Process for washing cyclohexene hydration catalyst and regenerating filter assembly

Abstract

The invention discloses a cyclohexene hydration catalyst washing and filtering assembly regeneration process, which comprises the following steps: introducing a hydration catalyst subjected to oil removal and oxidation regeneration into a washing and filtering system, and filtering impurities by using a high-flux metal filter element assembly instead of a ceramic membrane filter element, so as to realize regeneration of the catalyst; meanwhile, filter assembly regeneration equipment is matched, so that long-period stable operation of the filter device is ensured. By adopting a metal filter element filtering and matched regeneration technology, the strength of the filter element is improved, the flux of the filter assembly is increased, the filtering and washing efficiency of a catalyst is improved, the regeneration effect of the filter assembly is improved, and the operation cycle and the service life of equipment are prolonged.

Description

Technical Field

[0001] The present invention relates to the fields of catalyst filtration, catalyst regeneration, and filter regeneration, and particularly to a regeneration process for a cyclohexene hydration catalyst washing and filtering assembly. By adopting the cross-flow filtration of a high-flux metal filter element and the filter element regeneration technology, the strength of the filter element is improved, the flux of the filter assembly is increased, the catalyst filtration and washing efficiency is improved, the regeneration effect of the filter assembly is improved, the stability of the production device is ensured, and the operation cycle and service life of the equipment are extended. Background Art

[0002] Cyclohexanol is an important organic chemical compound with the chemical formula C6H12O. The domestic production capacity is about 10 million tons. Its main use is to produce nylon 6 and nylon 66. In addition, cyclohexanol can also be used in the fields of disinfectants, spices, insecticides, fungicides, leather softeners, and wood preservatives.

[0003] Industrially, the method for producing cyclohexanol is mainly to partially hydrogenate benzene to produce cyclohexene, and then use a ZSM-5 catalyst to catalyze the hydration of cyclohexene to obtain cyclohexanol. This technology was developed by Asahi Kasei Corporation of Japan in the 1990s as an efficient production process. In this technology, a hydration catalyst regeneration technology is provided, and the regeneration of the hydration catalyst is realized by means of steam high-temperature treatment, hydrogen peroxide oxidation, and regeneration filtration and washing in sequence. Among them, the regeneration filtration and washing technology mainly uses the cross-flow filtration of a ceramic membrane to wash the regenerated catalyst slurry, remove the impurities containing organic acids generated during the catalyst regeneration process, and uses acid washing to regenerate the ceramic filter element. The existing cyclohexene hydration catalyst washing and filter assembly regeneration technologies in China all follow the above technology with little change.

[0004] During the use of the cyclohexene hydration catalyst washing process, the following problems have emerged: 1). The ceramic membrane filter element has a high breakage rate and a short service life during use. The replacement process of the filter element is complex and the workload is large, seriously affecting production; 2). The ceramic membrane filter element has a small flux, a large number of filter elements, and a large installation and maintenance difficulty; 3). The ceramic membrane filter element has a short service cycle, frequent chemical acid washing regeneration, a large labor intensity, a large amount of regeneration reagent used, a large amount of waste water, and a high regeneration cost; 4). The ceramic membrane filter element has a small channel, a large pressure drop of the fluid passing through the ceramic filter element, and a large energy loss; 5). The flux of the ceramic membrane filter assembly decays rapidly, the backwashing pressure is low, and the backwashing effect is not good; 6). During the acid washing regeneration of the ceramic membrane, the acidic regeneration liquid is easy to corrode the equipment, resulting in safety problems; The inventors' research found that the existing research on the regeneration technology of cyclohexene hydration catalysts mainly focuses on high-temperature treatment, oxidation, etc., with less research on the subsequent catalyst regeneration filtration and washing technology. Moreover, all optimizations and improvements are based on ceramic membrane filtration technology, and the application of metal filters is not mentioned. Summary of the Invention

[0005] The present invention provides a regeneration process for a cyclohexene hydration catalyst washing and filtration assembly. By adopting the cross-flow filtration of a high-flux metal filter and the regeneration technology of the filtration assembly, the strength of the filter is improved, the flux of the filtration assembly is increased, the catalyst filtration and washing efficiency is improved, the regeneration effect of the filtration assembly is improved, the stability of the production device is ensured, and the operation cycle and service life of the equipment are extended.

