Abstract: A carbon black is provided which is useful as an electrocatalyst carrier. The carbon black has a DBP oil absorption of 170 to 300 cm3/100 g, a specific surface area as measured by a BET method of 250 to 400 m2/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 cm3/g. The electrocatalyst can be used in electrochemical devices such as solid polymer electrolyte fuel cells.

Abstract: A carbon black is provided which is useful as an electrocatalyst carrier. The carbon black has a DBP oil absorption of 170 to 300 cm3/100 g, a specific surface area as measured by a BET method of 250 to 400 m2/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 cm3/g. The electrocatalyst can be used in electrochemical devices such as solid polymer electrolyte fuel cells.

Abstract: A process for producing carbon black by utilizing a reactor comprising a first gradually constricted reaction zone in which a mixture of a fuel and an oxygen-containing gas, is burned, a second gradually constricted reaction zone having a throat in which the resulting high temperature combustion gas is mixed and reacted with a hydrocarbon feedstock, and a third reaction zone provided with a quenching water spray for terminating the reaction, which comprises directing the high temperature combustion gas formed in the first reaction zone to form an axial stream flowing in substantially the same direction as the axial direction of the reactor, introducing the divided axial streams into the second reaction zone, and, in the second reaction zone, introducing the hydrocarbon feedstock from nozzles in a direction traversing the axial streams of the high temperature combustion gas.

Abstract: A process for producing carbon black by thermally decomposing a hydrocarbon starting material in a production furnace by introducing the starting material to a high temperature zone heated by a high temperature combustion gas formed by burning a fuel and an oxygen-containing gas by a high temperature combustion gas-generating burner, characterized in that an alkali metal compound and/or alkaline earth metal compound is (A) introduced from alkali burner, burner specially itemed for ionizing the alkali metal compound and/or alkaline earth metal compound, set independently from said high temperature combustion gas-generating burner, for burning a mixture of a fuel and an oxygen-containing gas, or (B) ionized in an ionizing furnace specially itemed for ionizing the alkali metal compound and/or alkaline earth metal compound, and then introduced to the production furnace.

Abstract: High-quality coloring carbon black having a specific surface area (S.sub.BET), an area average diameter (D.sub.a) and a pore volume (AV.sub.Hg) which make both the roughness factor (RF) and aggregate factor (AF) as calculated by the following equations, negative values:RF=S.sub.BET -28710/(D.sub.a)+1450AF=AV.sub.Hg +14.times.(D.sub.a)-290where S.sub.BET is the specific surface area (m.sup.2 /g) of the carbon black as measured by a BET nitrogen absorption method, D.sub.a is the area average diameter (m.mu.m) of the carbon black as measured by an electron microscopic measuring method, and AV.sub.Hg is the pore volume (cc/100 g) of the carbon black as measured by a mercury porosimeter, provided D.sub.a is at most 17 m.mu.m.

Abstract: A process for purifying carbon black which contains solid impurities by removing the solid impurities thererom, which process comprises suspending said carbon black uniformly in water to obtain a carbon black aqueous slurry and subjecting the slurry to sieving treatment by an ultrasonic vibration sieving apparatus.