Abstract: A carbon-based catalyst which has a carbon content of >65% by weight and a content of substantially insoluble oxides of the metals Co, Fe, Ni, Cr, V, Mo, W, Cu, Mn and Ti of, in all, 0.1% by weight and a nitrogen content of 0.2 to 5% by weight. These catalysts are produced by a process wherein an organic material comprising unsaturated carbon-carbon bonds is pyrolyzed in a first step via the liquid phase stage, the product formed is size-reduced after cooling, mixed with substantially insoluble metal oxides and/or compounds forming substantially insoluble metal oxides together with binders and, optionally, water and the resulting mixture subjected to forming and heat treatment. The catalysts are useful in various gas-solid reactions more especially for the reductive destruction of nitrogen oxides in smoke gases.

Abstract: On a single-screw or multi-screw extruder, the part of the barrel lying between a front plate (1) and end plate (2) bounding the processing unit is subdivided into barrel discs (5) of ceramic materials, which are arranged on at least one guide rail (7). The barrel discs (5) are held together by an anchor (9) fixed on the front plate (1) and end plate (2) and at the same time secured against twisting. In addition, the screw elements (3) within the processing unit between front plate (1) and end plate (2) are also made from the same or from another ceramic material.