US Patent 7288131 Porous honeycomb structure

A porous honeycomb structure includes: a plurality of partition walls containing cordierite as a main component and constituted of a porous ceramic having a porosity of 55 to 75% and an average pore diameter of 15 to 35 μm, wherein the partition walls have a pore distribution represented by the following condition formula (1):Lr>0.3×P/100+0.91,  (1)“in the above condition formula (1), Lr means an average developed length ratio, and P means a porosity obtained from a total pore volume measured by a mercury press-in type porosimeter, assuming that a true specific gravity of cordierite is 2.52 g/cc.”