CN102200287A - Method for catalyzing and purifying low molecular oxygen-containing organic waste gases - Google Patents

Abstract

The invention discloses a method for eliminating volatile oxygen-containing organic pollutants in an environment through complete catalytic combustion. In the method, a cerium oxide nanorod serves as a catalyst and air serves as an oxidant, so that low molecular oxygen-containing organic compounds are completely combusted in the presence of the catalyst and are converted into carbon dioxide and water. The catalyst of cerium oxide nanorod is high in activity, long in service life and particularly suitable for eliminating the low molecular oxygen-containing organic compounds at low temperature through complete catalytic combustion, and does not generate by-products or cause secondary pollution.

Description

A kind ofly be used for low molecule and contain oxygen organic exhaust gas catalytic purification method

Technical field

The present invention relates to the method that a kind of low molecule contains oxygen organic exhaust gas low-temperature catalytic burning, relate in particular to the catalyst that contains oxygen organic exhaust gas low-temperature catalytic burning.

Background technology

In many industrial processes, low molecule oxygen-containing organic compound such as ethyl acetate, ethanol, acetone are widely used in every field as the most frequently used solvent.Yet its boiling point is low, and volatility is big, easily environment is caused the influence of certain degree in correlated process.Low molecule oxygen-containing organic compound has the main harm of human body: eye, nose, throat are had spread effect; High concentration can cause respiratory paralysis when sucking, and anesthetic effect is arranged, and can produce acute pulmonary edema and cause the infringement of liver, kidney; Low concentration contacts for a long time, can cause the opacity of the cornea, SA, leukocytosis etc.; Symptoms such as that the person of wrongly taking can produce is nauseating, vomiting, stomachache, diarrhoea; Sensitization is arranged, and irritated crowd can cause bleeding gums because of the nervus vasculairs obstacle, can cause eczema-like dermatitis simultaneously.Low simultaneously molecule oxygen-containing organic compound very easily fires, and can form explosive mixture with air, and chance naked light, high heat energy cause combustion explosion, and contacting with oxidant can fierce reaction.Except that itself harmfulness to environment, also can with airborne other substance reaction, generate strong oxidizing property pollutants such as ozone; Have an effect with the organic component in the aerosol, produce the Secondary Organic aerosol and pollute.At present, the method for handling this waste gas mainly contains charcoal absorption facture, acid-base neutralization method, plasma method, catalytic oxidation, Production by Catalytic Combustion Process etc.Exhaust-gas treatment for the low molecule oxygen-containing organic compound of low concentration adopts catalytic combustion method more.

Low molecule oxygen-containing organic compound treatment of waste gas has its particularity, one, and the temperature drift that catalytic combustion is required is unfavorable for the safe handling of this waste gas; Its two, accessory substance is many, easily causes secondary pollution.Be used to handle the catalyst type of hanging down molecule oxygen-containing organic compound catalytic combustion at present and be mainly three major types: composite oxide catalysts such as perovskite composite oxide and spinelle type composite oxides, precious metal catalyst and catalyst of transition metal oxide.Non-precious metal catalyst is active low, and the temperature of reacting required is higher, the easy inactivation of catalyst; Though noble metal catalyst is active high, costs an arm and a leg, component easily runs off when high temperature.Along with the development of new catalytic material, nano material has become the focus in the new process of exploitation catalysis.

The 4f track part of rare earth has weak coordination effect, especially Ce, Eu, Sm, La, Yb element, and the weak lewis acidity of rare earth oxide, and cryogenic absorption and activation c h bond are played an important role.Cerium oxide is the structure sensitive catalyst, its oxygen vacancies the crystal face that all depends on exposure with catalytic activity is provided.The surface of each crystal face of cerium oxide can be followed successively by: { 111}＜{ 110}＜{ 100}, wherein, { 100} is with { the 110} crystal face has the higher surface activity oxygen content.Adopt the preparation method of controllable appearance that cerium oxide is made nanostructured, the quantum effect on amplified material surface can make more active crystal face expose, thereby embody higher catalytic activity.As: adopt hard template method to prepare mesoporous cerium oxide; Adopt sol-gel process to prepare porous cerium oxide and cerium oxide nano pipe; Use the reverse microemulsion technology to prepare the cerium oxide particle of very small dimensions; By the sol-gel process of non-water, under the condition that surfactant exists, the nano-cerium oxide of large batch of synthetic different-shape.In addition, can improve the heat endurance of cerium oxide by synthetic methods such as surfactant auxiliary law, reverse microemulsion method, ultrasonic facture, spraying high temperature pyrolytic cracking (HTP)s; By other rare earth elements or the transition metal of mixing, also can make cerium oxide keep more catalytic activity crystal face at high temperature.The application of particular crystal plane nano-cerium oxide at present only limits to CO catalytic combustion, ethanol reforming reaction, and the application in the catalytic combustion that contains the oxygen volatile organic matter does not appear in the newspapers as yet.

