Abstract: A process for the production of 3-hydroxyalkanals, more particularly 3-hydroxypropionaldehyde, by hydration of the basic 2-alkenals, more particularly acrolein, in the presence of a solid catalyst containing acid functional groups. The catalysts are based on an inorganic support containing basic activity centers (which are at least partly occupied by a polybasic acid, of which the first pK.sub.s value is between 0 and 3, in a form in which it cannot be removed by water) enables the hydration to be carried out with high selectivity. At the same time, the disadvantages of known organic fixed-bed catalysts are avoided. Preferred catalyst are based on pyrogenic titanium dioxide with phosphoric acid fixed thereon.

Abstract: A catalyst for the selective reduction of nitrous oxide with ammonia contains, in addition to titanium oxide as component (A), at least one oxide of W, Si, B, Al, P, Zr, Ba, Y, La, Ce and at least one oxide of V, Nb, Mo, Fe, Cu as component (B), whereby the atomic ratio between the elements of components (A) and (B) amounts to 1:0.001 up to 1. The catalyst can be obtained by kneading reactive titanium oxide with a high specific surface of predominantly anatase with the substances of component (B) or their preliminary stages, adding processing agents, winding up with a homogeneous kneaded mass, extruding the latter, drying the extrudate and calcining in air at 300.degree.-800.degree. C.

Abstract: A device for the continuous measurement of the ammonia concentration in gases in the ppm range includes a columnar absorption vessel (1) with a hemispherical bottom (4). The bottom of the column includes an overflow (3) and an outlet (5). The gas introduction pipe (7,8) empties above the bottom (4) and below a sieve bottom (6) arranged in the column (1). A packing material (10) rests on the sieve bottom (6), which packing (10) essentially fills the absorption column (1). A cooling part (11) extends from the absorption column (1). The cooling part (11) includes a cooling zone (15) and a gas collection space (16) above it with a closable connection piece (13). A pipe (14), which may include a serrated crown on each end, runs from the gas collecting space (16) downward in a cooled manner to the packing 10. The liquid absorption agent is introduced through a lateral connection piece (18) into the gas collection space (16).

Abstract: Titanium dioxide compacts are produced by intensively mixing pyrogenically produced titanium dioxide in the presence of deionized water with a wetting agent and/or with a base and/or optionally with a binder and/or optionally with an auxiliary deformation agent and/or optionally with a pore former, extruding the mass thus obtained at pressures between 5 and 100 bars to form shaped articles, drying the shaped articles at temperatures between 50.degree. and 120.degree. C. and subsequently calcining the shaped articles in the ambient air at temperatures of 400.degree. to 700.degree. C. for 1 to 5 hours.

Abstract: A one-piece catalyst for purifying exhaust gases, particularly from internal combustion engines and gas turbines operated above the stoichiometric ratio. The one-piece honeycomb ceramic or metal carrier has a reduction catalyst on its leading-edge portion and an oxidation catalyst on its trailing-edge portion.

Abstract: A method for the removal of nitrogen oxides contained in exhaust gases of an optionally fluctuating composition with a temperature of 0.degree.-600.degree. C. by means of catalytic reduction at a preselected stoichiometric ratio between the concentration of reducing agent and the concentration of nitrogen oxide in which the reducing agent is dosed in a pulsed manner.

Abstract: A catalyst for the selective reduction with ammonia of nitrogen oxides from an intimate mixture of at least 3 metals in the form of their oxides, namely, titanium, tungsten and at least one of the metals vanadium, iron, niobium, molybdenum, with an atomic ratio of Ti to the other metals of 1:0.001 to 1, wherein there is used as oxide of the titanium a product obtained by flame hydrolysis, which product is impregnated with solutions of the salts of the other metals and is dried and calcined at a high temperature.

Abstract: A device for the support of ceramic catalyst monoliths especially of square cross section as well as for the combination of several of such monoliths into one package. It is formed of an elastic gasket attached on one or both monolith ends and a metal frame attached on the gasket under pressure. The frame has recesses on two adjacent lateral surfaces, and at the two opposite lateral surfaces it has projections which can engage interlockingly into the recesses of adjacent frames.

Abstract: A device for the containment of ceramic catalyst monoliths particularly of four cornered cross sectional area as well as for the combination of a plurality thereof into a package. The device includes elastic gaskets arranged on one of the ends of the monoliths and partitions for the form fitting containment of the elements into a cassette.

Abstract: A process is described for the purification of exhaust gases containing oxides of nitrogen and sulfur obtained from combustion installations and industrial production processes by selective catalytic reduction of the nitric oxides with ammonia, subsequent catalytic oxidation of sulfur dioxide with oxygen and conversion into sulfuric acid of the sulfur trioxide obtained.