(174a) Catalytic Ozone Oxidation Processes for Waste Gases Treatment From Kraft Pulping Mills

Pulp and paper industry consumes vast quantities water and energy resources and generates large amounts of pollutants including an average of 4.5x105 lb toxic substances per facility released to air, water, and land. The combined air and water "cluster rule," which was part of the Pollution Prevention Acts of 1990, has set goals for reduction in annual emissions of hazardous air pollutants (HAPs), volatile organic compounds (VOCs) and total reduced sulfur compounds (TRSs) of the various sources of the industry. As the pulp and paper industry is moving to a cleaner and sustainable future, emerging technologies can have major impacts in reducing wastes generation in a cost effective way.

The typical pollutants from Kraft pulp mill are H2S, CH3SH, CH3SCH3, CH3SSCH3 and methanol. We have conducted bench and pilot scale studies to develop, demonstrate and evaluate the performance and the feasibility of utilizing catalytic oxidation of these are air pollutants that are found at high concentrations. Ozone is used as an oxidant and Cu, Mo and Mn oxides, and mixed oxide catalysts supported on ?×-alumina at temperatures ranges 100-200¢XC. Maximum conversion of DMS was obtained using 10-wt% MnO2/?×-Al2O3 as a catalyst, however, the selectivity towards partial oxidation products such as dimethyl sulfoxide and dimethyl sulfone are high (?l20%). The best catalytic activity is obtained over 10-wt% CuO-10- wt% MoO3/?×-alumina catalyst with 100 % DMS conversion, high selectivity (?l96%) towards complete oxidation products such as CO2 and SO2. Although, MoO3/?×- Al2O3 catalyst shows poor catalytic activity, MoO3 acts as a good promoter when used with CuO.

The catalyst was not poisoned by the sulfur compounds and remained active even at high concentrations of water (~50%). Catalytic oxidation occurs at lower temperatures and has key environmental advantages over incineration, including the minimal formation of nitrogen oxides (NOx) and lower energy requirements. The process converts methanol, a highly flammable toxin produced by the pulping of wood, into methyl formate and completely removes odor causing TRSs. We have achieved 98+ % removal of individual hazardous air pollutants, and total reduced sulfur (TRS) compounds. The new technology was tested using a pilot-scale unit at a commercial pulp and paper mill, Domtar Corporation pulp mill in Hawseville, Kentucky.