JPS58156351A - Regeneration of catalyst for synthesis of methacrylic acid - Google Patents

Abstract

PURPOSE:To restore the activity of the titled catalyst, by subjecting a methacrylic acid synthesizing catalyst with reduced activity to heating treatment in the presence of steam to carry out regeneration treatment thereof without taking out the same from a reaction apparatus. CONSTITUTION:When the activity of a catalyst based on free phosphomolybdic acid and/or phosphovanadomolybdic acid used in preparing methacrylic acid by gas phase catalytic oxidation of methacrolein is lowered, it is treated at 70- 240 deg.C in a gas stream with steam partial pressure of 10vol%. By this method, regeneration can be carried out in a reaction apparatus and the catalyst becomes economical and is extended in the life thereof.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for recovering the activity of a psychocatalyst whose activity is reduced by continuing the reaction for a long period of time.

In particular, the present invention relates to a method for restoring the nettle activity by regenerating a catalyst whose activity has decreased (due to use in a reaction) without taking it out of the reaction apparatus.

It is known that the activity of heteropolyacid catalysts that synthesize methacrylic acid by air oxidation of methacrolein decreases during operation, and this decrease in catalytic activity leads to a decrease in the yield of methacrylic acid, and eventually It is necessary to shut down the operation, remove the catalyst, and refill it, which increases maintenance costs and reduces printing operation rate.

As a regeneration technology of free phosphomolybdic acid and/or phosphovanadomolybdic acid, JP-A-4-1137
Publication No. 33 is known. According to the specification, this method consists of the following steps. That is, /) the supported catalyst whose activity has decreased is extracted from the reactor. h) Extract with an aqueous medium. J) Fully recover the catalyst activity by heating and refluxing.) Support on a carrier. j) Filling the reactor.

According to the technology, the activity recovery is? ) process,
Since it is treated in a liquid phase, it requires as much as other mites and is not a good method from an industrial standpoint.

As a result of extensive research, the present inventors have discovered that free phosphomolybdic acid and/or lymphanatomolybdic acid recovers their activity in the presence of water vapor even in the gas phase, and have arrived at the present invention.

That is, the gist of the present invention is to produce free molybdic acid and /'! used in the production of methacrylic acid by vapor phase catalytic oxidation of methacrolein. A catalyst with reduced activity mainly composed of bamboo lymph natomolybdic acid is heated at a water vapor partial pressure / O
A method for regenerating a methacrylic acid synthesis catalyst, characterized in that the process is carried out in an air flow of V + 196 or more at a temperature of 7o-, 2<toC.According to the method of the present invention, the catalyst can be regenerated within the reactor, This means that a substantially long-life catalyst has been developed.

The free phosphomolybdic acid and/or lymphanatomolybdic acid in the method of the present invention has a major plane spacing of /jO of yy, tr, y, a, /6. o, de, to, +
,t,r.

Da, 71,3. daq, j, JJ, J, ko/, 3. /'
93. Gu,ri0. Q, 1III, 4(, J, 3, 3.
octopus.

It is a mixture of what appears to be a tetragonal crystal consisting of 3, Coj, J, 07 and Co, 07k, and the main plane spacing is /3. bu, ♂, it, s, zko, j
,,? ,? , da, dat.

Da, //, J, 9su, J, jJ, ,? , 0, 2.
It takes a diamond-shaped cubic crystal type consisting of 90 and ≦7 molecules, and produces a composition containing no alkali metals, thallium, or ammonium. The same X applies to free phosphomolybdic acid and/or phosphonatomolybdic acid containing steel.
Gives a line spectrum tube.

