LOW-TEMPERATURE REMOVAL OF H2S USING LARGE-SURFACE-AREA NANO-FERRITES OBTAINED USING A MODIFIED CHEMICAL COPRECIPITATION METHOD

Abstract

The present invention relates to H.sub.2S removal that may be contained in biogas or industrial process gases in concentrations of 35-15000 ppm. By means of nanoparticles of manganese ferrite MnxFe.sub.3-xO.sub.4 with x=0%, 0.1%, 0.3% and 0.5%, obtained by means of chemical co-precipitation from solutions of chlorides and at a temperature below 100 C. With surface area of 142-240 m.sup.2/g and particle size of 7-9 nm. And that is done through a set of components such as: pressure regulating valve, a flow meter, a piston flow rector, a pressure gauge, a three-way valve, a biogas measuring device, a gas scrubber and a burner biogas.

Claims

1. The use of magnetic nanoparticles of manganese ferrite MnxFe.sub.3-xO.sub.4 with x=0%, 0.1%, 0.3% and 0.5%, this material has the following characteristics: average nanoparticle size is 10 nm, the surface area of the nanoparticles used is 142 to 240 m.sup.2/gr, the density of the material is from 6,700 to 9,700 kg/m.

2. The manufacturing process of the nanoparticles described in claim 1, wherein the manufacturing method by means of modified chemical co-precipitation and with the following characteristics: stirring and dilution process of ferric chloride at a concentration of 0.483 M, the solution should be stirred at a speed of 200-2200 RPM and at a constant temperature of 25 C., he ratio of Fe+2/Mn+2 is between 0.177 M and 0.50 M, present in chemical reagents based on chlorides; the mixture of three solutions is carried out: ferric chloride, manganese chloride and ferrous chloride, the temperature must be elevated from 25 C. to 70 C., and with constant agitation of 20,000 RPM to 30,000 RPM, 10% ammonium hydroxide is added once the temperature of 70 C. is reached and stirring is raised to 45,000-48,000 RPM, a precipitate of ferrite nanoparticles is generated, then the solution is cooled to 25 C. containing the nanoparticles of manganese ferrite and washing is done by accelerated precipitation with magnets and decanting process until a pH of 7-8 is reached.

3. A process for the removal of H.sub.2S that may be contained in biogas or industrial process gases, by using ferrite nanoparticles with characteristics of claim 1, as follows: A. PREPARATION, the material preparation process is carried out by means of modified chemical co-precipitation, the use of solutions with ferrous and ferrous chlorides, the stirring speed of 20,000 to 48,000 RPM and at a temperature below 100 C.; B. USE OF FERRITES OBTAINED BY MODIFIED CHEMICAL CO-PRECIPITATION, the use of ferrite nanoparticles obtained by modified chemical co-precipitation, the material is placed in the form of tablets with a diameter of 0.0254-0.1 m and with a thickness of 0.01-0.05 m, the tablets are subjected to a compression of 0.25-2.5 psi. C. H.sub.2S REMOVAL SYSTEM, the system consists of a pressure regulating valve, a flow meter, a piston flow rector, a pressure gauge, a three-way valve, a biogas measuring device, a gas scrubber and a biogas burner.

Description

BRIEF DESCRIPTION OF THE FIGURES

[0023] FIG. 1 presents 5 steps necessary for the manufacture of the material by means of modified chemical co-precipitation.

[0024] FIG. 2 shows a 9-step process for the removal of H.sub.2S by a reactor containing magnetic nanoparticles obtained by the modified chemical co-precipitation method.

[0025] FIG. 3 shows a diffractogram of the magnetic material obtained after the manufacturing process. Said material before the removal process has a single magnetic phase corresponding to the reverse spinel ferrite. The average crystallite size presented in the diffractogram is 8.2 nm. It is observed that after the removal process there is a new phase of iron mono-sulphide (FeS).

[0026] FIG. 4 presents images made by transmission electron microscopy. The material has an average size of 8.9 nm.

BRIEF DESCRIPTION OF THE FIGURES:

[0027] In order to fully appreciate the entire process, I will allow myself to present a brief description. Based on the figures presented, the invention refers to the H.sub.2S removal process by using nanometric ferrites obtained at temperatures below 100 C. The process of obtaining the nanoparticles is through the modified process of chemical co-precipitation where the speed of agitation in the mixture of the chlorides used for the precipitation of ferrites is varied. The speed variation is in a range of 20,000 to 48,000 RPM. After obtaining the material, it should be washed until a pH in the range of 7-8 is reached, and then dried for 3 days at a temperature of 70 C.

