After-treatment technology of Beckmann gas-phase rearrangement S-1 full-silica molecular sieve based catalyst

Technical Field

The invention belongs to the field of preparing catalyst, relates to a kind of Beckerman gas phase rearrangement in synthesis of caprolactam S-1 full-silicon molecular sieve post-treatment process, more specifically, relates to a low-cost processing S-1 full-silicon molecular sieve process.

Background Art

Caprolactam is an important chemical raw material, is a synthetic nylon 6 and engineering plastic monomer. The prior synthesis hexanolactam the process route of the liquid phase and gas phase are the main two BECKMANN rearrangement. In industrial production at present, mainly used sulfuric acid catalyzed liquid phase rearrangement process. The process is the cyclohexanone oxime in concentrated sulfuric acid or fuming sulfuric acid at a certain temperature under the action of a BECKMANN rearrangement reaction, the reaction system using ammonia and acidic generating caprolactam. The process technology is more matured, mild reaction conditions, and the conversion rate of the raw materials have a high product selectivity, but also have many defects. First concentrated sulfuric acid will corrode the apparatus, will be in the production process of harmful substances discharged, not in conformity with environmental protection concept development; at the same time also will produce a large amount of inexpensive ammonium sulfate (data display each producing 1 ton of caprolactam will produce 2 tons of ammonium sulphate), poor economic benefit. Therefore, in order to improve the economic efficiency and environmental benefits is for the purpose of process for the synthesis of caprolactam of the recent research has become an important direction. Although since the beginning of the eighties of last century, people, through changing the reactor forms and process conditions of use and of sulfuric acid to reduce the generation of ammonium sulfate, however, because of the use of sulfuric acid had not been fundamentally solve the problem.

In order to solve the above-mentioned problem, people began to research to solid acid as the catalyst production process for the gas-phase BECKMANN rearrangement. The process to use sulfuric acid can be avoided completely, therefore is very much in line with the direction of development of low-carbon environment is also expected to simultaneously, the production cost is reduced. Commonly used solid acid catalyst is mainly two types of oxide and molecular sieve. Wherein USP5914398, USP3586668, USP5942613, USP4717769, USP4709024, Appl.Catal. , 1999,188: 361, J.Catal. , 1994, 148 (1): 138, Catal.Lett. , 1998, 49 (3-4): 229 and other related reports that oxide catalyst life is relatively short, the conversion rate of cyclohexanone-oxime and caprolactam selectivity is not high, the regeneration effect is not good, do not yet have the industrial value. For example, USP5914398 to amorphous micro hole SiO₂-Al₂ O₃ as the catalyst, the cyclohexanone oxime weight vhsv (WHSV) =2.2h^-1 lower, reaction 23 hours later, the conversion rate of cyclohexanone-oxime to 97.9%, the caprolactam selectivity is only 81.4%. In addition it is also in the study to molecular sieve as the catalyst reaction effect. For example, J.Catal. , 1992,137: 252 to S-1 full-silicon molecular sieve as a catalyst, lifetime is less than 30h, the cyclohexanone oxime conversion rate is 90%, the caprolactam selectivity of 81%. Easy deactivation of the catalyst in the above-mentioned study, and caprolactam selectivity is not high.

Research shows that, to S-1 full-silicon molecular sieve catalyst to conduct appropriate after-treatment can significantly improve the response performance. For example, Chinese   J.Chem. , 2005, 26 (5): 417 reported NH₃-HNO₃ S-1 mixed solution can obviously lengthen the inactiviting speed molecular sieve; and Chinese   J.Chem. , 2006, 27 (3): 245 S-1 research found in the molecular sieve of the whole silicon 0.04% hydrofluoric acid treatment after the selectivity of the caprolactam is significantly improved; and USP5403801 report by the inorganic alkali solution-treated S-1 full-silicon molecular sieve, in WHSV=8h^-1, reaction 6.25h the conversion rate of cyclohexanone-oxime is 99.5%, the caprolactam selectivity of 96.5%, then inject the methanol-saturated air regeneration 23 hours, repeated 30 times, under the same reaction conditions the conversion rate of cyclohexanone-oxime is 95.3%, the caprolactam selectivity of 95.3%;

However, in the above-mentioned study S-1 hydrofluoric acid after all silicon molecular sieve is generally the conditions for processing the 100 [...] left and right, and to achieve this temperature needs to be heated to the hydrofluoric acid solution. As is well known, the hydrofluoric acid has very strong corrosive, thus available for selection of the material of the heat exchanger is very limited, often Monel alloy to its good corrosion resistance become the first selected. However, Monel alloy very expensive, the price of $high as hundreds of 1 kg, so that the alloy as the material of the high cost of the heat exchanger, is able to resolve the problem of how a direction of our study.

Content of the invention

In order to the problems in the prior art, this invention has offered a kind of Beckerman gas phase rearrangement S-1 full-silicon molecular sieve catalyst post-treatment process, solution of hydrofluoric acid in the prior art high-temperature corrosion resistance, small material selection range of the heat exchanger, the use of high cost alloy Monel the problem of high cost of the heat exchanger.