Book I! Free phosphomolybdic acid and/or lymphanatomolybdic acid preparation methods are generally used for the preparation of the inventive catalysts. As starting materials for catalyst preparation, molybdenum can be used as molybdenum trioxide, molybdic acid, phosphomolybdic acid, phosphorus-vanadomolybdic acid, and phosphorus can be used as starting materials such as phosphoric acid, phosphorous acid, phosphorus trioxide, phosphorus pentoxide, or phosphorus. Molybdic acid, phosphonatomolybdic acid, and phosphoric acid steel are used. In addition, vanadium includes vanadium pentoxide, vanadium trioxide, vanadium tetroxide, vanadyl oxalate, vanadyl sulfate, vanadyl dichloride, vanadium phosphate, lymphanatomolybdic acid, and copper raw materials include steel oxide and steel oxide II. , basic carbonate steel is commonly used.

For preparation, a predetermined amount of raw salt is weighed, water is added and dissolved under boiling reflux, and this is mixed to 100~/! Evaporate to dryness at OC temperature. The obtained dry product is further crushed into tablets to form a tablet catalyst, or sprinkled on a carrier to form a supported catalyst. Alternatively, during evaporation to dryness, the catalyst can be impregnated into a porous carrier and dried to obtain an impregnated catalyst. Supports include silica alumina 1 alumina, silicon carbide, pumice, diatomaceous earth, and titanium oxide with methacrolein oxidation activity and methacrolein,
A powder or molded product of a substance without methacrylic acid polymerization activity or a colloidal substance such as silica sol is used.

The regeneration process when carrying out the present invention is performed at 70~. It is carried out under temperature conditions of 1OC. In this case, if the treatment temperature is 70C or less, the treatment time tends to be long, and this is not necessarily an industrially preferable method. Furthermore, the higher the processing temperature, the smaller the regeneration effect, and at Koda OC or higher, it becomes difficult to regenerate even if time t is taken. The reason for this is that the catalyst mainly composed of free phosphomolybdic acid and/or lymphanatomolybdic acid undergoes complex structural changes depending on temperature and water content.
This is thought to be due to the formation of active food through the recycling of this structural change.

The partial pressure of water vapor during regeneration treatment should be at least Fl/Ovol, preferably in the range of 0'' to 100 vol. Air, nitrogen, combustion exhaust gas, etc. are all effective as the gas coexisting with the water vapor. It is.

EXAMPLES The present invention will be specifically described below with reference to Examples, but the present invention is not limited to these Examples.

In addition, in the specification of the present invention, the methaqrein reaction rate and methacrylic acid selectivity are defined as follows: O. The analysis was performed by gas chromatography. Example: 100 g of molybdenum trioxide, 4.3 g of vanadium pentoxide
Breath, oxidized secondary steel/g, orthophosphoric acid (tsl to precious 91k)
1. The mixture was placed in an ogf flask and purified water was added thereto, followed by IC treatment under heating and reflux for 74 hours to obtain a deep red homogeneous solution. This homogeneous solution was evaporated to dryness and sieved through a 10-'-/4 mesh. The composition of the catalyst obtained from this camphor is "1!P1.1vlCuO01041,45 in atomic ratio. This catalyst was packed into a Pyrex reaction tube with an inner diameter of /';/1.j;m-, and methacrolein 3.9 vol, acid 11!?, vol 1% b nitrogen qu, b vol I
G. Water vapor! ≠, the reaction was carried out under the conditions of covol 9G. In addition, the initial activity, change over time, and results after regeneration treatment of this catalyst are shown in Table 1. Regeneration conditions are gas composition steam 7j
The air was treated in an air stream at a temperature of λ5-ζ/oC for a time.

Table −/ Example Korg Molybdenum trioxide 100% as raw material salt. Og.

Vanadium pentoxide 4. ,? g, oxidized second steel-8λg.

Orthophosphoric acid (tS weight %) was sequentially added into the log flask, and after adding 1000 df of pure water, the mixture was heated under reflux for an hour to obtain a dark reddish-brown homogeneous solution.

