from anions and surface center, but through the protons or other transition metal ions to compete so as to form the catalytic activity center.
(2) using in heteropoly acid etc are method, made a series of applicable to different reaction of multiphase catalysts, such as: B acid hydrogen type MCM-41; Doping L acid type MCM-1; Mixed metal oxide alkaline or sexual MCM-41; Bear in PW12, SIW12, such as the PMo12 MCM-41 heterpoly acid; And in SO42 / bear TiO2, ZrO2 / SO42- such as solid super acid type MCM-41.
(3) MCM-41 hole assembly solid in transition metal complex molecules.
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Thursday, November 24, 2011
What is Graphene oxide powder
Graphene oxide powder formerly called graphite oxide, graphitic oxide or graphitic acid, is a compound of carbon, oxygen, and hydrogen in variable ratios, obtained by treating graphite with strong oxidizers.The maximally oxidized bulk product is yellow solid with C:O ratio between 2.1 and 2.9. It consists of loosely-bound layers, each being a two-dimensional arrangement of carbon atoms in the “chicken-wire” (graphene) pattern, with epoxide groups (bridging oxygen atoms) and hydroxyl groups attached to both sides.Graphene oxide has attracted much interest recently as a possible route for the large-scale production and manipulation of graphene, a material with extraordinary electronic properties. Graphene oxide itself is an insulator, almost a semiconductor, with differential conductivity between 1 and 5 x 10-3 S/cm at a bias voltage of 10 V. However, being hydrophilic, graphene oxide disperses readily in water, breaking up into macroscopic flakes, mostly one layer thick. In theory, chemical reduction of these flakes would yield a suspension of graphene flakes.
These values are much greater than the oxide’s, but still a few orders of magnitude lower than those of pristine graphene. Inspection with the atomic force microscope shows that the oxygen bonds distort the carbon layer, creating a pronounced intrinsic roughness in the oxide layers which persists after reduction. These defects also show up in Raman spectrum of graphene oxide.Reduction methods have been developed that do not use chemical solutions and can be performed at room temperature. a consumer camera flash has been shown to decompose graphene oxide to graphene.
Based on the graphite oxide aperture adjustable nano porous materials preparation methods, to natural flake graphite as raw material, strong sulfuric acid and sodium nitrate for intercalated agent and potassium permanganate as the oxidant of the thermal and chemical intercalated processing; Then will get flake graphite oxide to ion solution after the freeze-drying get flake graphite oxide powder, or use of polarity of the organic solvent to flake graphite oxide to ion solution for solvent for flake graphite oxide organic solvent suspension; , then use direct modification method and construct the supramolecular method of flake graphite oxide powder or flake graphite oxide organic solvent in modified suspension, get flake graphite oxide based on the pore diameter of adjustable nano porous materials; The party of the nano porous materials legal system through covalent bond or metal coordination key connection building, pore structure stability, the use of the modifying molecule range, can be in a wide range of adjust its pore size.
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These values are much greater than the oxide’s, but still a few orders of magnitude lower than those of pristine graphene. Inspection with the atomic force microscope shows that the oxygen bonds distort the carbon layer, creating a pronounced intrinsic roughness in the oxide layers which persists after reduction. These defects also show up in Raman spectrum of graphene oxide.Reduction methods have been developed that do not use chemical solutions and can be performed at room temperature. a consumer camera flash has been shown to decompose graphene oxide to graphene.
Based on the graphite oxide aperture adjustable nano porous materials preparation methods, to natural flake graphite as raw material, strong sulfuric acid and sodium nitrate for intercalated agent and potassium permanganate as the oxidant of the thermal and chemical intercalated processing; Then will get flake graphite oxide to ion solution after the freeze-drying get flake graphite oxide powder, or use of polarity of the organic solvent to flake graphite oxide to ion solution for solvent for flake graphite oxide organic solvent suspension; , then use direct modification method and construct the supramolecular method of flake graphite oxide powder or flake graphite oxide organic solvent in modified suspension, get flake graphite oxide based on the pore diameter of adjustable nano porous materials; The party of the nano porous materials legal system through covalent bond or metal coordination key connection building, pore structure stability, the use of the modifying molecule range, can be in a wide range of adjust its pore size.
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Wednesday, November 23, 2011
What is Graphene oxide paper
Graphene oxide paper or paper produced graphite oxide composite graphite oxide . The material has exceptional stiffness and strength , due to the inherent strength of the backbone and the two-dimensional graphene layer structure intertwined distributed load . Starting materials water-dispersed graphene oxide films, which often includes a graphene layer. Chemical bonding of these films may , leading to the development of additional new material . As raw materials , graphene oxide paper, is an electrical insulation ; However , you can transfer the property to make this conductor or semiconductor , and not at the expense of its mechanical properties. Detailed study of graphite oxide and p. There Kohlschutter later date can be traced back to 1918.
Researchers have developed a very simple way to convert ordinary graphite particles into very thin , but superstrong sheets, stronger than steel and carbon fiber as a flexible but more expensive . This finding will produce a new type of material and other industrial application of anti-corrosion coatings , electronic components , batteries, fuel cells .
Oxidation graphite papers can be system and solutions and phase alkyl modification, and the latter is clearly the process becomes slower. Gallery spacing, physical thickness and the quality of the thesis amine modification, increase physical adsorption removal amine, can directly interpolated alkyl chain length of related. Although after the modification of the paper tensile strength increases slightly amine length decreases, their “effective oxidation graphite modulus remain the same basic, suggesting that, graphite oxide is the only contribution to the stiffness of the modified paper amine.
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