CATALYZED CERAMIC CANDLE FILTER AND METHOD OF CLEANING PROCESS OFF- OR EXHAUST GASES

Abstract

Ceramic candle filter and use of the filter in the removal of particulate matter in form of soot, ash, metals and metal compounds, together with hydrocarbons and optionally nitrogen oxides being present in process off-gas or engine exhaust gas, wherein a noble metal comprising catalyst is arranged on the permeation side of the filter and/or on the dispersion side of the filter and/or within wall of the filter, said noble metal comprising catalyst contains a noble metal in an amount of between 20 and 1000 ppm/weight of the filter.

Claims

1. A ceramic candle filter, wherein a noble metal comprising catalyst is arranged on the permeation side of the filter and/or on the dispersion side of the filter and/or within wall of the filter, said noble metal comprising catalyst contains a noble metal in a total amount of between 20 and 1000 ppm/weight of the filter.

2. The ceramic candle filter of claim 1, wherein the noble metal is palladium and/or platinum.

3. The ceramic candle filter of claim 1, wherein the noble metal comprising catalyst further comprises a vanadium oxide and titania.

4. The ceramic candle filter according to claim 1, wherein the ceramic material of the filter is selected from the group of silica-aluminate, calcium-magnesium-silicates, calcium-silicates fibers, or a mixture thereof.

5. The ceramic candle filter according to claim 4, wherein the ceramic material of the filter consists of bio-soluble fibres selected from the group of calcium-magnesium-silicates.

6. A method for the removal of particulate matter in form of soot, ash, metals and metal compounds, together with hydrocarbons and carbon monoxide being present in process off-gas or engine exhaust gas, comprising the steps of passing the off-gas or the exhaust gas through a ceramic candle filter and capturing the particulate matter; reducing amounts of soot in the particulate matter captured on dispersion side of the filter and reducing amounts of hydrocarbons in the off- or exhaust gas by contact with an oxidation catalyst being arranged on and/or within wall of the filter, wherein said oxidation catalyst comprises one or more noble metals in total amount of between 20 and 1000 ppm/weight of the filter.

7. The method of claim 6, wherein the one or more noble metals of the oxidation catalyst are palladium and/or platinum.

8. The method of claim 6, wherein oxidation catalyst further comprises a vanadium oxide and titania.

9. The method according to claim 6, wherein the ceramic material of the filter is selected from silica-aluminate, calcium-magnesium-silicates, calcium-silicates fibers, or mixtures thereof.

10. The method according to claim 6, wherein the ceramic material of the filter comprises bio-soluble fibres selected from the group of calcium-magnesium-silicates.

Description

EXAMPLE 1

[0033] The following example illustrates the performance obtainable with a ceramic candle filter prepared from calcium-magnesium-silicate fibres with a length of 3 m and wall thickness of 20 mm. The filter was coated within the wall with the V/Ti catalyst containing 1.26 wt % V and 2.36 wt % Ti calculated on the total weight of the filter. The porosity of the coated filter was 83%. The filter was tested in the oxidation of toluene in an inlet gas containing 40 ppm, dry toluene, 19% vol O.sub.2, 8% vol H.sub.2O.

[0034] Toluene oxidation on a V/Ti coated filter

TABLE-US-00001 Conversion Temp. Face vel. of Toluene CO, out ° C. m/min % ppm, wet 220 1.28 96 16 240 1.34 98 35

[0035] As apparent from the table above, 85% of toluene was converted at 240° C. The CO emission at the same temperature was equal to 35 ppm, wet.

EXAMPLE 2

[0036] The following example illustrates the CO oxidation performance of the ceramic candle filter of Example 1, but additionally coated with 36 ppm Pd. The tests were conducted with a gas containing around 150 ppm, wet CO, 19% O.sub.2 and 8% H.sub.2O.

TABLE-US-00002 Conversion Temp. Face vel. CO, in CO, out of CO ° C. m/min ppm, wet ppm, wet % 220 1.28 148 36.5 75 240 1.35 157 4 97

[0037] At 240° C., 97% of the CO was oxidized to CO.sub.2.

[0038] By combining the performance of the ceramic candle filter reported in EXAMPLE 1 and EXAMPLE 2, it is possible to conclude that only 1 ppm CO is emitted by a candle filter catalyzed with a V/Ti catalyst on the dispersion side and a Pd/V/Ti catalyst on the permeation side.