A plugged honeycomb structure including: a pillar-shaped honeycomb structure body having porous partition walls made of a material including silicon carbide, and plugging portions, wherein a porosity of the partition walls is from 42 to 52%, a thickness of the partition walls is from 0.15 to 0.36 mm, a ratio of a volume of pores having pore diameters of 10 m or less to a total pore volume of the partition walls is 41% or less, a ratio of a volume of pores having pore diameters in a range of 18 to 36 m to the total pore volume is 10% or less, the pore diameter indicating a maximum value of the log differential pore volume is in a range of 10 to 16 m, and a half-value width of a peak including the maximum value of the log differential pore volume is 5 m or less.

A plugged honeycomb structure including: a pillar-shaped honeycomb structure body having porous partition walls made of a material including silicon carbide, and plugging portions, wherein a porosity of the partition walls is from 42 to 52%, a thickness of the partition walls is from 0.15 to 0.36 mm, a ratio of a volume of pores having pore diameters of 10 m or less to a total pore volume of the partition walls is 41% or less, a ratio of a volume of pores having pore diameters in a range of 18 to 36 m to the total pore volume is 10% or less, the pore diameter indicating a maximum value of the log differential pore volume is in a range of 10 to 16 m, and a half-value width of a peak including the maximum value of the log differential pore volume is 5 m or less.

A plugged honeycomb structure including: a pillar-shaped honeycomb structure body having porous partition walls made of a material including silicon carbide, and plugging portions, wherein a porosity of the partition walls is from 42 to 52%, a thickness of the partition walls is from 0.15 to 0.36 mm, a ratio of a volume of pores having pore diameters of 10 m or less to a total pore volume of the partition walls is 41% or less, a ratio of a volume of pores having pore diameters in a range of 18 to 36 m to the total pore volume is 10% or less, the pore diameter indicating a maximum value of the log differential pore volume is in a range of 10 to 16 m, and a half-value width of a peak including the maximum value of the log differential pore volume is 5 m or less.

A plugged honeycomb structure including: a pillar-shaped honeycomb structure body having porous partition walls made of a material including silicon carbide, and plugging portions, wherein a porosity of the partition walls is from 42 to 52%, a thickness of the partition walls is from 0.15 to 0.36 mm, a ratio of a volume of pores having pore diameters of 10 m or less to a total pore volume of the partition walls is 41% or less, a ratio of a volume of pores having pore diameters in a range of 18 to 36 m to the total pore volume is 10% or less, the pore diameter indicating a maximum value of the log differential pore volume is in a range of 10 to 16 m, and a half-value width of a peak including the maximum value of the log differential pore volume is 5 m or less.

Disclosed is a method for the decomposition of SiC or SiC-containing materials in which the reaction is guided exclusively via gaseous products for achieving a conversion which is as complete as possible. A preferred application is a recycling process for catalyst materials containing platinum metals on a carrier material made of silicon carbide (SiC). In the thermal process, the catalyst materials are freed from the carrier material, and then they can further be refined. (FIG. 1)

Disclosed is a method for the decomposition of SiC or SiC-containing materials in which the reaction is guided exclusively via gaseous products for achieving a conversion which is as complete as possible. A preferred application is a recycling process for catalyst materials containing platinum metals on a carrier material made of silicon carbide (SiC). In the thermal process, the catalyst materials are freed from the carrier material, and then they can further be refined. (FIG. 1)

The present invention relates to SiC nanostructures, including SiC nanopowder, SiC nanowires, and composites of SiC nanopowder and nanowires, which can be used as catalyst supports in membrane electrode assemblies and in fuel cells. The present invention also relates to composite catalyst supports comprising nanopowder and one or more inorganic nanowires for a membrane electrode assembly.

The present invention relates to SiC nanostructures, including SiC nanopowder, SiC nanowires, and composites of SiC nanopowder and nanowires, which can be used as catalyst supports in membrane electrode assemblies and in fuel cells. The present invention also relates to composite catalyst supports comprising nanopowder and one or more inorganic nanowires for a membrane electrode assembly.

A process of methane catalytic conversion produces olefins, aromatics, and hydrogen under oxygen-free, continuous flowing conditions. Such a process has little coke deposition and realizes atom-economic conversion. Under the conditions encountered in a fixed bed reactor (i.e. reaction temperature: 750-1200 C.; reaction pressure: atmospheric pressure; the weight hourly space velocity of feed gas: 1000-30000 ml/g/h; and fixed bed), conversion of methane is 8-50%. The selectivity of olefins is 30-90%. And selectivity of aromatics is 10-70%. The catalyst for this methane conversion has a SiO.sub.2-based matrix having active species that are formed by confining dopant metal atoms in the lattice of the matrix.

A process of methane catalytic conversion produces olefins, aromatics, and hydrogen under oxygen-free, continuous flowing conditions. Such a process has little coke deposition and realizes atom-economic conversion. Under the conditions encountered in a fixed bed reactor (i.e. reaction temperature: 750-1200 C.; reaction pressure: atmospheric pressure; the weight hourly space velocity of feed gas: 1000-30000 ml/g/h; and fixed bed), conversion of methane is 8-50%. The selectivity of olefins is 30-90%. And selectivity of aromatics is 10-70%. The catalyst for this methane conversion has a SiO.sub.2-based matrix having active species that are formed by confining dopant metal atoms in the lattice of the matrix.