CN1345717A - Methylamine catalyst and preparation process thereof - Google Patents

Abstract

The present invention provides a SiO2-Al2O3 methylamine catalyst composition and its preparatino method. Said catalyst contains 14-50 wt% of SiO2. The adoption of said catalyst can raise the conversino rate of methyl alcohol approach to 100%, can avoid the circulation of methyl alcohol so as to reduce the equipment and production cost. Besides, said invented catalyst possesses high selectivity of total amine, and the formation of by-products of dimethyl ether, N-methyl isobutylamine and N,N-dimethyl isobutylamine is less, and features no coking, stable catalytic performance and long service life.

Description

Methylamine catalyst and preparation method thereof

The present invention relates to a kind of methylamine catalyst and preparation method thereof.More specifically, the present invention relates to a kind ofly improvedly prepare high activated catalyst of methylamine and preparation method thereof by methyl alcohol and ammonia.

As everyone knows, methylamine is important organic amine, is one of staple product of basic organic synthesis, is widely used in fields such as agricultural chemicals, medicine, solvent, tensio-active agent, pharmacy and fodder additives.Traditional industrial process is to be raw material with methyl alcohol and ammonia, produce methylamine with gas phase catalysis amination method, the vaporization mixture that at first prepares methyl alcohol and ammonia, next in reactor, at about 220 ℃～about 500 ℃, under the pressure of normal atmosphere-about 50 crust, vaporization mixture reacts by beds.

The reaction product of ammonia and methyl alcohol is made up of mixture, water, ammonia and the unreacted methanol of three kinds of amine (being Monomethylamine (being called for short MMA), dimethylamine (being called for short DMA), Trimethylamine 99 (being called for short TMA)).In addition, dme (being called for short DME), N-methyl isobutylamine, N, N-dimethyl isobutylamine etc. also forms as by product.

At present, when methyl alcohol and ammonia are made methylamine on a large scale, in most cases be to utilize γ-Al ₂O ₃And amorphous silicon-Al catalysts.But, because γ-Al ₂O ₃Active low (methanol conversion has only 85-90%) therefore is easy to inactivation by its catalyzer that makes.Amorphous silicon, Al catalysts has catalytic performance preferably, what obtain in the presence of this catalyzer is near one of thermodynamic(al)equilibrium, two, the Trimethylamine 99 mixture is (at 400 ℃, under the 2MPa pressure and under the processing condition of N/C=1, one, two, being distributed as of Trimethylamine 99: Monomethylamine 15% (weight), dimethylamine 23% (weight), Trimethylamine 99 62% (weight)), because one, two, Trimethylamine 99 purposes difference, market is to one, two, and the demand of Trimethylamine 99 is different at different times, in order to make one, two, the distribution of Trimethylamine 99 meets the demand in market, usually adopts the methods a kind of or two kinds of amine that demand is little on the circulation market to reach the purpose of producing the amine that demand is many on the market.Though amorphous silicon, Al catalysts can be produced the amine that accords with the demands of the market by the method for circulation amine and distribute, because the easy coking and deactivation of such catalyzer, more catalyst changeout is more frequent, and this has brought very big inconvenience to industrial production.Therefore, people have carried out a lot of researchs, and knot carbon is few, the life-span long to seek, the catalyzer of stable performance.

United States Patent (USP) 4370503 (January 25 nineteen eighty-three is open) has been pointed out a kind of SiO of containing ₂Be 6% SiO ₂-Al ₂O ₃It is few that composition catalyzer, this catalyzer have knot carbon, the characteristics that the life-span is long, but this catalyst activity is lower, and conversion of methanol is 98%, and does not provide optionally data of total amine.Because methyl alcohol can not transform fully, stay the necessary recycle of methyl alcohol in the reaction solution, thereby increased production unit and productive expense.Total amine selectivity is meant one, two, the total selectivity of Trimethylamine 99.

Therefore,, a kind ofly tie not only that carbon is few, the life-span long, stable performance, Zong and methanol conversion height, catalyzer that the amine selectivity is high but still need to seek although be used for having multiple from the catalyzer of ammonia and methyl alcohol catalysis synthesis of methylamines.

So, an object of the present invention is to provide and a kind ofly tie not only that carbon is few, the life-span is long, stable performance, and methanol conversion height, total high catalyzer of amine selectivity.Adopt catalyzer of the present invention, can obtain transformation efficiency, can avoid the circulation of methyl alcohol, thereby reduce production unit and productive expense near 100%; And total amine selectivity of gained is very high, by product dme, N-methyl isobutylamine, and N, growing amounts such as N-dimethyl isobutylamine are few, and have the coking of being difficult for, and catalytic performance is stable, the characteristics that the life-span is long.