[0006] The specific implementation solution of the present invention is as follows: 1). It includes a washing tank, a pre-filter, a filtration assembly, a backflush tank, and a regeneration liquid tank; 2). After the catalyst slurry to be cleaned enters the washing tank in an intermittent manner, the slurry forms a slurry circulation among the washing tank, the pre-filter, and the filtration assembly. At the same time, high-purity water continuously enters the washing tank, and the catalyst washing and filtration liquid exits the system as cleaning waste liquid; Among them, the filtration assembly includes multiple groups of filtration devices connected in series and / or in parallel. Preferably, there are 6 filtration devices, with three in series and two in parallel. Only three in series are used at the same time, and the other three in series are for standby; Among them, a high-flux metal filter is provided in the filtration device, and the filtration method is cross-flow; Among them, the structure of the high-flux metal filter is a single-layer and / or multi-layer composite structure. Preferably, it is a two-layer or three-layer composite structure; Among them, the outer diameter of the metal filter is 8 - 36 mm, and the filter thickness is 1 - 3 mm. Preferably, the outer diameter is 12 - 19 mm, and the thickness is 1.5 - 2.5 mm; Among them, the filtration accuracy of the filter is 0.05 - 3.00 μm. Preferably, the accuracy is 0.1 - 1 μm; Among them, the transmembrane filtration pressure difference is 1 - 300 kPa. Preferably, the transmembrane filtration pressure difference is 5 - 180 kPa; Among them, the pre-filter is regularly backflushed, and the intercepted large-particle solids are discharged from the system; Among them, a metal filter is provided in the pre-filter, and the filtration method is dead-end filtration; Among them, the filtration accuracy of the metal filter in the pre-filter is 1 - 50 μm. Preferably, the filtration accuracy is 3 - 20 μm; 3). During the washing and filtration process of the hydration catalyst slurry, the filtration assembly is regularly backflushed online through the backflush tank; Among them, the backwashing method of the backwashing tank for the filter component is pressure-driven or pump-driven. Preferably, the backwashing method is pressure-driven; Among them, the object of single-time backwashing is one or more filters. Preferably, it is a single filter; Among them, the online backwashing pressure difference is 0.5 - 6.0 bar. Preferably, the backwashing pressure difference is 2.0 - 4.0 bar; Among them, the online backwashing time interval for a single filter is 5 - 240 min. Preferably, the time interval is 10 - 60 min; Among them, the single-time backwashing time is 0.5 - 30 s. Preferably, the time is 1 - 8 s; Among them, the backwashing liquid medium is high-purity water; Among them, the temperature of the backwashing medium is 50 - 90 °C. Preferably, the temperature is 65 - 85 °C; 4). The regeneration liquid tank is filled with regeneration agents, and the filter component is regenerated regularly. The regeneration of the filter component is achieved through the self-circulation of the regeneration liquid and the filtration cycle of the regeneration liquid. The regeneration waste liquid is discharged from the system regularly; Among them, the chemical regeneration method of the filter component is one or several of pickling regeneration, water washing regeneration, and alkali washing regeneration. Preferably, the regeneration method is the coupling of water washing regeneration and alkali washing regeneration; Among them, there is one or more regeneration liquid tanks. Preferably, it includes a water washing tank and an alkali washing tank; Among them, the concentration of the regeneration alkali liquid is 0.1 - 15 wt.%. Preferably, the concentration is 3 - 10 wt.%; Among them, the regeneration temperature is 5 - 90 °C. Preferably, the regeneration temperature is 40 - 80 °C; Among them, the operation cycle after regeneration is 1 - 120 days. Preferably, the operation cycle is 5 - 30 days; The beneficial effects of the present invention: 1). The strength of the filter element is improved, and the service life is extended; 2). The washing efficiency of the cyclohexene hydration catalyst is improved; 3). The service life of the equipment is extended; 4). The backwashing effect of the filter component is improved, and the filter flux recovery effect of the filter element is good; 5). Alkali washing regeneration does not corrode the equipment, avoiding the safety problems caused by the corrosion of the acid washing solution to the equipment; 6). The pressure drop of the fluid passing through the metal filter element is small, and the energy loss is small; 7). The energy-saving effect is remarkable, and the operation cost is reduced. Brief Description of the Drawings Figure 1 It is a schematic process flow diagram of the present invention. Examples

