Thermal shock resistant soot filter

1. A ceramic honeycomb filter comprising a porous ceramic honeycomb body having an inlet end and outlet end connected by adjacent inlet and outlet channels that extend from the inlet end to the outlet end of the ceramic body, the inlet and outlet channels being defined by a plurality of interlaced thin gas filtering porous partition walls between the inlet and outlet channels and by ceramic plugs, such that the inlet channel has an inlet ceramic plug at the outlet end of the ceramic body and the outlet channel has an outlet ceramic plug at the inlet end of the ceramic body such that a fluid when entering the inlet end must pass through partition walls to exit the outlet end, wherein, within the ceramic honeycomb body there is a heat absorbing material that undergoes a reversible phase change that absorbs heat energy, said absorbing material being contained within a shell that prevents flow of the heat absorbing material within the porous honeycomb ceramic body.

2. The ceramic honeycomb filter of claim 1 , wherein the honeycomb is comprised of an acicular ceramic.

3. The ceramic honeycomb filter of claim 2 , wherein the acicular ceramic is acicular mullite.

4. The ceramic honeycomb filter of claim 1 , wherein the reversible phase change is melting from a solid to a liquid.

5. The ceramic honeycomb filter of claim 1 , wherein the heat absorbing material is a metal.

6. The ceramic honeycomb filter of claim 5 , wherein the metal is aluminum, tin, copper, an alloy of claim 5 , or mixture of the aforementioned.

7. The ceramic honeycomb filter of claim 1 , wherein the heat absorbing material is a metal encased in a shell.

8. The ceramic honeycomb filter of claim 1 , wherein the shell is a ceramic or metal with a melting temperature at least 200° C. greater than the temperature where the heat absorbing material undergoes the reversible phase change.

9. The ceramic honeycomb filter of claim 8 , wherein the heat absorbing material is a metal and the shell is an oxide of said metal.

10. The ceramic honeycomb filter of claim 9 , wherein the metal is aluminum, copper, tin, alloy of any one of the aforementioned, or mixture of any of the aforementioned.

11. The ceramic honeycomb filter of claim 10 , wherein the metal is aluminum or alloy thereof.

12. The ceramic honeycomb filter of claim 1 , wherein the phase change of the heat absorbing material occurs at a phase change temperature of at least about 525° C. to at most about 1000° C.

13. The ceramic honeycomb filter of claim 12 , wherein the phase change temperature is at least about 550° C.

14. The ceramic honeycomb filter of claim 13 , wherein the phase change temperature is at most about 800° C.

15. A method of filtering diesel soot comprising,

i) providing a ceramic honeycomb filter having, within the ceramic honeycomb filter, a heat absorbing material that undergoes a reversible phase change that absorbs heat energy, ii) passing, diesel exhaust through the said ceramic honeycomb filter such that soot in said exhaust is captured by said filter, and iii) heating the ceramic honeycomb filter sufficiently such that the Diesel soot combusts wherein the heat absorbing material changes phase such that a portion of the heat generated from combustion of said soot is absorbed by said change of phase.

16. The method of claim 15 , wherein the heat absorbing material is a metal.

17. The method of claim 16 , wherein the heat absorbing material is a metal encased in shell having a melting temperature at least 200° C. higher than the temperature where the heat absorbing material undergoes the reversible phase change.

18. The method of claim 16 , wherein the metal is aluminum or alloy thereof.

19. The method of either claim 15 , wherein the heat absorbing material is encased in a shell.

20. The method of claim 19 , wherein the shell is a ceramic or metal with a melting temperature at least 200° C. greater than the temperature where the heat absorbing material undergoes the reversible phase change.