DETAILED DESCRIPTION OF THE INVENTION

[0028] The synthesis of the ferrite nanoparticles with high surface area is carried out by a chemical method, with the help of a high RPM device and with a constant heating system.

[0029] Said method of FIG. 1 consists of the following steps: [0030] A. AGITATION. A stirring and dilution process of ferrous chloride is carried out at a concentration of 0.177 M. The solution must be stirred at a speed of 200-2200 RPM and at a constant temperature of 25 C. [0031] B. PREPARATION OF THE MIX. A stirring and dilution process of ferric chloride is carried out at a concentration of 0.483 M. The solution must be stirred at a speed of 200-2200 RPM and at a constant temperature of 25 C. The ratio of Fe +2/Mn+2 is between 0.177 M and 0.50 M, present in chemical reagents based on chlorides. [0032] C. WARM UP. The mixture of three solutions is carried out: ferric chloride, manganese chloride and ferrous chloride, the temperature must be elevated from 25 C. to 70 C. And with constant agitation of 20,000 RPM to 30,000 RPM. [0033] D. PRECIPITATION. 10% ammonium hydroxide is added once the temperature of 70 C. is reached and stirring is raised to 45,000-48,000 RPM, a precipitate of ferrite nanoparticles is generated. [0034] E. WASHING. The solution is cooled to 25 C. containing the nanoparticles of manganese ferrite and washing is done by accelerated precipitation with magnets and decanting process until a pH of 7-8 is reached.

[0035] In order to specify some results, he following results are presented, but not limited to, the following results,

[0036] The graph of FIG. 2, The process of H.sub.2S removal by ferrite nanoparticles in a reactor is shown, [0037] A. BIOGAS. The H.sub.2S contained in synthetic biogas with concentrations above 5000 ppm is directed through a port of entry into the system where the removal will take place. Biogas is composed of 55% CH.sub.4 and 40% CO.sub.2 and 5% Balance gas. [0038] B. FLOW CONTROL. The flow control is carried out by means of an adjustable opening valve and with a range of 0.5 to 500 LPM to be able to control the amount of gas that passes through the removal filter. [0039] C. FLOW MEASUREMENT. The flow must be measured after being controlled in order to estimate the amount of H.sub.2S that the filter is able to remove for a period of time during the biogas generation process. [0040] D. REACTOR. The H.sub.2S removal process is carried out in a reactor known as a piston flow and with a volume of 0.5 to 30 L. The material is placed in the form of tablets with a diameter of 0.0254-0.1 m and a thickness of 0.01-0.05 m. The pads are subjected before placing them in the reactor at a compression of 0.25-25 psi and a heat treatment of 70 C. for 4 hours. When the pads are placed inside the reactor, the gas is passed from the bottom of the reactor so that a phenomenon of diffusion of the material occurs until it reaches its maximum saturation when in contact with the Biogas containing H.sub.2S. [0041] E. MANOMETER. The pressure gauge inside the system is to regulate the biogas pressure that enters the reactor where the ferrite nanoparticle tablets are located. System pressure should be maintained between 2-35 psi. [0042] F. THREE-WAY VALVE. The three-way valve is used in one position to be able to perform the H.sub.2S removal percentage measurement after passing through the filter of ferrite nanoparticles obtained by modified chemical co-precipitation. [0043] G. BIOGAS MEASUREMENT. The percentage of H.sub.2S removed by the reactor-shaped filter is measured using a biogas probe. [0044] H. GAS WASHER. In the other position of the three-way valve, the biogas is passed to a gas scrubber in order to remove the CO.sub.2 contained in the biogas. [0045] I. BURNER. The gas burner is a system in which biogas combustion is generated and process heat is generated but with a biogas without H.sub.2S concentration. [0046] J. The graph of FIG. 3 shows a diffractogram showing the phases present in the ferrites before being subjected to the H.sub.2S removal process. In the lower part there is the material after removing H.sub.2S and it is observed that there is the presence of iron mono-sulfide (FeS), which confirms that there is removal by means of the nanoparticles obtained through the modified chemical co-precipitation. [0047] K. The graph of FIG. 4 shows an image with ferrite nanoparticles with an average size of 8.9 nm and a surface area of 142 m.sup.2/g.