RU2115474C1 - Method of preparing superfine catalysts on metal carriers - Google Patents

Abstract

FIELD: catalyst production. SUBSTANCE: invention relates to catalysts applicable in various chemical-engineering processes as well as for treating waste water. Metal particles are directly applied onto carrier from water-in-oil type microemulsions: metal/water/surfactant/organic solvent prepared by reducing their water-soluble salts contained in microemulsions: metal salt/water/surfactant/organic solvent. To that end, metal salt microemulsion is mixed with reducing agent (sodium or ammonium hypophosphite) microemulsion. As surfactant, ethoxylated alkylphenol is used. EFFECT: increased fineness of applied metal phase and enabled controlling distribution of metal particles on carrier. 2 dwg

Description

 The invention relates to methods for producing catalysts that can be used in various chemical and technological processes of the chemical, oil, gas industry, for wastewater treatment, etc.

 Closest to the claimed method is considered the direct introduction of finely dispersed particles from a colloidal metal solution into the porous structure of the carrier in the form of a dispersion of finely dispersed particles, including in the presence of surfactants (Colloids and Surfaces, v / 5, 1982, p.209-225).

);
- неустойчивость исходного коллоидального раствора, приводящая к агрегированию частиц;
- использование крупнопористых носителей с пониженной уд. поверхностью, что не позволяет получать нанесенную фазу с размерами частиц 30 -

.Disadvantages:
- the inability to obtain the applied monodisperse phase with a narrow particle size distribution, which vary over a wide range (30-

);
- instability of the initial colloidal solution, leading to aggregation of particles;
- the use of large-porous media with low beats. surface that does not allow to obtain the applied phase with a particle size of 30 -

.

 The problem of increasing the dispersion of the deposited metal phase and the possibility of controlling the distribution of metal particles on the carrier is solved.

The essence of the claimed technical solution consists in developing a technology in which microemulsions of metals are used as a solution: M ⁰ / H ₂ O / surfactant / organic solvent, the so-called water-in-oil microemulsions, where the oil-organic solvent is cyclohexane, heptane, octane, etc., and as a surfactant - ethoxylated alkyl phenol of the general formula: RC ₆ H ₄ -O (C ₂ H ₄ O) nH, where R is an alkyl radical with C ₈ -C ₁₀ , n = 6 - 8, ( MV 488), as M - any metal from the group of noble or heavy, or silver.

The content of components in the system M ⁰ / H ₂ / organic solvent, mmol / l:
Metal - 3.0 - 9.3
Surfactant - not less than 0.19
Organic Solvent - Else
The method is as follows.

Dried at 100 - 150 ^o C the carrier (to remove moisture from it) is impregnated with a specific volume of metal microemulsion with a content of 3.0 - 9.3 mmol / l in the aqueous-organic phase corresponding to the total pore volume "by moisture capacity". Then the carrier is dried in air to remove the solvent and get a CT with a content of 0.01 - 0.5% M ⁰ / surfactant / carrier.

The claimed method it is possible to obtain catalysts containing any of the noble or heavy metals, or silver, and as a carrier - Al ₂ O ₃ , SiO ₂ , Al ₂ O ₃ • SiO ₂ , MgO, activated carbon, etc. In this case, the microemulsion is obtained by mixing two initial microemulsions: microemulsions of the initial metal salt, to obtain which they are used with 0.5-1M aqueous solutions, and microemulsions of a reducing agent — sodium or ammonium hypophosphite at T _bales or room temperature. To obtain a microemulsion of a reducing agent, 0.5-1M aqueous solutions of hypophosphite are also used. The starting salts may be AgNO ₃ , PdCl ₂ , CuNO ₃ , etc., i.e. 0.5-1M water-soluble metal salts, the solutions of which are added in an amount of 0.5-1.5 ml to 80 ml of a 0.19M surfactant solution in an organic solvent (cyclohexane, heptane, octane, etc.), where the surfactant is ethoxylated alkyl phenol with M.V. 488.