This invention is realized through the following technical scheme:

A Beckerman gas phase rearrangement S-1 full-silicon molecular sieve catalyst post-treatment process, comprising the following steps:

1) S-1 after the preparation of silicon molecular sieve treatment

Add de-ionized water will be a kind of strong acid to dilute until the H⁺ concentration is 0.01-0.1mol/l, the hydrofluoric acid diluted by adding deionized water to the mass fraction of 0.01-0.2%, then the two kinds of solution to volume ratio the 1 [...] 1-3 standby after being mixed;

Said strong acid is hydrochloric acid, sulfuric acid, a nitric acid.

After diluting the strong acid H⁺ concentration is 0.02-0.06mol/l.

The hydrofluoric acid the mass fraction of 0.02-0.16%.

2) S-1 full-silicon molecular sieve after-treatment process

Weighing 40-100g   S-1 full-silicon molecular sieve catalyst into polytetrafluoroethylene or polypropylene material in the reactor, the volume of the pores of a mixed solution of strong acid and hydrofluoric acid 200-1000ml is poured into the reactor, stirring is opened, the rotational speed is 50-100r/min, for reaction under the condition of room temperature 2-6h to stop after stirring, to deionized water to neutral; to this process is repeated 3 times, after the completion of reaction, the S-1 full-silicon molecular sieve drying, and 500-650 the roasting under [...] 3-6h, can get S-1 full-silicon molecular sieve catalyst product.

The room temperature conditions for the 25 [...].

How to preparation S-1 full-silicon molecular sieve does not belong to the scope of claim of the present invention. The invention relates to a content is directed against S-1 full-silicon molecular sieve after treatment areas is different from the previous processing technology in order to achieve the S-1 under the room temperature condition of the whole silicon the purpose of post-processing of the molecular sieve. More specifically, in the past the S-1 of all silicon molecular sieve containing hydrofluoric acid solution using a post-processing to the temperature conditions of 100 the left and right [...] , this has resulted in the hydrofluoric acid solution in the heating process of selected materials of the heat exchanger difficult. Through research of this invention improved S-1 full-silicon molecular sieve after formulation of processing solution, the post-treatment process can be carried out under the room temperature condition, does not need to be heated, thus obviously save the cost.

S-1 of the invention the whole silicon molecular sieve has the advantages of the method of post-processing:

1) the present invention through improved S-1 full-silicon molecular sieve after formulation of processing solution, the use of strong acid and hydrofluoric acid after the mixed solution of the treating liquid, so that the processing temperature after the process in the past in the 100 is reduced from about [...] can be carried out under the condition of room temperature. The present invention fundamentally solved in the past due to the hydrofluoric acid treatment process after the strong corrosive, the heat exchanger must be made of expensive monel the problem of the alloy, greatly save the equipment cost.

2) because the invention after-treatment temperature is room temperature conditions, thus greatly reducing the treatment process after the consumption of energy in, with the direction of development of energy-saving and emission reduction.

Mode of execution

The following specific embodiment with the further description of this invention. In the following embodiments in the comparative example, the following catalyst evaluation method:

Taking 0.5g   S-1 full-silicon molecular sieve and 5g the quartz sand evenly mixed to form a catalyst bed in the reactor, nitrogen; heating to 550 the reaction [...] 4h, lowering the temperature to the 340 [...] , mass fraction of the metering pump 40% cyclohexanone oxime methanol solution is injected into the catalyst bed, the airspeed is quality of cyclohexanone-oxime 4h^-1 gas phase BECKMANN rearrangement reaction of the caprolactam is obtained, to maintain the reaction 40h, each 10h sampling analysis of the product 1 time.

The following examples of embodiment and the comparative example of the embodiment. Wherein the embodiment is in order to prove the usefulness of the present invention of the claim in this invention after treatment in the range of under the conditions of catalyst preparation of S-1 of the whole silicon the results of the evaluation of the molecular sieve catalyst; comparison example is the preparation of the treatment process after S-1 full-silicon molecular sieve catalyst.

Embodiment 1:

Add deionized water to dilute to the hydrochloric acid concentration is H+ 0.02mol/l, the hydrofluoric acid diluted by adding deionized water to the mass fraction of 0.02%, then the two kinds of solution to volume ratio the 1 [...] 3 spare after mixing.

Weighing 40g   S-1 full-silicon molecular sieve catalyst into polytetrafluoroethylene or polypropylene material in the reactor, the volume of the pores of a mixed solution of strong acid and hydrofluoric acid 200 milliliter is poured into the reactor, stirring is opened, the rotational speed is 50r/min, for reaction under the condition of room temperature 2h to stop after stirring, to deionized water to neutral. To this process is repeated 3 times. After the reaction is finished, the S-1 full-silicon molecular sieve drying, for 500 the roasting under [...] 3h, can get S-1 full-silicon molecular sieve catalyst product.

S-1 full-silicon molecular sieve gas phase BECKMANN rearrangement of the catalyst synthesis of caprolactam evaluation results are shown in table 1.

Embodiment 2:

Add deionized water to dilute the sulphuric acid to H⁺ concentration is 0.03mol/l, the hydrofluoric acid diluted by adding deionized water to the mass fraction is 0.06%, then the two kinds of solution to volume ratio the 1 [...] 2 spare after mixing.

