RU2690849C1 - Catalyst for combustion of fuel and industrial wastes - Google Patents

Abstract

FIELD: chemistry.SUBSTANCE: invention relates to catalytic chemistry and specifically to molybdenum-supported sulphide catalysts on a three-dimensional porous support which can be used for combustion of any type of fuel and industrial wastes, including those containing sulphur compounds (hydrocarbon fuel, waste oil, wood, hard coal, peat, wood and vegetable wastes, tires and wood-particle boards), and detoxification of gas emissions. Developed catalyst composition can also be used for purification and synthesis gas production. Catalyst for combustion of fuel and industrial wastes contains heat-resistant porous carrier with copper oxide applied on it, wherein molybdenum oxide is additionally applied on carrier in following ratio of components, wt. %: copper oxide - 1.0–3.0; molybdenum oxide - 2.0–4.5; support - the rest. Carrier can be made of γ-aluminium oxide or chamotte.EFFECT: technical result of the invention is to increase the combustion temperature of fuel and industrial wastes while reducing the amount of toxic substances formed during combustion of fuel and wastes, including those containing sulphur compounds.1 cl, 3 tbl, 41 ex

Description

The invention relates to the field of catalytic chemistry, namely to molybdenum sulfide catalysts on a three-dimensional porous carrier, which can be used to burn any type of fuel and industrial waste, including those containing sulfur compounds (hydrocarbon fuel, waste oils, wood, coal, peat , wood and vegetable waste, tires and chipboards), and detoxification of gas emissions. The developed composition of the catalyst can also be used for the purification and production of synthesis gas.

Known catalysts for the conversion of hydrocarbons containing a metal of group VIII (iron, cobalt, nickel, ruthenium, rhodium, palladium, osmium, iridium and platinum) on the carrier. Preference is given to platinum or palladium, or a mixture thereof. Acceptable catalyst includes from 0.1 to 1 wt.%. The best option is the metal content from 0.25 to 0.5 wt.%. A wide range of carrier materials is currently available, among which the most common is alumina. The material of the carrier may have a spherical shape or the shape of granules of another type. The substrate can be characterized by an almost continuous multichannel ceramic structure, such as in a foamed material or a monolith with a homogeneous channel system (patent for invention of the Russian Federation No. 2151164, IPC: C10G9 / 36).

Other catalysts based on noble metals for hydrocarbon conversion are also known (application for invention of the Russian Federation No. 98103990, IPC: B01J21 / 06, application for the invention of the Russian Federation No. 2006122808, IPC: B01J23 / 40).

The disadvantage of these catalysts is the use of expensive noble metals and their low resistance to the effects of catalytic poisons.

Known nickel-copper oxide catalyst on a substrate made of aluminum or its alloy. The catalyst is obtained by the plasma-electrochemical method by treating the substrate in an alkaline electrolyte containing nickel acetate and copper acetate and additionally including trisodium phosphate, tetraborate and sodium tungstate in the following ratio of components, g / l: nickel acetate Ni (CH ₃ COO) ₂ · 4H ₂ O -5-20; copper acetate Cu (CH ₃ COO) ₂ · H ₂ O-1.3-5.0; trisodium phosphate Na ₃ PO ₄ · 12H ₂ O-20-30; sodium tetraborate Na ₂ B ₄ O ₇ · 10H ₂ O-10-20; sodium tungstate Na ₂ WO ₄ · 2H ₂ O-1-3. Plasma-electrochemical treatment is carried out in galvanostatic mode by pulsed current, either alternating or alternating unipolar, with a pulse duration of 0.0033-0.04 s, voltage 240-400 V, effective current density 5-20 A / dm ² and consumption of the amount of electricity 1500 -6000 C / dm ² formed by the catalytically active layer. The resulting catalyst is stable in the temperature range of 300-500 ° and provides a degree of conversion of CO to CO ₂ in a wide range from 37 to 97% (RF patent for invention No. 2342999, IPC B01J 37/34).

The disadvantage of the catalyst is the high content of active metal and complex production technology, limited scope of its application.

Known catalyst for flameless combustion of natural gas. This catalyst contains as an active component a period IV metal oxide, for example, nickel oxide or cobalt oxide, or iron oxide, or manganese oxide, deposited on a porous ceramic carrier in the form of a multichannel monolith with a specific surface area of 0.3 - 20 m ² and a pore volume 0.21 - 0.41 cm ³ / g (RF patent for invention No. 2086298, IPC: B01J23 / 70, B01J23 / 34, B01J23 / 70).

