Two-section type switchable tubular reactor and method for preparing alcohol through aldehyde gas phase hydrogenation by using same

Abstract

The invention relates to a two-section type switchable tubular reactor and a method for preparing alcohol through aldehyde gas phase hydrogenation by using the same. The reactor comprises an I section reactor, an II section reactor, a valve and pipelines both capable of switching the feeding sequence of raw materials of the two section reactors, and a valve and pipelines both capable of controlling a reaction temperature of the two section reactors. By adopting the two-section switchable tubular reactor for the aldehyde gas phase hydrogenation, the activity of a catalyst in the reactor having the precedent feeding sequence is reduced, but the activity of the catalyst in the reactor having the later feeding sequence is reduced a little after the reaction lasts for a period of time. Through the valve control, the method for preparing alcohol through aldehyde gas phase hydrogenation by using the two-section type switchable tubular reactor has the advantages of realizing the switching of the feeding sequence of the two section reactors and the control of the reaction temperature, increasing the utilization rate of the catalyst, prolonging the service life of the catalyst, prolonging the operating time of a device, saving production cost and the like.

Description

technical field [0001] The invention relates to a two-stage switchable tube-and-tube reactor and a method for preparing alcohol by using it to carry out gas-phase hydrogenation of aldehydes. Background technique [0002] When C2-C8 aldehydes are gas-phase hydrogenated to prepare C2-C8 alcohols, a fixed-bed gas-phase hydrogenation reactor is used. Compared with a liquid-phase hydrogenation reactor, it has the characteristics of low operating energy consumption and long service life of the catalyst. [0003] EP0008767 discloses a process for preparing alcohols by gas-phase hydrogenation of C2-C8 aldehydes using reduced CuO / ZnO in a tubular reactor. When using propionaldehyde as a raw material, a product containing 99.81 wt% propanol can be obtained. [0004] DE4244273 discloses the use of reduced CuO-ZnO-Al in a tubular reactor 2 o 3 -Na 2 O is used as a catalyst to catalyze the hydrogenation of n-butyraldehyde, and a product containing 99.8 wt% of n-butanol can be obtaine...

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Problems solved by technology

[0009] (1) The single tube is long, the catalyst is easily crushed during loading, and the degree of tightness is difficult to control, resulting in uneven pressure difference of the tubes during actual operation, partial flow of gas phase raw materials, and a significant decrease in the service life of the catalyst

[0010] (2) The single tube is longer, the total pressure drop of the bed increases, and the power of the compressor used to circulate hydrogen increases, which easily causes the catalyst to be broken

[0011] (3) In the initial stage of catalyst use, the reaction is mainly concentrated on the lower catalyst. The intergranular growth of the catalyst due to high temperature, temperature difference and liquid immersion will cause the lower catalyst to break and stick. Participate in the reaction, the actual use efficiency of the catalyst decreases

It has been used to screen the unloaded catalyst, then add new catalyst and then put it back into the reactor for reduction, but during the unloading process, the catalyst loss is high, the operation is cumbersome, and the effect is not ideal

[0014] The heat of reaction in gas-phase hydrogenation of aldehydes is generated by soaking the heat exchange tubes in the shell-side condensate to generate low-pressure steam to remove the heat of reaction. If the catalyst bed is divided into two or more layers, the catalyst in the upper layer will participate in the reaction less and the reaction will be released. If there is less heat, the upper layer cannot maintain the corresponding temperature. Condensation of the reaction material will cause damage to the catalyst. To maintain this temperature, it is necessary to pass steam to the shell side, resulting in increased consumption.

[0015] To sum up, the existing one-stage single-pass tubular reactor catalyst has a short operating life. When the catalytic effect of the catalyst deteriorates, the conversion rate of aldehydes decreases, the selectivity of alcohols decreases, and the by-products increase, the device must be shut down and the catalyst must be screened. Or directly replace the catalyst, the operation is cumbersome, and the cost is increased, which is not conducive to long-term continuous industrial production

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