摘要:
An isocyanate is produced by:(a) reacting chlorine with carbon monoxide to form phosgene, (b) reacting the phosgene with an organic amine to form an isocyanate and hydrogen chloride, (c) separating the isocyanate and hydrogen chloride, (d) optionally, purifying the hydrogen chloride, (e) preparing an aqueous solution of the hydrogen chloride, (f) optionally, purifying the aqueous solution of hydrogen chloride, (g) subjecting the aqueous hydrogen chloride solution to electrochemical oxidation to form chlorine, and (h) returning at least a portion of the chlorine produced in (g) to (a).
摘要:
The invention describes an electrochemical cell for the electrolysis of an aqueous solution of hydrogen chloride, comprising at least an anode half-cell with an anode, a cathode half-cell with a gas diffusion electrode as cathode and an ion exchange membrane arranged between the anode half-cell and the cathode half-cell, the membrane consisting of at least a perfluorosulfonic acid polymer, wherein the gas diffusion electrode and the ion exchange membrane are adjacent to each other, characterised in that the gas diffusion electrode and the ion exchange membrane, under a pressure of 250 g/cm2 and at a temperature of 60° C., have a contact area of at least 50%, with respect to the geometric area.
摘要翻译:本发明描述了用于电解氯化氢水溶液的电化学电池,至少包括具有阳极的阳极半电池,具有气体扩散电极作为阴极的阴极半电池和布置在阳极之间的离子交换膜 半电池和阴极半电池,所述膜由至少全氟磺酸聚合物组成,其中所述气体扩散电极和所述离子交换膜彼此相邻,其特征在于,所述气体扩散电极和所述离子交换膜, 在250g / cm 2的压力和60℃的温度下,相对于几何面积具有至少50%的接触面积。
摘要:
The invention relates to a method for producing silane (SiH4) by a) reacting metallurgical silicon with silicon tetrachloride (SiCl4) and hydrogen (H2), to form a crude gas stream containing trichlorosilane (SiHCl3) and silicon tetrachloride (SiCl4), b) removing impurities from the resulting crude gas stream by washing with condensed chlorosilanes, c) condensing and subsequently, separating the purified crude gas stream by distillation, d) returning the partial stream consisting essentially of SiCl4 to the reaction of metallurgical silicon with SiCl4 and H2, e) disproportionating the partial stream containing SiHCl3, to form SiCl4 and SiH4 and f) returning the SiH4 formed by disproportionation to the reaction of metallurgical silicon with SiCl4 and H2, the crude gas stream containing trichlorosilane and silicon tetrachloride being liberated from solids as far as possible by gas filtration before being washed with the condensed chlorosilanes. The washing process with the condensed chlorosilanes is carried out at a pressure of 25 to 40 bar and at a temperature of at least 150° C. in a single-stage distillation column and is carried out in such a way that 0.1 to 3 wt. % of the crude gas stream containing trichlorosilane and silicon tetrachloride is recovered in the form of a condensed liquid phase consisting essentially of SiCl4, this liquid phase then being removed from the SiCl4 circuit and expanded to a pressure of 1 bar outside said SiCl4 circuit and cooled to a temperature of 10 to 40° C., whereby dissolved impurities separate out and are then removed by filtration.
摘要:
A method for controlling a valve including a spring, an actuator having an actuator force opposing the spring, and a pin actuatable by the actuator. To open the valve, in a first operating mode a current having a predefined curve is applied to the actuator, starting from a starting value of the current at which the pin is positioned to allow the valve to close, measured values of the current are determined chronologically sequentially, a reference value of the current takes on the current measured value of the current when the measured current deviates from the applied current by a predefined degree. In a second operating mode, a current having a predefined curve is applied to the actuator, starting with the starting value of the current to a final value of the current at which the pin is in a position that prevents the valve from closing.