However, this catalyst is characterized by a poorly developed specific surface area and is recommended for only one type of fuel.

Known alumocobaltmolybdenum catalyst for hydrodesulfurization of crude oil, containing in its composition cobalt oxide, molybdenum oxide and alumina, in the following ratio of components, wt.%: Cobalt oxide - 3.0-9.0, molybdenum oxide - 10.0-24.0 wt.%, aluminum oxide - the rest (RF Application No. 2002124681, IPC: C10G 45/08, B01J 23/887, 16.09.2002).

Also known is an industrial catalyst for hydrotreating hydrocarbon feedstock containing cobalt or nickel, molybdenum and carrier (Al ₂ O ₃ ) in its composition, and having a high catalytic activity in hydrogenation reactions of sulfur, nitrogen and oxygen-containing compounds (RF patent for invention No. 2478428, IPC: B01J 23/882).

A disadvantage of the known solutions is the suitability of catalysts only for the production of petroleum products with low sulfur content.

Known catalyst for burning fuel and cleaning gas emissions from nitrogen oxides and carbon (II), containing heat-resistant porous media coated with copper oxide and methylcyclopentadienyl tricarbonyl manganese, in the following ratio of components, wt.%: Copper oxide - 0.5-2, 0; methyl cyclopentadienyltricarbonyl manganese — 1.0-3.0; the carrier is the rest.

The disadvantage of this catalyst is the need to use organic solvents for the preparation of the original impregnating solution of methyl cyclopentadienyl tricarbonyl manganese. In addition, the catalyst is unstable to the action of sulfur-containing compounds.

Closest to the proposed solution is a catalyst for burning fuels, which includes a heat-resistant porous carrier based on aluminum oxide or chamotte coated with nickel oxide and copper oxide in the following ratio of components, mass. %: copper oxide - 1.0-3.0; nickel oxide - 0.5-2.5; the carrier is the rest (Patent of the Russian Federation for the invention No. 2394643, IPC: B01J 23/72, B01J 23/755, B01J 21/04, F23Q 2/30).

This catalyst provides high heat transfer and efficient cleaning of flue gases from toxic substances such as oxides of nitrogen, carbon, hydrogen, methane, alcohols, aldehydes and esters.

The disadvantage of the known catalyst is its instability to the action of catalytic poisons - sulfur-containing compounds.

It is known that catalysts containing metals of the VI, VIII groups of the Mendeleev system are quickly poisoned with sulfur compounds (Gerasimov Ya.I. The course of physical chemistry. T. 2. 1964. 624 p.). Since sulfur-containing compounds are present in all types of hydrocarbon fuels and many industrial wastes, when they are burned, the active centers of the catalyst are poisoned.

The technical problem of the present invention is to develop an effective catalyst that does not contain noble metals, provides high-temperature combustion of any type of fuel and industrial waste, including those containing sulfur compounds, as well as providing detoxification of gaseous emissions.

The technical result is to increase the temperature of combustion of fuel and industrial waste while reducing the amount of toxic substances formed in the process of burning fuel and waste, including those containing sulfur compounds.

The problem is solved by the fact that in the catalyst for combustion of fuel containing a heat-resistant porous carrier coated with copper oxide, according to the decision, molybdenum oxide is additionally deposited on the carrier, in the following ratio of components, mass. %

copper oxide -1.0-3.0;

molybdenum oxide - 2.0-4.5;

the carrier is the rest.

The carrier can be made of γ-alumina or chamotte. The carriers used are distinguished by a sufficient specific surface area, high thermal stability, and are resistant to thermal loads arising during fuel oxidation reactions, which ensures the long-term chemical and mechanical stability of the catalyst.

γ - Aluminum oxide has a specific surface of 150-200 m ² / g, an average pore radius of 40-50, crushing strength - 25 MPa. Chamotte has an apparent density of 0.4 g / cm ³ , compressive strength of 3.5 N / mm ² and thermal conductivity of 70 W / mK at 650 ° C.

The proposed catalyst is obtained by sequential deposition of copper acetate and ammonium molybdate on a carrier by impregnation from aqueous solutions of salts: copper acetate and ammonium paramolybdate with dimethyl sulfoxide, respectively, drying after each impregnation and calcination in a stream of air.

