DE10218336B4 - Process for the preparation of an adsorbent, adsorbent and its use - Google Patents

Abstract

Process for the preparation of a dimensionally stable in liquid media adsorbent powder rubber in the
a) liquid-containing powder rubber is pressed into moldings,
b) the moldings dried and
c) are then carbonized to dimensionally stable adsorbent.

Description

The The invention relates to a process for producing a liquid in media dimensionally stable adsorbent made of powdered rubber and the hereafter prepared adsorbents. Use find such produced Adsorbents in any application of adsorption, especially in wastewater treatment, drinking water treatment, air and water Gas cleaning and hydrocarbon and solvent recovery.

Carbonaceous adsorbents have large specific surface areas. Activated carbon, as an example of a carbonaceous adsorbent, has specific surface areas, typically between 800 and 1400 m ² / g. Such adsorbents are used for wastewater treatment, drinking water treatment, air and gas purification, coal hydrogen and solvent recovery and many other applications of adsorption.

at adsorption processes in the liquid phase and in the gas phase, activated carbon is typically used. Form activated carbons be made of a carbon carrier, for example, charcoal or coal, and a binder, For example, tar, pitch or water-based binders such as Strength, Molasses or polyvinyl alcohol, produced. Products and manufacturing processes for activated carbon are described in numerous patents.

That's how they teach DE 23 22 706 and the DE 38 34 743 Gas activation process, while the US 5,416,056 describes the chemical activation. The manufacturing processes involve elaborate thermal and / or chemical process steps up to the activation, in which the large surface area typical for adsorbents is created.

Around Applications in the field of adsorption in gaseous or liquid phase, which require a low pressure loss, to be able to meet mechanical loads Pellets in cylindrical shape with 1-4 mm diameter, used. Such adsorbent pellets are so far based on activated carbon, wherein the method at least an activation step, e.g. chemical activation or gas phase activation, at elevated Temperature includes. Both activation methods have disadvantages on. At the chemical activation must after the activation step the Aktivierungsreagenz be recovered consuming and for the gas phase activation are high temperatures of 800 to 1000 ° C and long residence times in the Activation furnace necessary. Both steps cause in a technical Plant high investment and operating costs.

at some gas phase applications, especially in the adsorption of Hydrocarbons on activated carbon, is the subsequent regeneration of the adsorbent required. The regeneration, or desorption, should preferably Completely expire, so that afterwards the original adsorption capacity of the unused Adsorbent is available. For the Desorption should be as possible little energy is spent. The according to the prior art available However, activated carbons have high residual loadings between 3 and 20 Wt .-% on.

In the DE 199 24 367 a process for the adsorption of organic compounds and adsorbents of powdered rubber, so-called. Powdered rubber, or latex-added carbon black is described. This powdery product is well suited for the setting of oil from the aqueous phase. However, for applications in which the adsorbent must be flowed through, it is not suitable because it tends to segregation or blocking and the pressure loss is too large. In addition, the product is due to its powdery consistency only limited storage and transportable.

Out WO 01/38229 is a method of water and wastewater Absorption is known in which as an absorbent partially vulcanized rubber, the filler may be used.

From the DE 4233 478 A1 a two-stage process for the purification of exhaust air or exhaust gas is known, in which in the second process stage as a adsorbent, a thermoplastic rubber is used. The thermoplastic rubber is coated or coated with a hydrophobic silica.

task The present invention was therefore that of the prior art to eliminate known disadvantages and a mechanically strong To provide adsorbent that is easy to manufacture and at the same time a big one specific surface has, so that high Adsorptionsbeladungen can be achieved. These The object is achieved by the method having the features of the claim 1 and the adsorbent prepared according to claim 1 15 solved. The other dependent claims show advantageous developments. In claim 18, the Use of the inventively prepared Adsorbent described.

• a) der Verpressung des flüssigkeitshaltigen Pulverkautschuks zu einem Formling,
• b) der Trocknung des Formlings und
• c) der anschließenden Carbonisierung zum formstabilen Adsorptionsmittel.

According to the invention, a method for Preparation of a dimensionally stable in liquid media adsorbent made of powdered rubber. This method is based on

• a) the compression of the liquid-containing powdered rubber into a molded article,
• b) the drying of the molding and
• c) the subsequent carbonation to a dimensionally stable adsorbent.

so produced adsorbents show excellent adsorption properties both in the liquid as well as the gas phase. Outstanding are the very good oil binding in the liquid phase as well as the good absorption capacity of hydrocarbons or their almost complete desorption in the gas phase. About that In addition, the inventive method a cost effective alternative to the known from the prior art method.

at The process uses a starting material which has a high specificity Surface has. This surface remains in the course of the process steps received or will be again made, therefore, a complex activation, as from the state The technique is known, usually can be omitted. That after the inventive method produced adsorbent is even with prolonged use in one liquid Medium dimensionally stable. The mechanical resistance to pressure loads is significantly increased. When flowing through shows the adsorbent compared to the powder form clearly lower pressure drops, in the range known Formaktivkohlen lie.

