803 results about "Layered double hydroxides" patented technology

The invention provides a corrosion-inhibiting anionic intercalated hydrotalcite/nano oxide composite material, a preparation method thereof and application of the corrosion-inhibiting anionic intercalated hydrotalcite/nano oxide composite material. The preparation method is as follows: corrosion-inhibiting anions are directly inserted between hydrotalcite layers by the one-step coprecipitation method and the roasting restoring method; the nano oxide is generated by means of in situ synchronization during the process of generation of hydrotalcite crystals by controlling the mixture ratio of divalent metal ions to trivalent metal ions, the pH value of a reaction solution and the reaction temperature; and the corrosion-inhibiting anionic intercalated hydrotalcite/nano oxide composite material with the anti-corrosive function is prepared. The invention is mainly characterized in that the in situ preparation method for the hydrotalcite/oxide composite material provided with a nano lamellar structure improves the release amount of a corrosion inhibitor and reduces the water absorption of a coating by leading into the corrosion inhibitor with the anti-corrosive function and the nano oxide which is generated in situ during the reaction process. The composite material can be used to be pigment of an anti-corrosive metallic coating system, and particularly has potential application value in improving the anti-corrosive performance of a magnesium alloy anti-corrosive coating.

The invention relates to a layered double hydroxide and a preparation method thereof, belonging to the technical field of metal hydroxide preparation. A chemical formula of the layered double hydroxide is as follows: (M1(1-x)M2x(OH)2)(A<n->)x/n), wherein x is larger than or equal to 0.2 and smaller than or equal to 0.33; M1 represents any one or more of divalent metal ions including Mg<2+>, Zn<2+>, Ni<2+>, Co<2+>, Ca<2+>, Cu<2+>, Fe<2+> and Mn<2+>; M2 represents any one or two of trivalent metal ions including Fe<3+> and Al<3+>; A<n-> represents any one of interlayer anions including CO3<2->,NO3<->, Cl<-> and SO4<2->; and the grain size ranges from 12 nm to 80 nm. The invention has the advantages that the preparation method is a direct method for preparing the layered double hydroxide with high crystallinity, layered structure regularity, wide application range and adjustable particle size. The preparation method comprises the following steps: obtaining highly dispersed metal nanoparticle sol by utilizing the action of colloid mill axial shear force and the sodium borohydride reducibility, and then performing slow oxydrolysis in a hydrothermal system, and the like to generate thenano layered double hydroxide with layered structure regularity and adjustable particle size. The method has the advantages of wide application range, low cost, simple operation and environmental protection.

The invention provides a supported bimetal nanocrystal catalyst which is a binary bimetal catalyst taking aluminum oxide as a supporter and is abbreviated to P-M/MgO-AlO3, wherein P represents noble metal such as Pd, Au, Pt, Ag and the like, and M represents one or two of metal cations such as Cu<2+>, Zn<2+>, Ni<2+>, Ga<3+> and Fe<3+>. The particle size of the P-M bimetal nanocrystal is 2-10 nm, the dimension distribution is narrow, the nanocrystal particles are highly dispersed on the surface of the supporter uniformly and stably, and the crystal form is complete. The preparation method of the catalyst comprises the following steps: preparing soluble Mg<2+> salt for MgMAl-LDH (layered double hydroxide) preparation and an endogenous active metal salt solution into a mixed solution; then simultaneously adding precipitant and the aluminum oxide supporter into the reaction system; enabling hydrotalcite to grow on the surface of the aluminum oxide supporter through an in-situ growth method; supporting exogenous active metal through a wet impregnation method; and performing high-temperature reduction on the obtained catalyst precursor under a reducing atmosphere, thus obtaining the supported bimetal nanocrystal catalyst which is stably and highly dispersed.

The invention relates to a method for preparing a minor-diameter carbon nanotube array on the surface of a flaky material, which belongs to the technical fields of nanometer materials and the preparation process thereof. The method comprises the following steps: the nanoparticles including one or more of Fe, Co, Ni, Cu and Mo (active metals) are dispersed on various flaky materials such as a graphitic sheet, magnesia or layered double hydroxide according to the density (10<8>-10<12> grains/cm<2>), then the chemical vapor deposition is performed, and finally, the carbon nanotube array grows onthe flaky surface. The diameter of the nanotube is less than 20 nm in the array. The method is easy to operate, realizes the mass production of the carbon nanotube array and promotes the industrial application.