Summary of the invention

The objective of the invention is to disclose a kind of oxygen-containing organic compound low-temperature catalytic burning method that is used for.This method is combustion catalyst with the cerium oxide nano-rod, and it is active high, no coupling product generates, do not cause secondary pollution, catalyst life is long, is specially adapted to complete catalytic combustion elimination oxygen-containing organic compound.

The invention provides a kind of low molecule oxygen-containing organic compound low-temperature catalytic burning method that is used for.Technology path is as follows:

In the presence of catalyst, adopt and bring reactor into as the air of oxidant, make to contain low molecule oxygen-containing organic compound completing combustion under the effect of catalyst, the molecule oxygen-containing organic compound be will hang down and carbon dioxide and water transformed into;

Reaction pressure is 0.1～1Mpa, preferred 0.1～0.5Mpa, especially 0.1Mpa, and near normal pressure, temperature is 100～350 ℃, is preferably 150～300 ℃;

Catalyst consumption, must be enough to make low molecule oxygen-containing organic compound existing under the situation at air, change into carbon dioxide and water, generally speaking, the concentration of oxygen-containing organic compound is 0.05～5vol% in the waste gas of low molecule oxygen-containing organic compound, and every gram catalyst treatment exhausted air quantity is 10～30L per hour.

This method is used cerium oxide nano-rod catalyst, its preparation method adopt at present disclosed method (document Journal of Catalysis.2005,229:206-212).

Adopt method of the present invention, as oxidant, under lower reaction temperature, in the presence of catalyst, can long-term and stably the oxygen-containing organic compound in the waste gas be transformed into carbon dioxide and water with air, activity of such catalysts does not reduce.

Catalyst provided by the invention has characteristics such as preparation technology is simple, cheap, catalytic activity is high, the life-span is long; Technology path is convenient and practical, and the catalytic combustion that can be widely used in the low molecule oxygen-containing organic compound pollutant in papermaking, pharmacy, process hides, washing and the chemical industry waste gas is eliminated.

The specific embodiment

Embodiment 1

With 2.6gCeCl ₃7H ₂Cerium salt and the 80ml deionized water of O are configured to certain density salting liquid, add a certain amount of NaOH solid again, be mixed with mixed solution (30% mass fraction), use magneton agitator vigorous stirring after half an hour, packing into has in the teflon-lined crystallizing kettle, then 120 ℃ of following static crystallization 48 hours, be cooled to room temperature after, with the deionized water filtration washing up to neutrality, again with the rinsing of 100ml absolute ethyl alcohol.Place 60 ℃ of baking ovens at last dry 12 hours, and after 350 ℃ of roastings, got pressed powder.Confirm that through X-ray diffracting spectrum pressed powder is the cerium oxide of fluorite structure; The TEM transmission electron microscope observation can confirm that the cerium oxide pressed powder that is synthesized is the nano bar-shape structure, and diameter 15 nanometers are more than length 350 nanometers.