A hypophosphite microemulsion is obtained by adding 0.5-1.5 mm 1M aqueous hypophosphite to 80 ml of a 0.19 M surfactant solution, the mixture is shaken vigorously and an ME NaH ₂ PO ₂ microemulsion is obtained. Subsequent mixing of the two obtained starting emulsions is carried out by introducing ME hypophosphite into the ME metal salt with vigorous shaking. The reaction ends in 30 minutes:
AgNO ₃ + NaH ₂ PO ₂ + H ₂ O ---> Ag ⁰ + NaH ₂ PO ₃ + 1 / 2H ₂ + HNO ₃ .

, о чем свидетельствует отсутствие в рентгенограммах образцов, полученных испарением растворителя, Ag/ПАВ, контрольных дифракционных пиков объемных частиц Ag, а также вид кривой поглощения в ЭСДО-спектрах (рис.1).The microemulsion Ag is a dark red solution of Ag in an organic solvent, stable for several months. The average particle size of the metal in it according to the XRD and ESDO less

, as evidenced by the absence in the X-ray diffraction patterns of samples obtained by evaporation of the solvent, Ag / surfactant, control diffraction peaks of bulk Ag particles, as well as the shape of the absorption curve in the ESDO spectra (Fig. 1).

Example 1. Obtaining catalyst Ag ⁰ / media.

. Полученный КТ рентгеноаморфен. В ЭСДО-спектре (кривая 1) полоса поглощения при 385HM указывает на их размер

.To 10 g of dried at 100-150 ^o C Al ₂ O ₃ with a total pore volume of 0.44 cm ³ / g added with stirring 4.4 ml of MEAg ⁰ with an Ag content of 0.2 mmol / l (or 2.95 mg). The solvent is evaporated in air or in vacuum, the catalyst is washed with water, then with alcohol to remove surfactants, dried and Ag ⁰ / Al ₂ O _{3 is} obtained with an Ag content of 0.0295% and a particle size thereof

. The resulting CT is X-ray amorphous. In the ESDO spectrum (curve 1), the absorption band at 385HM indicates their size

.

Example 2. To obtain a more finely dispersed QD, it is necessary to use a metal ME with a higher content (up to 9.3 mmol / L, or 0.44% M / Al ₂ O ₃ ), or after removing the solvent, the metal ME is re-applied and 0.088% is obtained M / Al ₂ O ₃ .

(кривая 2, дл. волны 385HM), тогда как по прототипу получают КТ Ag⁰/Al₂O₃ с 0,03% Ag.According to the analysis of particle size

(curve 2, long. wave 385HM), while the prototype get CT Ag ⁰ / Al ₂ O ₃ with 0.03% Ag.

. При этом исходная МЭ_Ag устойчива только в течение 1 сут, затем появляется осадок частиц серебра серого цвета. ЭСДО-спектр (кривая 2, с длиной волны 385 и 556нм) дает широкую полосу поглощения с двумя максимумами, что характеризует полидисперсность образца и наличие частиц Ag с размером и более

.Particle size according to RAF more than 30 -

. In this case, the initial ME _{Ag is} stable only for 1 day, then a precipitate of gray silver particles appears. The ESDO spectrum (curve 2, with a wavelength of 385 and 556 nm) gives a wide absorption band with two maxima, which characterizes the polydispersity of the sample and the presence of Ag particles with size and more

.

Claims (1)

A method of obtaining highly dispersed metal carrier catalysts, comprising directly applying to a carrier metal particles from a water-in-oil microemulsion M ^o / H ₂ O / surfactant / organic solvent obtained by the reduction of water-soluble metal salts included in the original microemulsion, characterized in that for application use a microemulsion composition, mmol / l:
Metal - 3.0 - 9.3
Surfactant - Not less than 0.19
Water - 0.35 - 1.0
Organic Solvent - Else
where the metal is selected from the group of noble or heavy metals or silver, ethoxylated alkyl phenol of the general formula R (C ₆ H ₄ - O (C ₂ H ₂ O) _n , where R is the alkyl radical C ₈ - C ₁₀ , n = 6-8, obtained by mixing two initial microemulsions - microemulsions of a metal salt and microemulsions of a reducing agent, which use sodium or ammonium hypophosphite.