Abstract:
The present invention relates to a reactor for the photocatalytic treatment of liquid or gas currents, comprising a pipe which the current to be treated flows through. At least one light source, at least one planar means M1 and at least one planar means M2 are arranged inside said pipe, wherein M1 has at least one photocatalytically active material and M2 reflects the light radiation emitted from the at least one light source. The reflective surface of the at least one means M2 and the inner wall of the pipe together form an angle that is greater than or equal to 0°, such that the light emitted from the light source is reflected from the at least one means M2 onto the photocatalytically active material. The invention further relates to a method for the photocatalytic treatment of liquid or gas currents by irradiation of light in the reactor according to the invention.
Abstract:
A plant for removing isobutene from an isobutene-containing C4-hydrocarbon mixture comprises an etherification unit containing moist acidic ion exchange resin, a first distillation unit, an ether cleavage unit, and a second distillation unit. A process for starting up the plant comprises: (a) filling the etherification unit with isobutanol; (b) filling the first distillation unit with C4-hydrocarbon and/or isobutanol, and operating the first distillation unit with total reflux; (c) filling the second distillation unit with C4-hydrocarbon and/or isobutanol, and operating the second distillation unit with total reflux; (d) withdrawing a bottom product of the second distillation unit, removing water from the bottom product and directing the bottom product to the etherification unit; (e) directing a discharge of the etherification unit to the first distillation unit; (f) directing a bottom product of the first distillation unit to the second distillation unit while bypassing the ether cleavage unit; (g) after the bottom product of the second distillation unit is essentially free of water, providing a flow of isobutene-containing C4-hydrocarbon mixture into the etherification unit and reacting the isobutene-containing C4-hydrocarbon mixture with isobutanol to form a mixture of IBTBE and unconverted hydrocarbons; (h) directing the mixture of IBTBE, unconverted hydrocarbons and unreacted isobutanol from the etherification unit to the first distillation unit and distilling the mixture to obtain a top product comprising the unconverted hydrocarbons, and a bottom product comprising IBTBE and unreacted isobutanol; (i) after IBTBE in the bottom product of the first distillation unit has reached a predetermined concentration, directing the bottom product of the first distillation unit to the ether cleavage unit to decompose the IBTBE to obtain isobutene and isobutanol; (i) directing the mixture of isobutene and isobutanol produced in step (j) to the second distillation unit and distilling the mixture of isobutene and isobutanol to obtain a top product comprising isobutene, and a bottom product comprising isobutanol and; (k) recycling the bottom product obtained in step (j) at least partially to the etherification unit. The stationary operation of the plant comprises (a) reacting an isobutene-containing C4-hydrocarbon mixture with isobutanol in the presence of an acidic ion exchange resin in an etherification unit to form a mixture of IBTBE and unconverted hydrocarbons; (b) distilling the reaction mixture in a first distillation unit to obtain a top product comprising the unconverted hydrocarbons, and a bottom product comprising IBTBE; (c) feeding the bottom product to a ether cleavage unit to decompose the IBTBE to obtain isobutene and isobutanol; (d) distilling the mixture of isobutene and isobutanol produced in step (c) in a second distillation unit to obtain a top product comprising isobutene, and a bottom product comprising isobutanol; and (e) recycling the bottom product of step (d) to step (a). A shutting down process comprises aa) taking the ether cleavage unit out of service and purging the ether cleavage unit with an inert gas; while the etherification unit, the first distillation unit and the second distillation unit stay in operation; bb) stopping the flow of isobutene-containing C4-hydrocarbon mixture into the etherification unit; cc) taking the etherification unit out of service; dd) operating the first distillation unit and the second distillation unit in total reflux mode; and ee) stopping the first distillation unit and the second distillation unit.
Abstract:
The invention relates to a method for producing reactive zinc by means of electrochemical reduction, wherein iron or steel is used as the cathode material.
Abstract:
The invention relates to a process for obtaining isobutene from an isobutene containing C4-hydrocarbon mixture (1) in a plant comprising an etherification unit (3), a first distillation unit (5), an ether cleavage unit (8) and a second distillation unit (10), the process comprising: (a) contacting the C4-hydrocarbon mixture (1) with a primary alcohol (2) and reacting the mixture with the primary alcohol in the presence of an acidic catalyst to form the corresponding alkyl tert-butyl ether as an intermediate product and diisobutene as a byproduct in the etherification unit (3); (b) distilling the reaction mixture (4) from the etherification unit (3) in the first distillation unit (5), a C4-hydrocarbon raffinate being withdrawn as the overhead product (6), the alkyl tert-butyl ether and diisobutene being withdrawn as the liquid or vaporous bottom product (7), and vaporizing the bottom product (7) if it is withdrawn as a liquid; (c) reacting the vaporous bottom product (7) in the presence of an acidic catalyst obtaining isobutene and the primary alcohol as reaction products in the ether cleavage unit (8); (d) distilling the reaction mixture (9) from the ether cleavage unit (8) in the second distillation unit (10), isobutene being withdrawn as the overhead product (11), the primary alcohol and diisobutene being withdrawn as the bottom product (12) and being recycled to the etherification unit (3); the plant further comprising a byproduct separation unit (15) being fed by a bottom purge stream (13) of the first distillation unit (5) and/or by a part of the bottom product of the second distillation unit (10), wherein a diisobutene product stream rich in diisobutene is separated from this feed stream (13, 14).
Abstract:
The invention relates to a process for preparing aromatic amines by hydrogenating corresponding nitroaromatics with hydrogen, and also to apparatus suitable for this purpose. The invention relates more particularly to a process for preparing tolylenediamine (TDA) by hydrogenation of dinitrotoluene (DNT).