This homogeneous solution was evaporated to dryness under reduced pressure using a rotary evaporator, and after tableting, it was crushed into 10 to 2 meshes and sieved.
The catalyst composition obtained in this way was Mo1! Child, ■□, 20u
It is O148039,48. This catalyst /7.611
A Pyrex reaction tube of &- was filled, and a gas having the same composition as in Example was introduced to cause a reaction.

Reaction conditions are 8v kozoo hr, 34101111
'The catalyst performance is methacrolein reaction rate (hereinafter abbreviated as OM), 111 methacrylic acid selectivity (hereinafter abbreviated as aMAA)
It was tt%. The peak temperature under the gas condition between the catalyst tubes was set as Q40 t:', and the process was carried out for 3yo again.
r: After returning to normal condition and testing the catalyst performance, CMA = 7, SMA = 7.54. What is the result of regeneration using this forced deterioration catalyst and changing the treatment temperature to ftoc%lto C1JQOC with air containing water vapor jθvol? They are shown in Table 1 as Examples 4 to 41, respectively. The regeneration treatment temperature is low and the efficiency is good.

Examples S-7 Reagent Phosphormolybdic Acid 9205''J4'MoOs
' In-0 (analytical value n=buo, o) 71. t gs
Vanadium pentoxide 3. #g.

Orthophosphoric acid (rj weight%) 0. 7 g of the flask was put into a flask, 500 - of pure water was added thereto, and VC/ was weighed for an hour under heating under reflux, and the filtrate was evaporated to dryness. This catalyst composition has an atomic ratio of "1"
2PIJv1.2042 □ eV in gas with the same composition ratio as this catalyst tube example/, Zr00hr, 3.3
The performance was evaluated at 0 C, subjected to forced deterioration treatment, and the nine catalysts were regenerated by changing the water vapor partial pressure. The results are shown in Table 1 as Examples J to 7.
Shown in 3.

Example 1 - // Pure water, too d, molybdenum trioxide J in a flask
0. Og, vanadium pentoxide, 43g, second steel oxide o3tg, orthophosphoric acid (trsIJ) 3.47g
.

Add 0.7λgk of boric acid and heat to reflux to obtain a homogeneous [1
't After filtration, dry and dry. It was sieved into comesh. This catalyst composition u MO12P1. IVIC! uo, 2 B
o, 406.1.

What is the catalyst performance under the same gas conditions as in Example/? In COOC, the methacrolein reaction rate was 1%, and the methacrylic acid selectivity was 1%. uaoc.

Catalyst performance after aO waiting time forced deterioration treatment is 5.3.20C
The methacrolein reaction rate was 4.2 and the methacrylic acid selectivity was 7. In this way, we will regenerate the deteriorated catalyst by changing the coexisting gas and show the results as an example.
/ is shown in Table 2.

Example/Co~l 30.0 g of molybdenum trioxide, cupric oxide O, ssg, and pure water in a double flask! 00 d, orthophosphoric acid (tS weight To
) q, o g t- was added and heated to reflux, and the solution was evaporated to dryness. This catalyst composition is MO□, P□, xCuo, t
It is a03L24. Is the performance of this catalyst 8V under the same gas conditions as in the example? ,! '/)hr, 341OC, the methacrolein reaction rate was 7bu-, and the methacrylic acid selectivity was 74%. Forced deterioration treatment was performed at 310C for 300 hours, and regeneration treatment was performed at COOC. The results are shown in Table 5 as Examples 7.2 to /41.

Claims (1)

[Scope of Claims] /) Free phosphomolybdic acid and/or phosphorus vanadomolybdic acid used in the production of methacrylic acid t-by gas phase catalytic oxidation of methacrolein. A method for regenerating a methacrylic acid synthesis catalyst characterized by treatment at a temperature of 70 to JII□C in an air flow with a water vapor partial pressure/Ovol of 4 or higher 2) Free phosphomolybdic acid and /l for methacrolein oxidation The method for regenerating a methacrylic acid synthesis catalyst according to claim 1, characterized in that the catalyst whose main component is linbana r-molybdenum soap contains steel.