Weighing 60g   S-1 full-silicon molecular sieve catalyst into polytetrafluoroethylene or polypropylene material in the reactor, the volume of the pores of a mixed solution of strong acid and hydrofluoric acid 400 milliliter is poured into the reactor, stirring is opened, the rotational speed is 80r/min, at room temperature the reaction under the conditions of 3h to stop after stirring, to deionized water to neutral. Then under the same conditions, this reaction will be repeated 3 times. After the reaction is finished, the S-1 full-silicon molecular sieve drying, for the 550 roasting under [...] 4h, can get S-1 full-silicon molecular sieve catalyst product.

S-1 full-silicon molecular sieve gas phase BECKMANN rearrangement of the catalyst synthesis of caprolactam evaluation results are shown in table 1.

Embodiment 3:

The hydrochloric acid into deionized water to dilute until the H⁺ concentration is 0.05mol/l, the hydrofluoric acid by adding deionized water mass fraction is diluted to 0.1%, then the two kinds of solution to volume ratio the 1 [...] 1 spare after mixing.

Weighing 80g   S-1 full-silicon molecular sieve catalyst into polytetrafluoroethylene or polypropylene material in the reactor, the volume of the pores of a mixed solution of strong acid and hydrofluoric acid 800 milliliter is poured into the reactor, stirring is opened, the rotational speed is 100r/min, at room temperature the reaction under the conditions of 4h to stop after stirring, to deionized water to neutral. To this process is repeated 3 times. After the reaction is finished, the S-1 full-silicon molecular sieve drying, for 600 the roasting under [...] 5h, can get S-1 full-silicon molecular sieve catalyst product.

S-1 full-silicon molecular sieve gas phase BECKMANN rearrangement of the catalyst synthesis of caprolactam evaluation results are shown in table 1.

Embodiment 4:

The nitric acid is added to deionized water to dilute the concentration of H+ 0.06mol/l, the hydrofluoric acid diluted by adding deionized water to the mass fraction is 0.16%, then the two kinds of solution to volume ratio the 1 [...] 1 spare after mixing.

Weighing 100g   S-1 full-silicon molecular sieve catalyst into polytetrafluoroethylene or polypropylene material in the reactor, the volume of the pores of a mixed solution of strong acid and hydrofluoric acid 1000 milliliter is poured into the reactor, stirring is opened, the rotational speed is 100r/min, for reaction under the condition of room temperature 6h to stop after stirring, to deionized water to neutral. To this process is repeated 3 times. After the reaction is finished, the S-1 full-silicon molecular sieve drying, for the 650 roasting under [...] 6h, can get S-1 full-silicon molecular sieve catalyst product.

S-1 full-silicon molecular sieve gas phase BECKMANN rearrangement of the catalyst synthesis of caprolactam evaluation results are shown in table 1.

Embodiment 5:

The nitric acid is added to deionized water to dilute H⁺ concentration is 0.02mol/l, the hydrofluoric acid diluted by adding deionized water to the mass fraction of 0.04%, then the two kinds of solution to volume ratio the 1 [...] 2 spare after mixing.

Weighing 70g   S-1 full-silicon molecular sieve catalyst into polytetrafluoroethylene or polypropylene material in the reactor, the volume of the pores of a mixed solution of strong acid and hydrofluoric acid 900 milliliter is poured into the reactor, stirring is opened, the rotational speed is 90r/min, at room temperature the reaction under the conditions of 4h to stop after stirring, to deionized water to neutral. To this process is repeated 3 times. After the reaction is finished, the S-1 full-silicon molecular sieve drying, for the 550 roasting under [...] 5h, can get S-1 full-silicon molecular sieve catalyst product.

S-1 full-silicon molecular sieve gas phase BECKMANN rearrangement of the catalyst synthesis of caprolactam evaluation results are shown in table 1.

Comparison example:

Weighing 40g   S-1 of the whole silicon in the molecular sieve catalyst in a reactor, by adding 600 milliliter mass fraction 0.06% hydrofluoric acid solution, stirring is opened, the rotational speed is 50r/min, to the 6 [...] /min speed to rise to the 100 [...] , maintain 2h to stop after stirring, to deionized water to neutral. To this process is repeated 3 times. After the reaction is finished, the S-1 full-silicon molecular sieve drying, for 500 the roasting under [...] 3h, can get S-1 full-silicon molecular sieve catalyst product.

S-1 full-silicon molecular sieve gas phase BECKMANN rearrangement of the catalyst synthesis of caprolactam evaluation results are shown in table 1.

The present invention can realize S-1 of the whole silicon under the condition of room temperature of the molecular sieve after-treatment, after thorough solution containing hydrofluoric acid in the treatment solution of the corrosion problem. In the text the invention is not limited to the embodiment referred to, the above-mentioned embodiment is used to prove that the applicability, of the present invention without departing from the essence of the disclosed and described, does not go beyond the range of requirements under the right circumstances, can be according to the content disclosed in the specification, to select the corresponding treatment conditions.