CN102824909B - Catalyst for low-temperature catalytic combustion of volatile organic compounds and preparation method thereof - Google Patents

Abstract

The invention discloses a catalyst for low-temperature catalytic combustion of volatile organic compounds and a preparation method thereof, belonging to the technical fields of chemical catalyst and preparation technology thereof. The catalyst contains, by mass percent, 0.1 to 1 % of an active ingredient Pb, 74 to 99.4 % of a carrier Al2O3 and 0.5 to 25% of an auxiliary agent RE2O3, wherein a specific surface area of a composite oxide RE2O3- Al2O3 is 80 to 326 m<2>/g. The catalyst provided by the invention is simple in preparation technology, easy to produce in large scale, and has a very high catalytic activity for low-temperature complete oxidation reactions of benzene, toluene, xylene, ethyl acetate, ethanol and propane. Provided is a novel and high-efficiency catalyst which can be used for purification treatment of the volatile organic compounds in fields of industrial exhaust or indoor pollution.

Description

A kind of low-temperature catalytic combustion volatility organic matter Catalysts and its preparation method

Technical field

The invention belongs to chemical catalyst and preparing technical field thereof, be specifically related to a kind of low-temperature catalytic combustion volatility organic matter Catalysts and its preparation method.

Background technology

Under volatile organic matter (Volatile Organic Compounds, be called for short VOCs) refers to normal temperature, saturated vapor pressure is greater than 70Pa, and under normal pressure, boiling point is lower than the organic compound of 260 DEG C.Mainly comprise aromatic hydrocarbon, aliphatic hydrocarbon, halogenated hydrocarbons, oxygen-containing hydrocarbon, terpene hydrocarbon, alcohol, aldehyde, ketone and ester etc.They are petrochemical industries, pharmacy, print, major pollutants in the industry discharging waste gas such as to spray paint.This type organic mostly has toxicity and with stench, part can also be carcinogenic, and most VOCs has destruction to ozone layer.Traditional organic waste-gas purification method has absorption method, condensation method and direct combustion method etc., but they easily produce the restriction that secondary pollution, energy consumption are large, be subject to organic exhaust gas concentration and temperature.And catalytic combustion technology is that VOCs is completely oxidized to carbon dioxide and water, it is low that the method has initiation temperature, consuming little energy; Applied widely, almost can process all VOCs; The pollutants such as NOx can not be generated, non-secondary pollution; Equipment volume is little; Conversion ratio is high; Start energy consumption low, and the even advantage such as output heat energy can be reclaimed, become a kind of main method of purifying VOCs.The currently used catalyst of the method mostly is loaded noble metal catalyst, as ((1) the Catal Today such as Pt, Pd, Ru, Au, 1999,54:81 (2) Appl Catal B, 2012,111-112:218 (3) Chem Eng J, 2012,180:46) these loaded noble metal catalysts have low, the active high advantage of initiation temperature, but there is the shortcomings such as expensive, less stable, anti-poisoning capability are low simultaneously, make it apply and receive certain restriction ((4) Chem Lett, 1999,8:801 (5) J Catal, 2005,232:96).What research showed rare earth and oxide thereof adds the activity that can improve catalyst, the heat endurance, the sulfur resistive improving catalyst, anti-plumbous ability ((6) the Appl Catal B that improve catalyst, 2009,88:305 (7) J Alloy Compd, 2004,374:387).

Summary of the invention

The object of the present invention is to provide a kind of low-temperature catalytic combustion volatility organic matter Catalysts and its preparation method, catalyst preparation process of the present invention is simple, easy amplification is produced, to benzene,toluene,xylene, ethyl acetate, ethanol, propane low temperature complete oxidation, there is very high catalytic activity, be a kind of novel, efficient catalyst, can be used for the volatile organic matter purified treatment of the aspect such as industrial tail gas or indoor pollution.

For achieving the above object, the present invention adopts following technical scheme:

A kind of low-temperature catalytic combustion volatility organic matter catalyst, containing active component Pd, carrier A l ₂o ₃and auxiliary agent RE ₂o ₃, the mass percent of each component is: active component Pd 0.1 ~ 1%, auxiliary agent RE ₂o ₃0.5 ~ 25%, carrier A l ₂o ₃74 ~ 99.4%.

Described auxiliary agent RE ₂o ₃for Nd ₂o ₃, Eu ₂o ₃, Gd ₂o ₃, Yb ₂o ₃, Lu ₂o ₃in one or more mixture.With the addition of the Al after rare-earth additive ₂o ₃carrier specific area is 80 ~ 326m ²/ g.

The crystallite dimension of described active component Pd is 1 ~ 50nm.

A kind of method preparing low-temperature catalytic combustion volatility organic matter catalyst as above comprises the following steps:

(1) aluminium hydroxide and rare-earth hydroxide mixture is prepared by the method for co-precipitation;

(2) mixture step (1) obtained is 80 ~ 120 DEG C of dryings, 500 ~ 900 DEG C of roastings in air atmosphere, obtain RE ₂o ₃-Al ₂o ₃composite oxides;

(3) precursor solution of carrier incipient impregnation active component step (2) obtained, at 50 ~ 120 DEG C after drying in 500 ~ 900 DEG C of roastings.