One Another advantage of the adsorbent according to the invention based on that these opposite the known from the prior art activated carbons a very high capacity and have a high proportion of macro- and mesopores. This Share allows an efficient mass transport through the adsorbent and at the same time reduces the likelihood of clogging the Pore structure through the adsorption of high molecular weight substances or by swelling processes. Especially for longer Transport paths in adsorbents larger dimension is a large proportion of macropores beneficial to a faster adsorption and an optionally desired Desorption to allow regeneration of the adsorber.

Opposite powders has the inventively prepared Adsorbents in the form of pellets have the advantage of a clear reduced pressure loss, which suggests a low flow resistance. Especially for gas phase applications but also for Liquid phase application is the low pressure loss of crucial importance. Likewise, the inventively produced Pellets better storage and transport ability.

In a variant of the method according to the invention undried powder rubber is used as starting material, having a water content between 70 and 90% by weight, preferably 80% by weight having. In this variant, the existing in the powder rubber Latex as a binder, other binders are not necessary.

Surprisingly could be shown that this still moist powder rubber without further pretreatment in a press to cylindrical, free-flowing pellets can be processed.

A another variant provides that as a starting material binder-containing Powder rubber is used. As binders are preferred water-based binders such as starch, molasses, polyvinyl alcohol or mixtures thereof used.

For the production Such binder-containing powder rubbers are two alternatives to disposal. In the first alternative, a suspension of soot particles or powdered rubber in aqueous Phase produced with the binder, then an agglomeration or precipitation carried out and finally the powdered rubber in a filter press to a liquid content Dehydrated from about 80 wt .-%. According to the second alternative, the powdered rubber is first dried, ground and only afterwards with mixed with the binder. The powder rubber can with the binder directly or with a mixture of binder and water intimately mixed and then the be supplied to further process steps.

in this connection was surprisingly found that dried powder rubber material in a Mixing apparatus, e.g. a Z-kneader, mixable with undiluted or diluted with water binder is. The mix thus prepared can be without further pretreatment process in a press into cylindrical, free-flowing pellets.

Preferably For example, the powder rubber used as a starting material has one Latex content of more than 5 wt .-%, and preferably of more than 10 Wt .-% on. It could be shown that the increase of the Latex content in the original Powder rubber has a positive influence on the mechanical strength of the adsorbent. At elevated Temperatures splits latex molecules which can then form a more stable grain composite.

Preferably, the compression in step a) in a die press, preferably in a Flat die press performed.

The Drying of the moldings is preferably carried out at a temperature between 70 and 150 ° C, especially preferably between 80 and 140 ° C. The drying is preferably carried out until, until the moldings have a water content of less than 1 wt .-%. The dried moldings already have a high abrasion hardness are however sensitive to Pressure.

Of the subsequent Carbonization step is carried out by means of a thermal treatment under inert gas atmosphere at temperatures between 120 and 750 ° C, more preferably between 140 and 650 ° C. It could be determined that such a thermal Treatment of the mechanical Fe strength of the adsorbent against pressure loads elevated.

It could be shown that a thermal treatment of both binder-containing as well as the binder-free moldings under inert gas atmosphere their mechanical strength against pressure loads once again clearly increased. at the heightened Temperature hardens the binder and the latex cleaves off molecules, resulting in a more stable Grain composite forms. In particular, a carbon skeleton is formed, which contributes significantly to the solidification of the moldings. Surprisingly, it was also shown be that the specific surface the Adsorberformkörper despite high binder levels in the mixture due to the thermal treatment could almost be restored.

Preferably The adsorbent may undergo additional activation become. Therefor can used the activation method known from the prior art be, e.g. by steam treatment at temperatures between 500 and 1000 ° C, preferably between 650 and 950 ° C over a Period of 1 to 6 hours. Partially so can the specific Surface of the Adsorbent be further increased.

Preferably are used as adsorbent pellets, preferably in cylindrical Mold with a diameter between 1 and 4 mm, made.

According to the present invention, an adsorbent prepared by the process of the present invention is also provided. An adsorbent prepared in this way, whether with or without additional binder, is dimensionally stable even after prolonged use in the liquid phase. It preferably has a specific surface area of more than 800 m ² / g, particularly preferably more than 1100 m ² / g. The ball-pan hardness of the adsorbent according to the invention is preferably more than 98% by weight, more preferably more than 99% by weight.

