Abstract: The present invention concerns a particulate agent for chemical and/or physical treatment of a fluid, such as a gas containing NO.sub.x and SO.sub.x, contains at least two particle types of different activity, the particle weight and/or particle size of each type lying within separate ranges. The agent may also contain catalyst particles for reducing NO.sub.x, and particles for absorbing SO.sub.x.The invention also concerns a method and a plant for treating a fluid with the inventive particulate agent.

Abstract: The invention relates to a catalyst for the reduction of nitrogen oxides and comprises oxides of transition metals on a particulate carrier material, the catalyst comprising:1) a carrier material consisting of small grains of an inorganic oxide,2) a catalytic layer thereon containing TiO.sub.2 and V.sub.2 O.sub.5, and obtained by a separate or simultaneous coating of the components on the carrier material,the catalyst particles being in the order of 10-200 .mu.m and the catalyst being intended to operate at temperatures of 150.degree.-220.degree. C.The invention also relates to a method for the preparation of the catalyst, and the use thereof for the reduction of nitrogen oxides in gases at low temperatures.

Abstract: A cracking catalyst having good resistance to metal poisoning has at least two particle fractions of different particle sizes, the cracking catalyzing zeolite material being concentrated to the coarser particle size fractions, and the finer particle size fractions being formed from material having relatively lower or no or insignificant cracking catalyzing activity. The particles of the finer particle size fractions have a matrix of kaolin and amorphous alumina-silica and may contain for example, an SO.sub.x eliminating additive such as Al.sub.2 O.sub.3, CaO and/or MgO. The coarser particle size fractions having cracking catalyzing effect have a mean particle size of from 80 to 125 .mu.m and the finer particle size fractions a mean particle size of from 30 to 75 .mu.m.