The presoma of active component described in step (3) is the palladium metal inorganic salts-palladium nitrate of solubility.

Beneficial effect of the present invention: catalyst of the present invention has very high low-temperature catalytic activity to the catalyst combustion reaction of volatile organic matter as benzene,toluene,xylene, hydro carbons, alcohol, aldehyde, ether, ester etc., and preparation technology is simple, compared with common loaded noble metal catalyst, its activity is more excellent.This kind of catalyst is also expected to for other volatile organic matter in air as the catalytic combustion elimination of halogenated hydrocarbons, ketone etc.

Accompanying drawing explanation

Fig. 1 is the TEM figure of catalyst in embodiment 2.

Fig. 2 be in embodiment 3 and comparative example 1 catalyst to benzene catalyst combustion reaction conversion rate curve.

Detailed description of the invention

Below by by embodiment and comparative example, the catalyst to this invention is described further, but embodiments of the present invention are not limited to following embodiment.

Technical scheme of the present invention is as follows:

Low-temperature catalytic combustion volatility organic matter catalyst provided by the present invention, with precious metal palladium nano particle (1 ~ 50nm) for active component, with Al ₂o ₃for carrier, and rare earth RE ₂o ₃for auxiliary agent, RE ₂o ₃-Al ₂o ₃the specific area of composite oxides is 80 ~ 326m ²/ g.Wherein in catalyst, palladium accounts for 0.1 ~ 1%, RE ₂o ₃accounting for percentage by weight is 0.5 ~ 25%, carrier A l ₂o ₃accounting for percentage by weight is 74 ~ 99.4%.

The preparation method of catalyst of the present invention, is characterized in that: the Al that with the addition of rare-earth additive with coprecipitation preparation ₂o ₃carrier, RE ₂o ₃-Al ₂o ₃it is 80 ~ 326m that complex oxide surface amasss ²/ g.With equi-volume impregnating load active component palladium, palladium particle size is made to be 1 ~ 50nm.Catalyst preparation step comprises successively:

(1) aluminium hydroxide and rare-earth hydroxide mixture is prepared by the method for co-precipitation;

(2) by hydroxide obtained above 80 ~ 120 DEG C of dryings, 500 ~ 900 DEG C of roastings in air atmosphere, RE is obtained ₂o ₃-Al ₂o ₃composite oxides;

(3) by the precursor solution of composite oxides incipient impregnation active component obtained above, under 50 ~ 120 DEG C of substep conditions after drying in 500 ~ 900 DEG C of roastings.

In the preparation method of above-mentioned catalyst, the described active component presoma of step (3) is the palladium metal inorganic salts of solubility, preferred palladium nitrate.

embodiment 1

Take the Al (NO of 56.2690g ₃) ₃9H ₂nd (the NO of O and 3.2876g ₃) ₃6H ₂o is placed in conical flask, adds water to 200ml, after salt dissolves completely, ammoniacal liquor to the solution PH adding 28% under electric stirring condition is 8 ~ 10, continue to stir after 1h, sediment through standing, centrifugal, 120 DEG C of baking 12h, after in Muffle furnace air 800 DEG C of roasting 4h obtain composite oxides.The specific area recording composite oxides with physical adsorption appearance (Micromeritics ASAP 2020) is 186.8 m ²/ g.

Then, grinding is sieved, and gets 30 ~ 80 order composite oxide carriers, adopts equi-volume impregnating load quality mark to be the Pd of 0.5%.Detailed process is: get certain volume Pd solution impregnating carrier, stir 5min, with ultrasonic echography 10 min, after in baking oven 50 DEG C dry 0.5h, 80 DEG C are dried 0.5h, and 100 DEG C are dried 12h, proceed to Muffle furnace subsequently, 800 DEG C of roasting 4h in air atmosphere, grinding is sieved, and obtains catalyst.

In fixed bed reactors, evaluate catalytic combustion properties, catalyst amount 0.1g, air speed is 22000h ^-1, reaction gas is 500ppm C ₆h ₆, 20%O ₂, all the other are N ₂.In course of reaction, the programming rate of beds is 5 DEG C/min, adopts GC-9560 type gas chromatograph to carry out on-line analysis.Result shows, when reaction temperature is 200,250,300,350,400,450,500 DEG C, the conversion ratio of benzene is respectively 3.85,89.67,99.92,100,100,100 and 100%.

embodiment 2

RE ₂o ₃-Al ₂o ₃the preparation method of composite oxides and the mode of loading of precious metals pd, with embodiment 1, are the Gd (NO of 0.5149g unlike added rare earth nitrades ₃) ₃6H ₂o, the sintering temperature of the oxide after complex hydroxide and load P d is 600 DEG C.