Especially advantageous is the high proportion of macro- and mesopores of Adsorberformkörper invention.

use finds the inventively prepared Adsorbents in any field of adsorption technology. Just as an example, here are the wastewater treatment, drinking water treatment, air and gas purification as well as hydrocarbon and solvent recovery called.

Based The following examples are intended to indicate the object according to the application be explained in more detail, without limiting it to these specific embodiments.

example 1

rubber powder with a latex content of 10% by weight is in the dehydrated, undried state (Water content about 80 wt .-%) in a die press to cylindrical Pellets pressed with 3 mm diameter. The pellets are placed in a drying oven 16 h at 80 ° C and 1 h at 105 ° C dried and then thermally treated in a rotary tube reactor. You will be with one Heating rate of 10 K / min under nitrogen to 500 ° C heated held at this temperature for one hour, and then on Ambient temperature cooled.

The thermal treatment has a yield of 80 wt .-%. The moldings produced in this way have a shaking density of 165 g / l, a ball-pan hardness of 98.9% by weight and a BET specific surface area of 850 m ² / g. The carbon tetrachloride activity as a measure of the adsorption capacity with respect to gas constituents is 75% by weight. As a result, the new adsorption agent has better adsorption capacities at a lower density and lower specific surface area than comparable molded activated carbons.

Example 2

Powder rubber material is dried to a residual water content of 1 wt .-% and then ground. The dusty powder rubber material is intimately mixed with four times the amount of molasses in a Z-kneader and then compressed in a flat die press to cylindrical pellets (2 and 3 mm diameter), the pellets produced are water contents of less than 1 wt .-% in a drying oven at maximum Dried at 105 ° C. Then the 3 mm pellets are added 500 ° C for 1 h Carbonized. The yield in the carbonation is 75 wt .-% (based on dry pellets).

By the carbonization decreases the density of the pellets by about 5%. Of the Ash content increases by about 25%. The butane working capacity (ASTM D 5228-92) quintupled from 0.44 to 2.44 g / 100 ml. The mechanical strength with respect. Pressure load is also increased. Unlike dried pellets are the carbonated pellets due to their water insolubility also for the use in the liquid Phase suitable.

Claims (18)

Process for producing a in liquid media dimensionally stable adsorbent powder rubber in the a) liquid-containing Powder rubber is pressed into moldings, b) the moldings dried and c) subsequently be carbonized to dimensionally stable adsorbent. Method according to claim 1, characterized in that that as starting material powder rubber with a water content from 70 to 90% by weight, preferably over 80 wt .-% is used. Method according to one of claims 1 or 2, characterized that used as starting material binder-containing powder rubber becomes. Method according to claim 3, characterized that as a binder starch, Molasses, polyvinyl alcohol or mixtures thereof Mi are used. Method according to one of claims 3 or 4, characterized that the binder-containing powder rubber from a suspension of soot particles or powdered rubber in aqueous Phase with the binder, subsequent agglomeration or precipitation as well drainage of the powder rubber is produced in a filter press. Method according to one of claims 3 or 4, characterized that the binder-containing powder rubber by mixing dried and ground powdered rubber and the binder will be produced. Method according to one of claims 1 to 6, characterized the powder rubber used as starting material has a latex content of more than 5 wt .-%, preferably more than 10 wt .-%. Method according to one of claims 1 to 7, characterized that the compression is carried out in a die press. Method according to one of claims 1 to 8, characterized that the drying at a temperature between 70 and 150 ° C, preferably between 80 and 140 ° C carried out becomes. Method according to one of claims 1 to 9, characterized that the moldings or the adsorbent after drying have a water content of less than 1 wt .-%. Method according to one of claims 1 to 10, characterized that the carbonization under inert gas atmosphere at a temperature between 120 and 750 ° C, preferably between 140 and 650 ° C he follows. Method according to one of claims 1 to 11, characterized that the adsorbent of an additional activation by Steam treatment at temperatures between 500 and 1000 ° C over a Period of 1 to 6 h is subjected. Method according to claim 12, characterized in that that extra Activation by steam treatment at temperatures between 650 and 950 ° C over one Period of 1 to 6 h takes place. Method according to one of claims 1 to 13, characterized that the adsorbent in the form of pellets of cylindrical shape will be produced. Adsorbent produced by the process according to at least one of the claims 1 to 14. Adsorbent according to claim 15, characterized in that the adsorbent has a specific surface area of over 800 m ² / g, preferably about 1100 m ² / g. Adsorbent according to one of claims 15 or 16, characterized in that the adsorbent has a ball-pan hardness of more than 98 wt .-%, preferably more than 99 wt .-%. Use of the method according to at least one of the claims 1 to 14 produced adsorbent for wastewater and drinking water treatment, exhaust gas purification and solvent recovery.