[0007] The following examples are used to illustrate the present invention. It should be emphasized that these examples are only for further illustration of the present invention and should not be construed as limiting the scope of protection of the present invention. In the examples, after the cyclohexene hydration catalyst slurry to be cleaned enters the cleaning tank, the circulation of the cleaning tank, pre-filter, and filtration assembly and finally back to the cleaning tank is started. While high-purity water continuously enters the washing tank, the catalyst washing filtrate exits the system as cleaning waste liquid;

[0008] While the catalyst is being filtered and cleaned, the filtration assembly is periodically and grouped for backwashing operation with high-purity water in the backwash tank; When the filtration flux of the metal membrane filtration assembly decreases to the critical value, the filtration assembly needs to be chemically regenerated.

[0009] The operating parameters in the specific examples are as follows:

[0010]

Claims

1. A regeneration process for a washing and filtration assembly of a cyclohexene hydration catalyst, characterized in that, Comprising: A cleaning tank: used for storing and washing the hydrated catalyst slurry after degreasing and oxidative regeneration; A pre-filter: used for intercepting mechanical impurities and agglomerated solids in the hydrated catalyst slurry; A filtration assembly: used for intercepting solid catalysts in the hydrated catalyst slurry and removing impurities in the hydrated catalyst slurry at the same time; A backwash tank: used for containing high-purity water for backwashing the filtration assembly to perform physical backwashing on the filtration assembly; A regeneration liquid tank: used for containing the cleaning and regeneration liquid of the filtration assembly to perform chemical regeneration on the filtration assembly.

2. The process according to claim 1, characterized in that, The filtration assembly contains multiple groups of filtration devices connected in series and / or in parallel. The filtration device is provided with a metal filter element. The structure of the metal filter element is a single-layer and / or multi-layer composite structure. The filtration method is cross-flow filtration, and the transmembrane filtration pressure difference is 1-300 kPa.

3. The process according to claim 1 or 2, characterized in that, The outer diameter of the metal filter element is 8-36 mm, the filter element thickness is 1-3 mm, and the filter element filtration accuracy is 0.05-3.00 μm.

4. The process according to claim 1, characterized in that, The physical backwashing of the filtration assembly by the backwash liquid in the backwash tank is carried out by pressure drive or pump drive. The object of a single backwashing is one or more filters. The backwashing pressure difference is 0.5-6.0 bar. The backwashing time interval of a single filter is 5-240 min. The single backwashing time is 0.5-30 s. The backwash liquid medium is high-purity water, and the medium temperature is 50-90 °C.

5. The process according to claim 1, characterized in that, The chemical regeneration method of the filtration assembly is one or several of pickling regeneration, water washing regeneration, and alkali washing regeneration. The regeneration liquid tank is one or more. During the regeneration process of the filtration assembly, there is a self-circulation of the regeneration liquid and a filtrate circulation. The concentration of the regenerated acid liquid and the regenerated alkali liquid is 0.1-15 wt.%. The regeneration temperature is 5-90 °C, and the operation cycle after regeneration is 1-120 days.

6. The process according to claim 1, characterized in that, The pre-filter is provided with a metal filter element. The filtration accuracy of the metal filter element is 1-50 μm. The filtration method is dead-end filtration. The pre-filter is provided with a backwashing function and discharges the intercepted large-particle solids from the system in an intermittent manner.

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