Abstract: The present invention relates to a method of preparing chlorine dioxide (ClO2) from hydrochloric acid (HCl) and sodium chlorite (NaClO2) in the presence of water (H2O). The invention has for its object to further develop the method such that it is more economical to install and operate. The object is achieved when the hydrochloric acid is used in aqueous solution at a concentration of 27 to 33 wt %, the sodium chlorite is used in aqueous solution at a concentration of 22 to 27 wt % and the molar ratio of hydrochloric acid used to sodium chlorite used is between 2.14 and 4.2.

Abstract: The present invention relates to a method of preparing chlorine dioxide (ClO2) from hydrochloric acid (HCl) and sodium chlorite (NaClO2) in the presence of water (H2O). The invention has for its object to further develop the method such that it is more economical to install and operate. The object is achieved when the hydrochloric acid is used in aqueous solution at a concentration of 27 to 33 wt %, the sodium chlorite is used in aqueous solution at a concentration of 22 to 27 wt % and the molar ratio of hydrochloric acid used to sodium chlorite used is between 2.14 and 4.2.

Abstract: The present invention claims a process and an apparatus for the work-up by distillation of cleavage product mixtures produced in the cleavage of alkylaryl hydroperoxides. Usually, in the work-up by distillation of cleavage product mixtures which are produced in the cleavage of alkylaryl hydroperoxides, the cleavage product mixture is divided into three main fractions, for which at least two distillation columns are used. The use of two distillation columns has the disadvantage that the capital costs, and also the energy costs, in these conventional processes are relatively high. By means of the inventive process for the work-up by distillation of cleavage product mixtures, the equipment requirements and the energy consumption can be markedly reduced in comparison with customary plants, since the cleavage product mixture can be resolved into the three main fractions in only one apparatus.

Abstract: Phenol is separated from a mixture containing hydroxyacetone, cumene, water and phenol, by fractionating the mixture in a process with a fractional distillation step and a phase separation step to provide a single phenol fraction containing less than 300 ppm of hydroxyacetone. In the work-up by distillation of cleavage product mixtures, the hydroxyacetone can be removed from the cleavage product mixture together with a phenol fraction from which the hydroxyacetone has to be removed. A process can be used for purifying cleavage product mixtures obtained in the cleavage of alkylaryl hydroperoxides such as cumene hydroperoxide. The process allows separation of phenol and acetone from mixtures obtained in the cleavage of cumene hydroperoxide.

Abstract: Aminoalkylsilanes of formula I: R1R2N—(CH2)y—Si(OR3)3−nR4n  (I), wherein R1 and R2 are each independently, identical of different, hydrogen, aryl, arylalkyl or C1-4-alkyl; R3 and R4 are each independently, identical or different, C1-8-alkyl or aryl; y is 2, 3 or 4 and n is 0 or 1, 2 or 3, are prepared by a process comprising: reacting an organosilane of formula II: X—(CH2)y—Si(OR3)3−nR4n  (II), wherein X is Cl, Br, I or F; and R3, R4, y and n are each as defined above with ammonia or an organic amine compound of the formula: HNR1R2  (III),  wherein R1 and R2 are each as defined above with at least one of R1 and R2 not being hydrogen in a liquid phase; evaporating ammonia or organic amine under reduced pressure while ammonium chloride or aminohydrochloride by-products, produced in the reaction of the first step, remains dissolved in the liquid phase; transferring the product mixture after said evaporation to another vessel operate

Abstract: Phenol is separated from a mixture containing hydroxyacetone, cumene, water and phenol, by fractionating the mixture in a process with a fractional distillation step and a phase separation step to provide a single phenol fraction containing less than 300 ppm of hydroxyacetone. In the work-up by distillation of cleavage product mixtures, the hydroxyacetone can be removed from the cleavage product mixture together with a phenol fraction from which the hydroxyacetone has to be removed. A process can be used for purifying cleavage product mixtures obtained in the cleavage of alkylaryl hydroperoxides such as cumene hydroperoxide. The process allows separation of phenol and acetone from mixtures obtained in the cleavage of cumene hydroperoxide.

Abstract: The present invention claims a process and an apparatus for the work-up by distillation of cleavage product mixtures produced in the cleavage of alkylaryl hydroperoxides. Usually, in the work-up by distillation of cleavage product mixtures which are produced in the cleavage of alkylaryl hydroperoxides, the cleavage product mixture is divided into three main fractions, for which at least two distillation columns are used. The use of two distillation columns has the disadvantage that the capital costs, and also the energy costs, in these conventional processes are relatively high.

