Abstract: A catalytic reactor for reducing nitrogen oxide (NO.sub.x) contained in exhaust gas under the presence of ammonia is provided, wherein tubular catalyst units each being a ring shape in cross-section are disposed in spaced apart relationship from one another in the cross-section of the flow path of the exhaust gas in a manner that tubular axes thereof are in parallel with the direction of gas flow within a reaction vessel through which the exhaust gas containing nitrogen oxide (NO.sub.x) and ammonia flows, said catalyst units each being secured to the interior of the reaction vessel at least as two points in the longitudinal direction by support means.

Abstract: Improved process for producing terephthalic acid by liquid-phase catalytic oxidation of p-xylene with oxygen at a temperature of at least about 160.degree. C. and a pressure of at least about 5 kg/cm.sup.2 G under specific recycling condition of the mother liquor, which comprises(A) performing said liquid-phase catalytic oxidation at a temperature (T) within the range of about 170.degree. C. to about 230.degree. C. to form an oxidation reaction mixture containing crude terephthalic acid having a 4-carboxybenzaldehyde content of 500 to 3,000 ppm and an optical density, measured at 340 m.mu., of not more than 0.3,(B) separating about 60 to about 98% by weight of the total mother liquor from the resulting oxidation reaction mixture at a temperaure of from (T-30).degree. C. to (T+10).degree. C.

Abstract: A catalyst composition for the vapor phase reduction of nitrogen oxides with ammonia, which consists essentially of a non-noble transition metal compound supported on a shaped carrier comprising a titanium oxide and a clay mineral having an average particle size of 0.1 to 100 microns. The shaped carrier preferably contains an additional component which is an inorganic fibrous material, silica hydrogel, silica sol, or a mixture of at least two of these. An exhaust gas containing nitrogen oxides is treated, with a high percent NO removal, by contacting it with the catalyst composition in the presence of ammonia gas at 200.degree. to 600.degree. C.

Abstract: A catalyst composition for the vapor phase reduction of nitrogen oxides with ammonia, which consists essentially of a non-noble transition metal compound supported on a shaped carrier comprising a titanium oxide and a clay mineral having an average particle size of 0.1 to 100 microns. The shaped carrier preferably contains an additional component which is an inorganic fibrous material, silica hydrogel, silica sol, or a mixture of at least two of these. An exhaust gas containing nitrogen oxides is treated, with a high percent NO removal, by contacting it with the catalyst composition in the presence of ammonia gas at 200 to 600.degree. C.