The invention discloses a Ni-Mn layered double hydroxide@nickel foam@carbon three-dimensional hierarchically-structured electrode material and a preparation method thereof. The preparation method comprises the following steps: firstly carrying out one-step hydrothermal treatment by respectively taking nickel chloride hexahydrate, anhydrous manganese chloride and nickel foam as a nickel source, a manganese source and a substrate, so as to obtain Ni-Mn LDH@NF; and coating Ni-Mn LDH@NF by virtue of glucose or graphene as a carbon source, and carrying out hydrothermal treatment, so as to obtain Ni-Mn LDH@NF@C. According to the preparation method, by virtue of a stepwise hydrothermal-drying method, the preparation process and the required equipment are simple, raw material sources are rich, the reaction temperature is relatively low, the high temperature carbonization is not needed, and the large-scale production is easy to realize; and the Ni-Mn LDH@NF@C composite material is good in thermal stability, high in crystalline degree, large in specific surface area and strong in shape controllability and is one of ideal energy source materials.

The invention relates to an Ag3PO4/Mg-Al LDO (Layered Double Oxide) visible light composite photo catalyst, preparation and application thereof. The photo catalyst comprises Ag3PO4 nanometer particles and magnesium-aluminum double metal oxides Mg-Al LDO with a mass ratio of 1:10 to 5:1. A preparation method comprises the following steps of: dispersing magnesium-aluminum layered double hydroxides obtained by a co-precipitation method into the solution of soluble phosphate, adding a silver nitrate solution, stirring for 4-24 hours, washing and roasting to obtain the Ag3PO4/Mg-Al LDO visible light composite photo catalyst. The photo catalyst is applied to degrading and removing of anion pollutants in dye waste water. While maintaining the characteristic of strong adsorptive property of an adsorbent, the Ag3PO4/Mg-Al LDO visible light composite photo catalyst also has higher visible light catalytic activity so as to have good application prospect in the purification and treatment field ofthe dye waste water; and the preparation technology and production equipment are simple, environmentally friendly, and easy for industrial production.

The invention has for its object to provide a preparation method for preparing an anion-exchangeable LDH by decarbonation of a carbonate ion type LDH, which makes sure de carbonation is implemented with safety in a continuous manner while crystal shape, crystal structure and crystallinity are kept intact.

The invention provides a preparation method for preparing an anion-exchangeable, layered double hydroxide wherein a carbonate ion type layered double hydroxide (LDH) having a composition represented by a general formula: Q_xR(OH)_z(CO₃²⁻)_0.5-y/2(X⁻)_y.nH₂O where x is indicative of a numeral range of 1.8≦x≦4.2; z is indicative of 2(x+1); y is indicative of a minimum value of at least 0 that increases to less than 1 when anions (X⁻) remain or a part of anions is introduced; Q is a divalent metal ion; R is a trivalent metal ion; and n is 2±2 is used as a starting material, and y in said general formula increases to a maximum of 1 by substitution of a minus monovalent anion (X⁻¹) at a carbonate ion site thereby implementing substitution, characterized in that the starting material is dispersed in an aqueous solution mixed with a salt containing minus monovalent anions (X⁻) in an amount enough for substitution at the carbonate ion site while said aqueous solution is kept at a pH (hydrogen ion exponent) of greater than 4 to less than 7.

The invention provides a preparation method of a self-supporting ferronickel layered double hydroxide sulfide electrocatalyst. The preparation method comprises the steps of pretreating original foamednickel to obtain purified foamed nickel; dissolving nickel nitrate hexahydrate, iron nitrate nonahydrate and urea into deionized water according to a preset proportion to obtain a mixed solution, wherein the concentration of cations in the mixed solution is 40-45 mmol/L, and the concentration of urea in the mixed solution is 130-150 mmol/L; carrying out primary hydrothermal reaction on the mixedsolution to obtain NiFe LDH/NF; putting the NiFe LDH/NF into a thioacetamide solution, and carrying out a secondary hydrothermal reaction to obtain NiFe LDH-Sx/NF, wherein x is any number from 1 to 8.According to the preparation method of the self-supporting ferronickel layered double hydroxide sulfide electrocatalyst provided by the invention, the electrocatalyst shows excellent oxygen evolutionreaction catalytic activity under an alkaline condition, a ferronickel double hydroxide nanosheet structure directly growing on foamed nickel is beneficial to electron transfer, the catalytic surfacearea is increased, and the catalytic active sites are improved, so that diffusion of oxygen evolution reaction is facilitated.