Another object of the present invention provides a kind of Preparation of catalysts method of the present invention.

Catalyzer of the present invention is by the SiO of 14～50wt% ₂, 50～86wt% Al ₂O ₃Form, be preferably the SiO of 15～30wt% ₂, the Al of 70～85wt% ₂O ₃, more excellent is the SiO of 18-22wt% ₂, the Al of 78-82wt% ₂O ₃

The fractional precipitation preparation method of methylamine catalyst composition of the present invention comprises the steps:

1) with AlCl ₃Or Al (NO ₃) ₃Putting into deionized water dissolves;

2) transfer solution PH between 7～11 by weak ammonia or NaOH solution down at 40～80 ℃;

3) add Na ₂SiO ₃Or water glass;

4) make catalyzer through forming steps such as aging, washing, drying, granulation, roastings.

The co-precipitation preparation method of methylamine catalyst composition of the present invention comprises the steps:

1) with a certain proportion of AlCl ₃And/or Al (NO ₃) ₃Aluminium source and Na ₂SiO ₃And/or water glass

The silicon source of glass is put into deionized water and is dissolved;

2) transfer solution PH between 7～11 by weak ammonia or NaOH solution down at 40～80 ℃;

3) make catalyzer through forming steps such as aging, washing, drying, moulding, roastings.

In a specific embodiments of the present invention, catalyst composition of the present invention is prepared as follows:

Step-by-step precipitation method: at first with Al source (AlCl ₃And/or Al (NO ₃) ₃, down with) put into deionized water and dissolve, then, transfer solution PH between 7～11 by weak ammonia or NaOH solution down at 40～80 ℃.Then add Si source (Na ₂SiO ₃And/or water glass, down together), use usual way again, as aging → washing → drying → granulation → roasting (400～600 ℃), make this invention catalyzer.

Coprecipitation method: at first deionized water is put in a certain proportion of Al source and Si source and dissolved, then, transfer solution PH between 7～11 by weak ammonia or NaOH solution down at 40～80 ℃, use usual way again, as aging → washing → drying → moulding → roasting (400～600 ℃), promptly make the catalyzer of this invention.

Catalyzer of the present invention uses with the right cylinder form usually, and its diameter is between 1～30mm, and is high between 1～30mm.Catalyzer of the present invention also can spherical and strip formation use.

Catalyzer will obtain higher activity, needs bigger specific surface area, because reactant and resultant in intrapore diffusion and back diffusion, need enough big aperture again, therefore, catalyzer specific area of the present invention should be at 100～300m simultaneously ²Between/the g, specific pore volume should be at 0.4～1.2cm ³Between/the g.

Fig. 1 adopts the catalyzer of the embodiment of the invention three to carry out total amine selectivity of 500 hours returning charge stability test gained and the methanol conversion change curve with the reaction times.Reaction conditions: T=410 ℃, P=1.6MPa, N/C=1.4, LHSV=1.5h ^-1Returning charge is formed: Trimethylamine 99/Monomethylamine=3.7, Monomethylamine and Trimethylamine 99 account for 14.8% of whole total feed.

We are surprised to find very much, contain higher SiO by employing ₂Ratio (14～50% SiO ₂) SiO ₂-Al ₂O ₃The composition catalyzer can make conversion of methanol bring up near 100%.Transformation efficiency near 100% can be avoided the circulation of methyl alcohol, thereby has reduced production unit and productive expense.In addition, we are surprised to find, and total amine selectivity of this catalyzer is very high, by product dme, N-methyl isobutylamine, and N, growing amounts such as N-dimethyl isobutylamine are few, and have the coking of being difficult for, and catalytic performance is stable, the characteristics that the life-span is long.

Comment the present invention below by embodiment, these embodiment are to further elaboration of the present invention, and effect without limits.Embodiment one step-by-step precipitation method prepares catalyzer of the present invention (the raw materials used chemical pure that is)

198 gram AlCl ₃6H ₂O is dissolved in the 306ml deionized water, and heating AlCl ₃Solution to 60 ℃ under agitation condition, drips 10% ammoniacal liquor to glue PH=7.5 then, drips Na again in glue ₂SiO ₃Solution (100 gram Na ₂SiO ₃9H ₂O is dissolved in the 400ml water), make SiO ₂: Al ₂O ₃Weight ratio=20: 80, and with between 10% ammoniacal liquor regulator solution PH=8.0～8.3, through aging → washing → drying → moulding → roasting (560 ℃, 4 hours).Prepared catalyzer has following rerum natura: profile 5 * 5mm cylindrical particle, specific surface 334m ²/ g, specific pore volume 0.92ml/g.