To confirm the achievement of the technical result, catalysts with different content of active components were prepared (examples 1-35). Table 1 shows the quantitative content of substances in the catalyst and working solutions used in the process of manufacturing catalysts.

The catalysts were prepared as follows.

The γ-alumina carrier (g-Al ₂ O ₃ with Ssp. = 196 m ² / g), made in the form of cylinders with a diameter of 4 mm and a height of 4-5 mm, in the amount of 50.0 g was calcined in a muffle furnace at a temperature of 500 ° C within 2 hours. Prepare 100 ml of an aqueous solution containing the required amount of copper acetate, and pour calcined carrier over it. Soaked at room temperature for 24 hours, evaporated the remaining solution of copper acetate in a water bath, dried the sample at a temperature of 120 ° C, and then soaked in 100 ml of an aqueous solution containing the required amount of ammonium paramolybdate and dimethyl sulfoxide for 24 hours. Then an excess of the solution was evaporated, the catalyst was dried at 200 ° C and calcined at 300 ° C.

Catalysts, in which carrier chamotte, which is a mixture of silica and aluminum, was used, were prepared in a similar way.

The copper content in the impregnating solution was determined by the iodometric method in an acidic medium by adding a small amount of 1 M solution of sulfuric acid and after the introduction of potassium iodide, the titration was performed with sodium thiosulfate in the presence of starch. The titrated solution was ivory-colored due to the presence of poorly soluble copper (I) iodide.

A quantitative analysis of molybdenum was carried out by the complexometric method with the reverse titration of an excess solution of ethylenediaminetetraacetic acid with a solution of copper sulfate with the indicator PAN (pyridyzononaphol).

Examples of the composition of catalysts, as well as the quantitative content of substances in the working (impregnating) solution used for the preparation of catalysts, are given in table 1.

Table 1. Examples of the content of substances in the catalyst and working solutions

No
apply
ra Content
molybdenum oxide in the catalyst,
masses % Content
copper oxide in the catalyst, mass. % Content
ammonium paramolybdate in the impregnating solution, g Content
copper acetate in the impregnating solution, g DMSO content
in the impregnating solution, g one 1.5 1.0 0,948 1,335         0.502 2 1.5 1.5 0,948 2,003         0.502 3 1.5 2.0 0,948 2,670         0.502 four 1.5 2.5 0,948 3,338         0.502 five 1.5 3.0 0,948 4,006         0.502 6 2.0 1.0 1,264 1,335 0.670 7 2.0 1.5 1,264 2,003          0.670 eight 2.0 2.0 1,264 2,670 0.670 9 2.0 2.5 1,264 3,338 0.670 ten 2.0 3.0 1,264 4,006 0.670 eleven 2.5 1.0 1,580 1,335 0.838 12 2.5 1.5 1,580 2,003 0.838 13 2.5 2.0 1,580 2,670 0.838 14 2.5 2.5 1,580 3,338 0.838 15 2.5 3.0 1,580 4,006 0.838 sixteen 3.0 1.0 1,896 1,335 1,005 17 3.0 1.5 1,896 2,003          1,005 18 3.0 2.0 1,896 2,670          1,005 nineteen 3.0 2.5 1,896 3,338 1,005 20 3.0 3.0 1,896 4,006 1,005 21 3.5 1.0 2,212 1,335 1,173 22 3.5 1.5 2,212 2,003 1,173 23 3.5 2.0 2,212 2,670          1,173 24 3.5 2.5 2,212 3,338 1,173 25 3.5 3.0 2,212 4,006 1,173 26 4.0 1.0 2,528 1,335 1,340 27 4.0 1.5 2,528 2,003 1,340 28 4.0 2.0 2,528 2,670 1,340 29 4.0 2.5 2,528 3,338 1,340 thirty 4.0 3.0 2,528 4,006 1,340 31 4.5 1.0 2,844 1,335 1.507 32 4.5 1.5 2,844 2,003 1.507 33 4.5 2.0 2,844 2,670 1.507 34 4.5 2.5 2,844 3,338 1.507 35 4.5 3.0 2,844 4,006 1.507 36 5.0 1.0 3.160 1,335 1,675 37 5.0 3.5 3.160 4.676 1,675 38 5.0 0.5 3.160 0.667 1,675 39 1.5 3.5 0,948 4.676 0.502 40 1.5 3.0 0,948 4,006 0.502 41 2.0 3.5 1,264 4.676 0.670

The influence of the catalysts obtained in examples 1-41 on the temperature of the combustion products of the fuel, as well as on the ecological purity of the combustion of various fuels, was studied, the results of the research are shown in Tables 2 and 3.

