Cabot patents multi-stage process for making carbon black

Patent No. U.S. 7,829,057 B2
Cabot Corp. has been granted a patent for a process of making a carbon black product comprised of in a multi-stage carbon black reactor having a converging diameter section, forming a stream of hot gases at a stage having a diameter and at a location upstream of where any of carbon black yielding feedstock is introduced into the multi-stage carbon black reactor, downstream of the converging diameter section, forming a precursor consisting essentially of a first carbon black in a first carbon black formation site in the multi-stage carbon black reactor comprised of introducing a first carbon black yielding feedstock and the hot gases into the first carbon black formation site, and downstream of where the first carbon black yielding feedstock is introduced, then introducing a second carbon black yielding feedstock to the precursor in a second carbon black formation site in the reactor and forming the carbon black product in the second carbon black formation site before a complete quench zone, and further is comprised of introducing at least one substance containing at least one Group IA or Group IIA element prior to and/or during introducing the second carbon black yielding feedstock, wherein the second carbon black formation site is located downstream from the first carbon black formation site in a direction of gas flow in the reactor, and wherein no oxidizing source and no fuel source for generating hot combustion gases is introduced after formation of the precursor, and wherein the first carbon black formation site and second carbon black formation site have a temperature difference (Δ) of 200° C or more as determined from respective first and second temperatures determined in the reactor where the first and second carbon black yielding feedstocks are respectively introduced in the reactor, and wherein the second carbon black yielding feedstock is at least 15% by weight of the total amount by weight of carbon black yielding feedstock, wherein the first carbon black yielding feedstock and second carbon black yielding feedstock are introduced at stages of the multi-stage carbon black reactor having diameters that are narrower than the diameter of the stage of where the stream of hot gases is formed; and the carbon black product consisting essentially of a carbon black having a DBP in a range of from approximately 30 to 150 cc/100 g and an STSA in a range of from 10 to 180 m2/g.