At internal diameter is in the stainless steel reactor of 26mm, and prepared catalyzer is estimated.Each 50ml catalyzer of filling.

Raw materials used methyl alcohol (Beijing chemical industry group company) and liquefied ammonia (Hebei Jin Yuan chemical inc) are industrial raw material, without further purification.

Analytical procedure: (Beijing Analytical Instrument Factory, model: 3420) carry out sample analysis, thermal conductivity cell detects gas-chromatography, inner mark method ration.

Hereinafter, x is a methanol conversion, S _AlwaysBe total amine selectivity, LHSV is an air speed, and they calculate by formula (1), formula (2), formula (3) respectively. Evaluating catalyst the results are shown in following table:

The N/C ratio	????X(％)	???S Always(％)	Amine distribution (mol%)
						Monomethylamine	Dimethylamine	Trimethylamine 99
			????1.1	????99.8	????99.4				????22?0	????26.7	????51.3
????2.2	????99.6	????99.0				????41.0	????33.6	????25.4

* reaction conditions: T=410 ℃, P=1.6MPa, LHSV=1.5 ^-1Returning charge is formed: Trimethylamine 99/Monomethylamine=3.7 (Wt), 4-19% (Wt) embodiment two step-by-step precipitation methods that Monomethylamine and Trimethylamine 99 sum account for total feed prepare catalyzer of the present invention (the raw materials used chemical pure that is)

198 gram AlCl ₃6H ₂O is dissolved in the 306ml deionized water, and heating AlCl ₃Solution to 60 ℃ under agitation condition, drips 10% ammoniacal liquor to glue PH=7.5 then, drips Na again in glue ₂SiO ₃Solution (100 gram Na ₂SiO ₃9H ₂O is dissolved in the 400ml water), make SiO ₂: Al ₂O ₃Weight ratio=35: 65, and with between 10% ammoniacal liquor regulator solution PH=8.0～8.3, through aging → washing → drying → moulding → roasting (560 ℃, 4 hours).Prepared catalyzer has following rerum natura: profile 5 * 5mm cylindrical particle, specific surface 295m ²/ g, specific pore volume 0.97ml/g.Under embodiment one described condition, estimate prepared catalyzer, it the results are shown in following table:

The N/C ratio	????X(％)	??S Always(％)	Amine distribution (mol%)
						Monomethylamine	Dimethylamine	Trimethylamine 99
			????1.1	????98.3	????96.3				????19.4	????23.5	????57.1
????2.2	????98.6	????95?9				????41.9	????34.4	????23.7

Embodiment three step-by-step precipitation methods prepare catalyzer of the present invention (the raw materials used chemical pure that is)

198 gram AlCl ₃6H ₂O is dissolved in the 306ml deionized water, and heating AlCl ₃Solution to 60 ℃ under agitation condition, drips 10% ammoniacal liquor to glue PH=7.5 then, drips Na again in glue ₂SiO ₃Solution (100 gram Na ₂SiO ₃9H ₂O is dissolved in the 400ml water), make SiO ₂: Al ₂O ₃Weight ratio=16: 84, and with between 10% ammoniacal liquor regulator solution PH=8.0～8.3, through aging → washing → drying → moulding → roasting (560 ℃, 4 hours).Prepared catalyzer has following rerum natura: profile 5 * 5mm cylindrical particle, specific surface 356m ²/ g, specific pore volume 0.89ml/g.Under embodiment one described condition, estimate prepared catalyzer, it the results are shown in following table:

The N/C ratio	????X(％)	??S Always(％)	Amine distribution (mol%)
						Monomethylamine	Dimethylamine	Trimethylamine 99
			????1.1	????99.1	????96.6				????20.5	????25.5	????54.0
????2.2	????99.8	????96?4				????44.1	????32.0	????23.9

Embodiment four coprecipitation methods prepare catalyzer of the present invention (the raw materials used chemical pure that is)

198 gram AlCl ₃6H ₂O and 47.5 gram Na ₂SiO ₃9H ₂O is dissolved in the 500ml deionized water, and heated solution to 60 ℃, under agitation condition, drips 10% ammoniacal liquor between glue PH=8.0～8.3 then, through aging → washing → drying → moulding → roasting (560 ℃, 4 hours).Prepared catalyzer has following rerum natura: profile 5 * 5mm cylindrical particle, specific surface 182m ²/ g, specific pore volume 0.22ml/g.Under embodiment one described condition, estimate prepared catalyzer, it the results are shown in following table:

The N/C ratio	????X(％)	??S Always(％)	Amine distribution (mol%)
						Monomethylamine	Dimethylamine	Trimethylamine 99
			????1.1	????99.5	????97.6				????19.5	????25.5	????55.0
????2.2	????99.4	????98.1				????43.2	????33.4	????23.4

Embodiment five step-by-step precipitation methods prepare catalyzer of the present invention (the raw materials used technical grade that is)

198 gram AlCl ₃6H ₂O is dissolved in the 306ml deionized water, and heating AlCl ₃Solution to 60 ℃ under agitation condition, drips 10% ammoniacal liquor to glue PH=7.5 then, drips water glass solution (5% SiO again in glue ₂), make SiO ₂/ Al ₂O ₃Weight ratio=0.25, and with between 10% ammoniacal liquor regulator solution PH=8.0～8.3, through aging → washing → drying → moulding → roasting (560 ℃, 4 hours).Prepared catalyzer has following rerum natura: profile 5 * 5mm cylindrical particle, specific surface 315m ²/ g, specific pore volume 0.90ml/g.Under embodiment one described condition, estimate prepared catalyzer, it the results are shown in following table:

The N/C ratio	????X(％)	??S Always(％)	Amine distribution (mol%)
						Monomethylamine	Dimethylamine	Trimethylamine 99
			????1.1	????99.5	????99.3				????22.3	????26.5	????51.2
????1.4	????99.6	????99.9				????30.1	????27.0	????42.9
			????2.2	????100.0	????99.1				????42.0	????32.6	????25.4
????2.6	????100.0	????98.7				????44.0	????33.8	????22.2

This catalyzer is in the returning charge stability experiment of 500 hours (Fig. 1), and (＞99.5%) does not fall in methanol conversion as follows, and total amine selectivity remains on more than 98.5% always.Comparative Examples 1 step-by-step precipitation method prepares US4370503 catalyzer (the raw materials used chemical pure that is)

198 gram AlCl ₃6H ₂O is dissolved in the 306ml deionized water, and heating AlCl ₃Solution to 60 ℃ under agitation condition, drips 10% ammoniacal liquor to glue PH=7.5 then, drips Na again in glue ₂SiO ₃Solution (100 gram Na ₂SiO ₃9H ₂O is dissolved in the 400ml water), make SiO ₂: Al ₂O ₃Weight ratio=6: 94, and with between 10% ammoniacal liquor regulator solution PH=8.0～8.3, through aging → washing → drying → moulding → roasting (560 ℃, 4 hours).Prepared catalyzer has following rerum natura: profile 5 * 5mm cylindrical particle, specific surface 258m ²/ g, specific pore volume 0.83ml/g.Under embodiment one described condition, estimate prepared catalyzer, it the results are shown in following table:

The N/C ratio	????X(％)	??S Always(％)	Amine distribution (mol%)
						Monomethylamine	Dimethylamine	Trimethylamine 99
			????1.1	????96.6	????94.3				????17.2	????25.8	????57.0
????2.2	????97.8	????95?4				????42.1	????36?2	????21.7

Claims (5)

1. methylamine catalyst composition, said composition is by the SiO of 14～50wt% ₂Al with 50～86wt% ₂O ₃Form.

2. according to the methylamine catalyst composition of claim 1, described SiO ₂Content is 15～30wt%, described Al ₂O ₃Content is 70～85wt%.

3. according to the methylamine catalyst composition of claim 2, described SiO ₂Content is 18～22wt%, described Al ₂O ₃Content is 78～82wt%.

4. according to each methylamine catalyst preparation of compositions method among the claim 1-3, comprise the steps:

1) with AlCl ₃Or Al (NO ₃) ₃Putting into deionized water dissolves;

2) transfer solution PH between 7～11 by weak ammonia or NaOH solution down at 40～80 ℃;

3) add Na ₂SiO ₃Or water glass;

4) moulding.

5. according to each methylamine catalyst preparation of compositions method among the claim 1-3, comprise the steps:

1) with a certain proportion of AlCl ₃And/or Al (NO ₃) ₃Aluminium source and Na ₂SiO ₃And/or the silicon source of water glass is put into deionized water and is dissolved;

2) transfer solution PH between 7～11 by weak ammonia or NaOH solution down at 40～80 ℃;

3) moulding.

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