The catalyst activity evaluation is carried out on fixed bed reactors.Unstripped gas carries out at the test of the catalytic combustion activity on catalyst normal pressure in the quartzy microreactor of U-shaped (internal diameter 3mm), and catalyst consumption is 80mg.Liquid phase ethyl acetate adopts 100 serial KDS101 type micro-injection pumps of U.S. Stoelting company to inject vaporizer (electrical heating) and vaporizes, and fully mixes with air afterwards, enters the reaction gas circuit again.Air mass flow adopts mass flowmenter control, and the concentration of raw material adopts micro-injection pump control.The triple purified treatment of process (active carbon, discolour silica gel and 5A molecular sieve) were to remove the impurity of a small amount of influence reaction in the air before air entered the reaction gas circuit.Reactor outlet gas is by the gas-chromatography on-line analysis of equipment fid detector.The method of reactor tail gas sample analysis is on given temperature, keeps and reacts half an hour, gets sample three times.The ethyl acetate conversion data is three mean values of analyzing.Ethyl acetate concentration is controlled at 0.05vol%, and the amount that every gram catalyst is per hour handled waste gas is 30L, is 340m/h through the gas line speed of reactor.The conversion ratio of ethyl acetate sees Table 1 under different temperatures.By table 1 as seen, the conversion temperature of ethyl acetate 90% is lower than 260 ℃ on the cerium oxide nano-rod catalyst, and its activity can be compared U.S. with noble metal.

Embodiment 2

The cerium oxide nano-rod catalyst that adopts embodiment 1 to make is a reactant with ethanol, and reaction unit and method are identical with embodiment 1.Ethanol conversion sees Table 1 under different temperatures, and by table 1 as seen, the conversion temperature of 90% ethanol is lower than 225 ℃ on the cerium oxide nano-rod catalyst, and its activity can be compared U.S. with noble metal.

Embodiment 3

The cerium oxide nano-rod catalyst that adopts embodiment 1 to make is a reactant with acetone, and reaction unit and method are identical with embodiment 1.The conversion ratio of acetone sees Table 1 under different temperatures.By table 1 as seen, 90% acetone conversion temperature is lower than 275 ℃ on the cerium oxide nano-rod catalyst.

Embodiment 4

Adopting reaction unit and the reaction condition of embodiment 1, is reactant with ethyl acetate, and fixation response time is 300 ℃, investigates the ethyl acetate conversion ratio over time.The results are shown in Table 2.By table 2 result as can be known, the cerium oxide nano-rod catalyst was stable in 1600 minutes.

Embodiment 5

Adopt embodiment 1 reaction unit, catalyst consumption is 80mg, and ethyl acetate concentration is controlled at 0.05vol%, changes the air inflow of reactor, and the exhaust-gas treatment amount that makes every gram catalyst is 40L, 50L, 60L.Under the condition of various inlet amount, the conversion ratio of ethyl acetate sees Table 3 under different temperatures.

Table 3 fruit shows that exhaust-gas treatment amount hourly can be up to the 50L/g catalyst down at 300 ℃ in the cerium oxide nano-rod catalysis, and this commercial Application for catalyst is very crucial and important beyond doubt.

The catalytic combustion of table 1 low molecule oxygen-containing organic compound on the cerium oxide nano-rod catalyst

Table 2 is ethyl acetate catalytic combustion stability test result on the cerium oxide nano-rod catalyst

Table 3 in air inflow on the cerium oxide nano-rod catalyst to the influence of ethyl acetate conversion ratio

Claims (2)

1. one kind is used for low molecule oxygen-containing organic compound low-temperature catalytic burning method.This method is a combustion catalyst with the cerium oxide nano-rod, is oxidant with the air, under the condition of normal pressure and heating, makes low molecule oxygen-containing organic compound completing combustion transform into carbon dioxide and water.

Described catalytic combustion, its reaction pressure are 0.1～1Mpa, preferred 0.1～0.5Mpa, especially 0.1Mpa, and near normal pressure, temperature is 100～350 ℃, is preferably 150～300 ℃;

Catalyst consumption, must be enough to make low molecule oxygen-containing organic compound existing under the situation at air, change into carbon dioxide and water, generally speaking, the concentration of oxygen-containing organic compound is 0.05～5vol% in the waste gas of low molecule oxygen-containing organic compound, and every gram catalyst treatment exhausted air quantity is 10～30L per hour.

2. according to claim 1, the method that is used for the low molecule oxygen-containing organic compound low-temperature catalytic burning elimination of effumability can be widely used in the low-temperature catalytic burning elimination of the low molecule oxygen-containing organic compound of industrial waste gas effumability.