The invention relates to a graphene/layered double hydroxide composite flame retardant and a preparation method of a polystyrene nanometer flame-retardant composite material. The preparation method comprises the following steps of: dissolving a carbon nanotube into graphene oxide colloid; stirring and performing ultrasonic dispersion until the materials are dispersed uniformly; adding M<2+> salt and Al<3+> salt; adding urea; performing a reflux reaction to obtain a graphene/carbon nanotube/layered double hydroxide composite assembling body; mixing the composite assembling body and polystyrene resin; and performing melt extrusion to obtain the polystyrene nanometer flame-retardant composite material. The graphene/carbon nanotube/layered double hydroxide composite assembling body is prepared by dispersing carbon nanotubes by a graphene oxide nanosheet, controlling the pH value of the solution by the urea and reducing the graphene oxide into the graphene. The polystyrene nanometer flame-retardant composite material prepared by the melt extrusion method has excellent flame resistance and mechanical properties.

LDH-osmate of the formula [MII(1-x)MIIIx(OH)2][OsO42-]x/2.zH2O wherein MII is a divalent cation selected from the group consisting of Mg2+, Mn2+, Fe2+, Co2+, Ni2+, Cu2+, Zn2+ and Ca2+ and MIII is a trivalent ion selected from the group consisting of Al3+, Cr3+, Mn3+, Fe3+ and Co3+, and x is the mole fraction having integral value ranging from 0.2 to 0.33, and z is the number of water molecules and ranges from 1 to 4, useful as, a catalyst, and a process for the preparation thereof and use thereof to manufacture vicinal diols.

The invention provides a nano-gold catalyst supported on combined metal oxide, a preparation method and an application thereof. The preparation method comprises the following steps: preparing layered double hydroxides (LDH) precursor crystal nucleus and dispersing the LDH precursor crystal nucleus into sucrose solution; then adding chloroauric acid solution in the obtained mixture so as to reduce Au3+ in HAuCl4 to Au single substances by using the reduction of glucose and fructose produced by sucrose hydrolysis; in the process of reduction, crystallizing the LDHs so as to obtain solid LDH supported on nano-gold; and carrying out high-temperature roasting on the solid LDH supported on the nano-gold so as to obtain the nano-gold catalyst supported on the combined metal oxide. The combined oxide of the catalyst is taken as a carrier on which the nanosize gold particles is supported, wherein the combined oxide refers to MgO or compound of ZnO and Al2O3, and the mole ratio of the MgO to the compound of ZnO and Al2O3 is 2-6:1; the gold capacity is 0.5 to 3 percent, the size of the gold particle is 8 to 15nm, and the gold particle is ellipsoidal or polyhedral. When the catalyst is used in the catalytic hydrogenation reaction of unsaturated aldehydes, the conversion rate of reactants reaches 60 to 97 percent, and the selectivity of cinnamyl alcohol is 40 to 75 percent.

The present invention relates to an in-situ preparation method of NiCo2Sx and NiCo2O4 on a conductive substrate and application of NiCo2Sx and NiCo2O4 in super capacitors and an anode catalyst of a direct methanol fuel cell (DMFC). The preparation method comprises two steps of electro-deposition and sulfuration (or calcination). The conductive substrate serves as a working electrode, electro-deposition is carried out under constant potential, and a cobalt-nickel layered double hydroxide (Co-Ni LDHs) is grown in situ growth. Co-Ni LDHs obtained through electro-deposition reacts with Na2S to prepare NiCo2Sx which is calcined in the air to prepare NiCo2O4. Through the two steps of electro-deposition and sulfuration (or calcination), in-situ growth of NiCo2Sx (NiCo2O4) on the conductive substrate is effectively realized, thereby avoiding usage of adhesives or conductive agents required for electrode preparation through a conventional coating method. The NiCo2Sx and NiCo2O4 grown directly on the conductive substrate can be directly used for researches of the super capacitors and anode non-platinum catalysts of the DMFCs. In an alkaline solution, NiCo2Sx and NiCo2O4 show a higher specific electric-capacity and a higher methanol catalytic oxidation efficiency than single metal sulfides such as NiSx and CoSx and single metallic oxides such as NiO and Co3O4.

