A carbon black is provided which is useful as an electrocatalyst carrier. The carbon black has a DBP oil absorption of 170 to 300 cm.sup.3/100 g, a specific surface area as measured by a BET method of 250 to 400 m.sup.2/g, a primary particle diameter value of 10 to 17 nm, and a total volume of open pores at the surface which have a pore radius of 10 to 30 nm of 0.40 to 2.0 cm.sup.3/g. The electrocatalyst can be used in electrochemical devices such as solid polymer electrolyte fuel cells.

A hydrogenolysis catalyst that possesses high hydrogenolysis performance at low temperatures and during the debenzylation reaction of a compound wherein a benzyl group combines with a nitrogen atom, which is difficult for conventional catalysts. The catalyst comprises (a) a component comprising at least one compound selected from the group consisting of palladium oxide, palladium oxide monohydrate, and palladium hydroxide wherein the oxidation of palladium is divalent, and (b) a component comprising at least one element selected from the group consisting of Pt, Ru, Rh, Ir and Au, carried on a non-organic porous substance.

There is described a catalyst for purification of exhaust gases containing nitrogen oxides wherein oxygen is co-existent in excess of a stoichiometric amount, characterized in that a coprecipitated mixed oxide of copper and tin is loaded on a carrier composed of at least one type selected from the group consisting of crystalline aluminosilicate, aluminogallosilicate and gallosilicate, or the coprecipitated mixed oxide of copper and tin and further at least one noble metal selected from the group consisting of platinum, palladium, rhodium, iridium, ruthenium, silver and gold are co-loaded thereon. This invention provides a lean NOx purification catalyst having high NOx purification performance and markedly increased durability over a wide temperature range.

A catalyst for purification of exhaust gases containing nitrogen oxides in the co-existence of oxygen in excess of stoichiometric amount, which catalyst comprises (a) a carrier consisting of a crystalline metallosilicate whose anhydrous state is represented by the following chemical formula wherein R is at least one cation having a valence n; x, y and z are, respectively, mole fractions of different metal elements M, Al and Si present as a tetrahedral oxide in the skeletal structure; M is at least one metal selected from the group consisting of Ga, Fe, Y and rare earth elements; X+Y+z=1,000, x.gtoreq.0, y>0 and 0.990 .gtoreq.z.gtoreq.0.882, and (b) a co-precipitated compound oxide of copper and gallium, supported on said carrier in a dispersed state. The present invention provides a catalyst for NOx abatement which can be used for treatment of exhaust gases containing nitrogen oxides in the co-existence of oxygen in excess of stoichiometric amount and which has high NOx abatement activity and very high durability over a wide temperature range.

A catalyst for oxidizing a carbon-containing compound comprising a composite oxide powder composed of 4 to 19% by weight of silica, 3 to 10% by weight of boria, and the balance alumina, and palladium in an amount of 3 to 100 g per 1 liter of the powder carried on the composite powder, and a method for producing such a catalyst are described. The composite oxide is thermally stable and prevents reduction of palladium oxide, and the catalyst can be used for an extended period high temperatures.