摘要:
A process is described for the production of graphite electrodes coated predominantly with noble metal for electrolytic processes, especially for the electrolysis of hydrochloric acid, wherein the surface of a graphite electrode is coated with an aqueous solution of a noble metal compound and then tempered at 150 to 650° C. in the presence of reducing and/or extensively oxygen-free gases.
摘要:
An electronic plug-in module for accommodation in a module rack with a mounting rail, wherein the plug-in module includes a circuit board, a front plate and a mounting device, the mounting device comprises a bearing part, a tensioning part and a fixation element, the bearing part is fixed on front plate, and the tensioning part is connected frictionally to the fixation element and the bearing part in such a manner that a force, by means of which the plug-in module is held with its front plate in a defined position relative to the module rack, is exerted onto the plug-in module transversely to the insertion direction of the plug-in module.
摘要:
Process wherein the vanadium present in the chromium ore chromite is recovered as vanadium pentoxide during the course of the fusion of the chromium ore with alkali and its work-up to produce sodium chromate solution and sodium dichromate.
摘要:
To create an orthodontic device with a base having a base surface for fixing the device to a tooth, and a slot for receiving an archwire, which is defined by a bottom surface and two side surfaces arranged on either side of the bottom surface and aligned in substantially parallel spaced relation to each other, and which extends in a substantially straight line through the base in the longitudinal direction of the base on a side thereof facing away from the base surface, and with a cover element for at least partially covering the open side of the slot facing the bottom surface, which is convertible and is easier to handle during the conversion, and which offers the wearer an increased degree of security, it is proposed that the side surfaces of the slot have a positively locking guide, which is aligned substantially parallel in relation to the longitudinal direction of the slot, and in which the cover element is slidably and detachably held on the base.
摘要:
The invention relates to a process for the production of sodium dichromate and sodium dichromate solutions by oxidative roasting of chrome ores under alkaline conditions, leaching of the furnace clinker obtained with water or an aqueous chromate-containing solution, adjustment of the pH to from 7 to 9.5, removal of the insoluble constituents by filtration, a sodium monochromate solution being obtained, conversion of the monochromate ions of this solution into dichromate ions by acidification and crystallization of sodium dichromate by concentration of this solution, characterized in that the acidification is carried out with carbon dioxide under pressure with removal of sodium hydrogen carbonate, the remaining solution is then very largely freed from sodium monochromate by cooling to a temperature below 10.degree. C. and filtration, any monochromate ions still present in the remaining solution are converted into dichromate ions by addition of an acid and the sodium monochromate filtered off is added to the sodium monochromate solution before conversion with carbon dioxide into a sodium dichromate solution.
摘要:
A process for the production of chromic acid, comprisinga) dissolving ferrochrome in sulphuric acid, optionally with the addition of catholyte and/or anolyte overflow from the electrolysis,b) removing undissolved constituents by filtration,c) adding a reducing agent in a quantity more than equivalent to the quantity of iron(III) and chromium(IV) in the solution,d) precipitating chromium(III) hydroxide by raising the pH to about 4-6 by the addition of a base while maintaining the reducing conditions in the solution,e) separating the precipitated chromium hydroxide while maintaining the reducing conditions,f) working up the aqueous solution containing iron by oxidation; precipitating iron(III) hydroxide or iron(III) oxide and optionally isolating the sulphate in the solution as sodium sulphate, ammonium sulphate or calcium sulphate,g) dissolving the separated chromium hydroxide in chromic acid and optionally sulphuric acid where either a single solution in chromic acid is produced or two solutions are produced, one in chromic acid and another in sulphuric acid,h) separating the solution(s) from undissolved constituents andi) employing the chromium hydroxide solution in chromic acid as anolyte in the electrolytic production of chromic acid in an electrolytic cell divided by a membrane, and either using the same solution as catholyte in the electrolytic cell divided by a membrane or using the chromium hydroxide solution in sulphuric acid as catholyte in the electrolytic cell divided by a membrane, hydrogen and/or metallic chromium being deposited electrolytically at the cathode and/or chromium(II) ions being produced electrolytically.