Abstract: Aminoalkylsilanes of formula I:

Abstract: A process for the continuous preparation of 3-halopropylorganosilanes of the general structure RbH3-a-bXaSiCH2CH2CH2Y  (III), where: R is CH3, C2H5, C3H7, OCH3, OC2H5 or OC3H7, X is F, Cl, Br or I, Y is F, Cl, Br or I, and a and b are each one of the numbers 0, 1, 2 or 3 and the sum a+b is 1, 2 or 3, comprising reacting, as starting materials, an allyl halide with a silane carrying at least one H atom, wherein the starting materials are present in stoichiometric amounts or one of the starting materials is present in substoichiometric amounts, wherein the reaction carried out is a partial reaction of from 10% to 80%, on a molar basis, of the starting materials, based on either material, when both are present in stoichiometric amounts, or based on the substoichiometric material.

Abstract: A process is disclosed for the purification of an off-gas which originates from the oxidation of xylene with air in the Witten process for the preparation of dimethyl terephthalate by subjecting the off-gas to a partial condensation step to remove constituents such as dimethyl terephthalate and xylene; then contacting the off-gas with a solvent such as para-toluic acid or a mixture of para-toluic acid and methyl benzoate so as to remove contaminants such as para-xylene out of the off-gas; then contacting the off-gas with a solvent such as methyl benzoate to remove contaminants such as methyl para-toluate out of the off-gas; then contacting the off-gas with water so as to remove contaminants such as methanol out of the off-gas, and then combusting the off-gas.

Abstract: A process is provided for the oxidation of p-xylene and methyl p-tolulate with oxygen-containing gases in the Witten-Hercules process for preparing dimetyl terephthalate in at least two sequentially arranged stages and in the presence of a catalyst, wherein the process involves oxidizing p-xylene and methyl p-toluate with oxygen containing gases in at least two sequential stages in the presence of a catalyst, wherein the at least two sequential stages include at least one p-xylene rich stage and at least one methyl p-toluate rich stage, wherein at least one of the following steps (a) and (b) occurs:(a) in the at least one p-xylene rich stage at least a portion of p-xylene present is oxidized in the presence of 5 to 30% by mass of methyl p-toluate, based on a total amount of oxidation mixture in the at least one p-xylene rich stage; or(b) in the methyl p-toluate rich stage at least one of methyl p-toluate or p-toluic acid is oxidized in the presence of 2 to 30% by mass of p-xylene, based on a total amount of m

Abstract: A process for the preparation of terephthalic acid (TA) from pure dimethyl terephthalate (DMT) and/or DMT intermediate product by hydrolysis in a countercurrent reactor at a conversion of greater than 99% and crystallization to give the solid product, characterized in that the sum of the stripping steam (S) and reaction water (W) satisfies the relationshipL.ltoreq.S+W.ltoreq.2L,wherein (L) represents the amount of water necessary to keep the terephthalic acid (TA) produced largely in solution during the reaction and in the bottom of the reactor, and the terephthalic acid produced is crystallized in a crystallization which is free from washing stages.

Abstract: In the purification of an off-gas stream originating from a process of oxidizing a liquid mixture of para-xylene with methyl para-toluate with an oxygen-containing gas under pressure, the off-gas being contaminated with at least one of an aliphatic and an aromatic impurity, which comprises expanding the off-gas stream in an expansion turbine for generating mechanical or electrical energy so as to obtain an at least partial recovery of the energy contained in the off-gas, the improvement comprising subjecting the off-gas to at least one absorption step under pressure to remove at least one component from the off-gas and subjecting the resultant off-gas stream to combustion under a pressure of more than 3 bar prior to expanding the off-gas stream in the expansion turbine.

Abstract: The invention relates to a process for the production of a DMT intermediate product as well as its working up to fibregrade DMT and to medium pure and pure terephthalic acid.

Abstract: The invention relates to a process for the production of a DMT intermediate product as well as its working up to fibregrade DMT and to medium pure and pure terephthalic acid.

Abstract: A reactor for carrying out heterogeneous-phase reactions, in particular gas/liquid reactions with a continuous liquid phase and a dispersed (discontinuous) gas phase, is described, in which, in a horizontal plane, a substantially vertically upward-directed flow of the reaction medium takes place in a first region of the reactor cross-section and a substantially vertically downward-directed flow takes place in another region of the reactor having a device for dispersing the discontinuous phase such as a dispersing screen, substantially only in the regions with upward-directed flow. The reactor is here designed in such a way that free flow of the reaction medium from regions with downward-directed flow to regions with upward-directed flow is possible in the region of the dispersing device. The preferred use of the proposed reactor is the exothermic oxidation of p-xylene and monomethyl p-toluate with air in the so-called Witten DMT process.