Abstract: Sodium percarbonate is traditionally made in a crystallization process from aqueous hydrogen peroxide and sodium carbonate with recycle of mother liquor in the presence of a substantial concentration of a salting out agent, conventionally sodium chloride. The invention provides a process intended to be conducted without addition of chloride salting-out agent in which the dissolution step is controlled to restrict the sodium carbonate concentration to below 95%, preferably 60 to 90% of its saturated concentration at a temperature preferably controlled to at most 35C. and the mole ratio of hydrogen peroxide:sodium carbonate in the reaction vessel is controlled to between 0.7 to 1.2:1, and preferably about 1:1.

Abstract: The present invention relates to an apparatus for the continuous manufacture of solid particles of alkali metal persalts by reaction of an aqueous hydrogen peroxide solution with an aqueous solution of an alkali metal salt and crystallization of the persalt. The persalt is formed in a crystallizer classifier, which is made up of stirred region and a growth region for the persalt crystals a non-stirred clarifying region for the solution and a classification region for the particles obtained by elutriation in a liquid stream withdrawn in the clarifying region.

Abstract: Process for bleaching a chemical paper pulp to a brightness of at least 89° ISO, consisting in subjecting the pulp to a treatment sequence of several stages including a final bleaching stage with hydrogen peroxide in alkaline medium carried out in the presence of at least one stabilising agent and at a consistency of at least 25% by weight of solids, the stages preceding this final stage having purified the pulp so that its manganese content does not exceed 3 ppm by weight with respect to the solids and that the pulp has been delignified beforehand to a kappa number not exceeding 5.

Abstract: Continuous process for the manufacture of solid particles of alkali metal persalts by reaction of an aqueous hydrogen peroxide solution with an aqueous solution of an alkali metal salt and crystallization of the persalt formed in a crystallizer-classifier comprising a stirred formation and growth region for the persalt crystals, a nonstirred clarifying region for the solution and a classification region for the particles obtained by elutriation in a liquid stream withdrawn in the clarifying region.Plant for manufacturing the said particles.

Abstract: A process is proposed for the chemical oxidative treatment of a medium, e.g. sewage sludge, containing organic constituents, which comprises two process steps. In the first process step, the medium is heated to a first preset low temperature range and kept in this temperature range for a preset treatment duration. In a second process step, the sludge is then heated to a second preset low temperature range, pressurized in a preset low pressure range and kept in this temperature and pressure range for a preset treatment duration. In the course of this, an oxygen-containing gas, e.g. air or oxygen-enriched air or technical grade oxygen is introduced into the medium at least intermittently. The low temperatures and pressures provided in the two process steps are below or at most in the lower third of the temperature and pressure ranges of 150.degree.-370.degree. C. and 10-220 bar conventional in the wet-oxidation processes.

Abstract: A process for bleaching a chemical paper pulp, including, in the order recited, subjecting the chemical paper pulp to treatment with oxygen in a preliminary delignification stage which does not employ chlorine in an acidic medium or a combination of chlorine and chlorine dioxide in an acidic medium; subjecting the chemical paper pulp to treatment with peroxymonosulphuric acid in a peroxymonosulphuric acid stage carried out at a temperature ranging between 75.degree. and 100.degree. C. for a period ranging between 70 and 150 minutes and at a pulp consistency of ranging between 12 and 25% of dry matter; and subjecting the chemical paper pulp to treatment with alkaline hydrogen peroxide in an alkaline hydrogen peroxide stage.

Abstract: Continuous process for the manufacture of solid alkali metal persalt particles coated by crystallization of a supersaturated aqueous solution of persalts and covering of the persalt particles in a post-crystallization vessel into which at least one coating agent is introduced and in which crystallization of the coating agent around the persalt particles is carried out under controlled temperature and stirring conditions.

Abstract: Process for bleaching a chemical paper pulp by means of a sequence of treatment stages involving at least one stage with an enzyme and at least one stage with a peroxyacid.

Abstract: Process for improving the selectivity of the delignification of a chemical paper pulp by employing a peroxyacid, in which the unbleached pulp originating from the cooking operation is treated with an aqueous solution of this organic peroxyacid in the presence of at least one stabilizer selected from phosphonic acids and their salts.

Abstract: Process for the synthesis of alkylated aromatic hydrocarbons containing a saturated alkyl chain comprising at least four carbon atoms, according to which an aromatic hydrocarbon substituted by a saturated short-chain alkyl group comprising one to three carbon atoms is reacted with an olefin in the presence of a catalyst which comprises at least one alkali metal or one alkali metal hydride impregnated on an alumina support and the catalyst is prepared in the reaction medium in the presence of the aromatic hydrocarbon containing a short alkyl chain by mixing anhydrous alumina with the alkali metal hydride or with the alkali metal, the ratio by weight of the alkali metal or of the alkali metal hydride to the alumina support being between 0.6 and 1.8. Use of the process for the synthesis of tert-amylbenzene by alkylation of cumene with ethylene.