The specific area recording composite oxides with physical adsorption appearance is 186.8 m ²/ g.Transmission electron microscope (as accompanying drawing 1) shows that the size of precious metal palladium particle in catalyst is about 6nm.

The activity rating method of catalyst is with embodiment 1.Experimental result shows, when reaction temperature is 200,250,300,350,400,450,500 DEG C, the conversion ratio of benzene is respectively 10.85,64.89,99.65,99.97,100,100 and 100%.

embodiment 3

RE ₂o ₃-Al ₂o ₃the preparation method of composite oxides and the mode of loading of precious metals pd, with embodiment 1, are the Yb (NO of 0.7007g unlike added rare earth nitrades ₃) ₃6H ₂o, the sintering temperature of the oxide after complex hydroxide and load P d is 600 DEG C, and the load capacity of Pd is 0.1%.The specific area recording composite oxides with physical adsorption appearance is 225.8 m ²/ g.

The activity rating method of catalyst is with embodiment 1.Result shows, when reaction temperature is 200,247,300,348,401,450,503 DEG C, the conversion ratio of benzene is respectively 0,10.63,98.09,100,100,100 and 100%.

comparative example 1

Al ₂o ₃preparation method and the mode of loading of precious metals pd and load capacity with embodiment 3, difference does not add rare earth nitrades.Experiment gained Al ₂o ₃specific area be 235.2 m ²/ g.

As a comparison, by the Pd/Al of gained above ₂o ₃catalyst takes 0.1g, is 22000h in air speed ^-1, benzene concentration is under the condition of 500ppm, and the catalyst combustion reaction testing its benzene is active.Result shows, when temperature is 203,255,305,356,406,452,500 DEG C, the conversion ratio of benzene is respectively 0,19.09,67.02,98.15,99.38,99.96 and 99.97%.

embodiment 4

RE ₂o ₃-Al ₂o ₃the preparation method of composite oxides and the mode of loading of precious metals pd, with embodiment 1, are the Lu (NO of 0.3518g unlike added rare earth nitrades ₃) ₃6H ₂yb (the NO of O and 0.3503g ₃) ₃6H ₂o, the sintering temperature of the oxide after complex hydroxide and load P d is 700 DEG C, and in catalyst, the load capacity of Pd is 0.1%.The specific area of gained composite oxides is 223.4 m ²/ g.

The activity rating method of catalyst is with embodiment 1.Result shows, when temperature is 203,256,303,352,400,450,500 DEG C, the conversion ratio of benzene is respectively 0,13.47,93.68,99.81,100,100 and 100%.

embodiment 5

RE ₂o ₃-Al ₂o ₃the preparation method of composite oxides and the mode of loading of precious metals pd, with embodiment 1, are the Lu (NO of 0.2345g unlike added rare earth nitrades ₃) ₃6H ₂yb (the NO of O, 0.2336g ₃) ₃6H ₂o and 0.2257g Gd (NO ₃) ₃6H ₂the mixture of O, the sintering temperature of the oxide after complex hydroxide and load P d is 700 DEG C, and in catalyst, the load capacity of Pd is 0.1%.The specific area of gained composite oxides is 247.2 m ²/ g.

The activity rating method of catalyst is with embodiment 1.Result shows, when temperature is 201,247,299,350,400,450,500 DEG C, the conversion ratio of benzene is respectively 0,10.63,98.69,100,100,100 and 100%.

The foregoing is only preferred embodiment of the present invention, all equalizations done according to the present patent application the scope of the claims change and modify, and all should belong to covering scope of the present invention.

Claims (1)

1. a preparation method for low-temperature catalytic combustion volatility organic matter catalyst, described catalyst contains active component Pd, carrier A l ₂o ₃and auxiliary agent RE ₂o ₃, it is characterized in that: in described catalyst, the mass percent of each component is: active component Pd 0.1 ~ 1%, auxiliary agent RE ₂o ₃0.5 ~ 25%, carrier A l ₂o ₃74 ~ 99.4%;

Described auxiliary agent RE ₂o ₃for Nd ₂o ₃, Eu ₂o ₃, Gd ₂o ₃, Lu ₂o ₃in one or more mixture;

With the addition of rare-earth additive RE ₂o ₃after Al ₂o ₃carrier specific area is 80 ~ 326m ²/ g;

The crystallite dimension of described active component Pd is 1 ~ 50nm;

Preparation method comprises the following steps:

(1) aluminium hydroxide and rare-earth hydroxide mixture is prepared by the method for co-precipitation;

(2) mixture step (1) obtained is 80 ~ 120 DEG C of dryings, 500 ~ 900 DEG C of roastings in air atmosphere, obtain RE ₂o ₃-Al ₂o ₃composite oxides;

(3) precursor solution of carrier incipient impregnation active component step (2) obtained, at 50 ~ 120 DEG C after drying in 500 ~ 900 DEG C of roastings;

The presoma of active component described in step (3) is the palladium metal inorganic salts of solubility;

The palladium metal inorganic salts of described solubility are palladium nitrate.