The invention provides a preparation method of LDHs (magnesium-based layered double hydroxides). According to the method, calcium oxides or calcium magnesium oxides are used as an alkali source, calcium oxides or calcium magnesium oxides and a magnesium salt are subjected to a precipitation reaction, magnesium hydroxide precipitates are produced, then the magnesium hydroxide precipitates and divalent and trivalent soluble metal nitrates or chlorides are used as raw materials, LDHs are prepared through a liquid-solid phase reaction, and byproducts, namely, magnesium chlorides or magnesium nitrates, can be used as raw materials. The method has the advantages that the raw materials are rich in source, the price is low, the preparation process is simple, reaction conditions are mild, industrial production is facilitated and the like, and prepared LDHs can be widely applied to fields of catalysis, adsorption, environmental protection, high-polymer plastic and the like.

Adsorbents and methods of use thereof are provided. One representative, among others, includes an adsorbent having an alkali metal promoted, mixed trivalent layered double hydroxide (LDH) composition. When the mixed trivalent layered double hydroxide (LDH) composition is heated to a temperature ranging from about 300° C. to 450° C., an the adsorbent having an adsorption capacity of at least 0.8 millimoles of CO₂ adsorbed per gram of adsorbent is formed.

The invention provides a three-dimensional multi-layered structure cobalt-nickel-aluminum ternary metal electrocatalyst for oxygen evolution reaction as well as a preparation and application method thereof. The electrocatalyst is based on layered double hydroxides (LDHs) and zeolite imidazole metal-organic frameworks (ZIF-67), nickel foam (NF) serves as a substrate, and a ZIF-67/CoNiAl-LDH/NF three-dimensional multi-layed structure catalyst is synthesized through a two-step hydrothermal method. The electrocatalyst as well as the preparation and application method thereof have the advantages that through the introduction of the two-dimensional ZIF-67, the electrochemical active area of the catalyst can be improved, the formed unique three-dimensional multi-layed porous structure and a carrier with high specific surface area and abundant pore channels are beneficial for reducing the potential barrier of the oxygen evolution reaction, in addition, a super-hydrophobic interface is formed between a solid phase and a liquid phase, so that oxygen can be easily desorbed, the occurrence of the oxygen evolution reaction can be promoted, the electrocatalyst is applied to the oxygen evolutionreaction, the electric current density is 10 mA/cm<2>, the reaction overpotential is 0.3-0.41V, the Tafel slope is 88-245 mV/dec<-1>, in addition, the stability is good, and a good application prospect can be achieved.

The invention provides a three-dimensional flower-like layered double hydroxide and a preparation method thereof. In the preparation of the three-dimensional flower-like layered double hydroxide, aluminum sulfate or aluminum ammonium sulfate, soluble divalent metal salt and alkali are used as raw materials; the characteristic that sphere-like micron-sized aluminium hydroxide particles can be rapidly formed by solution of aluminum sulfate and aluminum ammonium sulfate, of which the pH value is 3.7 to 4, under a temperature of 95 to 100 DEG C is utilized; after being prepared, the micron-sized particles react with the divalent metal salt and the alkali, so that a great amount of LDH (Layered Double Hydroxide) crystal nuclei can be rapidly formed on the surface of aluminium hydroxide; and finally, three-dimensional flower-like structure LDH are formed. A prepared LDH laminate has a thickness of about 10 to 20nm; and the BET (Brunauer-Emmett-Teller) specific surface area of the prepared LDH laminate is greater than 140 m<2>/g and is much greater than that of common LDH. The preparation method disclosed by the invention is simple, is simple and convenient to operate, does not require high temperature and high pressure, does not need to use an organic solvent and a surfactant and is low in cost. The three-dimensional flower-like layered double hydroxide can be widely applied to the fields of adsorption separation, catalysis, high polymer materials and the like.

