Catalytic process for removing toxic gases from gas streams

• Main Authors: GAUDET; GARY G, PALILLA; FRANK C, BAGLIO; JOSEPH A
• Format: Patent
• Language: English
• Published: 22.02.1983
• Subjects: CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOIDCHEMISTRY; CHEMISTRY; COMPOUNDS THEREOF; INORGANIC CHEMISTRY; METALLURGY; NON-METALLIC ELEMENTS; PERFORMING OPERATIONS; PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL; SEPARATION; THEIR RELEVANT APPARATUS; TRANSPORTING

A multi-stage process for reducing the content of sulfur-containing gases-notably hydrogen sulfide, sulfur dioxide, carbonyl sulfide and carbon disulfide-in waste gas streams is provided. In the first stage, the gas stream is passed through a reaction zone at a temperature between about 150 DEG and 350 DEG C. in the presence of a pretreated novel catalyst of the formula xLn2O3.yT2O3 in which Ln is yttrium or a rare earth element and T is cobalt, iron or nickel, and each of x and y is independently a number from 0 to 3, said catalyst being substantially non-crystalline and having a surface area of from about 10 m2/g to about 40 m2/g. The preferred catalyst is one in which Ln is lanthanum, T is cobalt, and x and y range from 1 to 3, including non-integers. The first stage yields a product stream having a reduced content of sulfur-containing gases, including specifically, substantial reduction of carbonyl sulfide and virtual elimination of carbon disulfide. An intermediate stage is a Claus reaction, which may take place in one or more reaction zones, at temperatures less than about 130 DEG C., in the presence of known catalysts such as bauxite, alumina or cobalt molybdates. The final stage is the air oxidation of hydrogen sulfide at a temperature between about 150 DEG and 300 DEG C. in the presence of a catalyst usable in the first stage.