The tests were carried out in a 250 kW catalytic heat generator with the combustion of natural gas, coal, fuel oil, sludge and rubber waste with a load of 4 kg of catalyst at a contact time of 0.8 seconds. The temperature of the combustion products was determined by a thermocouple, and the composition of the exhaust gas was determined with an AGM-510M gas analyzer.

Table 2. The influence of the composition of the catalyst on the temperature of the combustion gases of the fuel

No
an example Content
molybdenum oxide,
masses % Content
copper oxide, mass. % Content
aluminum oxide, mass. % The temperature of the combustion products of coal, ° C one 1.5 1.0 98.5 765 2 1.5 1.5 97.0 771 3 1.5 2.0 96.5 777 four 1.5 2.5 96.0 790 five 1.5 3.0 95.5 790 6 2.0 1.0 97.0 820 7 2.0 1.5 96.5 835 eight 2.0 2.0 96.0 846 9 2.0 2.5 95.5 853 ten 2.0 3.0 95.0 810 eleven 2.5 1.0 96.5 830 12 2.5 1.5 96.0 845 13 2.5 2.0 95.5 844 14 2.5 2.5 96.0 851 15 2.5 3.0 94.5 853 sixteen 3.0 1.0 97.0 850 17 3.0 1.5 95.5 847 18 3.0 2.0 95.0 845 nineteen 3.0 2.5 94.5 840 20 3.0 3.0 94.0 847 21 3.5 1.0 95.5 851 22 3.5 1.5 95.0 850 23 3.5 2.0 94.5 841 24 3.5 2.5 94.0 851 25 3.5 3.0 93.5 847 26 4.0 1.0 95.0 848 27 4.0 1.5 94.5 849 28 4.0 2.0 94.0 842 29 4.0 2.5 93.5 846 thirty 4.0 3.0 93.0 852 31 4.5 1.0 94.5 848 32 4.5 1.5 94.0 846 33 4.5 2.0 93.5 841 34 4.5 2.5 93.0 839 35 4.5 3.0 92.5 840 36 5.0 1.0 94.0 820 37 5.0 3.5 91.5 810 38 5.0 0.5 94.5 800 39 1.5 3.5 95.0 790 40 1.5 3.0 95.5 780 41 2.0 3.5 94.5 800

The data presented in table 2 indicate that in the ranges of the mass fraction of copper oxide from 1 to 3% and molybdenum oxide from 2 to 4.5%, the temperature of the combustion products of the fuel in the catalytic heat generator is maximum.

The catalytic activity of the alumina-molybdenum catalyst is due to the presence on the catalyst surface of centers of different structure, active in the course of oxidation reactions of the components of the fuel and the redox interaction of nitrogen oxides, carbon (II) and hydrocarbons. In the presence of dimethyl sulfoxide, at the catalyst preparation stage, copper and molybdenum oxides are sulfided to form the corresponding sulfides (CuS, MoS ₂ , CuMoS), which are resistant to the action of catalytic poisons (compounds of sulfur, nitrogen, oxygen, chlorine).

Table 3. The composition of the exhaust gases during combustion of various fuels

View
fuel Flue gas composition NO _X , mg / m ³ CH ₄ mg / m ³ CO, mg / m ³ Sulfur _total , mg / m ³ CO ₂ ,
% vol. Natural
gas 46 20 34 28 7.9 Mazut 41 53 50 thirty 10.1 Coal 64 40 15 31 7.2 Oil sludge 60 32 22 26 7.4 Rubber waste 42 26 32 22 9.4

Thus, the proposed catalyst provides high heat transfer and effective cleaning of flue gases from toxic substances, including sulfur-containing (table 3).

In addition, the absence of noble metals in the composition of the catalyst makes it possible to reduce its cost and to make it more accessible to the end user.

Claims (3)

1. A catalyst for burning fuel and industrial waste containing a heat-resistant porous carrier coated with copper oxide, characterized in that the carrier is additionally coated with molybdenum oxide, in the following ratio, wt.%: copper oxide 1.0-3.0 molybdenum oxide 2.0-4.5 carrier rest 2. The catalyst according to claim 1, characterized in that the carrier is made of γ-alumina or chamotte.