The invention is a method and a sulfuric acid plant design for reduction of start-up SO.sub.2, SO.sub.3 and H.sub.2SO.sub.4 emissions in sulfuric acid production, in which SO2 is converted to SO.sub.3 in n successive catalyst beds, where n is an integer >1. The final catalytic beds are used as absorbents for SO.sub.2 to SO3 during the start-up procedure, and one or more of the m beds downstream the first bed are purged, either separately or simultaneously, with hot gas, where m is an integer >1 and m<n, during the previous shut-down. Also, one separate purge with hot gas is used on the final bed.

A process where a gas, containing SO.sub.2 and O.sub.2 is brought in contact with a mixture of from 95% vol. to 50% vol. of activated carbon catalyst and from 5% vol. to 50% vol. of an inert filler material, where the SO.sub.2 is converted to H.sub.2SO.sub.4 on the activated carbon catalyst and is then washed from the activated carbon catalyst to obtain a H.sub.2SO.sub.4 solution.

A process where a gas, containing SO.sub.2 and O.sub.2 is brought in contact with a mixture of from 95% vol. to 50% vol. of activated carbon catalyst and from 5% vol. to 50% vol. of an inert filler material, where the SO.sub.2 is converted to H.sub.2SO.sub.4 on the activated carbon catalyst and is then washed from the activated carbon catalyst to obtain a H.sub.2SO.sub.4 solution.

A process where a gas, containing SO.sub.2 and O.sub.2 is brought in contact with a mixture of from 95% vol. to 50% vol. of activated carbon catalyst and from 5% vol. to 50% vol. of an inert filler material, where the SO.sub.2 is converted to H.sub.2SO.sub.4 on the activated carbon catalyst and is then washed from the activated carbon catalyst to obtain a H.sub.2SO.sub.4 solution.

A process where a gas, containing SO.sub.2 and O.sub.2 is brought in contact with a mixture of from 95% vol. to 50% vol. of activated carbon catalyst and from 5% vol. to 50% vol. of an inert filler material, where the SO.sub.2 is converted to H.sub.2SO.sub.4 on the activated carbon catalyst and is then washed from the activated carbon catalyst to obtain a H.sub.2SO.sub.4 solution.

The invention is a method and a sulfuric acid plant design for reduction of start-up SO.sub.2, SO.sub.3 and H.sub.2SO.sub.4 emissions in sulfuric acid production, in which SO2 is converted to SO.sub.3 in n successive catalyst beds, where n is an integer >1. The final catalytic beds are used as absorbents for SO.sub.2 to SO3 during the start-up procedure, and one or more of the m beds downstream the first bed are purged, either separately or simultaneously, with hot gas, where m is an integer >1 and m<n, during the previous shut-down. Also, one separate purge with hot gas is used on the final bed.

The present invention relates to a method for the catalytic removal of sulfur dioxide from waste gases in two reactors, wherein the first reactor is charged with an activated carbon catalyst. The method comprises: a. provision of a waste gas with a water content of less than 1 g H.sub.2O/Nm.sup.3 and an SO.sub.2 content of at least 5 ppm, b. introduction of the waste gases into a first reactor, c. catalytic conversion of the SO.sub.2 into gaseous SO.sub.3 in the first reactor by the activated carbon catalyst, wherein catalytic conversion on the activated carbon catalyst proceeds at a temperature of below 100 C., d. introduction of the prepurified waste gases from the first reactor into a second reactor, e. conversion of the SO.sub.3 with water into H.sub.2SO.sub.4 in the second reactor.

The present invention relates to a method for the catalytic removal of sulfur dioxide from waste gases in two reactors, wherein the first reactor is charged with an activated carbon catalyst. The method comprises: a. provision of a waste gas with a water content of less than 1 g H.sub.2O/Nm.sup.3 and an SO.sub.2 content of at least 5 ppm, b. introduction of the waste gases into a first reactor, c. catalytic conversion of the SO.sub.2 into gaseous SO.sub.3 in the first reactor by the activated carbon catalyst, wherein catalytic conversion on the activated carbon catalyst proceeds at a temperature of below 100 C., d. introduction of the prepurified waste gases from the first reactor into a second reactor, e. conversion of the SO.sub.3 with water into H.sub.2SO.sub.4 in the second reactor.

Commercial production of sulfuric acid is almost entirely accomplished nowadays using the contact process. And the trend is to increase conversion efficiency and reduce emissions of unconverted sulfur dioxide. By using a special combination of contact catalyst beds, a single contact single absorption (SCSA) system can be engineered to achieve the conversion and emission capabilities of conventional double contact double absorption systems. Thus, the complexity and cost of incorporating a second absorption tower and associated heat exchanger in the system can be omitted. In the SCSA system, the initial catalyst bed or beds comprise vanadium oxide catalyst and the last catalyst bed or beds comprise platinum catalyst operating at a much lower temperature than the initial beds.

A process plant for production of sulfuric acid from a process gas comprising SO2, including a process gas inlet, a first SO2 converter having an inlet and an outlet, a first condenser having a gas inlet, a gas outlet and a liquid outlet, a gas mixing device having a first inlet, a second inlet and an outlet, a process gas heater having an inlet and an outlet, a second SO2 converter having an inlet and an outlet, a second condenser having a gas inlet, a gas outlet and a liquid outlet, one or more means for cooling and storage of sulfuric acid and a purified process gas outlet.