Catalytic vent gas treatment system for abatement of volatile chemical emissions

A process for abatement of volatile chemical emissions from an industrial unit which forms an aromatic acid from a corresponding methyl substituted aromatic compound by catalytic liquid-phase oxidation of the methyl groups with excess dioxygen in the presence of a source of bromine, the process comprising:

• (A-9) Dispersing a combustible fluid comprising at least one member of the group consisting of carbon monoxide, hydrogen, methanol, ethanol, 1-propanol, 2-propanol, 2-butanol and 2-methyl-2-propanol, into a vent gas stream containing dioxygen, carbon monoxide, hydrocarbons and other organic compounds comprising one or more alkyl bromide compound of 1 to 5 carbon atoms, at pressures in a range from atmospheric to about 300 psig;
• (B-9) Oxidizing the combustible fluid and destroying at least 90 percent of the carbon monoxide, at least 80 percent of the hydrocarbons, and at least 50 percent of the alkyl bromides in the vent gas stream in the presence of a solid oxidation catalyst which comprises at least one member of the group consisting of silica, alpha alumina, titania, silica alumina, zirconia and gamma alumina, and optionally at least one member of the group consisting of tungsten oxide, vanadium oxide, tin oxide, and the metals platinum, palladium and rhodium,
• (C-9) Controlling the amount of combustible fluid being delivered to the vent gas stream so as to provide sufficient reactants for catalytic oxidation to maintain suitable reaction temperatures in the range from 200° C. to 600° C. for the catalytic oxidation to form an oxidation effluent stream comprising unreacted dioxygen, carbon dioxide, water, hydrogen bromide and/or bromine;
• (D-9) Cooling the oxidation effluent stream from the catalytic oxidation by passing, simultaneously, the oxidation effluent stream and untreated vent gas stream through a gas to gas exchanger to transfer heat therebetween;
• and
• (E-9) Contacting the cooled oxidation effluent gas stream with an aqueous medium comprising at least one member of the group consisting of lime, ammonia, sodium formate, sodium oxalate, sodium sulfide, urea and formaldehyde in a gas scrubbing tower to form a liquid solution of soluble compounds and a treated vent gas stream.

A process for abatement of volatile chemical emissions from an industrial unit which forms an aromatic acid from a corresponding methyl substituted aromatic compound by catalytic liquid-phase oxidation of the methyl groups with excess dioxygen in the presence of a source of bromine, the process comprising:

• (A-17) Dispersing a combustible fluid selected from the group consisting of carbon monoxide, hydrogen, methanol, butane and mixtures thereof, into a vent gas stream containing dioxygen, carbon monoxide, hydrocarbons and other organic compounds comprising methyl bromide, at pressures in a range from about 10 to about 300 psig;
• (B-17) Oxidizing the combustible fluid and destroying at least 95 percent or more of the carbon monoxide, 90 percent or more of the hydrocarbons, and 85 percent or more of the methyl bromide in the vent gas stream in the presence of a solid oxidation catalyst which comprises titania and at least one member of the group consisting of tungsten oxide, vanadium oxide, tin oxide, and the metals platinum, palladium and rhodium,
• (C-17) Controlling the amount of combustible fluid being delivered to the vent gas stream so as to provide sufficient reactants for catalytic oxidation to maintain suitable reaction temperatures in the range from 200° C. to 600° C. for the catalytic oxidation to form an oxidation effluent stream comprising unreacted dioxygen, carbon dioxide, water, hydrogen bromide and/or dibromine;
• (D-17) Cooling the oxidation effluent stream from the catalytic oxidation by passing, simultaneously, the oxidation effluent stream and untreated vent gas stream through a gas to gas exchanger to transfer heat therebetween;
• and
• (E-17) Contacting the cooled oxidation effluent gas stream with an aqueous medium comprising at least one member of the group consisting of sodium formate, sodium oxalate, sodium sulfide, urea and formaldehyde in a gas scrubbing tower to form a liquid solution of soluble compounds and a treated vent gas stream.