The invention relates to a corrosion resistant hydrotalcite/polyelectrolyte composite film and a preparation method thereof, which belongs to the technical field of metallic corrosion protection. The general chemical formula of the corrosion resistant hydrotalcite/polyelectrolyte composite film is (PEI/PAA)m/(I-LDHs)n/(PAA/AEI)m, wherein the PEI stands for polyethyleneimine, the PAA stands for polyacrylic acid, and the I-LDHs stands for inhibitor layered double hydroxides. The preparation method comprises the following steps: firstly, the inhibitor layered double hydrotalcites is prepared, then the inhibitor layered double hydrotalcites and the polyelectrolyte are helically coated on an alumina substrate or a stainless steel substrate, and finally, the corrosion resistant hydrotalcite/polyelectrolyte composite film is prepared by heating the inhibitor layered double hydrotalcites and the polyelectrolyte helically coated on the alumina substrate or the stainless steel substrate and performing crosslinking treatment to the same two. The invention has the advantages that the film is even and compact, has firm combination force with the substrate and excellent corrosion resistance, mild preparation condition, wide application range and good application prospect and overcomes the defects of loose and porous structure and short corrosion resistant life of the pure hydrotalcite film; and hydrotalcite interlayer inhibitor molecules perform driving inhibition function.

The invention belongs to the technical field of nanometer material preparation and relates to a preparation method for a nanosheet of uniformly dispersed layered double hydroxides (LDHs). The preparation method comprises the steps as follows: firstly, mixing a soluble bivalent inorganic salt M<2+>Y with a soluble trivalent inorganic salt M<3+>Y and dissolving in de-ionized water to prepare a salt solution; secondly, preparing an alkali solution by adopting the conventional technology; thirdly, fully mixing and reacting the salt solution with the alkali solution by utilizing a micro-channel reactor to obtain deposits of LDHs; and lastly, fully washing the deposits with the de-ionized water and centrifuging to obtain jelly with a single-layer nanosheet, which is the nanosheet of uniformly dispersed LDHs. The nanosheet of uniformly dispersed LDHs is simple to prepare, moderate in preparation conditions, low in cost, environment-friendly in production, wide in application range, and high in economic value.

Generally, systems for air and water purification using unpowered charged sorbent mediums (3) which may include layered double hydroxide (LDH) (1) compositions, lignin (2), and methods of sorbing inorganic or organic material(s) onto such mediums, including anionic contaminants (10), cationic contaminants (11), non ionic organic contaminants (20), and even biological agents (7) such as bacteria or viruses present in liquids or gases.

The invention discloses a one-step electrosynthesis method of an iron-based hydrotalcite nanosheet array. The present invention adopts a simple and rapid one-step electrosynthesis method to prepare different kinds of iron-containing hydrotalcite nanosheet arrays on various conductive substrates for the first time, and provides a relatively general method for the simple and rapid preparation of iron-based hydrotalcites. By adjusting the electrosynthesis time, the size and density of the hydrotalcite nanosheets were well regulated to achieve the best performance. The invention not only provides a brand-new and relatively general method for preparing iron-based hydrotalcite nano-arrays, but also broadens the application field of hydrotalcite-based materials. Capacitor electrode materials (SCs), lithium-ion battery electrode materials, and biosensing all have broad application prospects.

A process for the preparation of high quality amine oxides by reacting a tertiary or secondary amine with hydrogen peroxide as an oxidant in the presence of a recyclable heterogeneous layered double hydroxide exchanged with one of the anions of transition metal oxides as a catalyst in an organic solvent at a temperature ranging between 10-25° C. for a period of 1-6 hours under continuous stirring and separating the product by simple filtration and subsequently evaporation of solvents by known methods.

Disclosed is a layered double hydroxide capable of delamination in water comprising a plurality of basal layers of a double hydroxide of Formula:

M(II)_1-xM(III)_x(OH)₂

wherein M(II) is Mg, Zn or a combination thereof, M(III) is Al, and x is 0.2 to 0.33 and a plurality of intercalated layers between each adjacent basal layers of Mg acetate, Zn acetate or Ce acetate and water of intercalation. A process for producing the layered double hydroxide is also disclosed. The layered double hydroxide find use as an vehicle component or an anti-corrosive pigment of water-based protective coatings for metallic substrates, and as a humectant or a stabilizing agent for cosmetic preparations such as lotions, creams or foundations.